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Sample records for anhydrous portland cements

  1. Improved quantification of alite and belite in anhydrous Portland cements by 29Si MAS NMR: Effects of paramagnetic ions

    DEFF Research Database (Denmark)

    Poulsen, Søren Lundsted; Kocaba, Vanessa; Le Saoût, Gwenn;

    2009-01-01

    The applicability, reliability, and repeatability of 29Si MAS NMR for determination of the quantities of alite (Ca3SiO5) and belite (Ca2SiO4) in anhydrous Portland cement was investigated in detail for 11 commercial Portland cements and the results compared with phase quantifications based...... on powder X-ray diffraction combined with Rietveld analysis and with Taylor-Bogue calculations. The effects from paramagnetic ions (Fe3+) on the spinning sideband intensities, originating from dipolar couplings between 29Si and the spins of the paramagnetic electrons, were considered and analyzed in spectra...

  2. Basalt waste added to Portland cement

    Directory of Open Access Journals (Sweden)

    Thiago Melanda Mendes

    2016-08-01

    Full Text Available Portland cement is widely used as a building material and more than 4.3 billion tons were produced in 2014, with increasing environmental impacts by this industry, mainly through CO2 emissions and consumption of non-removable raw materials. Several by-products have been used as raw materials or fuels to reduce environmental impacts. Basaltic waste collected by filters was employed as a mineral mixture to Portland cement and two fractions were tested. The compression strength of mortars was measured after 7 days and Scanning Electron Microscopy (SEM and Electron Diffraction Scattering (EDS were carried out on Portland cement paste with the basaltic residue. Gains in compression strength were observed for mixtures containing 2.5 wt.% of basaltic residue. Hydration products observed on surface of basaltic particles show the nucleation effect of mineral mixtures. Clinker substitution by mineral mixtures reduces CO2 emission per ton of Portland cement.

  3. Synthesis of pure Portland cement phases

    DEFF Research Database (Denmark)

    Wesselsky, Andreas; Jensen, Ole Mejlhede

    2009-01-01

    Pure phases commonly found in Portland cement clinkers are often used to test cement hydration behaviour in simplified experimental conditions. The synthesis of these phases is covered in this paper, starting with a description of phase relations and possible polymorphs of the four main phases...... in Portland cement, i.e. tricalcium silicate, dicalcium silicate, tricalcium aluminate and tetracalcium alumino ferrite. Details of the The process of solid state synthesis are is described in general including practical advice on equipment and techniques. Finally In addition, some exemplary mix compositions...

  4. Alkali binding in hydrated Portland cement paste

    NARCIS (Netherlands)

    Chen, W.; Brouwers, H.J.H.

    2010-01-01

    The alkali-binding capacity of C–S–H in hydrated Portland cement pastes is addressed in this study. The amount of bound alkalis in C–S–H is computed based on the alkali partition theories firstly proposed by Taylor (1987) and later further developed by Brouwers and Van Eijk (2003). Experimental data

  5. Portland cement-blast furnace slag blends in oilwell cementing applications

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, D.T.; DiLullo, G.; Hibbeler, J. [and others

    1995-12-31

    Recent investigations of blast furnace slag cementing technologies. have been expanded to include Portland cement/blast furnace slag blends. Mixtures of Portland cement and blast furnace slag, while having a long history of use in the construction industry, have not been used extensively in oilwell cementing applications. Test results indicate that blending blast furnace slag with Portland cement produces a high quality well cementing material. Presented are the design guidelines and laboratory test data relative to mixtures of blast furnace slag and Portland cements. Case histories delineating the use of blast furnace slag - Portland cement blends infield applications are also included.

  6. 76 FR 76760 - Gray Portland Cement and Cement Clinker From Japan

    Science.gov (United States)

    2011-12-08

    ... Portland Cement and Cement Clinker From Japan Determination On the basis of the record \\1\\ developed in the... antidumping duty order on gray Portland cement and cement clinker from Japan would be likely to lead to... the Commission are contained in USITC Publication 4281 (December 2011), entitled Gray Portland...

  7. Serviceability and Reinforcement of Low Content Whisker in Portland Cement

    Institute of Scientific and Technical Information of China (English)

    CAO Mingli; WEI Jianqiang; WANG Lijiu

    2011-01-01

    In order to explore the serviceability and reinforcement of CaCO3 whisker in portland cement matrix,the durability of CaCO3 whisker and effect of low whisker content(0%-4.0%)on the working performance and mechanical properties of portland cement were investigated.The experimental results show that CaCO3 whiskers have a good stability and serviceability in cement,and should not significantly alter the rheological properties of the cement paste.The flexural and compressive strength of portland cement reinforced by CaCO3 whiskers was increased by 33.3% and 12.83%,respectively.

  8. Alternative Fuel for Portland Cement Processing

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, Anton K; Duke, Steve R; Burch, Thomas E; Davis, Edward W; Zee, Ralph H; Bransby, David I; Hopkins, Carla; Thompson, Rutherford L; Duan, Jingran; ; Venkatasubramanian, Vignesh; Stephen, Giles

    2012-06-30

    The production of cement involves a combination of numerous raw materials, strictly monitored system processes, and temperatures on the order of 1500 °C. Immense quantities of fuel are required for the production of cement. Traditionally, energy from fossil fuels was solely relied upon for the production of cement. The overarching project objective is to evaluate the use of alternative fuels to lessen the dependence on non-renewable resources to produce portland cement. The key objective of using alternative fuels is to continue to produce high-quality cement while decreasing the use of non-renewable fuels and minimizing the impact on the environment. Burn characteristics and thermodynamic parameters were evaluated with a laboratory burn simulator under conditions that mimic those in the preheater where the fuels are brought into a cement plant. A drop-tube furnace and visualization method were developed that show potential for evaluating time- and space-resolved temperature distributions for fuel solid particles and liquid droplets undergoing combustion in various combustion atmospheres. Downdraft gasification has been explored as a means to extract chemical energy from poultry litter while limiting the throughput of potentially deleterious components with regards to use in firing a cement kiln. Results have shown that the clinkering is temperature independent, at least within the controllable temperature range. Limestone also had only a slight effect on the fusion when used to coat the pellets. However, limestone addition did display some promise in regards to chlorine capture, as ash analyses showed chlorine concentrations of more than four times greater in the limestone infused ash as compared to raw poultry litter. A reliable and convenient sampling procedure was developed to estimate the combustion quality of broiler litter that is the best compromise between convenience and reliability by means of statistical analysis. Multi-day trial burns were conducted

  9. Dehydration kinetics of Portland cement paste at high temperature

    NARCIS (Netherlands)

    Zhang, Q.; Ye, G.

    2012-01-01

    Portland cement paste is a multiphase compound mainly consisting of calcium-silicate-hydrate (CSH) gel, calcium hydroxide (CH) crystal, and unhydrated cement core. When cement paste is exposed to high temperature, the dehydration of cement paste leads to not only the decline in strength, but also th

  10. 76 FR 24519 - Gray Portland Cement and Cement Clinker From Japan; Institution of a Five-Year Review Concerning...

    Science.gov (United States)

    2011-05-02

    ... COMMISSION Gray Portland Cement and Cement Clinker From Japan; Institution of a Five-Year Review Concerning the Antidumping Duty Order on Gray Portland Cement and Cement Clinker From Japan AGENCY: United States... determine whether revocation of the antidumping duty order on gray portland cement and cement clinker...

  11. Structural Investigations of Portland Cement Components, Hydration, and Effects of Admixtures by Solid-State NMR Spectroscopy

    DEFF Research Database (Denmark)

    Skibsted, Jørgen Bengaard; Andersen, Morten D.; Jakobsen, Hans Jørgen

    2006-01-01

    for the C-S-H phase formed during hydration. It will be demonstrated that Al3+ and flouride guest-ions in the anhydrous and hydrated calcium silicates can be studied in detail by 27Al and 19F MAS NMR, thereby providing information on the local structure and the mechanisms for incorporation of these ions...... in the cement phases. The role of flouride ions is of special interest for mineralized Portland cements and it demonstrated that the location of these anions in anhydrous and hydrated Portland cements can be clarified using 19F MAS or 29Si{19F} CP/MAS NMR despite these cements contain only about 0.2 wt...

  12. Radiopacity of portland cement associated with different radiopacifying agents.

    Science.gov (United States)

    Húngaro Duarte, Marco Antonio; de Oliveira El Kadre, Guâniara D'arc; Vivan, Rodrigo Ricci; Guerreiro Tanomaru, Juliane Maria; Tanomaru Filho, Mário; de Moraes, Ivaldo Gomes

    2009-05-01

    This study evaluated the radiopacity of Portland cement associated with the following radiopacifying agents: bismuth oxide, zinc oxide, lead oxide, bismuth subnitrate, bismuth carbonate, barium sulfate, iodoform, calcium tungstate, and zirconium oxide. A ratio of 20% radiopacifier and 80% white Portland cement by weight was used for analysis. Pure Portland cement and dentin served as controls. Cement/radiopacifier and dentin disc-shaped specimens were fabricated, and radiopacity testing was performed according to the ISO 6876/2001 standard for dental root sealing materials. Using Insight occlusal films, the specimens were radiographed near to a graduated aluminum stepwedge varying from 2 to 16 mm in thickness. The radiographs were digitized and radiopacity compared with the aluminum stepwedge using Digora software (Orion Corporation Soredex, Helsinki, Finland). The radiographic density data were converted into mmAl and analyzed statistically by analysis of variance and Tukey-Kramer test (alpha = 0.05). The radiopacity of pure Portland cement was significantly lower (p oxide and Portland cement/lead oxide presented the highest radiopacity values and differed significantly from the other materials (p oxide presented the lowest radiopacity values of all mixtures (p < 0.05). All tested substances presented higher radiopacity than that of dentin and may potentially be added to the Portland cement as radiopacifying agents. However, the possible interference of the radiopacifiers with the setting chemistry, biocompatibility, and physical properties of the Portland cement should be further investigated before any clinical recommendation can be done.

  13. 76 FR 2832 - National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing...

    Science.gov (United States)

    2011-01-18

    ... the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants... (NESHAP) from the Portland Cement Manufacturing Industry and Standards of Performance (NSPS) for Portland Cement Plants. The final rules were published on September 9, 2010. This direct final action...

  14. 75 FR 54969 - National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing...

    Science.gov (United States)

    2010-09-09

    ... Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants; Final Rule... Hazardous Air Pollutants From the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule. SUMMARY: EPA...

  15. 77 FR 46371 - National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing...

    Science.gov (United States)

    2012-08-03

    ... the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants... Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants,'' which was published in the Federal Register on July 18, 2012....

  16. 76 FR 28318 - National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing...

    Science.gov (United States)

    2011-05-17

    ... the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants... Pollutants emitted by the Portland Cement Industry and the New Source Performance Standards for Portland Cement Plants issued under sections 112(d) and 111(b) of the Clean Air Act, respectively. The EPA is...

  17. 76 FR 2860 - National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing...

    Science.gov (United States)

    2011-01-18

    ... the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants... of Performance (NSPS) for Portland Cement Plants. The final rules were published on September 9, 2010... Portland Cement Manufacturing Industry Docket, Docket ID No. EPA-HQ-OAR-2002-0051, 1200 Pennsylvania...

  18. EFFECT OF PORTLAND-POZZOLAN CEMENTS ON CONCRETE MATURITY

    Directory of Open Access Journals (Sweden)

    Arın YILMAZ

    2004-03-01

    Full Text Available The maturity concept expressed by the combined effect of time and temperature on the concrete is a useful technique for prediction of the strength gain of concrete. According to maturity concept, samples of the same concrete at same maturity whatever combination of temperature and time, have approximately the same strength. Many maturity functions have been proposed for the last 50 years. The validity of these functions are only for ordinary portland cements. In this study, the suitable of traditional maturity functions for different types of Portland-pozzolan cements were investigated and a new maturity-strength relationship was tried to be established. For this purpose, four different pozzolans and one Portland cement was selected. Portland-pozzolan cements were prepared by using three different replacement amounts of % 5, % 20 and 40 % by weight of cement.

  19. Modification of Portland cement mortars with cactus gum

    OpenAIRE

    Hernandez-Zaragoza, Juan-Bosco; Caballero-Badillo, Carlos-Eduardo; Rosas-Juarez, Arnulfo; Lopez-Lara, Teresa; Hinojosa-Torres, Jaime; Castano, Victor-Manuel

    2007-01-01

    ????????, ?? ?????????? ??????? ?? ?????? ????????-???????, ??? ???????????????? ? ????????? ???????????, ???????????? ?????????? ?????????? ??????, ????????? ? ????????? ?????????????? ???????. ???????? ?????????? ???????? ??? ????????? ???????? ??? ????????? ?? 65 %, ????????? ?? ???????????? ?????????. Portland cement-based mortars of the standard type used for modern constructions, were modified by adding liophilized cactus gum, extracted froman indigenous Mexican cactus. The results show...

  20. 76 FR 50252 - Gray Portland Cement and Cement Clinker From Japan; Scheduling of an Expedited Five-Year Review...

    Science.gov (United States)

    2011-08-12

    ... COMMISSION Gray Portland Cement and Cement Clinker From Japan; Scheduling of an Expedited Five-Year Review Concerning the Antidumping Duty Order on Gray Portland Cement and Cement Clinker From Japan AGENCY: United... cement and cement clinker from Japan would be likely to lead to continuation or recurrence of...

  1. Hydration process in Portland cement blended with activated coal gangue

    Institute of Scientific and Technical Information of China (English)

    Xian-ping LIU; Pei-ming WANG; Min-ju DING

    2011-01-01

    This paper deals with the hydration of a blend of Portland cement and activated coal gangue in order to determine the relationship between the degree of hydration and compressive strength development.The hydration process was investigated by various means:isothermal calorimetry,thermal analysis,non-cvaporable water measurement,and X-ray diffraction analysis.The results show that the activated coal gangue is a pozzolanic material that contributes to the hydration of the cement blend.The pozzolanic reaction occurs over a period of between 7 and 90 d,consuming portlandite and forming both crystal hydrates and ill-crystallized calcium silicate hydrates.These hydrates are similar to those found in pure Portland cement.The results show that if activated coal gangue is substituted for cement at up to 30% (w/w),it does not significantly affect the final compressive strength of the blend.A long-term compressive strength improvement can in fact be achieved by using activated coal gangue as a supplementary cementing material.The relationship between compressive strength and degree of hydration for both pure Portland cement and blended cement can be described with the same equation.However,the parameters are different since blended cement produces fewer calcium silicate hydrates than pure Portland cement at the same degree of hydration.

  2. Influence of Cellulose Ethers on Hydration Products of Portland Cement

    Institute of Scientific and Technical Information of China (English)

    MA Baoguo; OU Zhihua; JIAN Shouwei; XU Rulin

    2011-01-01

    Cellulose ethers are widely used to mortar formulations, and it is significant to understand the interaction between cellulose ethers and cement pastes. FT-IR spectra, thermal analysis and SEM are used to investigate hydration products in the cement pastes modified by HEMC and HPMC in this article. The results show that the hydration products in modified cement pastes were finally identical with those in the unmodified cement paste, but the major hydration products, such as CH (calcium hydroxide), ettringite and C-S-H, appeared later in the modified cement pastes than in the unmodified cement paste. The cellulose ethers decrease the outer products and increase inner products of C-S-H gels. Compared to unmodified cement pastes, no new products are found in the modified cement pastes in the present experiment. The HEMC and HPMC investigation shows almost the same influence on the hydration products of Portland cement.

  3. Laboratory Investigation on the Strength Gaining of Brick Aggregate Concrete Using Ordinary Portland Cement and Portland Composite Cement

    Directory of Open Access Journals (Sweden)

    Hoque M H, Numen E H, Islam N., Mohammed

    2014-05-01

    Full Text Available This study focused on the laboratory investigation of strength variation of brick aggregate concrete made with ordinary Portland cement (OPC and Portland composite cement (PCC.The investigation was conducted by testing concrete cylinder specimens at different ages of concrete with concrete mix ratios: 1:1.5:3 and 1:2:4 by volume and with water cement ratios=0.45 and 0.60. The test result reveals that at the early age, concrete composed with OPC attained larger compressive strength than the concrete made of PCC. However, in the later age concrete made with PCC achieved higher strength than OPC.

  4. Apatite formation on calcined kaolin-white Portland cement geopolymer.

    Science.gov (United States)

    Pangdaeng, S; Sata, V; Aguiar, J B; Pacheco-Torgal, F; Chindaprasirt, P

    2015-06-01

    In this study, calcined kaolin-white Portland cement geopolymer was investigated for use as biomaterial. Sodium hydroxide and sodium silicate were used as activators. In vitro test was performed with simulated body fluid (SBF) for bioactivity characterization. The formation of hydroxyapatite bio-layer on the 28-day soaked samples surface was tested using SEM, EDS and XRD analyses. The results showed that the morphology of hydroxyapatite was affected by the source material composition, alkali concentration and curing temperature. The calcined kaolin-white Portland cement geopolymer with relatively high compressive strength could be fabricated for use as biomaterial. The mix with 50% white Portland cement and 50% calcined kaolin had 28-day compressive strength of 59.0MPa and the hydroxyapatite bio-layer on the 28-day soaked sample surface was clearly evident.

  5. 77 FR 42367 - National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing...

    Science.gov (United States)

    2012-07-18

    ... Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants; Proposed Rule #0;#0;Federal Register / Vol. 77 , No. 138 / Wednesday...-AQ93 National Emission Standards for Hazardous Air Pollutants for the Portland Cement...

  6. 76 FR 78240 - Gray Portland Cement and Clinker From Japan: Continuation of Antidumping Duty Order

    Science.gov (United States)

    2011-12-16

    ... International Trade Administration Gray Portland Cement and Clinker From Japan: Continuation of Antidumping Duty... antidumping duty order on gray portland cement and clinker from Japan, pursuant to section 751(c) of the... International Trade Commission (ITC) that revocation of the antidumping duty order on gray portland cement...

  7. Pavement management and rehabilitation of portland cement concrete pavements

    Science.gov (United States)

    Zegeer, C. V.; Agent, K. R.; Rizenbergs, R. L.; Curtayne, P. C.; Scullion, T.; Pedigo, R. D.; Hudson, W. R.; Roberts, F. L.; Karan, M. A.; Haas, R.

    Pavement management and rehabilitation projects and techniques are discussed. The following topics are discussed: economic analyses and dynamic programming in resurfacing project selection; implementation of an urban pavement management system; pavement performance modeling for pavement management; illustration of pavement management: from data inventory to priority analysis; rehabilitation of concrete pavements by using portland cement concrete overlays; pavement management study: Illinois tollway pavement overlays; resurfacing of plain jointed-concrete pavements; design procedure for premium composite pavement; model study of anchored pavement; prestressed concrete overlay at O'Hare International Airport: in-service evaluation; and, bonded portland cement concrete resurfacing.

  8. Applications of solid-state Nuclear Magnetic Resonance (NMR) in studies of Portland cements-based materials

    DEFF Research Database (Denmark)

    Skibsted, Jørgen; Andersen, Morten Daugaard; Jakobsen, Hans Jørgen

    2007-01-01

    Solid-state NMR spectroscopy represents an important research tool in the characterization of a range of structural properties for cement-based materials. Different approaches of the technique can be used to obtain information on hydration kinetics, mobile and bound water, porosity, and local...... atomic structures. After a short introduction to these NMR techniques, it is exemplified how magic-angle spinning (MAS) NMR can provide quantitative and structural information about specific phases in anhydrous and hydrated Portland cements with main emphasis on the incorporation of Al3+ ions...

  9. 78 FR 10005 - National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing...

    Science.gov (United States)

    2013-02-12

    ... Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants; Final Rule #0;#0;Federal Register / Vol. 78 , No. 29 / Tuesday... RIN 2060-AQ93 National Emission Standards for Hazardous Air Pollutants for the Portland...

  10. Analysis of Chemical Composition of Portland Cement in Ghana: A Key to Understand the Behavior of Cement

    Directory of Open Access Journals (Sweden)

    Mark Bediako

    2015-01-01

    Full Text Available The performance of Portland cement in concrete or mortar formation is very well influenced by chemical compositions among other factors. Many engineers usually have little information on the chemical compositions of cement in making decisions for the choice of commercially available Portland cement in Ghana. This work analyzed five different brands of Portland cement in Ghana, namely, Ghacem ordinary Portland cement (OPC and Portland limestone cement (PLC, CSIR-BRRI Pozzomix, Dangote OPC, and Diamond PLC. The chemical compositions were analyzed with X-Ray Fluorescence (XRF spectrometer. Student’s t-test was used to test the significance of the variation in chemical composition between standard literature values and each of the commercial cement brands. Analysis of variance (ANOVA was also used to establish the extent of variations between chemical compositions and brand name of the all commercial Portland cement brands. Student’s t-test results showed that there were no significant differences between standard chemical composition values and that of commercial Portland cement. The ANOVA results also indicated that each brand of commercial Portland cement varies in terms of chemical composition; however, the specific brands of cement had no significant differences. The study recommended that using any brand of cement in Ghana was good for any construction works be it concrete or mortar formation.

  11. Corrosion inhibitor mechanisms on reinforcing steel in Portland cement pastes

    Science.gov (United States)

    Martin, Farrel James

    2001-07-01

    The mechanisms of corrosion inhibitor interaction with reinforcing steel are investigated in the present work, with particular emphasis on effects associated with corrosion inhibitors admixed into Portland cement paste. The principal objective in reinforcing steel corrosion inhibition for Portland cement concrete is observed to be preservation of the naturally passive steel surface condition established by the alkaline environment. Introduction of chloride ions to the steel surface accelerates damage to the passive film. Excessive damage to the passive film leads to loss of passivity and a destabilization of conditions that facilitate repair of the passive film. Passive film preservation in presence of chloride ions is achieved either through stabilization of the passive film or by modification of the chemical environment near the steel surface. Availability of inhibitors to the steel surface and their tendency to stabilize passive film defects are observed to be of critical importance. Availability of admixed corrosion inhibitors to the passive film is affected by binding of inhibitors during cement paste hydration. It is determined that pore solution concentrations of inorganic admixed inhibitors tend to be lower than the admixed concentration, while pore solution concentrations of organic admixed inhibitors tend to be higher than the admixed concentration. A fundamental difference of inhibitor function is observed between film-forming and defect stabilizing corrosion inhibitors. Experiments are conducted using coupons of reinforcing steel that are exposed to environments simulating chloride-contaminated Portland cement concrete. A study of the steel/cement paste interface is also performed, and compounds forming at this interface are identified using X-Ray diffraction.

  12. Scrap tire ashes in portland cement production

    Directory of Open Access Journals (Sweden)

    Mónica Adriana Trezza

    2009-01-01

    Full Text Available Scrap tires are not considered harmful waste, but their stocking and disposal are a potential health and environmental risk. Properly controlled calcinations at high temperatures make tire combustion an interesting alternative due to its high calorific power, comparable to that of fuel-oil. Consequently, using them as an alternative combustible material in cement kilns makes it possible to give it a valuable use. However, it remains to be assured whether the impurities added to the clinker through these fuels do not affect its structure or properties.This paper shows the studies carried out on different clinkers under laboratory conditions with different levels of addition of scrap tire ashes, added by partially replacing traditional fuel in cement kilns.

  13. Polypropylene Fibers in Portland Cement Concrete Pavements.

    Science.gov (United States)

    1992-08-01

    Bibliography on Fiber- Reinforced Cement and Concrete," Miscellaneous Paper C-76-6, with supplements 1, 2, 3, and 4 ( 1977 , 1979, 1980, and 1982), US Army... Mindess , S., Bentur, A., Yan, C., and Vondran, G., "Impact Resistance of Concrete Containing Both Conventional Steel Reinforcement and Fibrillated...Roads, Streets, Walks, and Open Storage Areas," TM 5-822-6/AFM 88-7, Chap. 7, Washington, DC, 1977 . 18. __ , "Concrete Floor Slabs on Grade Subjected

  14. Alkali segregation in Portland cement pastes

    Directory of Open Access Journals (Sweden)

    Triviño, F.

    1966-09-01

    Full Text Available Not availableEn el presente trabajo se pone de manifiesto experimentalmente la formación y presencia de aphthitalita -sulfato doble de potasio y sodio en la relación S04K2/S04Na2 = 3/1 en las pastas puras de cemento portland, desde el comienzo del fraguado de las mismas. Se estudia el mecanismo de la citada formación, íntimamente relacionada con el proceso general de formación de eflorescencias salinas, a base de una emigración de sulfatos alcalinos hacia las partes externas de las pastas, en virtud de fenómenos de exudación equivalentes a arrastres capilares. Se sintetiza y aísla la aphthitalita por dos procedimientos y se obtiene su difractograma.de rayos· X, a efectos de su identificación y de la confirmación de los resultados experimentales obtenidos, así como de la interpretación de los mismos.

  15. Hydration of Portland cement with additions of calcium sulfoaluminates

    Energy Technology Data Exchange (ETDEWEB)

    Le Saout, Gwenn, E-mail: gwenn.le-saout@mines-ales.fr [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Lothenbach, Barbara [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Hori, Akihiro [DENKA Chemicals GmbH, Wehrhahn-Center, Cantadorstr. 3, D-40211 Duesseldorf (Germany); Higuchi, Takayuki [Denki Kagaku Kogyo Kabushiki Kaisha (DENKA), Omi, Itoigawa, Niigata, 949-0393 (Japan); Winnefeld, Frank [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)

    2013-01-15

    The effect of mineral additions based on calcium aluminates on the hydration mechanism of ordinary Portland cement (OPC) was investigated using isothermal calorimetry, thermal analysis, X-ray diffraction, scanning electron microscopy, solid state nuclear magnetic resonance and pore solution analysis. Results show that the addition of a calcium sulfoaluminate cement (CSA) to the OPC does not affect the hydration mechanism of alite but controls the aluminate dissolution. In the second blend investigated, a rapid setting cement, the amorphous calcium aluminate reacts very fast to ettringite. The release of aluminum ions strongly retards the hydration of alite but the C-S-H has a similar composition as in OPC with no additional Al to Si substitution. As in CSA-OPC, the aluminate hydration is controlled by the availability of sulfates. The coupling of thermodynamic modeling with the kinetic equations predicts the amount of hydrates and pore solution compositions as a function of time and validates the model in these systems.

  16. 76 FR 54206 - Gray Portland Cement and Clinker From Japan: Final Results of the Expedited Third Sunset Review...

    Science.gov (United States)

    2011-08-31

    ... International Trade Administration Gray Portland Cement and Clinker From Japan: Final Results of the Expedited... review of the antidumping duty order on gray portland cement and clinker from Japan. As a result of this... duty order on gray portland cement and clinker from Japan \\1\\ pursuant to section 751(c) of the...

  17. The influence of clay additives in Portland cement on the compressive strength of the cement stone

    Directory of Open Access Journals (Sweden)

    A.R. Gaifullin

    2015-11-01

    Full Text Available The introduction of mineral additives to binders, especially to Portland cement, is one of the promising trends for solving the resource and energy saving problems, as well as problems of environmental protection during production and application. Expanding the supplementary cementitious materials resource base can be achieved through the use of natural pozzolans and thermally activated polymineral clays(commonly known as glinites in Russia. One type of glinite is metakaolin, which is obtained by calcination of kaolin clays. Metakaolin is widely and effectively used as a pozzolanic additive due to its beneficial effect on the physical and mechanical properties of Portland cement-based materials. The obstacle to its wide production and use are the limited deposits of pure kaolin clays in many countries, including the Russian Federation. In this respect, the studies of pozzolanic activity of the most common mineral clays and their use in some countries have significantly advanced. Similar studies were widely performed in the 1940s in USSR. It seems reasonable to renew this trend to provide a scientific base for the production of local pozzolans made of clays commonly used in different regions. Comparative studies of the effect of 5 clays differing in mineral and chemical composition, calcination temperature and specific surface area, and high-quality metakaolin, on the strength of hardened Portland cement paste have been performed. It has been established that introducing 5…10 % of composite clays calcined at 400…8000 C° and milled to a specific surface area of 290…800 m2/kg into Portland cement enhanced the strength of the hardened cement paste considerably better than the introduction of metakaolin with a specific surface area of 1200 m2/kg. The findings of the study suggest that many kinds of commonly used polymineral clays have a specific calcination temperature and dispersity, which results in a higher pozzolanic activity compared with

  18. Effect of different mixing methods on the physical properties of Portland cement

    OpenAIRE

    Shahi, Shahriar; Ghasemi, Negin; Rahimi, Saeed; Yavari, Hamidreza; Samiei, Mohammad; Jafari, Farnaz

    2016-01-01

    Background The Portland cement is hydrophilic cement; as a result, the powder-to-liquid ratio affects the properties of the final mix. In addition, the mixing technique affects hydration. The aim of this study was to evaluate the effect of different mixing techniques (conventional, amalgamator and ultrasonic) on some selective physical properties of Portland cement. Material and Methods The physical properties to be evaluated were determined using the ISO 6786:2001 specification. One hundred ...

  19. Conduction calorimetric studies of ternary binders based on Portland cement, calcium aluminate cement and calcium sulphate

    OpenAIRE

    Torrens Martín, David; Fernández Carrasco, Lucía; Blanco Varela, M.Teresa

    2013-01-01

    Different binders of Portland cement, calcium aluminate cement and calcium sulphate (PC/CAC/CS) have been investigated to determinate the in¿uence the CAC and CS amount in the reactions mechanism. Several mixtures were studied, ratios of 100, 85/15 and 75/25 of PC/CAC with 0, 3 and 5 % of CS. Conduction calorimetric technique was used to follow the hydration during 100 h. The XRD and FTIR techniques were used as support in the analysis of the hydration products. The results have shown tha...

  20. Comparison of the root-end sealing ability of MTA and Portland cement.

    Science.gov (United States)

    Islam, Intekhab; Chng, Hui Kheng; Yap, Adrian U Jin

    2005-08-01

    The aim of this study was to compare the in vitro sealing ability of ProRoot MTA, ProRoot MTA (Tooth-Coloured Formula), ordinary Portland cement and white Portland cement when used as root-end filling materials. Twenty-four single-rooted human premolars were prepared and obturated using standard techniques, then retrofilled with the test materials. The prepared teeth were immersed in 1% methylene blue dye for 72 hours and then assessed for dye leakage. The depth of dye penetration was measured and expressed as a percentage of the length of the retrofilling. Data was analysed using ANOVA and Fisher's Least Significant Test (LSD) (p cements, it is reasonable to consider Portland cement as a possible substitute for MTA as a root-end filling material. However, further tests, especially in vivo biocompatibility tests, need to be conducted before Portland cement can be recommended for clinical use.

  1. Research on the nanolevel influence of surfactants on structure formation of the hydrated Portland cement compositions

    Directory of Open Access Journals (Sweden)

    Guryanov Alexander

    2016-01-01

    Full Text Available The research of the structure formation process on a nanolevel of the samples of hydrated Portland cement compositions containing the modifying additives has been conducted with the help of small angle neutron scattering method. Carbonate and aluminum alkaline slimes as well as the complex additives containing surfactants were used as additives. The influence of slimes and surfactants on structural parameters change of Portland cement compositions of the average size of the disseminating objects, fractal dimension samples is considered. These Portland cement compositions are shown to be fractal clusters.

  2. Pulpotomies with portland cement in human primary molars

    Directory of Open Access Journals (Sweden)

    Taísa Regina Conti

    2009-02-01

    Full Text Available Two clinical cases in which Portland cement (PC was applied as a medicament after pulpotomy of mandibular primary molars in children are presented. Pulpotomy using PC was carried out in two mandibular first molars and one mandibular second molar, which were further followed-up. At the 3, 6 and 12-month follow-up appointments, clinical and radiographic examinations of the pulpotomized teeth and their periradicular area revealed that the treatments were successful in maintaining the teeth asymptomatic and preserving pulpal vitality. Additionally, the formation of a dentin bridge immediately below the PC could be observed in the three molars treated. PC may be considered as an effective alternative for primary molar pulpotomies, at least in a short-term period. Randomized clinical trials with human teeth are required in order to determine the suitability of PC before unlimited clinical use can be recommended.

  3. Detecting flaws in Portland cement concrete using TEM horn antennae

    Science.gov (United States)

    Al-Qadi, Imad L.; Riad, Sedki M.; Su, Wansheng; Haddad, Rami H.

    1996-11-01

    To understand the dielectric properties of PCC and better correlate them with type and severity of PCC internal defects, a study was conducted to evaluate PCC complex permittivity and magnetic permeability over a wideband of frequencies using both time domain and frequency domain techniques. Three measuring devices were designed and fabricated: a parallel plate capacitor, a coaxial transmission line, and transverse electromagnetic (TEM) horn antennae. The TEM horn antenna covers the microwave frequencies. The measurement technique involves a time domain setup that was verified by a frequency domain measurement. Portland cement concrete slabs, 60 by 75 by 14 cm, were cast; defects include delamination, delamination filled with water, segregation, and chloride contamination. In this paper, measurements using the TEM horn antennae and the feasibility of detecting flaws at microwave frequency are presented.

  4. Sulfate resistance of ordinary Portland cement with fly ash

    Directory of Open Access Journals (Sweden)

    Irassar, Edgardo F.

    1989-03-01

    Full Text Available Low calcium fly ash has demonstrated to be an effective pozzolan to improve sulfate resistance of ordinary portland cement (type I. In this paper physico-chemical effects that produce this pozzolan in the mortar exposed to sulfate attack are studied. Dilution and dispersion affects are analyzed using mixes of cement with an inert mineral admixture. Mineralogical changes of mortar are studied using X-ray diffraction and the help of scanning electron microscope. The results show that fly ash delays mortar cracking phenomenon due to less content of unstable compounds in sulfate environment, greater available space to be occupied by expansive compounds and less CH present in the mortars.

    La ceniza volante de bajo contenido de óxido de calcio ha demostrado ser una efectiva puzolana para mejorar la resistencia a los sulfatos del cemento portland normal (CRN. En el presente trabajo se estudian los efectos físico-químicos que produce esta puzolana en el mortero expuesto al ataque de sulfatos. Se analizan los efectos de dilución y dispersión utilizando mezclas de cemento con una adición mineral inactiva. Los cambios mineralógicos del mortero se estudian con difracción de rayos X (DRX y la ayuda del microscopio electrónico. Los resultados indican que la ceniza volante retarda el fenómeno de fisuración del mortero debido a la menor cantidad de compuestos inestables en ambiente con sulfatos, el mayor espacio disponible para albergar a los compuestos expansivos y la disminución del CH presente en la mezcla.

  5. Influence of Calcium Sulfate State and Fineness of Cement on Hydration of Portland Cements Using Electrical Measurement

    Institute of Scientific and Technical Information of China (English)

    WEI Xiaosheng; LI Zongjin; XIAO Lianzhen; THONG Wangfai

    2006-01-01

    The influence of calcium sulfate state and fineness of cement on hydration of Portland cement was studied using electrical resistivity measurement. The bulk resistivity curve of the paste from the abnormal cement mainly with hemihydrate had a characteristic abnormal peak and rapid increase in early period. The resistivity measurement technique can be used to discriminate abnormal setting. For normal cement with gypsum, the increase in fineness of the Portland cement decreases the minimum resistivity due to a higher ionic concentration and increases the 24 hour resistivity due to a reduction in macroscopic pore size. Thesetting time, compressive strength, pore structure of pastes made from different cements were carried out to compare the influence of water to cement ratio, calcium sulfate state and fineness. It is found that the electrical and mechanical properties are strongly affected by the initial porosity, the presence of hemihydrate or gypsum, and the fineness of cement.

  6. Effect of three natural pozzolans in portland cement hydration

    Directory of Open Access Journals (Sweden)

    Rahhal, V.

    2003-03-01

    Full Text Available Natural pozzolans have been used since ancient times and continues to be used today. The chemistry and morphological composition of natural pozzolans and their particle size distribution allows classifying them as more or less reactive pozzolan. In this research several techniques have been used to study the influence of pozzolan on portland cement hydration as much as to evaluate the mechanical and durable properties of concretes, mortars and pastes containing pozzolans. This paper describes the effect of incorporating three natural pozzolans to two cements with very different mineralogical composition. The techniques used were: conduction calorimetry and Fratini test. Results proved that pozzolanic activity and the acceleration and retardation of hydration reaction depend on the mineralogical composition of the portland cernent used. Effects of dilution, stimulation, acceleration or retardation reactions, behavior into areas of heat dissipation and pozzolanic activity depend on the percentage of pozzolan used and the age in which it has been analyzed.

    El uso de las puzolanas naturales se remonta a la antigüedad, no obstante, actualmente continúa su utilización. La composición química y morfológica de las puzolanas naturales, sumado al tamaño de sus partículas, las califican como más o menos reactivas. En el estudio de las mismas, se han aplicado variadas técnicas para el análisis de sus interferencias en las reacciones de hidratación de los cementos portland; así como para la evaluación de las propiedades resistentes y duraderas que pueden conferirle a los hormigones, morteros o pastas de los que formen parte. Este trabajo versará sobre los efectos que produce la incorporación de tres puzolanas naturales a dos cementos portland de muy diferente composición mineralógica. Las técnicas aplicadas para su estudio han sido: la calorimetría de conducción y el ensayo de Fratini. Los resultados obtenidos permiten determinar

  7. Characteristics of Portland blast-furnace slag cement containing cement kiln dust and active silica

    Directory of Open Access Journals (Sweden)

    A. Abdel Rahman

    2016-09-01

    Full Text Available This investigation dealt with the effect of active silica, silica fume (SF or rice husk ash (RHA, on the mechanical and physico-chemical characteristics of the hardened blended cement pastes made of Portland blast-furnace slag cement (PSC containing cement kiln dust (CKD cured under normal conditions. Two blends made of PSC and CKD, improved by SF and two blends made of PSC and CKD improved by RHA were investigated. Hardened blended cement pastes were prepared from each cement blend by using water/cement ratio (W/C of 0.30 by weight and hydrated for various curing ages of 1, 3, 7, 28 and 90 days at the normal curing conditions under tap water at room temperature. Each cement paste was tested for its physico-chemical and mechanical characteristics; these characteristics include: compressive strength and kinetics of hydration. The phase composition of the formed hydration products was identified using X-ray diffraction (XRD and differential thermal analysis (DTA. It was found that the partial substitution of PSC by 10% and 15% of CKD is associated with an increase in the rate of hydration and a subsequent improvement of compressive strength of hardened PSC–CKD pastes. In addition, the replacement of PSC, in PSC–CKD blends, by 5% active silica was accompanied by further improvement of the physico-mechanical characteristics of the hardened PSC–CKD pastes.

  8. Influence of Portland Cement Class on the Corrosion Rate of Steel Reinforcement in Cement Mortar Caused by Penetrating Chloride and Sulfate from the Environment

    OpenAIRE

    Bikić, F.; Cacan, M.; Rizvanović, M.

    2013-01-01

    The influence of portland cement class on the corrosion rate of steel reinforcement in cement mortar caused by penetrating chloride or sulfate from the environment in already hardened cement mortar is investigated in this paper. Three classes of portland cement have been used for the tests, PC 35, PC 45 and PC 55. Cylindrical samples of cement mortar with steel reinfor- cement in the middle were treated 6 months at room temperature in the follow...

  9. Stabilization of chromium salt in ordinary portland cement

    Indian Academy of Sciences (India)

    Damir Barbir; Pero Dabić; Petar Krolo

    2012-12-01

    Ordinary Portland cement (OPC) samples containing the chromium salt have been investigated using differential microcalorimetry, conductometry and Fourier transform infrared spectroscopic analysis. The effect of chromium on OPC hydration was evaluated by continuous observing of early hydration. The microcalorimetrical results show that with increasing the share of chromium salt, heat maximums assume lower values and the occurrence of the maximum registered in the earlier hydration times. Conductometrical measurements show that with increasing addition of chromium salt, curve did not show any specific shape, immediate drop in specific conductivity is noticed and the maximum is reached earlier. This coincides with microcalorimetrical results. It can be concluded that the addition of chromium does not affect the mechanism of the hydration process, but it does affect the kinetic parameters and dynamics of the cement hydration process. It was found that chromium salt addition to the cement–water system is acceptable up to 2 wt.%. According to standard EN 196-3 for OPC, the beginning of binding time should occur after 60 minutes. Increased amount of chromium over 2 wt.% significantly accelerate the beginning of binding time and for the system it is not acceptable.

  10. The hardening of Portland cement studied by ? NMR stray-field imaging

    Science.gov (United States)

    Nunes, Teresa; Randall, E. W.; Samoilenko, A. A.; Bodart, P.; Feio, G.

    1996-03-01

    Hydration and hardening processes of Portland cement (type I) were studied by analysis of the one-dimensional projections (profiles) obtained periodically with the 0022-3727/29/3/044/img8 stray-field imaging technique over two days. The influence of additives, such as gypsum, in Portland cement (type IA) was also investigated. The decay of the signal intensity as a function of time was found to be bi-exponential for type I and mono-exponential for type IA.

  11. Structural study and crystallography of the major compound of anhydrous cement: tri-calcium silicate; Etude structurale et cristallographie du compose majoritaire du ciment anhydre: le silicate tricalcique

    Energy Technology Data Exchange (ETDEWEB)

    Noirfontaine, M.N. de

    2000-01-01

    Anhydrous (Portland) cement is mainly composed of a synthetic material, the clinker, whose major compound is tri-calcium silicate (Ca{sub 3}SiO{sub 5}), often referred as C{sub 3}S with the compact oxides notations, C = CaO et S = SiO{sub 2}. The polymorphism of C{sub 3}S, still not well known, is the main subject of the thesis. Various crystal structures (rhombohedral R, monoclinic M1, M2, M3 and triclinic T1, T2, T3) can be found, depending on temperature and impurities. The only known structures are T1, M1 and M3, involving large unit cells with an orientational disorder of silicate tetrahedra. The single crystal studies exhibit no clear relation between the various polymorphs. Starting from known results from literature single crystal experiments, we establish the metric and structural relations between the different structures. Averaged structures for the T1, M1 and M3 polymorphs are proposed, together with all the matrices of transformation between the unit cells. We also introduce new 1-D, 2-D, and 3-D structural units, which make easier the understanding of the structures of C{sub 3}S, with the result of a better description of the orientational disorder. The effects of impurities on the structure are discussed. In industrial clinkers, impurities stabilize mainly M1 and M3 monoclinic forms. We propose a space group (Pc) and two structural models (a superstructure and an approximate averaged structure) for the M1 form. All the models are validated on synthetic compounds (M3, M2, M1 et T1) and industrial clinkers analysed by X-Ray powder diffraction with Rietveld analysis. (author)

  12. Use of ancient copper slags in Portland cement and alkali activated cement matrices.

    Science.gov (United States)

    Nazer, Amin; Payá, Jordi; Borrachero, María Victoria; Monzó, José

    2016-02-01

    Some Chilean copper slag dumps from the nineteenth century still remain, without a proposed use that encourages recycling and reduces environmental impact. In this paper, the copper slag abandoned in landfills is proposed as a new building material. The slags studied were taken from Playa Negra and Púquios dumps, both located in the region of Atacama in northern Chile. Pozzolanic activity in lime and Portland cement systems, as well as the alkali activation in pastes with copper slag cured at different temperatures, was studied. The reactivity of the slag was measured using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), electrical conductivity and pH in aqueous suspension and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, copper slag-Portland cement mortars with the substitution of 25% (by weight) of cement by copper slag and alkali-activated slag mortars cured at 20 and 65 °C were made, to determine the compressive strength. The results indicate that the ancient copper slags studied have interesting binding properties for the construction sector.

  13. Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone

    DEFF Research Database (Denmark)

    Moesgaard, Mette; Poulsen, S.L.; Herfort, D.;

    2012-01-01

    This work investigates the hydration of blended Portland cement containing 30 wt.% Na2O-CaO-Al2O3-SiO2 (NCAS) glass particles either as the only supplementary cementitious material (SCM) or in combination with limestone, using 29Si MAS NMR, powder XRD, and thermal analyses. The NCAS glass...... of hydration. The hydrated glass contributes to the formation of the calcium-silicate-hydrate (C-S-H) phase, consuming a part of the Portlandite (Ca(OH)2) formed during hydration of the Portland cement. Furthermore, the presence of the glass and limestone particles, alone or in combination, results...... in an accelerated hydration for alite (Ca3SiO5), the main constituent of Portland cement. A higher degree of limestone reaction has been observed in the blend containing both limestone and NCAS glass as compared to the limestone – Portland mixture. This reflects that limestone reacts with a part of the alumina...

  14. Arsenic content in Portland cement: A literature review

    Directory of Open Access Journals (Sweden)

    Tenorio de Franca Talita

    2010-01-01

    Full Text Available Portland cement (PC is a hydraulic binding material widely used in the building industry. The main interest in its use in dentistry is focused on a possible alternative to mineral trioxide aggregate (MTA because PC is less expensive and is widely available. In dentistry, PC has been used in dental procedures such as pulpotomy, pulp capping, repair of root perforation and root-end filling. The purpose of this article is review the dental literature about the PC, its composition with special attention to arsenic content, properties, and application in dentistry. A bibliographic research was performed in Bireme, PubMed, LILACS and Scopus data bases looking for national and international studies about the PC composition, properties and clinical use. It was observed that PC has favorable biological properties very similar to those of MTA. The PC has shown good cell proliferation induction with formation of a monolayer cell, satisfactory inflammatory response, inhibitory effect of prostaglandin and antimicrobial effect. Studies have shown that PC is not cytotoxic, stimulates the apposition of reparative dentin and permits cellular attachment and growth. Regarding arsenic presence, its levels and release are low. PC has physical, chemical and biological properties similar to MTA. Arsenic levels and release are low, therefore, unable to cause toxic effects.

  15. Portland cement hydration in the presence of admixtures: black gram pulse and superplasticizer

    Directory of Open Access Journals (Sweden)

    Viveka Nand Dwivedi

    2008-12-01

    Full Text Available Effect of admixtures such as black gram pulse (BGP and sulfonated naphthalene based superplasticizer (SP on the hydration of Portland cement has been studied. The hydration characteristics of OPC in the presence of BGP and SP were studied with the help of non evaporable water content determinations, calorimetric method, Mössbauer spectroscopic and atomic force microscopic techniques. Results have shown that both BGP and SP get adsorbed at the surface of cement and its hydration products. The hydration of Portland cement is retarded in the presence of both the admixtures and nanosize hydration products are formed.

  16. Immediate and delayed solubility of mineral trioxide aggregate and Portland cement

    Directory of Open Access Journals (Sweden)

    Augusto Bodanezi

    2008-04-01

    Full Text Available This study investigated the solubility of mineral trioxide aggregate (MTA and Portland cement since its mixture until 672 hours, by means of two complimentary methods. Metal ring molds filled with the cements were covered with distilled water and, at each experimental time (3, 24, 72, 168, 336 and 672 hours, were weighed as soon as the plates in which the samples have been placed. Empty rings served as the control group (n=8. Mean weight gain and loss was determined and analyzed statistically by two-way ANOVA and Tukey's test for all pairwise comparisons. Only Portland cement showed less than 3% weight loss through 24 hours. Detached MTA residues were heavier than those of Portland cement over the 3 to 168 hours. The weight of MTA rings increased more than that of Portland rings within 672 hours (p=0.05. The findings of the present study indicate that, in an aqueous environment MTA is more soluble than Portland cement and exceeds the maximum weight loss considered acceptable by ISO 6876 standard (2001.

  17. Stabilization/solidification of selenium-impacted soils using Portland cement and cement kiln dust

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Deok Hyun, E-mail: dmoon10@hotmail.com [W.M. Keck Geoenvironmental Laboratory, Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Department of Environmental Engineering, Chosun University, Gwangju 501-759 (Korea, Republic of); Grubb, Dennis G. [W.M. Keck Geoenvironmental Laboratory, Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Schnabel Engineering, LLC, 510 East Gay Street, West Chester, PA 19380 (United States); Reilly, Trevor L. [W.M. Keck Geoenvironmental Laboratory, Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030 (United States)

    2009-09-15

    Stabilization/solidification (S/S) processes were utilized to immobilize selenium (Se) as selenite (SeO{sub 3}{sup 2-}) and selenate (SeO{sub 4}{sup 2-}). Artificially contaminated soils were prepared by individually spiking kaolinite, montmorillonite and dredged material (DM; an organic silt) with 1000 mg/kg of each selenium compound. After mellowing for 7 days, the Se-impacted soils were each stabilized with 5, 10 and 15% Type I/II Portland cement (P) and cement kiln dust (C) and then were cured for 7 and 28 days. The toxicity characteristic leaching procedure (TCLP) was used to evaluate the effectiveness of the S/S treatments. At 28 days curing, P doses of 10 and 15% produced five out of six TCLP-Se(IV) concentrations below 10 mg/L, whereas only the 15% C in DM had a TCLP-Se(IV) concentration <10 mg/L. Several treatments satisfied the USEPA TCLP best demonstrated available technology (BDAT) limits (5.7 mg/L) for selenium at pozzolan doses up to 10 times less than the treatments that established the BDAT. Neither pozzolan was capable of reducing the TCLP-Se(VI) concentrations below 25 mg/L. Se-soil-cement slurries aged for 30 days enabled the identification of Se precipitates by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX). XRD and SEM-EDX analyses of the Se(IV)- and Se(VI)-soil-cement slurries revealed that the key selenium bearing phases for all three soil-cement slurries were calcium selenite hydrate (CaSeO{sub 3}.H{sub 2}O) and selenate substituted ettringite (Ca{sub 6}Al{sub 2}(SeO{sub 4}){sub 3}(OH){sub 12}.26H{sub 2}O), respectively.

  18. Effect of Fine Steel Slag Powder on the Early Hydration Process of Portland Cement

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Hydration heat evolution, non-evaporative water, setting time and SEM tests were performed to investigate the effect of fine steel slag powder on the hydration process of Portland cement and its mechanism.The results show that the effect of fine steel slag powder on the hydration process of Portland cement is closely related to its chemical composition, mineral phases, fineness, etc.Fine steel slag powder retards the hydration of portland cement at early age.The major reason for this phenomenon is the relative high content of MgO , MnO2, P2 O5in steel slag, and MgO solid solved in C3 S contained in steel slag.

  19. Stabilization/solidification of selenium-impacted soils using Portland cement and cement kiln dust.

    Science.gov (United States)

    Moon, Deok Hyun; Grubb, Dennis G; Reilly, Trevor L

    2009-09-15

    Stabilization/solidification (S/S) processes were utilized to immobilize selenium (Se) as selenite (SeO(3)(2-)) and selenate (SeO(4)(2-)). Artificially contaminated soils were prepared by individually spiking kaolinite, montmorillonite and dredged material (DM; an organic silt) with 1000 mg/kg of each selenium compound. After mellowing for 7 days, the Se-impacted soils were each stabilized with 5, 10 and 15% Type I/II Portland cement (P) and cement kiln dust (C) and then were cured for 7 and 28 days. The toxicity characteristic leaching procedure (TCLP) was used to evaluate the effectiveness of the S/S treatments. At 28 days curing, P doses of 10 and 15% produced five out of six TCLP-Se(IV) concentrations below 10mg/L, whereas only the 15% C in DM had a TCLP-Se(IV) concentration phases for all three soil-cement slurries were calcium selenite hydrate (CaSeO(3).H(2)O) and selenate substituted ettringite (Ca(6)Al(2)(SeO(4))(3)(OH)(12).26H(2)O), respectively.

  20. The most suitable techiniques and methods to identify high alumina cement and based portland cement in concretes

    OpenAIRE

    Blanco, M. T.; Puertas, F; Vázquez, T.; de la Fuente, A

    1992-01-01

    Instrumental techniques are indicated and the most adequated methodologies for determining the nature of the binder in concretes are explained. These methods are: a) Determination of the Silicic Moduli through chemical analysis of the sample. This test reveáis very different valúes between cement portland based concrete and high alumina cement based concretes. b) X-ray diffraction. It is considered as the best method. In the present paper the main diffraction Unes corresponding to...

  1. Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone

    DEFF Research Database (Denmark)

    Moesgaard, M; Poulsen, Søren Lundsted; Herfort, D;

    2012-01-01

    M. MOESGAARD, S.L. POULSEN, D. HERFORT, M. STEENBERG, L.F. KIRKEGAARD, J. SKIBSTED, Y. YUE, Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone, Journal of the American Ceramic Society 95, 403 – 409 (2012).......M. MOESGAARD, S.L. POULSEN, D. HERFORT, M. STEENBERG, L.F. KIRKEGAARD, J. SKIBSTED, Y. YUE, Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone, Journal of the American Ceramic Society 95, 403 – 409 (2012)....

  2. Manganese substitutions into the portland cement clinker phases

    Directory of Open Access Journals (Sweden)

    Puertas, F.

    1989-06-01

    Full Text Available The effect of manganese substitution into the crystal structures of the main Portland cement clinker phases (3CaO.SiO2, 2CaO.SiO2, 3CaO.Al2O3, 2CaO.Fe2O3 y 4CaO.Al2O3.Fe2O3 has been studied by X-ray and analytical electron microscopy. In oxidizing conditions, the limit of solid solution in 3CaO.SiO2 is about 0.72 ±0.11% (wt, while in 2CaO.SiO2 is 1.53±0,12%(wt. Mn solid solubility on 3CaO.Al2O3structure, in oxidizing conditions is close to 0.78 ± 0,12% (wt. In identical atmosphere, the proportion of Mn in the ferrite phases (2CaO.Fe2O3 and 4CaO.Al2O3.Fe2O3 is 6.80 ± 0.87% (wt and 6.7% (wt, respectively. To each mentioned clinker phases a solid solution formula has been proposed. In these formula, the manganese substitutions and also the different oxidation states which this element can be introduced in those crystalline structure are defined.

    Se ha estudiado, por difracción de rayos X y microanálisis por espectroscopia de energías dispersivas, el efecto de la sustitución del manganeso en las estructuras cristalinas de las fases más importantes del clinker del cemento portland (3CaO.SiO2, 2CaO.SiO2, 3CaO.Al2O3, 2CaO.Fe2O3 y 4CaO.Al2O3.Fe2O3. En condiciones oxidantes, el límite de solubilidad sólida en 3CaO.SiO2 es del orden de 0,72 ± 0,11% en peso; mientras que en 2CaO.SiO2 es de 1,53 ±0,12% en peso. La solución sólida del Mn en la estructura del 3CaO.Al2O3, en condiciones oxidantes, es próxima al 0,78 ±0,12% en peso. En idéntica atmósfera, la proporción del Mn en las fases terríficas (2CaO.Fe2O3 y 4CaO.Al2

  3. Hydration study of ordinary portland cement in the presence of zinc ions

    Directory of Open Access Journals (Sweden)

    Monica Adriana Trezza

    2007-12-01

    Full Text Available Hydration products of Portland cement pastes, hydrated in water and in the presence of zinc ions were studied comparatively at different ages. Hydration products were studied by X ray diffractions (XRD and infrared spectroscopy (IR. Although IR is not frequently used in cement chemistry, it evidenced a new phase Ca(Zn(OH32. 2H2O formed during cement hydration in the presence of zinc. The significant retardation of early cement hydration in the presence of zinc is assessed in detail by differential calorimetry as a complement to the study carried out by IR and XRD, providing evidence that permits to evaluate the kinetic of the early hydration.

  4. Substitution of the clayey mineral component by lignite fly ash in portland cement clinker synthesis

    Directory of Open Access Journals (Sweden)

    Jovanović Nataša

    2006-01-01

    Full Text Available Fly ash from four power plants in Serbia (PP "Morava" - Svilajnac, PP "Kolubara" - Veliki Grijani, PP "Kostolac" - units B1 and B2 - Kostolac and PP "Nikola Tesla" - units A and B - Obrenovac was utilized as the starting raw component for Portland cement clinker synthesis. Limestone and quartz sand from the "Holcim - Serbia, a.d." cement factory were the other two starting raw components. Based on the chemical composition of the raw components and from the projected cement moduli, the amounts of raw components in the raw mixtures were calculated. Six different raw mixtures were prepared - each one consisted of limestone, sand and different fly ash. A raw mixture from the industrial production of the "Holcim - Serbia, a.d." cement factory was used as the reference material. The prepared raw mixtures were sintered in a laboratory furnace at 1400°C. The chemical and mineralogical compositions of the synthesized clinkers were determined. The characteristics of clinkers, based on fly ash, were compared to the characteristics of the industrial Portland cement clinker from the "Holcim - Serbia, a.d." cement factory. The results of the investigation showed that fly ash from power plants in Serbia can be suitable for Portland cement clinker synthesis.

  5. The Property of Portland Cement and its Employment in Dentistry: Review of the Literature

    Directory of Open Access Journals (Sweden)

    Antonio Vinícius Holanda BARBOSA

    2007-03-01

    Full Text Available Objective: The aim of the present study was to investigate the performance of the Portland cement when used as material in the dentistry. Methods: It was accomplished a bibliographical research using scientific goods published in national and international literature, which intended to evaluate the physical properties, chemical and biological behavior, as well as the antimicrobial activity of this product. In the selected article, the authors used methods of investigation in vitro and in vivo for study comparing the cement with materials consecrated in dentistry. Conclusion: In agreement with the consulted bibliography it was possible to ensure the similarity in the chemical composition between the Portland cement and the MTA, in the effectiveness of the sealing ability of the roads areas between the root canal and the periodontal tissue, satisfactory antimicrobial action, and demonstrate favorable biological properties, stimulating the deposition of the cement and inducing the reparative pulpar answer.

  6. Use of copper slag in the manufacture of Portland cement

    Directory of Open Access Journals (Sweden)

    Aquilar Elguézabal, A.

    2006-03-01

    Full Text Available Given its chemical and mineralogical characteristics, copper slag, a solid industrial by-product, may serve as a partial substitute for silica and hematite in raw mixes used to manufacture Portland cement clinker. The benefits of such substitution include lower production costs and energy savings. The effect of slag-containing raw mixes on the reactivity of the CaO-Si02-Al203-Fe203 system was studied at three temperatures (1,350, 1,400 and 1,450ºC. Four mixes were used: M-1 and M-2 prepared with conventional prime materials and M-3 and M-4, in which ignimbrite and hematite were substituted for slag. In M-3 the slag replaced 45.54% of the ignimbrite and 100% of the hematite, and in M-4 100% of the mineral iron. The samples were clinkerized at 1,350, 1,400 and 1,450ºC. At 1,400ºC, clinker M-3 was found to have 10.7% less free lime than M-1, while the level in M-4 it was 15.93% lower than in M-2. The presence of the main clinker phases was confirmed by X-ray diffraction, which also showed that adding slag during c/inker manufacture slightly improves raw mix burnability without generating new unwanted phases. Consequently, recovery in cement kilns would appear to be an economically and environmentally feasible alternative to coprocessing such waste, although the industrial use of slag depends on its heavy metal content.En acuerdo con las características químicas y mineralógicas de la escoria de cobre, este residuo sólido industrial puede ser utilizado en el proceso de fabricación de clínker Portland como sustituto parcial de los minerales de sílice y hematita en la formación de mezclas crudas cuyos beneficios serían: disminución de los costos de producción de mezclas crudas y del consumo calorífico. El efecto de la adición de la escoria en las mezclas crudas sobre la reactividad del sistema CaO-Si02-Al203-Fe20 3 se estudió en tres niveles de temperatura (1.350, 1.400 Y 1.450ºC. Se trabajó con cuatro mezclas crudas, M-1 y M

  7. Hydration Study of Ordinary Portland Cement in the Presence of Lead(II) Oxide

    OpenAIRE

    Barbir, D.; Dabić, P.; Krolo, P.

    2013-01-01

    The aim of this work was to investigate the effect of the addition of lead(II) oxide on hydration heat and specific conductivity of a CEM I Portland cement. The heat released during hydration was determined by differential microcalorimetry up to 48 hours of hydration and the specific conductivity by a digital conductometer. Thermogravimetric analysis was employed in the characterization of the cement structure. The hydration heat results show that the addition of lead(II) oxide affects the...

  8. Effects of Using Pozzolan and Portland Cement in the Treatment of Dispersive Clay

    OpenAIRE

    Vakili, A. H.; Selamat, M. R.; H. Moayedi

    2013-01-01

    Use of dispersive clay as construction material requires treatment such as by chemical addition. Treatments to dispersive clay using pozzolan and Portland cement, singly and simultaneously, were carried out in this study. When used alone, the optimum amount of pozzolan required to treat a fully dispersive clay sample was 5%, but the curing time to reduce dispersion potential, from 100% to 30% or less, was 3 month long. On the other hand, also when used alone, a 3% cement content was capable o...

  9. Portland cement hydration in the presence of admixtures: black gram pulse and superplasticizer

    OpenAIRE

    Viveka Nand Dwivedi; Shiva Saran Das; Nakshatra Bahadur Singh; Sarita Rai; Namdev Shriram Gajbhiye

    2008-01-01

    Effect of admixtures such as black gram pulse (BGP) and sulfonated naphthalene based superplasticizer (SP) on the hydration of Portland cement has been studied. The hydration characteristics of OPC in the presence of BGP and SP were studied with the help of non evaporable water content determinations, calorimetric method, Mössbauer spectroscopic and atomic force microscopic techniques. Results have shown that both BGP and SP get adsorbed at the surface of cement and its hydration products. Th...

  10. Galvanic corrosion of Mg-Zr fuel cladding and steel immobilized in Portland cement and geopolymer at early ages

    Science.gov (United States)

    Rooses, Adrien; Lambertin, David; Chartier, David; Frizon, Fabien

    2013-04-01

    Galvanic corrosion behaviour of Mg-Zr alloy fuel cladding and steel has been studied in Ordinary Portland cement and Na-geopolymer. Portland cements implied the worse magnesium corrosion performances due to the negative effects of cement hydrates, grinding agents and gypsum on the galvanic corrosion. Galvanic corrosion in Na-geopolymer paste remains very low. Silicates and fluoride from the geopolymer activation solution significantly improve the corrosion resistance of the magnesium alloy while coupling with a cathode.

  11. Comparative Analysis of Selected Physicochemical Properties of Pozzolan Portland and MTA-Based Cements.

    Science.gov (United States)

    Dorileo, Maura Cristiane Gonçales Orçati; Villa, Ricardo Dalla; Guedes, Orlando Aguirre; Aranha, Andreza Maria Fábio; Semenoff-Segundo, Alex; Bandeca, Matheus Coelho; Borges, Alvaro Henrique

    2014-01-01

    Physicochemical properties of pozzolan Portland cement were compared to ProRoot MTA and MTA BIO. To test the pH, the samples were immersed in distilled water for different periods of time. After the pH analysis, the sample was retained in the plastic recipient, and the electrical conductivity of the solution was measured. The solubility and radiopacity properties were evaluated according to specification 57 of the American National Standard Institute/American Dental Association (ANSI/ADA). The statistical analyses were performed using ANOVA and Tukey's test at a 5% level of significance. Pozzolan Portland cement exhibited pH and electrical conductivity mean values similar to those of the MTA-based cements. The solubilities of all tested materials were in accordance with the ANSI/ADA standards. Only the MTA-based cements met the ANSI/ADA recommendations for radiopacity. It might be concluded that the pH and electrical conductivity of pozzolan Portland cement are similar to and comparable to those of MTA-based cements.

  12. Model Analysis of Initial Hydration and Structure Forming of Portland Cement

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The auto efficiently hydration heat arrangement and the non-contacting electrical resistivity device were used to test the thermology effect and the resistivity variation of Portland cement hydration.The structure forming model of Portland cement initial hydration was established through the systematical experiments with different cements, the amount of mixing water and the chemical admixture. The experimental results show that, the structure forming model of cement could be divided into three stages, i e, solution-solution equilibrium period, structure forming period and structure stabilizing period. Along with the increase of mixing water, the time of inflexion appeared is in advance for thermal process of cement hydration and worsened for the structure forming process. Comparison with the control specimen, adding Na2SO4 makes the minimum critical point lower, the flattening period shorter and the growing slope after stage one steeper. So the hydration and structure forming process of Portland cement could be described more exactly by applying the thermal model and the structure-forming model.

  13. Rheological Properties of Very High-Strength Portland Cement Pastes: Influence of Very Effective Superplasticizers

    Directory of Open Access Journals (Sweden)

    Adriano Papo

    2010-01-01

    Full Text Available The influence of the addition of very effective superplasticizers, that are commercially available, employed for maximising the solid loading of very high-strength Portland cement pastes, has been investigated. Cement pastes were prepared from deionized water and a commercially manufactured Portland cement (Ultracem 52.5 R. Cement and water were mixed with a vane stirrer according to ASTM Standard C305. The 0.38 to 0.44 water/cement ratio range was investigated. Three commercial superplasticizing agents produced by Ruredil S.p.a. were used. They are based on a melamine resin (Fluiment 33 M, on a modified lignosulphonate (Concretan 200 L, and on a modified polyacrylate (Ergomix 1000. Rheological tests were performed at 25°C by using the rate controlled coaxial cylinder viscometer Rotovisko-Haake 20, system M5-osc., measuring device MV2P with serrated surfaces. The tests were carried out under continuous flow conditions. The results of this study were compared with those obtained in a previous article for an ordinary Portland cement paste.

  14. Steel foundry electric arc furnace dust management: stabilization by using lime and Portland cement.

    Science.gov (United States)

    Salihoglu, Guray; Pinarli, Vedat

    2008-05-30

    The purpose of this study was to determine an appropriate treatment for steel foundry electric arc furnace dust (EAFD) prior to permanent disposal. Lime and Portland cement (PC)-based stabilization was applied to treat the EAFD that contains lead and zinc above the landfilling limits, and is listed by USEPA as hazardous waste designation K061 and by EU as 10 02 07. Three types of paste samples were prepared with EAFD content varying between 0 and 90%. The first type contained the EAFD and Portland cement, the second contained the EAFD, Portland cement, and lime, and the third contained the EAFD and lime. All the samples were subjected to toxicity characteristics leaching procedure (TCLP) after an air-curing period of 28 days. pH changes were monitored and acid neutralization capacity of the samples were examined. Treatment effectiveness was evaluated in terms of reducing the heavy metal leachability to the levels below the USEPA landfilling criteria. An optimum composition for the EAFD stabilization was formulated as 30% EAFD +35% lime +35% Portland cement to achieve the landfilling criteria. The pH interval, where the solubility of the heavy metals in the EAFD was minimized, was found to be between 8.2 and 9.4.

  15. Microstructure engineering of Portland cement pastes and mortars through addition of ultrafine layer silicates

    DEFF Research Database (Denmark)

    Lindgreen, Holger; Geiker, Mette; Krøyer, Hanne;

    2008-01-01

    Pozzolanic submicron-sized silica fume and the non-pozzolanic micron- and nano-sized layer silicates (clay minerals) kaolinite, smectite and palygorskite have been used as additives in Portland cement pastes and mortars. These layer silicates have different particle shape (needles and plates), su...

  16. Prediction of compressive strength up to 28 days from microstructure of Portland cement

    DEFF Research Database (Denmark)

    Svinning, K.; Høskuldsson, Agnar; Justnes, H.

    2008-01-01

    The influence of the characteristics or the microstructure of Portland cement on compressive strength up to 28 days has been statistically investigated by application of partial least square (PLS) analysis. The main groups of characteristics were mineralogy and superficial microstructure represen...

  17. Physical and Thermodynamical Properties of Water Phases in Hardening Portland Cement Systems

    DEFF Research Database (Denmark)

    Hansen, T. Bæk

    The present study is devoted to the description of water phases in hardening portland cement paste systems containing a significant amount of micro-filler and having a low to moderate water/powder ratio. Emphasis has been placed on the early stages of the hardening process....

  18. Pulp tissue response to Portland cement associated with different radio pacifying agents on pulpotomy of human primary molars.

    Science.gov (United States)

    Marques, N; Lourenço Neto, N; Fernandes, A P; Rodini, C; Hungaro Duarte, M; Rios, D; Machado, M A; Oliveira, T

    2015-12-01

    The objective of this research was to evaluate the response of Portland cement associated with different radio pacifying agents on pulp treatment of human primary teeth by clinical and radiographic exams and microscopic analysis. Thirty mandibular primary molars were randomly divided into the following groups: Group I - Portland cement; Group II - Portland cement with iodoform (Portland cement + CHI3 ); Group III - Portland cement with zirconium oxide (Portland cement + ZrO2 ); and treated by pulpotomy technique (removal of a portion of the pulp aiming to maintain the vitally of the remaining radicular pulp tissue using a therapeutic dressing). Clinical and radiographic evaluations were recorded at 6, 12 and 24 months follow-up. The teeth at the regular exfoliation period were extracted and processed for histological analysis. Data were tested using statistical analysis with a significance level of 5%. The microscopic findings were descriptively analysed. All treated teeth were clinically and radiographically successful at follow-up appointments. The microscopic analysis revealed positive response to pulp repair with hard tissue barrier formation and pulp calcification in the remaining roots of all available teeth. The findings of this study suggest that primary teeth pulp tissue exhibited satisfactory biological response to Portland cement associated with radio pacifying agents. However, further studies with long-term follow-up are needed to determine the safe clinical indication of this alternative material for pulp therapy of primary teeth.

  19. A Thermoelectric Waste-Heat-Recovery System for Portland Cement Rotary Kilns

    Science.gov (United States)

    Luo, Qi; Li, Peng; Cai, Lanlan; Zhou, Pingwang; Tang, Di; Zhai, Pengcheng; Zhang, Qingjie

    2015-06-01

    Portland cement is produced by one of the most energy-intensive industrial processes. Energy consumption in the manufacture of Portland cement is approximately 110-120 kWh ton-1. The cement rotary kiln is the crucial equipment used for cement production. Approximately 10-15% of the energy consumed in production of the cement clinker is directly dissipated into the atmosphere through the external surface of the rotary kiln. Innovative technology for energy conservation is urgently needed by the cement industry. In this paper we propose a novel thermoelectric waste-heat-recovery system to reduce heat losses from cement rotary kilns. This system is configured as an array of thermoelectric generation units arranged longitudinally on a secondary shell coaxial with the rotary kiln. A mathematical model was developed for estimation of the performance of waste heat recovery. Discussions mainly focus on electricity generation and energy saving, taking a Φ4.8 × 72 m cement rotary kiln as an example. Results show that the Bi2Te3-PbTe hybrid thermoelectric waste-heat-recovery system can generate approximately 211 kW electrical power while saving 3283 kW energy. Compared with the kiln without the thermoelectric recovery system, the kiln with the system can recover more than 32.85% of the energy that used to be lost as waste heat through the kiln surface.

  20. Properties of expansive cements, made with Portland cement, gypsum and high alumina cement

    Directory of Open Access Journals (Sweden)

    Monfore, G. E.

    1966-03-01

    Full Text Available Not availableLos cementos expansivos se han desarrollado durante las tres décadas pasadas, principalmente por las investigaciones llevadas a cabo en Francia, URSS y Estados Unidos. Los cementos expansivos que fueron utilizados en los estudios de los cuales se da cuenta en el presente trabajo se obtuvieron mediante la mezcla de cemento Portland, cemento aluminoso y yeso. En las investigaciones se utilizaron morteros con los cuales se pudo determinar los efectos de la composición, tiempo y temperatura de curado sobre las resistencias, dilatación libre, retracción y desarrollo de resistencias en probetas pretensadas. Se hace una revisión sobre los estudios hechos con cementos expansivos y desarrollados en la Universidad de California. Las propiedades de taIes hormigones son, en términos generales, comparables a aquellos obtenidos con mezclas de cementos portland, cemento aluminoso y yeso. Es necesaria más información sobre pérdidas de tensión en los aceros y durabilidad de los hormigones autopretensados.

  1. Corrosion of steel bars in cracked concrete made with ordinary portland, slag and fly ash cements

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, T.U.; Yamaji, T.; Hamada, H. [Port and Harbor Research Inst., Ministry of Land, Infrastructure and Transport (Japan); Aoyama, T. [PS Corp. (Japan)

    2001-07-01

    A study was conducted in which the marine durability of ordinary portland cement, slag and fly ash cement was examined using 15 year old plain and reinforced concrete cylindrical specimens. The performance of these cements was then examined for pre-cracked reinforced concrete prism samples. The process of manufacturing cement emits huge amounts of carbon dioxide into the global atmosphere. Replacing a portion of the cement with by-products from the steel industry and thermal power plants (which are both huge emitters of carbon dioxide) can lower carbon dioxide emissions and also solve the disposal issue of slag and fly ash while increasing the long-term durability of concrete structures. In this study, concrete cylindrical specimens were made of ordinary portland cement, slag and fly ash cements. The specimens were 100 x 100 x 600 mm prisms of different types of cement. Water-to-cement ratios were 0.45 and 0.55. Both tap water and seawater were used as mixing water. The samples were exposed in tidal pools for 15 years to evaluate the compressive strength of the concrete, corrosion of the steel bars, and chloride-ion concentrations in the concrete. It was shown that, with the exception of fly ash cements, the compressive strength of most cements increased after 15 years of exposure compared to its 28 day strength. Type C slag cement demonstrated the best performance against chloride-ion at the surface of concrete made with slag and fly ash. Voids in the steel-concrete interface make it possible for corrosion pits to develop. The use of seawater as mixing water results in earlier strength development at 28 days and does not cause to the strength of the concrete to regress after 15-years of exposure, but it causes more corrosion of steel bars at a lower cover depth. Corrosion of steel bars is not an issue at deeper cover depths. 15 refs., 19 tabs., 13 figs.

  2. Effect of superplasticizers on the hydration kinetic and mechanical properties of Portland cement pastes

    Directory of Open Access Journals (Sweden)

    Safaa M.A. El-Gamal

    2012-04-01

    Full Text Available Hydration of ordinary Portland cement in the presence of two different types of superplasticizers namely sodium lignosulfonate (LS and naphthalene sulfonate-formaldehyde condensate (NSF was studied using different experimental techniques. Superplasticized ordinary Portland cement pastes were prepared using the values of standard water of consistency with different additions of each type of superplasticizers used. Pastes were hydrated for different time intervals under normal curing conditions. The results reveal that both superplasticizers increase the workability and reduce the standard water of consistency. This results in an improvement in the mechanical properties of superplasticized cement pastes at all ages of the hydration–hardening process. Naphthalene sulfonate-formaldehyde condensate was found to have the higher efficiency in improving the mechanical properties of the hardened pastes than that of sodium lignosulfonate superplasticizer.

  3. Mechanical properties of Portland cement and its constituents at the nano-level

    Science.gov (United States)

    French, Brent Alexander

    The following is a summary of research for a portion of the project titled Nano to Continuum Multi-Scale Modeling Techniques and Analysis For Cementitious Materials Under Dynamic Loading in association with North Carolina Agricultural & Technical State University and the US Army. This research investigates several attempts at creating a better Portland cement model at the atomistic level through molecular dynamics simulations. These models are modified to simulate damage to the basic cement structure, and are simulated using several combinations of forcefields and molecular dynamics tools. Experimental techniques such as nanoindentation, atomic force microscopy, and x-ray diffraction are applied to Portland cement samples to correlate mechanical properties among these techniques, as well as the numerical simulations.

  4. 76 FR 34252 - Notice Pursuant to the National Cooperative Research and Production Act of 1993; Portland Cement...

    Science.gov (United States)

    2011-06-13

    ... Cement Association Notice is hereby given that, on May 12, 2011, pursuant to Section 6(a) of the National Cooperative Research and Production Act of 1993, 15 U.S.C. 4301 et seq. (``the Act''), Portland Cement... specified circumstances. Specifically, Drake Cement, LLC, Scottsdale, AZ; Argos USA Corporation, Houston,...

  5. Feasibility study of the Portland cement industry waste for the reduction of energy consumption

    Energy Technology Data Exchange (ETDEWEB)

    Bernardo, Ana Carla de Souza Masselli; Junqueira, Mateus Augusto F. Chaib; Jorge, Ariosto Bretanha; Silva, Rogerio Jose da [Universidade Federal de Itajuba (UNIFEI), MG (Brazil). Institute of Mechanical Engineering]. E-mails: anacarlasz@unifei.edu.br; mateus_afcj@yahoo.com.br; ariosto.b.jorge@unifei.edu.br; rogeriojs@unifei.edu.br

    2008-07-01

    The Portland cement industry demand a high specific consumption of energy for the production of the clinker. The energy consumption for clinker production varies between 3000 and 5300 kJ/kg of produced clinker. The clinker is produced by blending of different raw materials in order t o achieve precise chemical proportions of lime, silica, alumina and iron in the finished product and by burning them at high temperatures. The Portland cement is a mixture of clinker, gypsum and other materials. Due to need of high temperatures, tradition ally the fuels used in the cement industry are mineral coal, fuel oil, natural gas and petroleum coke. The fuel burning in high temperature leads to the formation of the pollutant thermal NOx. The level of emissions of this pollutant is controlled by environmental law, thus the formation of pollutants in process need be controlled. Moreover, industrial waste has been used by Portland cement industries as a secondary fuel through a technique called co -processing. Materials like waste oils, plastics, waste tyres and sewage sludge are often proposed as alternative fuels for the cement industry. The residues can be introduced as secondary fuel or secondary raw material. For energy conservation in the process, mineralizers are added during the process production of the clinker. The mineralizers promote certain reactions which decrease the temperature in the kiln and improve the quality of the clinker. The adequate quantity of constituents in production process is complex, for maintain in controlled level, the quality of final product, the operational conditions of kiln, and the pollutant emissions. The purpose of the present work is to provide an analysis of an optimal production point through of the optimization technique considering, the introduction of the fuels, industrial wastes as secondary fuels, and raw materials, for the reduction of energy in the process of Portland cement production. (author)

  6. Characterization and utilization of cement kiln dusts (CKDs) as partial replacements of Portland cement

    Science.gov (United States)

    Khanna, Om Shervan

    The characteristics of cement kiln dusts (CKDs) and their effects as partial replacement of Portland Cement (PC) were studied in this research program. The cement industry is currently under pressure to reduce greenhouse gas (GHG) emissions and solid by-products in the form of CKDs. The use of CKDs in concrete has the potential to substantially reduce the environmental impact of their disposal and create significant cost and energy savings to the cement industry. Studies have shown that CKDs can be used as a partial substitute of PC in a range of 5--15%, by mass. Although the use of CKDs is promising, there is very little understanding of their effects in CKD-PC blends. Previous studies provide variable and often conflicting results. The reasons for the inconsistent results are not obvious due to a lack of material characterization data. The characteristics of a CKD must be well-defined in order to understand its potential impact in concrete. The materials used in this study were two different types of PC (normal and moderate sulfate resistant) and seven CKDs. The CKDs used in this study were selected to provide a representation of those available in North America from the three major types of cement manufacturing processes: wet, long-dry, and preheater/precalciner. The CKDs have a wide range of chemical and physical composition based on different raw material sources and technologies. Two fillers (limestone powder and quartz powder) were also used to compare their effects to that of CKDs at an equivalent replacement of PC. The first objective of this study was to conduct a comprehensive composition analysis of CKDs and compare their characteristics to PC. CKDs are unique materials that must be analyzed differently from PC for accurate chemical and physical analysis. The present study identifies the chemical and physical analytical methods that should be used for CKDs. The study also introduced a method to quantify the relative abundance of the different

  7. A Comparative Study Between the Early Stages Hydration of a High Strength and Sulphate Resistant Portland Cement and the Type II F Portland Cement Through Non Conventional Differential Thermal Analysis and Thermogravimetry

    OpenAIRE

    Neves Junior,Alex; Viana,Marcelo Mendes; Dweck,Jo; Toledo Filho,Romildo Dias

    2015-01-01

    This work presents a study, which compares the early stages of hydration of a High Initial Strength and Sulphate Resistant Portland Cement (HIS SR PC) with those of Type II F Portland Cement (PC II), by Non-Conventional Differential Thermal Analysis (NCDTA) within the first 24 hours of hydration. Water/cement (w/c) ratios equal to 0.5, 0.6 and 0.66 were used to prepare the pastes. The hydration of these two types of cement was monitored on real time by NCDTA curves, through the thermal effect...

  8. Development of the Portland cement slurries with diatomaceous earth to the oil industry; Desenvolvimento de pastas de cimento Portland com adicao de diatomita para a industria do petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Brito, Roseane A; Melo, Dulce M.A.; Martinelli, Antonio E.; Simao, Cristina A.; Paiva, Maria D.M. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Melo, Marcus A.F. [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

    2004-07-01

    The class-G Portland cement has been used with success in oil well cementing. The material is usually shipped to the Northeast Brazil, because the only plant that manufactures class-G is located in Cantagalo/RJ. The present work investigates the influence of the partial substitution of Portland cement by diatomaceous earth, aiming at reducing the costs in oil well cementing, improving the slurry properties and using local raw material. The diatomaceous earth has pozzolanic properties and can be used as extenders of cement slurries. This properties added to the lower cost and availability of this material in Northeast Brazil, make the diatomaceous earth a candidate material to produce light cements, to well conditions in advanced phases of production. It were evaluated the rheological properties of the slurries (at 25 and 52 deg C), volume of free water, compressive strength after curing for 8, 24 and 48 h at 38 deg C, and consistometry tests. The results show that the diatomaceous earth maintain the viscosity values and gel force suitable for use in oil well cementing. No free water was observed in the formulations. It was also verified that the compressive strength of slurries hardened with diatomaceous earth is similar to those with only Portland cement and that the minimum compressive strength of 300 psi, after curing for 8 h was reached. The thickening time was longer than the average value and the application value. (author)

  9. DSC and TG Analysis of a Blended Binder Based on Waste Ceramic Powder and Portland Cement

    Science.gov (United States)

    Pavlík, Zbyšek; Trník, Anton; Kulovaná, Tereza; Scheinherrová, Lenka; Rahhal, Viviana; Irassar, Edgardo; Černý, Robert

    2016-03-01

    Cement industry belongs to the business sectors characteristic by high energy consumption and high {CO}2 generation. Therefore, any replacement of cement in concrete by waste materials can lead to immediate environmental benefits. In this paper, a possible use of waste ceramic powder in blended binders is studied. At first, the chemical composition of Portland cement and ceramic powder is analyzed using the X-ray fluorescence method. Then, thermal and mechanical characterization of hydrated blended binders containing up to 24 % ceramic is carried out within the time period of 2 days to 28 days. The differential scanning calorimetry and thermogravimetry measurements are performed in the temperature range of 25°C to 1000°C in an argon atmosphere. The measurement of compressive strength is done according to the European standards for cement mortars. The thermal analysis results in the identification of temperature and quantification of enthalpy and mass changes related to the liberation of physically bound water, calcium-silicate-hydrates dehydration and portlandite, vaterite and calcite decomposition. The portlandite content is found to decrease with time for all blends which provides the evidence of the pozzolanic activity of ceramic powder even within the limited monitoring time of 28 days. Taking into account the favorable results obtained in the measurement of compressive strength, it can be concluded that the applied waste ceramic powder can be successfully used as a supplementary cementing material to Portland cement in an amount of up to 24 mass%.

  10. Spectroscopic and microscopic characterization of portland cement based unleached and leached solidified waste

    Science.gov (United States)

    Salaita, Ghaleb N.; Tate, Philip H.

    1998-05-01

    In this study, portland cement based solidified/stabilized (S/S) waste and a cement-only control were studied before and after leaching. The solidified waste samples were prepared from a mix of organic-containing industrial waste sludge and portland cement. Toxicity characterization leaching procedure (TCLP) was the leaching test employed. The samples were studied using multi-surface analytical techniques including XPS, SIMS, XRD, FE-SEM and EDS. The data obtained from the various techniques show that leaching does not measurably affect the morphology or composition of the solidified waste sample. However, subtle changes in the composition of the cement control sample were observed. While the concentration of the elements observed on the surface of leached and unleached waste samples by XPS are very similar (except for Mg, Na and N), study of the corresponding cement samples exhibit differences in the level of C, Si, S, and Ca. The unleached cement sample shows lower levels of C and Si, but higher levels of O, S, Ca and Mg, indicating that leaching alters the cement sample. EDS analyses of the elemental composition of the bulk of the leached and unleached waste samples are similar, and also are similar for the leached and unleached cement samples, indicating that under the conditions of the TCLP test, leaching has no effect on the bulk. The high level of Ca present on the surface of the solidified waste indicates entrapment of the waste by the cement. The information and results obtained show that the surface analytical techniques used in this work, when combined with environmental wet methods, can provide a more complete picture of the concentration, chemical state and immobility of solidified waste.

  11. Anti-Crack Performance of Low-Heat Portland Cement Concrete

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The properties of low-heat Portland cement concrete(LHC) were studied in detail. The experimental results show that the LHC concrete has characteristics of a higher physical mechanical behavior, deformation and durability. Compared with moderate-heat Portland cement(MHC), the average hydration heat of LHC concrete is reduced by about 17.5%. Under same mixing proportion, the adiabatic temperature rise of LHC concrete was reduced by 2℃-3℃,and the limits tension of LHC concrete was increased by 10×10-6-15×10-6 than that of MHC. Moreover, it is indicated that LHC concrete has a better anti-crack behavior than MHC concrete.

  12. Performance Characteristics of Waste Glass Powder Substituting Portland Cement in Mortar Mixtures

    Science.gov (United States)

    Kara, P.; Csetényi, L. J.; Borosnyói, A.

    2016-04-01

    In the present work, soda-lime glass cullet (flint, amber, green) and special glass cullet (soda-alkaline earth-silicate glass coming from low pressure mercury-discharge lamp cullet and incandescent light bulb borosilicate glass waste cullet) were ground into fine powders in a laboratory planetary ball mill for 30 minutes. CEM I 42.5N Portland cement was applied in mortar mixtures, substituted with waste glass powder at levels of 20% and 30%. Characterisation and testing of waste glass powders included fineness by laser diffraction particle size analysis, specific surface area by nitrogen adsorption technique, particle density by pycnometry and chemical analysis by X-ray fluorescence spectrophotometry. Compressive strength, early age shrinkage cracking and drying shrinkage tests, heat of hydration of mortars, temperature of hydration, X-ray diffraction analysis and volume stability tests were performed to observe the influence of waste glass powder substitution for Portland cement on physical and engineering properties of mortar mixtures.

  13. Comparative Analysis of Selected Physicochemical Properties of Pozzolan Portland and MTA-Based Cements

    OpenAIRE

    Dorileo, Maura Cristiane Gonçales Orçati; Villa, Ricardo Dalla; Guedes, Orlando Aguirre; Aranha, Andreza Maria Fábio; Semenoff-Segundo, Alex; Bandeca, Matheus Coelho; Borges, Alvaro Henrique

    2014-01-01

    Physicochemical properties of pozzolan Portland cement were compared to ProRoot MTA and MTA BIO. To test the pH, the samples were immersed in distilled water for different periods of time. After the pH analysis, the sample was retained in the plastic recipient, and the electrical conductivity of the solution was measured. The solubility and radiopacity properties were evaluated according to specification 57 of the American National Standard Institute/American Dental Association (ANSI/ADA). Th...

  14. Recycling of porcelain tile polishing residue in portland cement: hydration efficiency.

    Science.gov (United States)

    Pelisser, Fernando; Steiner, Luiz Renato; Bernardin, Adriano Michael

    2012-02-21

    Ceramic tiles are widely used by the construction industry, and the manufacturing process of ceramic tiles generates as a major residue mud derived from the polishing step. This residue is too impure to be reused in the ceramic process and is usually discarded as waste in landfills. But the analysis of the particle size and concentration of silica of this residue shows a potential use in the manufacture of building materials based on portland cement. Tests were conducted on cement pastes and mortars using the addition of 10% and 20% (mass) of the residue. The results of compressive strength in mortars made up to 56 days showed a significant increase in compressive strength greater than 50%. The result of thermogravimetry shows that portlandite is consumed by the cement formed by the silica present in the residue in order to form calcium silicate hydrate and featuring a pozzolanic reaction. This effect improves the performance of cement, contributes to research and application of supplementary cementitious materials, and optimizes the use of portland cement, reducing the environmental impacts of carbon dioxide emissions from its production.

  15. Effect of blastfurnace slag addition to Portland cement for cationic exchange resins encapsulation

    Directory of Open Access Journals (Sweden)

    Stefan L.

    2013-07-01

    Full Text Available In the nuclear industry, cement-based materials are extensively used to encapsulate spent ion exchange resins (IERs before their final disposal in a repository. It is well known that the cement has to be carefully selected to prevent any deleterious expansion of the solidified waste form, but the reasons for this possible expansion are not clearly established. This work aims at filling the gap. The swelling pressure of IERs is first investigated as a function of ions exchange and ionic strength. It is shown that pressures of a few tenths of MPa can be produced by decreases in the ionic strength of the bulk solution, or by ion exchanges (2Na+ instead of Ca2+, Na+ instead of K+. Then, the chemical evolution of cationic resins initially in the Na+ form is characterized in CEM I (Portland cement and CEM III (Portland cement + blastfurnace slag cements at early age and an explanation is proposed for the better stability of CEM III material.

  16. CALCIUM ORTHOPHOSPHATES HYDRATES: FORMATION, STABILITY AND INFLUENCE ON STANDARD PROPERTIES OF PORTLAND CEMENT

    Directory of Open Access Journals (Sweden)

    Kaziliunas A.

    2013-12-01

    Full Text Available Preparation of phosphogypsum to produce the binders requires a much higher input than preparation of natural gypsum stone. This makes it uncompetitive material. The investigations presented therein are meant to reduce this input by looking for the ways of rendering impurities harmless. Soluble acid orthophosphates are the main harmful impurity of phosphogypsum. The studies show that dry insoluble calcium orthophosphates hydrates (1.09 % and 2.18 % P2O5 in gypsum have little effect on W/C, setting times and soundness of Portland cement pastes. Insoluble calcium orthophosphates hydrates {CaHPO4∙2H2O, Ca8(HPO42(PO44∙5H2O and Ca9(HPO4(PO45(OH∙4H2O} formed in acidic medium (pH = 4.2 - 5.9 have been destroyed in alkaline medium and reduce standard compressive strength of cement up to 28 %. Calcium orthophosphates hydrates of hydroxyapatite group are stable in alcaline medium, while in dry state they reduce the standard compressive strength of cement until 10 %, but their suspensions prolong setting times of Portland cement as soluble orthophosphates – 2 - 3 times. Alkalis in cement increase pH of paste, but do not change the process of formation of calcium orthophosphates hydrates of hydroxyapatite group: it takes place through an intermediate phase - CaHPO4·2H2O, whose transformation into apatite lasts for 2 - 3 months.

  17. Ageing of portland cement concrete cured under moist conditions

    NARCIS (Netherlands)

    Yu, Z.; Ye, G.; Van Breugel, K.; Chen, W.

    2014-01-01

    Deterioration of microstructure in cement concrete will cause changes in the transport properties of the concrete. Transport properties at different ages of the concrete provide information about the microstructural changes of the material. A way to measure the transport properties, i.e. the chlorid

  18. Comparative SEM study of the marginal adaptation of white and grey MTA and Portland cement.

    Science.gov (United States)

    Bidar, Maryam; Moradi, Saeed; Jafarzadeh, Hamid; Bidad, Salma

    2007-04-01

    The use of a suitable substance that prevents egress of potential contaminants into the periapical tissues is important in endodontic surgery. The aim of the present study was to compare the marginal adaptation of three root-end filling materials (white mineral trioxide aggregate (MTA), grey MTA and Portland cement), using scanning electron microscopy. Seventy-five single-rooted extracted human teeth were used. The canals were instrumented and filled with gutta-percha. Following root-end resection and cavity preparation, root-end cavities were filled with white MTA, grey MTA or Portland cement. Using a diamond saw, roots were longitudinally sectioned into two halves. Under scanning electron microscopy, the gaps between the material and dentinal wall were measured. The data were analysed using Kruskal-Wallis test. The mean of the gap in grey MTA, white MTA and Portland cement was 211.6, 349 and 326.3 microm, respectively. The results indicate that the gap between grey MTA and the dentinal wall is less than other materials, but there was no significant difference between the materials tested in this study (P > 0.05).

  19. The effects of utilizing silica fume in Portland Cement Pervious Concrete

    Science.gov (United States)

    Mann, Daniel Allen

    Silica fume has long been used as a supplementary cementing material to provide a high density, high strength, and durable building material. Silica fume has a particle size a fraction of any conventional cement, which allows it to increase concrete strength by decreasing the porosity especially near the aggregates surface. Because Portland Cement Pervious Concrete (PCPC) has a smaller bond area between aggregate and paste, silica fume has significant impacts on the properties of the PCPC. The research in this paper studies the workability of a cement paste containing silica fume in addition to analyzing the results of testing on Portland Cement Pervious Concrete mixtures that also contained silica fume. Testing conducted included a study of the effects of silica fume on cement's rheological properties at various dosage rates ranging from zero to ten percent by mass. It was determined that silica fume has negligible effects on the viscosity of cement paste until a dosage rate of five percent, at which point the viscosity increases rapidly. In addition to the rheological testing of the cement paste, trials were also conducted on the pervious concrete samples. Sample groups included mixes with river gravel and chipped limestone as aggregate, washed and unwashed, and two different void contents. Workability tests showed that mixtures containing a silica fume dosage rate of 5 percent or less had comparable or slightly improved workability when compared to control groups. Workability was found to decrease at a 7 percent dosage rate. Samples were tested for compressive strength at 7 and 28 days and splitting tensile strength at 28 days. It was found in most sample groups, strength increased with dosage rates of 3 to 5 percent but often decreased when the dosage reached 7 percent. Abrasion testing showed that both samples containing washed aggregate and samples containing silica fume exhibited a reduced mass loss.

  20. Effects of Using Pozzolan and Portland Cement in the Treatment of Dispersive Clay

    Directory of Open Access Journals (Sweden)

    A. H. Vakili

    2013-01-01

    Full Text Available Use of dispersive clay as construction material requires treatment such as by chemical addition. Treatments to dispersive clay using pozzolan and Portland cement, singly and simultaneously, were carried out in this study. When used alone, the optimum amount of pozzolan required to treat a fully dispersive clay sample was 5%, but the curing time to reduce dispersion potential, from 100% to 30% or less, was 3 month long. On the other hand, also when used alone, a 3% cement content was capable of reducing dispersion potential to almost zero percent in only 7 days; and a 2% cement content was capable of achieving similar result in 14 days. However, treatment by cement alone is costly and could jeopardize the long term performance. Thus, a combined 5% pozzolan and 1.5% cement content was found capable of reducing dispersion potential from 100% to zero percent in 14 days. The results indicate that although simultaneous treatment with pozzolan and cement would extend the required curing time in comparison to treatment by cement alone of a higher content, the task could still be carried out in a reasonable period of curing time while avoiding the drawbacks of using either pozzolan or cement alone.

  1. Long-term Performance of Moderate Heat Portland Cement with Double-expansive Sources

    Institute of Scientific and Technical Information of China (English)

    YE Qing; CHEN Huxing; KONG Deyu; WANG Shangxian; LOU Zonghan

    2007-01-01

    The long-term performance of moderate heat Portland cement with double-expansive sources (DE cement) in the system of high MgO clinker and gypsum was studied by XRD, SEM/EDAX and test methods for strength and expansion of cement. Results indicate that the periclase particle, whose size was 5-7.5 μm in DE cement clinker containing 4.8 % MgO, existed individually. The periclase hydration in hardened DE cement paste started at about 60 days and completed up to 2 000 days, and ettringite in the paste was stable from 3 days to 2 000 days. Under the conditions of 4.5%-5.0 % MgO in clinker and 2.8%-3.4 %SO3 in cement,ettringite expansion and brucite expansion in DE cement paste had a continuity, entirety and stability. At the ages of 90, 365, 730 and 2 000 days the expansion of the paste reached 0.07%-0.11%, 0.16%-0.21%, 0.21%-0.27% and 0.29%-0.38 %, respectively. The results suggest that by using this cement in mass concrete it may compensate its temperature shrinkage and autogenous shrinkage to some extent.

  2. Effects of using pozzolan and Portland cement in the treatment of dispersive clay.

    Science.gov (United States)

    Vakili, A H; Selamat, M R; Moayedi, H

    2013-01-01

    Use of dispersive clay as construction material requires treatment such as by chemical addition. Treatments to dispersive clay using pozzolan and Portland cement, singly and simultaneously, were carried out in this study. When used alone, the optimum amount of pozzolan required to treat a fully dispersive clay sample was 5%, but the curing time to reduce dispersion potential, from 100% to 30% or less, was 3 month long. On the other hand, also when used alone, a 3% cement content was capable of reducing dispersion potential to almost zero percent in only 7 days; and a 2% cement content was capable of achieving similar result in 14 days. However, treatment by cement alone is costly and could jeopardize the long term performance. Thus, a combined 5% pozzolan and 1.5% cement content was found capable of reducing dispersion potential from 100% to zero percent in 14 days. The results indicate that although simultaneous treatment with pozzolan and cement would extend the required curing time in comparison to treatment by cement alone of a higher content, the task could still be carried out in a reasonable period of curing time while avoiding the drawbacks of using either pozzolan or cement alone.

  3. Contribution to Portland cement hemihydrite and gypsum content determination

    Directory of Open Access Journals (Sweden)

    Moreno Arús, F.

    1974-09-01

    Full Text Available Not availableLa mayoría de los técnicos de cemento eceptan que las anormalidades del fraguado, conocidas como "falso fraguado" en el cemento portland, se deben primordialmente a la presencia de yeso parcialmente deshidratado (SO4Ca 1/2H2O. Si el clinker que se muele está enriquecido en cal libre, o la temperatura del molino es elevada (superior a los 110 ºC o hay escasa ventilación de éste, se llega a originar una parcial deshidratación del yeso, que se mantiene durante el proceso de ensilado y origina las anormalidades del fraguado anteriormente referidas. Por esta razón creemos muy importante el poder conocer el grado de deshidratación en que se encuentra el yeso en un cemento.

  4. Hydration of portland cement, natural zeolite mortar in water and sulphate solution

    Directory of Open Access Journals (Sweden)

    Janotka, I.

    2003-03-01

    Full Text Available The objective of this paper is to characterise sulphate resistance of mortars made from ordinary Portland cement ( PC and Portland-pozzolan cement with 35 wt.% of zeolite addition (zeolite-blended cement-ZBC . Mortars with two different cement types were tested in water and 5% sodium sulphate solution for 720 days. A favourable effect of zeolite on increased sulphate resistance of the cement is caused by decrease in free Ca(OH2 content of the mortar There is not sufficient of Ca(OH2 available for reacting with the sulphate solution to form voluminous reaction products. A decreased C3A, content due to 35 wt.% replacement of PC by zeolite is the next pronounced factor improving resistance of the mortar with such blended cement.

    El objetivo de este trabajo ha sido estudiar la resistencia a los sulfatos de morteros preparados con cemento portland ordinario (PC y cemento portland puzolánico, con un 35% en peso de zeolita (zeolite-blended cement (ZBC. Ambos tipos de morteros fueron conservados en agua y en una disolución de sulfato sódico al 5% durante 720 días. Se observó una mayor resistencia a los sulfatos en el mortero preparado con el cemento que contenía zeolita debido a su menor contenido en Ca(OH2. No hay cantidad suficiente de Ca(OH2 para que se produzca la reacción de los constituyentes de la pasta con la disolución de sulfato sódico y formar así productos de naturaleza expansiva. La disminución en el contenido de C,3A, debida a la sustitución de un 35% en peso de PC por zeolita, es el factor más determinante en el aumento de la resistencia del mortero en los cementos con adición.

  5. Biocompatibility assessment of modified Portland cement in comparison with MTA® : In vivo and in vitro studies

    Directory of Open Access Journals (Sweden)

    I Khalil

    2012-01-01

    Full Text Available Aim: The aim of our study is to elaborate a new cement based on Portland cement (PC, Modified Portland Cement (MPC with modified chemical and physical properties that allow easier clinical manipulation and faster setting time than MTA® and then to evaluate its cytotoxicity in vitro and its biocompatibility in vivo in comparison with MTA® . Materials and Methods: Elaboration of MPC: Portland cement powder slenderly grinded to homogenize the particles, mixed with a radiopaque element and a setting time accelerator. A comparative in vitro study (MTS test of the toxic effect of MTA® and MPC with culture isolated from the calvaria of 18-day-old fetal Swiss OF1 mice are done. A comparative in vivo study of the biocompatibility of MTA® and MPC: Under general anaesthesia, three holes (2.5 mm were made in both the left and right femurs of six White New Zealand rabbits. In the first hole MPC is placed, in the second MTA® and the third one is left empty (negative control group. Three weeks after implantation, two rabbits are sacrificed, then two other rabbits over six weeks and the last two after twelve weeks. The neck of the femur is trimmed and prepared for undecalcified histological studies. Mann-Whitney test was used to analyze the results. Results: The cell viability test according to the morphological observations suggested the biocompatibility of the two biomaterials tested. The in vivo test showed similar biocompatibility between MTA® and MPC. Bone healing and minimal inflammatory response adjacent to MTA® and MPC implants were observed at all experimental periods (3, 6 and 12 weeks, suggesting that both materials are well tolerated. Conclusion: This pilot comparative study of MTA® and MPC showed no or very limited toxic effects of both cements in vitro and similar biocompatibility in vivo. However, additional in vivo and clinical studies should be done on MPC before it can be introduced in our clinical practice.

  6. Spent FCC catalyst for improving early strength Portland cement

    OpenAIRE

    Borrachero Rosado, María Victoria; Monzó Balbuena, José Mª; Paya Bernabeu, Jorge Juan; Vunda, Christian; VELÁZQUEZ RODRÍGUEZ, SERGIO; Soriano Martinez, Lourdes

    2014-01-01

    Spent fluid catalytic cracking (FCC) catalyst from the petrol industry has proven to be a very active pozzolanic material. This behavior leads to an additional increase in the strength of the mortar that contains this catalyst. Pozzolanic effects tend to be considered for periods above three days, whereas in shorter times, the influence of pozzolan is usually negligible. The reactivity of FCC is so high, however, that both pozzolanic effects and acceleration of cement hydration are evident in...

  7. INVESTIGATING EFFECTS OF INTRODUCTION OF CORNCOB ASH INTO PORTLAND CEMENTS CONCRETE: MECHANICAL AND THERMAL PROPERTIES

    Directory of Open Access Journals (Sweden)

    Antonio Price

    2014-01-01

    Full Text Available The purpose of this study was to evaluate the benefits of replacing Ordinary Portland Cement (OPC with Corncob Ash (CCA blended cements. The cement industry contributes considerable amount of Carbon Dioxide (CO2 emissions into the atmosphere. The main contribution of CO2 emissions from cement production results from the process of creating Calcium Oxide (CaO from limestone (CaCO3 commonly known as the calcination process. Blending OPC with a pozzolanic material will assist in the reduction of CO2 emissions due to calcination as well as enhance the quality of OPC. There are various pozzolanic materials such as fly ash, rice husk, silica fume and CCA that could be promising partial replacement for OPC. In this study, CCA will serve as the primary blending agent with OPC. An experiment was performed to designate an appropriate percentage replacement of CCA that would comply with specific standards of cement production. The experimental plan was designed to analyze compressive strength, workability and thermal performance of various CCA blended cements. The data from the experiment indicates that up to 10% CCA replacement could be used in cement production without compromising the structural integrity of OPC. In addition, it was found that the compressive strength and workability of the resulting concrete could be improved when CCA is added to the mixtures. Furthermore, it was shown that the introduction of 10% CCA can lead to significant reduction in thermal conductivity of the mixture.

  8. Reaction of rat subcutaneous tissue to mineral trioxide aggregate and Portland cement: A secondary level biocompatibility test

    Directory of Open Access Journals (Sweden)

    P Karanth

    2013-01-01

    Full Text Available Objectives: This secondary-level animal study was conducted to assess and compare the subcutaneous tissue reaction to implantation of white mineral trioxide aggregate (MTA and white Portland cement. Study Design: Polyethylene tubes filled with either freshly mixed white MTA (Group I or white Portland cement (Group II were implanted subcutaneously into 12 Wistar Albino rats. Each animal also received an empty polyethylene tube as the control (Group III. After 7, 14, 21 and 30 days, the implants, together with surrounding tissues were excised. Two pathologists blinded to the experimental procedure, evaluated sections taken from the biopsy specimens for the severity of the inflammatory response, calcification and the presence and thickness of fibrous capsule surrounding the implant. Statistical analysis was performed using the Cross-tabs procedure, Univariate analysis of the variance two-way and the Pearson product moment correlation to assess inter-rater variability between the two evaluators. Results: At 7 days, there was no significant difference in the severity of inflammation between the control group, white MTA, and white Portland cement groups. In the 14 day, 21 day and 30 day test periods, control group had significantly less inflammation than white MTA and white Portland cement. There was no significant difference in the grading of inflammation between white MTA and white Portland cement. All materials exhibited thick capsule at 7 days and thin capsule by 30 days. Conclusion: Both white MTA and white Portland cement were not completely non-irritating at the end of 30 days as evidenced by the presence of mild inflammation. However, the presence of a thin capsule around the materials, similar to the control group, indicates good tissue tolerance. White MTA and white Portland cement seem to be materials of comparable biocompatibility.

  9. Bioactive coatings on Portland cement substrates: Surface precipitation of apatite-like crystals

    Energy Technology Data Exchange (ETDEWEB)

    Gallego, Daniel [Biomedical Engineering Department, Ohio State University, 1080 Carmack Road, 270 Bevis Hall, Columbus (OH) - 43210 (United States); Higuita, Natalia [Biomedical Engineering Department, Ohio State University, 1080 Carmack Road, 270 Bevis Hall, Columbus (OH) - 43210 (United States); Grupo de Investigacion en Ingenieria Biomedica CES-EIA (GIBEC), Carrera 43 A No. 52 Sur - 99, Sabaneta (Colombia); Garcia, Felipe [Grupo de Investigacion en Ingenieria Biomedica CES-EIA (GIBEC), Carrera 43 A No. 52 Sur - 99, Sabaneta (Colombia); Ferrell, Nicholas [Biomedical Engineering Department, Ohio State University, 1080 Carmack Road, 270 Bevis Hall, Columbus (OH) - 43210 (United States); Hansford, Derek J. [Biomedical Engineering Department, Ohio State University, 1080 Carmack Road, 270 Bevis Hall, Columbus (OH) - 43210 (United States)], E-mail: hansford.4@osu.edu

    2008-04-01

    We report a method for depositing bioactive coatings onto cement materials for bone tissue engineering applications. White Portland cement substrates were hydrated under a 20% CO{sub 2} atmosphere, allowing the formation of CaCO{sub 3}. The substrates were incubated in a calcium phosphate solution for 1, 3, and 6 days (CPI, CPII, and CPIII respectively) at 37 deg. C to induce the formation of carbonated apatite. Cement controls were prepared and hydrated with and without CO{sub 2} atmosphere (C+ and C- respectively). The presence of apatite-like crystals was verified by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The substrate cytocompatibility was evaluated via SEM after 24 hour cell cultures. SEM revealed the presence Ca(OH){sub 2} on C-, and CaCO{sub 3} on C+. Apatite-like crystals were detected only on CPIII, confirmed by phosphorus EDS peaks only for CPIII. Cells attached and proliferated similarly well on all the substrates except C-. These results prove the feasibility of obtaining biocompatible and bioactive coatings on Portland cement for bone tissue engineering applications.

  10. Use of coir pith particles in composites with Portland cement.

    Science.gov (United States)

    Brasileiro, Gisela Azevedo Menezes; Vieira, Jhonatas Augusto Rocha; Barreto, Ledjane Silva

    2013-12-15

    Brazil is the fourth largest world's producer of coconut (Cocos nucifera L.). Coconut crops generate several wastes, including, coir pith. Coir pith and short fibers are the byproducts of extracting the long fibers and account for approximately 70% of the mature coconut husk. The main use of coir pith is as an agricultural substrate. Due to its shape and small size (0.075-1.2 mm), this material can be considered as a particulate material. The aim of this study was to evaluate the use of coir pith as an aggregate in cementitious composites and to evaluate the effect of the presence of sand in the performance of these composites. Some composites were produced exclusively with coir pith particles and other composites with coir pith partially substituting the natural sand. The cementitious composites developed were tested for their physical and mechanical properties and characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy to evaluate the effect of coir pith particles addition in cement paste and sand-cement-mortar. The statistical significance of the results was evaluated by one-way analysis of variance (ANOVA) test followed by multiple comparisons of the means by Tukey's test that showed that the composites with coir pith particles, with or without natural sand, had similar mechanical results, i.e., means were not statistically different at 5% significance level. There was a reduction in bulk density and an improved post-cracking behavior in the composites with coir pith particles compared to conventional mortar and to cement paste. These composites can be used for the production of lightweight, nonstructural building materials, according to the values of compressive strength (3.97-4.35 MPa) and low bulk density (0.99-1.26 g/cm(3)).

  11. Effect of saliva and blood contamination on the bi-axial flexural strength and setting time of two calcium-silicate based cements: Portland cement and biodentine.

    Science.gov (United States)

    Alhodiry, W; Lyons, M F; Chadwick, R G

    2014-03-01

    This study evaluated the effect of contamination with saliva and blood on the bi-axial flexural strength and setting time of pure gray Portland cement and Biodentine (Septodont, Allington, UK). A one-way ANOVA showed that contamination caused no significant difference between the cements in bi-axial flexural strength (P> 0.05). However there was a significant difference in setting time (Pcement taking longer than Biodentine, regardless of the contaminant, and contamination with blood increased the setting time of both materials. Biodentine was similar in strength to Portland cement, but had a shorter setting time for both contaminated and non-contaminated samples.

  12. Effects of composition and exposure on the solar reflectance of Portland cement concrete

    Energy Technology Data Exchange (ETDEWEB)

    Levinson, Ronnen; Akbari, Hashem

    2001-12-21

    Increasing the solar reflectance (albedo) of a paved surface keeps it cooler in the sun, reducing convection of heat from pavement to air and thereby decreasing the ambient air temperature. Simulations of the influence of pavement albedo on air temperature in Los Angeles predict that increasing the albedo of 1,250 km2 of pavement by 0.25 would save cooling energy worth $15M yr-1, and reduce smog-related medical and lost-work expenses by $76M yr-1. Most sidewalks and a small fraction of roads and parking areas are paved with portland cement concrete, which can be made quite reflective through suitable choice of cement and aggregate. Variations with composition and environmental exposure of the albedos of portland cement concrete pavements were investigated through laboratory fabrication and exposure of 32 mixes of concrete. Twenty-four mixes yielded substandard, ''rough'' concretes due to high, unmet aggregate water demand. The albedos of the remaining eight ''smooth'' concrete mixes ranged from 0.41 to 0.77 (mean 0.59). Simulated weathering, soiling, and abrasion each reduced average concrete albedo (mean decreases 0.06, 0.05, and 0.19, respectively), though some samples became slightly more reflective through weathering or soiling. Simulated rain (wetting) strongly depressed the albedos of concretes (mean decrease 0.23) until their surfaces were dried. Concrete albedo grew as the cement hydration reaction progressed (mean increase 0.08), but stabilized within six weeks of casting. White-cement concretes were on average significantly more reflective than gray-cement concretes. The albedo of the most-reflective white-cement concrete was 0.18 to 0.39 higher than that of the most-reflective gray-cement concrete, depending on state of exposure. Concrete albedo generally correlated with cement albedo and sand albedo, and, after abrasion, with rock albedo. Cement albedo had a disproportionately strong influence on the reflectance

  13. Glycerol Salicylate-based Pulp-Capping Material Containing Portland Cement.

    Science.gov (United States)

    Portella, Fernando Freitas; Collares, Fabrício Mezzomo; Santos, Paula Dapper; Sartori, Cláudia; Wegner, Everton; Leitune, Vicente Castelo Branco; Samuel, Susana Maria Werner

    2015-01-01

    The purpose of this study was to evaluate the water sorption, solubility, pH and ability to diffuse into dentin of a glycerol salicylate-based, pulp-capping cement in comparison to a conventional calcium hydroxide-based pulp capping material (Hydcal). An experimental cement was developed containing 60% glycerol salicylate resin, 10% methyl salicylate, 25% calcium hydroxide and 5% Portland cement. Water sorption and solubility were determined based on mass changes in the samples before and after the immersion in distilled water for 7 days. Material discs were stored in distilled water for 24 h, 7 days and 28 days, and a digital pHmeter was used to measure the pH of water. The cement's ability to diffuse into bovine dentin was assessed by Raman spectroscopy. The glycerol salicylate-based cement presented higher water sorption and lower solubility than Hydcal. The pH of water used to store the samples increased for both cements, reaching 12.59 ± 0.06 and 12.54 ± 0.05 after 7 days, for Hydcal and glycerol salicylate-based cements, respectively. Both cements were able to turn alkaline the medium at 24 h and sustain its alkalinity after 28 days. Hydcal exhibited an intense diffusion into dentin up to 40 µm deep, and the glycerol salicylate-based cement penetrated 20 µm. The experimental glycerol salicylate-based cement presents good sorption, solubility, ability to alkalize the surrounding tissues and diffusion into dentin to be used as pulp capping material.

  14. Vibrational study on the bioactivity of Portland cement-based materials for endodontic use

    Science.gov (United States)

    Taddei, P.; Tinti, A.; Gandolfi, M. G.; Rossi, P. L.; Prati, C.

    2009-04-01

    The bioactivity of a modified Portland cement (wTC) and a phosphate-doped wTC cement (wTC-P) was studied at 37 °C in Dulbecco's Phosphate Buffered Saline (DPBS). The cements, prepared as disks, were analysed at different ageing times (from 1 day to 2 months) by micro-Raman and ATR/FT-IR spectroscopies. The presence of deposits on the surface of the cements and the composition changes as a function of the storage time were investigated. The presence of an apatite deposit on the surface of both cements was already revealed after one day of ageing in DPBS. The trend of the I 965/I 991 Raman intensity ratio indicated the formation of a meanly thicker apatite deposit on the wTC-P cement at all the investigated times. This result was confirmed by the trend of the I 1030/I 945 IR intensity ratio calculated until 14 days of ageing. At 2 months, the thickness of the apatite deposit on wTC and wTC-P was about 200 and 500 μm, respectively, as estimated by micro-Raman spectroscopy, confirming the higher bioactivity of the phosphate-doped cement. Vibrational techniques allowed to gain more insights into the cement transformation and the different hydration rates of the various cement component. The setting of the cement and the formation of the hydrated silicate gel (C-S-H phase) was spectroscopically monitored through the I 830/I 945 IR intensity ratio.

  15. Mechanical Properties and Microstructure of Portland Cement Concrete Prepared with Coral Reef Sand

    Institute of Scientific and Technical Information of China (English)

    WANG Qiankun; LI Peng; TIAN Yapo; CHEN Wei; SU Chunyi

    2016-01-01

    The feasibility of using coral reef sand (CRS) in Portland cement concrete is investigated by testing the mechanical property and microstructure of concrete. The composition, structure and properties of the CRS are analyzed. Mechanical properties and microstructure of concrete with CRS are studied and compared to concrete with natural river sand. The relationship between the microstructure and performance of CRS concrete is established. The CRS has a porous surface with high water intake capacity, which contributes to the mechanical properties of concrete. The interfacial transition zone between the cement paste and CRS is densiifed compared to normal concrete with river sand. Hydration products form in the pore space of CRS and interlock with the matrix of cement paste, which increases the strength. The total porosity of concrete prepared with CRS is higher than that with natural sand. The main difference in pore size distribution is the fraction of ifne pores in the range of 100 nm.

  16. Lime kiln dust as a potential raw material in portland cement manufacturing

    Science.gov (United States)

    Miller, M. Michael; Callaghan, Robert M.

    2004-01-01

    In the United States, the manufacture of portland cement involves burning in a rotary kiln a finely ground proportional mix of raw materials. The raw material mix provides the required chemical combination of calcium, silicon, aluminum, iron, and small amounts of other ingredients. The majority of calcium is supplied in the form of calcium carbonate usually from limestone. Other sources including waste materials or byproducts from other industries can be used to supply calcium (or lime, CaO), provided they have sufficiently high CaO content, have low magnesia content (less than 5 percent), and are competitive with limestone in terms of cost and adequacy of supply. In the United States, the lime industry produces large amounts of lime kiln dust (LKD), which is collected by dust control systems. This LKD may be a supplemental source of calcium for cement plants, if the lime and cement plants are located near enough to each other to make the arrangement economical.

  17. Performance of portland limestone cements: Cements designed to be more sustainable that include up to 15% limestone addition

    Science.gov (United States)

    Barrett, Timothy J.

    In 2009, ASTM and AASHTO permitted the use of up to 5% interground limestone in ordinary portland cement (OPC) as a part of a change to ASTM C150/AASHTO M85. When this work was initiated a new proposal was being discussed that would enable up to 15% interground limestone cement to be considered in ASTM C595/AASHTO M234. This work served to provide rapid feedback to the state department of transportation and concrete industry for use in discussions regarding these specifications. Since the time this work was initiated, ASTM C595/AASHTO M234 was passed (2012c) and PLCs are now able to be specified, however they are still not widely used. The proposal for increasing the volume of limestone that would be permitted to be interground in cement is designed to enable more sustainable construction, which may significantly reduce the CO2 that is embodied in the built infrastructure while also extending the life of cement quarries. Research regarding the performance of cements with interground limestone has been conducted by the cement industry since these cements became widely used in Europe over three decades ago, however this work focuses on North American Portland Limestone Cements (PLCs) which are specifically designed to achieve similar performance as the OPCs they replace.This thesis presents a two-phase study in which the potential for application of cements containing limestone was assessed. The first phase of this study utilized a fundamental approach to determine whether cement with up to 15% of interground or blended limestone can be used as a direct substitute to ordinary portland cement. The second phase of the study assessed the concern of early age shrinkage and cracking potential when using PLCs, as these cements are typically ground finer than their OPC counterparts. For the first phase of the study, three commercially produced PLCs were obtained and compared to three commercially produced OPCs made from the same clinker. An additional cement was tested

  18. Properties of Portland cement concretes containing pozzolanic admixtures

    Science.gov (United States)

    Simmons, D. D.; Pasko, T. J., Jr.; Jones, W. R.

    1981-04-01

    A laboratory comparison was made of the properties of a concrete containing no pozzolan with several mixtures containing pozzolans. Used were a natural pozzolan (Lassenite), two fly ashes of different fineness and low carbon and an amorphous silica fume dust from a metal-producing plant. One cement, one coarse crushed limestone aggregate, and one fine river aggregate were used. Replacing a faster reacting binder with a slower one, produced lower early strengths and adversely affected the properties which are highly dependent on strength. The measures of durability were greatly affected by the air contents and aging or treatment prior to exposure. The amorphous silica fume dust increased the early strengths of a fly ash mixture.

  19. Prospection of Portland cement raw material: A case study in the Marmara region of Turkey

    Science.gov (United States)

    Özgüner, A. M.

    2014-09-01

    Representative sampling of the raw materials used to make Portland cement, correct calculations for the possible clinker mixtures, sufficient reserves of the raw materials and selection of the correct infrastructure for the location of a cement factory are essential to the protection of the great investment in the factory. The results of chemical analyses of pipe samples taken in the field at right angles to the strikes of favourable limestone, clay, shale, and marl outcrops were used in Kind's lime saturation formula for clinker calculations of the possible mixtures. The cement modulus values were calculated using the corresponding clinker oxide ratios and were confirmed to be within the standard intervals for positive cement raw material mixtures. The most promising raw material source, a double lithologic mixture of limestone and mudstone was found during the prospection in north of Bilecik Province, where rhyolitic tuff outcrops with pozzolanic properties also exist. Some marble quarries nearby have been inclined to dispose of their marble wastes for use in cement production to prevent polluting the environment with them. The nearby Gemlik fertiliser factory provides inexpensive waste gypsum that can be used as a cool cement mixing material. The limestone, mudstone and trass raw material reserves in this area were calculated to be sufficient for the factory's requirements for more than 100 years of operation as results of the detailed geological mapping. The regional infrastructure is most suitable for distribution and marketing of cement products. The cement factory described in this study has been producing cement for the last 3 years, after coring and testing of the raw material reserves.

  20. Metakaolin sand – a promising addition for Portland cement

    Directory of Open Access Journals (Sweden)

    Janotka, I.

    2010-06-01

    Full Text Available The kaolin sand resource at the Vyšný Petrovec quarry in Slovakia comes to a total of 20 megatonnes. The metakaolin material obtained by heating kaolin sand at 650 ºC contains from 31.5 to 40% (wt metakaolinite, as well as illite, muscovite, quartz and feldspar. The aim of this study was to verify whether this calcined sand (MK1 is a pozzolanic material and characterize the cements and mortars prepared with it. The hydration reactions taking place in the blends were assessed with conduction calorimetry, X-ray diffraction (XRD and differential thermal analysis-thermogravimetry (DTA-TG. Blend and mortar strength development and pore structure were also evaluated. The results obtained showed that this metakaolin sand (MK-1 is a pozzolanic material apt for use as a cement addition and for making mortars.

    Las reservas de arena caolínica de la cantera eslovaca de Vyšný Petrovec ascienden a un total de 20 millones de toneladas. El material metacaolínico, que resulta al calentar la arena caolínica a 650 ºC, contiene entre un 31,5 y un 40% de metacaolinita, además de ilita, moscovita, cuarzo y feldespato. El objetivo de este estudio ha sido comprobar que esa arena calcinada es un material puzolánico; así como caracterizar los cementos y morteros preparados con dicha arena (MK-1. La hidratación de las mezclas se evaluó mediante calorimetría de conducción, y difracción de rayos X (DRX y Análisis térmico-diferencial y termogravimétrico (ATD-TG. Se ha evaluado el desarrollo resistente de las mezclas y morteros; así como su estructura porosa. Los resultados obtenidos han demostrado que esa arena metacolínica (MK-1 es un material puzolánico y que podría utilizarse como adición al cemento y en la preparación de morteros.

  1. The impact of zirconium oxide radiopacifier on the early hydration behaviour of white Portland cement.

    Science.gov (United States)

    Coleman, Nichola J; Li, Qiu

    2013-01-01

    Zirconium oxide has been identified as a candidate radiopacifying agent for use in Portland cement-based biomaterials. During this study, the impact of 20 wt.% zirconium oxide on the hydration and setting reactions of white Portland cement (WPC) was monitored by powder X-ray diffraction (XRD), (29)Si and (27)Al magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), transmission electron microscopy (TEM) and Vicat apparatus. The presence of 20 wt.% zirconium oxide particles in the size-range of 0.2 to 5 μm was found to reduce the initial and final setting times of WPC from 172 to 147 min and 213 to 191 min, respectively. Zirconium oxide did not formally participate in the chemical reactions of the hydrating cement; however, the surface of the zirconium oxide particles presented heterogeneous nucleation sites for the precipitation and growth of the early C-S-H gel products which accelerated the initial setting reactions. The presence of zirconium oxide was found to have little impact on the development of the calcium (sulpho)aluminate hydrate phases.

  2. The Estimation of Compaction Parameter Values Based on Soil Properties Values Stabilized with Portland Cement

    Science.gov (United States)

    Lubis, A. S.; Muis, Z. A.; Pasaribu, M. I.

    2017-03-01

    The strength and durability of pavement construction is highly dependent on the properties and subgrade bearing capacity. This then led to the idea of the selection methods to estimate the density of the soil with the proper implementation of the system, fast and economical. This study aims to estimate the compaction parameter value namely the maximum dry unit weight (γd max) and optimum moisture content (wopt) of the soil properties value that stabilized with Portland Cement. Tests conducted in the laboratory of soil mechanics to determine the index properties (fines and liquid limit) and Standard Compaction Test. Soil samples that have Plasticity Index (PI) between 0-15% then mixed with Portland Cement (PC) with variations of 2%, 4%, 6%, 8% and 10%, each 10 samples. The results showed that the maximum dry unit weight (γd max) and wopt has a significant relationship with percent fines, liquid limit and the percentation of cement. Equation for the estimated maximum dry unit weight (γd max) = 1.782 - 0.011*LL + 0,000*F + 0.006*PS with R2 = 0.915 and the estimated optimum moisture content (wopt) = 3.441 + 0.594*LL + 0,025*F + 0,024*PS with R2 = 0.726.

  3. Carbonatation Influence on Fly Ash and Portland Cement Mortars

    Directory of Open Access Journals (Sweden)

    P.L. Valdez–Tamez

    2009-01-01

    Full Text Available The influence of carbonation on mortars containing 25% of fly ash instead of the cementitious materials was studied. Mortar cylinder specimens were fabricated for 4 different W/C ratios: 0.35, 0.45, 0.55 and 0.65. Mortars with and without fly ash were subjected to an accelerated carbonation process. Volumetric weight, water absorption, compressive strength, water permeability, pH and mercury intrusion porosimetry of the mortar specimens were determined. Due to the fly ash pozzolanic potential, for all W/C ratios, results of the compressive strength tests at 28 days of the mortars with and without fly ash were similar. Mortars with fly ash presented similar water permeability as mortars without fly ash. PH results showed that alkalinity reduction is lower in mortars with fly ash compared to those containing cement only. In all the mortars, the porosimetric analysis indicated that porosity is reduced due to carbonation. Further more, it is showed the predominance of the macro and mesopores.

  4. WOOD PRE-TREATMENT INFLUENCE ON THE HYDRATION OF PORTLAND CEMENT IN COMBINATION WITH SOME TROPICAL WOOD SPECIES

    Directory of Open Access Journals (Sweden)

    Nusirat Aderinsola SADIKU

    2014-06-01

    Full Text Available The influence of three pre-treatment methods on the hydration characteristics of Portland cement in combination with three tropical hardwood species was investigated. The maximum hydration temperature and time to reach maximum hydration temperature were analysed for the wood-cement-water mixtures of the three species after removing inhibitory extractives of wood samples by extraction with 5% Sodium hydroxide (NaOH, cold and hot water after removing inhibitory extractives of wood samples. There were differences in the hydration reaction of the wood species with Portland cement using the different pre-treatment methods. The compatibility of the wood species with Portland cement improved following pre-treatment. Sodium hydroxide pre-treatment had the most significant effect followed by hot water. Terminalia ivorensis (Idigbo, and Antiaris africana (Oriro species showed considerable improvement in their compatibility with Portland cement at 5% Sodium hydroxide pre-treatment with maximum hydration temperature of 65oC where Arere had 60.5oC where both cold and hot water were unable to raise the hydration temperature beyond 55.5oC . This study shows that the wood species requires more than cold and hot water extraction to make them suitable for wood cement composite materials as extraction with sodium hydroxide (1% solution was found to be the most effective treatment for the wood species under investigation.

  5. Dimensional stability of materials based on Portland cement at the early stages

    Science.gov (United States)

    Mesa Yandy, Angélica; Zerbino, Raúl L.; Giaccio, Graciela M.; Russo, Nélida A.; Duchowicz, Ricardo

    2014-09-01

    In this work two fiber optic sensing techniques are used to study the dimensional stability in fresh state of different cementitious materials. A conventional Portland cement mortar and two commercial grouts were selected. The measurements were performed by using a Bragg grating embedded in the material and a non-contact Fizeau interferometer. The first technique was applied in a horizontal sample scheme, and the second one, by using a vertical configuration. In addition, a mechanical length comparator was used in the first case in order to compare the results. The evolution with time of the dimensional changes of the samples and the analysis of the observed behavior are included.

  6. Solidification/Stabilization of Fly Ash from a Municipal Solid Waste Incineration Facility Using Portland Cement

    Directory of Open Access Journals (Sweden)

    Qiang Tang

    2016-01-01

    Full Text Available This study investigated the solidification/stabilization of fly ash containing heavy metals using the Portland cement as a binder. It is found that both the cement/fly ash ratio and curing time have significant effects on the mechanical (i.e., compressive strength and leaching behaviors of the stabilized fly ash mixtures. When the cement/fly ash ratio increases from 4 : 6 to 8 : 2, the increase of compressive strength ratio raises from 42.24% to 80.36%; meanwhile, the leaching amount of heavy metals decreases by 2.33% to 85.23%. When the curing time increases from 3 days to 56 days, the compressive strength ratio of mixtures raises from 240.00% to 414.29%; meanwhile, the leaching amount of heavy metals decreases by 16.49% to 88.70%. The decrease of compressive strength with the lower cement/fly ash ratios and less curing time can be attributed to the increase of fly ash loading, which hinders the formation of ettringite and destroys the structure of hydration products, thereby resulting in the pozzolanic reaction and fixation of water molecules. Furthermore, the presence of cement causes the decrease of leaching, which results from the formation of ettringite and the restriction of heavy metal ion migration in many forms, such as C-S-H gel and adsorption.

  7. Constitutive modeling of the aging viscoelastic properties of portland cement paste

    Science.gov (United States)

    Grasley, Zachary C.; Lange, David A.

    2007-12-01

    Analytical approaches for modeling aging viscoelastic behavior of concrete include the time-shift approach (analogous to time-temperature superposition), the solidification theory, and the dissolution-precipitation approach. The aging viscoelastic properties of concrete are generally attributed solely to the cement paste phase since the aggregates are typically linear elastic. In this study, the aging viscoelastic behavior of four different cement pastes has been measured and modeled according to both the time-shift approach and the solidification theory. The inability of each individual model to fully characterize the aging viscoelastic response of the materials provides insight into the mechanisms for aging of the viscoelastic properties of cement paste and concrete. A model that considers aging due to solidification in combination with inherent aging of the cement paste gel (modeled using the time-shift approach) more accurately predicted the aging viscoelastic behavior of portland cement paste than either the solidification or time-shift approaches independently. The results provide evidence that solidification and other intrinsic gel aging mechanisms are concurrently active in the aging process of cementitious materials.

  8. Effects of occupational dust exposure on the health status of portland cement factory workers

    Directory of Open Access Journals (Sweden)

    R Manjula

    2013-07-01

    Full Text Available Introduction: Chronic exposure to Portland cement dust has been reported to lead to greater prevalence of various clinical conditions (includes both respiratory and non-respiratory. These conditions are consistently associated with the degree and duration of exposure. Regular use of appropriate personal protective equipment if made available at the work site could protect the cement factory workers from adverse health effects. Objective: To study the morbidity profile of the cement factory workers. Type of Study: Retrospective cohort study. Material and Methods: This study was conducted in the Portland Cement Factory in North Karnataka. Data was collected using predesigned questionnaire by personal interview method and clinical examination. A total of 64 male workers are randomly selected who are working in various departments like crushing, raw/cement mill, rotary kiln and packing department. Equal number of unexposed controls was selected from the area atleast 5 kms from the factory and those who are not exposed to cement dust in the past, who are matched for age, Socio economic status and smoking with the exposed population. Statistical Analysis: Chisquare test for qualitative data and unpaired t test for quantitative data using Epi info. Results: A total of 64 male workers and equal number of matched controls who are not exposed to the cement dust were included in the study. Among exposed maximum of 36% were employed in Crushing department, 25% each in Packing and cement/raw mill. Systolic and Diastolic blood pressure was found to be higher among the exposed, which is statistically highly significant (p<0.001. There is significant increase in weight among exposed (p<0.001. Maximum 29(45.3% of the workers had stuffy nose and epistaxis when compared to unexposed with Relative risk(RR of 2.6, followed by Dermatological complaints and lower respiratory complaints with RR of 2.18 and 2.3 respectively. Conclusion: Personal protective equipment

  9. Water dynamics in hardened ordinary Portland cement paste or concrete: from quasielastic neutron scattering.

    Science.gov (United States)

    Bordallo, Heloisa N; Aldridge, Laurence P; Desmedt, Arnaud

    2006-09-14

    Portland cement reacts with water to form an amorphous paste through a chemical reaction called hydration. In concrete the formation of pastes causes the mix to harden and gain strength to form a rock-like mass. Within this process lies the key to a remarkable peculiarity of concrete: it is plastic and soft when newly mixed, strong and durable when hardened. These qualities explain why one material, concrete, can build skyscrapers, bridges, sidewalks and superhighways, houses, and dams. The character of the concrete is determined by the quality of the paste. Creep and shrinkage of concrete specimens occur during the loss and gain of water from cement paste. To better understand the role of water in mature concrete, a series of quasielastic neutron scattering (QENS) experiments were carried out on cement pastes with water/cement ratio varying between 0.32 and 0.6. The samples were cured for about 28 days in sealed containers so that the initial water content would not change. These experiments were carried out with an actual sample of Portland cement rather than with the components of cement studied by other workers. The QENS spectra differentiated between three different water interactions: water that was chemically bound into the cement paste, the physically bound or "glassy water" that interacted with the surface of the gel pores in the paste, and unbound water molecules that are confined within the larger capillary pores of cement paste. The dynamics of the "glassy" and "unboud" water in an extended time scale, from a hundred picoseconds to a few nanoseconds, could be clearly differentiated from the data. While the observed motions on the picosecond time scale are mainly stochastic reorientations of the water molecules, the dynamics observed on the nanosecond range can be attributed to long-range diffusion. Diffusive motion was characterized by diffusion constants in the range of (0.6-2) 10(-9) m(2)/s, with significant reduction compared to the rate of diffusion

  10. Pore size distribution, strength, and microstructure of portland cement paste containing metal hydroxide waste

    Energy Technology Data Exchange (ETDEWEB)

    Majid, Z.A.; Mahmud, H.; Shaaban, M.G.

    1996-12-31

    Stabilization/solidification of hazardous wastes is used to convert hazardous metal hydroxide waste sludge into a solid mass with better handling properties. This study investigated the pore size development of ordinary portland cement pastes containing metal hydroxide waste sludge and rice husk ash using mercury intrusion porosimetry. The effects of acre and the addition of rice husk ash on pore size development and strength were studied. It was found that the pore structures of mixes changed significantly with curing acre. The pore size shifted from 1,204 to 324 {angstrom} for 3-day old cement paste, and from 956 to 263 {angstrom} for a 7-day old sample. A reduction in pore size distribution for different curing ages was also observed in the other mixtures. From this limited study, no conclusion could be made as to any correlation between strength development and porosity. 10 refs., 6 figs., 3 tabs.

  11. Increasing the compressive strength of portland cement concrete using flat glass powder

    Energy Technology Data Exchange (ETDEWEB)

    Miranda Junior, Edson Jansen Pedrosa de; Bezerra, Helton de Jesus Costa Leite; Politi, Flavio Salgado; Paiva, Antonio Ernandes Macedo, E-mail: edson.jansen@ifma.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia do Maranha (IFMA), Sao Luis, MA (Brazil). Dept. de Mecanica e Materiais

    2014-08-15

    This paper analyzes the compressive strength of Portland cement concrete in response to the incorporation of 5%, 10% and 20% of flat glass powder in place of sand, at w/c (water/cement) ratios of 0.50, 0.55 and 0.58. A statistical analysis of variance (ANOVA) was performed after 7, 14 and 28 days of curing. The compressive strength test results indicate that the concrete containing a w/c ratio of 0.50 can be used for structural applications, regardless of the waste glass content, as can that with a w/c ratio of 0.55 containing 20% of waste glass. We suggest that the use of flat glass powder in place of sand in the above mentioned percentages is feasible for the production of an environmentally appropriate and structurally applicable concrete. However, the concrete's fluidity and void content must be taken into account. (author)

  12. Dielectric properties of portland cement paste as a function of time since mixing

    Science.gov (United States)

    Camp, Paul R.; Bilotta, Stephen

    1989-12-01

    The dielectric properties of portland cement paste and mortar have been measured in the frequency range 100 Hz-7 MHz as a function of time since mixing. Over much of the spectrum, the ac conductance of the samples appears directly related to the amount of unbound water remaining in the sample and ionic conduction predominates. In addition, interesting structure was found in both the conductance and capacitance data at high frequencies as the free water content was reduced. We conclude that relatively simple measurements of this kind can be a useful tool in concrete research and may provide the basis for simple, in situ, nondestructive measurement of the degree of curing of concrete or for monitoring water migration in concrete structures. Measurements on sealed samples of partially or fully cured concrete reveal also the water-cement ratio of the original mix.

  13. Microstructure Development and Transport Properties of Portland Cement-fly Ash Binary Systems: in view of service life predictions

    OpenAIRE

    Z. Yu

    2015-01-01

    Fly ash is a by-product of burning coal in electric power generating plants. It is commonly known that owing to its pozzolanic properties fly ash is widely used as a partial replacement for Portland cement in concrete. The use of fly ash in concrete not only reduces the landfill costs of fly ash, but also reduces the use of Portland cement in concrete, consequently reduces CO2 emission per ton concrete. More important, the presence of fly ash improves the durability of concrete and extends th...

  14. The Greenhouse Gas Emission from Portland Cement Concrete Pavement Construction in China.

    Science.gov (United States)

    Ma, Feng; Sha, Aimin; Yang, Panpan; Huang, Yue

    2016-06-24

    This study proposes an inventory analysis method to evaluate the greenhouse gas (GHG) emissions from Portland cement concrete pavement construction, based on a case project in the west of China. The concrete pavement construction process was divided into three phases, namely raw material production, concrete manufacture and pavement onsite construction. The GHG emissions of the three phases are analyzed by a life cycle inventory method. The CO₂e is used to indicate the GHG emissions. The results show that for 1 km Portland cement concrete pavement construction, the total CO₂e is 8215.31 tons. Based on the evaluation results, the CO₂e of the raw material production phase is 7617.27 tons, accounting for 92.7% of the total GHG emissions; the CO₂e of the concrete manufacture phase is 598,033.10 kg, accounting for 7.2% of the total GHG emissions. Lastly, the CO₂e of the pavement onsite construction phase is 8396.59 kg, accounting for only 0.1% of the total GHG emissions. The main greenhouse gas is CO₂ in each phase, which accounts for more than 98% of total emissions. N₂O and CH₄ emissions are relatively insignificant.

  15. Use of disposed waste ash from landfills to replace Portland cement.

    Science.gov (United States)

    Rukzon, Sumrerng; Chindaprasirt, Prinya

    2009-09-01

    In this study, waste ash was utilized as a pozzolanic material in blended Portland cement in order to reduce negative environmental effects and landfill volume required to dispose of waste ash. The influence of waste ash, namely palm oil fuel ash, rice husk ash and fly ash on compressive strength and sulfate resistance in mortar were studied and evaluated by some accelerated short-term techniques in sodium sulfate solutions. Ordinary Portland cement (OPC) was partially replaced with ground palm oil fuel ash (POA), ground rice husk ash (RHA) and classified fly ash (FA). Single pozzolan and a blend of equal weight portions of POA, RHA and FA were also used. The resistance to sulfate attack of mortar improves substantially with partial replacement of OPC with POA, RHA and FA. The use of a blend of equal weight portions of FA and POA or RHA produced mixes with good strength and resistance to sulfate attack. POA, RHA and FA have a high potential to be used as a pozzolanic material.

  16. Exposure to cement dust at a Portland cement factory and the risk of cancer.

    Science.gov (United States)

    Vestbo, J; Knudsen, K M; Raffn, E; Korsgaard, B; Rasmussen, F V

    1991-01-01

    The relation between exposure to cement dust and cancer was examined in a population of 546 cement workers and a reference population of 858 randomly sampled men of similar age and area of residence. In 1974 all men gave lifelong occupational and smoking histories; information on incidence of cancer in the period 1974-85 was obtained from the Danish Cancer Registry. No increased risk of overall cancer was found among cement workers. Among men with more than 20 years exposure to cement dust, 14 cases of respiratory cancer were observed (observed/expected (O/E) 1.52, 95% confidence interval (95% CI) 0.90-2.57) when compared with all Danish men. Men with 1-20 years exposure had O/E 1.14 (95% CI 0.59-2.19) based on nine cases of cancer. After excluding all men with documented exposure to asbestos during employment in an asbestos cement factory no increased risk of overall cancer or respiratory cancer was found among cement workers compared with white collar workers from the local reference population, using a Cox regression model controlling for age and smoking habits. Relative risks were 0.5 (95% CI 0.1-1.5) and 1.0 (95% CI 0.4-2.6) for men with 1-20 and more than 20 years of exposure to cement dust respectively compared with white collar workers. PMID:1772795

  17. Analysis of Metal Contents in Portland Type V and MTA-Based Cements

    Directory of Open Access Journals (Sweden)

    Maura Cristiane Gonçales Orçati Dorileo

    2014-01-01

    Full Text Available The aim of this study was to determine, by Atomic Absorption Spectrometry (AAS, the concentration levels of 11 metals in Type V gray and structural white PC, ProRoot MTA, and MTA Bio. Samples, containing one gram of each tested cement, were prepared and transferred to a 100 mL Teflon tube with a mixture of 7.0 mL of nitric acid and 21 mL of hydrochloric acid. After the reaction, the mixture was filtered and then volumed to 50 mL of distilled water. For each metal, specific patterns were determined from universal standards. Arsenic quantification was performed by hydride generator. The analysis was performed five times and the data were statistically analyzed at 5% level of significance. Only the cadmium presented concentration levels of values lower than the quantification limit of the device. The AAS analysis showed increased levels of calcium, nickel, and zinc in structural white PC. Type V PC presented the greatest concentration levels of arsenic, chromium, copper, iron, lead, and manganese (P<0.05. Bismuth was found in all cements, and the lowest concentration levels were observed in Portland cements, while the highest were observed in ProRoot MTA. Both PC and MTA-based cements showed evidence of metals inclusion.

  18. Relation between the Rheology Characteristic and Initial Hydration Structure of Portland Cement

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on the rheology characteristic and the resistivity variation under alternating electric-field of Portland cement hydration by means of AR2000 advanced rheometer and non-contacting electrical resistivity device, the influence of cement kinds and the chemical admixtures on the initial rheology characteristic and structure forming and developing of cement hydration was studied. The relationship between the rheology characteristic, the initial hydration structure forming and the hydration process at very early ages was analyzed by macro properties and microstructure tests. The results showed that, the storage modulus, acted as S, could be described more subtle distinction accompanying with hydration of fresh paste model at very early period. Combining the resistivity alterations, a sudden change on structure forming emerged when the hydration of cement becoming inducing age. The rheology characteristic was interrelated to the hydration structure forming, development and the physical mechanics properties. The sudden change on storage modulus moved up due to the addition of retarder, but the structure forming and developing was retarded to a certain extent.

  19. Effect of fly ash on the optimum sulfate of Portland Cement

    Science.gov (United States)

    Niemuth, Mark D.

    Calcium sulfate is typically added to ordinary portland cement (OPC) clinker during grinding to prevent flash set and to improve early-age strength development without causing volume instabilities. Recent changes to ASTM C150, Standard Specification for Portland Cement, have enabled greater flexibility in determining optimum sulfate levels in portland cement by not requiring ASTM C563, Approximation of Optimum SO3 in Hydraulic Cement Using Compressive Strength, to be used in setting sulfate target levels. ASTM C563 requires strength testing using only the hydraulic cement, which is not always indicative of the optimum sulfate for field use, since supplementary materials (e.g., fly ash) may be used by the concrete producer. Adding additional sulfate to account for the sulfate demand of fly ashes can enable an improvement in the early age strength for cement-fly ash systems and decrease in problems that may be attributed to OPC-admixture-fly ash incompatibility such as abnormal setting and slow strength gain. This thesis provides experimental data on the strength development and heat release during early hydration for cement-fly ash systems with different sulfate levels. The thesis focused on high calcium fly ashes, but low calcium fly ash was also tested. It is demonstrated that some fly ashes have their own sulfate demand and when these ashes are used in cement-fly ash blends there is effectively an increase in the optimal sulfate level that could be used for the OPC. It is also shown that optimum sulfate determined by heat of hydration measured with isothermal calorimetry is similar to the optimum sulfate determined by compressive strength at 1 day. Using isothermal calorimetry can result in substantial time and cost savings at plants for determining the optimal sulfate content. Theories for the mechanisms that drive the differences in sulfate demand in OPC are reviewed. These theories are adapted for OPC-fly ash blends and are outlined, tested and discussed. The

  20. Solidification of ion exchange resins saturated with Na+ ions: Comparison of matrices based on Portland and blast furnace slag cement

    Science.gov (United States)

    Lafond, E.; Cau dit Coumes, C.; Gauffinet, S.; Chartier, D.; Stefan, L.; Le Bescop, P.

    2017-01-01

    This work is devoted to the conditioning of ion exchange resins used to decontaminate radioactive effluents. Calcium silicate cements may have a good potential to encapsulate spent resins. However, certain combinations of cement and resins produce a strong expansion of the final product, possibly leading to its full disintegration. The focus is placed on the understanding of the behaviour of cationic resins in the Na+ form in Portland or blast furnace slag (CEM III/C) cement pastes. During hydration of the Portland cement paste, the pore solution exhibits a decrease in its osmotic pressure, which causes a transient expansion of small magnitude of the resins. At 20 °C, this expansion takes place just after setting in a poorly consolidated material and is sufficient to induce cracks. In the CEM III/C paste, swelling of the resins also occurs, but before the end of setting, and induces limited stress in the matrix which is still plastic.

  1. Properties of SiMn slag as apozzolanic material in portland cement manufacture

    Directory of Open Access Journals (Sweden)

    Frías, M.

    2005-12-01

    Full Text Available The primary purpose of this study was to evaluate the behaviour of SiMn slag as a pozzolanic material in commercial Portland cement manufacture. This necessitated exploring different scientific and technical aspects to ensure a correct valuation. The results obtained revealed that silica and calcium are the main components of SiMn slag, whose pozzolanic activity occupies an intermediate position between silica fume and fly ash; it reduces heat of hydration and mortars made with cement containing SiMn slag exhibit compressive strength values similar to the figures for standard mortar. Consequently, the use of SiMn slag as an active addition to cement is feasible, inasmuch as the resulting product meets the requirements laid down in the present legislation.

    El objetivo principal de este trabajo es evaluar el comportamiento de la escoria de SiMn como material puzolánico en la fabricación de cementos Portland comerciales. Para ello, resulta necesario investigar diferentes aspectos científicos y técnicos que conlleven a una correcta valorización de las mismas. Los resultados obtenidos en el presente trabajo han puesto de manifiesto que la escoria de SiMn presenta una naturaleza sílico-cálcica, actividad puzolúnica intermedia entre el humo de sílice y ceniza volante, reduce el calor de hidratación y los morteros con escoria de SiMn muestra alcanzan resistencias a compresión similares a las del mortero patrón. Por lo tanto, la utilización de la escoria de SiMn como adición activa al cemento es viable, cumpliendo con las exigencias recogidas en la norma vigente.

  2. Microstructure Development and Transport Properties of Portland Cement-fly Ash Binary Systems: in view of service life predictions

    NARCIS (Netherlands)

    Yu, Z.

    2015-01-01

    Fly ash is a by-product of burning coal in electric power generating plants. It is commonly known that owing to its pozzolanic properties fly ash is widely used as a partial replacement for Portland cement in concrete. The use of fly ash in concrete not only reduces the landfill costs of fly ash, bu

  3. Comparing the Environmental Impacts of Alkali Activated Mortar and Traditional Portland Cement Mortar using Life Cycle Assessment

    Science.gov (United States)

    Matheu, P. S.; Ellis, K.; Varela, B.

    2015-11-01

    Since the year 1908 there has been research into the use alkali activated materials (AAM) in order to develop cementitious materials with similar properties to Ordinary Portland Cement. AAMs are considered green materials since their production and synthesis is not energy intensive. Even though AAMs have a high compressive strength, the average cost of production among other issues limits its feasibility. Previous research by the authors yielded a low cost AAM that uses mine tailings, wollastonite and ground granulated blast furnace slag (GGBFS). This mortar has an average compressive strength of 50MPa after 28 days of curing. In this paper the software SimaPro was used to create a product base cradle to gate Life Cycle Assessment (LCA). This compared the environmental impact of the AAM mortar to an Ordinary Portland Cement mortar (PCHM) with similar compressive strength. The main motivation for this research is the environmental impact of producing Ordinary Portland Cement as compared to alkali activated slag materials. The results of this LCA show that the Alkali Activated Material has a lower environmental impact than traditional Portland cement hydraulic mortar, in 10 out of 12 categories including Global Warming Potential, Ecotoxicity, and Smog. Areas of improvement and possible future work were also discovered with this analysis.

  4. Arsenic Encapsulation Using Portland Cement With Ferrous Sulfate/Lime And Terra-BondTM Technologies - Microcharacterization And Leaching Studies

    Science.gov (United States)

    This work reports the results of an investigation on the treatment and encapsulation of arsenic-containing materials by Portland cement with ferrous sulfate and lime (PFL) and Terra-BondTM, a commercially available patented technology. The arsenic materials treated we...

  5. Effect of Water to Cement Ratio and Age on Portland Composite Cement Mortar Porosity, Strength and Evaporation Rate

    Directory of Open Access Journals (Sweden)

    Enamur R. Latifee

    2016-08-01

    Full Text Available Durability and the compressive strength of concrete are directly related to the porosity. Water to cement ratio is the main parameter behind the nature and amount of pores within the matrix. Porosity is also influenced by the degree of cement hydration and the length of moist-curing. Even after the standard moist curing period, i.e. 28 days the concrete can gain strength and porosity can be reduced under ambient relative humidity and temperature. However, this fact, that is the age effect on porosity reduction of the cement mortar or concrete, kept in air with ambient relative humidity and temperature for long duration could not be found in the literature. Therefore, in this research, different w/c were used with constant amount Portland Composite Cement to find out whether the mortar porosity decreases significantly over time, after 28 days of water curing, while kept in air and if there is any interaction effect between the age of the mortar and different w/c; regarding porosity. It was also intended to find out if water-loss rate variation with different w/c has similar trend as porosity variation with different w/c. It was found that, there is significant decrease in porosity with time for the first six weeks in air and after that it dwindles down gradually, and there is no interaction between age and w/c. Also, after 100 days in air, samples were submerged under water for 24 hours and then kept in air for the evaporation in subsequent days. It has been found that the water evaporation vs. w/c curve, using 11-day evaporation of water from different w/c specimens in ambient condition is almost parallel to porosity vs. w/c curve. Therefore, 11-day evaporation of aged saturated mortar or concrete sample, such as core can also be used as a durability index, which can be used for old structure evaluation.

  6. Characterization via nuclear magnetic resonance of Portland cement and related materials

    Science.gov (United States)

    Edwards, Christopher Lane

    The physicochemical and engineering performance properties of several API class G and H ordinary Portland cements (OPCs) from various foreign and domestic sources have been investigated. The engineering performance properties are found to vary from sample to sample, and sources for this variation were sought out and identified. Magic angle spinning (MAS) 29Si nuclear magnetic resonance (NMR) experiments were marked by unusual relaxation behavior due to paramagnetism inherent in OPCs. A model system was created to mimic the paramagnetism of the cements and the system's relaxation behavior was analyzed. The iron in the calcium aluminoferrite (C4AF) provides the paramagnetism sufficient to substantially increase the relaxation rates of the 29Si in the tricalcium silicate (C3S) and dicalcium silicate (C2S) of cement. Several relaxation techniques were evaluated for analyzing cement relaxation, and saturation recovery was identified as the preferred technique. Correlations of data from the saturation recovery experiments with engineering performance properties, especially the strength development of cement pastes, were obtained facilely. An error analysis of the NMR and engineering performance testing techniques was conducted, which indicated that NMR measurements produced less error than the engineering performance tests. A best practice, modified from the saturation recovery experiment, is proposed for use in property correlations. Additionally, 13C MAS NMR was used to characterize various fluorinated single-walled carbon nanotubes (F-SWNTs), which proved surprisingly effective in attenuating 13C-19F dipolar interactions and quantifying the extent of functionalization present at high degrees of reaction. The mixed-metal nanocluster known as FeMoC was also characterized by MAS NMR. The impact of the paramagnetic Fe3+ in the Keplerate cage on the 31P nuclei in the caged Keggin ion of FeMoC was evident in the greatly reduced relaxation times measured.

  7. Evaluation of Compatibility between Beetle-Killed Lodgepole Pine (Pinus Contorta var. Latifolia Wood with Portland Cement

    Directory of Open Access Journals (Sweden)

    Ian D. Hartley

    2010-12-01

    Full Text Available The compatibility of wood from mountain pine beetle (Dendroctonus ponderosa killed lodgepole pine (Pinus contorta var. latifolia with Portland cement was investigated based on time-since-death as a quantitative estimator, and the presence of blue-stained sapwood, brown rot, or white rot as qualitative indicators. The exothermic behavior of cement hydration, maximum heat rate, time to reach this maximum, and total heat released within a 3.5–24 h interval were used for defining a new wood-cement compatibility index (CX. CX was developed and accounted for large discrepancies in assessing wood-cement compatibility compared to the previous methods. Using CX, no significant differences were found between fresh or beetle-killed wood with respect to the suitability for cement; except for the white rot samples which reached or exceeded the levels of incompatibility. An outstanding physicochemical behavior was also found for blue-stained sapwood and cement, producing significantly higher compatibility indices.

  8. Modeling of Hydration, Compressive Strength, and Carbonation of Portland-Limestone Cement (PLC Concrete

    Directory of Open Access Journals (Sweden)

    Xiao-Yong Wang

    2017-01-01

    Full Text Available Limestone is widely used in the construction industry to produce Portland limestone cement (PLC concrete. Systematic evaluations of hydration kinetics, compressive strength development, and carbonation resistance are crucial for the rational use of limestone. This study presents a hydration-based model for evaluating the influences of limestone on the strength and carbonation of concrete. First, the hydration model analyzes the dilution effect and the nucleation effect of limestone during the hydration of cement. The degree of cement hydration is calculated by considering concrete mixing proportions, binder properties, and curing conditions. Second, by using the gel–space ratio, the compressive strength of PLC concrete is evaluated. The interactions among water-to-binder ratio, limestone replacement ratio, and strength development are highlighted. Third, the carbonate material contents and porosity are calculated from the hydration model and are used as input parameters for the carbonation model. By considering concrete microstructures and environmental conditions, the carbon dioxide diffusivity and carbonation depth of PLC concrete are evaluated. The proposed model has been determined to be valid for concrete with various water-to-binder ratios, limestone contents, and curing periods.

  9. Degradation of Alumina and Magnesia Chrome refractory bricks in Portland cement kiln – Corrected version*

    Directory of Open Access Journals (Sweden)

    Ben Addi K.

    2014-05-01

    Full Text Available In cement plants, the refractory products are particularly confronted to partially liquid oxide phases at temperature ranging between 900°C and 1700°C. All constituents of these products have to resist not only to thermal constraints, but also to the thermochemical solicitations which result from contact material/coating. In order to study the phenomenon of degradation of refractory bricks in cement kilns and to identify the causes of their degradation, we proceed to the examination of industrial cases in cement kiln. Many chemical tests of the degraded refractory bricks have been done and the results acquired were compared to the ones not used. The analysis of the results is doing using different techniques (Loss of ignition, X-ray Fluorescence, X-ray Diffraction. The results show that the degradation of the used bricks in the clinkering and cooling zone is due to the infiltration of aggressive elements such us sulphur, alkali (Na2O, K2O .... The chemical interaction between the Portland clinker phases and refractory material has also an importance on the stability of the coating and consequently on the life of the refractories.

  10. Monitoring accelerated carbonation on standard Portland cement mortar by nonlinear resonance acoustic test

    Science.gov (United States)

    Eiras, J. N.; Kundu, T.; Popovics, J. S.; Monzó, J.; Borrachero, M. V.; Payá, J.

    2015-03-01

    Carbonation is an important deleterious process for concrete structures. Carbonation begins when carbon dioxide (CO2) present in the atmosphere reacts with portlandite producing calcium carbonate (CaCO3). In severe carbonation conditions, C-S-H gel is decomposed into silica gel (SiO2.nH2O) and CaCO3. As a result, concrete pore water pH decreases (usually below 10) and eventually steel reinforcing bars become unprotected from corrosion agents. Usually, the carbonation of the cementing matrix reduces the porosity, because CaCO3 crystals (calcite and vaterite) occupy more volume than portlandite. In this study, an accelerated carbonation-ageing process is conducted on Portland cement mortar samples with water to cement ratio of 0.5. The evolution of the carbonation process on mortar is monitored at different levels of ageing until the mortar is almost fully carbonated. A nondestructive technique based on nonlinear acoustic resonance is used to monitor the variation of the constitutive properties upon carbonation. At selected levels of ageing, the compressive strength is obtained. From fractured surfaces the depth of carbonation is determined with phenolphthalein solution. An image analysis of the fractured surfaces is used to quantify the depth of carbonation. The results from resonant acoustic tests revealed a progressive increase of stiffness and a decrease of material nonlinearity.

  11. Influence of bismuth oxide concentration on the pH level and biocompatibility of white Portland cement

    Directory of Open Access Journals (Sweden)

    Marina Angélica MARCIANO

    2014-07-01

    Full Text Available Objectives: To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement. Material and Methods: White Portland cement (WPC was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6. The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p0.05. For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05. The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (p<0.05. Conclusions: The addition of bismuth oxide into Portland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated.

  12. Effects of High Temperature on the Residual Performance of Portland Cement Concretes

    Directory of Open Access Journals (Sweden)

    Evandro Tolentino

    2002-09-01

    Full Text Available In this work we analyzed the "residual" performance of Portland cement concretes heat-treated at 600 °C after cooling down to room temperature. Concretes with characteristic compressive strength at 28 days of 45 MPa and of 60 MPa were studied. The heat-treatment was carried out without any imposed load. We measured the residual compressive strength and modulus of elasticity. The geometry of the structure was described by mercury intrusion porosimetry and nitrogen sorption tests. We observed a decrease of residual compressive strength and modulus of elasticity, with the raise of heat-treatment temperature, as a result of heat-induced material degradation. The results also indicated that the microstructural damage increased steadily with increasing temperature. Based on the results of this experimental work we concluded that residual mechanical properties of concrete are dependent of their original non heat-treated values.

  13. Standard Test Method for Bond Strength of Ceramic Tile to Portland Cement Paste

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2002-01-01

    1.1 This test method covers the determination of the ability of glazed ceramic wall tile, ceramic mosaic tile, quarry tile, and pavers to be bonded to portland cement paste. This test method includes both face-mounted and back-mounted tile. 1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  14. Effects of Two Redispersible Polymer Powders on Efflorescence of Portland Cement-based Decorative Mortar

    Directory of Open Access Journals (Sweden)

    Huimei ZHU

    2014-09-01

    Full Text Available The effects of redispersible polymer powders of ethylene/Vinyl acetate copolymer (EVA and ethylene/vinyl laurate/vinyl chloride terpolymer (E/VL/VC on the efflorescence of Portland cement-based decorative mortar (PCBDM were studied. The results showed that EVA slightly prolongs the efflorescence duration of fresh PCBDM; and exacerbates efflorescence of hardened PCBDM, because it increases the content of soluble salts such as Ca2+, K+, Na+ ions in hardened PCBDM and promotes their migration. E/VL/VC exacerbates efflorescence of fresh PCBDM due to it easily dissolves in the surface water; but reduces efflorescence of hardened PCBDM, which is attributed to that it decreases the soluble salts content in hardened PCBDM and prohibits salts migration. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.4053

  15. Influence of portland cement replacement in high calcium fly ash geopolymer paste

    Directory of Open Access Journals (Sweden)

    Tanakorn Phoo-ngernkham

    2014-03-01

    Full Text Available This article presents the influence of ordinary Portland cement (OPC replacement in high calcium fly ash (FA geopolymer paste. FA was used to replace OPC at the rate of 5, 10 and 15% by mass of binder. Sodium silicate (Na2SiO3 and 10 molar sodium hydroxide (NaOH solutions were used as the alkaline solution in the reaction. The Na2SiO3/NaOH ratio of 2.0 and the liquid/binder (L/B ratio of 0.60 were used in all mixtures. The results of increase OPC replacement, the setting time and compressive strain capacity decreased while the compressive strength and modulus of elasticity increased. The compressive strength and modulus of elasticity at 28 days of geopolymer pastes with 15% OPC replacement were 36.7 MPa and 13,300 MPa, respectively.

  16. Application of the fluorescence light microscopy in the textural study of portland cement clinker

    Directory of Open Access Journals (Sweden)

    Montoto San Miguel, Modesto

    1987-03-01

    Full Text Available The application of fluorescence light microscopy in the textural study of Portland cement clinker, specially its porosity, is presented. Principles and types of the technique are commented and the suggested sample preparation method is described. The use of fluorescence microscopy allows an easier study of the clinker porosity, and very proper images for automated quantification can be obtained. Besides, the samples can also be observed by reflected-light polarizing microscopy.

    Se presenta la utilidad de la microscopía óptica de fluorescencia para el estudio textural del clínker de cemento Portland, especialmente su porosidad. Se comentan los fundamentos y modalidades de la técnica, y se describe el método recomendado de preparación de muestras. La utilización de la microscopía de fluorescencia permite un estudio más fácil de la porosidad, obteniéndose imágenes muy apropiadas para su cuantificación mediante técnicas automatizadas. Además, las muestras para fluorescencia pueden ser estudiadas complementariamente por microscopía óptica de polarización por luz reflejada.

  17. Assessment of ferrous chloride and Portland cement for the remediation of chromite ore processing residue.

    Science.gov (United States)

    Jagupilla, Santhi C; Wazne, Mahmoud; Moon, Deok Hyun

    2015-10-01

    Chromite Ore Processing Residue (COPR) is an industrial waste containing up to 7% chromium (Cr) including up to 5% hexavalent chromium [Cr(VI)]. The remediation of COPR has been challenging due to the slow release of Cr(VI) from a clinker like material and thereby the incomplete detoxification of Cr(VI) by chemical reagents. The use of sulfur based reagents such as ferrous sulfate and calcium polysulfide to detoxify Cr(VI) has exasperated the swell potential of COPR upon treatment. This study investigated the use of ferrous chloride alone and in combination with Portland cement to address the detoxification of Cr(VI) in COPR and the potential swell of COPR. Chromium regulatory tests, X-ray powder diffraction (XRPD) analyses and X-ray absorption near edge structure (XANES) analyses were used to assess the treatment results. The treatment results indicated that Cr(VI) concentrations for the acid pretreated micronized COPR as measured by XANES analyses were below the New Jersey Department of Environmental Protection (NJDEP) standard of 20 mg kg(-1). The Toxicity characteristic leaching procedure (TCLP) Cr concentrations for all acid pretreated samples also were reduced below the TCLP regulatory limit of 5 mg L(-1). Moreover, the TCLP Cr concentration for the acid pretreated COPR with particle size ⩽0.010 mm were less than the universal treatment standard (UTS) of 0.6 mg L(-1). The treatment appears to have destabilized all COPR potential swell causing minerals. The unconfined compressive strength (UCS) for the treated samples increased significantly upon treatment with Portland cement.

  18. Regenerative Portland cement sorbents for fluidized-bed combustion of coal

    Energy Technology Data Exchange (ETDEWEB)

    Albanese, A S; Sethi, D; Steinberg, M

    1980-01-01

    Portland cements are commercially available construction materials that contain high concentrations of calcium silicates. The silicates are highly reactive towards SO/sub 2/ at temperatures and pressures encountered in atmospheric and pressurized FBC's. Of the Portland cements tested, PC III appears to have the highest sulfation capacity when sulfated by SO/sub 2/ at FBC conditions. A thermodynamic analysis of the sulfation of calcium silicates indicates that they are capable of reducing the concentration of SO/sub 2/ in FBC combustion gases to within the current EPA emission limits. The optimum temperature for sulfation of 16/20 mesh PC III pellets is about 1000/sup 0/C in comparison to about 875/sup 0/ for natural limestones. The higher observed optimum temperature is an advantage because combustion and power cycle efficiencies tend to increase as bed temperature increases. The reactions for regenerating sulfated calcium silicates are similar to those for regenerating calcium sulfate. However, the equilibrium partial pressures of SO/sub 2/ in the reductive decomposition of sulfated silicates are much higher than for sulfate lime. This implies that higher SO/sub 2/ concentrations will be attainable in the regenerator off-gas which will result in more economical conversion of SO/sub 2/ to sulfur or sulfuric acid. The sulfation capacity and regeneration efficiency of PC III pellets do not deteriorate with repeated sulfation/regeneration cycling. This indicates that PC III pellets are suitable for use in regenerative systems. The sulfation capacity of PC III is independent of pressure up to at least 10 atm.

  19. Marine durability of 15 year old concrete specimens made with ordinary portland, slag, and fly ash cements

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, T.U.; Yamaji, T.; Hamada, H. [Port and Harbor Research Inst., Ministry of Land, Infrastructure and Transport (Japan); Aoyama, T. [PS Corp. (Japan)

    2001-07-01

    A study was conducted in which the marine durability of ordinary portland cement, slag and fly ash cement was examined using 15 year old plain and reinforced concrete cylindrical specimens. In addition, the performance of these cements was also examined in another study for pre-cracked reinforced concrete prism samples. The process of manufacturing cement emits huge amounts of carbon dioxide into the global atmosphere. Replacing a portion of the cement with by-products from the steel industry and thermal power plants (which are both huge emitters of carbon dioxide) can lower carbon dioxide emissions and also solve the disposal issue of slag and fly ash while increasing the long-term durability of concrete structures. In this study, concrete cylindrical specimens were made of ordinary portland cement, slag and fly ash cements. Water-to-cement ratios were 0.45 and 0.55 and the compressive strength of the concrete, corrosion of the steel bars, and chloride-ion concentrations in the concrete were evaluated. It was shown that, with the exception of fly ash cements, the compressive strength of most cements increased after 15 years of exposure compared to its 28 day strength. Type C slag cement demonstrated the best performance against chloride-ion at the surface of concrete made with slag and fly ash. Voids in the steel-concrete interface make it possible for corrosion pits to develop. The use of seawater as mixing water results in earlier strength development at 28 days and does not cause to the strength of the concrete to regress after 15-years of exposure, but it causes more corrosion of steel bars at a lower cover depth. Corrosion of steel bars is not an issue at deeper cover depths. 15 refs., 18 tabs., 8 figs.

  20. The effect of portland cement for solidification of soils contaminated by mine tailings containing heavy metals

    Science.gov (United States)

    Jian-Jun, Chen; Zheng-Miao, Xie

    2010-05-01

    Portland cement(PC) was used to solidify the lead-zinc mine tailings contaminated soils(CS) in this work. The soils were heavily polluted by heavy metals with lead(up to 19592 mg/kg), zinc(up to 647mg/kg), Cd(up to 14.65mg.kg) and Cu(up to 287mg/kg). Solidified/stabilized(s/s)forms with a range of cement contents, 40-90 wt%, were evaluated to determine the optimal binder content. Unconfined compression strength test(UCS), Chinese solid waste-extraction procedure for leaching toxicity - Horizontal vibration method, toxicity characteristic leaching procedures(TCLP) were used for physical and chemical characterization of the s/s forms. The procedure of Tessier et al.(1979) was used to separate S/S forms Pb, Zn, Cd, Cu into different fractions. The results show that addition of 50% cement was enough for the s/s forms to satisfy the MU10 requirements (0.10 MPa). Under the 50% addition, the content of the water-exchangeable fraction of Pb reduced from 2.25% to 0.2%, the carbonate-bound fraction and organic-bound fraction reduced by about half, while the Fe-Mn oxide-bound fraction was more than doubled. The residual fraction decreased 8% on the contrary. For Zn, except for the carbonate-bound fraction increased slightly, the features of other items were same as that of Pb. For Cd, the water-exchangeable fraction was reduced largely, the residual fraction and Fe-Mn oxide-bound fraction increased 2-3%. For Cu, A distinct feature is the organic-bound fraction reduced with the reduction in consumption of cement, at the same time, the residual fraction increased corresponding. Leaching test results indicate that the leaching contents of Pb2+ of the six specimens are quite different at low pH value(

  1. Waste brick's potential for use as a pozzolan in blended Portland cement.

    Science.gov (United States)

    Lin, Kae-Long; Chen, Bor-Yann; Chiou, Chyow-San; An Cheng

    2010-07-01

    This study investigated the pozzolanic reactions and engineering properties of waste brick-blended cements in relation to various replacement ratios (0-50%). The waste brick consisted of SiO(2) (63.21%), Al(2)O(3) (16.41%), Fe(2)O(3) (6.05%), Na(2)O (1.19%), K(2)O (2.83%) and MgO (1.11%), and had a pozzolanic activity index of 107%. The toxic characteristic leaching procedure (TCLP) results demonstrate that the heavy-metal content in waste bricks met the Environmental Protection Agency regulatory limits. Experimental results indicate that 10, 20, 30, 40 and 50% of cement can be replaced by waste brick, which causes the initial and final setting times to increase. Compressive strength development was slower in waste brick-blended cement (WBBC) pastes in the early ages; however, strength at the later ages increased significantly. Species analyses demonstrate that the hydrates in WBBC pastes primarily consisted of Ca(OH)(2) and calcium silicate hydrate (C-S-H) gel, like those found in ordinary Portland cement (OPC) paste. Pozzolanic reaction products formed in the WBBC pastes, in particular, various reaction products, including hydrates of calcium silicates (CSH), aluminates (CAH) and aluminosilicates (CASH), formed as expected, resulting in consumption of Ca(OH)(2) during the late ages of curing. The changes in the properties of WBBC pastes were significant as blend ratio increased, due to the pores of C-S-H gels and CAH filling via pozzolanic reactions. This filling of gel pores resulted in densification and subsequently enhanced the gel/space ratio and degree of hydration. Experimental results demonstrate waste brick can be supplementary cementitious material.

  2. Properties of steel foundry electric arc furnace dust solidified/stabilized with Portland cement.

    Science.gov (United States)

    Salihoglu, Guray; Pinarli, Vedat; Salihoglu, Nezih Kamil; Karaca, Gizem

    2007-10-01

    Electric arc furnace dust from steel production is generated in considerable amounts worldwide and needs to be treated as hazardous waste. The aim of this study was to investigate the properties of electric arc furnace dust solidified/stabilized by using Portland cement. Mortar and paste samples were prepared with varying waste-to-binder ratios between 0% and 90%. A comprehensive experimental program was designed including XRF characterization, setting time, unconfined compressive strength, and toxicity characteristics leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), and acid neutralization capacity (ANC) tests. The results were evaluated in order to determine if the solidified /stabilized product can be disposed of at a landfill site with domestic waste or at a segregated landfill. The effect of using sand on S/S performance was also investigated. The results indicated that the solidification /stabilization process using PC helps the heavy metals to be bound in the cement matrix, but the TCLP leaching results exceeded the EPA landfilling limits. The SPLP leaching results conformed to the limits implying that the waste or S/S products can be disposed of at a segregated landfill; however the low ANC of the S/S products reveals that there may be leaching in the long-term. The sand used in the mortar samples adversely affected the S/S performance, causing higher heavy metal leaching levels, and lower pH levels in the leachate after the TCLP extraction than those measured in the leachate of the paste samples.

  3. The impact of sulphate and magnesium on chloride binding in Portland cement paste

    Energy Technology Data Exchange (ETDEWEB)

    De Weerdt, K., E-mail: klaartje.d.weerdt@ntnu.no [Department of Structural Engineering, Norwegian University of science and Technology, Trondheim (Norway); SINTEF Building and Infrastructure, Trondheim (Norway); Orsáková, D. [Department of Civil Engineering, Technical University of Brno, Brno (Czech Republic); Geiker, M.R. [Department of Structural Engineering, Norwegian University of science and Technology, Trondheim (Norway)

    2014-11-15

    The effect of magnesium and sulphate present in sea water on chloride binding in Portland cement paste was investigated. Ground well hydrated cement paste was exposed to MgCl{sub 2}, NaCl, NaCl + MgCl{sub 2}, MgSO{sub 4} + MgCl{sub 2} and artificial sea water solutions with a range of concentrations at 20 °C. Chloride binding isotherms are determined and pH of the solutions were measured. A selection of samples was examined by SEM-EDS to identify phase changes upon exposure. The experimental data were compared with calculations of a thermodynamic model. Chloride binding from sea water was similar to chloride binding for NaCl solutions. The magnesium content in the sea water lead to a slight decrease in pH, but this did not result in a notable increase in chloride binding. The sulphate present in sea water reduces both chloride binding in C–S–H and AFm phases, as the C–S–H incorporates more sulphates instead of chlorides, and part of the AFm phases converts to ettringite.

  4. Evolution and quantification of the main Sensitisers in commercial portland cements

    Directory of Open Access Journals (Sweden)

    Frías, M.

    2002-03-01

    Full Text Available The commercial Portland cements contain minor elements in their chemical compositions. The presence of these elements has a direct incidence in different aspects: rheological behaviour, reaction kinetics, environmental, etc. Some of them also have a negative effect on the human health; so, chromium (Cr, nickel (Ni and cobalt (Co are the main allergens present in Portland cements, causing of Professional Dermatitis in construction workers. The current study is focussed on the quantification of total and soluble chromium, nickel and cobalt in a wide range of Spanish commercial cements. These values can represent a contribution to the establishing of possible limitations or reductions of these elements in forthcoming standards. Analytical data show that clinkers are the main responsibles of the presence of soluble chromium in commercial cements. This fact could be indicating that chromium solubility (from inert Cr III to soluble Cr VI would be closely related to the clinkerisation conditions. On the other hand, there is not a direct ratio between total chromium and soluble chromium; it means that analytical results are punctual and not any case can be extrapolating ones. Ni and Co solubility in water is practically negligible either raw as clinkers.

    Los cementos Portland comerciales contienen elementos minoritarios en su composición química. La presencia de estos elementos tiene una incidencia directa en diferentes aspectos: comportamiento reológico, cinética de reacción, contaminación ambiental, etc. Algunos de ellos, aparte de su incidencia mencionada anteriormente, tienen un efecto negativo en la salud humana. Así, el cromo (Cr, níquel (Ni y cobalto (Co son los principales alérgenos contenidos en los cementos y, por lo tanto, los principales causantes de la Dermatitis Profesional. Este trabajo se centra en la cuantifîcación de los contenidos totales y solubles de cromo, níquel y cobalto presentes en los cementos comerciales

  5. Effectiveness of shrinkage-reducing admixtures on Portland pozzolan cement concrete

    Directory of Open Access Journals (Sweden)

    Videla, C.

    2005-06-01

    Full Text Available Drying shrinkage causes tensile stress in restrained concrete members. Since all structural elements are subject to some degree of restraint, drying shrinkage is regarded to be one of the main causes of concrete cracking. The purpose of the present study was to evaluate the effectiveness of SRA in reducing drying shrinkage strain in Portland pozzolan cement concrete. The major variables examined included slump, admixture type and dose, and specimen size. The measured results indicate that any of the admixtures used in the study significantly reduced shrinkage. Concrete manufactured with shrinkage reducing admixtures shrank an average of 43% less than concrete without admixtures. As a rule, the higher the dose of admixture, the higher was its shrinkage reduction performance. The experimental results were compared to the shrinkage strain estimated with the ACI 209, CEB MC 90, B3, GL 2000, Sakata 1993 and Sakata 2001 models. Although none of these models was observed to accurately describe the behaviour of Portland pozzolan cement concrete with shrinkage reducing admixtures, the Sakata 2001 model, with a weighted coefficient of variation of under 30%, may be regarded to be roughly adequate.

    La retracción por secado es un fenómeno intrínseco del hormigón que produce tensiones de tracción en elementos restringidos de hormigón. Puesto que todos los elementos presentan algún grado de retracción, se considera a la retracción por secado como una de las principales causas de agrietamiento en proyectos de construcción en hormigón. Por lo tanto, el objetivo de esta investigación fue evaluar la efectividad de los aditivos reductores de retracción (SRA en hormigones fabricados con cemento Portland puzolánico. Las variables principales estudiadas incluyen el asentamiento de cono de Abrams, marca y dosis de aditivo reductor de retracción, y tamaño de espécimen de hormigón. Los resultados obtenidos permiten concluir que el uso de

  6. Characterization of high-calcium fly ash and its influence on ettringite formation in portland cement pastes

    Science.gov (United States)

    Tishmack, Jody Kathleen

    High-calcium Class C fly ashes derived from Powder River Basin coal are currently used as supplementary cementing materials in portland cement concrete. These fly ashes tend to contain significant amounts of sulfur, calcium, and aluminum, thus they are potential sources of ettringite. Characterization of six high-calcium fly ashes originating from Powder River Basin coal have been carried out. The hydration products formed in pastes made from fly ash and water were investigated. The principal phases produced at room temperature were ettringite, monosulfate, and stratlingite. The relative amounts formed varied with the specific fly ash. Removal of the soluble crystalline sulfur bearing minerals indicated that approximately a third of the sulfur is located in the fly ash glass. Pore solution analyses indicated that sulfur concentrations increased at later ages. Three fly ashes were selected for further study based on their ability to form ettringite. Portland cement-fly ash pastes made with the selected fly ashes were investigated to evaluate ettringite and monosulfate formation. Each of the fly ashes were mixed with four different types of portland cements (Type I, I/II, II, and III) as well as three different Type I cements exhibiting a range of C3A and sulfate contents. The pastes had 25% or 35% fly ash by total weight of solids and a water:cement-fly ash ratio of 0.45. The samples were placed in a curing room (R.H. = 100, 23°C) and were then analyzed at various ages by x-ray diffraction (XRD) and differential scanning calorimetry (DSC) to determine the principal hydration products. The hydration products identified by XRD were portlandite, ettringite (an AFt phase), monosulfate, and generally smaller amounts of hemicarboaluminate and monocarboaluminate (all AFm phases). Although the amount of ettringite formed varied with the individual cement, only a modest correlation with cement sulfate content and no correlation with cement C3A content was observed. DSC

  7. Physical and mechanical characterization of Portland cement mortars made with expanded polystyrene particles addition (EPS

    Directory of Open Access Journals (Sweden)

    Ferrándiz-Mas, V.

    2012-12-01

    Full Text Available On this work the influence of the addition of different types (commercial and recycled and contents of expanded polystyrene on the physical and mechanical properties of Portland cement mortars has been studied. Variables studied are: workability, air content, bulk density, mechanical strength, porosity, water absorption and sound absorption. Mixtures have been also characterized by scanning electron microscopy. Air-entraining agents, water retainer and superplasticizer additives have been used in order to improve the workability of mortars. The results show that the workability and mechanical strength decreases with increasing content of expanded polystyrene. Additives improve the workability and porosity, allowing manufacture mortars with high levels of recycled material that show mechanical properties suitable for use as masonry mortars, stucco and plaster.

    El objetivo de este estudio es evaluar la influencia de la adición de distintos tipos y dosificaciones de poliestireno expandido, tanto comerciales como procedentes de reciclado, sobre las características físicas y mecánicas de morteros de cemento portland. Las variables estudiadas fueron: consistencia, aire ocluido, densidad aparente, resistencias mecánicas, porosidad, absorción de agua y absorción acústica. Los morteros también se han caracterizado por microscopia electrónica de barrido. Con objeto de mejorar la trabajabilidad de los morteros se ha empleado aditivos aireante, retenedor de agua y fluidificante. Los resultados muestran que al aumentar la cantidad de poliestireno expandido la trabajabilidad y las resistencias mecánicas disminuyen. El empleo de aditivos mejora la trabajabilidad y la porosidad, permitiendo fabricar morteros con altos contenidos de residuo, con propiedades mecánicas adecuadas para su empleo como morteros de albañilería, revoco y enlucido.

  8. Evaluation of the use of red mud as a pozzolanic additive in Portland cement; Avaliacao do uso de residuo de bauxita como aditivo pozolanico no cimento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Fortes, Gustavo Mattos; Balbino, Thiago Gabriel Ferreira; Lourenco, Rafaela Roberta; Rodrigues, Jose de Anchieta [Universidade Federal de Sao Carlos (GEMM/DEMa/UFSCar), Sao Carlos, SP (Brazil). Departamento de Engenharia de Materias. Grupo de Engenharia de Microestrutura de Materiais; Montini, Marcelo [Alcoa Aluminio S.A., Pocos de Caldas, MG (Brazil)

    2011-07-01

    It is estimated that the aluminum industry generates approximately 13.7 million tones/year of red mud (RB) in Brazil. Although, being the RB rich in Al{sub 2}O{sub 3} and SiO{sub 2} and partially amorphous, a potential pozzolanic activity is suggested. Thus, this work aims to evaluate the application of 15w-% of RB, as a pozzolanic additive, to the ordinary Portland cement (CPI), simulating a pozzolanic compost Portland cement (CPII-Z). To study the pozzolanic activation of the RB, this one was added without calcination, calcinated at 400°C and at 600°C. The compressive strength was measured in mortars of CPI with additions of RB, of CPI and CPII (references), after 28 days of curing. The analysis of the apparent porosity and the characterization of the hydration products were done to complement the evaluation. The mortars with calcinated RB showed good results of mechanical strength, reaching more than 85% (45 MPa) of the CPI's strength and higher values than the CPII-Z32. (author)

  9. Microstructure and mechanical properties of microwave-assisted heating of pozzolan-Portland cement paste at a very early stage

    OpenAIRE

    Natt Makul; Dinesh Kumar Agrawa

    2013-01-01

    Portland-pozzolan cement pastes at a very early stage subjecting to microwave heating were investigated. Microwave with a 2.45 GHz and multimode cavity was used for the experiments. The pastes containing pozzolan materials (pulverized fuel ash, metakaolin and silica fume) were proportioned with a 0.38 water/solid mass ratio and a 20% by weight replacement of total solid content. It was observed that the temperature increased continuously during microwave heating. Some ettringite rods and a...

  10. Combined effect of sodium sulphate and superplasticizer on the hydration of fly ash blended Portland® cement

    OpenAIRE

    Mukesh Kumar; Narendra Pratap Singh; Sanjay Kumar Singh; Nakshatra Bahadur Singh

    2010-01-01

    Combined effect of polycarboxylate type superplasticizer and sodium sulphate on the hydration of fly ash blended Portland® cement has been studied by using different techniques. Water consistency, setting times, non-evaporable water contents, water percolation, air contents, compressive strengths and expansion in corrosive atmosphere were determined. Hydration products were examined with the help of DTA and X-ray diffraction techniques. It is found that the superplasticizer reduces the pore s...

  11. Use of Variamine Blue dye in Spectrophotometric determination of Water Soluble Cr(VI in Portland Cement

    Directory of Open Access Journals (Sweden)

    Devesh K. Sharma

    2015-12-01

    Full Text Available Variamine blue dye as chromogenic reagent was used for Portland cement samples in determination of soluble hexavalent chromium. This method was based on the reaction of Cr(VI with potassium iodide in acidic medium to liberate iodine, which oxidized variamine blue to form a violet colored species having an absorption maximum 556 nm. The extraction of soluble Cr(VI for quantification in cement was done according to European method. The validity of this method was thoroughly examined by comparing with standard DPC method as well as the accuracy of the method was checked using a standard reference material of National Institute of Standards & Technology (NIST, USA.

  12. Environmental CRIteria for CEMent based products, ECRICEM. Phase I. Ordinary Portland Cements. Phase II. Blended Cements. Executive Summary

    Energy Technology Data Exchange (ETDEWEB)

    Van der Sloot, H.A.; Van Zomeren, A. [ECN Biomass, Coal and Environmetal Research, Petten (Netherlands); Stenger, R. [Holcim Group Support Ltd, Holderbank (Switzerland); Schneider, M.; Spanka, G. [VDZ, Duesseldorf (Germany); Stoltenberg-Hansson, A. [NORCEM, HeidelbergCement Group, Brevik (Norway); Dath, P. [Holcim Belgium, Obourg (Belgium)

    2008-01-15

    The protection of the immediate environment of structural works is one of the essential requirements of the European Construction Products Directive (CPD). According to the CPD, construction products can only be put on the market, if the structural works built with them fulfil the relevant requirements for hygiene, and the protection of health and the environment. These essential requirements in the respective standards are specified at the national level by the individual member states. Cement and cementitious materials are considered to fulfil the fundamental requirements of the European Construction Products Directive and the corresponding national regulations. Therefore a technical regulation like the cement standard EN 197 in general does not cover separate requirements for determining compliance of cementitious materials with criteria on hygiene, health and environmental protection. Further regulations are laid down in cases where it appears necessary for constructive applications requiring a particular protection of water, soil and air.

  13. Carbonation of low heat portland cement paste procured in water for different time

    Institute of Scientific and Technical Information of China (English)

    Deping Chen; Etsuo Sakai; Masaki Daimon; Yoko Ohba

    2007-01-01

    The carbonation technique was applied to accelerate the hydration of low heat portland cement (LHC). Before carbonation, the demoulded pastes were precured in water for 0, 2, 7, and 21 d, respectively. The results show that procuring time in water strongly influences the carbonation process. The phenolphthalein test indicates that the paste precured in water for a shorter time is more quickly carbonated than that for a longer time. The content of calcium hydroxide increases with increasing the procuring time in water, whereas, the amount of absorbed carbon dioxide changes contrarily. Scanning electron microscope (SEM) observation shows that portlandite always fills up big air bubbles in the paste during precuring in water, and the mercury intrusion porosimetry (MIP) results show that there are less large capillary pores in the paste precured in water for a longer time. It is found that the paste without precuring in water has more carbon dioxide absorption during curing in carbon dioxide atmosphere, and its total pore volume decreases remarkably with an increase in the carbonation time than that precured in water. X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) surface area analyses indicate that the carbonate products are vaterite and calcite; CxSHy,, formed from carbonation has low BET surface area in comparison with that of C-S-H formed from curing in water.

  14. Radiopacity and cytotoxicity of Portland cement associated with niobium oxide micro and nanoparticles

    Directory of Open Access Journals (Sweden)

    Leticia Boldrin MESTIERI

    2014-12-01

    Full Text Available Objective Mineral Trioxide Aggregate (MTA is composed of Portland Cement (PC and bismuth oxide (BO. Replacing BO for niobium oxide (NbO microparticles (Nbµ or nanoparticles (Nbη may improve radiopacity and bioactivity. The aim of this study was to evaluate the radiopacity and cytotoxicity of the materials: 1 PC; 2 White MTA; 3 PC+30% Nbµ; 4 PC+30% Nbη. Material and Methods For the radiopacity test, specimens of the different materials were radiographed along an aluminum step-wedge. For cell culture assays, Saos-2 osteoblastic-cells (ATCC HTB-85 were used. Cell viability was evaluated through MTT assay, and bioactivity was assessed by alkaline phosphatase activity assay. Results The results demonstrated higher radiopacity for MTA, followed by Nbµ and Nbη, which had similar values. Cell culture analysis showed that PC and PC+NbO associations promoted greater cell viability than MTA. Conclusions It was concluded that the combination of PC+NbO is a potential alternative for composition of MTA.

  15. Properties of high calcium fly ash geopolymer pastes with Portland cement as an additive

    Science.gov (United States)

    Phoo-ngernkham, Tanakorn; Chindaprasirt, Prinya; Sata, Vanchai; Pangdaeng, Saengsuree; Sinsiri, Theerawat

    2013-02-01

    The effect of Portland cement (OPC) addition on the properties of high calcium fly ash geopolymer pastes was investigated in the paper. OPC partially replaced fly ash (FA) at the dosages of 0, 5%, 10%, and 15% by mass of binder. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solutions were used as the liquid portion in the mixture: NaOH 10 mol/L, Na2SiO3/NaOH with a mass ratio of 2.0, and alkaline liquid/binder (L/B) with a mass ratio of 0.6. The curing at 60°C for 24 h was used to accelerate the geopolymerization. The setting time of all fresh pastes, porosity, and compressive strength of the pastes at the stages of 1, 7, 28, and 90 d were tested. The elastic modulus and strain capacity of the pastes at the stage of 7 d were determined. It is revealed that the use of OPC as an additive to replace part of FA results in the decreases in the setting time, porosity, and strain capacity of the paste specimens, while the compressive strength and elastic modulus seem to increase.

  16. A Binder of Phosphogypsum-Ground Granulated Blast Furnace Slag-Ordinary Portland Cement

    Institute of Scientific and Technical Information of China (English)

    HUANG Yun; LIN Zongshou

    2011-01-01

    A new hydraulic cementitious binder was developed by mainly utilizing industrial byproducts phosphogypsum (PG) and ground granulated blast furnace slag (GGBFS) with small addition of ordinary portland cement (OPC). The hydration process and microstructure were studied by X-ray diffraction (XRD)and scanning electronic microscopy (SEM). OPC hydrated first at early age to form primarily C-S-H gel, ettringite and calcium hydroxide (CH). GGBFS activated by CH and sulfate ions hydrated continuously at later age, producing more and more hydration products, C-S-H gel and ettringite. Thus the paste developed a denser microstructure and its strength increased. The 28 d compressive strength of the mixture of 50% PG, 46% GGBFS and 4% OPC exceeded 45 MPa. The setting time was faster and 3 d and 7 d strength were higher when the proportion of OPC increased. But the 28 d strength decreased when OPC exceeded 4% due to large amount of ettringite formed at late hydration age which damaged the microstructure.

  17. Microstructure and Composition of Hydration Products of Ordinary Portland Cement with Ground Steel-making Slag

    Institute of Scientific and Technical Information of China (English)

    LI Yong-xin; CHEN Yi-min; ZHANG Hong-tao; HE Xing-yang; WEI Jiang-xiong; ZHANG Wen-sheng

    2003-01-01

    The effect of ground steel-making slag on microstructure and composition of hydration products of ordinary Portland cement (OPC) was investigated by mercury intrusion porosimetry ( MIP ), X- ray diffraction (XRD) and differential thermal analysis (DTA). Results show that ground steel-making slag is a kind of high activity mineral additives and it can raise the longer-age strength of OPC mortar. The total porosity and average pore diameter of OPC paste with groand steel-making slag increase with the increase of the amount of ground steelmaking slag replacing OPC at various ages, while after 28 days most pores in OPC paste with ground steel-making slag do not influeace the strength because the diameter of those pores is in the rang of 20 to 50nm. The hydration mechanism of ground steel-making slag is similar to that of OPC but different from that of fly ash and blast furnace slag. The hydration products of ground steel-making slag contain quite a lot of Ca( OH)2 in long age.

  18. The use of Portland cement in the repair of mandibular fractures in rats Uso de cimento Portland no reparo de fratura mandibular em ratos

    Directory of Open Access Journals (Sweden)

    Reginaldo Inojosa Carneiro Campello

    2011-12-01

    Full Text Available PURPOSE: To evaluate the bone healing of mandibular fractures following the use of Portland cement. METHODS: Thirty-two male Wistar rats were divided into control and experimental groups. In the control group the rats were submitted to a mandibular fracture, which was reduced, and the soft tissues were sutured. In the experimental group the rats had the mandibular fracture reduced and maintained with the Portland cement. The animals were euthanized 7 and 21 days after surgery by injecting a lethal dose of anesthetic. The following variables were studied: weight of the animals, radiographic images, histopathological features and time of surgery. RESULTS: A weight loss was observed in the specimens of both groups at the different times of evaluation, a greater difference in weight before and after surgery being found in the experimental group, which was statistically significant (p OBJETIVO: Avaliar a reparação óssea de fratura mandibular após o uso do cimento Portland (CP. MÉTODOS: Trinta e dois ratos machos Wistar foram divididos em grupo controle e grupo experimental. No grupo controle os ratos foram submetidos à fratura, redução e manutenção dos seguimentos com sutura dos tecidos moles. No grupo experimental foram submetidos a fratura, redução e manutenção dos segmentos fraturados com CP e sutura dos tecidos. Os animais foram eutanasiados com sete e 21 dias de pós-operatório através da injeção de dose letal dos anestésicos adotados. As variáveis estudadas foram: peso dos animais, avaliação tomográfica, avaliação histológica e tempo cirúrgico. RESULTADOS: Perda de peso foi observada nos espécimes de ambos os grupos nos diferentes intervalos de tempo considerados, sendo maior a diferença de peso antes e após cirurgia para o grupo experimental, que foi estatisticamente significante (p<0,05; p=0,041. Do ponto de vista histológico para a margem de erro fixada (5,0% as duas únicas diferenças significativas (p<0

  19. Experimental determination of carbonation rate in Portland cement at 25°C and relatively high CO2 partial pressure

    Science.gov (United States)

    Hernández-Rodríguez, Ana; Montegrossi, Giordano; Huet, Bruno; Virgili, Giorgio; Orlando, Andrea; Vaselli, Orlando; Marini, Luigi

    2016-04-01

    The aim of this work is to study the alteration of Portland class G Cement at ambient temperature under a relatively high CO2 partial pressure through suitably designed laboratory experiments, in which cement hydration and carbonation are taken into account separately. First, the hydration process was carried out for 28 days to identify and quantify the hydrated solid phases formed. After the completion of hydration, accompanied by partial carbonation under atmospheric conditions, the carbonation process was investigated in a stirred micro-reactor (Parr instrument) with crushed cement samples under 10 bar or more of pure CO2(g) and MilliQ water adopting different reaction times. The reaction time was varied to constrain the reaction kinetics of the carbonation process and to investigate the evolution of secondary solid phases. Chemical and mineralogical analyses (calcimetry, chemical composition, SEM and X-ray Powder Diffraction) were carried out to characterize the secondary minerals formed during cement hydration and carbonation. Water analyses were also performed at the end of each experimental run to measure the concentrations of relevant solutes. The specific surface area of hydrated cement was measured by means of the BET method to obtain the rates of cement carbonation. Experimental outcomes were simulated by means of the PhreeqC software package. The obtained results are of interest to understand the comparatively fast cement alteration in CO2 production wells with damaged casing.

  20. Efeito do tempo de cura na rigidez de argamassas produzidas com cimento Portland Effect of the curing time on the stiffness of mortars produced with Portland cement

    Directory of Open Access Journals (Sweden)

    G. C. R. Garcia

    2011-03-01

    Full Text Available O concreto de cimento Portland é um dos materiais mais usados no mundo inteiro, entretanto, devido a sua estrutura ser muito complexa, torna-se imprescindível estudar suas propriedades com bastante profundidade. O concreto é produzido a partir de uma argamassa, de areia e cimento, com adição de agregados graúdos, sendo que suas propriedades estão basicamente suportadas nessa argamassa de constituição. O objetivo deste trabalho foi estudar a variação da rigidez de duas argamassas de composições com razão cimento:areia de 1:2 e 1:3 em função do tempo de cura, tendo como parâmetro a variação do módulo de Young. Os resultados mostraram que o módulo de Young cresce até atingir o valor máximo no oitavo dia, sendo que nos três primeiros dias esse crescimento é mais acentuado. A análise dos resultados indica que grande parte do processo de hidratação do cimento, com formação das ligações químicas responsáveis pela rigidez da argamassa, acontece nos primeiros dias de cura.Concrete produced with Portland cement is one of building materials most widely used worldwide. However, due to its highly complex structure, its properties require in-depth studies. Concrete is a mortar consisting of a mixture of cement, sand and coarse aggregates, and its properties are represented basically by the mortar base. The aim of this work was to study the change in stiffness of two mortar compositions cured at 25 ºC with a cement-to-sand ratio of 1:2 and 1:3, as a function of curing time using the variation of Young modulus as the measuring parameter. The results showed that Young modulus increases up to a maximum value on the 8th day, and that this increase is more pronounced during the first three days. An analysis of the results indicates that a large part of the cement hydration process, involving the formation of chemical bonds that are responsible for the mortar stiffness, takes place in the early days of curing.

  1. Reaction of CO2 and brine at the interface between Portland cement and casing steel: Application to CO2 sequestration

    Science.gov (United States)

    Carey, J. W.; Zhang, J.; Lichtner, P. C.; Grigg, R.; Svec, B.; Pawar, R.

    2008-12-01

    Prediction of CO2 leakage through wellbore systems is a multiscale problem in geologic sequestration. In order for wellbore leakage to occur, km-scale processes must deliver CO2 from the point of injection to the wellbore. But, in order for the wellbore to actually leak, μm-scale processes must operate to allow CO2 to flow up the wellbore. In this study, we describe experiments and modeling of microscale processes accompanying CO2 leakage along the cement-casing interface. This work fits within a broader predictive study of CO2 sequestration performance (Viswanathan et al. 2008, Env Sci and Tech, in press) that includes calculation of CO2-migration times to wellbores. Experiments carried out in this report consisted of synthetic wellbore systems constructed of Portland cement and casing-grade steel in which a mixture of CO2 and brine were forced along the cement-casing interface at in situ sequestration conditions (40 °C and 14 MPa). The CO2-brine mixture was pre- equilibrated by flow through limestone before encountering the cement-casing composite. (The limestone- equilibrated fluid was calculated to be strongly out of equilibrium with both cement and the casing.) We used a high CO2-brine flux (10-20 ml/hour along the interface) and hypothesized that the interface would widen with time due to dissolution of either or both cement and steel. In addition to experiments, we conducted reactive transport modeling of cement reactivity using FLOTRAN, which was modified to allow representation of solid solution in the dominant cement phase, calcium-silicate-hydrate. We also developed a corrosion model for the steel. The experimental results showed that the steel was more reactive than the Portland cement. Extensive deposits or oxidation products of FeCO3-rich material developed at the interface and in some places led to an apparent closure of the interface despite the large flux through the system. In contrast, alteration of the cement appeared to be limited by

  2. Potencialidades da metacaolinita e do tijolo queimado moído como substitutos parciais do cimento Portland Potentialities of metakaolin and crushed waste calcined clay brick as partial replacement of Portland cement

    Directory of Open Access Journals (Sweden)

    João de Farias Filho

    2000-12-01

    Full Text Available Avalia-se, neste trabalho, a potencialidade do uso da metacaolinita e dos resíduos de produção de tijolos cerâmicos queimados finamente moídos, como substitutos parciais do cimento Portland. Os materiais foram caracterizados física, química e mineralogicamente, além de determinado o índice de atividade pozolânica com cimento Portland. A evolução da resistência a compressão e a flexão das argamassas foi avaliada até as idades de, respectivamente, 365 e 208 dias. As porcentagens de substituição do cimento Portland, em peso, pelos materiais pozolânicos, variaram de 20 a 50%, enquanto o fator água/cimento variou de 0,37 a 0,45. Os resultados obtidos indicaram que a metacaolinita e o tijolo moído queimado possuem elevada atividade pozolânica e que a resistência a compressão, aos 28 dias, das argamassas mistas, foi superior à das argamassas de cimento Portland para os níveis de substituição e fatores água/cimento estudados. Um modelo matemático para predição da resistência à compressão das argamassas mistas é proposto com base em um desenho fatorial de experimentos.This paper evaluates the potentiality of metakaolin and crushed waste fired clay brick as cement replacement materials. They were characterised physically, chemically and mineralogically and their activity with Portland cement determined. The influence of the partial replacement of Portland cement on the development of compressive and flexural strength was evaluated until the age of, respectively, 365 and 208 days. The percentage of cement replacement, in weight, ranged from 20 to 50%, whereas the water/cement ratio ranged from 0.37 to 0.45. The results obtained show that the metakaolin and crushed calcined clay brick presented a good pozolanic activity and that the compressive strength of the blended mortars after 28 days of cure was higher than that observed for the reference Portland cement for all levels of cement replacement and water/cement ratio. A

  3. Quantitative determination of tricalcicum aluminate in portland cement by X-ray diffraction

    Directory of Open Access Journals (Sweden)

    Sagrera Moreno, José Luis

    1989-06-01

    Full Text Available Tricalcium aluminate (C3A is one of the constitutive phase of the cement-clinker. Its concentration influences the cement behaviour in sulphate aggressive soils. Therefore its quantification is very convenient and International standards fix its content when the concrete is used in contact with soils or liquids containing sulphate compounds. There are two possibilities in order to calculate the amount of C3A in clinker phases: one consist in a mathematical calculation from the results of the chemical analysis (Bogue formulae and the order is based in X-ray diffraction, using the height of the representative peak of the C3A phase. In the present note, the experimental procedure in order to determine the C3A content from X-ray test is presented.

    El aluminato tricáicico es una de las fases constitutivas del clinker de cemento portland. Su concentración en el cemento influye en el comportamiento de éste, en las obras sometidas a la posible agresividad de diferentes sulfatos cuando entran en contacto con las estructuras que se fabrican con él. Por ello la determinación de su concentración es un dato que puede invalidar su uso en una obra. De ahí que las normas internacionales fijen la cantidad de aluminato tricáicico según se clasifique la agresividad del entorno en el que una estructura será colocada. Existen fórmulas matemáticas para calcular la concentración de cada una de las fases del clinker a partir de las concentraciones de los elementos químicos de clinker expresados en forma de óxidos. Los posibles errores en los análisis químicos producen errores en los cálculos de las concentraciones de cada fase. Para determinar la concentración de dichas fases se puede emplear también la técnica de difracción de rayos X, basándose en la medida de la altura del pico representativo de la fase que se quiere determinar.

  4. The influence of energy mixing in pastes of Portland cement used in well cementing; Influencia da energia de mistura em pastas de cimento Portland utilizadas em cimentacao de pocos petroliferos

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Flank M.; Oliveira, Valeska G.; Martinelli, Antonio E.; Melo, Dulce M.A.; Cachina, Gustavo H.A.B. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2004-07-01

    Portland cement is by far the most important binding material used in oil well cementing. Its mixture process in field is one of the most important problems in well cementing practices. The objective of that process is to prepare the cement slurry with similar properties those found in preliminaries laboratory tests. That objective should be found, or else, the relevance of the calculations and tests accomplished to determine the displacement flow, friction pressure, thickening time and the fluid loss rate of cement slurry. It was verified that the mixture time increases significantly the energy of mixture of the pastes, provoking changes in the plastic viscosity, yield point and forces gel of pastes. The hydration rates of slurries were affected for the mixture conditions, causing a decrease of about 40% in thickening time. Measures of fluid loss evidenced that for larger mixture times happened a reduction of the percentile of free water of 4,2% to 0,0%, provoked by the increase of the reaction of the system. (author)

  5. Influence of the waste glass in the axial compressive strength of Portland cement concrete; Influencia dos residuos vitreos na resistencia a compressao axial do concreto de cimento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Miranda Junior, E.J.P.; Paiva, A.E.M., E-mail: edson.jansen@hotmail.com [Instituto Federal de Educacao, Ciencia e Tecnologia do Maranhao (PPGEM/IFMA), Sao Luis, MA (Brazil). Programa de Pos-Graduacao em Engenharia de Materiais

    2012-07-01

    In this work, was studied the influence of the incorporation of waste glass, coming from the stage of thinning and polishing of a company of thermal glass treatments, in the axial compressive strength of Portland cement concrete. The coarse and ground aggregates used was crushed stone and sand, respectively. For production of the concrete, percentages of glass residues of 5%, 10% and 20% had been used in substitution to the sand, and relations water/cement (a/c) 0,50, 0,55 and 0,58. The cure of the test bodies was carried through in 7, 14 and 28 days. The statistics analysis of the results was carried out through of the analysis of variance for each one of the cure times. From the results of the compressive strength of the concrete, it could be observed that the concrete has structural application for the relation a/c 0,5, independently of waste glass percentage used, and for the relation a/c 0,55 with 20% of waste glass. (author)

  6. Design and manufacture of Portland cement - application of sensitivity analysis in exploration and optimisation Part II. Optimisation

    DEFF Research Database (Denmark)

    Svinning, K.; Høskuldsson, Agnar

    2006-01-01

    A program for a model-based optimisation has been developed. The program contains two subprograms. The first one does minimising or maximising constrained by one original PLS-component or one equal to a combination of several. The second one does searching for the optimal combination of PLS......-components, which gives max or min y. The program has proved to be applicable for achieving realistic results for implementation in the design of Portland cement with respect to performance and in the quality control during production....

  7. Influence of natural pozzolan, colemanite ore waste, bottom ash, and fly ash on the properties of Portland cement

    Energy Technology Data Exchange (ETDEWEB)

    Targan, S.; Olgun, A.; Erdogan, Y.; Sevinc, V. [Dumlupinar University, Kutahya (Turkey). Dept. of Chemistry

    2003-08-01

    The effect of natural pozzolan (NP), colemanite ore waste (CW), coal fly ash (FA), and coal bottom ash (BA) on the properties of cement and concrete was examined. The parameters studied included compressive strength, bending strength, volume expansion, and setting time. A number of cements were prepared (in the presence of fixed quantity of 10% FA, 10% BA, and 4% CW) by the replacement of Portland cement (PC) with NP in range of 5 - 30%. The results showed that the final setting time of cement pastes were generally accelerated when the NP replaced part of the cement. However, NP exhibited a significant retarding effect when used in combination with CW. The results also showed that the inclusion of NP at replacement levels of 5% resulted in an increase in compressive strength of the specimens compared with that of the control concrete. The replacement of PC by 10 - 15% of NP in the presence of fixed quantity of CW improves the bending strength of the specimens compared with control specimens after 60 days of curing age.

  8. Cement Formation:A Success Story in a Black Box: High Temperature Phase Formation of Portland Cement Clinker

    OpenAIRE

    2012-01-01

    Cement production has been subject to several technological changes, each of which requires detailed knowledgeabout the high multiplicity of processes, especially the high temperature process involved in the rotary kiln. This article gives an introduction to the topic of cement, including an overview of cement production, selected cement properties, and clinker phase relations. An extended summary of laboratory-scale investigations on clinkerization reactions, the most important reactions in ...

  9. The radiation stability of ground granulated blast furnace slag/ordinary Portland cement grouts containing organic admixtures

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, J.D.; Fairhall, G.A. [British Nuclear Fuels, Sellafield (United Kingdom)

    1993-12-31

    At the British Nuclear Fuels (BNFL) Sellafield reprocessing plant in the United Kingdom, cement grouts based on ground granulated blast-furnace slag (BFS) and ordinary Portland cement (OPC) are used extensively for immobilizing radioactive wastes. These grouts have excluded organic admixtures in order to reduce process complexity and uncertainties, regarding the performance of organic admixtures with BFS/OPC grouts, particularly under irradiation. This study has investigated the effects of sulfonated melamine formaldehyde and naphthalene condensates on grout properties. The results show grout settlement and strengths increase on addition of additives, with the additives remaining largely in the pore solution. Under irradiation the additives breakdown liberating hydrogen and carbon dioxide. Strength and product dimensions are unaffected by irradiation.

  10. Evaluation of physical stability and leachability of Portland pozzolona cement (PPC) solidified chemical sludge generated from textile wastewater treatment plants.

    Science.gov (United States)

    Patel, Hema; Pandey, Suneel

    2012-03-15

    The chemical sludge generated from the treatment of textile dyeing wastewater is a hazardous waste as per Indian Hazardous Waste Management rules. In this paper, stabilization/solidification of chemical sludge was carried out to explore its reuse potential in the construction materials. Portland pozzolona cement (PPC) was selected as the binder system which is commercially available cement with 10-25% fly ash interground in it. The stabilized/solidified blocks were evaluated in terms of unconfined compressive strength, block density and leaching of heavy metals. The compressive strength (3.62-33.62 MPa) and block density (1222.17-1688.72 kg/m3) values as well as the negligible leaching of heavy metals from the stabilized/solidified blocks indicate that there is a potential of its use for structural and non-structural applications.

  11. Mossbauer Effect Study of the Hyper fine Structure of the Different Phases of Iron in the Portland Cement Produced in Qatar

    OpenAIRE

    Eissa, N. A. [نبيل عيسى; Sallam, H. A.; Al-Houty, L.; Al-Mauraikhy, M.

    1981-01-01

    Various samples of the raw materials used in the manufacture of Portland cement in Qatar, the clinker produced and the cement itself were studied by using Mossbauer Effect and X-ray diffraction analysis in order to investigate the hyperfine structure of the iron forms present and the distribution of these forms among the different phases of the cement. The results obtained revealed the presence of five forms of iron in the cement clinker (a) Fe3"1" ions in octahedral sites existed in the ferr...

  12. Microscopic air void analysis of hardened Portland cement concrete by the isolated shadow technique

    Science.gov (United States)

    Harris, Basil Mark

    The Isolated Shadow Technique is an image processing and analysis procedure for identifying and characterizing surface voids dispersed on an otherwise flat plane of heterogeneous solids. The objective of the Isolated Shadow Technique is to capture, process, and analyze images of a flat surface in which all of the features, save the boundary outlines of any surface voids, are eliminated. In short, the technique utilizes a series of digital images of the subject planar surface; where each image of the series is subjected to a unique lighting condition. By positioning the lights such that the shadows cast into the craters vary between images, these variations can be sequestered and the edges of the voids can subsequently be reconstructed from the isolated shadows. The primary purpose of this work was the development of the Isolated Shadow Technique for the particular application of quantitatively describing the microscopic voids in hardened Portland cement concrete. The Isolated Shadow System was developed for this application of the technique. The hardware and software of the system are described and the function is demonstrated. The system was found to have an average accuracy of 2.7% with a maximum deviation of 5.0% when compared to physical measurements. The results of polished sections of concrete specimens characterized by the Isolated Shadow System are compared to the results obtained with the commonly used standard methods (ASTM C 457; A and B). The coefficients of variation of parameters calculated to describe the air-void system (according to the ASTM C 457 formulations) are shown to be in the neighborhood of one percent when the observed test area includes at least 7,830 mmsp2 of polished concrete (with paste contents ranging from approximately 28% to 32%). The sensitivity of the air-void system parameters (as computed by the system) to changes in magnification and mosaic size are evaluated. A critical analysis of the underlying assumptions of the ASTM C

  13. Assessment of the interaction of Portland cement-based materials with blood and tissue fluids using an animal model

    Science.gov (United States)

    Schembri Wismayer, P.; Lung, C. Y. K.; Rappa, F.; Cappello, F.; Camilleri, J.

    2016-01-01

    Portland cement used in the construction industry improves its properties when wet. Since most dental materials are used in a moist environment, Portland cement has been developed for use in dentistry. The first generation material is mineral trioxide aggregate (MTA), used in surgical procedures, thus in contact with blood. The aim of this study was to compare the setting of MTA in vitro and in vivo in contact with blood by subcutaneous implantation in rats. The tissue reaction to the material was also investigated. ProRoot MTA (Dentsply) was implanted in the subcutaneous tissues of Sprague-Dawley rats in opposite flanks and left in situ for 3 months. Furthermore the material was also stored in physiological solution in vitro. At the end of the incubation time, tissue histology and material characterization were performed. Surface assessment showed the formation of calcium carbonate for both environments. The bismuth was evident in the tissues thus showing heavy element contamination of the animal specimen. The tissue histology showed a chronic inflammatory cell infiltrate associated with the MTA. MTA interacts with the host tissues and causes a chronic inflammatory reaction when implanted subcutaneously. Hydration in vivo proceeds similarly to the in vitro model with some differences particularly in the bismuth oxide leaching patterns. PMID:27683067

  14. Microstructure: Surface and cross-sectional studies of hydroxyapatite formation on the surface of white Portland cement paste in vitro

    Science.gov (United States)

    Chaipanich, Arnon; Torkittikul, Pincha

    2011-08-01

    The formation of hydroxyapatite was investigated at the surface and at the cross-section of white Portland cement paste samples before and after immersion in simulated body fluid. Scanning electron microscope images showed that hydroxyapatite were found at the surface of white Portland cement after immersion in simulated body fluid. Hydroxyapatite grains of mostly ≈1 μm size with some grain size of ≈2-3 μm were seen after 4 days immersion period. More estabilshed hydroxyapatite grain size of ≈3 μm grains were observed at longer period of immersion at 7 and 10 days. The cross-section of the samples was investigated using line scanning technique and was used to determine the hydroxyapatite layer. A strong spectrum of phosphorus is detected up to 6-8 μm depth for samples after 4, 7 and 10 days immersion in simulated body fluid when compared to weak spectrum detected before immersion. The increase in the phosphorus spectrum corresponds to the hydroxyapatite formation on the surface of the samples after the samples were placed in simulated body fluid.

  15. Microstructure and mechanical properties of microwave-assisted heating of pozzolan-Portland cement paste at a very early stage

    Directory of Open Access Journals (Sweden)

    Natt Makul

    2013-12-01

    Full Text Available Portland-pozzolan cement pastes at a very early stage subjecting to microwave heating were investigated. Microwave with a 2.45 GHz and multimode cavity was used for the experiments. The pastes containing pozzolan materials (pulverized fuel ash, metakaolin and silica fume were proportioned with a 0.38 water/solid mass ratio and a 20% by weight replacement of total solid content. It was observed that the temperature increased continuously during microwave heating. Some ettringite rods and amorphous C-S-H fibers appear at 4 hrs. The metakaolin-cement paste exhibited little difference between the watercured and microwave-cured pastes. For the silica fume-cement paste the SF particles under microwave curing had dispersed more than with the 4 hr–cement paste. The produced phases included calcium silicate hydrate, calcium hydroxide and xenotile. The pastes can be developed in compressive strength quite rapidly and also consumed more Ca(OH2 in the pozzolan reaction to produce more C-S-H.

  16. Manufacturing of mortars and concretes non-traditionals, by Portland cement, metakaoline and gypsum (15.05%

    Directory of Open Access Journals (Sweden)

    Talero, R.

    1999-12-01

    Full Text Available In a thorough previous research (1, it appeared that creation, evolution and development of the values of compressive mechanical strength (CS and flexural strength (FS, measured in specimens 1x1x6cm of mortar type ASTM C 452-68 (2, manufactured by ordinary Portland cement P-1 (14.11% C3A or PY-6 (0.00% C3A, metakaolin and gypsum (CaSO4∙2H2O -or ternary cements, CT-, were similar to the ones commonly developed in mortars and concretes of OPC. This paper sets up the experimental results obtained from non-traditional mortars and concretes prepared with such ternary cements -TC-, being the portland cement/metakaolin mass ratio, as follows: 80/20, 70/30 and 60/40. Finally, the behaviour of these cements against gypsum attack, has been also determined, using the following parameters: increase in length (ΔL%, compressive, CS, and flexural, FS, strengths, and ultrasound energy, UE. Experimental results obtained from these non-traditional mortars and concretes, show an increase in length (ΔL, in CS and FS, and in UE values, when there is addition of metakaolin.

    En una exhaustiva investigación anterior (1, se pudo comprobar que la creación, evolución y desarrollo de los valores de resistencias mecánicas a compresión, RMC, y flexotracción, RMF, proporcionados por probetas de 1x1x6 cm, de mortero 1:2,75, selenitoso tipo ASTM C 452-68 (2 -que habían sido preparadas con arena de Ottawa, cemento portland, P-1 (14,11% C3A o PY- 6 (0,00% C3A, metacaolín y yeso (CaSO4∙2H2O-, fue semejante a la que, comúnmente, desarrollan los morteros y hormigones tradicionales de cemento portland. En el presente trabajo se exponen los resultados experimentales obtenidos de morteros y hormigones no tradicionales, preparados con dichos cementos ternarios, CT, siendo las proporciones porcentuales en masa ensayadas, cemento portland/metacaolín, las siguientes: 80/20, 70

  17. High-resolution synchrotron powder diffraction analysis of ordinary Portland cements: Phase coexistence of alite

    Science.gov (United States)

    de la Torre, Ángeles G.; Losilla, Enrique R.; Cabeza, Aurelio; Aranda, Miguel A. G.

    2005-08-01

    The mineralogical composition of four commercial and NIST RM-8488 Portland clinkers have been analysed by Rietveld methodology using high-resolution synchrotron X-ray powder diffraction data. Alite phase coexistence has been observed in four patterns. White Portland clinkers show a single alite or a very small amount of a second alite with smaller volume due to higher magnesium content. Grey Portland clinkers show a much pronounced alite phase coexistence which has been related to higher magnesium contents. Details about these analyses are given. Furthermore, the full mineralogical composition (including the non-diffracting content) has been determined from the overestimation of the added standard, α-Al2O3, in the Rietveld analyses. White clinkers contain ∼15 wt.% of non-diffracting content while this fraction is much smaller in grey clinkers, ∼7 wt.%.

  18. High-resolution synchrotron powder diffraction analysis of ordinary Portland cements: Phase coexistence of alite

    Energy Technology Data Exchange (ETDEWEB)

    Torre, Angeles G. de la [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain); Losilla, Enrique R. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain); Cabeza, Aurelio [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain); Aranda, Miguel A.G. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain)]. E-mail: g_aranda@uma.es

    2005-08-15

    The mineralogical composition of four commercial and NIST RM-8488 Portland clinkers have been analysed by Rietveld methodology using high-resolution synchrotron X-ray powder diffraction data. Alite phase coexistence has been observed in four patterns. White Portland clinkers show a single alite or a very small amount of a second alite with smaller volume due to higher magnesium content. Grey Portland clinkers show a much pronounced alite phase coexistence which has been related to higher magnesium contents. Details about these analyses are given. Furthermore, the full mineralogical composition (including the non-diffracting content) has been determined from the overestimation of the added standard, {alpha}-Al{sub 2}O{sub 3}, in the Rietveld analyses. White clinkers contain {approx}15 wt.% of non-diffracting content while this fraction is much smaller in grey clinkers, {approx}7 wt.%.

  19. A Histologic Evaluation on Tissue Reaction to Three Implanted Materials (MTA, Root MTA and Portland Cement Type I in the Mandible of Cats

    Directory of Open Access Journals (Sweden)

    F. Sasani

    2004-09-01

    Full Text Available Statement of Problem: Nowadays Mineral Trioxide aggregate (MTA is widely used for root end fillings, pulp capping, perforation repair and other endodontic treatments.Investigations have shown similar physical and chemical properties for Portland cement and Root MTA with those described for MTA.Purpose: The aim of this in vitro study was to evaluate the tissue reaction to implanted MTA, Portland cement and Root MTA in the mandible of cats.Materials and Methods: Under asepsis condition and general anesthesia, a mucoperiosteal flap, following the application of local anesthesia, was elevated to expose mandibular symphysis. Two small holes in both sides of mandible were drilled. MTA, Portland cement and Root MTA were mixed according to the manufacturers, recommendation and placed in bony cavities. In positive control group, the test material was Zinc oxide powder plus tricresoformalin. In negative control group, the bony cavities were left untreated. After 3,6 and 12 weeks, the animals were sacrificed and the mandibular sections were prepared for histologic examination under light microscope. The presence and thickness of inflammation, presence of fibrosis capsule, the severity of fibrosis and bone formation were investigated. The data were submitted to Exact Fisher test, chi square test and Kruskal-Wallis test for statistical analysis.Results: No statistically significant differences were found in the degree of inflammation,presence of fibrotic capsule, severity of fibrosis and inflammation thickness between Root MTA, Portland cement and MTA (P>0.05. There was no statistical difference in boneformation between MTA and Portland cement (P>0.05. However, bone formation was not found in any of the Root MTA specimens and the observed tissue was exclusively of fibrosis type.Conclusion: The physical and histological results observed with MTA are similar to those of Root MTA and Portland cement. Additionally, all of these three materials are biocompatible

  20. Effect of mixes made of coal bottom ash and fly ash on the mechanical strength and porosity of Portland cement

    Directory of Open Access Journals (Sweden)

    Argiz, C.

    2013-03-01

    Full Text Available New additions to the cement are needed to achieve a more sustainable and durable construction material. Within this context, bottom ashes can be used as a main constituent of Portland cements when it is mixed in an optimized proportion with fly ashes. The mechanical characteristics of standarized mortars made of mixes of pulverized coal combustion bottom and fly ashes are studied. The mortars were made of ordinary Portland cement (CEM I 42.5 N and mixes of bottom ashes with fly ashes in similar proportions to those of CEM II/A-V, CEM II/B-V and CEM IV/A (V. Summing up, it can be said that the utilization of bottom ashes mixed with fly ashes in replacement levels from 0% to 100% do not affect significantively on the mechanical caracteristics of the mortars considered in the present study which had an addition maximum content of 35%.

    La utilización de nuevas adiciones en el cemento es necesaria con el fin de obtener un material más sostenible y durable. En este sentido, las cenizas de fondo o cenicero de las centrales termoeléctricas de carbón se podrían reciclar siendo empleadas como un componente principal de los cementos Portland. Se han estudiado las propiedades mecánicas de unos morteros normalizados elaborados con mezclas de cenizas volantes con cenizas de fondo fabricados con unos porcentajes similares a los correspondientes de los CEM II/A-V, CEM II/B-V y CEM IV/A (V. En conclusión, la utilización de mezclas de cenizas de fondo o cenicero con cenizas volantes sustituyendo a éstas últimas entre el 0% y el 100%, no influye significativamente en el comportamiento mecánico de los morteros estudiados en los que el contenido máximo de adición ha sido del 35%, si bien afecta a determinados aspectos microestructurales, como la cantidad y distribución de poros capilares.

  1. Effects of chemical and mineral additives and the water/cement ratio on the thermal resistance of Portland cement concrete; O efeito de aditivos quimicos e minerais e da relacao agua/cimento na resistencia ao calor do concreto de concreto de cimento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Cesar, Leandro Cesar Dias; Morelli, Arnaldo C.; Baldo, Joao Baptista [Sao Carlos Univ., SP (Brazil). Dept. de Engenharia de Materiais

    1998-07-01

    The exposure of Portland concrete to high temperatures (>250 deg C) can damage drastically the microstructural integrity of the material. Since the water/cement ratio as well as the inclusion of superplasticizers and mineral additives (silica fume) can alter constitutively and micro structurally the material, in this work it was investigated per effect of these additions on the damage resistance of portland concrete after exposure to high temperatures. (author)

  2. Influence of mixture ratio and pH to solidification/stabilization process of hospital solid waste incineration ash in Portland cement.

    Science.gov (United States)

    Sobiecka, Elzbieta; Obraniak, Andrzej; Antizar-Ladislao, Blanca

    2014-09-01

    Solidification/stabilization (S/S) is an established utilization technology to treat hazardous wastes. This research explored the influence of pH (3-12) on the immobilization of heavy metals present in five mixtures of hospital solid waste incinerator ash and Portland cement, following two different processes of waste solidification/stabilization (cement hydration and granulation). In general, cement hydration process resulted in more stable products than granulation process. A high ash content in the mixture with Portland cement (60wt%) resulted in the highest immobilization of Pb(2+) and Cu(2+), while a low ash content in the mixture (10wt%) resulted in the lowest leachability of Zn(2+). When ash and Portland cement was mixed in equal proportions (50wt%) the highest encapsulation was observed for Ni(2+), Cd(2+) and Cr(3+). Neutral and weak alkaline pH values within the range pH=7-8 resulted in the lowest leachability of the monitored heavy metals.

  3. Determination of strontium and simultaneous determination of strontium oxide, magnesium oxide and calcium oxide content of Portland cement by derivative ratio spectrophotometry.

    Science.gov (United States)

    Idriss, K A; Sedaira, H; Ahmed, S S

    2009-04-15

    A derivative spectrophotometric method has been developed for the determination of strontium in Portland cement. The method is applied successfully for the simultaneous determination of SrO, MgO and CaO. It is based on the use of Alizarin Complexone (AC) as a complexing agent and measurement of the derivative ratio spectra of the analytes. Interferences of manganese(II) and zinc(II) were eliminated by precipitation. The validity of the method was examined by analyzing several Standard Reference Material (SRM) Portland cement samples. The strontium complex formed at pH 9.5 allows precise and accurate determination of strontium over the concentration range of 1.5-18 mg L(-1) of strontium. The MDL (at 95% confidence level) was found to be 25 ng mL(-1) for strontium in National Institute of Standards and Technology (NIST) cement samples using the proposed method.

  4. Adsorption of cefixime from aqueous solutions using modified hardened paste of Portland cement by perlite; optimization by Taguchi method.

    Science.gov (United States)

    Rasoulifard, Mohammad Hossein; Khanmohammadi, Soghra; Heidari, Azam

    In the present study, we have used a simple and cost-effective removal technique by a commercially available Fe-Al-SiO2 containing complex material (hardened paste of Portland cement (HPPC)). The adsorbing performance of HPPC and modified HPPC with perlite for removal of cefixime from aqueous solutions was investigated comparatively by using batch adsorption studies. HPPC has been selected because of the main advantages such as high efficiency, simple separation of sludge, low-cost and abundant availability. A Taguchi orthogonal array experimental design with an OA16 (4(5)) matrix was employed to optimize the affecting factors of adsorbate concentration, adsorbent dosage, type of adsorbent, contact time and pH. On the basis of equilibrium adsorption data, Langmuir, Freundlich and Temkin adsorption isotherm models were also confirmed. The results showed that HPPC and modified HPPC were both efficient adsorbents for cefixime removal.

  5. Analysis by X-Ray images of EVA waste incorporated in Portland Cement; Analise atraves de imagens de raios X da incorporacao de residuo de EVA em cimento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Marques, M.A.; Antunes, M.L.P.; Montagnoli, R.M.; Mancini, S.D., E-mail: marciomq@sorocaba.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Sorocaba, SP (Brazil)

    2012-07-01

    The EVA is a copolymer used by Brazilian shoes industries. This material is cut for the manufacture of insoles. This operation generates about 18% of waste. The EVA waste can be reused in incorporation in Portland cement to construction without structural purposes. The aim of this work is to show X-rays images to assessment the space distribution of the wastes in the cement and to evaluate the use of this methodology. Cylindrical specimens were produced according to ABNT - NBR 5738 standards. The volume relation of sand and cement was 3:1, 10% and 30% of waste was incorporated in cement specimens. X-Rays images were obtained of cylindrical specimens in front projection. The images showed that the distribution of the waste is homogeneous, consistent with what was intended in this type of incorporation, which can provide uniformity in test results of compressive strength. (author)

  6. Mitigating the effects of system resolution on computer simulation of Portland cement hydration

    NARCIS (Netherlands)

    Chen, W.; Brouwers, H.J.H.

    2008-01-01

    CEMHYD3D is an advanced, three-dimensional computer model for simulating the hydration processes of cement, in which the microstructure of the hydrating cement paste is represented by digitized particles in a cubic domain. However, the system resolution (which is determined by the voxel size) has a

  7. Study of the relation between hydrated portland cement composition and leaching resistance

    NARCIS (Netherlands)

    Eijk, van R.J.; Brouwers, H.J.H.

    1998-01-01

    The present paper addresses cement compositions that have an optimal resistance against acid attack and hence, low leaching rates and optimal waste containment. To this end a shrinking core leaching model is used that describes the leaching of metals from a cement sample. This process is directly re

  8. Long-term modeling of glass waste in portland cement- and clay-based matrices

    Energy Technology Data Exchange (ETDEWEB)

    Stockman, H.W.; Nagy, K.L. [Sandia National Labs., Albuquerque, NM (United States); Morris, C.E. [Wollongong Univ., NSW (Australia). Dept. of Civil and Mining Engineering

    1995-12-01

    A set of ``templates`` was developed for modeling waste glass interactions with cement-based and clay-based matrices. The templates consist of a modified thermodynamic database, and input files for the EQ3/6 reaction path code, containing embedded rate models and compositions for waste glass, cement, and several pozzolanic materials. Significant modifications were made in the thermodynamic data for Th, Pb, Ra, Ba, cement phases, and aqueous silica species. It was found that the cement-containing matrices could increase glass corrosion rates by several orders of magnitude (over matrixless or clay matrix systems), but they also offered the lowest overall solubility for Pb, Ra, Th and U. Addition of pozzolans to cement decreased calculated glass corrosion rates by up to a factor of 30. It is shown that with current modeling capabilities, the ``affinity effect`` cannot be trusted to passivate glass if nuclei are available for precipitation of secondary phases that reduce silica activity.

  9. Translational and rotational dynamics of water contained in aged Portland cement pastes studied by quasi-elastic neutron scattering.

    Science.gov (United States)

    Li, Hua; Zhang, Li-Li; Yi, Zhou; Fratini, Emiliano; Baglioni, Piero; Chen, Sow-Hsin

    2015-08-15

    Cement is a widely used construction material in the world. The quality and durability of aged cement pastes have a strong relationship with the water contained in it. The translational and rotational dynamics of water in ordinary Portland cement (OPC) pastes cured for 7, 14 and 30days were studied by analyzing Quasi-elastic Neutron Scattering (QENS) data. The effect of a new super-plasticizer (SP) additive was also studied by comparing the samples with and without the additive. By fitting the QENS spectra with the Jump-diffusion and Rotation-diffusion Model (JRM), six important parameters including the bound water index (BWI), the self-diffusion coefficient, D(t), the average residence time, τ0, the rotational diffusion constant, D(r), the rotational residence time, τ(r), and the mean squared displacement (MSD), 〈u(2)〉, were obtained. From these parameters, we can quantitatively follow the evolution of the bound water fraction (BWI). We can clearly see the different time ranges for the translational and rotational dynamics of water contained in the OPC pastes by τ0 and τ(r). From the MSD values compared with those of molecular dynamics simulation, we can distinguish between immobile water (mainly bound water) and mobile water, which includes confined water and ultraconfined water. Furthermore, by the fitted parameters' values and their change of slopes with increasing setting time for cement pastes with and without additive SP, it becomes clear that the effect of additive SP is to make the mobile water more confined and induce a more uniform the aging process during the evolution of the OPC pastes.

  10. Corrosion rate of steel embedded in blended Portland and fluid catalytic cracking catalyst residue (FC3R cement mortars

    Directory of Open Access Journals (Sweden)

    Payá, J.

    2008-12-01

    Full Text Available This paper reports on a study of the corrosion levels in steel bars embedded in mortars made with a blend of Portland cement and (0-20% spent fluid catalytic cracking catalyst residue (FC3R, with a variable (0.3-0.7 water/binder (w/b ratio. The specimens were stored in the following conditions: relative humidity of 40, 80 or 100% and CO2 concentrations of 5 and 100%. The steel corrosion rate was measured with polarization resistance techniques. In the absence of aggressive agents, the steel was found to remain duly passivated in mortars with an FC3R content of up to 15% under all the conditions of relative humidity tested. The reinforcement corrosion level in mortars with a w/b ratio of 0.3 and 15% FC3R subjected to accelerated carbonation was similar to the level observed in the unblended Portland cement control mortar.En este trabajo se ha estudiado el nivel de corrosión de barras de acero embebidas en morteros de cemento Portland con relación agua/material cementante (a/mc variable (0,3-0,7, en los que parte del cemento (0-20% se sustituyó por catalizador de craqueo usado (FC3R. Las condiciones de conservación de las probetas elaboradas fueron las siguientes: distintas humedades relativas (40, 80 y 100% y dos concentraciones de CO2 (5 y 100%. La velocidad de corrosión de los aceros se midió mediante la técnica de resistencia de polarización. Se ha podido determinar que, bajo las distintas condiciones de humedad relativa y ausencia de agresivo, los aceros se mantuvieron correctamente pasivados en los morteros con contenidos de FC3R de hasta el 15%. El nivel de corrosión que presenta el refuerzo embebidos en morteros con sustitución de un 15% de cemento por FC3R y relación a/mc 0,3, al ser sometidos a un proceso de carbonatación acelerada, era muy similar al mostrado por el mortero patrón, sin FC3R.

  11. Chloride adsorption by calcined layered double hydroxides in hardened Portland cement paste

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Seyoon [School of Engineering, Kings College, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Moon, Juhyuk, E-mail: juhyuk.moon@stonybrook.edu [Civil Engineering Program, Department of Mechanical Engineering, State University of New York at Stony Brook, New York 11794 (United States); Bae, Sungchul [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States); Duan, Xiaonan [Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853 (United States); Giannelis, Emmanuel P. [Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853 (United States); Center for Refining and Petrochemicals, The Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Monteiro, Paulo M. [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States)

    2014-06-01

    This study investigated the feasibility of using calcined layered double hydroxides (CLDHs) to prevent chloride-induced deterioration in reinforced concrete. CLDHs not only adsorbed chloride ions in aqueous solution with a memory effect but also had a much higher binding capacity than the original layered double hydroxides (LDHs) in the cement matrix. We investigated this adsorption in hardened cement paste in batch cultures to determine adsorption isotherms. The measured and theoretical binding capacities (153 mg g{sup −1} and 257 mg g{sup −1}, respectively) of the CLDHs were comparable to the theoretical capacity of Friedel's salt (2 mol mol{sup −1} or 121 mg g{sup −1}), which belongs to the LDH family among cementitious phases. We simulated chloride adsorption by CLDHs through the cement matrix using the Fickian model and compared the simulation result to the X-ray fluorescence (XRF) chlorine map. Based on our results, it is proposed that the adsorption process is governed by the chloride transport through the cement matrix; this process differs from that in an aqueous solution. X-ray diffraction (XRD) analysis showed that the CLDH rebuilds the layered structure in a cementitious environment, thereby demonstrating the feasibility of applying CLDHs to the cement and concrete industries. - Highlights: • We examine the adsorption equilibrium and kinetics of CLDH in the hydrated cement. • CLDH capacity to bind chloride ions in the hydrated cement paste is determined. • We model chloride adsorption by CLDH through the cement matrix. • CLDH reforms the layered structure with ion adsorption in the cement matrix.

  12. Examples of cooler reflective streets for urban heat-island mitigation : Portland cement concrete and chip seals

    Energy Technology Data Exchange (ETDEWEB)

    Pomerantz, M.; Akbari, H.; Chang, S.-C.; Levinson, R.; Pon, B.

    2003-04-30

    Part of the urban heat island effect can be attributed to dark pavements that are commonly used on streets and parking lots. In this paper we consider two light colored, hence cooler, alternative paving materials that are in actual use in cities today. These are Portland cement concrete (PCC) pavements and chip seals. We report measurements of the albedos of some PCC and chip sealed pavements in the San Francisco Bay Area. The albedos of the PCC pavements ranged from about 0.18 to 0.35. The temperatures of some PCC pavements are also measured and calculated. We then consider how the albedos of the constituent materials of the PCC (stone, sand and cement) contribute to the albedos of the resulting finished concrete. The albedos of a set of chip sealed pavements in San Jose, CA, were measured and correlated with the times of their placement. It is found that the albedos decrease with age (and use) but remain higher than that of standard asphalt concrete (AC) for about five years. After t hat, the albedos of the chip seals are about 0.12, similar to aged AC. The fact that many PCC pavements have albedos at least twice as high as aged AC suggests that it is possible to have pavement albedos that remain high for many years.

  13. Follow up of the glassy phase formation as silicon oxide was added to Brownmillerite phase of Portland cement clinker

    Energy Technology Data Exchange (ETDEWEB)

    Hassaan, M. Y., E-mail: yousry@tedata.net.eg; Salem, S. M.; Ebrahim, F. M. [Al-Azhar University, Moessbauer Lab, Physics Department, Faculty of Science (Egypt)

    2009-01-15

    Brownmillerite phase is one of the four main phases of Portland cement clinker. It was prepared as pure C{sub 4}AF{sup 1} and C{sub 4}AF with different amount of SiO{sub 2}, (5, 10, 15, 20, 25, and 40 mol%) by addition. Pure C{sub 4}AF was prepared using CaO, Al{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} according to the ratios 4:1:1. Each sample mixture was fired at 1,400 deg. C for 1 h then ground and introduced again to 1,400 deg. C for 1/2 h then quenched in air. The prepared samples were ground and measured using x-ray diffraction, scanning electron microscope, A.C. conductivity and Moessbauer spectroscopy. The results were correlated and discussed. The main finding is the formation of a glassy phase besides the C{sub 4}AF structure, in addition to the formation of the C{sub 2}S phase of cement clinker as SiO{sub 2} addition was upgraded. The electrical conductivity results showed that the 20 mol% SiO{sub 2} sample has the lowest ({sigma}) value.

  14. In vitro cytotoxicity of white MTA, MTA Fillapex® and Portland cement on human periodontal ligament fibroblasts.

    Science.gov (United States)

    Yoshino, Patrícia; Nishiyama, Celso Kenji; Modena, Karin Cristina da Silva; Santos, Carlos Ferreira; Sipert, Carla Renata

    2013-01-01

    The aim of this study was to compare the in vitro cytotoxicity of white mineral trioxide aggregate (MTA), MTA Fillapex® and Portland cement (PC) on human cultured periodontal ligament fibroblasts. Periodontal ligament fibroblast culture was established and the cells were used for cytotoxic tests after the fourth passage. Cell density was set at 1.25 X10 4 cells/well in 96-well plates. Endodontic material extracts were prepared by placing sealer/cement specimens (5x3mm) in 1mL of culture medium for 72 h. The extracts were then serially two-fold diluted and inserted into the cell-seeded wells for 24, 48 and 72 h. MTT assay was employed for analysis of cell viability. Cell supernatants were tested for nitric oxide using the Griess reagent system. MTA presented cytotoxic effect in undiluted extracts at 24 and 72 h. MTA Fillapex® presented the highest cytotoxic levels with important cell viability reduction for pure extracts and at ½ and ¼ dilutions. In this study, PC did not induce alterations in fibroblast viability. Nitric oxide was detected in extract-treated cell supernatants and also in the extracts only, suggesting presence of nitrite in the soluble content of the tested materials. In the present study, MTA Fillapex displayed the highest cytotoxic effect on periodontal ligament fibroblasts followed by white MTA and PC.

  15. Effect of Nano-SiO₂ on the Hydration and Microstructure of Portland Cement.

    Science.gov (United States)

    Wang, Liguo; Zheng, Dapeng; Zhang, Shupeng; Cui, Hongzhi; Li, Dongxu

    2016-12-15

    This paper systematically studied the modification of cement-based materials by nano-SiO₂ particles with an average diameter of about 20 nm. In order to obtain the effect of nano-SiO₂ particles on the mechanical properties, hydration, and pore structure of cement-based materials, adding 1%, 3%, and 5% content of nano-SiO₂ in cement paste, respectively. The results showed that the reaction of nano-SiO₂ particles with Ca(OH)₂ (crystal powder) started within 1 h, and formed C-S-H gel. The reaction speed was faster after aging for three days. The mechanical properties of cement-based materials were improved with the addition of 3% nano-SiO₂, and the early strength enhancement of test pieces was obvious. Three-day compressive strength increased 33.2%, and 28-day compressive strength increased 18.5%. The exothermic peak of hydration heat of cement increased significantly after the addition of nano-SiO₂. Appearance time of the exothermic peak was advanced and the total heat release increased. Thermogravimetric-differential scanning calorimetry (TG-DSC) analysis showed that nano-SiO₂ promoted the formation of C-S-H gel. The results of mercury intrusion porosimetry (MIP) showed that the total porosity of cement paste with 3% nano-SiO₂ was reduced by 5.51% and 5.4% at three days and 28 days, respectively, compared with the pure cement paste. At the same time, the pore structure of cement paste was optimized, and much-detrimental pores and detrimental pores decreased, while less harmful pores and innocuous pores increased.

  16. Durability Index Performance of High Strength Concretes Made Based on Different Standard Portland Cements

    Directory of Open Access Journals (Sweden)

    Stephen O. Ekolu

    2012-01-01

    Full Text Available A consortium of three durability index test methods consisting of oxygen permeability, sorptivity and chloride conductivity were used to evaluate the potential influence of four (4 common SANS 10197 cements on strength and durability of concrete. Twenty four (24 concrete mixtures of water-cement ratios (w/c's = 0.4, 0.5, 0.65 were cast using the cement types CEM I 42.5N, CEM II/A-M (V-L 42.5N, CEM IV/B 32.5R and CEM II/A-V 52.5N. The concretes investigated fall in the range of normal strength, medium strength and high strength concretes. It was found that the marked differences in oxygen permeability and sorptivity results observed at normal and medium strengths tended to vanish at high concrete strengths. Also, the durability effects attributed to use of different cement types appear to diminish at high strengths. Cements of low strength and/or that contained no extenders (CEM 32.5R, CEM I 42.5N showed greater sensitivity to sorptivity, relative to other cement types. Results also show that while concrete resistance to chlorides generally improves with increase in strength, adequately high chloride resistance may not be achieved based on high strength alone, and appropriate incorporation of extenders may be necessary.

  17. Resistance to acid attack of portland cement mortars produced with red mud as a pozzolanic additive; Resistencia ao ataque acido de argamassas de cimento Portland produzido com residuo de bauxita como aditivo pozolanico

    Energy Technology Data Exchange (ETDEWEB)

    Balbino, Thiago Gabriel Ferreira; Fortes, Gustavo Mattos; Lourenco, Rafaela Roberta; Rodrigues, Jose de Anchieta [Universidade Federal de Sao Carlos (DEMa/PPGCEM/UFSCar), SP (Brazil). Programa de Pos-Graducao em Ciencia e Engenharia de Materiais. Departamento de Engenharia de Materiais; Montini, Marcelo [Alcoa Aluminio S.A., Pocos de Caldas, MG (Brazil)

    2011-07-01

    Portland cement structures are usually exposed to aggressive environments, which requires the knowledge of the performance of these materials under deleterious conditions. In this study, it was evaluated the resistance to acid attack of mortars that contain ordinary (CPI) and compost (CPII-Z) Portland cements, adding to the first red mud (RB) as a pozzolanic additive in different conditions: without calcination, calcined at 400 ° C and at 600 ° C. The specimens were subjected to HCl and H{sub 2}SO{sub 4} solutions, both with concentration of 1.0 Mol L{sup -1} for 28 days, monitoring the weight loss and leached material nature by atomic emission inductively coupled plasma (ICP). The hydration products were studied by thermogravimetric analysis (TGA) and X-ray diffraction (XRD) of the hydrated cement pastes. It was observed a reduction of portlandite amount in the RB containing cement pastes, indicating a possible pozzolanic activity of the red mud. The mortars prepared with RB were more resistant to HCl, while that ones with calcined RB present a better performance in H{sub 2}SO{sub 4} attack. (author)

  18. The microstructure of Portland cement paste and its relationship to drying shrinkage: A study of blended cement paste

    Science.gov (United States)

    Olson, Rudolph Andrew, III

    1998-12-01

    The objective was to understand how the microstructure of cement paste influences its susceptibility to drying shrinkage. The strategy was to vary the microstructure via processing and relate the changes to the deformation behavior. There were many processing parameters to choose from that were capable of varying the microstructure, but one very effective way was through addition of mineral admixtures. Since the use of mineral admixtures also has the potential to address current economic, social, and environmental problems, achieving a better understanding of blended cement paste was an added benefit. Ground granulated blast furnace slag, fly ash, and silica fume were the mineral admixtures chosen for this study because they represent a wide range of reactivity. Blended cement pastes of various compositions and degrees of hydration were characterized. Calcium hydroxide, calcium silicate hydrate, pH, free water, and nitrogen surface area were the microstructural parameters chosen for analysis. Because calcium silicate hydrate is usually measured by indirect techniques which are not applicable to blended cements, a technique based on water adsorption was developed; results compared favorably with calculations from the Jennings-Tennis hydration model. The connectivity of the pore network was characterized using impedance spectroscopy. Drying shrinkage was analyzed on the macrolevel using bulk shrinkage measurements and the microstructural level using a deformation mapping technique. Several processing-microstructure-property relationships were developed. Mineral admixtures were found to significantly reduce the connectivity of the pore network and increase the nitrogen surface area of cement paste per gram of calcium silicate hydrate. The bulk drying shrinkage of blended cement pastes dried to 50% relative humidity was found to depend primarily on calcium hydroxide and calcium silicate hydrate content; shrinkage decreased with increasing amounts of calcium hydroxide

  19. Hydration of ordinary portland cements made from raw mix containing transition element oxides

    Energy Technology Data Exchange (ETDEWEB)

    Kakali, G.; Tsivilis, S.; Tsialtas, A. [National Technical Univ. of Athens (Greece)

    1998-03-01

    The use of industrial wastes, such as waste tires, waste oil, non-ferrous metal slag, or waste molding sand, as alternative raw materials and fuel in cement plants has been established from an environmental and recycling point of view and is expected to increase in the future. Cement is broadly used, among other hydraulic binders, in the solidification and stabilization of industrial and municipal wastes. This tendency to the use of wastes in the cement industry or the utilization of cement for the handling of wastes has led to the presence of several transition element compounds in the clinker and/or in the hydrated cement. The subject of this paper is the study of the hydration process in cements made from raw mixes containing transition element oxides. The oxides used are ZrO{sub 2}, V{sub 2}O{sub 5}, Ni{sub 2}O{sub 3}, CuO, Co{sub 2}O{sub 3}, MnO, Cr{sub 2}O{sub 3}, TiO{sub 2}, MoO{sub 3}, and ZnO, and their percentage in the raw mixes is 2% w/w. The cement pastes are cured in water for 24 h, 48 h, 7 days and 28 days. Hydration rate and products are studied by means of X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. As it is concluded, the added oxides provoke, in general, a retardation of the hydration reactions. The effect is stronger during the first 2 days and becomes negligible at 28 days. The addition of CuO strongly delays the hydration even after 28 days. Its action is related to the formation of Cu(OH){sub 2} during the first days of hydration.

  20. Evolution and quantification of the main sensitisers in commercial Portland cements

    OpenAIRE

    2002-01-01

    [ES] Los cementos Portland comerciales contienen elementos minoritarios en su composición química. La presencia de estos elementos tiene una incidencia directa en diferentes aspectos: comportamiento reológico, cinética de reacción, contaminación ambiental, etc. Algunos de ellos, aparte de su incidencia mencionada anteriormente, tienen un efecto negativo en la salud humana. Así, el cromo (Cr), níquel (Ni) y cobalto (Co) son los principales alérgenos contenidos en los cementos y, po...

  1. Chloride adsorption by calcined layered double hydroxides in hardened Portland cement paste

    KAUST Repository

    Yoon, Seyoon

    2014-06-01

    This study investigated the feasibility of using calcined layered double hydroxides (CLDHs) to prevent chloride-induced deterioration in reinforced concrete. CLDHs not only adsorbed chloride ions in aqueous solution with a memory effect but also had a much higher binding capacity than the original layered double hydroxides (LDHs) in the cement matrix. We investigated this adsorption in hardened cement paste in batch cultures to determine adsorption isotherms. The measured and theoretical binding capacities (153 mg g -1 and 257 mg g-1, respectively) of the CLDHs were comparable to the theoretical capacity of Friedel\\'s salt (2 mol mol-1 or 121 mg g-1), which belongs to the LDH family among cementitious phases. We simulated chloride adsorption by CLDHs through the cement matrix using the Fickian model and compared the simulation result to the X-ray fluorescence (XRF) chlorine map. Based on our results, it is proposed that the adsorption process is governed by the chloride transport through the cement matrix; this process differs from that in an aqueous solution. X-ray diffraction (XRD) analysis showed that the CLDH rebuilds the layered structure in a cementitious environment, thereby demonstrating the feasibility of applying CLDHs to the cement and concrete industries. © 2014 Published by Elsevier B.V. All rights reserved.

  2. Preliminary Examination of the System Fly Ash-Bottom Ash-Flue Gas Desulphurization Gypsum-Portland Cement-Water for Road Construction

    Directory of Open Access Journals (Sweden)

    R. Tokalic

    2013-01-01

    Full Text Available This paper describes an investigation into the use of three power plant wastes: fly ash, flue gas desulphurization gypsum, and bottom ash for subbase layers in road construction. Two kinds of mixtures of these wastes with Portland cement and water were made: first with fly ash consisting of coarser particles (<1.651 mm and second with fly ash consisting of smaller particles (<0.42 mm. The mass ratio of fly ash-Portland cement-flue gas desulphurization gypsum-bottom ash was the same (3 : 1 : 1 : 5 in both mixtures. For both mixtures, the compressive strength, the mineralogical composition, and the leaching characteristics were determined at different times, 7 and 28 days, after preparation. The obtained results showed that both mixtures could find a potential use for subbase layers in road construction.

  3. High-volume natural volcanic pozzolan and limestone powder as partial replacements for portland cement in self-compacting and sustainable concrete

    KAUST Repository

    Celik, Kemal

    2014-01-01

    A laboratory study demonstrates that high volume, 45% by mass replacement of portland cement (OPC) with 30% finely-ground basaltic ash from Saudi Arabia (NP) and 15% limestone powder (LS) produces concrete with good workability, high 28-day compressive strength (39 MPa), excellent one year strength (57 MPa), and very high resistance to chloride penetration. Conventional OPC is produced by intergrinding 95% portland clinker and 5% gypsum, and its clinker factor (CF) thus equals 0.95. With 30% NP and 15% LS portland clinker replacement, the CF of the blended ternary PC equals 0.52 so that 48% CO2 emissions could be avoided, while enhancing strength development and durability in the resulting self-compacting concrete (SCC). Petrographic and scanning electron microscopy (SEM) investigations of the crushed NP and finely-ground NP in the concretes provide new insights into the heterogeneous fine-scale cementitious hydration products associated with basaltic ash-portland cement reactions. © 2013 Published by Elsevier Ltd.

  4. Microstructure engineering of Portland cement pastes and mortars through addition of ultrafine layer silicates

    DEFF Research Database (Denmark)

    Lindgreen, Holger; Geiker, Mette Rica; Krøyer, Hanne;

    2008-01-01

    , and the nano-structure of the C-S-H depends on type of layer silicate. The effect of layer silicate addition is most pronounced for palygorskite and smectite having the largest surface area and negative charges on the particle surfaces. The cement pastes containing palygorskite and bentonite have......, in comparison to the pure cement pasta and the paste containing kaolinite, a more open pore structure consisting of fine pores. Silica fume paste contains a significant amount of closed pores. As a secondary result, it is demonstrated that both the degree and duration of sample drying strongly modifies...

  5. A thermal comparator sensor for measuring autogenous deformation in hardening Portland cement paste

    DEFF Research Database (Denmark)

    Østergaard, Thomas; Jensen, Ole Mejlhede

    2003-01-01

    of the thermal comparator is based on thermal expansion of aluminium. A particular characteristic of the measuring system is the fixation of the thermal comparator sensor to the deforming specimen. The modular system ensures effective thermostatic control of the hydrating cement paste samples. The technique......This paper describes a simple and accurate experimental device specially developed to measure autogenous deformation in hardening cement-based materials. The measuring system consists of a so-called thermal comparator sensor and a modular thermostatically controlled system. The operating principle...

  6. Effect of sewage sludge ash (SSA on the mechanical performance and corrosion levels of reinforced Portland cement mortars

    Directory of Open Access Journals (Sweden)

    Andión, L. G.ª

    2006-06-01

    Full Text Available The article describes a study conducted to determinecorrosion in reinforcement embedded in Portland cement(PC mortars with different percentages of sewage sludgeash (SSA admixtures. The polarization resistancetechnique was used to determine the steel corrosion rate(Icorr in the test specimens. The samples were subjectedto different environmental conditions and aggressiveagents: 100% relative humidity (RH, accelerated carbonationat 70% RH and seawater immersion. Portlandcement was partially substituted for SSA in the mixes atrates of 0, 10, 20, 30 and 60% (by mass to make thedifferent mortars. The results show that where cementwas replaced by SSA at rates of up to 10% by mass,mortar corrosion performance was comparable to thebehaviour observed in SSA-free mortars (control mortar:0% SSA. Data for higher rates are also shown. From themechanical standpoint, SSA exhibited moderate pozzolanicactivity and the best performance when SSA wasadded at a rate of 10% to mixes with a water/(binder:PC + SSA (w/b ratio of 0.5.Se ha estudiado el nivel de corrosion que presentan lasarmaduras embebidas en morteros fabricados con cementoPortland (CP con diferentes porcentajes de sustitucion deceniza de lodo de depuradora (CLD. Se ha utilizado la tecnicade la Resistencia a la Polarizacion para determinar lavelocidad de corrosion del acero embebido en las muestrasestudiadas. Las muestras se han sometido a diferentes condicionesambientales y agentes agresivos: 100% de humedadrelativa (HR, carbonatacion acelerada al 70% HR einmersion en agua de mar. Para la fabricacion de los distintosmorteros, el cemento Portland ha sido parcialmente sustituidopor CLD en los siguientes porcentajes en masa: 0,10, 20, 30 y 60%. Los resultados muestran que sustitucionesde cemento por CLD de hasta el 10% en masa no alteranel comportamiento frente a la corrosion de los morterosal compararlos con los morteros libres de CLD (morteroscontrol: 0% de sustitucion de cemento por CLD. Se

  7. Evaluation of Portland cement from X-ray diffraction associated with cluster analysis; Avaliacao de cimento Portland a partir da difracao de raios X associada a analise por agrupamento

    Energy Technology Data Exchange (ETDEWEB)

    Gobbo, Luciano de Andrade, E-mail: luciano.gobbo@panalytical.com [Panalytical Brasil, Sao Paulo, SP (Brazil); Montanheiro, Tarcisio Jose, E-mail: tarcisio.montanheiro@gmail.com [Instituto Geologico, Secretaria de Estado do Meio Ambiente, Sao Paulo, SP (Brazil); Montanheiro, Filipe, E-mail: flpmontanheiro@gmail.com [Universidade Estadual Paulista (LEBAC/UNESP), Rio Claro, SP (Brazil). Departamento de Geologia Aplicada. Lab. de Estudos de Bacias; Sant' Agostino, Lilia Mascarenhas, E-mail: agostino@usp.br [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Geociencias. Departamento de Geologia Sedimentar e Ambiental

    2013-12-15

    The Brazilian cement industry produced 64 million tons of cement in 2012, with noteworthy contribution of CP-II (slag), CP-III (blast furnace) and CP-IV (pozzolanic) cements. The industrial pole comprises about 80 factories that utilize raw materials of different origins and chemical compositions that require enhanced analytical technologies to optimize production in order to gain space in the growing consumer market in Brazil. This paper assesses the sensitivity of mineralogical analysis by X-ray diffraction associated with cluster analysis to distinguish different kinds of cements with different additions. This technique can be applied, for example, in the prospection of different types of limestone (calcitic, dolomitic and siliceous) as well as in the qualification of different clinkers. The cluster analysis does not require any specific knowledge of the mineralogical composition of the diffractograms to be clustered; rather, it is based on their similarity. The materials tested for addition have different origins: fly ashes from different power stations from South Brazil and slag from different steel plants in the Southeast. Cement with different additions of limestone and white Portland cement were also used. The Rietveld method of qualitative and quantitative analysis was used for measuring the results generated by the cluster analysis technique. (author)

  8. Effect of Combined Calcium Hydroxide and Accelerated Portland Cement on Bone Formation and Soft Tissue Healing in Dog Bone Lesions

    Directory of Open Access Journals (Sweden)

    Khorshidi H

    2015-09-01

    Full Text Available Statement of Problem: Recent literatures show that accelerated Portland cement (APC and calcium hydroxide Ca (OH2 may have the potential to promote the bone regeneration. However, certain clinical studies reveal consistency of Ca (OH2, as one of the practical drawbacks of the material when used alone. To overcome such inconvenience, the combination of the Ca (OH2 with a bone replacement material could offer a convenient solution. Objectives: To evaluate the soft tissue healing and bone regeneration in the periodontal intrabony osseous defects using accelerated Portland cement (APC in combination with calcium hydroxide Ca (OH2, as a filling material. Materials and Methods: Five healthy adult mongrel dogs aged 2-3 years old (approximately 20 kg in weight with intact dentition and healthy periodontium were selected for this study. Two one-wall defects in both mesial and distal aspects of the 3rd premolars of both sides of the mandible were created. Therefore, four defects were prepared in each dog. Three defects in each dog were randomly filled with one of the following materials: APC alone, APC mixed with Ca (OH2, and Ca (OH2 alone. The fourth defect was left empty (control. Upon clinical examination of the sutured sites, the amount of dehiscence from the adjacent tooth was measured after two and eight weeks, using a periodontal probe mesiodistally. For histometric analysis, the degree of new bone formation was estimated at the end of the eighth postoperative week, by a differential point-counting method. The percentage of the defect volume occupied by new osteoid or trabecular bone was recorded. Results: Measurement of wound dehiscence during the second week revealed that all five APCs had an exposure of 1-2 mm and at the end of the study all samples showed 3-4 mm exposure across the surface of the graft material, whereas the Ca (OH2, control, and APC + Ca (OH2 groups did not show any exposure at the end of the eighth week of the study. The most

  9. Contribution to the determination of gypsum and hemihydrates content in Portland cements

    Directory of Open Access Journals (Sweden)

    Moreno Arús, Fernando

    1975-09-01

    Full Text Available Not availableLa mayoría de los técnicos de cemento, aceptan, que las anormalidades del fraguado, conocidas como "falso fraguado" en el cemento portland, se deben primordialmente a la presencia de yeso parcialmente deshidratado (S04Ca1/2H20. Si el clínker que se muele está enriquecido en cal libre, o la temperatura del molino es elevada (superior a los 110 °C o hay escasa ventilación de éste, se llega a originar una parcial deshidratación del yeso, que se mantiene durante el proceso de ensilado y que origina las anormalidades del fraguado al que anteriormente nos hemos referido. Por esta razón creemos muy importante poder conocer el grado de deshidratación en que se encuentra el yeso en un cemento.

  10. Portland cement with additives in the repair of furcation perforations in dogs Cimento Portland com aditivos na reparação de perfurações radiculares em cães

    Directory of Open Access Journals (Sweden)

    José Dias da Silva Neto

    2012-11-01

    Full Text Available PURPOSE: To evaluate the use of Portland cements with additives as furcation perforation repair materials and assess their biocompatibility. METHODS: The four maxillary and mandibular premolars of ten male mongrel dogs (1-1.5 years old, weighing 10-15 kg received endodontic treatment (n=80 teeth. The furcations were perforated with a round diamond bur (1016 HL. The perforations involved the dentin, cementum, periodontal ligament, and alveolar bone. A calcium sulfate barrier was placed into the perforated bone to prevent extrusion of obturation material into the periradicular space. The obturation materials MTA (control, white, Type II, and Type V Portland cements were randomly allocated to the teeth. Treated teeth were restored with composite resin. After 120 days, the animals were sacrificed and samples containing the teeth were collected and prepared for histological analysis. RESULTS: There were no significant differences in the amount of newly formed bone between teeth treated with the different obturation materials (p=0.879. CONCLUSION: Biomineralization occurred for all obturation materials tested, suggesting that these materials have similar biocompatibility.OBJETIVO: Avaliar o uso de cimentos Portland aditivados na reparação de perfurações radiculares e a biocompatibilidade destes materiais. MÉTODOS: Oitenta pré-molares, quatro da arcada dentária superior e quatro da arcada inferior de 10 cães machos, sem raça definida, com idade em torno de um a um ano e meio, pesando entre 10 e 15 kg foram submetidos a tratamento endodôntico, sendo realizadas perfurações nas furcas com broca de diamante 1016 HL. A cavidade envolveu dentina e cemento, como também periodonto e o osso alveolar. Na porção óssea da obturação, barreira de sulfato de cálcio foi utilizada evitando extravasamento do cimento para o espaço periodontal. Foi realizada a distribuição randomizada dos cimentos MTA (controle, Portland tipo II, Portland tipo V e

  11. Evaluation of Photocatalytic Properties of Portland Cement Blended with Titanium Oxynitride (TiO2−xNy Nanoparticles

    Directory of Open Access Journals (Sweden)

    Juan D. Cohen

    2015-07-01

    Full Text Available Photocatalytic activity of Portland cement pastes blended with nanoparticles of titanium oxynitride (TiO2−xNy was studied. Samples with different percentages of TiO2−xNy (0.0%, 0.5%, 1%, 3% and TiO2 (1%, 3% were evaluated in order to study their self-cleaning properties. The presence of nitrogen in the tetragonal structure of TiO2 was evidenced by X-ray diffraction (XRD as a shift of the peaks in the 2θ axis. The samples were prepared with a water/cement ratio of 0.5 and a concentration of Rhodamine B of 0.5 g/L. After 65 h of curing time, the samples were irradiated with UV lamps to evaluate the reduction of the pigment. The color analysis was carried out using a Spectrometer UV/Vis measuring the coordinates CIE (Commission Internationale de l’Eclairage L*, a*, b*, and with special attention to the reddish tones (Rhodamine B color which correspond to a* values greater than zero. Additionally, samples with 0.5%, 1%, 3% of TiO2−xNy and 1%, 3% of TiO2 were evaluated under visible light with the purpose of determining the Rhodamine B abatement to wavelengths greater than 400 nm. The results have shown a similar behavior for both additions under UV light irradiation, with 3% being the addition with the highest photocatalytic efficiency obtained. However, TiO2−xNy showed activity under irradiation with visible light, unlike TiO2, which can only be activated under UV light.

  12. Effect of high doses of chemical admixtures on the strength development and freeze-thaw durability of portland cement mortar

    Science.gov (United States)

    Korhonen, Charles J.

    This thesis examines the low-temperature strength development of portland cement concrete made with high doses of chemical admixtures dissolved in the mixing water and the possible beneficial effect of these admixtures on that concrete's long-term freeze-thaw durability. The literature shows that high doses of chemical admixtures can protect fresh concrete against freezing and that, under certain conditions, these admixtures can enhance the freeze-thaw durability of concrete. The challenge is that there are no acceptance standards in the U.S. that allow chemicals to be used to protect concrete against freezing. Also, the perception is that chemicals might somehow harm the concrete. This perception seems to be based on the fact that deicing salts, when applied to concrete pavement, cause roadways to scale away. This study investigated the effect of high doses of commercially available admixtures on fresh concrete while it gained strength at low temperature and on hardened concrete exposed to repeated cycles of freezing and thawing in a moist environment. The reason for studying off-the-shelf admixtures was that these materials are approved for use in concrete; they were already governed by their own set of standards. Four mortars were examined, each with a different cement and water content, when dosed with five commercial admixtures. This allowed the fresh mortar to gain appreciable strength when it was kept at nearly -10C. The admixtures also enhanced the freeze-thaw durability of the mortar, even when it was not air-entrained. Clearly, as the dosage of admixture increased beyond approximately 22% by weight of water, the mortar appeared to be unaffected by up to 700 cycles of freezing and thawing.

  13. Radon resistant potential of concrete manufactured using Ordinary Portland Cement blended with rice husk ash

    Science.gov (United States)

    Chauhan, R. P.; Kumar, Amit

    2013-12-01

    The emission of radon from building materials and soil depends upon the radium content, porosity, moisture content and radon diffusion length of materials. Several techniques have been used to reduce the radon emission from the soil using different flooring materials. But the effectiveness of radon shielding depends upon the diffusion of radon through these materials. The present study proposes a method for producing a radon resistant material for decreasing radon diffusion through it. The method involves rice husk ash (RHA) in addition to cement for the preparation of concrete used for flooring and walls. The radon diffusion, exhalation and mechanical property of concrete prepared by rice husk ash blended cement were studied. The addition of RHA caused the reduction in radon diffusion coefficient, exhalation rates, porosity and enhanced the compressive strength of concrete. The bulk radon diffusion coefficient of cementitious concrete was reduced upto 69% by addition of rice husk ash as compare to that of control concrete.

  14. CERAMIC WASTES AS RAW MATERIALS IN PORTLAND CEMENT CLINKER FABRICATION.· CHARACTERIZATION AND ALKALINE ACTIVATION

    OpenAIRE

    2006-01-01

    [EN] The world-wide cementindustry is seeking experimentalavenues that wi// lead to cementproduction that is less energy-intensive/ less damaging to the surrounding environment and less prolific in GHGemissions. In Spain andEurope in general, this approach is who//y consistent with the concept of sustainability and compliance with the Kyoto Protocol. The use ofdifferent kinds of industrial waste and by-products as alternative materials in cement manufacture has proved to ...

  15. Characterization of sugar cane bagasse ash as supplementary material for Portland cement

    OpenAIRE

    Janneth Torres Agredo; Ruby Mejía de Gutiérrez; Escandón Giraldo, Camilo E.; Luis Octavio González Salcedo

    2014-01-01

    Sugar Cane Bagasse is a by-product of the sugar agroindustry; it is partly used as fuel. However, bagasse ash (SCBA) is considered waste, which creates a disposal problem. Furthermore, if sugar cane bagasse is burned under controlled conditions, the SCBA can be potentially reused. This paper considers the technical viability of using SCBA as a partial replacement for cement. Two samples of SCBA from a Colombian sugar industry were characterized. The chemical composition of the samples shows h...

  16. Studies on the behaviour of different spent fluidized-bed catalytic cracking catalysts on Portland cement

    OpenAIRE

    J. PAYÁ; Borrachero, M. V.; Monzó, J.; Soriano, L.

    2009-01-01

    The fluidized-bed catalytic cracking catalyst (FCC) it is a residue from the industry of the petroleum that shows a high pozzolanic reactivity and, in cementing matrix, it significantly improves their mechanical behaviour as well as durability. In this research a comparative study on residues of catalyst from different sources has been carried out, in order to know if these residues can be used jointly in an indiscriminate way or, on the contrary, it is necessary to classify them according to...

  17. Effect of various Portland cement paste compositions on early-age strain

    Science.gov (United States)

    Guzzetta, Alana G.

    Early-age strain in paste, mortar, and concrete mixtures was investigated using a new method where the specimen shape was a cone frustum. Strain of the specimen from both the horizontal and vertical directions was captured by height change measurement. The volumetric strain was then calculated as a function of the height change and was plotted versus time. A correlation was found between the slopes of the volumetric strain curve resulting from this test method and the initial setting time of the tested material. An initial evaluation of the repeatability of this innovative test method was conducted. The early-age strain effects of aggregate volume, shrinkage reducing admixture, water-cementitious ratio (w/cm), and partial cement replacement with supplementary cementitious materials were tested and individually compared. From these comparisons, it was observed that ambient temperature, bleed water development, and rheological properties had a significant impact on the volumetric strain results. Data showed increased strain as aggregate volume was reduced and as the w/cm was changed from 0.25 up to 0.50. The addition of shrinkage reducing admixture generally caused an increase in the 36-hour volumetric strain value. In most of the mixtures, cement replacement with 20% fly ash or 10% metakaolin reduced the measured volumetric strain when the w/cm was 0.30. Replacement of cement with 10% silica fume caused an insignificant change in volumetric strain results.

  18. Characterization of sugar cane bagasse ash as supplementary material for Portland cement

    Directory of Open Access Journals (Sweden)

    Janneth Torres Agredo

    2014-03-01

    Full Text Available Sugar Cane Bagasse is a by-product of the sugar agroindustry; it is partly used as fuel. However, bagasse ash (SCBA is considered waste, which creates a disposal problem. Furthermore, if sugar cane bagasse is burned under controlled conditions, the SCBA can be potentially reused. This paper considers the technical viability of using SCBA as a partial replacement for cement. Two samples of SCBA from a Colombian sugar industry were characterized. The chemical composition of the samples shows high percentages of silica, 76.3% and 63.2%. The mineralogical and morphological characteristics of the waste were determined by X-ray diffraction patterns (XRD, thermal analysis (TG/DTA and scanning electron microscopy (SEM. The pozzolanic activity of SCBA was evaluated using the Frattini test and the strength activity index test (SAI. The ASTM C618 defines an SAI of at least 75% as a requirement for classifying material as a pozzolan. This condition was achieved in the experiments performed. The results indicate that SCBA produced in the manufacture of commercial cements can be recycled for use as pozzolanic material. This supplementary material can partially replace cement and therefore reduce CO2 emissions.

  19. A comparative evaluation of ProRoot mineral trioxide aggregate and Portland cement as a pulpotomy medicament

    Directory of Open Access Journals (Sweden)

    Dipti Bhagat

    2016-01-01

    Full Text Available Introduction: Recently, some studies have compared mineral trioxide aggregate (MTA with portland cement (PC, concluding that the principle ingredients of PC are similar to those of MTA. The purpose of the present study was to evaluate the biocompatibility of PC as a pulpotomy medicament. Materials and Methods: Thirty premolars that scheduled for extraction for therapeutic reasons were randomly assigned to two experimental groups: ProRoot MTA (PMTA and PC. After isolation and pulp exposure, pulpotomy was carried out and pulps were dressed with PMTA and PC. After 6 months, the teeth were extracted and prepared for histological analysis based on Cox et al. criteria. The data were analyzed by Z-test of proportion with 1% of allowed error. Results: No statistically significant difference was found between the two groups with respect to inflammatory response, soft tissue organization, and dentine bridge formation (P > 0.05. Conclusions: PC was associated with similar favorable biological response to pulpotomy treatment as PMTA. The findings of this study support the idea that PC can be considered a cheaper substitute to MTA.

  20. An investigation on the use of tincal ore waste, fly ash, and coal bottom ash as Portland cement replacement materials

    Energy Technology Data Exchange (ETDEWEB)

    Kula, I.; Olgun, A.; Sevinc, V.; Erdogan, Y. [Dumlupinar University, Kutahya (Turkey). Dept. of Chemistry

    2002-02-01

    The possibility of using tincal ore waste (TW), coal bottom ash (BA), and fly ash (FA) as partial replacement in concrete was examined through a number of tests. The properties examined include setting time, compressive strength, mortar expansion, water consistency of mortar, and microstructure. The results showed that compressive strength of all specimens containing 1 wt.% of TW was higher than that of the control at the 28th day of curing. At 90 days, the contribution to strength by BA + TW and FA + TW was higher than in the concrete-prepared equivalent TW beyond 3 wt.% of Portland cement (PC) replacement. With the replacement of 3-5 wt.% of PC by TW, the compressive strength of the concrete decreased compared to control concrete. However, the values obtained are within the limit of Turkish Standards. Adding BA or FA with TW improved the performance relative to TW replacement only. Increasing replacement of TW gives rise to a higher setting time. As a result. TW, BA, and FA samples may be used as cementitious materials.

  1. Effect of Nanosilica on the Fresh Properties of Cement-Based Grouting Material in the Portland-Sulphoaluminate Composite System

    Directory of Open Access Journals (Sweden)

    Shengli Li

    2016-01-01

    Full Text Available The effect of NS particle size and content on the fresh properties of the grouting material based on the portland-sulphoaluminate composite system was analyzed. The experimental results indicated that air content increased and apparent density decreased, with increased NS content, but the NS particle sizes have minimal effect on the air content and apparent density. The setting time of mortar was significantly shortened, with increased NS content; however, NS particle sizes had little influence on the setting time. The effect of fluidity on the mortars adding NS with particle size of 30 nm is larger than NS with particle sizes of 15 and 50 nm and the fluidity decreased with increased NS content, but the fluidity of mortars with the particle sizes of 15 and 50 nm is almost not affected by the NS content. XRD analysis shows that the formation of ettringite was promoted and the process of hydration reaction of cement was accelerated with the addition of NS. At the microscopic level, the interfacial transition zone (ITZ of the grouting material became denser and the formation of C-S-H gel was promoted after adding NS.

  2. Comparison of the sealing ability of mineral trioxide aggregate and Portland cement used as root-end filling materials.

    Science.gov (United States)

    Shahi, Shahriar; Yavari, Hamid R; Rahimi, Saeed; Eskandarinezhad, Mahsa; Shakouei, Sahar; Unchi, Mahsa

    2011-12-01

    Inadequate apical seal is the major cause of surgical endodontic failure. The root-end filling material used should prevent egress of potential contaminants into periapical tissue. The purpose of this study was to compare the sealing ability of four root-end filling materials: white mineral trioxide aggregate (MTA), gray MTA, white Portland cement (PC) and gray PC by dye leakage test. Ninety-six human single-rooted teeth were instrumented, and obturated with gutta-percha. After resecting the apex, an apical cavity was prepared. The teeth were randomly divided into four experimental groups (A: white MTA, B: gray MTA, C: white PC and D: gray PC; n = 20) and two control groups (positive and negative control groups; n = 8). Root-end cavities in the experimental groups were filled with the experimental materials. The teeth were exposed to Indian ink for 72 hours. The extent of dye penetration was measured with a stereomicroscope at 16× magnification. The negative controls showed no dye penetration and dye penetration was seen in the entire root-end cavity of positive controls. However, there was no statistically significant difference among the four experimental groups (P > 0.05). All retrograde filling materials tested in this study showed the same microleakage in vitro. Given the low cost and apparently similar sealing ability of PC, PC could be considered as a substitute for MTA as a root-end filling material.

  3. 砒砂岩对硅酸盐和硫铝酸盐水泥性能的影响%Impact of feldspathic stone on performance of Portland cement and sulphoaluminate cement

    Institute of Scientific and Technical Information of China (English)

    张云; 汪自庆; 何欢; 张雪冰; 申卫博

    2016-01-01

    The one-single and multi-level gradient test were selected to investigate the influence of feldspathic stone on the physical properties of Portland cement and sulphoaluminate cement,with the comparison of different feldspathic stone substitution,setting time,standard consistency water consumption and mechanical performance of Portland cement and sulphoaluminate cement were tested.The results show that the certain amount of feldspathic stone shortens the setting time of Portland cement and sulphoaluminate cement.The initial setting time of Portland cement and sulphoaluminate cement are shortened by 30% and 47%,and the water requirement for normal consistency of Portland cement and sulphoaluminate cement are increased by 6.6% and 21.7%,separately,when the substitution of feldspathic stone powders is 5%.Mechanical performance of Portland cement is positive with 10% mass fraction substitution of feldspathic stone,and the compressive strength of 3 d and 28 d are increased by 7.2% and 6%,respectively.The compressive strength of sulphoaluminate cement is decreased with the increasing of feldspathic stone.%为了研究砒砂岩对硅酸盐水泥和硫铝酸盐水泥物理性能的影响,采用单因素多水平梯度实验,通过不同砒砂岩掺量的对比,测定硅酸盐水泥和硫铝酸盐水泥的凝结时间、标准稠度用水量和胶砂强度等性能.结果表明:砒砂岩对硅酸盐水泥和硫铝酸盐水泥皆有促凝作用,当砒砂岩掺量质量分数为5%时硅酸盐水泥的初凝时间会缩短30%,硫铝酸盐水泥初凝时间缩短47%,硅酸盐水泥和硫铝酸盐水泥的标准稠度用水量分别增加6.6%和21.7%;砒砂岩掺量质量分数为10%时,硅酸盐水泥的3d和28 d的强度分别增加7.2%和6%,对其力学性能有较大影响;掺入砒砂岩后,硫铝酸盐水泥强度降低,且随掺量增加,抗压强度降幅增大.

  4. Evaluation of the Apical Sealability of Mineral Trioxide Aggregate and Portland Cement as Root Canal Filling Cements: An in Vitro Study

    Directory of Open Access Journals (Sweden)

    M.S. Rekab

    2010-12-01

    Full Text Available Objective: One of the principle purposes of root canal obturation is to obtain hermetic sealing of the root canal system. According to the development of technology, many materials are now used in root canal filling. An in vitro dye leakage study was performed toevaluate the apical sealability of White-colored Mineral Trioxide Aggregate (WMTA and Gray-colored Portland Cement (GPC when used alone or as a sealer with gutta-percha points in root canal filling.Materials and Methods: Seventy-five single-rooted extracted human teeth were used in this study. After cleaning and shaping, the teeth were randomly divided into five equal groups of 15 teeth each based on the root canal filling material used; Group 1, (WMTAalone; Group 2, (GPC alone; Group 3, (Gutta-percha points + WMTA; Group 4,(Guttapercha points + GPC; Group 5, (Gutta-percha points + AH26. Methylene blue was used to determine the apical leakage. After sectioning the teeth longitudinally, linear dye penetrationwas measured with a caliper under the stereomicroscope. Data were analyzed by Kruskal-Wallis and one-way ANOVA tests with (P 0.05 as the level of significance.Results: The results showed that there were no statistically significant differences among the materials of five groups.Conclusion: (WMTA alone, (Gutta-percha points + WMTA, (GPC alone and (Guttapercha points + GPC may be used in the root canal filling.

  5. Freeze-Thaw Performance and Moisture-Induced Damage Resistance of Base Course Stabilized with Slow Setting Bitumen Emulsion-Portland Cement Additives

    Directory of Open Access Journals (Sweden)

    Mojtaba Shojaei Baghini

    2015-01-01

    Full Text Available Freeze-thaw (FT cycles and moisture susceptibility are important factors influencing the geotechnical characteristics of soil-aggregates. Given the lack of published information on the behavior of cement-bitumen emulsion-treated base (CBETB under environmental conditions, especially freezing and thawing, this study investigated the effects of these additives on the CBETB performance. The primary goal was to evaluate the resistance of CBETB to moisture damage by performing FT, Marshall conditioning, and AASHTO T-283 tests and to evaluate the long-term stripping susceptibility of CBETB while also predicting the liquid antistripping additives to assess the mixture’s durability and workability. Specimens were stabilized with Portland cement (0%–6%, bitumen emulsion (0%–5%, and Portland cement-bitumen emulsion mixtures and cured for 7 days, and their short- and long-term performances were studied. Evaluation results of both the Marshall stability ratio and the tensile strength ratio show that the additions of additives increase the resistance of the mixtures to moisture damage. Results of durability tests performed for determining the resistance of compacted specimens to repeated FT cycles indicate that the specimen with the 4% cement-3% bitumen emulsion mixture significantly improves water absorption, volume changes, and weight losses. This indicates the effectiveness of this additive as a road base stabilizer with excellent engineering properties for cold regions.

  6. Effect of poly car boxy late admixtures on portland cement paste setting and rheological behaviour

    Directory of Open Access Journals (Sweden)

    Puertas, F.

    2005-03-01

    Full Text Available The objective of the work was to determine the effects of polycarboxilated-type admixture on the setting times and the rheological properties of different types of cements including CEM I 42.5 R, CEM Il/B-V 42.5 N and CEM III/B 32.5 N, defined according to the UNE EN 197-1:2000 standard. The results show that there is a lineal relationship between the initial setting times and the admixture dosage. Mathematical equations that model this behaviour for each of the cements have been determined. The data obtained from the minislump test and from the rheological parameters determined using the rheometer (plastic viscosity and yield stress point to similar conclusions. It was also verified that the workability effect of the polycarboxilate admixture is most intense for blended cements.

    El objetivo de este trabajo ha sido estudiar el efecto de la dosificación de un aditivo basado en policarboxilatos sobre el inicio de tiempo de fraguado y las propiedades reo lógicas en pastas de diferentes tipos de cemento (CEM 142.5 R, CEM 11/ B-V42.5 NYCEMIII/B 32.5 N-Norma EN 197-1:2000. existe una relación lineal entre el inicio del fraguado y la dosificación del aditivo, se han determinado las ecuaciones matemáticas que describen este comportamiento para cada cemento, los resultados obtenidos sobre la fluidez de la pasta en el ensayo del "minislump" coinciden con la evolución de los valores de los parámetros reológicos (esfuerzo de cizalladura y viscosidad plástica determinados a través de un reómetro. el efecto fluidificante del aditivo superplastificante basado en policarboxilatos es mucho más marcado en cementos que contienen adiciones.

  7. SUGARCANE BAGASSE ASH AS A PARTIAL-PORTLAND-CEMENT-REPLACEMENT MATERIAL

    Directory of Open Access Journals (Sweden)

    MARCOS OLIVEIRA DE PAULA

    2010-01-01

    Full Text Available Esta investigación se centra en la evaluación de los efectos de la sustitución parcial del cemento Portland por cenizas de bagazo de caña de azúcar (CBC en morteros. El objetivo principal fue encontrar un uso adecuado para este residuo agrícola que es generado en una cantidad cada vez mayor en Brasil, ya que el uso de CBC como un mineral mezclado en morteros y concretos, contribuye a disminuir el impacto ambiental de estos materiales relacionados con la producción de cemento. Técnicas experimentales fueron aplicadas tanto para la caracterización del CBC, como para la evaluación de su uso como una mezcla de minerales en los morteros, basados en pruebas físicas y mecánicas. Los resultados de las pruebas con morteros indicaron la viabilidad de la sustitución parcial del cemento por CBC, hasta en un 20%.

  8. Biofouling e biodeterioração química de argamassa de cimento portland em reservatório de usina hidroelétrica Biofouling and chemical biodeterioration in hydroeletric power plant portland cement mortar

    Directory of Open Access Journals (Sweden)

    Kleber Franke Portella

    2009-01-01

    Full Text Available Last decade Brazilian rivers experimented progressive biofouling of Limnoperna fortunei communities and Cordylophora caspia hydroids. The microhabitat is so favorable that in around 1.5 years L. fortunei increased from 0.39 to nearby 149,000 units/m². Ten Portland cement mortar samples were produced with 1: 3.5: 0.4 dosages and installed for 1 year at Salto Caxias Brazilian Power Plant reservoir in 0.5 m and 1.0 m deep to investigate the biofouling influence on hydraulic civil structures. SEM, EDS, visual investigation and XRF results indicate none direct chemical interrelationships between L. fortunei and the mortar samples. However C. caspia diminished the mortar surface resistance and caused cement paste leaching.

  9. Compressive Strength of Volcanic Ash/Ordinary Portland Cement Laterized Concrete

    Directory of Open Access Journals (Sweden)

    Olusola K. O.

    2010-01-01

    Full Text Available This study investigates the effect of partial replacement of cement with volcanic ash (VA on the compressive strength of laterized concrete. A total of 192 cubes of 150mm dimensions were cast and cured in water for 7, 14, 21, and 28 days of hydration with cement replacement by VA and sand replacement by laterite both ranging from 0 to 30% respectively, while a control mix of 28-day target strength of 25 N/mm2 was adopted. The results show that the density and compressive strength of concrete decreased with increase in volcanic ash content. The 28-day, density dropped from 2390 kg/m3 to 2285 kg/m3 (i.e. 4.4% loss and the compressive strength from 25.08 N/mm2 to 17.98 N/mm2 (i.e. 28% loss for 0-30% variation of VA content with no laterite introduced. The compressive strength also decreased with increase in laterite content; the strength of the laterized concrete however increases as the curing age progresses.

  10. Influence of the Aggregate Volume on the Eleetrieal Resistivity and Properties of Portland Cement Concretes

    Institute of Scientific and Technical Information of China (English)

    WEI Xiaosheng; XIAO Lianzhen

    2011-01-01

    The electrical resistivity of concretes with various aggregate volume fractions (Va) of 0%-70%at water/cement (W/C) ratios of 0.4 and 0.5 during l day was monitored.It is found that the addition of normal aggregate to cement paste leads to a regular increase in concrete resistivity at each hydration stage and the electrical resistivity has a deeper increase for the lower W/C at a fixed aggregate volume fraction.The number of normalized resistivity (NR) of concrete to its paste matrix was introduced,which is only a function of aggregate volume fraction (Va).The quantitative relationships give an alternative method for the prediction of aggregate volume in the concrete.A logarithmic relation is established between the elastic modulus of concrete at 7 days or 28 days and the electrical resistivity of concrete at 1 day.The equations are obtained,the compressive strength of concrete at 7 days or 28 days can be determined by the electrical resistivity of concrete at 1 day and the used aggregate content in the concrete.The quantitative relationships give a non-destructive test (NDT) method for prediction of concrete elastic modulus and compressive strength.

  11. Evaluating portland cement concrete degradation by sulphate exposure through artificial neural networks modeling

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Douglas Nunes de; Bourguignon, Lucas Gabriel Garcia; Tolentino, Evandro, E-mail: tolentino@timoteo.cefetmg.br [Centro Federal de Educacao Tecnologica de Minas Gerais (CEFET-MG), Timoteo, MG (Brazil); Costa, Rodrigo Moyses, E-mail: rodrigo@moyses.com.br [Universidade de Itauna, Itauna, MG (Brazil); Tello, Cledola Cassia Oliveira de, E-mail: tellocc@cdtn.br [Centro de Desenvolvimento da Tecnologia Nucelar (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    A concrete is durable if it has accomplished the desired service life in the environment in which it is exposed. The durability of concrete materials can be limited as a result of adverse performance of its cement-paste matrix or aggregate constituents under either chemical or physical attack. Among other aggressive chemical exposures, the sulphate attack is an important concern. Water, soils and gases, which contain sulphate, represent a potential threat to the durability of concrete structures. Sulphate attack in concrete leads to the conversion of the hydration products of cement to ettringite, gypsum, and other phases, and also it leads to the destabilization of the primary strength generating calcium silicate hydrate (C-S-H) gel. The formation of ettringite and gypsum is common in cementitious systems exposed to most types of sulphate solutions. The present work presents the application of the neural networks for estimating deterioration of various concrete mixtures due to exposure to sulphate solutions. A neural networks model was constructed, trained and tested using the available database. In general, artificial neural networks could be successfully used in function approximation problems in order to approach the data generation function. Once data generation function is known, artificial neural network structure is tested using data not presented to the network during training. This paper is intent to provide the technical requirements related to the production of a durable concrete to be used in the structures of the Brazilian near-surface repository of radioactive wastes. (author)

  12. Microstructure and its relationship to fracture in portland cement mortar and concrete

    Science.gov (United States)

    Abell, Anne Bernadine

    This research explores the relationship between the geometry of crack propagation and mechanical properties of mortar and concrete. The crack deflection and branching are measured using several microscopy techniques along with image analysis of crack profiles intruded by a low melting-point alloy. The toughness measured by mechanical testing, the fracture surface geometry, phases and elastic properties identified by image analysis and microscopy, along with the crack branching relationships are used to predict the increase in the toughness of these materials with respect to the flat-crack toughness using a micromechanical model. The effect of the model parameters, microscopy techniques, material elastic properties, void modeling and branching ratio were investigated. The parametric analysis and modeling conditions determine a nearly uniform flat-crack toughness for the cement matrix of the mortar samples and a higher flat-wrack toughness for the cement matrix of the concrete samples. The trend toward a single toughness value may be an indication that there is a single material parameter to describe the fracture energy of these materials.

  13. Corrosion inhibitors for mild steel; stannous tin (SnII) in ordinary portland cement

    Energy Technology Data Exchange (ETDEWEB)

    Sagoe-Crentsil, K.K.; Glasser, F.P.; Yilmaz, V.T. (Univ. of Aberdeen (United Kingdom). Dept. of Chemistry)

    1994-01-01

    Salts containing divalent tin (SnII) are shown to give a measure of corrosion protection to mild steel embedded in cement paste. Results of linear polarization measurements are shown for samples cured at 40[degree] for up to 240 days in pastes containing initially 0-1628mM/l chloride: Sn[sup 2+], but not Sn[sup 4+], is an effective inhibitor at an initial concentration of 200mM/l. However tin solubility in pore fluid is very low: less than 0.01mM/l at 60d. It is speculated that tin stabilizes the passivating layers although no direct evidence for the incorporation of tin in corrosion product was found by analytical electron microscopy. Other theories of inhibition are discussed.

  14. Hyperbolic Method to Analyze the Electrical Resistivity Curve of Portland Cements with Superplasticizer

    Institute of Scientific and Technical Information of China (English)

    WEI Xiaosheng; XIAO Lianzhen; LI Zongjin

    2008-01-01

    Electrical measurement was employed to investigate the early hydration characteristics of cement pastes with different dosages of superplasticizer in the same W/C ratio. The hyperbolic method was applied to analyze the electrical resistivity development. The peak point (Ph) on the hyperbolic curve could be easily read. The time (th) to reach the point Ph had strong relations with the setting time. th was delayed with the increment of the dosage of superplasticizer. The time th was used to plot the relationship between the initial setting time and final setting time. The hyperbolic equation was established to predict the ultimate resistivity.The retardation effect of the superplasticizer was confirmed in the same W/C ratio by setting time and isothermal heat eyolution.

  15. Influence of CO2 Laser Radiation on the Mechanical Properties of Portland Cement Pastes

    Directory of Open Access Journals (Sweden)

    González-Mota, R.

    2011-03-01

    Full Text Available This article presents the results of the treatment of fresh cement pastes with CO2 laser radiation (10.6μm, in order to improve its mechanical properties in addition to obtaining lower setting times than those of a natural setting (without radiation . It was observed that the CO2 laser radiation has a positive influence on the mechanical properties of cement paste, not due to the heat produced during irradiation, but due to the effect of electric field propagation on water molecules, whose are arranged around functional groups of the binder and by the effect of ration, causes a micro vibration effect, resulting in a more compact and less porous paste which has better mechanical properties compared to natural setting paste. The internal and surface temperature of the samples, the evolution of setting, Young's modulus (using ultrasonic pulse velocity and compressive strength were registered.En este artículo se presentan los resultados correspondientes al tratamiento de pastas frescas de cemento con radiación láser de CO2 (10.6µm, con el propósito de mejorar sus propiedades mecánicas además de obtener tiempos de fraguado menores a los del fraguado en forma natural (sin radiación. Se demostró que la radiación con láser de CO2 influye positivamente en las propiedades mecánicas de la pasta de cemento, no por el calentamiento producido durante la irradiación, sino por el efecto de la propagación del campo eléctrico sobre las moléculas de agua que están dispuestas alrededor de los grupos funcionales del aglutinante y que al rotar producen un efecto equivalente a micro vibraciones, dando como resultado un material más compacto, con menos poros y mejores propiedades mecánicas respecto al fraguado natural. Se registró la temperatura interna y superficial de las muestras, la evolución del fraguado, el módulo de Young y la resistencia a compresión.

  16. Impact of the associated cation on chloride binding of Portland cement paste

    Energy Technology Data Exchange (ETDEWEB)

    De Weerdt, K., E-mail: klaartje.d.weerdt@ntnu.no [Department of Structural Engineering, Norwegian University of Science and Technology (Norway); Department of Engineering and Applied Sciences, University of Bergamo (Italy); Colombo, A. [Department of Structural Engineering, Norwegian University of Science and Technology (Norway); Department of Engineering and Applied Sciences, University of Bergamo (Italy); Coppola, L. [Department of Engineering and Applied Sciences, University of Bergamo (Italy); Justnes, H. [SINTEF Building and Infrastructure, Trondheim (Norway); Geiker, M.R. [Department of Structural Engineering, Norwegian University of Science and Technology (Norway)

    2015-02-15

    Well hydrated cement paste was exposed to MgCl{sub 2}, CaCl{sub 2} and NaCl solutions at 20 °C. The chloride binding isotherms for free chloride concentrations ranging up to 1.5 mol/l were determined experimentally. More chlorides were found to be bound when the associated cation was Mg{sup 2} {sup +} or Ca{sup 2} {sup +} compared to Na{sup +}. The chloride binding capacity of the paste appeared to be related to the pH of the exposure solution. In order to explain the cation dependency of the chloride binding a selection of samples was investigated in detail using experimental techniques such as TG, XRD and SEM–EDS to identify the phases binding the chlorides. The experimentally obtained data were compared with the calculations of a thermodynamic model, GEMS. It was concluded that the measured change in chloride binding depending on the cation was mainly governed by the pH of the exposure solution and thereby the binding capacity of the C-S-H.

  17. Potential use of natural red mud as pozzolan for Portland cement

    Directory of Open Access Journals (Sweden)

    Daniel Véras Ribeiro

    2011-03-01

    Full Text Available Red mud, the main waste generated in aluminum and alumina production by the Bayer process, is considered hazardous due to its high pH, according to the Brazilian standard NBR 10004/2004, and worldwide generation of this waste exceeds 117 million tons/year. In this work, non-calcined red mud was used, thus requiring less energy and time and reducing costs, which is the ideal condition for reusing wastes. Mortars containing 30 wt. (% of cement substituted by red mud showed higher strength of hardened products. The pozzolanic activity index was evaluated based on physical and mechanical parameters (Brazilian NBR 5751 and NBR 5752 standards and on a chemical analysis (European EN 196-5 standard. A comparison of the reference mixture (without red mud and the results obtained with red mud confirm the potential of non-calcined red mud for use a as pozzolanic additive in cementitious materials. The setting time (according to the MERCOSUL NM 65 standard tends to increase but workability remains almost unchanged.

  18. Studies on the behaviour of different spent fluidized-bed catalytic cracking catalysts on Portland cement

    Directory of Open Access Journals (Sweden)

    Soriano, L.

    2009-12-01

    Full Text Available The fluidized-bed catalytic cracking catalyst (FCC it is a residue from the industry of the petroleum that shows a high pozzolanic reactivity and, in cementing matrix, it significantly improves their mechanical behaviour as well as durability. In this research a comparative study on residues of catalyst from different sources has been carried out, in order to know if these residues can be used jointly in an indiscriminate way or, on the contrary, it is necessary to classify them according to their characteristics. Thus, a study on five different FCC residues, supplied from different companies, has been carried out, and their physical-chemical characteristics, pozzolanic reactivity by means of thermogravimetric analysis and the evolution of the mechanical strength of mortars were studied. After analyzing all the aspects, it can be concluded that no significant differences among the different tested catalysts were found.El catalizador de craqueo catalítico (FCC es un residuo de la industria del petróleo que posee una elevada reactividad puzolánica y en matrices cementicias mejora de manera importante los aspectos mecánicos así como de durabilidad. En este trabajo se realiza un estudio comparativo sobre residuos de catalizador de distintos orígenes, para poder conocer si se pueden utilizar conjuntamente de forma indiscriminada o por el contrario hay que catalogarlos según su origen. Para ello, se realizó un estudio sobre cinco residuos de catalizador de craqueo catalítico distintos, suministrados por diferentes empresas y se estudiaron sus características fisicoquímicas, reactividad puzolánica a través de estudios termogravimétricos y la evolución de las resistencias mecánicas en morteros. Tras analizar todos los aspectos se concluye que no existen diferencias significativas entre los distintos catalizadores empleados.

  19. Evaluation of bacterial leakage of four root- end filling materials: Gray Pro Root MTA, White Pro Root MTA, Root MTA and Portland Cement (type I

    Directory of Open Access Journals (Sweden)

    Zarabian M.

    2005-07-01

    Full Text Available Background and Aim: Today several materials have been used for root- end filling in endodontic surgery. Optimal properties of Pro Root MTA in in-vitro and in-vivo studies has been proven. On the other hand, based on some studies, Root MTA (Iranian Pro Root MTA and Portland cement are similar to Pro Root MTA in physical and biologic properties. The aim of this study was to evaluate bacterial leakage (amount and mean leakage time of four root- end filling materials. Materials and Methods: In this experimental in-vitro study, seventy six extracted single- rooted human teeth were randomly divided into six groups for root-end filling with gray Pro Root MTA, white Pro Root MTA, Root MTA (Iranian Pro Root MTA, Portland Cement (type I and positive and negative control groups. Root canals were instrumented using the step- back technique. Root- end filling materials were placed in 3mm ultra sonic retro preparations. Samples and microleakage model system were sterilized in autoclave. The apical 3-4 mm of the roots were immersed in phenol red with 3% lactose broth culture medium. The coronal access of each specimen was inoculated every 24h with a suspension of Streptococcus sanguis (ATCC 10556. Culture media were observed every 24h for colour change indicating bacterial contamination for 60 days. Statistical analysis was performed using log- rank test with P<0.05 as the limit of significance. Results: At the end of study 50%, 56.25%, 56.25% and 50% of specimens filled with Gray Pro Root MTA, White Pro Root MTA. Root MTA and Portland Cement (type I had evidence of leakage respectively. The mean leakage time was 37.19±6.29, 36.44±5.81, 37.69±5.97 and 34.81±6.67 days respectively. Statistical analysis of data showed no significant difference among the leakage (amount and mean leakage time of the four tested root- end filling materials (P=0.9958. Conclusion: Based on the results of this study, there were no significant differences in leakage among the four

  20. Influence of chloride in mortar made of Portland cement types II, III, and V on the near-field microwave reflection properties

    Science.gov (United States)

    Hu, Cairong; Benally, Aaron D.; Case, Tobias; Zoughi, Reza; Kurtis, Kimberly

    2000-07-01

    Corrosion of steel rebar in reinforced concrete structures, can be induced by the presence of chloride in the structure. Corrosion of steel rebar is a problematic issue in the construction industry as it compromises the strength and integrity of the structure. Although techniques exist for chloride detection and its migration into a structure, they are destructive, time consuming and cannot be used for the interrogation of large surfaces. In this investigation three different portland cement types; namely, ASTM types II, III and V were used, and six cubic (8' X 8' X 8') mortar specimens were produced all with water-to-cement (w/c) ratio of 0.6 and sand-to-cement (s/c) ratio of 1.5. Tap water was used when producing three of these specimens (one of each cement type). For the other three specimens calcium chloride was added to the mixing tap water resulting in a salinity of 2.5%. These specimens were placed in a hydration room for one day and thereafter left it the room temperature with low humidity. The reflection properties of these specimens, using an open-ended rectangular waveguide probe, were monitored daily at 3 GHz (S-band) and 10 GHz (X-band). The results show the influence of cement type on the reflection coefficient as well as the influence of chloride on the curing process and setting time.

  1. 77 FR 5573 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-Portland Cement...

    Science.gov (United States)

    2012-02-03

    ... Cement Association Notice is hereby given that, on January 6, 2012, pursuant to Section 6(a) of the... Cement Association (``PCA'') has filed written notifications simultaneously with the Attorney General and... this venture. Also, Texas-Lehigh Cement Company, Buda, TX; Arizona Cement Association, Phoenix,...

  2. 76 FR 12370 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-Portland Cement...

    Science.gov (United States)

    2011-03-07

    ... Cement Association Notice is hereby given that, on February 02, 2011, pursuant to Section 6(a) of the... Cement Association (``PCA'') has filed written notifications simultaneously with the Attorney General and..., PA; Lehigh Cement Company LLC, Allentown, PA; Lehigh Northwest Cement Company, Seattle, WA;...

  3. Study on Slag Powder in White Portland Cement%矿渣微粉在白色硅酸盐水泥中的应用研究

    Institute of Scientific and Technical Information of China (English)

    王念

    2014-01-01

    White Portland cement is widely used due to its inherent advantages of whiteness and strength.GGBS has a high whiteness and high late strength characteristics.It is a linkd of new green building materials with low-carbon en-vironmental protection,and has the effect of low-carbon emission reduction.GGBS is considered to replace part of the clinker used for preparation of white cement.It is studied that white Portland cement is prepared with GGBS in differ-ent proportions to replace the white cement clinker or flying powder.The results show it has a significant improvement on the two main indicators of the strength and whiteness.%白色硅酸盐水泥由于其本身具有白度和强度的优势而广泛应用;矿渣微粉是一种具有高白度以及后期高强度等特点的低碳环保新型绿色建材,因而我们考虑将矿粉取代部分熟料用来配制白水泥,达到低碳减排的效果。通过研究发现将矿粉以不同的比例取代熟料或双飞粉配制出的白水泥在强度和白度两大指标上都有显著改善。

  4. Raw mix designing, clinkerization and manufacturing of high-strength Portland cement from the limestone and clay of Darukhula Nizampur, Nowshera District, North-West Frontier Province (N.W.F.P.), Pakistan

    Institute of Scientific and Technical Information of China (English)

    Noor-ul-Amin; Tahir Shah; Khurshid Ali

    2009-01-01

    This paper covers the detailed version of the potential raw material deposits at Darukhula and the adjacent areas of Nizampur, the manufacturing of high-strength Portland cement samples from the same material and comparison of the physical and chemical parameters for resulting cement with British and Pakistan standard specifications, which include compressive strength, setting time, consistency, lechatelier expansion, Blaine and insoluble residue. It was found that the raw material available in the study area meets the standard specifications and the area is feasible for the cement plant installation. The area can provide raw material which is quite sufficient for the running of a cement plant.

  5. Perbandingan Sifat Fisik Beton Yang Menggunakan Semen Portland Pozzolan Dan Semen Portland Tipe I

    OpenAIRE

    Yusnita, Heni

    2011-01-01

    The research about concrete by using the Portland pozzolan cement and Portland cement type I has been done with the variation of submersion time is 7, 14, 21, and 28 days. The test is done for physics of the concrete. The sample is made from the ingredients 1 cement : 2 sand : 3 pebble. The result of the researching shows that the used of the Portland pozzolan cement can raise the impact of the concrete as much as 9,15% from concrete which uses the Portland cement type I. Orther side for the ...

  6. Effect of Curing Regime on Degree of Al3+Substituting for Si4+in C-S-H Gels of Hardened Portland Cement Pastes

    Institute of Scientific and Technical Information of China (English)

    HU Chenguang; HU Shuguang; DING Qingjun; FENG Xiaoxin; HUANG Xiulin

    2014-01-01

    The effect of curing regime on degree of Al3+substituting for Si4+(Al/Si ratio) in C-S-H gels of hardened Portland cement pastes was investigated by 29Si magic angel spinning (MAS) nuclear magnetic resonance (NMR) with deconvolution technique. The curing regimes included the constant temperature (20, 40, 60 and 80℃) and variable temperature (simulated internal temperature of mass concrete with 60℃peak). The results indicate that constant temperature of 20℃is beneficial to substitution of Al3+for Si4+, and Al/Si ratio changes to be steady after 180 d. The increase of Al/Si ratio at 40℃is less than that at 20℃for 28 d. The other three regimes of high temperature increase Al/Si ratio only before 3 d, on the contrary to that from 3 to 28 d. However, the 20℃curing stage from 28 to 180 d at variable temperature regime, is beneficial to the increase of Al/Si ratio which is still lower than that at constant temperature regime of 20℃for the same age. A nonlinear relation exists between the Al/Si ratio and temperature variation or mean chain length (MCL) of C-S-H gels, furthermore, the amount of Al3+which can occupy the bridging tetrahedra sites in C-S-H structure is insufficient in hardened Portland cement pastes.

  7. Chemical composition, effective atomic number and electron density study of trommel sieve waste (TSW), Portland cement, lime, pointing and their admixtures with TSW in different proportions.

    Science.gov (United States)

    Kurudirek, Murat; Aygun, Murat; Erzeneoğlu, Salih Zeki

    2010-06-01

    The trommel sieve waste (TSW) which forms during the boron ore production is considered to be a promising building material with its use as an admixture with Portland cement and is considered to be an alternative radiation shielding material, also. Thus, having knowledge on the chemical composition and radiation interaction properties of TSW as compared to other building materials is of importance. In the present study, chemical compositions of the materials used have been determined using a wavelength dispersive X-ray fluorescence spectrometer (WDXRFS). Also, TSW, some commonly used building materials (Portland cement, lime and pointing) and their admixtures with TSW have been investigated in terms of total mass attenuation coefficients (mu/rho), photon interaction cross sections (sigma(t)), effective atomic numbers (Z(eff)) and effective electron densities (N(e)) by using X-rays at 22.1, 25keV and gamma-rays at 88keV photon energies. Possible conclusions were drawn with respect to the variations in photon energy and chemical composition.

  8. Propriedades mecânicas de materiais compósitos à base de cimento Portland e resina epoxi Mechanical properties of composite materials based on portland cement and epoxy resin

    Directory of Open Access Journals (Sweden)

    T. H. Panzera

    2010-03-01

    Full Text Available O estudo de materiais de alto desempenho e multifuncionais, como os compósitos poliméricos cimentícios, tem sido o foco de inúmeras pesquisas na indústria da construção civil. Este trabalho investiga o efeito da combinação de uma fase polimérica termorrígida, uma resina epóxi, com cimento Portland branco estrutural, seguido da avaliação da resistência à compressão e módulo de elasticidade. Este compósito, quando comparado individualmente com as suas matérias-prima originais, promove um aumento da resistência mecânica à compressão, redução da massa específica e, também uma mudança significativa do comportamento mecânico. As mudanças nas propriedades mecânicas estão associadas à hidratação da fase cimentícia na presença da resina, fato comprovado através da análise espectroscópica na região do infravermelho.The study of multi-functional materials of high performance, as the polymeric-cementitious composites, has been the focus of several researches in the industry of the civil engineering. This work investigates the effect of the combination of a thermorigid epoxy phase and the white Portland cement, followed by the evaluation of its compressive strength and modulus of elasticity. This composite, when the phases are individually compared, provides an increase of the compressive strength, a reduction of the density, and a significant change of the mechanical behaviour. The changes in mechanical behaviour are associated with the hydration of cement in the presence of resin, which was evident after infrared spectroscopy analysis.

  9. Evolución de la Porosidad de Pastas de Cemento Portland por la Incorporación de una Puzolana Natural Evolution of Porosity in Portland Cement Pastes by addition of Natural Pozzolan

    Directory of Open Access Journals (Sweden)

    J.L. Fernández

    2004-01-01

    Full Text Available Se ha determinado la evolución que se produce en la porosidad de las pastas elaboradas con cemento Portland para uso general (CPN IRAM 50000, al incorporarle una puzolana natural de la región, en distintas proporciones y en función del tiempo de curado. El ensayo de porosidad se realiza según Norma API-RP-40, basada en la ley de Boyle, por la cual se determina el volumen de los vacíos de las pastas. Este se determina por diferencia entre el volumen total del gas a una presión P1 de 6.9.10(5 Pa y el volumen calibrado de una celda donde se encuentra la muestra a presión atmosférica P0. Posteriormente, se ingresa en la curva de calibración del porosímetro y se obtienen los volúmenes de sólido de las mezclas. Como conclusión se demuestra que la porosidad de las pastas disminuye con el aumento de la cantidad de cemento reemplazado y del tiempo de curadoA determination was made of the evolution of porosity in Portland cement pastes for general usage (CPN IRAM 50000 by incorporating different proportions of natural pozzolan from the region, and as a function of curing time. The API-RP-40 norm based on Boyle´s law was used to measure the porosity, determining the paste effective void volume. This is done by calculating the difference between the total gas space at a pressure P1 of 6,9 .10(5 Pa and the calibrated volume of the cell at atmospheric pressure P0. Then the paste volume was obtained by porosimeter calibration curves. In conclusion, this study demonstrates that the porosity of pastes decreases as a function of the amount of cement replaced and time of cure

  10. Mineralogy and microstructure of two Mexican Portland cements for the confinement of radioactive waste; Mineralogia y microestructura de dos cementos mexicanos Portland para el confinamiento de desechos radiactivos

    Energy Technology Data Exchange (ETDEWEB)

    Galicia A, E. [Universidad Autonoma del Estado de Mexico, Facultad de Ciencias, Campus El Cerrillo, Piedras Blancas, Carretera Toluca-Ixtlahuaca Km. 15.5, Estado de Mexico (Mexico); Badillo A, V. E.; Ramirez S, J. R. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Nava E, N., E-mail: nasiega_181@hotmail.com [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, 07730 Mexico D. F. (Mexico)

    2014-10-15

    The cementitious materials are involved in the different stages of radioactive waste management because they are used for the waste immobilization in the container, as well as filling in the spaces between containers vaults and also as engineering barrier and construction material in civil construction site. Therefore, is necessary to have a study of commercial cement available nationwide involving solid timely analysis in order to identify which phases are responsible for confinement of radionuclides, if considered the most reactive phase -CSH- or called secondary phases. In this research the hydration products of cement are presented as well as its importance in the nuclear industry. The analysis and observation of the cement clinker and the hydration products on the manufactured pulps with two commercial cements resistant to sulphates was realized using the observation technique of solid X-ray diffraction and nuclear analytic techniques of Moessbauer spectroscopy and X-Ray Fluorescence. The results show the presence of calcium silicate hydrates in the amorphous phase and the presence of ettringite crystals and portlandite sheets is appreciated. The abundant iron phase called tetra calcium ferro aluminate has been identified by Moessbauer spectroscopy. (Author)

  11. 75 FR 4423 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-Portland Cement...

    Science.gov (United States)

    2010-01-27

    ... Cement Association Notice is hereby given that, on December 14, 2009, pursuant to Section 6(a) of the... Cement Association (``PCA'') has filed written notifications simultaneously with the Attorney General and... damages under specified circumstances. Specifically, Continental Cement, Hannibal, MO has been added as...

  12. Reuse of a residue from petrochemical industry with portland cement Reutilización de un residuo de la industria petroquímica como adición al cemento portland

    Directory of Open Access Journals (Sweden)

    Janneth Torres Agredo

    2012-06-01

    Full Text Available In this article the possibility of using waste from the petrochemical industry,as partial replacement of Portland cement is studied, evaluating the presenceof contaminants in the waste and the encapsulation, once it is confined on the cement. This has been done, in order to find a use to this residue without cause damage to the environment. This residue, called spent fluid catalytic cracking catalyst (FCC, is mainly formed by a type Y zeolite, which is dispersing in an inorganic oxides matrix. The toxicity characteristic leaching proceeding was applied, in mortars adding with 20% of FCC as Portland cement replacement. The results showed that the residue does not represent a problem from the point of view of the leaching of elements, such as As, Pb, Zn, Cr, and La, which were below to the permissible limits. Additionally, the pozzolanic activity of FCC was evaluated according to ASTM C311, where the efficiency of the residue as pozzolanic addition is demonstrated. With the results the importance of reusing a residue of the petrochemical industry is emphasized, that decreases the amount of cement to be used and improves the mechanical resistance of the materials containing it.En el presente artículo se estudia la posibilidad de utilizar un residuo de la industria petroquímica, como sustitución parcial del cemento Portland, evaluando la presencia de elementos contaminantes en el residuo y su encapsulación, una vez se haya confinado con el cemento. Lo anterior, con el fin de determinar si su uso como material de construcción, puede o no causar un efecto negativo al medio ambiente. El residuo, denominado catalizador usado de craqueo catalítico (FCC, es un material que está compuesto por una zeolita tipo Y, dispersa en una matriz de óxidos inorgánicos. Se aplicó la técnica de TCLP (del inglés Toxicity Characteristic Leaching Procedure, en morteros adicionados con un 20%, de FCC con respecto a la cantidad de cemento. Los resultados

  13. The influence of loading on the corrosion of steel in cracked ordinary Portland cement and high performance concretes

    Science.gov (United States)

    Jaffer, Shahzma Jafferali

    Most studies that have examined chloride-induced corrosion of steel in concrete have focused on sound concrete. However, reinforced concrete is seldom uncracked and very few studies have investigated the influence of cracked concrete on rebar corrosion. Furthermore, the studies that have examined the relationship between cracks and corrosion have focused on unloaded or statically loaded cracks. However, in practice, reinforced concrete structures (e.g. bridges) are often dynamically loaded. Hence, the cracks in such structures open and close which could influence the corrosion of the reinforcing steel. Consequently, the objectives of this project were (i) to examine the effect of different types of loading on the corrosion of reinforcing steel, (ii) the influence of concrete mixture design on the corrosion behaviour and (iii) to provide data that can be used in service-life modelling of cracked reinforced concretes. In this project, cracked reinforced concrete beams made with ordinary Portland cement concrete (OPCC) and high performance concrete (HPC) were subjected to no load, static loading and dynamic loading. They were immersed in salt solution to just above the crack level at their mid-point for two weeks out of every four (wet cycle) and, for the remaining two weeks, were left in ambient laboratory conditions to dry (dry cycle). The wet cycle led to three conditions of exposure for each beam: (i) the non-submerged region, (ii) the sound, submerged region and (iii) the cracked mid-section, which was also immersed in the solution. Linear polarization resistance and galvanostatic pulse techniques were used to monitor the corrosion in the three regions. Potentiodynamic polarization, electrochemical current noise and concrete electrical resistance measurements were also performed. These measurements illustrated that (i) rebar corroded faster at cracks than in sound concrete, (ii) HPC was more protective towards the rebar than OPCC even at cracks and (iii) there

  14. Potencialidades de um caulim calcinado como material de substituição parcial do cimento portland em argamassas Potentialities of a calcined kaolin as material of partial replacement of portland cement in mortars

    Directory of Open Access Journals (Sweden)

    Marilia P. de Oliveira

    2006-06-01

    Full Text Available A utilização de argilas calcinadas na forma de metacaulinita, como material pozolânico para argamassas e concretos, tem recebido atenção considerável nos últimos anos. Este trabalho objetivou avaliar o desempenho mecânico de argamassas, nas quais foi utilizado um caulim calcinado proveniente do Estado da Paraíba, como material de substituição parcial do cimento Portland. Utilizaram-se duas finuras do caulim: passando nas peneiras ABNT 200 (0,074 mm e 325 (0,044 mm e calcinados nas temperaturas de 700, 800 e 900 ºC pelo tempo de 2 h. As amostras foram caracterizadas através de análise química, análise térmica diferencial, difração de raios-X e área específica. Obteve-se o índice de atividade pozolânica com a cal e o cimento Portland. O percentual de substituição adotado foi de 0, 10, 20, 30 e 40%. A relação aglomerante: areia foi de 1:1,5 e a relação água/aglomerante fixada igual 0,4. O efeito da substituição parcial do cimento na argamassa foi avaliado através da resistência à compressão simples, nas idades de 7, 28 e 90 dias. As argamassas estudadas apresentaram resistência superior em relação à da referência, até o nível de 30% de substituição.The use of burnt clays, in the metakaolin form, as pozzolanic material for mortars and concretes has received a remarkable attention in the last years. This paper aimed to evaluate the mechanical property of mortars, in which a calcined kaolin originating from the State of Paraiba, was used as partial cement replacement material. Two finess of the kaolin were used: ABNT 200 (0.074 mm and 325 (0.044 mm and burnt at temperatures of 700, 800 and 900 ºC for a period of 2 h. Both materials were characterized by chemical analysis, differential thermal analysis, X-ray diffraction, specific area tests. The pozolanic activity index was obtanied using lime and cement Portland. The amounts of replacement were 10, 20, 30 and 40%, besides the reference mortar. The binder

  15. Inorganic contaminants attenuation in acid mine drainage by fly ash and fly ash-ordinary Portland cement (OPC) blends : column experiments

    Energy Technology Data Exchange (ETDEWEB)

    Gitari, W.M. [Venda Univ., Thohoyandou (South Africa). Dept. of Ecology and Resources Management, School of Environmental Studies; Petrik, L.F.; Etchebers, O. [Western Cape Univ., Bellville (South Africa). Environmental and Nanosciences Group, Dept. of Chemistry; Key, D.L. [Western Cape Univ., Bellville (South Africa). Dept. of Chemistry; Okujeni, C. [Western Cape Univ., Bellville (South Africa). Dept. of Earth Sciences

    2010-07-01

    The infiltration of acid mine drainage (AMD) material into mine voids is one of the environmental impacts of underground coal mining. In this study, the mitigation of AMD in a mine void was simulated in laboratory conditions. Various mixtures of fly ash, solid residues, and Portland cement were added to packed columns over a 6-month period. The fly ash additions generated near-neutral to alkaline pH levels, which in turn induced precipitation, co-precipitation, and adsorption contaminant attenuation mechanisms. A modelling study demonstrated that the precipitation of ferrihydrite, Al-hydroxides, Al-oxyhydroxysulphates, gypsum, ettringite, manganite, and rhodochrosite lowered contaminant levels. Results of the study indicated that the pH regime and acidity level of the AMD strongly influenced both the leaching of the toxic trace elements as well as the attenuation of the AMD. 3 refs., 2 figs.

  16. Effect of High Doses of Chemical Admixtures on the Freeze-Thaw Durability of Portland Cement Concrete

    Science.gov (United States)

    2002-02-01

    volume (Neville 1988). The hydrated cement is often referred to as cement gel, which has a characteristic porosity of about 28% ( Mindess and Young...Structure, Properties, and Materials. New York: Prentice-Hall. Mindess , S., and J.F. Young (1981) Concrete. New York: Prentice-Hall. Neville, A.M

  17. Effect of Exposure to Portland Cement Dust on the Periodontal Status and on the Outcome of Non-Surgical Periodontal Therapy

    Science.gov (United States)

    Abdelhamid, Alaa

    2016-01-01

    Background Cement dust contains heavy metals like nickel, cobalt, lead and chromium, pollutants hazardous to the biotic environment, with adverse impact for vegetation, human and animal health and ecosystems. Objective To investigate if long term exposure to cement dust can affect the periodontal health and affect the outcome of non-surgical periodontal therapy. Methods A total of sixty subjects were included in this study. Forty patients with chronic periodontitis were grouped into; Group I comprised of 20 patients with chronic periodontitis working in the Portland Cement Company and Group II comprised of 20 patients with chronic periodontitis who does not work in cement factories nor live near any of them. Twenty healthy subjects were included in this study as healthy control group (Group III). Clinical parameters including gingival index (GI), plaque index (PI), pocket depth (PD) and clinical attachment loss (CLA) were scored for all patients before and after periodontal therapy. All patients received non-surgical periodontal therapy together with strict oral hygiene program for one month. Gingival crevicular fluid (GCF) samples were collected from both groups at baseline and one month after periodontal therapy. Real time PCR (RT-PCR) was used to analyze the GCF samples for detection and assessment of the levels of IL-1β and TNFα. Results The two studied groups responded well to non-surgical periodontal treatment and there was no significant difference between GI and GII (P>0.05). The levels of TNFα was higher in GI than in GII before and after periodontal therapy (P0.05), but represented with a highly significant difference between G1 and GII after periodontal therapy (Psurgical periodontal treatment but it affects the levels of the pro-inflammatory mediators leading to more periodontal tissue destruction. PMID:27610057

  18. Feasibility of using in situ fusion for the determination of Co, Cr and Mn in Portland cement by direct solid sampling graphite furnace atomic absorption spectrometry

    Science.gov (United States)

    Intima, Danielle Polidorio; de Oliveira, Elisabeth; Oliveira, Pedro Vitoriano

    2009-06-01

    In situ fusion on the boat-type graphite platform has been used as a sample pretreatment for the direct determination of Co, Cr and Mn in Portland cement by solid sampling graphite furnace atomic absorption spectrometry (SS-GF AAS). The 3-field Zeeman technique was adopted for background correction to decrease the sensitivity during measurements. This strategy allowed working with up to 200 µg of sample. The in situ fusion was accomplished using 10 µL of a flux mixture 4.0% m/v Na 2CO 3 + 4.0% m/v ZnO + 0.1% m/v Triton® X-100 added over the cement sample and heated at 800 °C for 20 s. The resulting mould was completely dissolved with 10 µL of 0.1% m/v HNO 3. Limits of detection were 0.11 µg g - 1 for Co, 1.1 µg g - 1 for Cr and 1.9 µg g - 1 for Mn. The accuracy of the proposed method has been evaluated by the analysis of certified reference materials. The values found presented no statistically significant differences compared to the certified values (Student's t-test, p < 0.05). In general, the relative standard deviation was lower than 12% ( n = 5).

  19. Assessment of Pozzolanic Activity Using Methods Based on the Measurement of Electrical Conductivity of Suspensions of Portland Cement and Pozzolan

    OpenAIRE

    Sergio Velázquez; JOSÉ M. MONZÓ; María V. Borrachero; Jordi Payá

    2014-01-01

    The use of methods based on measuring electrical conductivity to assess pozzolanic activity has recently been used primarily in aqueous suspensions of pozzolan: calcium hydroxide. However, the use of similar methods in suspensions of cement with pozzolans has not been widely studied. This paper proposes a new method for rapid assessment of the pozzolanic activity of mineral admixtures in aqueous cement suspensions. In this study, the conditions for the application of the method were optimized...

  20. Potencial da cinza do bagaço da cana-de-açúcar como material de substituição parcial de cimento Portland Potential of sugarcane bagasse ash as a partial replacement material for Portland cement

    Directory of Open Access Journals (Sweden)

    Marcos O. de Paula

    2009-06-01

    Full Text Available Este trabalho, voltado para a avaliação do potencial da cinza do bagaço da cana-de-açúcar (CBC como material de substituição parcial do cimento Portland em argamassa, objetivou apresentar opção viável para a destinação deste resíduo, cuja quantidade gerada aumentará significativamente nos próximos anos, em decorrência da ampliação do setor de produção de álcool combustível; além disso, o emprego da CBC como adição mineral, substituindo parte do cimento em argamassas e concretos, contribui para a redução do impacto ambiental desses materiais, em boa parte decorrente da produção do cimento. O procedimento experimental abordou não só caracterização da CBC mas também a avaliação, através de ensaios físicos e mecânicos, em que os resultados mostraram que o bagaço apresenta rendimento de CBC de 10%, com a cinza sendo composta de 84% de SiO2 e 5% de Carbono. A sílica na CBC apresenta-se na fase amorfa e nas fases cristalinas de cristobalita e quartzo. Os índices de atividade pozolânica comprovam a reatividade da CBC. Do ponto de vista da resistência à compressão, argamassas com teores de CBC entre 0 e 30% indicaram a possibilidade de substituição de até 20% do cimento pela CBC.This study is focused on the evaluation of the effects of the partial replacement of Portland cement by sugarcane bagasse ash (CBC in mortars. The main objective was to find a suitable destination for an agricultural residue generated in an increasing amount in Brazil, as a result of the boom of the use of ethanol as an alternative fuel to gasoline. Also, the use of CBC as a mineral admixture in mortars and concretes contributes to a decrease in the environmental impact of these materials related to cement production. Experimental techniques were applied both for the CBC characterization and for the evaluation of its use as a mineral admixture in mortars, based on mechanical and physical tests. The yield of CBC from sugarcane

  1. Application of Neutron imaging in pore structure of hydrated wellbore cement: comparison of hydration of H20 with D2O based Portland cements

    Science.gov (United States)

    Dussenova, D.; Bilheux, H.; Radonjic, M.

    2012-12-01

    Wellbore Cement studies have been ongoing for decades. The studies vary from efforts to reduce permeability and resistance to corrosive environment to issues with gas migration also known as Sustained Casing Pressure (SCP). These practical issues often lead to health and safety problems as well as huge economic loss in oil and gas industry. Several techniques have been employed to reduce the impact of gas leakage. In this study we purely focus on expandable liners, which are introduced as part of oil well reconstruction and work-overs and as well abandonment procedures that help in prevention of SCP. Expandable liner is a tube that after application of a certain tool can increase its diameter. The increase in diameter creates extra force on hydrated cement that results in reducing width of interface fractures and cement-tube de-bonding. Moreover, this also causes cement to change its microstructure and other porous medium properties, primarily hydraulic conductivity. In order to examine changes before and after operations, cement pore structure must be well characterized and correlated to cement slurry design as well as chemical and physical environmental conditions. As modern oil well pipes and tubes contain iron, it is difficult to perform X-ray tomography of a bulk measurement of the cement in its wellbore conditions, which are tube wall-cement-tube wall. Neutron imaging is a complementary technique to x-ray imaging and is well suited for detection of light elements imbedded in metallic containers. Thus, Neutron Imaging (NI) is investigated as a tool for the detection of pore structure of hydrated wellbore cement. Recent measurements were conducted at the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor (HFIR) neutron imaging facility. NI is is highly sensitive to light elements such as Hydrogen (H). Oil well cements that have undergone a full hydration contain on average 30%-40% of free water in its pore structure. The unreacted water is the main

  2. Microscopic analysis of dog dental pulp after pulpotomy and pulp protection with mineral trioxide aggregate and white Portland cement Análise microscópica da polpa dental de cães após pulpotomia e proteção pulpar com agregado de trióxido mineral e cimento Portland branco

    Directory of Open Access Journals (Sweden)

    Renato Menezes

    2004-06-01

    Full Text Available Considering previous studies on the similarity between the chemical composition of the mineral trioxide aggregate and the Portland cement, the purpose of this study was to investigate the pulp response of dog's teeth after pulpotomy and direct pulp protection with MTA Angelus and white Portland cement. Thirty eight pulp remnants were protected with these materials. One hundred and twenty days after treatment, the animals were sacrificed and the specimens removed and prepared for histological analysis. Both materials demonstrated the same results when used as pulp capping materials, inducing hard tissue bridge formation and maintaining pulp vitality in all specimens. The MTA Angelus and the white Portland cement showed to be effective as pulp protection materials following pulpotomy.Considerando estudos anteriores sobre a similaridade entre a composição química do agregado de trióxido mineral e o cimento Portland, o objetivo deste estudo foi investigar a resposta pulpar de dentes de cães após pulpotomia e proteção pulpar direta com MTA Angelus e cimento Portland branco. Trinta e oito remanescentes pulpares foram recobertos com esses materiais. Cento e vinte dias após o tratamento, os animais foram sacrificados e os espécimes removidos e preparados para análise histológica. Ambos os materiais demonstraram os mesmos resultados quando utilizados como materiais de capeamento pulpar, induzindo a formação de ponte de tecido mineralizado e mantendo a vitalidade pulpar em todos os espécimes. Ambos matérias se mostraram efetivos como protetores pulpares após pulpotomia em dentes de cães.

  3. Gel/Space Ratio Evolution in Ternary Composite System Consisting of Portland Cement, Silica Fume, and Fly Ash

    Directory of Open Access Journals (Sweden)

    Mengxue Wu

    2017-01-01

    Full Text Available In cement-based pastes, the relationship between the complex phase assemblage and mechanical properties is usually described by the “gel/space ratio” descriptor. The gel/space ratio is defined as the volume ratio of the gel to the available space in the composite system, and it has been widely studied in the cement unary system. This work determines the gel/space ratio in the cement-silica fume-fly ash ternary system (C-SF-FA system by measuring the reaction degrees of the cement, SF, and FA. The effects that the supplementary cementitious material (SCM replacements exert on the evolution of the gel/space ratio are discussed both theoretically and practically. The relationship between the gel/space ratio and compressive strength is then explored, and the relationship disparities for different mix proportions are analyzed in detail. The results demonstrate that the SCM replacements promote the gel/space ratio evolution only when the SCM reaction degree is higher than a certain value, which is calculated and defined as the critical reaction degree (CRD. The effects of the SCM replacements can be predicted based on the CRD, and the theological predictions agree with the test results quite well. At low gel/space ratios, disparities in the relationship between the gel/space ratio and the compressive strength are caused by porosity, which has also been studied in cement unary systems. The ratio of cement-produced gel to SCM-produced gel ( G C to G S C M ratio is introduced for use in analyzing high gel/space ratios, in which it plays a major role in creating relationship disparities.

  4. Solidificación-Estabilización de Cromo, Níquel y Plomo en una Matriz Sólida de Hormigón Fabricada con Cemento Portland Solidification-Stabilization of Chromium, Nickel and Lead in a Concrete Solid Matrix of Portland Cement

    Directory of Open Access Journals (Sweden)

    René A Lara-Díaz

    2009-01-01

    Full Text Available Se validó la técnica de cementación como alternativa para la solidificación-estabilización de residuos sintéticos de metales pesados, cromo, níquel y plomo, usando probetas sólidas de hormigón de cemento Portland. El proceso de cementación se realiza a partir de una mezcla base para obtener hormigón con resistencia a la compresión de 29.4 N/mm², los metales fueron incorporados como sales metálicas en el agua de amasado. Se realizaron pruebas de resistencia a la compresión, lixiviación de metales por la prueba PECT con absorción atómica y se calculó la eficiencia de retención. El hormigón fabricado con cemento Portland es adecuado para su uso en la solidificación-estabilización de níquel y plomo a una concentración máxima de 0.43% para níquel y 1.94% para plomo.The technique of cementation was validated as an alternative method for the solidification-stabilization of heavy metal synthetic wastes, chromium, nickel and lead, using concrete solid cylinders made of Portland cement. The cementation process takes place starting with a concrete mixture base with compressive strength of 29.4 N/mm². Metals were incorporated as metallic salts in the mixing water. Tests of compressive strength, leaching of metals by PECT with atomic absorption were performed and retention efficiencies were calculated. Concrete made with Portland cement is appropriate for the solidification-stabilization of nickel and lead, with maximum concentrations of 0.43% of nickel and 1.94% of lead in concrete.

  5. Assessment of Pozzolanic Activity Using Methods Based on the Measurement of Electrical Conductivity of Suspensions of Portland Cement and Pozzolan

    Directory of Open Access Journals (Sweden)

    Sergio Velázquez

    2014-11-01

    Full Text Available The use of methods based on measuring electrical conductivity to assess pozzolanic activity has recently been used primarily in aqueous suspensions of pozzolan: calcium hydroxide. However, the use of similar methods in suspensions of cement with pozzolans has not been widely studied. This paper proposes a new method for rapid assessment of the pozzolanic activity of mineral admixtures in aqueous cement suspensions. In this study, the conditions for the application of the method were optimized, such as time, temperature, w/c ratio and dosage procedure. Finally, results are presented from the application of this method for characterizing the pozzolanic activity of the spent catalytic cracking catalyst. These results corroborate as previously reported, namely the high reactivity of this pozzolan obtained by other methods, such as thermogravimetry or evolution of the mechanical strength. In addition, the pozzolanic activity of the catalyst was compared with other pozzolans such as metakaolin and silica fume.

  6. The use of electrical impedance spectroscopy for monitoring the hydration products of Portland cement mortars with high percentage of pozzolans

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, J.M. [Departamento de Física Aplicada, Universitat Politècnica de València, Camino de Vera, 46022, Valencia (Spain); Fita, I.C., E-mail: infifer@fis.upv.es [Departamento de Física Aplicada, Universitat Politècnica de València, Camino de Vera, 46022, Valencia (Spain); Soriano, L.; Payá, J.; Borrachero, M.V. [ICITECH, Instituto de Ciencia y Tecnología del Hormigón, Universitat Politècnica de València (Spain)

    2013-08-15

    In this paper, mortars and pastes containing large replacement of pozzolan were studied by mechanical strength, thermogravimetric analysis (TGA), scanning electronic microscopy (SEM), mercury intrusion porosimetry (MIP) and electrical impedance spectroscopy (EIS). The effect of metakaolin (35%) and fly ash (60%) was evaluated and compared with an inert mineral addition (andalusite). The portlandite content was measured, finding that the pozzolanic reaction produced cementing systems with all portlandite fixed. The EIS measurements were analyzed by the equivalent electrical circuit (EEC) method. An EEC with three branches in parallel was applied. The dc resistance was related to the degree of hydration and allowed us to characterize plain and blended mortars. A constant phase element (CPE) quantified the electrical properties of the hydration products located in the solid–solution interface and was useful to distinguish the role of inert and pozzolanic admixtures present in the cement matrix.

  7. Quantitative Analysis of the Mineralogical Stages of the Clinkers of Portland Cement. Qualitative and Quantitative Analysis, by Infrared Spectroscopy of the Mineralogical Stages of the Clinker of Portland Cement

    Directory of Open Access Journals (Sweden)

    Käsner, Bernd

    1972-09-01

    Full Text Available Not availablePara la determinación cuantitativa de las fases mineralógicas del clinker de cemento portland, tan sólo se emplean el análisis microscópico y el de difracción de rayos X. Ambas técnicas exigen una preparación de muestras muy cuidadosa, lo que lleva bastante tiempo. A causa de estas circunstancias surge el interés de desarrollar un procedimiento con el que se pueda obtener resultados de exactitud y con poco trabajo, basado en la espectroscopia infrarroja. En principio existen dificultades, tanto en el método de trabajo como de interpretación de resultados. Por ejemplo, la formación y composición de las fases del clíñker se hallan sometidas a variaciones; por otra parte, aún no se ha llegado a elaborar un procedimiento para estudio por IR de sistemas que contengan varios componentes inorgánicos en estado sólido. Se ha pensado en la realización previa de análisis elementales, con los que se aclararían los de las fases minerales de los clínkeres, ya que no está aún suficientemente resuelto —a pesar de la importancia que esto representa— el análisis cuantitativo de estas fases.

  8. Grout Impregnation of Pre-Placed Recycled Concrete Pavement (RCP) for Rapid Repair of Deteriorated Portland Cement Concrete Airfield Pavement

    Science.gov (United States)

    2007-04-01

    Hammitt (1985) also reports a high failure rate when using cold mix asphalt for crater repairs and recommended that it be abandoned as a technique...cement-treated base, embankment base material, and aggregate for asphalt paving mixtures . RCP has been used successfully for all of these types of...that recycled asphalt pavement ( RAP ) and RCP have a substantial history of usage in pavement construction. He reports that cost savings of 20 to

  9. Studies on potential of Portland cement mortar for binding of waterworks sludge to reduce heavy metal leaching

    Indian Academy of Sciences (India)

    PARAMALINGGAM THANALECHUMI; ABDULL RAHIM MOHD YUSOFF; MOHANADOSS PONRAJ; HANIM AWAB

    2016-03-01

    The investigation of heavy metal leaching and physicochemical properties of cement-solidified waterworks sludge (CMWWS) formed by incorporating waterworks sludge (WWS) into cement mortar was carried out. The chemical composition, compressive strength and other physicochemical properties of the CMWWS cube specimens were determined using field emission scanning electron microscopy (FESEM), X-ray diffractometry (XRD) and Fourier transform-infrared spectroscopy (FTIR). The major type of chemical components present in CMWWS was found to be Al and Fe. The increasing amount of WWS added to cement mortar resulted in the increasing of organic matter, urchin-like morphology and clear peak intensity. At the end of 28 days of curing, the soaking solution became strongly basic and CMWWS cube specimens leached out higher amount of heavy metals. The compressive strength of CMWWS increased up to a WWS percentage of 10%, and basic (pH [ 7) curing solution was found to be better than water for curing purposes. It is concluded that solidification–stabilisation (S/S) technique is able to effectively reduce the leaching of heavy metals from the WWS and CMWWS containing up to 10% WWS can be used as construction material.

  10. Examination of solidified and stabilized matrices as a result of solidification and stabilization process of arseniccontaining sludge with portland cement and lime

    Directory of Open Access Journals (Sweden)

    Tanapon Phenrat

    2004-02-01

    Full Text Available By solidification and stabilization (S/S with Portland cement and lime, it is possible to reduce arsenic concentration in leachate of the arsenic-containing sludge from arsenic removal process by coagulation with ferric chloride. From the initial arsenic concentration in leachate of unsolidified /unstabilized sludge which was around 20.75 mg/L, the arsenic concentrations in leachate of solidified/stabilized waste were reduced to 0.3, 0.58, 1.09, and 1.85 mg/L for the waste-to-binder ratios of 0.15, 0.25, 0.5, and 1, respectively, due tothe formation of insoluble calcium-arsenic compounds. To be more cost effective for the future, alternative uses of these S/S products were also assessed by measurement of compressive strength of the mortar specimens. It was found that the compressive strengths of these matrices were from 28 ksc to 461 ksc. In conclusion, considering compressive strength and leachability of the solidified matrices, some of these solidified/ stabilized products have potential to serve as an interlocking concrete paving block.

  11. Sorption kinetics of superabsorbent polymers (SAPs) in fresh Portland cement-based pastes visualized and quantified by neutron radiography and correlated to the progress of cement hydration

    Energy Technology Data Exchange (ETDEWEB)

    Schroefl, Christof, E-mail: christof.schroefl@tu-dresden.de [Technische Universität Dresden, Fakultät Bauingenieurwesen, Institut für Baustoffe, DE-01062 Dresden (Germany); Mechtcherine, Viktor [Technische Universität Dresden, Fakultät Bauingenieurwesen, Institut für Baustoffe, DE-01062 Dresden (Germany); Vontobel, Peter; Hovind, Jan; Lehmann, Eberhard [Paul Scherrer Institut, Laboratory for Neutron Scattering and Imaging, CH-5232 Villigen/AG (Switzerland)

    2015-09-15

    Water sorption of two superabsorbent polymers in cement-based pastes has been characterized by neutron radiography. Cement pastes with W/C of 0.25 and 0.50 and one additionally containing silica fume (W/C = 0.42) were investigated. The SAPs differed in their inherent sorption kinetics in extracted cement pore solution (SAP 1: self-releasing; SAP 2: retentive). Desorption from SAP 1 started very early after paste preparation. Hence, its individual non-retentiveness governs its behavior only. SAP 2 released water into all matrices, but its kinetics were different. In the paste with the highest W/C, some moderate water release was recorded from the beginning. In the other two pastes, SAP 2 retained its stored liquid during the dormant period, i.e., up to the percolation threshold. Intense desorption then set in and continued throughout the acceleration period. These findings explain the pronouncedly higher efficiency of SAP 2 as internal curing admixture as compared to SAP 1.

  12. 电阻率法测定硅酸盐水泥水化活化能%Activation Energy of Portland Cement Hydration by Electrical Resistivity Measurement

    Institute of Scientific and Technical Information of China (English)

    魏小胜; 肖莲珍

    2011-01-01

    研究了温度对水泥水化时电阻率的影响情况,建立了用于估算电阻率极大值的双曲线方程,提出根据不同温度时的电阻率可以计算孔隙液相活化能(Eas)和水化反应的活化能(Ear).试验所用水泥浆体试样的水灰比分别为0.30、0.35、0.40、0.45和0.55,养护温度分别为15、20℃和30℃,测试时间均为72h.为消除温度对孔隙液相离子迁移的影响,在15℃和30℃测得的电阻率值分别以20℃为基准进行了校正,分析了温度对水泥水化产物形成的影响.研究表明:当水灰比从0.55减小到0.30时.Eas从16.5kJ/mol增大到25.7kJ/mol,这是因为低水灰比水泥浆体的液相离子浓度较大.计算表明:硅酸盐水泥水化反应的活化能Ear为37.2 kJ/mol,这与ASTM C1074的推荐值(40 kJ/mol)比较接近.在不同养护温度下得到的电阻率双曲线方程表明:在所测试的温度范围内,温度越低,电阻率的极大值越大.%Temperature effect on the electrical resistivity of Portland cement pastes during first 72 h was investigated. The experiments were conducted on the cement pastes with various water cement ratios of 0.30, 0.35, 0.40, 0.45, 0.55 at different curing temperatures of 15, 20 and 30 ℃. The hyperbolic equation for each sample was established to estimate the ultimate resistivity. The electrical resistivity at various temperatures can determinate the activation energy for the liquid solution in pores (Eas) and the activation energy for hydration reaction (Ear). The electrical resistivities at 15 and 30 ℃ are obtained based on the value at 20 ℃ to eliminate the effect of temperature on the ionic mobility in the liquid solutions. The Eas increased with the decrease of water cement ratio due to a higher ion concentration in a lower water cement ratio paste solution, and the Eas ranged from 16.5 to 25.7 kJ/mol. The activation energy of cement hydration determined was 37.2 k J/mol, which was similar to the value recommended by the

  13. Changes in constituent equilibrium leaching and pore water characteristics of a Portland cement mortar as a result of carbonation.

    Science.gov (United States)

    Garrabrants, A C; Sanchez, F; Kosson, D S

    2004-01-01

    Two equilibrium-based characterization protocols were applied to ground samples of a cement-based material containing metal oxide powders in both noncarbonated and carbonated states. The effects of carbonation were shown through comparison of (i) material buffering capacity, (ii) constituent equilibrium as a function of leachate pH, and (iii) constituent solubility and release as a function of liquid-to-solid (LS) ratio. As expected, the material alkalinity was significantly neutralized during carbonation. In addition, carbonation of the cement material led to the formation of calcium carbonate and a corresponding increase in arsenic release across the entire pH range. The solubility as a function of pH for lead and copper was lower in the alkaline pH range (pH>9) for carbonated samples compared with the parent material. When solubility and release as a function of LS ratio was compared, carbonation was observed to decrease calcium solubility, sodium and potassium release, and ionic strength. In response to carbonate solid formation, chloride and sulfate release as a function of LS ratio was observed to increase. Trends in constituent concentration as a function of LS ratio were extrapolated to estimate pore water composition at a 0.06 mL/g LS ratio. Significant differences were observed upon comparison of estimated pore water composition to leachate concentrations extracted at LS ratio of 5 mL/g. These differences show that practical laboratory extractions cannot be assumed directly representative of pore water concentrations.

  14. Solidification Coal Fly Ash on A Textile Factory as Allelochemi to Alternative Portland Cement Wall House Anti-Moss

    Directory of Open Access Journals (Sweden)

    Prabang Setyono

    2012-01-01

    Full Text Available This research for the application of coal waste as fly ash for mixture cement the stonewall anti moss which hypothesis upon which Allelochemi. Using the coal waste  represent one of program of environment conservation which is in the form of 3R ( Reuse, Recycle And Reduce, so this research can be made pilot project in development and substance invention of anti moss and make friends with the environment. The research target is identifying moss type in region Surakarta, knowing mixture concentration having technical eligibility of construction and TCLP test ( Toxicity Characteristic Leachate Procedure and justification of  LC50 and LD50. Research was carried out in laboratory by in phases following: casting of Mixture cement and fly ash: test of mechanic strength, test of resilience to moss growth, test of ability adhesive to wall paint, making solid Matrix. Continued by a test Depress to use the Technotest Modena Italy then Test the assimilated: Chemical Ekstraksi in step by step. Fraction 1 until Faction 5, TCLP (Toxicity Characteristic Leaching Procedure Standard, TCLP ( Toxicity Characteristic Leaching Procedure Progressive and TCLP (Toxycity Characteristic Leaching Procedure Modification. The Allelochemi form be observed by means of  Microscopic observation. The results revealed that moss type found in region of Surakarta:  Dicranella heteromalla, Funaria hygrometrica  ( Hedwig., Rhodobryum giganteum ( Schwaegr. Par., Pogonatum contortum ( Brid.. Mixture prosentase of  fly ash which still fulfill the technical standard of concrete building construction is 20 - 40 %. Value LC 50 to animal test the goldfish 8950 ppm and  the LD 50 value to animal test the mencit 30,35 mg / kg BB so that near no toxic. The resistance process  of  moss growing at coat cement also got concentration 20 - 40 % through allelochemi mechanism. Ever greater of  fly ash prosentase at growth media the moss hence assess the heavy metal accumulation of  Pb, Cr

  15. Kinetic and morphological differentiation of Ettringites in plain and blended Portland cements using Metakaolin and the ASTM C 452-68 test. Part I: kinetic differentiation

    Directory of Open Access Journals (Sweden)

    Talero, R.

    2008-12-01

    Full Text Available In this first part of the study, the results obtained in prior research with XRD and SEM, as well as the Le Chatelier-Ansttet test were confirmed with the ASTM C 452-68 test. To this end, 20%, 30% and 40% metakaolin (MK was added to ten Portland cements, six OPCs and four SRPCs. Both the ten plain PCs and the 30 metakaolin (MK blends were tested for two years under ASTM C 452-68 specifications, determining not only the percentage increase in length, ΔL(%, of the specimens, but also the sulphate content in the curing water. Other parameters studied included: chemical analysis of the cementitious materials used and specific properties of some of the cements tested.The experimental results, ΔL(% versus time, re-confirmed that the formation rate of ettringite from the reactive alumina, Al2O3r-, present in the pozzolan must be substantially higher than the formation rate of ettringite from the C3A present in the PC. This was verified by the variation of the sulphate content in the specimen curing water throughout the test. In light of those findings, in this article these two types of ettringite are denominated rapid forming ettringite or ett-rf, and slow forming ettringite or ett-lf.En esta Parte I de la investigación, se han logrado verificar mediante el ensayo ASTM C 452-68, los resultados obtenidos en anteriores investigaciones realizadas con DRX y SEM y el ensayo Le Chatelier-Ansttet. Para ello, a 10 cementos Portland –6 CPO y 4 CPRS– se les añadió 20%, 30% y 40% de metakaolín (MK. Tanto los 10 CP como los 30 de sus mezclas con metakaolín (MK, se ensayaron durante 2 años, mediante dicho método ASTM C 452-68, y a sus probetas no sólo se les determinó su incremento porcentual de longitud, ΔL(%, sino además, el contenido de sulfatos de sus aguas de conservación. Otras determinaciones complementarias fueron: análisis químico de los materiales cementiceos utilizados y propiedades específicas de algunos cementos ensayados

  16. An ex-vivo comparative study of root-end marginal adaptation using grey mineral trioxide aggregate, white mineral trioxide aggregate, and Portland cement under scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Akash Kumar Baranwal

    2015-01-01

    Full Text Available Context: Where nonsurgical endodontic intervention is not possible, or it will not solve the problem, surgical endodontic treatment must be considered. A major cause of surgical endodontic failures is an inadequate apical seal, so the use of the suitable substance as root-end filling material that prevents egress of potential contaminants into periapical tissue is very critical. Aims: The aim of the present ex-vivo study was to compare and evaluate the three root-end filling materials of mineral trioxide aggregate (MTA family (white MTA [WMTA], grey MTA [GMTA] and Portland cement [PC] for their marginal adaptation at the root-end dentinal wall using scanning electron microscopy (SEM. Materials and Methods: Sixty human single-rooted teeth were decoronated, instrumented, and obturated with Gutta-percha. After the root-end resection and apical cavity preparation, the teeth were randomly divided into three-experimental groups (each containing 20 teeth and each group was filled with their respective experimental materials. After longitudinal sectioning of root, SEM examination was done to determine the overall gap between retrograde materials and cavity walls in terms of length and width of the gap (maximum at the interface. Descriptive statistical analysis was performed to calculate the means with corresponding standard errors, median and ranges along with an analysis of variance and Tukey′s test. Results: The least overall gap was observed in GMTA followed by PC and WMTA. While after statistically analyzing the various data obtained from different groups, there was no significant difference among these three groups in terms of marginal adaptation. Conclusion: GMTA showed the best overall adaptation to root dentinal wall compared to PC and WMTA. Being biocompatible and cheaper, the PC may be an alternative but not a substitute for MTA.

  17. In vitro antibacterial activity of a novel resin-based pulp capping material containing the quaternary ammonium salt MAE-DB and Portland cement.

    Directory of Open Access Journals (Sweden)

    Yanwei Yang

    Full Text Available BACKGROUND: Vital pulp preservation in the treatment of deep caries is challenging due to bacterial infection. The objectives of this study were to synthesize a novel, light-cured composite material containing bioactive calcium-silicate (Portland cement, PC and the antimicrobial quaternary ammonium salt monomer 2-methacryloxylethyl dodecyl methyl ammonium bromide (MAE-DB and to evaluate its effects on Streptococcus mutans growth in vitro. METHODS: The experimental material was prepared from a 2 : 1 ratio of PC mixed with a resin of 2-hydroxyethylmethacrylate, bisphenol glycerolate dimethacrylate, and triethylene glycol dimethacrylate (4 : 3 : 1 containing 5 wt% MAE-DB. Cured resin containing 5% MAE-DB without PC served as the positive control material, and resin without MAE-DB or PC served as the negative control material. Mineral trioxide aggregate (MTA and calcium hydroxide (Dycal served as commercial controls. S. mutans biofilm formation on material surfaces and growth in the culture medium were tested according to colony-forming units (CFUs and metabolic activity after 24 h incubation over freshly prepared samples or samples aged in water for 6 months. Biofilm formation was also assessed by Live/Dead staining and scanning electron microscopy. RESULTS: S. mutans biofilm formation on the experimental material was significantly inhibited, with CFU counts, metabolic activity, viability staining, and morphology similar to those of biofilms on the positive control material. None of the materials affected bacterial growth in solution. Contact-inhibition of biofilm formation was retained by the aged experimental material. Significant biofilm formation was observed on MTA and Dycal. CONCLUSION: The synthesized material containing HEMA-BisGMA-TEGDMA resin with MAE-DB as the antimicrobial agent and PC to support mineralized tissue formation inhibited S. mutans biofilm formation even after aging in water for 6 months, but had no inhibitory effect on

  18. An ex-vivo comparative study of root-end marginal adaptation using grey mineral trioxide aggregate, white mineral trioxide aggregate, and Portland cement under scanning electron microscopy

    Science.gov (United States)

    Baranwal, Akash Kumar; Paul, Mohan L.; Mazumdar, Dibyendu; Adhikari, Haridas Das; Vyavahare, Nishant K.; Jhajharia, Kapil

    2015-01-01

    Context: Where nonsurgical endodontic intervention is not possible, or it will not solve the problem, surgical endodontic treatment must be considered. A major cause of surgical endodontic failures is an inadequate apical seal, so the use of the suitable substance as root-end filling material that prevents egress of potential contaminants into periapical tissue is very critical. Aims: The aim of the present ex-vivo study was to compare and evaluate the three root-end filling materials of mineral trioxide aggregate (MTA) family (white MTA [WMTA], grey MTA [GMTA] and Portland cement [PC]) for their marginal adaptation at the root-end dentinal wall using scanning electron microscopy (SEM). Materials and Methods: Sixty human single-rooted teeth were decoronated, instrumented, and obturated with Gutta-percha. After the root-end resection and apical cavity preparation, the teeth were randomly divided into three-experimental groups (each containing 20 teeth) and each group was filled with their respective experimental materials. After longitudinal sectioning of root, SEM examination was done to determine the overall gap between retrograde materials and cavity walls in terms of length and width of the gap (maximum) at the interface. Descriptive statistical analysis was performed to calculate the means with corresponding standard errors, median and ranges along with an analysis of variance and Tukey's test. Results: The least overall gap was observed in GMTA followed by PC and WMTA. While after statistically analyzing the various data obtained from different groups, there was no significant difference among these three groups in terms of marginal adaptation. Conclusion: GMTA showed the best overall adaptation to root dentinal wall compared to PC and WMTA. Being biocompatible and cheaper, the PC may be an alternative but not a substitute for MTA. PMID:26430305

  19. Research Progress in Applications of Calcium Sulphoaluminate Modified Portland Cement%硫铝酸钙改性硅酸盐水泥应用研究进展∗

    Institute of Scientific and Technical Information of China (English)

    葛大顺; 马素花; 李伟峰; 于锦; 沈晓冬; 汤国芳; 蔡建; 管娟

    2015-01-01

    Calcium sulphoaluminate modified Portland cement clinker has excellent characteristics of ordinary Portland cement clinker and sulphoaluminate cement clinker.Meanwhile this cement clinker has superior stimulating effect for fly-ash.These advantages confer SMP broad application prospects.Herein,the properties and hydration characteristics of SMP are summarized,and the composite properties of SMP with different mineral admixtures and the adaptability of this cement with chemical admixtures are also discussed.In addittion,the existing problems of SMP and improvement measures are proposed.%硫铝酸钙改性硅酸盐水泥熟料兼具硅酸盐水泥熟料和硫铝酸盐水泥熟料的优良性能,同时该种水泥熟料对粉煤灰等火山灰类材料具有超强的活性激发效果,这使得硫铝酸钙改性硅酸盐水泥具有广阔的应用前景。主要概括了硫铝酸盐改性硅酸盐水泥的性能及水化特性,综述了该种水泥与不同矿物掺合料的复合性能以及与化学外加剂的适应性,提出了硫铝酸钙改性硅酸盐水泥存在的问题及改善措施。

  20. Influence of Metakaolin on Hydration Products of Portland Cement Pastes%偏高岭土对硅酸盐水泥水化产物的影响

    Institute of Scientific and Technical Information of China (English)

    丁卫清; 朱教群; 周卫兵; 孙正; 喻巍

    2014-01-01

    The content of hydration products calcium hydroxide,morphology,chemical composition and packing structure of C-S-H gel for portland cement pastes with different fraction of metakaolin were investigated by TG-DSC, AFM and SEM-EDAX.Effects of different dosages of metakaolin on characteristics of hydration products were also discussed.The results show that the content of hydration products calcium hydroxide was reduced by adding metaka-olin,from 18.68% to 13.66% when metakaolin content reaches 15% after 28 days.The particle size of C-S-H gel has been tended to become small with the increasing of metakaolin content,particles gather more closely.Metakaolin reacts with the hydration products Ca(OH)2 to produce C-S-H gel with lower molar ratio of CaO and SiO2 ,which has higher strength,better stability,the construction and chemical composition of C-S-H gel can be improved.%通过热重-差式扫描量热仪、原子力显微镜、扫描电子显微镜-能谱分析研究了偏高岭土对硅酸盐水泥水化产物Ca(OH)2的含量,C-S-H 凝胶的形貌特征、化学组成和堆聚结构的影响,讨论了水化产物性质随偏高岭土掺量变化的规律。结果表明:偏高岭土的掺入,水化产物Ca(OH)2的含量相应降低,在偏高岭土掺量15%时,水化28 d龄期试样中Ca(OH)2的质量分数由18.68%降低到13.66%;同时 C-S-H 凝胶颗粒尺寸随着偏高岭土掺量的增加而逐渐减小,堆聚更加紧密,偏高岭土与水泥水化产物Ca(OH)2反应生成结构致密稳定性更好的低Ca/Si值的 C-S-H 凝胶,改善了C-S-H 凝胶的结构和化学组成。

  1. Emissions of metals and polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs) from Portland cement manufacturing plants: inter-kiln variability and dependence on fuel-types.

    Science.gov (United States)

    Zemba, Stephen; Ames, Michael; Green, Laura; Botelho, Maria João; Gossman, David; Linkov, Igor; Palma-Oliveira, José

    2011-09-15

    Emissions from Portland cement manufacturing facilities may increase health risks in nearby populations and are thus subject to stringent regulations. Direct testing of pollutant concentrations in exhaust gases provides the best basis for assessing the extent of these risks. However, these tests (i) are often conducted under stressed, rather than typical, operating conditions, (ii) may be limited in number and duration, and (iii) may be influenced by specific fuel-types and attributes of individual kilns. We report here on the results of more than 150 emissions-tests conducted of two kilns at a Portland cement manufacturing plant in Portugal. The tests measured various regulated metals and polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs). Stack-gas concentrations of pollutants were found to be highly variable, with standard deviations on the order of mean values. Emission rates of many pollutants were higher when coal was used as the main kiln fuel (instead of petroleum coke). Use of various supplemental fuels, however, had little effect on stack emissions, and few statistically significant differences were observed when hazardous waste was included in the fuel mix. Significant differences in emissions for some pollutants were observed between the two kilns despite their similar designs and uses of similar fuels. All measured values were found to be within applicable regulatory limits.

  2. Avaliação preliminar do emprego de arenito zeolítico da região nordeste do Brasil como material pozolânico para cimento Portland Preliminary evaluation of sandstones from northeastern Brazil with pozzolanic properties for Portland cement

    Directory of Open Access Journals (Sweden)

    M. S. Picanço

    2011-12-01

    material. O arenito apresentou atividade pozolânica, sendo a estilbita responsável por este comportamento. Entretanto, a reatividade foi ligeiramente inferior ao mínimo exigido para ser empregado em escala industrial como pozolana. Estudos complementares são necessários para averiguar se o tratamento térmico entre 300 °C e 500 °C pode aumentar a atividade pozolânica do arenito devido a destruição da estrutura cristalina tanto da estilbita quanto da esmectita presente no arenito.Natural zeolites usually exhibit pozzolanic activity without any additional treatment, e.g. thermal activation. They have been used for building since the ancient Roman Empire times in the production of hydraulic cements and concretes. Nowadays, there are many discussions involving the natural zeolites pozzolanic reactivity in the incorporation of the Portland cement composition. The appropriate use of pozzolans enables the production of special cements with lower manufacturing cost and with a greater durability in comparison with the corresponding cements without addition. In Brazil, zeolite consumption comes either from the importation of foreign countries or synthetic products. No zeolite mine is available in the country and only few geological occurrences were already described in the literature without any commercial interest. In northeast Brazil, the Geological Survey (CPRM discovered zeolite-bearing sandstones related to Cretaceous sedimentary rocks of the Parnaíba Paleozoic Basin. The main purpose of this paper is to evaluate the possible use of such sandstones as pozzolan for using in Portland cements (CPI-S. A bulk sample of the zeolitic sandstone (AZ was collected in the field. In the laboratory, preparation included drying, milling and sieving at the following grain-size fractions, in order to remove quartz and concentrate the zeolite: 100# (AZ-1, 200# (AZ-2 and 325# (AZ-3. After mineralogical evaluation, the AZ-2 fraction was selected for further analysis and assays. The

  3. Key technology research on high strength low calcium Portland cement preparation%高强低钙硅酸盐水泥制备关键技术研究

    Institute of Scientific and Technical Information of China (English)

    刘松辉; 魏丽颖; 赵松海; 管学茂; 汪澜

    2014-01-01

    基于节能减排和应对气候变化的新要求,研究开发低钙水泥有多方面的重要意义。试验分别采用化学试剂和工业原料,运用化学分析、X-射线衍射、岩相分析等测试手段,初步探讨了高强低钙硅酸盐水泥制备关键技术。结果表明:工业原料中的微量元素能够解决高强低钙硅酸盐水泥的粉化问题;在试验设计的矿物组成和煅烧制度下,w(C2S)设计值在40%~45%,煅烧温度1400~1450℃时熟料性能最优。%Based on the new requirements of energy-saving emission reduction and climate change, research and development of low calcium cement has important meanings in many aspects. Using chemical reagent and industrial raw materials,by chemical analysis, X-ray diffraction and lithofacies analysis, key production technology of high-strength low-calcium Portland cement was discussed. The results show that the trace elements in industrial raw materials can solve the pulverization problem of high-strength low-calcium Port-land cement and in the system of mineral composition and calcination scheme, when w(C2S) design value is 40%~45%and firing tem-perature at 1400~1450℃, clinker performance will reach the best.

  4. in the Portland cement industry

    Directory of Open Access Journals (Sweden)

    José Pablo Paredes-Sánchez

    2015-01-01

    Full Text Available Este artículo describe una herra mienta de simulación bajo el en torno de Matlab®, que puede ser utilizada para estimar la auton omía de un vehículo con baterías o híbrido con pila de combustible y bater ías. El modelo es función de variables mecánicas y físicas que dependerán no solo del propio vehículo sino también del terreno. Su uso es extendido para recorridos obtenidos mediante dispositivos GPS y para ciclos estándar. Pueden obtenerse diferentes variables de salid a tales como: el consumo de hidrógeno y batería, el nivel hidró geno, el estado de carga de la batería, la potencia consumida, la producción de energía por parte de la pila, el máximo alcance del vehículo y el máximo número de ciclos finalizados. La simulación de rutas reales pro porciona una buena aproximación de la velocidad del vehículo pa ra usos, en lugar de utilizar ciclos de c onducción estándar, obteniendo así aproximaciones bas tante arbitrarias para una ruta real.

  5. PSD Determination, Portland Cement Plant

    Science.gov (United States)

    This document may be of assistance in applying the New Source Review (NSR) air permitting regulations including the Prevention of Significant Deterioration (PSD) requirements. This document is part of the NSR Policy and Guidance Database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

  6. Cements containing by-product gypsum

    Energy Technology Data Exchange (ETDEWEB)

    Bensted, J. [University of Greenwich, London (United Kingdom). School of Biological and Chemical Sciences

    1995-12-31

    Chemical by-product gypsum can readily replace natural gypsum in Portland cements and in blended cements like Portland pfa cement and Portland blast furnace cement without technical detriment in many instances. Indeed, sometimes the technical performance of the cement can be enhanced. The hydration chemistry is often changed, in that where there is at least some retardation of setting, more AFT phase (ettringite) is formed during early hydration at the expense of calcium silicate hydrates. By-product gypsum can also replace natural gypsum in speciality products like calcium aluminate cement-Portland cement mixes for producing quick setting cements and in calcium sulphoaluminate-type expansive cements. However, by-products gypsum have proved to be less successful for utilization in API Classes of oilwell cements, because of the greater difficulty in obtaining batch-to-batch consistency in properties like thickening time and slurry rheology. 11 refs., 3 figs., 5 tabs.

  7. Effect of hydrogen sulfide emissions on cement mortar specimens

    Energy Technology Data Exchange (ETDEWEB)

    Idriss, A. F. [Alberta Environment, Science and Technology Branch, Edmonton, AB (Canada); Negi, S. C.; Jofriet, J. C.; Haywoard, G. L. [Guelph Univ., Guelph, ON (Canada)

    2001-07-01

    Six different cement mortar specimens used in animal buildings, where they were exposed to hydrogen sulfide generated from anaerobic fermentation of manure during a period of one year, were investigated. Primary interest was on comparing the corrosion resistance of different cement mortar specimens under long term exposure to hydrogen sulfide. The impressed voltage technique was used to test the specimens in the laboratory. Results revealed that test specimens made with eight per cent silica fume cement replacement performed best and similar Portland cement mortar specimens with a water-cement ratio of 0.55 (PC55) the poorest. All other treatments, (Portland cement with a water to cement ratio of 045, Portland cement Type 50, Portland cement with fibre mesh and Portland cement Type 10 coated with linseed oil) all with water-cement ratios of 0.45, were less effective in preventing corrosion than silica fume replacement.

  8. Mineral resource of the month: hydraulic cement

    Science.gov (United States)

    van Oss, Hendrik G.

    2012-01-01

    Hydraulic cements are the binders in concrete and most mortars and stuccos. Concrete, particularly the reinforced variety, is the most versatile of all construction materials, and most of the hydraulic cement produced worldwide is portland cement or similar cements that have portland cement as a basis, such as blended cements and masonry cements. Cement typically makes up less than 15 percent of the concrete mix; most of the rest is aggregates. Not counting the weight of reinforcing media, 1 ton of cement will typically yield about 8 tons of concrete.

  9. Study on the preparation of high early strength slag Portland cement with high dosage of finely ground slag%用矿渣微粉配制高掺量早强矿渣水泥的研究

    Institute of Scientific and Technical Information of China (English)

    蒋永惠; 汪小东; 陈伟; 孙谋远; 王家军

    2001-01-01

    通过正交试验研究了不同细度、掺量的矿渣微粉和熟料对矿渣水泥性能的影响。试验发现,影响矿渣水泥 3d、 28d强度的主次因素不同, 3d强度主要受矿渣细度的影响, 28d强度则主要受矿渣掺量影响。采用分别粉磨后混合的生产工艺,用一定细度的矿渣微粉可以生产出掺量较高、早强性能好的矿渣水泥。%Effect of the fineness and dosage of finely ground slag and clinker on the performance of cement was studied through cross experiment. It was found that different factors exerted varying effect on the 3d and 28d strength of the slag cement, the 3d strength was mainly affected by the fineness of slag, while the 28d strength was dominated by the content of slag addition. The adoption of mixing after separate grinding process and the addition of finely ground slag with certain fineness can ensure the production of high early strength slag Portland cement with high dosage of finely ground slag.

  10. Evolución de la Porosidad de Pastas de Cemento Portland por la Incorporación de una Puzolana Natural Evolution of Porosity in Portland Cement Pastes by addition of Natural Pozzolan

    OpenAIRE

    J. L. Fernández; González, E.L.; Brown, S.A.; O.R. Batic

    2004-01-01

    Se ha determinado la evolución que se produce en la porosidad de las pastas elaboradas con cemento Portland para uso general (CPN IRAM 50000), al incorporarle una puzolana natural de la región, en distintas proporciones y en función del tiempo de curado. El ensayo de porosidad se realiza según Norma API-RP-40, basada en la ley de Boyle, por la cual se determina el volumen de los vacíos de las pastas. Este se determina por diferencia entre el volumen total del gas a una presión P1 de 6.9.10(5)...

  11. Fine natural aggregate replacement for sandy residue from itabirite exploitation in Portland cement mortar; Substituicao dos agregados miudos naturais por residuo arenoso gerado no beneficiamento do itabirito em argamassas de cimento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Melo, V.A.R. [Rede Tematica em Engenharia de Materiais (REDEMAT), MG (Brazil); Freire, C.B.; Pereira Junior, S.S.; Lameiras, F.S.; Tello, C.C.O., E-mail: cbf@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2011-07-01

    The fine natural aggregates are a material largely used by the civil construction for mortar and concrete production. Due to tightening legal restrictions imposed on their extraction, alternative materials are being considered. The use of sandy residue from BIF (banded iron formations) exploitation was investigated. It requires their grinding and flotation to concentrate iron oxides. Large amounts of sandy residue composed of quartz and iron oxides are generated in this process. The sandy residue was characterized relative to mineralogical composition, particle size distribution, presence of organic impurities, and particle shape. Mortar formulations were prepared by varying the type of cement, the cement to aggregate proportion and the water/cement ratio (a/c). The results of viscosity and density of fresh mortar, setting time, and compressive strength are presented. Compressive strength up to 19.5 MPa at 28 days were achieved with the use of cement CPV, a/c ratio of 0.80 and cement:aggregate proportion of 1:2. The results demonstrate the technical feasibility of using sandy residue as fine aggregate. (author)

  12. Evaluation of structural behaviour and corrosion resistant of austenitic AISI 304 and duplex AISI 2304 stainless steel reinforcements embedded in ordinary Portland cement mortars; Evaluacion del comportamiento estructural y de resistencia a la corrosion de armaduras de acero inoxidable austenitico AISI 304 y duplex AISI 2304 embebidas en morteros de cemento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Medina, E.; Cobo, A.; Bastidas, D. M.

    2012-07-01

    The mechanical and structural behaviour of two stainless steels reinforcements, with grades austenitic EN 1.4301 (AISI 304) and duplex EN 1.4362 (AISI 2304) have been studied, and compared with the conventional carbon steel B500SD rebar. The study was conducted at three levels: at rebar level, at section level and at structural element level. The different mechanical properties of stainless steel directly influence the behaviour at section level and structural element level. The study of the corrosion behaviour of the two stainless steels has been performed by electrochemical measurements, monitoring the corrosion potential and the lineal polarization resistance (LPR), of reinforcements embedded in ordinary Portland cement (OPC) mortar specimens contaminated with different amount of chloride over one year time exposure. Both stainless steels specimens embedded in OPC mortar remain in the passive state for all the chloride concentration range studied after one year exposure. (Author) 26 refs.

  13. CEMENT SLURRIES FOR GEOTHERMAL WELLS CEMENTING

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    1994-12-01

    Full Text Available During a well cementing special place belongs to the cement slurry design. To ensure the best quality of cementing, a thorough understanding of well parameters is essential, as well as behaviour of cement slurry (especially at high temperatures and application of proven cementing techniques. Many cement jobs fail because of bad job planning. Well cementing without regarding what should be accomplished, can lead to well problems (channels in the cement, unwanted water, gas or fluid production, pipe corrosion and expensive well repairs. Cementing temperature conditions are important because bot-tomhole circulating temperatures affect slurry thickening time, arheology, set time and compressive strength development. Knowing the actual temperature which cement encounters during placement allows the selection of proper cementing materials for a specific application. Slurry design is affected by well depth, bottom hole circulating temperature and static temperature, type or drilling fluid, slurry density, pumping time, quality of mix water, fluid loss control, flow regime, settling and free water, quality of cement, dry or liquid additives, strength development, and quality of the lab cement testing and equipment. Most Portland cements and Class J cement have shown suitable performances in geot-hermal wells. Cement system designs for geothermal wells differ from those for conventional high temperature oil and gas wells in the exclusive use of silica flour instead of silica sand, and the avoidance of fly ash as an extender. In this paper, Portland cement behaviour at high temperatures is described. Cement slurry and set cement properties are also described. Published in literature, the composition of cement slurries which were tested in geothermal conditions and which obtained required compressive strength and water permeability are listed. As a case of our practice geothermal wells Velika Ciglena-1 and Velika Ciglena-la are described.

  14. Kinetic and morphological differentiation of ettringites in plain and blended Portland cements with metakaolin and the ASTM C 452-68 test. Part II: Morphological differentiation by SEM and XRD analysis

    Directory of Open Access Journals (Sweden)

    Talero, R.

    2009-03-01

    Full Text Available The same cementitious materials (OPCs, SRPCs and matekaolin, MK, the same blended cements and the same ASTM C 452-68 test than in Part I, were used. Other complementary determinations were: chemical analysis of cementing materials, SEM and XRD analysis of ettringites and specific properties of some cement tested and of their pastes.The experimental results have also demonstrated that when 7.0% SO3, equivalent to 15.05% of gypsum, was added to the M pozzolan-containing Portland cement and tested with the ASTM C 452-68 method, it was not found to behave aggressively but rather as “setting regulator ”, because the increase in mechanical strengths over time and setting times in these mixes were, therefore, similar to the pattern observed in any PC. However, when the gypsum content was raised to triple than that amount (21.0% SO3, it behaved aggressively. In both cases, logically, ettringite from both origins were involved in the resulting beneficial or adverse behavior.En esta Parte II se utilizaron los mismos materiales cementíceos (CPO, CPRS, y metakaolín, MK, los mismos cementos de mezcla y el mismo método de ensayo ASTM C 452-68 que en la Parte I. Otras determinaciones complementarias fueron: análisis químico de los materiales cementíceos, análisis por DRX y SEM de ettringitas y propiedades específicas de algunos cementos ensayados y de sus pastas.Los resultados experimentales obtenidos han demostrado también que, el 7.0% de SO3 presente en los 30 cementos de mezcla con MK, ensayados conforme el método ASTM C 452-68, no se comporta como agresivo sino como ”regulador de fraguado”, porque los tiempos de fraguado y el aumento de resistencias mecánicas fueron como los de cualquier CP. De aquí que algunos de esos cementos de mezcla puedan ser considerados “cementos hidráulicos expansivos”, el resto, no. Sin embargo, cuando la cantidad de yeso aportada fue el triple (21,0% SO3, se comportó como agresivo, motivo por el cual

  15. Influence of relation CaO/SiO{sub 2} mixtures of anhydrous cement and mineral additives on the formation of CSH and combat the retrogression; Influencia da relacao CaO/SiO{sub 2} de misturas anidras de cimento e aditivos minerais na formacao do C-S-H e no combate a retrogressao

    Energy Technology Data Exchange (ETDEWEB)

    Anjos, Marcos A.S. [Instituto Federal de Educacao, Ciencia e Tecnologia do Rio Grande do Norte (IFRN), Natal, RN (Brazil); Martinelli, Antonio E.; Melo, Dulce M.A.; Souza, Pablo P.D. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Renovato, Tiago

    2012-07-01

    Temperatures above de 110 deg C cause cracks in the cement placed on the annular, and lost of hydraulic insulation; this crack is occasioned by the phenomenon of retrogression of the compressive resistance due to the conversion of the hydrated calcium silicate in phases calcium-rich, caused by the high temperatures in the wells. This paper presents the results of an experimental study aimed to investigate the influence of the molar ratio of different mixtures CaO/SiO{sub 2} Portland cement (CP) and minerals additives in the formation of CSH and retrogression of cement slurries subjected to high temperature and pressure. For both cement slurries were formulated with the addition of sugarcane biomass waste, silica flour and metakaolin in different concentrations of additives. The results of compressive strength and XRD showed that the use of cement slurries with molar ratio CaO/SiO{sub 2} near one can minimize the effect of retrogression when pulps are subjected to temperatures of 280 deg C and 17.2 MPa. (author)

  16. Effect of temperature on the hydration process and strength development in blends of Portland cement and activated coal gangue or fly ash

    Institute of Scientific and Technical Information of China (English)

    Pei-ming WANG; Xian-ping LIU

    2011-01-01

    This paper describes the results of an investigation into the effect of the variation of curing temperatures between 0 and 60 ℃ on the hydration process,pore structure variation,and compressive strength development of activated coal gangue-cement blend (ACGC).Hardened ACGC pastes cured for hydration periods from 1 to 360 d were examined using the non-evaporable water method,thermal analysis,mercury intrusion porosimetry,and mechanical testing.To evaluate the specific effect of activated coal gangue (ACG) as a supplementary cementing material (SCM),a fly ash-cement blend (FAC) was used as a control.Results show that raising the curing temperature accelerates pozzolanic reactions involving the SCMs,increasing the degree of hydration of the cement blends,and hence increasing the rate of improvement in strength.The effect of curing temperature on FAC is greater than that on ACGC.The pore structure of the hardened cement paste is improved by increasing the curing temperature up to 40 ℃,but when the curing temperature reaches 60 ℃,the changing nature of the pore structure leads to a decrease in strength.The correlation between compressive strength and the degree of hydration and porosity is linear in nature.

  17. 有替代硅酸盐水泥熟料的生产的选择吗?(英文)%Are There Any Practical Alternatives to the Manufacture of Portland Cement Clinker?

    Institute of Scientific and Technical Information of China (English)

    Ellis GARTNER

    2012-01-01

    There is a continuing need to look for alternative hydraulic binders with lower associated CO2 emissions than conventional Portland clinker(PC) based cements.Several novel non-PC-based binder systems that are at various different stages of development are reviewed.Currently,most cement makers are trying to replace PC to as great an extent as possible with supplementary cementi-tious materials(SCMs) in order to reduce the carbon footprint of cements,but are reaching limits due to the low hydraulic reactivity of pozzolans.In favorable cases this may be compensated by activation with concentrated basic alkali metal solutions,e.g.in complex formulations lying in between "geopolymers" and lime-activated pozzolanic binders.But an alternative approach,using clinkers based on belite,calcium sulfoaluminate and calcium aluminoferrite,such as Lafarge′s Aether?,also shows promise,as such clinkers can be made in conventional cement kilns.In the longer term,binders based on raw materials with no fossil CO2 content,such as magnesium silicates,might allow cements to be manufactured with zero carbon footprints.However,proof of durability in service seems likely to be the rate-limiting step for the acceptance of all such alternative binders,and the binder′s ability to protect reinforcing steel from corrosion remains the most critical issue for many applications.%人们一直在寻找CO2排放量低的水硬性胶凝材料,用它替代传统的以硅酸盐水泥熟料(Portland clinker,PC)为主的水泥。介绍了几种处于不同发展时期的新型非PC基的胶凝材料体系。目前大多数水泥生产商都尽可能多地用辅助性胶凝材料替代硅酸盐水泥熟料。火山灰材料具有低的水硬活性,它可使用高浓度碱金属溶液来激发,得到介于"地聚合物"和石灰激发火山灰胶凝材料间的复合胶凝材料。较远期可以期待基于贝利特、硫铝酸钙和铁铝酸钙矿物组成的水泥

  18. Reducing cement's CO2 footprint

    Science.gov (United States)

    van Oss, Hendrik G.

    2011-01-01

    The manufacturing process for Portland cement causes high levels of greenhouse gas emissions. However, environmental impacts can be reduced by using more energy-efficient kilns and replacing fossil energy with alternative fuels. Although carbon capture and new cements with less CO2 emission are still in the experimental phase, all these innovations can help develop a cleaner cement industry.

  19. 偏高岭土对硅酸盐水泥浆体干燥收缩行为的影响及机理%Effect of Metakaolin on Drying Shrinkage Behaviour of Portland Cement Pastes and its Mechanism

    Institute of Scientific and Technical Information of China (English)

    罗旌旺; 卢都友; 许涛; 许仲梓

    2011-01-01

    In order to explore the mechanism of the effect of the metakaolin (MK) effect on the drying shrinkage of cementitious ma- terials, the drying shrinkage and mass loss of blended Portland cement pastes with various MK contents (0, 5%, 10%, 15%) and different maturities (precured in water for 3 d and 28 d, respectively), were investigated by drying at 20 ℃ and 55% relative humidity. The composition and microstructure of cement pastes were determined by thermal analysis and mercury intrusion porosimetry. The results show that the effect of MK on the drying shrinkage of cement pastes is closely related to the MK content and maturity of the pastes. The late-age drying shrinkage of cement pastes with different maturities decreased with the increase of MK contents. However, the effect on the early age drying shrinkage depended on the maturity of paste. The MK increased slightly the early age drying shrinkage of the paste pre-cured for 3 d, and decreased the early age shrinkage of the paste pre-cured for 28 d. The drying shrinkage of cement paste was proportional to its mass loss and the mechanism of water loss and its relation with the drying shrinkage varied. The decrease of drying shrinkage of blended cement paste with the MK was due to the result of less and slower evaporation of water in the MK blended cement paste with low porosity and refined pores structure by the micro-filler effect, nuclear effect and/or pozzolanic reaction of the MK.%为探究偏高岭土(metakaolin,MK)影响水泥基材料干燥收缩(干缩)机理,研究了不同MK掺量(0、5%、10%、15%)、不同成熟度(水中分别预养护3d和28d)硅酸盐水泥浆体在20℃、55%相对湿度下的干缩和质量损失行为,并采用综合热分析和压汞法研究了不同成熟度水泥浆体的组成和微观结构。结果表明:MK对浆体干燥收缩行为的影响与掺量和浆体成熟度密切相关;MK使不同成熟度水泥浆体长期(28

  20. Análise fluido-dinâmica do escoamento em ensaio de permeabilidade ao ar de argamassas preparadas com cimento Portland de alto-forno Fluid-dynamic analysis of the flow in air permeability measurement of mortars prepared with blast-slag furnace Portland cement

    Directory of Open Access Journals (Sweden)

    V. M. Pereira

    2008-06-01

    . These studies not only have evaluated the permeability of porous media, but also to analyze the behavior of the fluid during the flow. Being about to the cement based materials, the measuring of the permeability becomes basic so that the durability of these can be estimate, therefore is the permeability that controls the rate of ingression and movement of deleterious agents inside these materials. Thus, diverse methodologies and mathematical equations have been used to foresee the permeability of cementitious materials, however, some discrepancies and nonsense in the results have been found. Amongst the used methodologies to measure the permeability of porous media, one meets developed it by Thenoz, which it has demonstrated good results in cement based materials. Thus, this work aims at, by means of assay of permeability to air, carried through in accordance with the methodology of Thenoz, to evaluate the fluid-dynamic behavior of air during the assay of permeability in mortars. For this, mortars prepared with two types of Portland cement of blast furnace (CP IIE-32 and CP III - 32, two relations water/cement (0.5 and 0.6 and ages of 14 and 28 days were used. By means of the gotten results it was possible to observe that during the draining the compressibility of air can be ignored, the regimen of draining can be considered as to plate, demonstrating that the methodology proposal for Thenoz and used mathematical equations can result in coefficients of trustworthy air permeability, therefore phenomena and considerations that could influence in this type of flow can be neglected, in accordance with what it is considered by literature.

  1. Effect of Ba2+on microstructure of C-S-H in portland cement pastes at variable temperature regime%变温下 Ba2+对水泥浆体C-S-H微结构的影响

    Institute of Scientific and Technical Information of China (English)

    沈凡; 胡晨光; 赵明宇

    2014-01-01

    为从分子尺度优化C-S-H微结构提供理论依据,采用模拟大体积混凝土内部变温历程的养护制度,运用29 Si魔角旋转核磁共振(29 Si MAS NMR)结合去卷积技术,研究了变温条件下Ba(OH)2掺量为1.0%时对水泥浆体C-S-H微结构的影响规律。结果表明:在变温条件下掺加Ba(OH)2提高了水泥浆体中硅酸盐矿物水化程度,尤其在水化早期(3 d)时硅酸盐矿物水化程度增幅较大,进而使C-S-H结构中硅氧四面体二聚体数量增加,导致其C-S-H平均分子链长(MCL)显著低于纯水泥浆体,避免了纯水泥浆体在降温阶段出现C-S-H的MCL降低的现象。同时,掺加Ba(OH)2进一步降低了水泥浆体在变温过程下C-S-H中Al3+取代Si4+的程度。%In order to provide the theoretical basis for optimizing the microstructure of C -S -H at molecular scale,by simulating the variable temperature process in the interior of mass concrete and using the 29 Si Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR)combined with deconvolution technique,effect of 1.0% Ba(OH)2 on C-S-H microstructure in Portland cement pastes at variable temperature regime was in-vestigated.The results show that the hydration of silicate minerals in cement pastes is improved by mixing the Ba(OH)2 at variable temperature regime,especially at the early stage hydration(3 d).The amount of silicate tetrahedra dimers is increased,leading to the mean chain length (MCL)of C -S -H in cement pastes with Ba(OH)2 lower than that in pure cement pastes,avoiding the phenomenon of C-S-H MCL reduction in pure cement pastes at the cooling stage.Meanwhile,the degree of Al3+substituting for Si4+is further decreased by adding to Ba(OH)2 in cement pastes at variable temperature regime.

  2. STUDY OF EXPANSIVE REACTIONS IN MORTAR MADE OF PORTLAND CEMENT WITH RICE HUSK ASH (RHA = ESTUDO DE REAÇÕES EXPANSIVAS EM ARGAMASSAS DE CIMENTO PORTLAND COM CINZA DE CASCA DE ARROZ (CCA

    Directory of Open Access Journals (Sweden)

    Jorge Luis Akasaki

    2007-01-01

    Full Text Available Rice husk is an agroindustrial residue which, when adequately burned and ground, may become an important pozzolan to be added in mortars. One factor contributing to the feasibility of its use is that of the 10 million tons of rice produced annually in this country, two million tons of husk remain, which can produce about 400 thousand tons of ash - enough to supply the market for mortars, concrete andothers. This large amount of material has become an environmental problem because it is being discarded inappropriately. Seeking a viable use of rice husk ash in the civil construction, the present research studies the variation in mortar behavior with different levels of RHA (Rice Husk Ash. Prismatic specimens were used, measuring 25x25x285mm, moulded with 0% (reference, 5%, 10% and 25% RHA. The influence of the RHA’s was verified through the following tests: efficiency of pozzolanic materials in avoiding expansion and alkali-aggregate reaction. The result obtained in the expansion reduction test (NBR 12651 showed that RHA reduces considerably the expansion of mortars due to reaction with the alkalis in the cement(94.29%, with the minimum reduction required by the norm for a pozolan being 75%. Although the expansion values in the alkali-aggregate reaction test (ASTM C-1260 remained above the limit allowed to consider the material innocuous, RHA levels of 5% as well as 10% obtained better results (expanded less then the referenceline. = A casca de arroz é um resíduo agroindustrial que adequadamente queimada e moída, pode se tornar uma importante pozolana a ser adicionada em argamassas. Um fator que viabiliza o seu emprego, é que dos 10 milhões de toneladas de arroz que o país produz por ano, sobram dois milhões de toneladas de casca – que podem rendercerca de 400 mil toneladas de cinza, o suficiente para suprir o mercado de argamassas, concreto e outros. Esta grande quantidade de material produzido passa a se tornar um problema, porque

  3. Chromium content in human skin after in vitro application of ordinary cement and ferrous-sulphate-reduced cement

    DEFF Research Database (Denmark)

    Fullerton, A; Gammelgaard, Bente; Avnstorp, C

    1993-01-01

    The amount of chromium found in human skin after in vitro application of cement suspensions on full-thickness human skin in diffusion cells was investigated. Cement suspensions made from ordinary Portland cement or Portland cement with the chromate reduced with added ferrous sulphate were used....... The cement suspensions were either applied on the skin surface under occlusion for 48 h or applied repeatedly every 24 h for 96 h. No statistically significant difference in chromium content of skin layers between skin exposed to ordinary Portland cement, skin exposed to cement with added ferrous sulphate...... and unexposed skin was observed, despite a more permeable skin barrier at the alkaline pH of the cement suspensions, i.e., pH 12.5. Increased chromium levels in epidermis and dermis were seen when ordinary Portland cement was applied as a suspension with added sodium sulphate (20%) on the skin surface for 96 h...

  4. 粉煤灰对硅酸盐水泥-铝酸盐水泥-硬石膏体系性能的影响%Influence of fly ash on compressive strength with portland cement-aluminate cement-anhydrite system

    Institute of Scientific and Technical Information of China (English)

    李海南; 马保国; 张承志

    2014-01-01

    This paper studies the influence of amount of mixed fly ash (0 %, 10 %, 20 %, 30 %) on compressive strength with portland cement-aluminate cement-anhydrite system. Experimental results show that with the increase of fly ash, the compressive and transverse strength decreases; With the prolonging of curing age, the compressive and transverse strength decrease slowly.%研究了不同掺量的粉煤灰(0%,10%,20%,30%)对硅酸盐水泥-铝酸盐水泥-硬石膏三元复合体系力学性能的影响。试验结果表明:随着粉煤灰掺量的增加,该三元体系浆体的抗压、抗折强度均减小,但减小的程度不一致,与养护龄期有关。随着养护龄期的延长,砂浆抗压、抗折强度降低幅度减小。这可能是由于在浆体水化后期,粉煤灰的火山灰作用起了一定的作用。

  5. Chemical and mineralogical characterization of two commercial cements and its evolution in function of time; Caracterizacion quimica y mineralogica de dos cementos comerciales y su evolucion en funcion del tiempo

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez B, O.

    2014-07-01

    Mineralogical evolution of Portland cement is studied during hydration process using materials characterization techniques as X-ray diffraction (XRD) and scanning electron microscopy (Sem) in order to analyze the changes in the various cement minerals as alite, belite, celite, during processing to the hydrated phases of tobermorite gel, portlandite and ettringite, respectively, in the cement paste setting at different ages (3, 7 and 28 days). It was found that the hydration process occurs differently in each mineral because of their reaction rates or changes they experience in their crystals during processing of anhydrous to hydrated phase. You may notice changes in the appearance of the dough as you go hydration and the formation of tobermorite gel, portlandite and ettringite. (Author)

  6. Effect on dispersion and reinforcement of CaCO 3 whisker-reinforced Portland cement caused by mechanical grinding method%机械粉磨对碳酸钙晶须在硅酸盐水泥中的分散性及增强效果的影响

    Institute of Scientific and Technical Information of China (English)

    张聪; 曹明莉; 姜道旭; 李昂

    2014-01-01

    碳酸钙晶须对硅酸盐水泥的增强效果已经得到了证实,但是同时存在着晶须团聚以及晶须与水泥基质界面黏结强度较弱等问题。试图采用机械粉磨手段,尝试解决碳酸钙晶须在硅酸盐水泥中的分散性问题,并通过分析试验结果,对碳酸钙晶须增强硅酸盐水泥的机理进行了讨论。%The positive effect of CaCO3 whisker-reinforced Portland cement has been confirmed,however,it still has some issues needed to solve,e.g.,aggragation of whisker and the interfacial bonding strength between whisker and cement need to be increased ,and so on.And the object is aiming at solving the issue of dispersion by mechanical grinding method.At the same time ,this paper discussed the toughening mechanisms of whisker-reinforced Portland cement composite based on the analysis of the test results.

  7. Un nuevo método de diseño de losas para pisos industriales ante la inaplicabilidad de los métodos simplificados de diseño, entre ellos los de la portland cement association (pca) y wire reinforcement institute (wri)

    OpenAIRE

    Camero Sanabrial, Hugo Ernesto

    2010-01-01

    Se presenta una metodología para el diseño de losas sobre terreno para pisos industriales en donde hay excentricidad entre el centroide de la losa y el centro de gravedad de las cargas del ele cargado del montacargas que transita sobre el piso. Mediante un ejemplo se analiza cómo los métodos de diseño de pisos de la Portland Cement Association (PCA) y la Wire Reinforcement Institute (WRI) son inadecuados para el diseño de pisos sometidos a esta condición. El nuevo método propuesto para diseña...

  8. PERFORMANCE OF PULVERIZED SLAG-SUBSTITUTED CEMENT

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The Portland cement is equivalently substituted by slag micropowders with various specific areas. The workability,activity and acid-corrosion resistance of the slag-substituted cements are investigated,the activation of gypsum is discussed,also the porosity and pore distribution of mortars of the slag micropowders cement are determined by mercury intrusion porosimetry.

  9. 硅酸盐水泥在模拟体液中降解和矿化性能%Degradability and biomineralization ability of Portland cement in simulated body fluid

    Institute of Scientific and Technical Information of China (English)

    陈耀忠; 吕晓迎; 刘根娣

    2014-01-01

    To investigate the degradability and biomineralization ability of Portland cement (PC ), samples of PC were immersed in simulated body fluid (SBF)for 3,7 and 14 d respectively.X-ray diffraction (XRD),a Fourier transform infrared spectrophotometer (FTIR)and a scanning electron microscope (SEM)were used to investigate the biomineralization ability of PC;meanwhile,the weight loss of the samples and the pH value changes of their immersion media were monitored.The results show that with the soaking time prolonged,the weight of PC increases.The immersion media has a high alkalinity in the first three days,and then,the pH value declines.The XRD and FTIR patterns and the SEM images show that in SBF for 3 days,calcium carbonate is formed on the sur-face of PC and for 7 days carbonated hydroxyapatite is formed.Therefore,PC displays good biomin-eralization ability in SBF.%为了检测硅酸盐水泥(PC)在模拟体液(SBF)中降解和生物矿化性能,将硅酸盐水泥样品分别浸泡于模拟体液3,7及14 d后,采用X射线衍射仪(XRD)、傅里叶红外光谱(FTIR)及扫描电镜(SEM)等方法研究其生物矿化性能;并同时检测其失重率及模拟体液浸泡液的pH值变化情况.研究结果发现:随着浸泡时间的增长,硅酸盐水泥的质量增加;模拟体液在浸泡前3d碱性较强,随后其pH值逐渐降低.X射线衍射、红外光谱图谱及扫描电镜图像表明:硅酸盐水泥浸泡3d后,在其表面有碳酸钙生成;浸泡7d后,其表面有碳酸羟基磷灰石生成.因此,硅酸盐水泥具有良好的生物矿化能力.

  10. 水化普通硅酸盐水泥吸附水中氟化物的动力学与热力学解析%Kinetic and Thermodynamic Analysis of Fluoride Adsorption to Hydrated Portland Cement

    Institute of Scientific and Technical Information of China (English)

    曹艳; 任勇翔; 黄廷林; 张宏伟; 孙艳君

    2012-01-01

    The kinetic and thermodynamic processes of fluoride adsorption to hydrated Portland cement (HPC) were studied. The results indicated that the adsorption equilibrium was reached in 192 h, and the adsorption capacities were 14. 63 mg/g at 20 ℃ and 13. 14 mg/g at 4 ℃. Kinetic data were well described by the pseudo-second-order model, and the adsorption rate was controlled by the intra-particle diffusion. The fluoride adsorption behavior of the particles of HPC was appropriately fitted to the Langmuir isotherm. The adsorption enthalpy change of 16. 56 kJ/mol indicated that the adsorption process was mainly a chemical adsorption, and the adsorption was an endothermic reaction. The positive entropy change meant that the randomness was increased at the solid/solution interface during the adsorption of fluoride onto HPC. The adsorption of fluoride to HPC was a spontaneous process, since the changes of adsorption Gibbs free energy were negative at both 4 and 20 X.. The results of the desorption study and XRD analysis also suggested that the process of fluoride adsorption by HPC was mainly a chemical adsorption.%以水化普通硅酸盐水泥颗粒为除氟吸附剂,对其吸附水中氟化物的动力学和热力学过程进行了解析.结果表明:水化普通硅酸盐水泥对氟化物的吸附平衡时间为192 h,20℃时其吸附容量为14.63 mg/g,4℃时为13.14 mg/g.吸附速率特性与准二级动力学模型拟合性较好且吸附速率由颗粒内部扩散速率控制,吸附行为均满足Langmuir吸附等温式.吸附焓变为16.56 kJ/mol,表明该吸附过程是以化学吸附为主的吸热反应;吸附熵变为正值,说明该吸附过程是熵推动为主的过程;吉布斯自由能在4和20℃时均为负值,说明该吸附反应是一个自发过程.脱附研究与XRD分析结果也证实,该吸附反应以化学吸附过程为主.

  11. Study on the Performance of Energy Saving Facade Materials Containing Lime Mud, Lithium Slag and Portland Cement%利用造纸白泥及锂盐尾渣制备轻质保温墙体材料

    Institute of Scientific and Technical Information of China (English)

    刘来宝; 唐凯靖; 刘德平; 王忠祥

    2012-01-01

    本实验将未经预处理含水40%左右的造纸白泥,通过复配适量的分散剂、促凝早强剂及表面活性剂等外加剂后,经80℃、12h蒸汽养护,制备了不同容重的“造纸白泥-锂渣-水泥复合发泡保温墙体材料”及对应的基体,并测试了其力学性能与热工性能.结果表明:白泥掺量达50%的复合基体,3d抗压强度可达24.1 MPa,测试结果重现性好;残碱固化效果较佳,加速测试结果未有泛霜.同容重条件下,造纸白泥和锂渣的掺入没有显著改变该体系的力学性能与保温性能,掺20%锂渣样品的28d抗压强度高于对比样;容重为600 kg/m3时,二者各掺30%样品的导热系数低至0.08 W/(m· K).%The energy saving facade materials containing lime mud, lithium slag and portland cement were prepared with different bulk density, which using the lime mud that without pretreatment and adding admixture. Its mechanical and thermal properties were tested after steam curing at 80 X? To 12 h. The results show that the compressive strength of composite cementitious system containing 50% lime mud is up to 24.1 Mpa when hydrated for 3 days. The frost did not appear when the testing was accelerated. Mechanical properties and thermal conductivity of the system did not significantly change when bulk density was under the same conditions, the compressive strength of the system contained 20 % lithium was better than comparison sample; the thermal conductivity was 0.08 W/(mK) when contained 30% lime mud and 30% lithium at 600 kg/m3.

  12. Lunar cement

    Science.gov (United States)

    Agosto, William N.

    1992-01-01

    With the exception of water, the major oxide constituents of terrestrial cements are present at all nine lunar sites from which samples have been returned. However, with the exception of relatively rare cristobalite, the lunar oxides are not present as individual phases but are combined in silicates and in mixed oxides. Lime (CaO) is most abundant on the Moon in the plagioclase (CaAl2Si2O8) of highland anorthosites. It may be possible to enrich the lime content of anorthite to levels like those of Portland cement by pyrolyzing it with lunar-derived phosphate. The phosphate consumed in such a reaction can be regenerated by reacting the phosphorus product with lunar augite pyroxenes at elevated temperatures. Other possible sources of lunar phosphate and other oxides are discussed.

  13. Efeito da aplicação do poliestireno sulfonado (PSSNa como aditivo em argamassas e concretos de cimento Portland CPV32 Effect of PSSNa as admixture in mortars and concrete of cement portand CPV32

    Directory of Open Access Journals (Sweden)

    Betina Royer

    2005-03-01

    Full Text Available Neste trabalho foi investigado o uso do Poliestireno sulfonado (PSSNa, produzido a partir de copos plásticos descartáveis de Poliestireno (PS, como aditivo em argamassas e concretos de cimento Portland CPV32. A avaliação do PSSNa como aditivo foi baseada em ensaios de fluidez e resistência mecânica à compressão de corpos de prova. Foi observado, em argamassas com relação água/cimento (a/c de 0,48, um aumento na fluidez com o aumento das porcentagens de PSSNa (0,25 a 1,00%. A adsorção do PSSNa sobre as partículas de cimento melhora a dispersão dos componentes da argamassa, aumentando a resistência mecânica à compressão dos corpos de prova após a cura. A aplicação do PSSNa em concreto apresentou o mesmo efeito. O abatimento do concreto sem PSSNa foi de 50 mm, atingindo cerca de 200 mm com o uso do polieletrólito. Devido à elevada plasticização observada é possível empregar o PSSNa como aditivo redutor de água. Foi produzido um concreto com o mesmo abatimento da referência sem aditivo reduzindo-se a quantidade de água em 20,8%. O ganho de resistência mecânica à compressão obtido foi de 21,5 e 26,3 %, respectivamente aos 7 e 28 dias de cura. Estes resultados mostraram que soluções de PSSNa podem atuar eficientemente como aditivo superplastificante ou redutor de água em argamassas e concretos.In this work an investigation was made of the effects from adding PSSNa, obtained from disposable polystyrene (PS cups, as admixture agent in mortars and concrete with varying ratios from 0.25 to 1.00%. The evaluation of PSSNa as additive was based on results of fluidity and mechanical strength to compression. In mortars with water/cement ratio of 0.48, an increase in flow was observed when the dosage of PSSNa varied from 0.25 to 1.00%. The dispersion of mortar components was improved due to the adsorption of PSSNa on cement particles, which increased the mechanical strength of mortars. Similar results were obtained with the

  14. Freezing resistance of high iron phoasphoaluminate cement

    Science.gov (United States)

    Zhang, S. X.; Lu, L. C.; Wang, S. D.; Zhao, P. Q.; Gong, C. C.

    2017-03-01

    The influence of freeze-thaw cycle on the mechanical properties of high iron phoasphoaluminate cement was investigated in the present study. The visual examination was conducted to evaluate the surface damage. The deterioration considering the weight loss, modulus loss of relative dynamic elastic and strength loss of mortar were also investigated. The morphology of hydration products were analysed by SEM. Compared with ordinary Portland cement and sulphoaluminate cement, the frost resistance of high iron phosphoraluminate cement is better. Hydration products of high iron phoasphoaluminate cement contain sheet crystals, and a lot of gel form a dense three-dimensional network structure, which results in a lower porosity. Different from ordinary Portland cement, the hydration product of high iron phoasphoaluminate cement does not contain Ca(OH)2, and low alkalinity reduces its osmotic pressure. The lower porosity and osmotic pressure are the two main reasons which causes in the higher frost resistance of high iron phoasphoaluminate cement.

  15. Effects of Thaumasite Formation on the Performance of Portland-limestone Concrete Stored in Magnesium Sulfate Solution

    Institute of Scientific and Technical Information of China (English)

    GAO Lixiong; YAO Yan; WANG Ling

    2005-01-01

    The influence of thaumasite formation on the performance of Portland- limestone cement concrete stored in magnesium sulfate solution was studied. The experimental results show that the deterioration of Portlandlimestone cement concrete is higher than that of Portland cement concrete. The more the content of limestone, the more serious the deterioration of concrete, and also the lower the temperature, the earlier the deterioration of concrete. Thaumasite was detected to form in the Portland-limestone pastes when stored in 10wt% MgSO4 solution at 3- 10 ℃ and it was easy to form at lower temperatures.

  16. Advances in understanding hydration of Portland cement

    Energy Technology Data Exchange (ETDEWEB)

    Scrivener, Karen L., E-mail: Karen.scrivener@epfl.ch [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, 1015 (Switzerland); Juilland, Patrick [Sika Technology AG, Zürich (Switzerland); Monteiro, Paulo J.M. [Department of Civil and Environmental Engineering, University of California at Berkeley (United States)

    2015-12-15

    Progress in understanding hydration is summarized. Evidence supports the geochemistry dissolution theory as an explanation for the induction period, in preference to the inhibiting layer theory. The growth of C–S–H is the principal factor controlling the main heat evolution peak. Electron microscopy indicates that C–S–H “needles” grow from the surface of grains. At the peak, the surface is covered, but deceleration cannot be attributed to diffusion control. The shoulder peak comes from renewed reaction of C{sub 3}A after depletion of sulfate in solution, but release of sulfate absorbed on C–S–H means that ettringite continues to form. After several days space becomes the major factor controlling hydration. The use of new analytical technique is improving our knowledge of the action of superplasticizers and leading to the design of molecules for different applications. Atomistic modeling is becoming a topic of increasing interest. Recent publications in this area are reviewed.

  17. Portland cement hydration: study of various techniques

    Directory of Open Access Journals (Sweden)

    Triviño Vázquez, F.

    1974-06-01

    Full Text Available Not availableLa complejidad de la química del cemento es motivo de que aún hoy día permanezcan sin aclarar muchos procesos que transcurren durante el fraguado y posterior endurecimiento de la pasta. La industria de la construcción precisa de un conocimiento técnico más sólido, ya que al saber el modo de actuar de los componentes de la pasta del cemento puede conseguir de este material: facilidad y economía en su empleo, resistencias mecánicas elevadas e inalterabilidad y duración en las obras realizadas. Cualquier nuevo conocimiento sobre la química de la pasta, por ello, suele tener inmediata aplicación o sirve como base para ulteriores investigaciones, que en su día darán nuevas propiedades prácticas al cemento o incluso a otros materiales diferentes. El comportamiento de la pasta durante las primeras 24 horas ha sido el motivo de este estudio. Se efectuaron medidas térmicas, de conductividad, de contenidos de productos solubles en agua, de productos cristalinos y de variaciones de solicitación de agua, por los métodos que veremos a continuación.

  18. Microstructure Analysis of Heated Portland Cement Paste

    NARCIS (Netherlands)

    Zhang, Q.; Ye, G.

    2011-01-01

    When a concrete structure is exposed to high temperature, the mechanical damage and chemical transformation take place simultaneously, which will change the microstructure of material. On the other hand, the mechanical properties and transport properties depend on the development of microstructure o

  19. El cemento portland blanco

    Directory of Open Access Journals (Sweden)

    Rimathé, W.

    1959-12-01

    Full Text Available Not availableEn un artículo precedente, el autor expuso los resultados de los ensayos hechos oficialmente con el cemento CBR extrablanco. El cemento blanco está químicamente emparentado con el cemento portland. En una tabla da el autor la composición química del cemento blanco producido en diferentes paises, en comparación con la del cemento portland.

  20. Activation of Anhydrate Phosphogypsmn by K2SO4 and Hemihydrate Gypsum

    Institute of Scientific and Technical Information of China (English)

    YANG Min; QIAN Jueshi

    2011-01-01

    Lime pretreated phosphogypsum(PG) was calcined at 500 ℃ to produce anhydrate gypsum cement.Due to the slow hydration of anhydrate gypsum,additives,K2SO4 and hemihydrate gypsum were selected to accelerate the hydration of anhydrate.The hydration characteristics,the resistance to hydrodynamic water,and the mineralogical studies were investigated.The experimental results suggest that activated by K2SO4 and hemihydrate,anhydrate PG hydrates much more rapidly than that in the presence of only K2SO4 or in the absence of additives.The binder has proper setting time,good strength development,and relatively better resistance to water.The hardened binder has hydrated products of rod or stick like shaped dihydrate gypsum crystals.

  1. Hydration Characteristics of Metakaolin Admixtured Cement using DTA, XRD and SEM Techniques

    Science.gov (United States)

    Govindarajan, D.; Gopalakrishnan, R.

    2008-04-01

    The paper aims to investigate hydration and pozzolanic reaction in Portland cement paste with different replacement percentages (0%, 10%, 20% and 30%) of metakaolin. The compressive strength of the metakaolin admixtured cement was measured at 1 day, 1 week and 4 weeks. The compressive strength developments of the metakaolin admixtured cement are compared with Portland cement. It is found that metakaolin contributes significantly to strength development as an accelerating admixture for Portland cement. The pozzolanic reactions and the reaction products were determined by DTA, XRD and SEM.

  2. Some durability aspects of hybrid alkaline cements

    Directory of Open Access Journals (Sweden)

    Donatello S.

    2014-04-01

    Full Text Available Blended cements that contain a high content of fly ash and a low content of Portland cement typically suffer from low early strength development and long setting times. Recently, one method of overcoming these problems has been to use an alkali activator to enhance the reactivity of fly ash particles at early ages. Such cements can be grouped under the generic term “hybrid alkaline cements”, where both cement clinker and fly ash, encouraged by the presence of alkalis, are expected to contribute to cementitious gel formation. The work presented here examines some of the durability aspects of high fly ash content hybrid alkaline cement. Specifically, the aspects investigated were: exposure at high temperatures (up to 1000°C, resistance to immersion in aggressive solutions and susceptibility to the alkali aggregate reaction. All tests were repeated with a commercially available sulfate resistant Portland cement for comparison. When exposed to high temperatures, the hybrid alkaline cement showed strikingly different behaviour compared to the control Portland cement, showing fewer micro-cracks and maintaining residual compressive strengths at least equal to original strengths. Beyond 700°C, the hybrid alkaline cement began to sinter, which resulted in shrinkage of around 5% and a 100% increase in residual compressive strengths. No such sintering event was noted in the control Portland cement, which showed a drastic loss in residual compressive strengths upon heating. In immersion tests, the hybrid alkaline cement possessed excellent resistance to sulfate and seawater attack, similar to the control sulfate resistant cement. Both cements were however severely degraded by immersion in 0.1M HCl for 90 days. Both binders complied with the accelerated alkali-aggregate test but when this test was extended, the hybrid alkaline binder showed much greater dimensional stability. Possible reasons for the differences in durability behaviour in both cements

  3. Carbonated deep in non-NBR 9831/2006 Portland cements in oil well; Carbonatacao em cimentos nao especificados pela Norma NBR 9831/2006 quando empregados em pocos de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Hastenpflug, D.; Moraes, M.K.; Dalla Vecchia, F.; Costa, E.M. [Pontificia Univ. Catolica do Rio Grande do Sul (PUC-RS), Porto Alegre, RS (Brazil). Centro de Excelencia em Pesquisa sobre Armazenamento de Carbono (CEPAC); Pontificia Univ. Catolica do Rio Grande do Sul (PUC-RS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia e Tecnologia de Materiais (PGETEMA)], Email: hasten@gmail.com; Abreu, J.V. [Holcim Brasil S.A., Sao Paulo, SP (Brazil). Centro Tecnologico

    2010-07-01

    The NBR 9831/2006 well cements are indicated to well completions to sequestration of CO{sub 2} in geologic formations, being cement class G the most popular. However, studies have shown that Class G cement might suffers considerable degradation due to exposure to CO{sub 2} under geologic sequestration conditions. In order to increase cement resistance to acid attack, admixtures and additives as fly ash, fume, limestone and mineral wastes have been investigated. In this paper experiments were conducted to evaluated four commercial non- NBR 9831/2006 cements generally used in pavement area, in cracks completion and in concretes for use in aggressive environments. These cements were chosen because they have mineral additive into their specifications. This paper analyses the carbonated deep after accelerated carbonation reaction tests that simulate the well's geological conditions, when exposed to water saturated with supercritical CO{sub 2} and wet supercritical CO{sub 2} at 70 deg C and 15 MPa, during 7 days. In addition, compressive strength and the workability of these pastes were evaluated. The results were compared to the ones realized at the same condition with cement class G. It was observed that the cement used in pavement area (Pavifort) has a good resistance to CO{sub 2} attack when compared to the other types of cement, but its compressive strength is very low. (author)

  4. Prediction of chloride ingress and binding in cement paste

    DEFF Research Database (Denmark)

    Geiker, Mette Rica; Nielsen, Erik Pram; Herforth, Duncan

    2007-01-01

    This paper summarizes recent work on an analytical model for predicting the ingress rate of chlorides in cement-based materials. An integral part of this is a thermodynamic model for predicting the phase equilibria in hydrated Portland cement. The model’s ability to predict chloride binding...... in Portland cement pastes at any content of chloride, alkalis, sulfates and carbonate was verified experimentally and found to be equally valid when applied to other data in the literature. The thermodynamic model for predicting the phase equilibria in hydrated Portland cement was introduced into an existing...... Finite Difference Model for the ingress of chlorides into concrete which takes into account its multi-component nature. The “composite theory” was then used to predict the diffusivity of each ion based on the phase assemblage present in the hydrated Portland cement paste. Agreement was found between...

  5. Phosphate based oil well cements

    Science.gov (United States)

    Natarajan, Ramkumar

    The main application of the cement in an oil well is to stabilize the steel casing in the borehole and protect it from corrosion. The cement is pumped through the borehole and is pushed upwards through the annulus between the casing and the formation. The cement will be exposed to temperature and pressure gradients of the borehole. Modified Portland cement that is being used presently has several shortcomings for borehole sealant. The setting of the Portland cement in permafrost regions is poor because the water in it will freeze even before the cement sets and because of high porosity and calcium oxide, a major ingredient it gets easily affected by the down hole gases such as carbon dioxide. The concept of phosphate bonded cements was born out of considerable work at Argonne National Laboratory (ANL) on their use in stabilization of radioactive and hazardous wastes. Novel cements were synthesized by an acid base reaction between a metal oxide and acid phosphate solution. The major objective of this research is to develop phosphate based oil well cements. We have used thermodynamics along with solution chemistry principles to select calcined magnesium oxide as candidate metal oxide for temperatures up to 200°F (93.3°C) and alumina for temperatures greater than 200°F (93.3°C). Solution chemistry helped us in selecting mono potassium phosphate as the acid component for temperatures less than 200°F (93.3°C) and phosphoric acid solution greater than 200°F (93.3°C). These phosphate cements have performance superior to common Portland well cements in providing suitable thickening time, better mechanical and physical properties.

  6. Basic Chemistry for the Cement Industry.

    Science.gov (United States)

    Turner, Mason

    This combined student workbook and instructor's guide contains nine units for inplant classes on basic chemistry for employees in the cement industry. The nine units cover the following topics: chemical basics; measurement; history of cement; atoms; bonding and chemical formulas; solids, liquids, and gases; chemistry of Portland cement…

  7. Copper Slag Blended Cement: An Environmental Sustainable Approach for Cement Industry in India

    Directory of Open Access Journals (Sweden)

    Jagmeet Singh

    2016-04-01

    Full Text Available Indian cement industry is facing environmental issue of emission of carbon dioxide (CO2, a greenhouse gas. Blended cements including supplementary cementitious materials are substitute of Portland cement to reduce CO2 emission. The present paper investigates theappropriateness of copper slag (CS as supplementary cementitious material. Strength properties and hydration of mixes were determined at different replacement levels of CS with cement. Compressive, flexural and tensile strength of each mix was found out at different curing periods. The hydration of cement was investigated through X-ray diffraction (XRD. The strength test results showed that substitution of up to 20% of CS can significantly replace Portland cement.XRD test results were corresponding to strength test results. The present study encourages the utilization of CS as supplementary cementitious material to make economical and environmentally sustainable blended cement

  8. Study of the action of phosphate ions contained in the mixing water on the hydration of a Portland cement; Etude de l'action des phosphates presents dans l'eau de gachage sur l'hydratation d'un ciment Portland

    Energy Technology Data Exchange (ETDEWEB)

    Benard, Ph

    2005-12-15

    Cementation is considered as the most attractive solution for the conditioning of low and intermediate radioactive wastes. The species contained in these wastes can strongly influence the reactivity of the cement pastes, it is in particular the case of the ortho-phosphate ions which are found in the evaporation concentrates. The aim of our work was to determine the influence of these ions on the hydration and the rheological properties of the cement pastes at early age as well as the mechanical and physical properties on the hardened material. (author)

  9. Addition of polyurethane dispersions to Portland G for oil wells steam injection submitted to vapor injection; Adicao de poliuretana em dispersao a Portland G para cimentacao de pocos de petroleo sujeitos a injecao de vapor

    Energy Technology Data Exchange (ETDEWEB)

    Silva, L.B. da; Lima, F.M. de; Martinelli, A.M.; Bezerra, U.T.; Mello, D.M.A. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Araujo, R.G.S. [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2004-07-01

    Portland cement is by far the most important binding material used in oil well cementing. The cement sheath is responsible for both the mechanical stability of the wellbore and zonal isolation. During primary cementing and the production lifespan of the well, the cement sheath is exposed to adverse thermo-mechanical conditions, which may crack the intrinsically brittle cement material. Cracking affects the mechanical integrity of the sheath resulting in the contamination of oil or gas pay zones, as well as in the increase of producing costs related to the extraction of pebble and water. This scenario is especially encountered in wells containing heavy oils, typical of the Northeastern region of Brazil. The objective of the present study was to improve the fracture toughness of hardened Special Portland Cement slurries by the addition of aqueous polyurethane to Portland-based slurries used in primary cementing, plug backs and squeeze operations, improving environmental and economical impacts. The results revealed that the addition of polyurethane increased the viscosity of the slurry but still within the limits established by oil well cement guidelines. No significant increase was observed in the compressive strength of the cement. However, the addition of polyurethane improved the toughness of the cement increasing its ability to withstand thermo-mechanical cycles typical of heavy oil recovery. In addition, significant reduction in permeability was observed as the contents of polyurethane increased, contributing to the reduction in set time and gas migration through the cement sheath. (author)

  10. Isothermal Calorimetry Study of Blended Cements and its Application in Numerical Simulations

    NARCIS (Netherlands)

    Xiong, X.; Van Breugel, K.

    2001-01-01

    Apparent activation energy (E) is generally used to consider the effect of temperature on the kinetics of cement hydration in the numerical simulation of cement hydration processes. This paper deals with an experimental study on the kinetics of Portland cement and blast furnace slag cement using iso

  11. 40 CFR 427.20 - Applicability; description of the asbestos-cement sheet subcategory.

    Science.gov (United States)

    2010-07-01

    ... asbestos-cement sheet subcategory. 427.20 Section 427.20 Protection of Environment ENVIRONMENTAL PROTECTION... Asbestos-Cement Sheet Subcategory § 427.20 Applicability; description of the asbestos-cement sheet... asbestos, Portland cement, silica, and other ingredients are used in the manufacturing of...

  12. 40 CFR 427.10 - Applicability; description of the asbestos-cement pipe subcategory.

    Science.gov (United States)

    2010-07-01

    ... asbestos-cement pipe subcategory. 427.10 Section 427.10 Protection of Environment ENVIRONMENTAL PROTECTION... Asbestos-Cement Pipe Subcategory § 427.10 Applicability; description of the asbestos-cement pipe... asbestos. Portland cement, silica and other ingredients are used in the manufacturing of...

  13. Formulating a low-alkalinity cement for radioactive waste repositories

    Energy Technology Data Exchange (ETDEWEB)

    Coumes, C. Cau Dit; Courtois, S.; Leclercq, S.; Bourbon, X

    2004-07-01

    A multi-annual research program has been launched in January 2003 by CEA, EDF and ANDRA in order to formulate and characterize low-alkalinity and low-heat cements which would be compatible with an underground waste repository environment. Four types of bindings have been investigated: binary blends of Portland cement and silica fume or metakaolin, as well as ternary blends of Portland cement, fly ash and silica fume or metakaolin. Promising results have been obtained with a mixture comprising 37.5% Portland cement, 32.5% silica fume, and 30% fly ash: pH of water in equilibrium with fully hydrated cement is below 11. Moreover, silica fume compensates for the low reactivity of fly ash, while fly ash allows to reduce water demand, heat release, and dimensional variations of cement pastes and mortars. (authors)

  14. Sulfatos en el cemento portland y su incidencia sobre el falso fraguado: Estado actual del conocimiento

    Directory of Open Access Journals (Sweden)

    de la Cruz, Ignacio

    1983-12-01

    Full Text Available A bibliographical study is carried out of the sulphates which may be present in the clinker and Portland cement, as likewise the effects of the aeration and temperature on the setting. This work is a prior phase of a wide experimental investigation carried out in the IETCC, on anomalies or setting and phenomena of "lumping" in Portland cement.

    Se realiza un estudio bibliográfico de los sulfatos que pueden estar presentes en el clínker y cemento portland, así como de los efectos de la aireación y temperatura sobre el fraguado. Este trabajo es la fase previa de una amplia investigación experimental realizada en el IETCC, sobre anomalías de fraguado y fenómenos de "aterronamiento" en el cemento portland.

  15. Improving the CO2 performance of cement, part III : The relevance of industrial symbiosis and how to measure its impact

    OpenAIRE

    2015-01-01

    Cement production contributes to extensive CO2 emissions. However, the climate impact can vary significantly between different production systems and different types of cement products. The market is dominated by ordinary Portland cement, which is based on primary raw materials and commonly associated with combustion of vast amounts of fossil fuels. Therefore, the production of Portland cement can be described as a rather linear process. But there are alternative options, for example, involvi...

  16. Durability of Alite-calcium Barium Sulphoaluminate Cement

    Institute of Scientific and Technical Information of China (English)

    LU Lingchao; LU Zeye; LIU Shiquan; WANG Shoude; CHENG Xin

    2009-01-01

    The durability of the cement was mainly studied.Under 1.0 MPa of hydraulic pressure for 8 hours,water could penetrate completely through the sample made by portland cement,but could not penetrate through that by alite-barium sulphoaluminate cement.Under the condition of freezing and thawing cycle,the loss ratio of compressive strength of the cement was only about 17.3%at curing 28 d ages,but the loss of portland cement was as high as 29.5%.Alite-calcium bar-ium sulphoaluminate cement also has an excellent resistance to sulfate attack.The coefficients of resistance to sulfate attack of the cement exceeded 1.0.Meanwhile,the composition and microstructure of the hardened paste of alite-calcium barium sulphoaluminate cement were analyzed by XRD and SEM.

  17. Lodging Update: Portland, Maine

    Directory of Open Access Journals (Sweden)

    Rachel J. Roginsky

    2013-01-01

    Full Text Available Each quarter, Pinnacle Advisory Group prepares an analysis of the New England lodging industry, which provides a regional summary and then focuses in depth on a particular market. These reviews look at recent and proposed supply changes, factors affecting demand and growth rates, and the effects of interactions between such supply and demand trends. In this issue, the authors summarize regional performance for 2012, offer projections for 2013, and spotlight the lodging market in Portland, Maine.

  18. Influence of vinyl acetate-versatic vinylester copolymer on the microstructural characteristics of cement pastes

    OpenAIRE

    Carlos Eduardo Marmorato Gomes; Osny Pellegrino Ferreira; Mauro Roberto Fernandes

    2005-01-01

    To understand the principles of polymer modification and its interference in the formation of some phases of Portland cement composites, several techniques are adopted such as Fourier Transform Infrared Spectroscopy and Thermogravimetric Analysis. In this study, these techniques were adopted to verify the influence of VA/VeoVA copolymer in seven pastes of high-early-strength portland cement twenty-eight days old, being four pastes with different polymer content and the same water/cement ratio...

  19. PART II. HYDRATED CEMENTS

    Directory of Open Access Journals (Sweden)

    Milan Drabik

    2014-09-01

    Full Text Available Essential focus of the study has been to acquire thermoanalytical events, incl. enthalpies of decompositions - ΔH, of technological materials based on two types of Portland cements. The values of thermoanalytical events and also ΔH of probes of technological compositions, if related with the data of a choice of minerals of calcium-silicate-sulfate-aluminate hydrates, served as a valued input for the assessment of phases present and phase changes due to the topical hydraulic processes. The results indicate mainly the effects of "standard humidity" or "wet storage" of the entire hydration/hydraulic treatment, but also the presence of cement residues alongside calcium-silicate-sulfate-aluminate hydrates (during the tested period of treatment. "A diluting" effect of unhydrated cement residues upon the values of decomposition enthalpies in the studied multiphase system is postulated and discussed

  20. POZZOLAN AND CEMENTS WITH POZZOLAN

    Directory of Open Access Journals (Sweden)

    Hasan KAPLAN

    1995-02-01

    Full Text Available Cement, one of the basic material of construction engineering, has an important place in view of strength and cost of structures. Cement consumption is increasing parallel to development of building construction sector. For cement producers, minimal cost is desired by using new and economical material sources. On the other hand, the controllers and contractors need cheaper, safer and higher strength materials. From this respect cement industry tends to use cement with pozzolan. In Türkiye, cement with pozzolan is produced by adding the pozzolan, which has a large reservoir in the country, in cement in sertain amount. However this type of cement is consumed in the construction sector, sortage of scientific investigation and speculative news on the subject.are worried the users and producers. In this paper, prior to an experimental study on the cements having pozzolan additive, historical development of pozzolan, reservoir of Turkiye, and comparison with portland cement is carried out. Advantages and disadvantages of pozzolan are also discussed in some points.

  1. Study on composite Portland cement preparation with limestone and cinder%石灰石-煤渣双掺制备复合硅酸盐水泥的研究

    Institute of Scientific and Technical Information of China (English)

    李志博; 陈平; 刘荣进; 付建莹

    2014-01-01

    用山西朔州当地价格较为低廉的火力发电厂燃煤炉底渣(即煤渣)并配合一定数量的石灰石,进行了复合水泥的试验研究。重点研究了煤渣、石灰石复合使用时,对水泥标准稠度用水量及其力学性能的影响;并采用XRD、SEM,研究了复合水泥的水化机理。研究结果表明:煤渣与石灰石复掺使用时,可以降低水泥标准稠度用水量,强度也能达到要求指标;当石灰石掺量为10%、煤渣掺量为30%时,可以制得28 d抗压强度高达60 MPa的复合水泥。%The composite cement was prepared with Shanxi Shuozhou local low-price power plant cinder in the experimental study. Im-pacts of cinder and limestone on standard cosistency water consumption and mechanical properties of the composite cement were re-searched, and the hydration mechanism was studied. The results show that cinder and limestone together can reduce standard cosisten-cy water cosumption of the composite cement, and the strength can also reach standard indexes;and when limestone ratio is 10%and cinder ratio is 30%, composite cement with 60 MPa 28 d compressive strength can be prepared.

  2. Effect of modified cane molasses on the properties of portland cement%甘蔗糖蜜改性及对硅酸盐水泥性能的影响

    Institute of Scientific and Technical Information of China (English)

    李伟峰; 张胜标; 程云川; 马素花; 沈晓冬

    2013-01-01

    Modified cane molasses was prepared with waste cane molasses from sugar refinery, and the performance as grinding aids of modified cane molasses was studied. The influence of modified cane molasses on the physical properties of cement was also investigated. The research results show that modified cane molasses had good performance as grinding aids of cement, it can obviously reduce 45 μm sieve residue. The setting time of samples with modified of cane molasses was slightly prolonged, and the compressive strength at each age was increased significantly,especially the age of 28 d,can increase 5.3 MPa. The cement paste fluidity was also increased compared to the reference sample.%以糖厂副产物甘蔗糖蜜为原料制备改性糖蜜,研究了其助磨性能及对水泥物理性能的影响.研究结果表明:改性糖蜜对水泥具有较好的助磨性能,显著降低45μm筛筛余量;改性糖蜜使水泥的凝结时间略有延长,可显著提高各龄期的抗压强度,28 d抗压强度最多提高5.3 MPa;水泥净浆流动度也较空白样增大.

  3. Effect of Cement Type on Autogenous Deformation of Cement-Based Materials

    DEFF Research Database (Denmark)

    Pietro, Lura; Ye, Guang; van Breugel, Klaas

    2004-01-01

    In this paper, measurements of non-evaporable water content, chemical shrinkage, autogenous deformation, internal relative humidity (RH), pore solution composition, and early-age elastic modulus are presented and discussed. All experiments were performed on Portland cement and blast-furnace slag...... (BFS) cement pastes. Self-desiccation shrinkage of the BFS cement paste was modeled based on the RH measurements, following the capillary-tension approach. The main findings of this study are: 1) self-desiccation shrinkage can be related to self-desiccation both for Portland and for BFS cement pastes......, taking into account the influence of the dissolved salts in the pore solution, 2) the BFS cement paste studied shows pronounced self-desiccation and self-desiccation shrinkage, mainly caused by its very fine pore structure....

  4. A Concept for Rapid Repair of Bomb-Damaged Runways Using Regulated-Set Cement

    Science.gov (United States)

    1975-07-01

    TAlo0 .CaX , in which X is a halogen; the cement can also be a blended cement produced by grinding together portland - ceraent clinker and a...than those used for portland cement. The accel- erated setting time of the cement is achieved by burning into the cement clinker a controlled amount...4,779, 26 April 1971 British Patent No. 1,311,^25, 25 July 1973 Indian Patent No. 133,6Ul, 5 July 197^ South African Patent No. 3069/71, 3 May 1972

  5. Modelling the effects of waste components on cement hydration

    NARCIS (Netherlands)

    Eijk, van R.J.; Brouwers, H.J.H.

    2001-01-01

    Ordinary Portland Cement (OPC) is often used for the solidification/stabilization (S/S) of waste containing heavy metals and salts. These waste components will precipitate in the form of insoluble compounds on to unreacted cement clinker grains preventing further hydration. In this study the long te

  6. Modelling the effects of waste components on cement hydration

    NARCIS (Netherlands)

    Eijk, van R.J.; Brouwers, H.J.H.

    2000-01-01

    Ordinary Portland Cement (OPC) is often used for the Solidification/Stabilization (S/S) of waste containing heavy metals and salts. These waste componenents will precipitate in the form of insoluble compounds onto unreacted cement clinker grains preventing further hydration. In this study the long t

  7. Application of multi-block methods in cement production

    DEFF Research Database (Denmark)

    Svinning, K.; Høskuldsson, Agnar

    2008-01-01

    Compressive strength at 1 day of Portland cement as a function of the microstructure of cement was statistically modelled by application of multi-block regression method. The observation X-matrix was partitioned into four blocks, the first block representing the mineralogy, the second particle size...

  8. Behavior of multi-walled carbon nanotubes on the porosity and microstructure of cement-based materials

    Science.gov (United States)

    Nochaiya, Thanongsak; Chaipanich, Arnon

    2011-01-01

    The porosity and microstructure of a Portland cement-multi-walled carbon nanotube composite were investigated. Multi-walled carbon nanotubes (CNTs), up to 1 wt.% of cement, synthesized by infusion chemical vapor deposition, and Portland cement type I (PC) were used to produce pastes with a water to cement ratio of 0.5. Mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) were used to characterize Portland cement-CNTs systems. MIP analysis of the results indicates that total porosity of the mixes with CNTs was found to decrease with increasing CNTs content. Moreover, an important effect of additional CNTs was a reduction in the number of mesopores, while SEM technique showed dispersion of CNTs between the hydration phases of Portland cement pastes.

  9. 7 CFR 58.325 - Anhydrous milkfat.

    Science.gov (United States)

    2010-01-01

    ... eligible for official certification, the anhydrous milkfat shall be made by a continuous separation process directly from milk or cream. The cream used shall be comparable to the flavor quality specified above for...

  10. 21 CFR 573.180 - Anhydrous ammonia.

    Science.gov (United States)

    2010-04-01

    ... silage. (2)(i) The food additive anhydrous ammonia is applied directly to corn plant material for use in... to corn plant material containing 28 to 38 percent dry matter. (iv) The silage treated with...

  11. Anhydrous Taphole Mix for Blast Furnace

    Institute of Scientific and Technical Information of China (English)

    Yu Lingyan

    2010-01-01

    @@ 1 Scope This standard specifies the term,definition,brand,label,technical requirements,test methods,quality appraisal procedures,packing,marking,transportation,storage,and quality certificate of anhydrous taphole mix for blast furnace.

  12. Characteristics solidified cement waste using heavy concrete and light concrete paste generated from KRR-2 and UCP

    Energy Technology Data Exchange (ETDEWEB)

    Min, B. Y.; Choi, W. K.; Kim, G. N.; Lee, K. W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-10-15

    As the number of obsolete research reactors and nuclear facilities increases, dismantling nuclear facilities has become an influential issue. During the decommissioning of nuclear plants and facilities, large quantities of slightly contaminated concrete wastes are generated. In Korea, the decontamination and decommissioning of the retired TRIGA MARK II and III research reactors and a uranium conversion plant at KAERI has been under way. By dismantling KRR-2, more than 260 tons of radioactive concrete wastes were generated among the total 2,000 tons of concrete wastes and more than 60 tons of concrete wastes contaminated with uranium compounds have been generated. Typically, the contaminated layer is only 1{approx}10mm thick because cement materials are porous media, the penetration of radionuclides may occur up to several centimeters from the surface of a material. Concrete is a structural material which generally consists of a binder (cement), water, and aggregate. The binder is typically a portland cement which comprises the four principal clinker phases tricalcium silicate (Ca{sub 3}SiO{sub 5}) and constitutes 50-70%, decalcium silicate (Ca{sub 2}SiO{sub 4}), tricalcium aluminate (Ca{sub 3}Al{sub 2}O{sub 6}), and calcium aluminoferrite (Ca{sub 4}Al{sub 2}Fe{sub 2}O{sub 10}). Cement powder (anhydrous cement) created from the co-grinding of clinkers and gypsum is mixed with waster and hydrate phase are formed. The interaction between highly charged C-S-H particles in the presence of divalent calcium counter ions is strongly attractive because of ion-ion correlations and a negligible entropic repulsion. In the temperature range 100-300 .deg. C, these evolutions are mainly attributed to the loss of the bound water from the C-S-H gel. Similar consequences have been reported for mortars and concretes enhanced sometimes by the appearance of micro-cracks related to the strain incompatibilities between the aggregates and the cement paste. Concrete aggregates are combined

  13. Environmental impact assessment of combustible wastes utilization in rotary cement kilns

    OpenAIRE

    2013-01-01

    This study focuses on the environmental impact assessment of the coal combustion and its substitution by alternative fuels from combustible wastes during Portland cement clinker sinterization in rotary cement kiln. Environmental impact assessment was carried out based on the fuels chemical composition and operating parameters of a rotary cement kiln in accordance with EURITS and IMPACT 2002+ methods.

  14. From Rocks to Cement. What We Make. Science and Technology Education in Philippine Society.

    Science.gov (United States)

    Philippines Univ., Quezon City. Science Education Center.

    This module deals with the materials used in making concrete hollow blocks. Topics discussed include: (1) igneous, metamorphic, and sedimentary rocks; (2) weathering (the process of breaking down rocks) and its effects on rocks; (3) cement; (4) stages in the manufacturing of Portland cement; and (5) the transformation of cement into concrete…

  15. Prediction of potential compressive strength of Portland clinker from its mineralogy

    DEFF Research Database (Denmark)

    Svinning, K.; Høskuldsson, Agnar; Justnes, H.

    2010-01-01

    Based on a statistical model first applied for prediction of compressive strength up to 28 d from the microstructure of Portland cement, potential compressive strength of clinker has been predicted from its mineralogy. The prediction model was evaluated by partial least squares regression. The mi...

  16. Maximizing the Sustainability of Cement Utilization in Building Projects through the Use of Greener Materials

    Directory of Open Access Journals (Sweden)

    Mark Bediako

    2016-01-01

    Full Text Available Greener technologies and sustainable developments are currently among the main tools used by many industries in shaping the world for a better future. The construction industry that is known to have numerous negative impact on sustainability is now wide awake on sustainable measures which can aid in reducing its negative impact. In this work, green cement was produced from pyroprocessed clay (PC at 800°C and mixed together with Portland cement. This paper presents both laboratory tests and some field applications of green cement application. Laboratory tests performed included setting times, compressive strength, and shrinkage. Field applications of the green cement are shown. Results from the work showed that well-proportioned greener cement gained strengths between 11% and 30% more than Portland cement at standard curing period of 3, 7, 14, and 28 days. However, in real statistical terms, there was no difference between Portland cement and green cement strength performance. Shrinkage from both total and autogenous tests also showed insignificant differences between the two cements. The study recommends the use of green cements with pozzolanic origin than only Portland cement as a way to maximize sustainability in building projects.

  17. The influence of cement type and temperature on chloride binding in cement paste

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Korzen, Migge Sofie Hoffmann; Skibsted, Jørgen

    1998-01-01

    This paper describes effects of cement type and temperature on chloride binding in cement paste, which is an important subject in relation to life-time modelling of reinforced concrete structures. The influence of cement type on chloride binding is investigated by substituting cement with pure...... cement clinker. Both theoretical considerations and experimental data for chloride binding in cement pastes are presented. A physico-chemically based model to describe the influence of temperature on physical binding of chloride is presented. Solid-state 27Al and 29Si magic-angle spinning (MAS) nuclear...... magnetic resonance (NMR) spectroscopy has been used for quantification of the anhydrous and hydrated aluminate and silicate phases in the chloride exposed cement pastes. The 27Al isotropic chemical shift and nuclear quadrupole coupling is reported for a synthetic sample of Friedel's salt, Ca2Al(OH)6Cl×2H2O....

  18. PURIFIED WASTE FCC CATALYST AS A CEMENT REPLACEMENT MATERIAL

    Directory of Open Access Journals (Sweden)

    Danute Vaiciukyniene

    2015-06-01

    Full Text Available Zeolites are commonly used in the fluid catalytic cracking process. Zeolite polluted with oil products and became waste after some time used. The quantity of this waste inevitably rises by expanding rapidly oil industry. The composition of these catalysts depends on the manufacturer and on the process that is going to be used. The main factors retarding hydration process of cement systems and modifying them strength are organic compounds impurities in the waste FCC catalyst. The present paper shows the results of using purified waste FCC catalyst (pFCC from Lithuania oil refinery, as Portland cement replacement material. For this purpose, the purification of waste FCC catalyst (FCC samples was treated with hydrogen peroxide. Hydrogen peroxide (H2O2 is one of the most powerful oxidizers known. By acting of waste with H2O2 it can eliminate the aforementioned waste deficiency, and the obtained product becomes one of the most promising ingredients, in new advanced building materials. Hardened cement paste samples with FCC or pFCC were formed. It was observed that the pFCC blended cements developed higher strength, after 28 days, compared to the samples with FCC or reference samples. Typical content of Portland cement substituting does not exceed 30 % of mass of Portland cement in samples. Reducing the consumption of Portland cement with utilizing waste materials is preferred for reasons of environmental protection.

  19. Study on the hardening mechanism of cement asphalt binder

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The hydration and hardening mechanism of cement asphalt binder(CAB) was studied.The early hydration process,hydration products and paste microstructure of CAB made by Portland cement and anionic asphalt emulsion were investigated by calorimetry,X-ray diffraction,and environmental scanning electron microscopy.The early hydration process of CAB can be characterized as 5 stages similar to those of Portland cement.There is no chemical reaction detected between cement and asphalt,hence no new hydration products other than those of Portland cement are produced.The hardening of CAB begins with the hydration of cement.When the hydration of cement comes into the acceleration period and its exothermic rate comes to the maximum,the coalescence of asphalt particles in asphalt emulsion is triggered.In the hardened system of CAB,it was found that the hydration products of cement form the skeleton and are covered by the continuous asphalt film.They formed an interpenetrating network system.The emulsifiers in the asphalt emulsion may retard the hydration process of cement.

  20. Caracterização física e mecânica de argamassas à base de cimento Portland e cinza de casca de arroz residual Physical and mechanical characterization on Portland cement mortar with rice husk ash addition

    Directory of Open Access Journals (Sweden)

    Michelle S Rodrigues

    2010-04-01

    Full Text Available A casca de arroz, utilizada como fonte de energia em indústrias de beneficiamento de arroz, converte-se, depois da queima, em uma cinza residual. Esse resíduo, ainda sem um destino adequado, é muitas vezes depositado em grandes áreas abertas e provoca elevado impacto ambiental. Este trabalho teve como objetivo avaliar a viabilidade de utilização da cinza de casca de arroz (CCA residual na produção de argamassas, como substituta parcial do cimento. A caracterização da CCA foi realizada por meio da análise de fluorescência de raios-X (composição química, análise do teor de carbono e difração de raios-X; também foi realizada análise granulométrica a laser. Os corpos de prova foram submetidos a dois tipos de exposição: ambientes externo e interno, com duração máxima de cinco meses. Foram realizados os ensaios de resistência à compressão simples e não destrutivo (velocidade do pulso ultrassônico - VPU. Embora as argamassas tenham apresentado bom desempenho mecânico, os ensaios de pozolanicidade indicaram que a cinza de casca de arroz residual utilizada não é uma pozolana, mas pode ser utilizada em matrizes cimentícias como material inerte (filler.Rice husk, employed as an energy source at milling industries in Brazil generates, after burning, a dark ash. This residue is not yet conveniently disposed, being currently dumped on large areas, causing environmental problems. This research intended to evaluate the applications of residual rice husk ashes (RHA as a partial replacement of cement for mortar production. Rice husk ash was chemically characterized through X-ray fluorescence, determination of carbon content, X-ray diffraction, and laser granulometric analysis. Mortar specimens were submitted to two different exposure conditions: internal and external environments at a maximum period of five months. Physical-mechanical testing were compressive strength and ultrasonic pulse velocity (UPV. Although presenting good

  1. 掺SO3硅酸盐水泥熟料中矿物相形成过程研究%Phase Formation of SO3 Doped Portland Cement Clinker

    Institute of Scientific and Technical Information of China (English)

    许捷; 黎学润; 沈晓冬

    2013-01-01

    Impact of the addition of 3% SO3 on the formation of cement clinker minerals in industrials clinker was investigated. Variation of the C4A3 $ during sintering process was taken into account. Sintering process of the cement clinker was investigated with DSC-TG, X-ray diffraction and microscopic analysis. Results showed that with a higher SO3 content existed,C4A3 $ could formed at 1050 ℃ and decomposed to C3A and C $ from 1290 ℃ ; C3S formed after 1350 ℃ and f-CaO content dropped to 1% at 1450 ℃. The final clinker had 6.2% C4A3 $ . C4A3 $ decomposed completely when held for 0.5 h at 1450 ℃. Calculation of the theoretical mineral formation was in agreement with the above conclusions.%研究了工业原料配料生料中SO3含量为3%时,熟料主要矿物形成过程与含量变化.重点观察了C4A3($)(硫铝酸钙)在烧成过程中的变化情况.借助DSC-TG,X射线衍射法及岩相分析对水泥熟料的烧成过程进行了研究.结果表明,熟料中,C4A3($)在1050℃时即可形成,1290℃开始分解为C3A和C($);1350℃后C3S开始大量形成,1450℃取出急冷,f-CaO的含量小于1%,熟料中有6.2%C4A3($).1450℃保温不同0.Sh后,C4A3($)完全分解.对熟料矿物形成量进行理论计算,结果与实验结论一致.

  2. The suitability of a supersulfated cement for nuclear waste immobilisation

    Science.gov (United States)

    Collier, N. C.; Milestone, N. B.; Gordon, L. E.; Ko, S.-C.

    2014-09-01

    Composite cements based on ordinary Portland cement are used in the UK as immobilisation matrices for low and intermediate level nuclear wastes. However, the high pore solution pH causes corrosion of some metallic wastes and undesirable expansive reactions, which has led to alternative cementing systems being examined. We have investigated the physical, chemical and microstructural properties of a supersulfated cement in order to determine its applicability for use in nuclear waste encapsulation. The hardened supersulfated cement paste appeared to have properties desirable for use in producing encapsulation matrices, but the high powder specific surface resulted in a matrix with high porosity. Ettringite and calcium silicate hydrate were the main phases formed in the hardened cement paste and anhydrite was present in excess. The maximum rate of heat output during hydration of the supersulfated cement paste was slightly higher than that of a 9:1 blastfurnace slag:ordinary Portland cement paste commonly used by the UK nuclear waste processing industry, although the total heat output of the supersulfated cement paste was lower. The pH was also significantly lower in the supersulfated cement paste. Aluminium hydroxide was formed on the surface of aluminium metal encapsulated in the cement paste and ettringite was detected between the aluminium hydroxide and the hardened cement paste.

  3. Nondestructive Handheld Fourier Transform Infrared (FT-IR) Analysis of Spectroscopic Changes and Multivariate Modeling of Thermally Degraded Plain Portland Cement Concrete and its Slag and Fly Ash-Based Analogs.

    Science.gov (United States)

    Leung Tang, Pik; Alqassim, Mohammad; Nic Daéid, Niamh; Berlouis, Leonard; Seelenbinder, John

    2016-05-01

    Concrete is by far the world's most common construction material. Modern concrete is a mixture of industrial pozzolanic cement formulations and aggregate fillers. The former acts as the glue or binder in the final inorganic composite; however, when exposed to a fire the degree of concrete damage is often difficult to evaluate nondestructively. Fourier transform infrared (FT-IR) spectroscopy through techniques such as transmission, attenuated total reflectance, and diffuse reflectance have been rarely used to evaluate thermally damaged concrete. In this paper, we report on a study assessing the thermal damage of concrete via the use of a nondestructive handheld FT-IR with a diffuse reflectance sample interface. In situ measurements can be made on actual damaged areas, without the need for sample preparation. Separate multivariate models were developed to determine the equivalent maximal temperature endured for three common industrial concrete formulations. The concrete mixtures were successfully modeled displaying high predictive power as well as good specificity. This has potential uses in forensic investigation and remediation services particularly for fires in buildings.

  4. Considerations about the use of lime-cement mortars for render conservation purposes

    OpenAIRE

    Torgal, Fernando Pacheco; Faria, Joana; Shasavandi, Arman; Jalali, Said

    2011-01-01

    Some investigations about conservation renders points out that Portland cement based mortars should be avoided and should be replaced by lime-pozzolan mortars. However, this type of mortar is still under investigation and the majority of Portuguese construction enterprises operating in the field of building conservation do not possess enough know-how about them. Besides the absolute rejection of the use of Portland cement based mortars even with just a minimum amount appears to be a dogmat...

  5. Analyses of microstructural properties of VA/VeoVA copolymer modified cement pastes

    OpenAIRE

    Carlos Eduardo M. Gomes; Ferreira,Osny P.

    2005-01-01

    Recently, modern techniques have been applied for analysis of the influence of polymers on microstructural properties of Portland cement, such as Thermogravimetric Analyses (TG), Scanning Electronic Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and Mercury Intrusion Porosimetry (MIP). In this study, thermogravimetric analyses were used to study the influence of vinyl acetate-versatic vinylester copolymer (VA/VeoVA) in seven pastes of 28-day old Portland cement, in which di...

  6. Osteotransductive bone cements.

    Science.gov (United States)

    Driessens, F C; Planell, J A; Boltong, M G; Khairoun, I; Ginebra, M P

    1998-01-01

    Calcium phosphate bone cements (CPBCs) are osteotransductive, i.e. after implantation in bone they are transformed into new bone tissue. Furthermore, due to the fact that they are mouldable, their osteointegration is immediate. Their chemistry has been established previously. Some CPBCs contain amorphous calcium phosphate (ACP) and set by a sol-gel transition. The others are crystalline and can give as the reaction product dicalcium phosphate dihydrate (DCPD), calcium-deficient hydroxyapatite (CDHA), carbonated apatite (CA) or hydroxyapatite (HA). Mixed-type gypsum-DCPD cements are also described. In vivo rates of osteotransduction vary as follows: gypsum-DCPD > DCPD > CDHA approximately CA > HA. The osteotransduction of CDHA-type cements may be increased by adding dicalcium phosphate anhydrous (DCP) and/or CaCO3 to the cement powder. CPBCs can be used for healing of bone defects, bone augmentation and bone reconstruction. Incorporation of drugs like antibiotics and bone morphogenetic protein is envisaged. Load-bearing applications are allowed for CHDA-type, CA-type and HA-type CPBCs as they have a higher compressive strength than human trabecular bone (10 MPa).

  7. [Task 1.] Biodenitrification of low nitrate solar pond waters using sequencing batch reactors. [Task 2.] Solidification/stabilization of high strength and biodenitrified heavy metal sludges with a Portland cement/flyash system

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa, L.; Cook, N.E.; Siegrist, R.L.; Mosher, J.; Terry, S.; Canonico, S.

    1995-09-22

    Process wastewater and sludges were accumulated on site in solar evaporation ponds during operations at the Department of Energy's Rocky Flats Plant (DOE/RF). Because of the extensive use of nitric acid in the processing of actinide metals, the process wastewater has high concentrations of nitrate. Solar pond waters at DOE/RF contain 300-60,000 mg NO{sub 3}{sup {minus}}/L. Additionally, the pond waters contain varying concentrations of many other aqueous constituents, including heavy metals, alkali salts, carbonates, and low level radioactivity. Solids, both from chemical precipitation and soil material deposition, are also present. Options for ultimate disposal of the pond waters are currently being evaluated and include stabilization and solidification (S/S) by cementation. Removal of nitrates can enhance a wastes amenability to S/S, or can be a unit operation in another treatment scheme. Nitrate removal is also a concern for other sources of pollution at DOE/RF, including contaminated groundwater collected by interceptor trench systems. Finally, nitrate pollution is a problem at many other DOE facilities where actinide metals were processed. The primary objective of this investigation was to optimize biological denitrification of solar pond waters with nitrate concentrations of 300--2,100 mg NO{sub 3}{sup {minus}}/L to below the drinking water standard of 45 mg NO{sub 3}{sup {minus}}/L (10 mg N/L). The effect of pH upon process stability and denitrification rate was determined. In addition, the effect Cr(VI) on denitrification and fate of Cr(VI) in the presence of denitrifying bacteria was evaluated.

  8. Comparison of Strength for Concrete with GGBS and Cement Using Accelerated Curing Method

    Directory of Open Access Journals (Sweden)

    K. Shyamala

    2016-10-01

    Full Text Available Ground granulated blast-furnace slag ( GGBS is the granular material formed iron ore is molted. blast furnace slag is by-product of steel manufacture which is sometimes used as a substitute for Portland cement. In steel industry when iron ore is molted, then in the molted state all the impurities come at its surface which are removed called slag. It consists mainly of the silicates and alumino silicates of calcium, which are formed in the blast furnace in molten form simultaneously with the metallic iron. Blast furnace slag is blended with Portland cement clinker to form portland blast furnace slag cement. GGBS is used to make durable concrete structures in combination with ordinary Portland cement and/or other pozzolanic materials. GGBFS has been widely used in Europe, and increasingly in the United States and in Asia (particularly in Japan and Singapore for its superiority in concrete durability, extending the lifespan of buildings from fifty years to a hundred years. This project presents the feasibility of the usage of GGBS as hundred percent substitutes for Ordinary portland cement in concrete. Design mix for M20 and M30 has been calculated using IS 10262-2009 for both accelrated curing in warm water and accelrated curing in boiling water method. Tests were conducted on cubes to study the strength of concrete by using GGBS and Ordinary portland cement

  9. Characteristics and properties of oil-well cements auditioned with blast furnace slag; Cementos petroleros con adicion de escoria de horno alto. Caracteristicas y propiedades

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, R.; Palacios, M.; Puertas, F.

    2011-07-01

    The present paper addresses the alkali activation of Portland cements containing blast furnace slag (20 and 30% by cement weight) with a view to the possible use of these materials in oil well construction. The hydration studies conducted showed that in cement/slag blends, the sodium silicate activator partially inhibited the dissolution of the silicate phases in the Portland cement, retarding cement hydration and reducing the precipitation of reaction products. Due to such partial inhibition, the cement/slag blends had significantly lower mechanical strength than Portland cements hydrated with water. {sup 2}9Si and {sup 2}7Al MAS NMR and BSE/EDX studies, in turn, showed that the CSH gel forming in the alkali-activated cement/slag pastes contained Al in tetrahedral positions and low Ca/Si ratios. (Author) 29 refs.

  10. 75 FR 44304 - Noise Exposure Map Notice, Portland International Airport, Portland, OR

    Science.gov (United States)

    2010-07-28

    ... Noise Exposure Map Notice, Portland International Airport, Portland, OR AGENCY: Federal Aviation... determination that the noise exposure maps submitted by Port of Portland for Portland International Airport under the provisions of 49 U.S.C. 47501 et seq. (Aviation Safety and Noise Abatement Act) and 14...

  11. Cement Conundrum

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    China aims to streamline the crowded cement industry Policymakers are looking to build a concrete wall around the cement-making industry as they seek to solidify the fluid cement market and cut excessive production.

  12. Effect of supplementary cementing materials on the concrete corrosion control

    Energy Technology Data Exchange (ETDEWEB)

    Mejia de Gutierrez, R.

    2003-07-01

    Failure of concrete after a period of years, less than the life expected for which it was designed, may be caused by the environment to which it has been exposed or by a variety of internal causes. The incorporation of supplementary materials has at the Portland cement the purpose of improving the concrete microstructure and also of influence the resistance of concrete to environmental attacks. Different mineral by-products as ground granulated blast furnaces slag (GGBS), silica fume (SF), meta kaolin (MK), fly ash (FA) and other products have been used as supplementary cementing materials. This paper is about the behavior of concrete in the presence of mineral additions. Compared to Portland cements, blended cements show lower heat of hydration, lower permeability, greater resistance to sulphates and sea water. These blended cements find the best application when requirements of durability are regarded as a priority specially on high performance concrete: (Author) 11 refs.

  13. Preparation of sulphoaluminate belite cement from fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, S.; Majling, J. (Slovak Technical Univ., Bratislava (Slovakia). Dept. of Ceramics, Glass and Cement)

    1994-01-01

    Sulphoaluminate belite cements containing the phases C[sub 2]S, C[sub 4]A[sub 3][bar S], C[sub 4]AF, C[bar S] were synthesized from limestone, fly ash and gypsum at 1,200 C. The correspondence between the predicted phase composition and real phase composition were checked. The influence of quantities of different phases in the hydration behavior and strength development were verified. Results show that an optimum proportion of phase quantities help in high strength development in early age. These cements fulfill all the requirement of Portland cement and have very high early strength. Porosity measurements show that the total pore volume in early period is comparatively less than that of Ordinary Portland Cement. Thus these cements can be usable for special purposes.

  14. Macrodefect-free cements: chemistry and impact of the environment

    Energy Technology Data Exchange (ETDEWEB)

    Drabik, M.; Galikova, L.; Mojumdar, S.C. [Slovak Academy of Sciences, Bratislava (Slovakia). Inst. of Inorganic Chemistry

    2002-07-01

    To control and improve the moisture resistance is a long felt necessity of the MDF cements, chemical approaches together with material science contribute to the progress. Present results support our previous hypothesis about the impregnation or barier effect of poly-P on the MDF cements and enlarge the validity of this hypothesis to the blends of SAFB clinker, Portland cement and HPMC or poly-P. Compactness of Al(Fe)-O-P cross-links increases the intrinsic density and, consequently, impregnates the system against the uptake of moisture. In a sense of the theory of functional polymers, the intensity of grafting of polymer chains to the surface of grains increases if poly-P is used and with the prolonged processing. The scope of moisture attack on MDF cements synthesized from the blends of SAFB clinker, Portland cement and HPMC or poly-P, as quantified using mass changes as measure of moisture resistance, is strongly affected by the nature of polymer. The addition of Portland cement in the raw mix improves the moisture resistance of MDF cements. Thermal analysis shows: (i) the irreversible mass gain of 3 - 10% is arisen from carbonation and secondary hydration of cement grains and (ii) the Al(Fe)-O-C(P) cross-links remain intact in the moist environment at either ambient or extreme levels of humidity. (orig.)

  15. Analysis of Pore Structures and Their Relations with Strength of Hardened Cement Paste

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wensheng; LI Beixing; WANG Hongxia; WEI Jiangxiong; CHEN Yimin

    2005-01-01

    Three cement samples were prepared, including OPC consisted of 100wt% portland cement, PFA consisted of 70wt% portland cement and 30wt% fly-ash, and CA consisted of 70wt% portland cement and 30wt% modified fly ash. The strength of hardened cement paste of these samples was tested and their pore structures were determined by a mercury intrusion porosimeter. Moreover,the data of the pore structures of three samples were comprehensively analyzed. The relations between the pore structures and the compressive strength of the three samples were studied. The experimental results show that the relations between the porosity determined by the mercury intrusion porosimeter and the compressive strength are not notable, and the total pore surface area, the average pore diameter and the median pore diameter could be used to explain the difference of the strength of the tested samples.

  16. Energetically Modified Cement (EMC) - Performance Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Ronin, Vladimir; Elfgren, Lennart [Luleaa Univ. of Technology (Sweden). Centre for High Performance Cement

    2003-03-01

    Energetically Modified Cements, EMC, made of intensively milled cement (50%) and fillers (50%) of quartz or fly ash have been compared to blends of Ordinary Portland Cement, OPC, and fillers. The EMCs have better properties than other blends and are comparable to unblended OPC. This remarkable fact can probably be explained as follows. The grinding process reduces the size of both cement grains and fillers. This combined with the creation of micro defects gives the ground cement a very high degree of hydration. The increased early hydration and a better distribution of hydration products results in an extensive pore size refinement of the hardened binder. This pore size refinement leads to a favorably reduced permeability and diffusivity and very good mechanical properties.

  17. Influence of adjuvants on the properties of underwater cast concrete on base of cement (HRS 32.5 N

    Directory of Open Access Journals (Sweden)

    Rouis Mohamed Jamel

    2014-04-01

    *The characterization tests of concrete in the hardened state including destructive and non destructive tests performed on specimens made in concrete (based on portland cement, with varying dosages and adjuvants at different times (28d and 90d.

  18. NQR frequencies of anhydrous carbamazepine polymorphic phases

    CERN Document Server

    Bonin, C J; Pusiol, D J

    2010-01-01

    In this work we propose the Nuclear Quadrupole Resonance (NQR) technique as an analytical method suitable for polymorphism detection in active parts (or active principles) of pharmaceuticals with high pharmacological risk. Samples of powder carbamazepine (5H-dibenz(b,f)-azepine-5-carboxamide) are studied. In its anhydrous state, this compound presents at least three different polymorphic forms: form III, the commercial one, form II, and form I. Of these, only form III possesses desirable therapeutic effects. By using the NQR technique, it was possible to characterize two of the three polymorphic phases (I and III) for anhydrous carbamazepine in few minutes at room temperature, detecting the characteristic frequencies of 14N nuclei (I=1) present in their chemical composition and in the frequency range 2.820-3.935 MHz. For form II, characteristic lines were not detected within this range of frequencies. The lines detected for form III are centered at the frequencies \

  19. Hydration of Portoguese cements, measurement and modelling of chemical shrinkage

    DEFF Research Database (Denmark)

    Maia, Lino; Geiker, Mette Rica; Figueiras, Joaquim A.

    2008-01-01

    form of the dispersion model. The development of hydration varied between the investigated cements; based on the measured data the degree of hydration after 24 h hydration at 20 C varied between 40 and 50%. This should be taken into account when comparing properties of concrete made from the different......Development of cement hydration was studied by measuring the chemical shrinkage of pastes. Five types of Portuguese Portland cement were used in cement pastes with . Chemical shrinkage was measured by gravimetry and dilatometry. In gravimeters results were recorded automatically during at least...

  20. Plastic and free shrinkages cracking of blended white cement concrete

    Energy Technology Data Exchange (ETDEWEB)

    Rashad, A.M.; White, T.; Ariaratnam, S.; Knutson, K. [Housing and Building National Research Center, Cairo (Egypt)

    2007-07-01

    This paper presented the results of a study that investigated the plastic and free shrinkages of white portland cement concrete, concrete incorporating silica fume (SF) and concrete incorporating metakaolin (MK) compared to regular plain gray portland cement concrete. An experimental program was designed to investigate the plastic and free shrinkage of concrete containing gray and white blended cement. The paper discussed the experimental details including materials and cement types such as SF, MK, aggregate, and superplasticizer as well as concrete mixtures and specimen preparation including mixture proportions, preparation and curing of concrete specimens, and test specimens. It also presented the determination of concrete properties such as slump of fresh concrete, plastic shrinkage, and dry shrinkage. Test results and discussion of results were also provided. It was concluded that plain white portland cement concrete showed less number of plastic cracks but slightly higher average crack width compared to other concrete mixtures with MK or SF. In addition, free shrinkage behavior of plain white cement and plain gray cement matrix was comparable. 23 refs.

  1. The suitability of a supersulfated cement for nuclear waste immobilisation

    Energy Technology Data Exchange (ETDEWEB)

    Collier, N.C., E-mail: nick.collier@sheffield.ac.uk [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Milestone, N.B. [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Callaghan Innovation, 69 Gracefield Road, PO Box 31310, Lower Hutt 5040 (New Zealand); Gordon, L.E. [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Geopolymer and Minerals Processing Group, Department of Chemical and Biomolecular Engineering, University of Melbourne, Parkville, Victoria 3010 (Australia); Ko, S.-C. [Holcim Technology Ltd, Hagenholzstrasse 85, CH-8050 Zurich (Switzerland)

    2014-09-15

    Highlights: • We investigate a supersulfated cement for use as a nuclear waste encapsulant. • High powder fineness requires a high water content to satisfy flow requirements. • Heat generation during hydration is similar to a control cement paste. • Typical hydration products are formed resulting in a high potential for waste ion immobilisation. • Paste pH and aluminium corrosion is less than in a control cement paste. - Abstract: Composite cements based on ordinary Portland cement are used in the UK as immobilisation matrices for low and intermediate level nuclear wastes. However, the high pore solution pH causes corrosion of some metallic wastes and undesirable expansive reactions, which has led to alternative cementing systems being examined. We have investigated the physical, chemical and microstructural properties of a supersulfated cement in order to determine its applicability for use in nuclear waste encapsulation. The hardened supersulfated cement paste appeared to have properties desirable for use in producing encapsulation matrices, but the high powder specific surface resulted in a matrix with high porosity. Ettringite and calcium silicate hydrate were the main phases formed in the hardened cement paste and anhydrite was present in excess. The maximum rate of heat output during hydration of the supersulfated cement paste was slightly higher than that of a 9:1 blastfurnace slag:ordinary Portland cement paste commonly used by the UK nuclear waste processing industry, although the total heat output of the supersulfated cement paste was lower. The pH was also significantly lower in the supersulfated cement paste. Aluminium hydroxide was formed on the surface of aluminium metal encapsulated in the cement paste and ettringite was detected between the aluminium hydroxide and the hardened cement paste.

  2. The use of anhydrous ammonia for bioventing

    Energy Technology Data Exchange (ETDEWEB)

    Zytner, R.G.; Hallman, M.; Gimenez, B.F.; Jennings, R.; Leek, K. [Guelph Univ., ON (Canada). Faculty of Graduate Studies

    2002-07-01

    Soils contaminated with hydrocarbons can be effectively treated using bioventing remediation technology, an ideal method for removing residual contamination left by soil vapour extraction (SVE). Bioventing uses low or intermitted air flow rates to produce oxygen-rich conditions in the vadose zone, thereby promoting the formation of micro-organisms that can mineralize the hydrocarbons if enough nutrients are present. There is concern regarding the use of nutrients (the addition of nitrogen) to the subsurface because current applications methods cannot uniformly disperse nitrogen throughout the entire subsurface. Two research studies are being conducted using gasoline contaminated soil to address this concern. The first phase of the study focuses on how to best deliver nitrogen to the subsurface. Injecting anhydrous ammonia into the contaminated surface was one suggestion for stimulating the growth of hydrocarbon degraders. SVE extraction well models indicated this was an effective and safe way to disperse nitrogen. The second phase of the study involved the use of respirometers to compare total petroleum hydrocarbon (TPH) degradation with nitrogen additions in the form of NH{sub 4}Cl or anhydrous ammonia. The respirometers were run for about 1 month after which time it was determined that the use of anhydrous ammonia is an effective method to promote bioventing.

  3. Atividade antimicrobiana do metronidazol gel associado ao hidróxido de cálcio e ao cimento Portland frente às bactérias anaeróbias relacionadas a reações periapicais do tipo crônica = The antibacterial activity of the metronidazole gel associated with calcium hydroxide and cement portland front the anaerobic bacterias related to cronic periapical lesions

    Directory of Open Access Journals (Sweden)

    Mendonça, Eduarda Rodrigues da Silva

    2007-01-01

    Full Text Available As pesquisas com o intuito de descobrir novas substâncias com finalidade para medicação intracanal é uma realidade. Tem como objetivos principais a melhoria das propriedades dos medicamentos utilizados usualmente, tais como o hidróxido de cálcio para com isso suprir algumas deficiêcias que possam existir. Este trabalho teve como propósito a análise in vitro da ação do metronidazol gel em associação ao hidróxido de cálcio e cimento Portland, como medicação intracanal. Os testes foram realizados em bactérias anaeróbias facultativas, as quais compõe a flora de dentes portadores de reação periapical crônica. O hidróxido de cálcio é, ainda, a medicação intracanal mais utilizada, visto que, possui efeito antibacteriano pronunciado contra a maioria dos microrganismos existentes no interior de canais radiculares infectados. O metronidazol veio a ser testado por possuir capacidade bactericida atuante, principalmente, em bactérias anaeróbias estritas. Podendo atuar nos microrganismos que são resistentes à ação do hidróxido de cálcio. Entretanto, ao término deste experimento, o metronidazol gel quando testado, comparado e associado ao hidróxido de cálcio e cimento Portland não teve resposta superior a ação do hidróxido de cálcio puro como medicação intracanal, tendo o cimento Portland apenas melhorado as propriedades físico/química dessa pasta

  4. Physicochemical and biological properties of Portland cement and mineral trioxide aggregate and their applications%三氧化聚合物与波特兰水门汀的理化和生物学性能及其应用

    Institute of Scientific and Technical Information of China (English)

    吴雨鸿; 林居红; 张红梅

    2014-01-01

    Mineral trioxide aggregate(MTA) and Portland cement(PC) contain calcium oxide, which reacts with water to form calcium hydroxide and producesa highly alkaline environment that inhibits bacterial growth. Compared with white PC(WPC) and MTA, gray Portland cement(GPC) has high concentrations of harmful heavy metals, namely arsenic, chromium, and lead. The solubility of root-canal filling affects itsability to close. The overall apical closure performances of MTA and PC are relatively similar. Good oral materials should have appropriate setting times. Addition of calcium chloride or calcium formate to MTA and PC shortens their setting time. The particle size of the material also affects its closure, setting time, compressive strength, and abrasion resistance. The average particle size of WPC is greater than that of MTA; however, the compressive strength of the former is lower than that of the latter. When mixed with gold powder, the compressive strength of WPC is similar to that of MTA. MTA and PC are non-toxic and genotoxic, and their toxicities to Chinese hamster ovary cells showno significant difference. Moreover, MTA and PC exhibit antibacterial activities toward Micrococcus luteus, Staphylococcus aureus, Escherichia coli, and other microorganisms. MTA and PC can promote hard tissue mineralization, which can leadto crown discolorations; PC results in lighter colors compared with those observed from MTA. Applications of MTA are limited by its long setting time, tooth discoloration, high-cost, and difficultyof removal. Thus, PC can be an economical alternative to MTA for dental restoration. The long-term effects of this material, however, are still uncertain and require longer assessments.%三氧化聚合物(MTA)和波特兰水门汀(PC)均含有氧化钙,氧化钙与水反应生成氢氧化钙,这样的一个高碱性环境抑制细菌的生长。灰色波特兰水门汀(GPC)中对人体危害的重金属元素铅、砷和铬的质量较白色波特

  5. HYDRATING CHARACTERISTICS OF MODIFIED PORTLAND WITH Ba-BEARING SULPHOALUMINATE MINERALS

    Directory of Open Access Journals (Sweden)

    Chenchen Gong

    2016-03-01

    Full Text Available The hydrating characteristics of modified Portland cement with Ba-bearing sulphoaluminate minerals were studied in this paper. Scanning Electron Microscopy-Energy Dispersive Spectrometer (SEM-EDS, mercury intrusion porosimeter (MIP and compressive strength were determined to characterize hydrating products and microstructure. Results show that basic physical properties of modified Portland cement with Ba-bearing sulphoaluminate minerals (SMPC are similar with PC except the shorter setting time. Ettringite and C-S-H are the main hydrating produces in SMPC, which is similar to Portland cement (PC. Because of volume expansion of ettringite, SMPC paste structure is denser than PC according to SEM-EDS analysis and the pore size and pore content of SMPC pastes was smaller especially for the harmful pores. Because sulfur aluminum barium calcium was a new early-strength mineral and parts of BaO went into the C₂S lattice and caused lattice distortion to enhance C₂S hydration activity, the compressive strengths of SMPC grew faster and higher than PC.

  6. Sustainable development of the cement industry and blended cements to meet ecological challenges.

    Science.gov (United States)

    Sobolev, Konstantin

    2003-05-05

    The world production of cement has greatly increased in the past 10 years. This trend is the most significant factor affecting technological development and the updating of manufacturing facilities in the cement industry. Existing technology for the production of cement clinker is ecologically damaging; it consumes much energy and natural resources and also emits pollutants. A new approach to the production of blended or high-volume mineral additive (HVMA) cement helps to improve its ecological compatibility. HVMA cement technology is based on the intergrinding of portland cement clinker, gypsum, mineral additives, and a special complex admixture. This new method increases the compressive strength of ordinary cement, improves durability of the cement-based materials, and--at the same time--uses inexpensive natural mineral additives or industrial by-products. This improvement leads to a reduction of energy consumption per unit of the cement produced. Higher strength, better durability, reduction of pollution at the clinker production stage, and decrease of landfill area occupied by industrial by-products, all provide ecological advantages for HVMA cement.

  7. Sustainable Development of the Cement Industry and Blended Cements to Meet Ecological Challenges

    Directory of Open Access Journals (Sweden)

    Konstantin Sobolev

    2003-01-01

    Full Text Available The world production of cement has greatly increased in the past 10 years. This trend is the most significant factor affecting technological development and the updating of manufacturing facilities in the cement industry. Existing technology for the production of cement clinker is ecologically damaging; it consumes much energy and natural resources and also emits pollutants. A new approach to the production of blended or high-volume mineral additive (HVMA cement helps to improve its ecological compatibility. HVMA cement technology is based on the intergrinding of portland cement clinker, gypsum, mineral additives, and a special complex admixture. This new method increases the compressive strength of ordinary cement, improves durability of the cement-based materials, and - at the same time - uses inexpensive natural mineral additives or industrial by-products. This improvement leads to a reduction of energy consumption per unit of the cement produced. Higher strength, better durability, reduction of pollution at the clinker production stage, and decrease of landfill area occupied by industrial by-products, all provide ecological advantages for HVMA cement.

  8. EVALUATION OF CEMENT THIXOTROPY FOR THE CEMENT OF OIL WELLS IN AREAS WITH LOSSES: EFFECT OF PLASTER AND DAIRY OF HIGH FURNACES

    Directory of Open Access Journals (Sweden)

    T. Bouziani

    2010-12-01

    Full Text Available Cementing of oil and gas wells can be a very delicate operation. Among the concerns of service companies, during this operation are the nature and conditions of the formations in well. This is the case of cementing operations in southern Algeria, specifically on the fields of In-Amen, where the formations in lost zones are naturally weak and highly permeable. In these areas, drilling fluids (muds and cements pumped will be, completely or partially lost, what we call "lost circulation". Thixotropic cements are useful to overcome lost circulation problems. They are characterized by a special rheological behavior, allowing it to plug lost zones when they are pumped. Our work aims to assess the thixotropy of cements perapred with two types of cement (class G Asland cement and CEM I 42.5 portland cement with the plaster, using a viscometer with coaxial cylinder (couette type. Moreover, the effect of blast furnace slag (LHF on the properties and thixotropic mixtures prepared was also studied. The results show that portland cement (available locally can produce mixes with higher and more stable thixotropy than the class G cement (from importation, which is a practical and economical for cementing job operations in wells with loss zones. The results also show that the effect of LHF is positive, since in addition to his contribution to long term performances, especially the durability of hardened concrete, it improves the thixotropy of cement made of plaster.

  9. An element with a liquid, anhydrous electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Nankay, S.; Indzima, T.; Toyeguti, Y.

    1982-09-01

    A liquid anhydrous element and a heat treated Mn0/sub 2/ cathode, to which sodium silicate in the form of Na/sub 2/0 with 5/2Si0/sub 2/ liquid glass is added in a volume of 3 grams per 100 grams of Mn0/sub 2/ is used in the element with a light metal, lithium type anode. Moreover 4.5 grams of acetylene soot is added to the active cathode mass. A fluorine bearing resin is used as the binder. The cathode stores well.

  10. Global warming impact on the cement and aggregates industries

    Energy Technology Data Exchange (ETDEWEB)

    Davidovits, J. (Cordi-Geopolymere SA, Saint-Quentin (France). Geopolymer Inst.)

    1994-06-01

    CO[sub 2] related energy taxes are focusing essentially on fuel consumption, not on actual CO[sub 2] emission measured at the chimneys. Ordinary Portland cement, used in the aggregates and industries, results from the calcination of limestone and silica. The production of 1 ton of cement directly generates 0.55 tons of chemical-CO[sub 2] and requires the combustion of carbon-fuel to yield an additional 0.40 tons of CO[sub 2]. The 1987 1 billion metric tons world production of cement accounted for 1 billion metric tons of CO[sub 2], i.e., 5% of the 1987 world CO[sub 2] emission. A world-wide freeze of CO[sub 2] emission at the 1990 level as recommended by international institutions, is incompatible with the extremely high cement development needs of less industrialized countries. Present cement production growth ranges from 5% to 16% and suggests that in 25 years from now, world cement CO[sub 2] emissions could equal 3,500 million tons. Eco-taxes when applied would have a spectacular impact on traditional Portland cement based aggregates industries. Taxation based only on fuel consumption would lead to a cement price increase of 20%, whereas taxation based on actual CO[sub 2] emission would multiply cement price by 1.5 to 2. A 25--30% minor reduction of CO[sub 2] emissions may be achieved through the blending of Portland cement with replacement materials such as coal-fly ash and iron blast furnace slag.

  11. Reuse of cement-solidified municipal incinerator fly ash in cement mortars: physico-mechanical and leaching characteristics.

    Science.gov (United States)

    Cinquepalmi, Maria Anna; Mangialardi, Teresa; Panei, Liliana; Paolini, Antonio Evangelista; Piga, Luigi

    2008-03-01

    The reuse of cement-solidified Municipal Solid Waste Incinerator (MSWI) fly ash (solidified/stabilised (S/S) product) as an artificial aggregate in Portland cement mortars was investigated. The S/S product consisted of a mixture of 48 wt.% washed MSWI fly ash, 20 wt.% Portland cement and 32 wt.% water, aged for 365 days at 20 degrees C and 100% RH. Cement mortars (water/cement weight ratio=0.62) were made with Portland cement, S/S product and natural sand at three replacement levels of sand with S/S product (0%, 10% and 50% by mass). After 28 days of curing at 20 degrees C and 100% RH, the mortar specimens were characterised for their physico-mechanical (porosity, compressive strength) and leaching behaviour. No retardation in strength development, relatively high compressive strengths (up to 36 N/mm2) and low leaching rates of heavy metals (Cr, Cu, Pb and Zn) were always recorded. The leaching data from sequential leach tests on monolithic specimens were successfully elaborated with a pseudo-diffusional model including a chemical retardation factor related to the partial dissolution of contaminant.

  12. Continuous monitoring of the zinc-phosphate acid-base cement setting reaction by proton nuclear magnetic relaxation

    Science.gov (United States)

    Apih, T.; Lebar, A.; Pawlig, O.; Trettin, R.

    2001-06-01

    Proton nuclear magnetic relaxation is a well-established technique for continuous and non destructive monitoring of hydration of conventional Portland building cements. Here, we demonstrate the feasibility of nuclear magnetic resonance (NMR) monitoring of the setting reaction of zinc-phosphate acid-base dental cements, which harden in minutes as compared to days, as in the case of Portland cements. We compare the setting of cement powder (mainly, zinc oxide) prepared with clinically used aluminum-modified orthophosphoric acid solution with the setting of a model system where cement powder is mixed with pure orthophosphoric acid solution. In contrast to previously published NMR studies of setting Portland cements, where a decrease of spin-lattice relaxation time is attributed to enhanced relaxation at the growing internal surface, spin-lattice relaxation time T1 increases during the set of clinically used zinc-phosphate cement. Comparison of these results with a detailed study of diffusion, viscosity, and magnetic-field dispersion of T1 in pure and aluminum-modified orthophosphoric acid demonstrates that the increase of T1 in the setting cement is connected with the increase of molecular mobility in the residual phosphoric acid solution. Although not taken into account so far, such effects may also significantly influence the relaxation times in setting Portland cements, particularly when admixtures with an effect on water viscosity are used.

  13. A comprehensive model to describe radiolytic processes in cement medium

    DEFF Research Database (Denmark)

    Bouniol, P.; Bjergbakke, Erling

    2008-01-01

    Basic mechanisms controlling the radiolysis in cementitious matrices are reviewed in the specific context of the gamma irradiation, in closed system without upper vapour space, at 25 degrees C, with a pore solution representative of a Portland cement paste. A general survey of data corresponding...

  14. The Effect Of Pozzolan Surface Properties On Physical And Mechanical Properties Of Cement Mortars

    OpenAIRE

    KOÇAK, YILMAZ; DORUM, Atila; Bülent YILMAZ; UCAR, Ali

    2010-01-01

    This study aims to determine mutual influence on blast furnace slag, fly ash and cement with added trass with Portland cement. For this purpose, physical, chemical, XRD, FT-IR, zeta (electrokinetic) potential and standard cement tests were applied to materials. In this study, it is shown that physical characteristics of pozzolan mostly depend on their molecular structures. Properties of molecular structure, in addition to its chrystal and amorphous character, change based on the existence of ...

  15. Corrosion Resistance of High Strength Concrete Containing Palm Oil Fuel Ash as Partial Cement Replacement

    OpenAIRE

    F. Mat Yahaya; Muthusamy, K.; Sulaiman, N.

    2014-01-01

    This experimental work investigates the influence of POFA as partial cement replacement towards corrosion resistance of high strength concrete. Plain high strength concrete (P0) with 100% ordinary Portland cement (control specimen) and POFA high strength concrete containing POFA as partial cement replacement material were used. At the first stage, mix with 20% POFA (P20) has been identified as the best performing mix after cubes (150×150×150 mm) containing various content of POFA as partial c...

  16. Cement Formation

    DEFF Research Database (Denmark)

    Telschow, Samira; Jappe Frandsen, Flemming; Theisen, Kirsten

    2012-01-01

    Cement production has been subject to several technological changes, each of which requires detailed knowledge about the high multiplicity of processes, especially the high temperature process involved in the rotary kiln. This article gives an introduction to the topic of cement, including...... an overview of cement production, selected cement properties, and clinker phase relations. An extended summary of laboratory-scale investigations on clinkerization reactions, the most important reactions in cement production, is provided. Clinker formations by solid state reactions, solid−liquid and liquid...

  17. 46 CFR 98.25-5 - How anhydrous ammonia may be carried.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false How anhydrous ammonia may be carried. 98.25-5 Section 98... Anhydrous Ammonia in Bulk § 98.25-5 How anhydrous ammonia may be carried. (a) Anhydrous ammonia shall be..., except as otherwise provided in paragraph (b) of this section. (b) When anhydrous ammonia is to...

  18. Modeling the influence of limestone addition on cement hydration

    Directory of Open Access Journals (Sweden)

    Ashraf Ragab Mohamed

    2015-03-01

    Full Text Available This paper addresses the influence of using Portland limestone cement “PLC” on cement hydration by characterization of its microstructure development. The European Standard EN 197-1:2011 and Egyptian specification ESS 4756-1/2009 permit the cement to contain up to 20% ground limestone. The computational tools assist in better understanding the influence of limestone additions on cement hydration and microstructure development to facilitate the acceptance of these more economical and ecological materials. μic model has been developed to enable the modeling of microstructural evolution of cementitious materials. In this research μic model is used to simulate both the influence of limestone as fine filler, providing additional surfaces for the nucleation and growth of hydration products. Limestone powder also reacts relatively slow with hydrating cement to form monocarboaluminate (AFmc phase, similar to the mono-sulfoaluminate (AFm phase formed in ordinary Portland cement. The model results reveal that limestone cement has accelerated cement hydration rate, previous experimental results and computer model “cemhyd3d” are used to validate this model.

  19. Ageing of Dry Cement Mixes for Finishing Purposes

    Directory of Open Access Journals (Sweden)

    Bronius VEKTARIS

    2013-09-01

    Full Text Available Dry building mixes, stored in the air, absorb water vapor and CO2 gas and ageing because properties of binding materials, mostly Portland cement, deteriorate after its prehydration and carbonation. In this paper the ageing singularities of dry cement mixes for finishing purposes and additives for retarding this process has been determinated. Ordinary and quickly hardening Portland cements absorb H2O and CO2 more than white cement – about 70 % – 75 % and 30 % – 38 % per month of innitial mass, respectively. White cement is more resistant to prehydration and carbonation, because it contains less C3A, C4AF and alkali, characterized initial activity. Dry mixes with white cement, although slower, but still worse after stored. Influence of routine dry mortar mixes ingredients and additives (methyl cellulose, pigments, sand and lime on prehydration properties of the mixes for finishing purpose is not substantial. Significant positive influence comes from the addition of fatty acid salts (zinc stearate or sodium oleate. The dry cement mixes for finishing purpose has been recomended to hydrophobisate with one of these additives, adding about 1 % by weight of cement during preducing mixes. DOI: http://dx.doi.org/10.5755/j01.ms.19.3.5243

  20. Effective Permeability Change in Wellbore Cement with Carbon Dioxide Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Um, Wooyong; Jung, Hun Bok; Martin, Paul F.; McGrail, B. Peter

    2011-11-01

    Portland cement, a common sealing material for wellbores for geological carbon sequestration was reacted with CO{sub 2} in supercritical, gaseous, and aqueous phases at various pressure and temperature conditions to simulate cement-CO{sub 2} reaction along the wellbore from carbon injection depth to the near-surface. Hydrated Portland cement columns (14 mm diameter x 90 mm length; water-to-cement ratio = 0.33) including additives such as steel coupons and Wallula basalt fragments were reacted with CO{sub 2} in the wet supercritical (the top half) and dissolved (the bottom half) phases under carbon sequestration condition with high pressure (10 MPa) and temperature (50 C) for 5 months, while small-sized hydrated Portland cement columns (7 mm diameter x 20 mm length; water-to-cement ratio = 0.38) were reacted with CO{sub 2} in dissolved phase at high pressure (10 MPa) and temperature (50 C) for 1 month or with wet CO{sub 2} in gaseous phase at low pressure (0.2 MPa) and temperature (20 C) for 3 months. XMT images reveal that the cement reacted with CO{sub 2} saturated groundwater had degradation depth of {approx}1 mm for 1 month and {approx}3.5 mm for 5 month, whereas the degradation was minor with cement exposure to supercritical CO{sub 2}. SEM-EDS analysis showed that the carbonated cement was comprised of three distinct zones; the innermost less degraded zone with Ca atom % > C atom %, the inner degraded zone with Ca atom % {approx} C atom % due to precipitation of calcite, the outer degraded zone with C atom % > Ca atom % due to dissolution of calcite and C-S-H, as well as adsorption of carbon to cement matrix. The outer degraded zone of carbonated cement was porous and fractured because of dissolution-dominated reaction by carbonic acid exposure, which resulted in the increase in BJH pore volume and BET surface area. In contrast, cement-wet CO{sub 2}(g) reaction at low P (0.2 MPa)-T (20 C) conditions for 1 to 3 months was dominated by precipitation of micron

  1. Investigation of k-struvite formation in magnesium phosphate cements

    OpenAIRE

    LE ROUZIC, Mathieu; Chaussadent, Thierry; Stefan, Lavinia; PLATRET, Gérard

    2014-01-01

    Magnesium phosphate cements can be used as an alternative of Portland cements for the stabilization/solidification (S/S) process of specific wastes like mercury, lead, … These cements are based on the reaction between magnesium oxide (MgO) and monopotassium phosphate (KH2PO4) mixed with water which leads to the formation of the solid skeleton of the matrix: MgO + KH2PO4 + 5H2O  MgKPO4.6H2O. The development of k-struvite crystals (MgKPO4.6H2O) leads to the setting of these ...

  2. Chromium speciation in hazardous, cement-based waste forms

    Science.gov (United States)

    Lee, J. F.; Bajt, S.; Clark, S. B.; Lamble, G. M.; Langton, C. A.; Oji, L.

    1995-02-01

    XANES and EXAFS techniques were used to determine the oxidation states and local structural environment of Cr in cement-based waste forms. Results show that Cr in untreated Portland cement formulations remains as toxic Cr 6+, while slag additives to the cement reduce Cr 6+ to the less toxic, less mobile Cr 3+ species. EXAFS analysis suggests that the Cr 6+ species is surrounded by four nearest oxygen atoms, while the reduced Cr 3+ sp ecies is surrounded by six oxygen atoms. The fitted CrO bond lengths for Cr 6+ and Cr 3+ species are around 1.66 and 1.98 Å, respectively.

  3. Study of Compressive Strength of Concrete with Coal Power Plant Fly Ash as Partial Replacement of Cement and Fine Aggregate

    Directory of Open Access Journals (Sweden)

    FAREED AHMED MEMON

    2010-10-01

    Full Text Available This research study comprises of concrete cubes made with Ordinary Portland Cement and with different configurations of fly ash by replacing cement and fine aggregate. To achieve the aim of this study, total 81 concrete cubes were cast. Among 81 cubes, 9 cubes were made with normal concrete, 36 cubes were made by replacing 25%, 50%, 75% and 100% of fine aggregate with fly ash and 36 cubes were made by replacing 10%, 25%, 50%, and 75% of cement with fly ash. The cubes were 6\\" x 6\\" in cross-section, and the mix design was aimed for 5000 psi. After proper curing of all 81 cubes, they were tested at 3, 7 and 28 days curing age. The cubes were tested in Forney Universal Testing Machine. By analyzing the test results of all the concrete cubes, the following main findings have been drawn. The compressive strength of concrete cubes made by replacing 100 % fine aggregate by fly ash was higher than the concrete cubes made with Ordinary Portland Cement at all 3, 7 and 28 days curing ages. On the other hand, the compressive strength of concrete cubes made by replacing 10 % and 25 % cement by fly ash was slightly lower than the concrete cubes made with Ordinary Portland Cement at all curing ages, whereas, the compressive strength of concrete cubes made by replacing 50 % and 75 % of cement by fly ash were quite lower than the concrete cubes made with Ordinary Portland Cement at all curing ages.

  4. Influence of relationship water/cement upon the processing of cements with pozzolana in standard mortar

    Directory of Open Access Journals (Sweden)

    Gener Rizo, M.

    2002-03-01

    Full Text Available The processing of standard mortar is completed following different methods in accordance with the country, but they exist two fundamental tendecies, the ISO and the ASTM. The cuban norm for mechanic-physic tests is based in ISO, and so they use a constant relationship water/cement in the processing of standard mortar a great problem concerning the cement users when they tested those mixed with puzzolanes, because they don't take care of the bigger water needs of those materials. In this work we present an study of the behaviour of Pozzolanic Portland cements (PP-250 elaborates with a fix and changeable relationship water/cement, obtained starting from the fluidity of the pure Portland cement. (P-350 The results obtained shows that the mechanical resistance decreased in cement mortars PP-250 realised with changeable relationship water/cement. So we recommend the adoption of an optional procedure to elaborate a quality mortar with pozzolana cements.

    La elaboración del mortero normalizado se realiza internacionalmente por diferentes métodos, pero existen dos tendencias fundamentales, la enunciada por ISO y por ASTM. La norma cubana de ensayos físico-mecánicos de cemento se basa en la norma ISO, por lo que para la elaboración del mortero normalizado se utiliza una relación agua/cemento constante. Esto ha provocado discrepancias con los usuarios del cemento, especialmente cuando se ensayan los cementos que contienen puzolanas, ya que se plantea que no se tiene en cuenta la mayor demanda de agua de estos materiales. En el presente trabajo se presenta un estudio del comportamiento de cementos Portland Puzolánicos (PP-250 elaborados con una relación agua/ cemento fija y variable, lograda a partir de la fluidez de la pasta de cemento Portland puro (P-350. Los resultados obtenidos indican que se producen disminuciones en la resistencia mecánica en los morteros de cemento PP-250 elaborados con agua/ cemento variable y recomienda la

  5. Cement with silica fume and granulated blast-furnace slag: strength behavior and hydration

    Directory of Open Access Journals (Sweden)

    Bonavetti, V. L.

    2014-09-01

    Full Text Available This paper analyses the influence of portland cement replacement by silica fume (up to 10% and/or granulated blast furnace slag (up to 70% on the hydration cement (XRD, heat of hydration, non evaporable water content and calcium hydroxide content curing under sealed conditions and their effect on the mechanical strength. The obtained results indicate that binary cements containing silica fume and ternary cements there was a significant increase of hydration rate at early age. At later ages, most of studied cements have an equivalent or greater strength that those obtained in the plain portland cement.En este trabajo se analiza la influencia de la incorporación al cemento portland de humo de sílice (hasta 10% y/o escoria granulada de alto horno (hasta 70% sobre la hidratación (DRX, calor de hidratación, contenido de agua no evaporable y de hidróxido de calcio, bajo condiciones de curado sellado y su incidencia sobre la resistencia mecánica. Los resultados obtenidos indican que en los cementos binarios con humo de sílice y en los cementos ternarios se produce un importante aumento de la velocidad de hidratación en las primeras edades, mientras que a edades más avanzadas la mayor parte del dominio estudiado alcanza o supera la resistencia obtenida por el cemento portland sin adición.

  6. Effects of colemanite waste, coal bottom ash, and fly ash on the properties of cement

    Energy Technology Data Exchange (ETDEWEB)

    Kula, I.; Olgun, A.; Erdogan, Y.; Sevinc, V. [Celal Bayar University, Manisa (Turkey)

    2001-03-01

    The physical and chemical properties of colemanite ore waste from concentrator, coal bottom ash, fly ash, cement+ash mixtures, cement+colemanite ore waste, and their effects on the mechanical properties of concrete were investigated. These materials with different proportion were substituted with Portland cement. Physical properties such as setting time, volume expansion, and compressive strength were determined and compared to reference mixture and Turkish standards (TS). The results showed that cement replacement materials had clear effects on the mechanical properties. The use of fly ash and bottom ash even at the concentration of 25% showed either comparable or better result compared to reference mixture. Although replacement of Portland cement by 9 wt.% of colemanite ore waste causes reduction in the compressive strength, the values obtained are within the limit of TS. As a result, colemanite ore waste, fly ash, and bottom ash may be used as cementitious materials.

  7. Sustainable production of blended cement in Pakistan through addition of natural pozzolana

    Directory of Open Access Journals (Sweden)

    Ahmad Muhammad Imran

    2016-01-01

    Full Text Available In this work pozzolana deposits of district Swabi, Pakistan were investigated for partial substitution of Portland cement along with limestone filler. The cement samples were mixed in different proportions and tested for compressive strength at 7 and 28 days. The strength activity index (SAI for 10 % pozzolana, and 5% limestone blend at 7 and 28 days was 75.5% and 85.0% satisfying the minimum SAI limit of ASTM C618. Twenty two percents natural pozzolana and five percents limestone were interground with clinker and gypsum in a laboratory ball mill to compare the power consumption with ordinary Portland cement (OPC (95% clinker and 5% gypsum. The ternary blended cement took less time to reach to the same fineness level as OPC due to soft pozzolana and high grade lime stone indicating that intergrinding may reduce overall power consumption. Blended cement production using natural pozzolana and limestone may reduce the energy consumption and green house gas emissions.

  8. Effect of metakaolin on strength and efflorescence quantity of cement-based composites.

    Science.gov (United States)

    Weng, Tsai-Lung; Lin, Wei-Ting; Cheng, An

    2013-01-01

    This study investigated the basic mechanical and microscopic properties of cement produced with metakaolin and quantified the production of residual white efflorescence. Cement mortar was produced at various replacement ratios of metakaolin (0, 5, 10, 15, 20, and 25% by weight of cement) and exposed to various environments. Compressive strength and efflorescence quantify (using Matrix Laboratory image analysis and the curettage method), scanning electron microscopy, and X-ray diffraction analysis were reported in this study. Specimens with metakaolin as a replacement for Portland cement present higher compressive strength and greater resistance to efflorescence; however, the addition of more than 20% metakaolin has a detrimental effect on strength and efflorescence. This may be explained by the microstructure and hydration products. The quantity of efflorescence determined using MATLAB image analysis is close to the result obtained using the curettage method. The results demonstrate the best effectiveness of replacing Portland cement with metakaolin at a 15% replacement ratio by weight.

  9. Effect of Lime on Mechanical and Durability Properties of Blended Cement Based Concrete

    Science.gov (United States)

    Acharya, Prasanna Kumar; Patro, Sanjaya Kumar; Moharana, Narayana C.

    2016-06-01

    This work presents the results of experimental investigations performed to evaluate the effect of lime on mechanical and durability properties of concrete mixtures made with blended cement like Portland Slag Cement (PSC) and Portland Pozzolana Cement (PPC) with lime content of 0, 5, 7 and 10 %. Test result indicated that inclusion of hydraulic lime on replacement of cement up to 7 % increases compressive strength of concrete made with both PSC and PPC. Flexural strength increased with lime content. Highest flexural strength is reported at 7 % lime content for both PSC and PPC. Workability is observed to decrease with lime addition which could be compensated with introduction of super plasticizer. Acid and sulphate resistance increase slightly up to 7 % of lime addition and is found to decrease with further addition of lime. Lime addition up to 10 % does not affect the soundness of blended cements like PSC and PPC.

  10. Coagulated silica - a-SiO2 admixture in cement paste

    Science.gov (United States)

    Pokorný, Jaroslav; Pavlíková, Milena; Záleská, Martina; Rovnaníková, Pavla; Pavlík, Zbyšek

    2016-07-01

    Amorphous silica (a-SiO2) in fine-grained form possesses a high pozzolanic activity which makes it a valuable component of blended binders in concrete production. The origin of a-SiO2 applied in cement-based composites is very diverse. SiO2 in amorphous form is present in various amounts in quite a few supplementary cementing materials (SCMs) being used as partial replacement of Portland cement. In this work, the applicability of a commercially produced coagulated silica powder as a partial replacement of Portland cement in cement paste mix design is investigated. Portland cement CEM I 42.5R produced according to the EU standard EN 197-1 is used as a reference binder. Coagulated silica is applied in dosages of 5 and 10 % by mass of cement. The water/binder ratio is kept constant in all the studied pastes. For the applied silica, specific surface area, density, loss on ignition, pozzolanic activity, chemical composition, and SiO2 amorphous phase content are determined. For the developed pastes on the basis of cement-silica blended binder, basic physical properties as bulk density, matrix density, and total open porosity are accessed. Pore size distribution is determined using MIP analysis. Initial and final setting times of fresh mixtures are measured by automatic Vicat apparatus. Effect of silica admixture on mechanical resistivity is evaluated using compressive strength, bending strength, and dynamic Young's modulus measurement. The obtained data gives evidence of a decreased workability of paste mixtures with silica, whereas the setting process is accelerated. On the other hand, reaction activity of silica with Portland cement minerals results in a slight decrease of porosity and improvement of mechanical resistivity of cement pastes containing a-SiO2.

  11. Pore structure in blended cement pastes

    DEFF Research Database (Denmark)

    Canut, Mariana Moreira Cavalcanti

    Supplementary cementitious materials (SCMs), such as slag and fly ash, are increasingly used as a substitute for Portland cement in the interests of improvement of engineering properties and sustainability of concrete. According to studies improvement of engineering properties can be explained...... supplement each other. Cement pastes (w/b=0.4) with and without slag and fly ash cured at two moisture (sealed and saturated) and temperature (20 and 55ºC) conditions were used to investigate the combined impact of SCMs addition and curing on the pore structure of pastes cured up to two years. Also...... volume and threshold pore size were found when comparing with plain cement paste at the same curing conditions. The porosity methods MIP, LTC and SEM have been shown to be suitable to characterise pore parameters of the pastes. MIP is a simple and fast method which covers a large range of pore sizes...

  12. Development of fluorapatite cement for dental enamel defects repair.

    Science.gov (United States)

    Wei, Jie; Wang, Jiecheng; Shan, Wenpeng; Liu, Xiaochen; Ma, Jian; Liu, Changsheng; Fang, Jing; Wei, Shicheng

    2011-06-01

    In order to restore the badly carious lesion of human dental enamel, a crystalline paste of fluoride substituted apatite cement was synthesized by using the mixture of tetracalcium phosphate (TTCP), dicalcium phosphate anhydrous (DCPA) and ammonium fluoride. The apatite cement paste could be directly filled into the enamel defects (cavities) to repair damaged dental enamel. The results indicated that the hardened cement was fluorapatite [Ca(10)(PO(4))(6)F(2), FA] with calcium to phosphorus atom molar ratio (Ca/P) of 1.67 and Ca/F ratio of 5. The solubility of FA cement in Tris-HCl solution (pH = 5) was slightly lower than the natural enamel, indicating the FA cement was much insensitive to the weakly acidic solutions. The FA cement was tightly combined with the enamel surface, and there was no obvious difference of the hardness between the FA cement and natural enamel. The extracts of FA cement caused no cytotoxicity on L929 cells, which satisfied the relevant criterion on dental biomaterials, revealing good cytocompatibility. In addition, the results showed that the FA cement had good mechanical strength, hydrophilicity, and anti-bacterial adhesion properties. The study suggested that using FA cement was simple and promising approach to effectively and conveniently restore enamel defects.

  13. Development of an Improved Cement for Geothermal Wells

    Energy Technology Data Exchange (ETDEWEB)

    Trabits, George [Trabits Group, LLC, Wasilla, AK (United States)

    2015-04-20

    After an oil, gas, or geothermal production well has been drilled, the well must be stabilized with a casing (sections of steel pipe that are joined together) in order to prevent the walls of the well from collapsing. The gap between the casing and the walls of the well is filled with cement, which locks the casing into place. The casing and cementing of geothermal wells is complicated by the harsh conditions of high temperature, high pressure, and a chemical environment (brines with high concentrations of carbon dioxide and sulfuric acid) that degrades conventional Portland cement. During the 1990s and early 2000s, the U.S. Department of Energy’s Geothermal Technologies Office (GTO) provided support for the development of fly-ash-modified calcium aluminate phosphate (CaP) cement, which offers improved resistance to degradation compared with conventional cement. However, the use of CaP cements involves some operational constraints that can increase the cost and complexity of well cementing. In some cases, CaP cements are incompatible with chemical additives that are commonly used to adjust cement setting time. Care must also be taken to ensure that CaP cements do not become contaminated with leftover conventional cement in pumping equipment used in conventional well cementing. With assistance from GTO, Trabits Group, LLC has developed a zeolite-containing cement that performs well in harsh geothermal conditions (thermal stability at temperatures of up to 300°C and resistance to carbonation) and is easy to use (can be easily adjusted with additives and eliminates the need to “sterilize” pumping equipment as with CaP cements). This combination of properties reduces the complexity/cost of well cementing, which will help enable the widespread development of geothermal energy in the United States.

  14. Structure and Property Characterization of Oyster Shell Cementing Material

    Institute of Scientific and Technical Information of China (English)

    钟彬杨; 周强; 单昌锋; 于岩

    2012-01-01

    Oyster shell powder was used as the admixture of ordinary portland cement.The effects of different addition amounts and grinding ways on the strength and stability of cement mortar were discussed and proper addition amount of oyster shell powder was determined.The structure and property changes of cementing samples with different oyster shell powder contents were tested by XRD and SEM means.The results revealed that compressive and rupture strengths of the sample with 10% oyster shell powder was close to those of the original one without addition.Stability experiment showed that the sample prepared by pat method had smooth surface without crack and significant expansion or shrinkage after pre-curing and boiling,which indicated that cementing material dosed with oyster shell powder had fine stability.XRD and SEM observation showed that oyster shell independently exists in the cementing material.

  15. Influence of pore structure on compressive strength of cement mortar.

    Science.gov (United States)

    Zhao, Haitao; Xiao, Qi; Huang, Donghui; Zhang, Shiping

    2014-01-01

    This paper describes an experimental investigation into the pore structure of cement mortar using mercury porosimeter. Ordinary Portland cement, manufactured sand, and natural sand were used. The porosity of the manufactured sand mortar is higher than that of natural sand at the same mix proportion; on the contrary, the probable pore size and threshold radius of manufactured sand mortar are finer. Besides, the probable pore size and threshold radius increased with increasing water to cement ratio and sand to cement ratio. In addition, the existing models of pore size distribution of cement-based materials have been reviewed and compared with test results in this paper. Finally, the extended Bhattacharjee model was built to examine the relationship between compressive strength and pore structure.

  16. Gravity Data for the Greater Portland Area

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The gravity station data (1,522 records) were compiled by the Portland State University. This data base was received in August 1990. Principal gravity parameters...

  17. EnviroAtlas - Portland, OR - Block Groups

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset is the base layer for the Portland, OR EnviroAtlas area. The block groups are from the US Census Bureau and are included/excluded based on...

  18. A New Kind of Eco-Cement Made of Cement Kiln Dust and Granular Blast Furnace Slag

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A research project was conducted to manufacture eco-cement for sustainable development using cement kiln dust( CKD ) and granular blast furnace slag( GBFS ).In the project, the burning process and mineral compositions of CKD clinker were investigated.Dife rent mineralizers such as CaSO4 and CaF2 , sulfur and alkali content were considered.The strength of CKD and GBFS eco-cement were evaluated.The results indicate the CKD clinker can not only form ordinary cement clinker minerals such as C3 S, C2 S and C4 AF, but also form strength to the Portland cement grade 32.5 when blend proportion is properly applied.

  19. Sodium Picosulfate, Magnesium Oxide, and Anhydrous Citric Acid

    Science.gov (United States)

    Sodium picosulfate, magnesium oxide, and anhydrous citric acid combination powder is used to empty the colon (large ... clear view of the walls of the colon. Sodium picosulfate is in a class of medications called ...

  20. High-temperature cementing materials for completion of geothermal wells. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kalyoncu, R.S.; Snyder, M.J.

    1981-05-01

    Several portland cement types, oil well cements, and various additives and admixtures were evaluated during the course of development of a number of promising compositions suitable for geothermal applications. Among the cements and various materials considered were portland cement Types I, III, and V; oil well cement Classes G, H, and J; and additives such as silica flour, blast furnace slags, pozzolan, hydrated lime, perlite, and aluminum phosphate. Properties of interest in the study were thickening time, compressive strength, cement-to-metal bond strength, and effects of the cements on the corrosion of steel well casings. Testing procedures and property data obtained on a number of compositions are presented and discussed. Several cementing compositions comprised of Class J oil well cement, pozzolan, blast furnace slags, and silica flour were found to possess properties which appear to make them suitable for use in geothermal well completions. Five of the promising cementing compositions have been submitted to the National Bureau of Standards for additional testing.

  1. 低温施工用快硬水泥的配方及性能试验研究%Low-temperature construction with rapid hardening cement formulations and performance test study

    Institute of Scientific and Technical Information of China (English)

    莫富治; 肖展瑜

    2013-01-01

      通过试验确定了一种以硫铝酸盐水泥熟料为主要成分的低温施工用快硬水泥的配方,在5℃的低温环境下试验,结果表明该配方水泥不需添加任何外加剂,按普通混凝土常温施工方法进行施工养护,不需实施任何冬期施工措施,1d抗压强度可达拆除模板要求,后期强度能继续增长。该配方水泥在低温下正常快速硬化主要机理为:硅酸盐水泥熟料和生石灰能快速释放出Ca(OH)2,天然二水石膏能快速释放出CaSO4, Ca(OH)2和CaSO4与硫铝酸盐水泥熟料中的主要矿物4(CaO)・3(Al2O3)・SO3(无水硫铝酸钙)迅速反应生成大量的钙矾石,加上硫铝酸盐水泥低温水化硬化专用催化剂——亚硝酸钠的作用,水泥奖体快速硬化。天然硬石膏溶解速度比天然二水石膏缓慢,在天然二水石膏用尽之后与无水硫铝酸钙等继续发生水化反应,使水泥硬化体后期强度不断增长。%Determined a formula of which a sulfur aluminate cement clinker as the main ingredient and low temperature construction with rapid hardening cement by experiment. At 5 ° C low-temperature environment test, the results show that the formulation of cement don’t need to add any admixtures, Construction maintenance is used by Ordinary concrete construction method at room temperature, Don’t need to implement any winter construction measures, 1d compressive strength up to the removal of the template requirements and the late strength can continue to grow. The main mechanism of the formulation normal and rapid hardening cement at low temperatures:Portland cement clinker and quicklime rapid release of Ca (OH) 2, Natural dihydrate gypsum quick release CaSO4, Ca (OH) 2 and CaSO4 sulphoaluminate cement clinker mineral 4 (CaO) 3 (Al2O3) SO3 (anhydrous calcium sulphoaluminate) rapid responsegenerate large amounts of ettringite, Plus sulfur the aluminate cement hypothermia hydration hardened special catalyst-the role of sodium

  2. Influence of Blended Cements with Calcareous Fly Ash on Chloride Ion Migration and Carbonation Resistance of Concrete for Durable Structures

    Directory of Open Access Journals (Sweden)

    Michał A. Glinicki

    2016-01-01

    Full Text Available The objective of this paper is to examine the possible use of new blended cements containing calcareous fly ash in structural concrete, potentially adequate for structural elements of nuclear power plants. The investigation included five new cements made with different contents of non-clinker constituents: calcareous fly ash, siliceous fly ash, ground granulated blastfurnace slag, and a reference cement—ordinary Portland cement. The influence of innovative cements on the resistance of concrete to chloride and carbonation exposure was studied. Additionally, an evaluation of the microstructure was performed using optical microscopy on concrete thin sections. Test results revealed a substantial improvement of the resistance to chloride ion penetration into concrete containing blended cements. The resistance was higher for increased clinker replacement levels and increased with curing time. However, concrete made with blended cements exhibited higher depth of carbonation than the Portland cement concrete, except the Portland-fly ash cement with 14.3% of calcareous fly ash. The thin sections analysis confirmed the values of the carbonation depth obtained from the phenolphthalein test. Test results indicate the possible range of application for new cements containing calcareous fly ash.

  3. Assessment of the radiological impacts of utilizing coal combustion fly ash as main constituent in the production of cement.

    Science.gov (United States)

    Turhan, Seref; Arıkan, Ismail H; Köse, Abdullah; Varinlioğlu, Ahmet

    2011-06-01

    The purpose of this study is to assess potential radiological impacts of utilizing pulverized fly ash (PFA) as a constituent in ordinary Portland cement. For this purpose, the activity concentrations of (226)Ra, (232)Th, and (40)K in samples of PFA and Portland cement containing 15%, 20%, and 25% by mass PFA were measured using gamma-ray spectrometry with HPGe detector. The mean activity concentrations of (226)Ra, (232)Th, and (40)K were found as 366.6, 113.7, and 460.2 Bq kg( - 1), 94.2, 25.9, and 215.3 Bq kg( - 1), 113.7, 34.3, and 238.3 Bq kg( - 1), and 124.2, 41.8, and 279.3 Bq kg( - 1) for the examined samples of PFA, Portland cement with 15%, 20%, and 25% by mass PFA, respectively. Radiological parameters such as radium equivalent activity, external exposure index (activity concentration index), internal dose index (alpha index), indoor absorbed gamma dose rate, and the corresponding the annually effective dose were assessed for Portland cement samples containing three percentages (15%, 20%, and 25%) by mass PFA. The results of assessment show that all Portland cement samples are within the safe limits recommended for building materials for dwellings.

  4. Durability and compressive strength of blast furnace slag-based cement grout for special geotechnical applications

    Directory of Open Access Journals (Sweden)

    Ortega, J. M.

    2014-03-01

    Full Text Available Special foundations, most prominently micropiles and soil anchors, are frequently used in construction today. In Spain, the grout for these special technical applications is generally prepared with portland cement, although the codes and standards in place stipulate only the minimum compressive strength required, with no mention of cement type. Those texts also establish a range of acceptable water:cement ratios. In the present study, durability and compressive strength in cement grout prepared with blast furnace slag cement at different w/c ratios are characterised and compared to the findings for a reference portland cement grout. The results show that slag grout exhibits greater durability than the portland cement material and complies with the compressive strength requirements laid down in the respective codes.Actualmente es muy frecuente el empleo de cimentaciones especiales, entre las que destacan los micropilotes y los anclajes. En España, las lechadas de cemento para estos trabajos geotécnicos especiales se preparan habitualmente con cemento Portland, aunque las diferentes normativas al respecto no restringen el tipo de cemento a emplear, siempre que se alcance una determinada resistencia a compresión. Respecto a la dosificación de las lechadas, la normativa permite emplear diferentes relaciones agua/cemento dentro de un determinado rango. En vista de ello, en este trabajo se han caracterizado las propiedades de durabilidad y resistencia a compresión de lechadas de cemento preparadas con un cemento con escoria de alto horno y con diferentes relaciones a/c, tomando como referencia de comportamiento lechadas de cemento Portland. El uso de un cemento con escoria conlleva una mejora en la durabilidad de las lechadas, cumpliendo los requisitos de resistencia a compresión establecidos por la normativa.

  5. High-volume use of self-cementing spray dry absorber material for structural applications

    Science.gov (United States)

    Riley, Charles E.

    Spray dry absorber (SDA) material, or spray dryer ash, is a byproduct of energy generation by coal combustion and sulfur emissions controls. Like any resource, it ought to be used to its fullest potential offsetting as many of the negative environmental impacts of coal combustion as possible throughout its lifecycle. Its cementitious and pozzolanic properties suggest it be used to augment or replace another energy and emissions intensive product: Portland cement. There is excellent potential for spray dryer ash to be used beneficially in structural applications, which will offset CO2 emissions due to Portland cement production, divert landfill waste by further utilizing a plentiful coal combustion by-product, and create more durable and sustainable structures. The research into beneficial use applications for SDA material is relatively undeveloped and the material is highly underutilized. This dissertation explored a specific self-cementing spray dryer ash for use as a binder in structural materials. Strength and stiffness properties of hydrated spray dryer ash mortars were improved by chemical activation with Portland cement and reinforcement with polymer fibers from automobile tire recycling. Portland cement at additions of five percent of the cementitious material was found to function effectively as an activating agent for spray dryer ash and had a significant impact on the hardened properties. The recycled polymer fibers improved the ductility and toughness of the material in all cases and increased the compressive strength of weak matrix materials like the pure hydrated ash. The resulting hardened materials exhibited useful properties that were sufficient to suggest that they be used in structural applications such as concrete, masonry block, or as a hydraulic cement binder. While the long-term performance characteristics remain to be investigated, from an embodied-energy and carbon emissions standpoint the material investigated here is far superior to

  6. Blended Cements Produced With Synthetic Zeolite Made from Industrial By-Product

    Directory of Open Access Journals (Sweden)

    Vitoldas Vaitkevičius

    2015-03-01

    Full Text Available Zeolites are appropriate supplementary cementitious materials in cement and concrete industry. In the present work synthetic zeolites was used like supplementary material in hardened cement paste and some properties as well as its influence on Portland cement hydration was determinate. X-ray powder diffraction, scanning electronic microscopy and energy-dispersive X-ray spectroscopy, FTIR spectroscopy were used as investigation methods. The compressive strength of hardened cement paste was measured at day 3, 28 and 60. The instrumental analysis showed that zeolite A(Na dominates and unreacted Al(OH3 remains in investigated synthetics zeolites, made from thermal and mechanical treated AlF3 production waste. The Chapelle test showed that both zeolites have good pozzolanic properties. The samples compressive strength remained close to the control samples compressive strength, reducing the amount of Portland cement, i.e., changing it by zeolite. After 60 days, the compressive strength was the best in the samples where 5% of Portland cement was replaced by the 2-zeolite. The compressive strength of the samples increased by 9 % compared with control samples. This research provides a real opportunity to save cement thus disposing the waste.DOI: http://dx.doi.org/10.5755/j01.ms.21.1.5635

  7. Early and late hydration of supersulphated cements of blast furnace slag with fluorgypsum

    Directory of Open Access Journals (Sweden)

    Bazaldúa-Medellín, M. E.

    2015-03-01

    Full Text Available The hydration, strength development and composition of hydration products of supersulphated cements were characterized from the first 48 hours up to 360 days. Two compositions of 80% Blast furnace slag, 10–15% Fluorgypsum and 10–5% Portland cement were cured in dry and wet conditions. The main hydration products were ettringite and C-S-H since the first hours and up to 360 days as evidenced by X-ray diffraction, thermal analysis and electron microscopy. The strength was favored by higher fluorgypsum contents and lower Portland cement contents. These cements generated heats of hydration of 40–57 KJ/Kg after 28 hours, which are lower than portland cement.Se realizó la caracterización de la hidratación, desarrollo de resistencia y la composición de los productos de hidratación de los cementos supersulfatados durante las primeras 48 horas y hasta 360 días. Se estudiaron dos composiciones de 80% de Escoria de alto horno, 10–15% de Fluoryeso y 10–5% de Cemento portland, se curaron en condiciones secas y húmedas. Los principales productos de hidratación fueron etringita y C-S-H desde las primeras horas y hasta 360 días, como se evidenció por difracción de rayos X, análisis térmico y microscopía electrónica de barrido. La resistencia se favoreció con mayor contenido de fluoryeso y bajos contenidos de cemento portland. Estos cementos generaron calores de hidratación de 40–57 KJ/Kg después de 28 horas, los cuales resultan más bajos que los generados por el cemento portland.

  8. The Impact of Coal Combustion Fly Ash Used as a Supplemental Cementitious Material on the Leaching of Constituents from Cements and Concretes

    Science.gov (United States)

    The objective of this report is to compare the leaching of portland cement-based materials that have been prepared with and without coal combustion fly ash to illustrate whether there is evidence that the use of fly ash in cement and concrete products may result in increased leac...

  9. Effect of Calcium Aluminate Cement Variety on the Hydration of Portland Cement in Blended System

    Institute of Scientific and Technical Information of China (English)

    XU Linglin; WANG Peiming; Geert DE SCHUTTER; WU Guangming

    2014-01-01

    Two kinds of CACs with different monocalcium aluminate (CA) contents were used in the PC/CAC (PAC) mixtures. Effects of CA and CACs on the properties of PAC were analyzed by setting times and the compressive strength tests, and also by means of calorimetry, XRD, DTA-TG and ESEM. The experimental results show that the compressive strength of the PAC mortars decreases with increasing content of CAC while it declines sharply with a higher content of CA in CAC. Compared with neat PC paste, the content of calcium hydroxide in hydrates of PAC paste decreases significantly, and the hydration time of PC is prominently prolonged. Additionally, the higher the content of CA in CAC, the more obviously the hydration of PC is delayed, confirming that the CA phase in CAC plays an important role in the delay of PC hydration.

  10. Recycling of red muds with the extraction of metals and special additions to cement

    Science.gov (United States)

    Zinoveev, D. V.; Diubanov, V. G.; Shutova, A. V.; Ziniaeva, M. V.

    2015-01-01

    The liquid-phase reduction of iron oxides from red mud is experimentally studied. It is shown that, in addition to a metal, a slag suitable for utilization in the construction industry can be produced as a result of pyrometallurgical processing of red mud. Portland cement is shown to be produced from this slag with mineral additions and a high-aluminate expansion addition to cement.

  11. On the effect of mixing on property development of cement pastes

    DEFF Research Database (Denmark)

    Geiker, Mette Rica; Bøhm, Anja; Kjeldsen, Ane Mette

    2006-01-01

    The method of mixing may affect the degree of agglomeration of particles in cement-based materials and thus the properties of the materials in their fresh, hardening, and hardened state. Paste (w/c=0.35) of white Portland cement with and without 10% silica fume and 0.65% superplasticizer were mixed...... was observed. The effect of mixing on development of hydration was not reflected in the resistance to migration of chloride ions in 28 days old samples....

  12. IR spectroscopy of sulphates in clinkers and cements

    Directory of Open Access Journals (Sweden)

    Vázquez, T.

    1986-03-01

    Full Text Available Infrared spectroscopy is a very useful technique in Cement Chemistry. This work is devoted to the study of a large number of sulphates that should have an incidence in false set phenomena, and they are qualitative and semi-quantitatlvely studied when they are in some degree in the clinker or in the portland cement.

    La espectroscopía infrarroja es una técnica de gran utilidad en la Química del Cemento. En el presente trabajo se aplica al estudio de numerosos sulfatos que pueden tener incidencia en el fenómeno de falso fraguado, y se estudian cualitativa y semicuantitativamente cuando forman parte del clinker o cemento portland.

  13. Nanostructure of Calcium Silicate Hydrates in Cements

    KAUST Repository

    Skinner, L. B.

    2010-05-11

    Calcium silicate hydrate (CSH) is the major volume phase in the matrix of Portland cement concrete. Total x-ray scattering measurements with synchrotron x rays on synthetic CSH(I) shows nanocrystalline ordering with a particle diameter of 3.5(5) nm, similar to a size-broadened 1.1 nm tobermorite crystal structure. The CSH component in hydrated tricalcium silicate is found to be similar to CSH(I). Only a slight bend and additional disorder within the CaO sheets is required to explain its nanocrystalline structure. © 2010 The American Physical Society.

  14. Properties and Acceleration Mechanism of Cement Mortar Added with Low Alkaline Liquid State Setting Accelerator

    Institute of Scientific and Technical Information of China (English)

    PAN Zhihua; WANG Xuebing; LIU Weiqing

    2014-01-01

    Low alkaline liquid state setting accelerator(LSA) for Portland cement was prepared in laboratory from aqueous solution of several inorganic sulfate salts and some organic chemical substances. Properties of cement with addition of LSA relating to its setting time and strength development as well as its resistance to sulfate attack for short and long term exposure were experimentally examined. The experimental results showed that 5%-7%addition of LSA significantly accelerated the initial and final setting of Portland cement in the presence or absence of the blending of mineral admixtures, the initial and final setting time being less than 3 min and 6 min respectively. Meanwhile, the early 1 day curing age compressive strength increased remarkably by 20%, while the late 28th day curing age compressive strength remained almost unchanged as compared with that of the reference accelerator free cement mortar specimen. Furthermore, mortar specimens of cement added with LSA and exposed to 5%Na2SO4 solution showed their excellent resistance to sulfate attack, with their short and long term curing age resistance coefficient to sulfate attack being around 1.04 to 1.17, all larger than 1.0. XRD analysis on hardened cement paste specimens at very early curing ages of several minutes disclosed the existence of more ettringite in specimens added with LSA than that of the reference specimens, meanwhile SEM observation also revealed the existence of well crystallized ettringite at very early hydration stage, suggesting that the accelerated setting of Portland cement can be attributed to the early and rapid formation of ettringite over the whole cement paste matrix due to the introduction of LSA. MIP measurement revealed that hardened cement paste specimens with the addition of LSA presented less medium diameter pores, more proportion of small pores and less proportion of large capillary pores, which is in a very good coincidence with the improvement of strength development of

  15. Preparation of calcium sulphoaluminate cement using fertiliser plant wastes.

    Science.gov (United States)

    Singh, Maneesh; Kapur, P C; Pradip

    2008-08-30

    Phosphochalks from fertiliser plants contain significant amount of calcium sulphate along with P(2)O(5) and fluorine. The presence of these impurities makes them unsuitable for most applications and, hence its availability in millions of tons. We demonstrate that it is possible to prepare calcium sulphoaluminate-aluminoferrite based special cements having strength values comparable to ordinary Portland cement (OPC) using these waste chalks. Such cements are insensitive to the presence of impurities in the raw mixture, clinker at low temperatures (1,230 degrees C) and the clinkers produced are soft and friable. An empirical technique has been developed to predict the phase composition of the clinkers given the chemical composition of the starting raw mixture. The proposed low temperature clinkering route appears to be a promising method for converting waste phosphochalks into construction grade cements.

  16. Preparation of anhydrous lanthanum bromide for scintillation crystal growth

    Institute of Scientific and Technical Information of China (English)

    ZHANG Tong; LI Hongwei; ZHAO Chunlei; YU Jinqiu; HU Yunsheng; CUI Lei; HE Huaqiang

    2012-01-01

    This paper reported an efficient and economical method for preparation of anhydrous LaBr3 for scintillation crystal growth.High purity anhydrous LaBr3 powders in large quantities were successfully obtained by stepped dehydration of LaBr3·7H2O using NH4Br as additive.Experiments revealed that adding proper amount of NH4Br could effectively restrain the hydrolysis of LaBr3 during dehydration and thus decreased the yield of deleterious impurity of LaOBr.Optimum preparation conditions,including the amount of NH4Br in use,the dehydration temperature and atmosphere,were investigated by DTA/TG and water/oxygen analysis.The Raman characterization of the as-prepared anhydrous LaBr3 was also presented.

  17. DEVELOPMENT OF HYDRAULIC GYPSUM THAT CONTAINS CEMENTS THAT HAVE SULPHATED CLINKER PHASES

    Directory of Open Access Journals (Sweden)

    Mikheenkov Mikhail Arkad'evich

    2012-10-01

    Full Text Available In the article, the authors consider the feasibility of development of water-hardened gypsum that is capable of hardening in the water. The gypsum in question is made of the gypsum binding material, sulphated Portland cement, and granulated blast-furnace slag. The gypsum developed hereunder has a softening coefficient over 1 while the building gypsum content exceeds 75 %.

  18. Porosity prediction of calcium phosphate cements based on chemical composition.

    Science.gov (United States)

    Öhman, Caroline; Unosson, Johanna; Carlsson, Elin; Ginebra, Maria Pau; Persson, Cecilia; Engqvist, Håkan

    2015-07-01

    The porosity of calcium phosphate cements has an impact on several important parameters, such as strength, resorbability and bioactivity. A model to predict the porosity for biomedical cements would hence be a useful tool. At the moment such a model only exists for Portland cements. The aim of this study was to develop and validate a first porosity prediction model for calcium phosphate cements. On the basis of chemical reaction, molar weight and density of components, a volume-based model was developed and validated using calcium phosphate cement as model material. 60 mol% β-tricalcium phosphate and 40 mol% monocalcium phosphate monohydrate were mixed with deionized water, at different liquid-to-powder ratios. Samples were set for 24 h at 37°C and 100% relative humidity. Thereafter, samples were dried either under vacuum at room temperature for 24 h or in air at 37 °C for 7 days. Porosity and phase composition were determined. It was found that the two drying protocols led to the formation of brushite and monetite, respectively. The model was found to predict well the experimental values and also data reported in the literature for apatite cements, as deduced from the small absolute average residual errors (brushite, monetite and apatite cements. The model gives a good estimate of the final porosity and has the potential to be used as a porosity prediction tool in the biomedical cement field.

  19. Full phase analysis of portland clinker by penetrating synchrotron powder diffraction.

    Science.gov (United States)

    de la Torre, A G; Cabeza, A; Calvente, A; Bruque, S; Aranda, M A

    2001-01-15

    Fabrication of portland cements commonly depends on X-ray fluorescence (XRF), which measures the elemental compositions. XRF is used to adjust the raw material proportions and to control the process conditions. However, to predict the mechanical strength of the resulting concrete, it is essential to know the phase composition which is, so far, indirectly inferred by the Bogue method. Here, we report a phase analysis of an industrial portland clinker containing six crystalline phases, Ca3SiO5, Ca2SiO4, Ca4Al2Fe2O10, Ca3Al2O6, NaK3(SO4)2, and CaO, by Rietveld refinement of synchrotron X-ray powder diffraction data (lambda = 0.442377 A). Even the minor component, CaO 0.45(2)%, was readily analyzed. We have also carried out a phase study of the same clinker with laboratory X-rays to characterize the changes in the detection limit and errors. Furthermore, by adding a suitable crystalline standard to the same clinker, we have determined the overall amorphous phase content. The procedure established for this state-of-the-art phase analysis shows the high precision that can be achieved by using penetrating X-rays, which is of interest not only in cement chemistry but in other industrially important multiphase systems such as slags, superalloys, or catalysts.

  20. Portland, Oregon: Solar in Action (Brochure)

    Energy Technology Data Exchange (ETDEWEB)

    2011-10-01

    This brochure provides an overview of the challenges and successes of Portland, OR, a 2007 Solar America City awardee, on the path toward becoming a solar-powered community. Accomplishments, case studies, key lessons learned, and local resource information are given.

  1. How Valid Are the Portland Baseline Essays?

    Science.gov (United States)

    Martel, Erich

    1991-01-01

    Portland, Oregon's "African-American Baseline Essays," widely used in creating multicultural curricula, inaccurately depicts ancient Egyptians as black people and Olmec civilization as derived from African influences. The authors advance racial theories long abandoned by mainline Africa scholars, attribute mystical powers to pyramids,…

  2. Research of magnesium phosphosilicate cement

    Science.gov (United States)

    Ding, Zhu

    Magnesium phosphosilicate cement (MPSC) is a novel phosphate bonded cement, which consists mainly of magnesia, phosphate and silicate minerals. The traditional magnesium phosphate cements (MPCs) usually composed by ammonium phosphate, and gaseous ammonia will emit during mixing and in service. There is no noxious ammonia released from MPSC, furthermore, it can recycle a large volume of the non-hazardous waste. The goal of this research is to investigate the composition, reaction products, reaction mechanism, microstructure, properties, durability and applications of the MPSC. MPSC sets rapidly and has high early strength. It reacts better with solid industrial waste when compared to Portland cement. Many solid industrial wastes, such as fly ash, steel slag, coal gangue, red coal gangue, red mud, barium-bearing slag, copper slag, silica fume, and ground granulated blast furnace slag, have been used as the main component (40% by weight) in MPSC. The research has found that these aluminosilicate (or ironsilicate, or calciumsilicate) minerals with an amorphous or glass structure can enhance the performance of MPSC. The disorganized internal structure of amorphous materials may make it possess higher reactivity compared to the crystalline phases. Chemical reaction between phosphate and these minerals may form an amorphous gel, which is favorable to the cementing. Borax, boric acid and sodium tripolyphosphate have been used as retardants in the MPSC system. It is found that boric acid has a higher retarding effect on the setting of cement, than borax does. However, sodium polyphosphate accelerates the reaction of MPSC. The hydration of MPSC is exothermic reaction. The heat evolution may prompt hydrates formation, and shorten the setting process. Modern materials characterization techniques, XRD, DSC, TG-DTA FTIR, XPS, MAS-NMR, SEM, TEM, MIP, etc. were used to analyze the phase composition, micro morphology, and microstructure of hardened MPSC. The main hydration product

  3. Response of a PGNAA setup for pozzolan-based cement concrete specimens

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)], E-mail: aanaqvi@kfupm.edu.sa; Garwan, M.A. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Maslehuddin, M. [Center for Engineering Research, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Nagadi, M.M. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Al-Amoudi, O.S.B. [Department of Civil Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Raashid, M. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

    2010-04-15

    Pozzolanic materials are added to Portland cement concrete to increase its durability, particularly corrosion-resistance. In this study the elemental composition of a pozzolanic cement concrete was measured non-destructively utilizing an accelerator-based Prompt Gamma Ray Neutron Activation Analysis (PGNAA) setup. The optimum size of the pozzolanic cement concrete specimen was obtained through Monte Carlo simulations. The simulation results were experimentally verified through the {gamma}-ray yield measurement from the pozzolanic cement concrete specimens as a function of their radii. The concentration of the pozzolanic material in the cement concrete specimens was evaluated by measuring {gamma}-ray yield for calcium and iron from pozzolanic cement concrete specimens containing 5-80 wt% pozzolan. A good agreement was noted between the experimental values and the Monte Carlo simulation results, indicating an excellent response of the KFUPM accelerator-based PGNAA setup for pozzolan based concrete.

  4. Response of a PGNAA setup for pozzolan-based cement concrete specimens.

    Science.gov (United States)

    Naqvi, A A; Garwan, M A; Maslehuddin, M; Nagadi, M M; Al-Amoudi, O S B; Raashid, M

    2010-01-01

    Pozzolanic materials are added to Portland cement concrete to increase its durability, particularly corrosion-resistance. In this study the elemental composition of a pozzolanic cement concrete was measured non-destructively utilizing an accelerator-based Prompt Gamma Ray Neutron Activation Analysis (PGNAA) setup. The optimum size of the pozzolanic cement concrete specimen was obtained through Monte Carlo simulations. The simulation results were experimentally verified through the gamma-ray yield measurement from the pozzolanic cement concrete specimens as a function of their radii. The concentration of the pozzolanic material in the cement concrete specimens was evaluated by measuring gamma-ray yield for calcium and iron from pozzolanic cement concrete specimens containing 5-80 wt% pozzolan. A good agreement was noted between the experimental values and the Monte Carlo simulation results, indicating an excellent response of the KFUPM accelerator-based PGNAA setup for pozzolan based concrete.

  5. Estimating the chloride transport in cement paste

    Directory of Open Access Journals (Sweden)

    Princigallo, A.

    2012-06-01

    Full Text Available A method was developed to measure the diffusion coefficient of chloride ions in cement paste based on an analytical solution to Fick’s 2nd law in a cylindrical coordinate system. This natural method yielded diffusivity results within as little as a month. Testing time was reduced by exploiting the three-dimensional inward flux in the specimen. In an attempt to determine the saturation concentration, dense portland cement pastes were exposed to a concentrated chloride solution. The method proved to be useful for exploring cement hydration-induced changes in the diffusion coefficient of cement paste.

    Se ha desarrollado un método para medir el coeficiente de difusión de los iones cloruro en la pasta de cemento, partiendo de una aplicación analítica de la segunda ley de Fick en un sistema de coordinadas cilíndrico. Este método, que es natural, demostró ser capaz de producir resultados de difusividad en tan solo un mes. Se consiguió reducir el tiempo de ensayo mediante el aprovechamiento de la tridimensionalidad del flujo desde el exterior al interior de la probeta. A fin de determinar la concentración de saturación, se sometieron las pastas de cemento Portland a una disolución de cloruros concentrada. Este método resultó ser útil en el estudio de los cambios del coeficiente de difusión de la pasta de cemento provocados por las reacciones de hidratación que tienen lugar en esta.

  6. SODIUM CITRATE INFLUENCE ON FORMATION OF CEMENT STONE IN THE ALUMINOUS BINDER

    Directory of Open Access Journals (Sweden)

    S. N. Leonovich

    2016-01-01

    Full Text Available The paper deals with the effect of sodium citrate on the formation of a cement stone in the aluminous binder. Formation of cement stone framework in cement hydraulic binder is accompanied with complicated physical and chemical processes of interphase interactions and dispersion, these processes are predicated on qualitative and quantitative composition of the cement mortar, continuous changes in its properties from preparation stage till curing. Addition of sodium citrate to tempering water enhances hydration of both Portland cement and calcium aluminate cement. Process pertaining to an increase of cement hydration rate is considered as a consequence of destruction in surface formations and exclusion of damping effect in respect of hydration rate and hydrolysis of products resulted from interaction of clinker material with tempering. It has been established that sodium citrate makes it possible to control processes of hydration, hydrolysis, binding and curing for cement mass. High degree of hydration of aluminous cement in the presence of sodium citrate provides fast binding and curing of binder, low porosity and rather high compression breaking strength of cement stone for all curing stages. An increase in concentration of sodium citrate in cement mixture up to 10 % of the cement mass exerts an influence not only on the process of cement mortar liquefaction, reduction of time for cement mass setting and hardening but also increases compression strength of cement stone. An analysis of the structure for cleavage surface of cement stone gives ground to declare that the addition of sodium citrate provides cement stone sealing and reduces its water absorption.

  7. Process for the production of sodium carbonate anhydrate

    NARCIS (Netherlands)

    Oosterhof, H.; Van Rosmalen, G.M.; Witkamp, G.J.; De Graauw, J.

    2000-01-01

    The invention is directed to a process for the production of sodium carbonate-anhydrate having a bulk density of at least 800 kg/m<3>, said process comprising: providing a suspension of solid sodium carbonate and/or solid sodium bicarbonate and/or solid double salts at least comprising one of

  8. Cements with low Clinker Content

    Science.gov (United States)

    García-Lodeiro, I.; Fernández-Jiménez, A.; Palomo, A.

    2015-11-01

    Hybrid alkaline cements are multi-component systems containing a high percentage of mineral additions (fly ash, blast furnace slag), low proportions (clinker and scarce amounts of alkaline activators. The substantially lower amount of clinker needed to manufacture these binders in comparison to ordinary Portland cement is both economically and ecologically beneficial. Their enormous versatility in terms of the raw materials used has made them the object of considerable interest. The present study explored the mechanical strength of binary blends mixes; B1= 20% clinker (CK) + 80% fly ash (FA) and B2=20% clinker + 80% blast furnace slag (BFS), both hydrated in the presence and absence of an alkaline activator specifically designed for this purpose. The use of the activator enhanced the development of early age strength considerably. All the hydrated matrices were characterised with XRD, SEM/EDX and (29Si and 27Al) NMR. The use of the alkaline activator generated reaction products consisting primarily of a mix of gels ((N,C)-A-S-H and C-A-S-H) whose respective proportions were found to depend upon system composition and initial reactivity.

  9. 7th NCB international seminar on cement and building materials. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    Topics covered include: mining and mine environment (including CO{sub 2} mitigation in cement concrete industries), and project engineering and management (in volume 1); productivity enhancement and process optimisation (upgrading/cost reduction, grinding/refractories, process optimisation and control, and maintenance) (in volume 2); plant environment and pollution control (including global climate change) performance of concrete, and Portland and blended cements (in volume 3); special cements and binders, total quality management and energy management (in volume 4); and supplementary papers in volume 5.

  10. Characterization of composite materials based on cement-ceramic powder blended binder

    Science.gov (United States)

    Kulovaná, Tereza; Pavlík, Zbyšek

    2016-06-01

    Characterization of newly developed composite mortars with incorporated ceramic powder coming from precise brick cutting as partial Portland cement replacement up to 40 mass% is presented in the paper. Fine ceramic powder belongs to the pozzolanic materials. Utilization of pozzolanic materials is accompanied by lower request on energy needed for Portland clinker production which generally results in lower production costs of blended binder and lower CO2 emission. In this paper, the ceramic powder is used in cement based mortar composition in amount of 8, 16, 24, 32, and 40 mass% of cement. Chemical composition of ceramic powder is analyzed by X-Ray Fluorescence and X-Ray Diffraction. The particle size distribution of ceramics is accessed on laser diffraction principle. For 28 days cured mortar samples, basic physical and mechanical properties are experimentally determined. The obtained results demonstrate that ceramic powder has potential to replace a part of Portland cement in composition of cement based composites and to reduce negative environmental impact of their production.

  11. 49 CFR 173.195 - Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution).

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Hydrogen cyanide, anhydrous, stabilized... Hazardous Materials Other Than Class 1 and Class 7 § 173.195 Hydrogen cyanide, anhydrous, stabilized (hydrocyanic acid, aqueous solution). (a) Hydrogen cyanide, anhydrous, stabilized, must be packed...

  12. 7 CFR 51.1178 - Maximum anhydrous citric acid permissible for corresponding total soluble solids.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Maximum anhydrous citric acid permissible for... Sinensis (l) Osbeck) § 51.1178 Maximum anhydrous citric acid permissible for corresponding total soluble solids. For determining the grade of juice, the maximum permissible anhydrous citric acid content...

  13. Hydrothermal Characteristics of Blended Cement Pastes Containing Silica Sand Using Cement Kiln Dust as an Activator

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The hydrothermal reactivity of silica sand was studied using cement kiln dust (CKD) as an activator in addition to the Portlandcement fraction of El-Karnak cement (a blend of ordinary Portland cement and ground sand). Autoclaved El-Karnak cementpastes were studied at pressures of 0.507, 1.013 and 1.520 MPa of saturated steam with respect to their compressive strength,kinetics of hydrothermal reaction and the phase composition of the formed hydrates. The role of CKD in affecting thephysicochemical and mechanical properties of El-Karnak cement pastes was studied by autoclaving of several pastes containing5, 7.5, 10 and 20% CKD at a pressure of 1.013 MPa of saturated steam. CKD was added either as a raw CKD (unwashed) orafter washing with water (washed CKD). The results of these physicochemical studies obtained could be related as much aspossible to the role of CKD (raw or washed) in affecting the hydrothermal reactivity of silica sand in El-Karnak cement pastes.

  14. Alite-ye'elimite cement: Synthesis and mineralogical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Suhua [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Materials Science and Engineering, Nanjing University of Technology, Nanjing 210009 (China); Snellings, Ruben [Laboratory of Construction Materials, Institute of Materials, Ecole Polytechnique Fédéral de Lausanne, Station 12, CH-1015 Ecublens (Switzerland); Li, Xuerun [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Materials Science and Engineering, Nanjing University of Technology, Nanjing 210009 (China); Shen, Xiaodong, E-mail: xdshen@njut.edu.cn [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Materials Science and Engineering, Nanjing University of Technology, Nanjing 210009 (China); Scrivener, Karen L. [Laboratory of Construction Materials, Institute of Materials, Ecole Polytechnique Fédéral de Lausanne, Station 12, CH-1015 Ecublens (Switzerland)

    2013-03-15

    Alite-ye'elimite cement is an alternative cement that combines desirable characteristics of calcium sulfoaluminate cements and Portland cement in that it shows improved strength development at early age while retaining high portlandite contents. The key problem in the clinkering process is to produce the alite-ye'elimite phase assemblage so that both phases can co-exist. In this study, a new synthesis method is proposed to achieve the coexistence of alite and ye'elimite consisting of a secondary heat treatment step at 1250 °C after regular Portland clinker firing at 1450 °C. Quantitative X-ray powder diffraction and electron microscopy were used to analyze the phase composition of clinker before and after the secondary heat treatment. The results show that ye'elimite develops during secondary heat treatment of calcium sulphate enriched clinker by reaction of C{sub 3}A and sulphate phases. Additional ferrite is formed as result of rejection of Fe originally in solid solution with C{sub 3}A during ye'elimite formation.

  15. Imaging wellbore cement degradation by carbon dioxide under geologic sequestration conditions using X-ray computed microtomography.

    Science.gov (United States)

    Jung, Hun Bok; Jansik, Danielle; Um, Wooyong

    2013-01-02

    X-ray microtomography (XMT), a nondestructive three-dimensional imaging technique, was applied to demonstrate its capability to visualize the mineralogical alteration and microstructure changes in hydrated Portland cement exposed to carbon dioxide under geologic sequestration conditions. Steel coupons and basalt fragments were added to the cement paste in order to simulate cement-steel and cement-rock interfaces. XMT image analysis showed the changes of material density and porosity in the degradation front (density: 1.98 g/cm(3), porosity: 40%) and the carbonated zone (density: 2.27 g/cm(3), porosity: 23%) after reaction with CO(2)-saturated water for 5 months compared to unaltered cement (density: 2.15 g/cm(3), porosity: 30%). Three-dimensional XMT imaging was capable of displaying spatially heterogeneous alteration in cement pores, calcium carbonate precipitation in cement cracks, and preferential cement alteration along the cement-steel and cement-rock interfaces. This result also indicates that the interface between cement and host rock or steel casing is likely more vulnerable to a CO(2) attack than the cement matrix in a wellbore environment. It is shown here that XMT imaging can potentially provide a new insight into the physical and chemical degradation of wellbore cement by CO(2) leakage.

  16. INFLUENCE OF POZZOLANA ON THE HYDRATION OF C4AF RICH CEMENT IN CHLORIDE ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    IRMANTAS BARAUSKAS

    2013-03-01

    Full Text Available This study investigated the influence of natural pozzolana - opoka additive on the hydration of C4AF rich cement and the effects of chloride ions on the hydrates formed. In the samples, 25 % (by weight of the sintered C4AF rich cement and OPC was replaced with pozzolana. The mixtures were hardened for 28 days in water, soaked in a saturated NaCl solution for 3 months at 20°C. It was estimated that under normal conditions, pozzolana additive accelerates the hydration of calcium silicates and initiates the formation of CO32- - AFm in the Brownmillerite rich cement. However, the hydration of Brownmillerite cement with opoka additive is still slower to compare with hydration of Portland cement. Also, opoka decreases total porosity and threshold pore diameter of Brownmillerite cement paste after two days of hydration. After 28 days of hydration threshold pore diameter became smaller even to compare with threshold pore diameter of Portland cement. Opoka additive promotes the formation of Friedel’s salt in Brownmillerite samples treated in saturated NaCl solution, because CO32-–AFm affected by saturated NaCl solution become unstable and takes part in reactions producing Friedel’s salt.

  17. Influence of various acids on the physico–mechanical properties of pozzolanic cement mortars

    Indian Academy of Sciences (India)

    S Türkel; B Felekoǧlu; S Dulluç

    2007-12-01

    Acidic attack represents a topic of increasing significance, owing to the spread of damages of concrete structures in both urban and industrial areas. Cement type is an important factor affecting performance of cement based materials in an aggressive environment. The goal of this study was to compare the acid resistance of a pozzolanic cement (CEM IV-A/32·5) with Portland cement (CEM I 32·5) that was made from the same clinker. For this purpose, 50 mm mortar cubes were prepared with two different kinds of cement according to TS EN 196-1. After 28 days of hardening, the samples were immersed into four different concentrations of hydrochloric, nitric and sulfuric acid solutions for a period of 120 days. The changes in weight loss and compressive strength values for each acid solution within the test period were recorded. The acid resistance of mortars made from Portland cement was better than the pozzolanic cement incorporated samples after 120 days of acid attack.

  18. A remark on nano-particle stability of cement C-S-H gel

    Science.gov (United States)

    Ficker, Tomáš; Len, Adél; Martišek, Dalibor

    2011-04-01

    Hydrated pastes of ordinary Portland cement prepared with different water-to-cement ratios were investigated by using the small-angle neutron scattering technique in the region of Q ∈ (0.0045, 0.11) Å-1. Samples of cement pastes were subjected to non-standard hydration conditions using a mix with D2O, low RH, and water-to-cement ratios spread over a very wide interval (0.4; 1.4). The investigation was focused on testing the structural stability of nano-metric particles in the cement C-S-H gel. Owing to the high structural stability of these nano-particles, their average diameter might be used as a microscopic parameter characterizing the nano-metric structure of C-S-H gels. The average diameter of the nano-particles of the studied ordinary Portland cement CEMI 42.5 R-SC was found to be close to the value of 4.2 nm and independent of the water-to-cement ratios.

  19. Composite cements containing natural pozzolan and granulated blast furnace slag

    Directory of Open Access Journals (Sweden)

    Irassar, E. F.

    2006-09-01

    Full Text Available For reasons of market demand and Portland cement production,the manufacture of cements with two or more separately ground additions to produce customized cements is becoming common practice.When pozzolan or slag content in this type of cements is high, however, the initial strength of the resulting product may be adversely impacted. This problem can be minimized by activating one or both of the replacement materials. The present study analyzes the effect of Portland cement additions such as physically activated natural pozzolan(up to 20% and/or granulated blast furnace slag (up to 35% on mortar flexural and compressive strength. The results show that higher strength is attained in ternary than binary cements. Initially (2 and 7 days, the highest compressive strengths are reached by mortars with up to 13% natural pozzolan and 5% slag, whereas at later ages mortars with larger proportions of additions are found to perform best.Debido a las exigencias del mercado y de la producción de cemento Portland, es cada vez más frecuente la elaboración de cementos con dos o más adiciones a partir de la molienda separada de sus constituyentes, dando origen a la formulación de los cementos a medida.Cuando el contenido de adiciones es alto, la utilización de puzolana y escoria en este tipo de cementos presenta la peculiaridad de disminuir la resistencia inicial del cemento resultante. Sin embargo, si algunas o ambas adiciones se activan, este problema puede minimizarse. En este trabajo se analiza la influencia de la incorporación al cemento Portland de puzolana natural (hasta 20% activada físicamente y/o escoria granulada de alto horno (hasta 35% sobre la resistencia a flexión y a compresión de morteros. Los resultados indican que los cementos ternarios presentan un mejor comportamiento resistente que los cementos binarios. Las máximas resistencias a compresión en las primeras edades (2 y 7 díasse alcanzan con hasta 13% de puzolana natural y 5% de

  20. A review of binders used in cemented paste tailings for underground and surface disposal practices.

    Science.gov (United States)

    Tariq, Amjad; Yanful, Ernest K

    2013-12-15

    Increased public awareness of environmental issues coupled with increasingly stringent environmental regulations pertaining to the disposal of sulphidic mine waste necessitates the mining industry to adopt more competent and efficient approaches to manage acid rock drainage. Cemented paste tailings (CPT) is an innovative form of amalgamated material currently available to the mining industry in developed countries. It is made usually from mill tailings mingled with a small amount of binder (customarily Portland cement) and water. The high cost associated with production and haulage of ordinary Portland cement and its alleged average performance as a sole binder in the long term (due to vulnerability to internal sulphate attack) have prompted users to appraise less expensive and technically efficient substitutes for mine tailings paste formulations. Generally, these binders include but are not limited to sulphate resistant cements, and/or as a partial replacement for Portland cement by artificial pozzolans, natural pozzolans, calcium sulphate substances and sodium silicates. The approach to designing environmentally efficient CPT is to ensure long-term stability and effective control over environmental contaminants through the use of composite binder systems with enhanced engineering properties to cater for inherit deficiencies in the individual constituents. The alkaline pore solution created by high free calcium rich cement kiln dust (CKD) (byproduct of cement manufacturing) is capable of disintegrating the solid glassy network of artificial pozzolans to produce reactive silicate and aluminate species when attacked by (OH(-)) ions. The augmented pozzolanic reactivity of CKD-slag and CKD-fly ash systems may produce resilient CPT. Since cemented paste comprising mine tailings and binders is a relatively new technology, a review of the binding materials used in such formulations and their performance evaluation in mechanical fill behaviour was considered pertinent in

  1. Development of hydroxyapatite bone cement for controlled drug release via tetracycline hydrochloride

    Indian Academy of Sciences (India)

    Sayed Mahmood Rabiee

    2013-02-01

    The purpose of this work was to study the preparation and characterization of drug–hydroxyapatite cement. The hydroxyapatite (HA) cement has been synthesized by using tricalcium phosphate, calcium carbonate and dicalcium phosphate anhydrous with sodium hydrogen phosphate as liquid phase. The effect of added tetracycline hydrochloride (TCH) as drug on final phases, microstructure, setting behaviour and compressive strength has been studied. The drug release rate was first order within the first day and then was zero order. No obvious difference could be detected in XRD patterns of the TCH–HA cement with various amounts of drug. By increasing the drug concentration, mechanical strength of cement was decreased and its setting time was increased. The results of this study demonstrate the potential of using HA cement as a carrier for drug delivery.

  2. Method of synthesis of anhydrous thorium(IV) complexes

    Science.gov (United States)

    Kiplinger, Jaqueline L; Cantat, Thibault

    2013-04-30

    Method of producing anhydrous thorium(IV) tetrahalide complexes, utilizing Th(NO.sub.3).sub.4(H.sub.2O).sub.x, where x is at least 4, as a reagent; method of producing thorium-containing complexes utilizing ThCl.sub.4(DME).sub.2 as a precursor; method of producing purified ThCl.sub.4(ligand).sub.x compounds, where x is from 2 to 9; and novel compounds having the structures: ##STR00001##

  3. SCIENTIFIC AND TECHNICAL PRECONDITIONS FOR EXTRUDED LIGHTWEIGHT CEMENT SYSTEMS

    Directory of Open Access Journals (Sweden)

    Oreshkin Dmitriy Vladimirovich

    2012-10-01

    The paper also presents the results of the research of the microstructure of spilt Portland cement and hollow glass spheres, their mineral and chemical analyses, as well as the properties of masonry mortars. The paper presents a conclusion that their high process-dependent parameters and superior operating performance are attainable through the introduction of effective hollow glass spheres into masonry mortars and the application of the extrusion method. The aforementioned novelties may reduce the water consumption rate, improve the strength, freeze resistance and durability of cement mortars. The preparation of this paper involved the study of nine reference books. This paper is the first one of a series of papers covering the method of extrusion of lightweight cement mortars.

  4. Design of Fit-for-Purpose Cement to Restore Cement-Caprock Seal Integrity

    Science.gov (United States)

    Provost, R.

    2015-12-01

    This project aims to study critical research needs in the area of rock-cement interfaces, with a special focus on crosscutting applications in the Wellbore Integrity Pillar of the SubTER initiative. This study will focus on design and test fit-for-purpose cement formulations. The goals of this project are as follows: 1) perform preliminary study of dispersing nanomaterial admixtures in Ordinary Portland Cement (OPC) mixes, 2) characterize the cement-rock interface, and 3) identify potential high-performance cement additives that can improve sorption behavior, chemical durability, bond strength, and interfacial fracture toughness, as appropriate to specific subsurface operational needs. The work presented here focuses on a study of cement-shale interfaces to better understand failure mechanisms, with particular attention to measuring bond strength at the cement-shale interface. Both experimental testing and computational modeling were conducted to determine the mechanical behavior at the interface representing the interaction of cement and shale of a typical wellbore environment. Cohesive zone elements are used in the finite element method to computationally simulate the interface of the cement and rock materials with varying properties. Understanding the bond strength and mechanical performance of the cement-formation interface is critical to wellbore applications such as sequestration, oil and gas production and exploration and nuclear waste disposal. Improved shear bond strength is an indication of the capability of the interface to ensure zonal isolation and prevent zonal communication, two crucial goals in preserving wellbore integrity. Understanding shear bond strength development and interface mechanics will provide an idea as to how the cement-formation interface can be altered under environmental changes (temperature, pressure, chemical degradation, etc.) so that the previously described objectives can be achieved. Sandia National Laboratories is a multi

  5. Advantages of using glycolic acid as a retardant in a brushite forming cement.

    Science.gov (United States)

    Mariño, Faleh Tamimi; Torres, Jesús; Hamdan, Mohammad; Rodríguez, Carmen Rueda; Cabarcos, Enrique López

    2007-11-01

    In this study we have compared the effect of using acetic, glycolic, and citric acids on the brushite cement setting reaction and the properties of the resultant cement. The cement solid phase was made by mixing beta-tricalcium phosphate (beta-TCP), monocalcium dihydrogen phosphate anhydrate (MCPA), and sodium pyrophosphate, whereas the cement liquid phase consisted of aqueous solutions of carboxy acids at concentrations ranging from 0.5 to 3.5M. Cements were prepared by mixing the solid phase with the liquid phase to form a workable paste. The cement setting time was longer for glycolic and citric acids. The best mechanical properties in dry environments were obtained using glycolic and citric acid liquid phases. In a wet environment at 37 degrees C, the cement set with glycolic acid was the strongest one. Brushite cement diametral tensile strength seems to be affected by the calcium-carboxyl phase produced in the setting reaction. The acceptable setting time and mechanical properties of cements set in glycolic acid solutions are attributed to the additional hydrophilic groups in the carboxylic acid and the low solubility in water of the calcium salt produced in the reaction. Moreover, at high concentrations, carboxylic acids add chemically to the cement matrix becoming reactants themselves.

  6. Factor ten emission reductions : the key to sustainable development and economic prosperity for the cement and concrete industry

    Energy Technology Data Exchange (ETDEWEB)

    Horton, R. [Alchemix Corp., Pittsburgh, PA (United States)

    2001-07-01

    This paper proposes that the negative environmental effects of current cement/concrete production can be reduced by a factor of 10 by using cement blends with minimum portland cement and maximum pozzolanic loading. In addition to extending the longevity of concrete, such cement blends also avoid the huge cost of repairs and replacement cycles. Market forces will drive this transition toward sustainable development in the concrete and cement industry. The economic advantages of improving the quality of the concrete are great. Even if improving the concrete doubles the price of the highest quality cement, this would only add 2 per cent to the cost of the overall construction project, but the service life of the structure would give a many-fold return on this added investment. Also, regulations on carbon dioxide emissions in the near future will assume economic importance in the manufacturing of cement and concrete. While portland cements have dominated the construction industry for more than 150 years, new blended cements priced on a performance basis will become the standard in the twenty first century. Currently, the typical cement formulation in the United States, if it contains fly ash, contains 15 to 20 per cent fly ash by weight of the total cementitious material. This paper states that soon the number will be 50 to 60 per cent ash. Fly ash will be widely acknowledged for improving critical performance characteristics of concrete such as workability, impermeability and durability. Carbon dioxide credits will also be a major economic factor that will drive the cement industry toward a factor ten environmental improvement. The Kyoto Protocol calls for the trading of greenhouse gas credits which includes carbon dioxide credits. Under the new system, cement producers will be taxed on excess emissions, while those using pozzolans in their cements will earn credits to offset these penalties. 10 refs.

  7. Utilization of ground waste seashells in cement mortars for masonry and plastering.

    Science.gov (United States)

    Lertwattanaruk, Pusit; Makul, Natt; Siripattarapravat, Chalothorn

    2012-11-30

    In this research, four types of waste seashells, including short-necked clam, green mussel, oyster, and cockle, were investigated experimentally to develop a cement product for masonry and plastering. The parameters studied included water demand, setting time, compressive strength, drying shrinkage and thermal conductivity of the mortars. These properties were compared with those of a control mortar that was made of a conventional Portland cement. The main parameter of this study was the proportion of ground seashells used as cement replacement (5%, 10%, 15%, or 20% by weight). Incorporation of ground seashells resulted in reduced water demand and extended setting times of the mortars, which are advantages for rendering and plastering in hot climates. All mortars containing ground seashells yielded adequate strength, less shrinkage with drying and lower thermal conductivity compared to the conventional cement. The results indicate that ground seashells can be applied as a cement replacement in mortar mixes and may improve the workability of rendering and plastering mortar.

  8. A rapid cyclic voltammetric method for studying cement factors affecting the corrosion of reinforced concrete

    Energy Technology Data Exchange (ETDEWEB)

    Foulkes, F.R.; McGrath, P. (Univ. of Toronto, Ontario (Canada))

    1999-06-01

    A rapid cyclic voltammetric method for studying the influence of cement factors on the corrosion of embedded iron and steel in hardened cement paste is described. The technique employs a cement electrode'' consisting of an iron or steel wire embedded in a miniature cylinder of hardened cement paste. The rapid cyclic voltammetric method is fast, reproducible, and provides information on the corrosiveness of the pore solution environment surrounding the embedded metal. The usefulness of the method is demonstrated by showing how it can be used to evaluate the threshold chloride content of hardened ordinary portland cement paste at which corrosion begins and by using it to evaluate the relative efficacy of several admixed corrosion inhibitors.

  9. Influence of curing conditions on durability of alkali-resistant glass fibres in cement matrix

    Indian Academy of Sciences (India)

    Arabi Nourredine

    2011-07-01

    Glass fibres in concrete material often increase the flexural strength. However, these fibres when in contact with cement are altered by alkali reactions due to the presence of portlandite. This study presents the results of investigation to show the effect of curing conditions on the durability of alkali-resistant glass fibres in cement matrix. Test results show that even alkali resistant fibres treated with zirconium oxide present the same degradation phenomenon. They also show that the nature of the cement has a large influence on the protection of the fibres: the Portland CEM II is less damaging than the CEM I. The substitutions of a part of cement by silica fume gave no substantial improvements to the mechanical strength of the glass fibre reinforced cement (GFRC). However, the observed microstructures in the samples show that the degradation is weakened with the addition of silica fumes. The analytical techniques used in this study are scanning electron microscope (SEM) and X-ray diffraction.

  10. Strength Development and Microstructure of Hardened Cement Paste Blended with Red Mud

    Institute of Scientific and Technical Information of China (English)

    PAN Zhihua; ZHANG Yanna; XU Zhongzi

    2009-01-01

    Red mud was activated to be a mineral admixture for Portland cement by means of heating at different elevated temperatures from 400 ℃ to 700 ℃. Results show that heating was ef-fective, among which thermal activation of red mud at 600 ℃ was most effective. Chemical analysis suggested that cement added with 600 ℃ thermally activated red mud yielded more calcium ion dur-ing the early stage of hydration and less at later stage in liquid phase of cement water suspension sys-tem, more combined water and less calcium hydroxide in its hardened cement paste. MIP measure-ment and SEM observation proved that the hardened cement paste had a similar total porosity and a less portion of large size pores hence a denser microstructure compared with that added with original red mud.

  11. Influence of zeolite and cement additions on mechanical behavior of sandy soil

    Institute of Scientific and Technical Information of China (English)

    Hossein Mola-Abasi; Issa Shooshpasha

    2016-01-01

    It is well known that the cemented sand is one of economic and environmental topics in soil stabili-zation. In this instance, a blend of sand, cement and other materials such as fiber, glass, nanoparticle and zeolite can be commercially available and effectively used in soil stabilization in road construction. However, the influence and effectiveness of zeolite on the properties of cemented sand systems have not been completely explored. In this study, based on an experimental program, the effects of zeolite on the characteristics of cemented sands are investigated. Stabilizing agent includes Portland cement of type II and zeolite. Results show the improvements of unconfined compressive strength (UCS) and failure properties of cemented sand when the cement is replaced by zeolite at an optimum proportion of 30%after 28 days. The rate of strength improvement is approximately between 20%and 78%. The efficiency of using zeolite increases with the increases in cement amount and porosity. Finally, a power function of void-cement ratio and zeolite content is demonstrated to be an appropriate method to assess UCS of zeolite-cemented mixtures.

  12. Influence of zeolite and cement additions on mechanical behavior of sandy soil

    Directory of Open Access Journals (Sweden)

    Hossein Mola-Abasi

    2016-10-01

    Full Text Available It is well known that the cemented sand is one of economic and environmental topics in soil stabilization. In this instance, a blend of sand, cement and other materials such as fiber, glass, nanoparticle and zeolite can be commercially available and effectively used in soil stabilization in road construction. However, the influence and effectiveness of zeolite on the properties of cemented sand systems have not been completely explored. In this study, based on an experimental program, the effects of zeolite on the characteristics of cemented sands are investigated. Stabilizing agent includes Portland cement of type II and zeolite. Results show the improvements of unconfined compressive strength (UCS and failure properties of cemented sand when the cement is replaced by zeolite at an optimum proportion of 30% after 28 days. The rate of strength improvement is approximately between 20% and 78%. The efficiency of using zeolite increases with the increases in cement amount and porosity. Finally, a power function of void-cement ratio and zeolite content is demonstrated to be an appropriate method to assess UCS of zeolite-cemented mixtures.

  13. Development of monetite/phosphorylated chitosan composite bone cement.

    Science.gov (United States)

    Boroujeni, Nariman Mansouri; Zhou, Huan; Luchini, Timothy J F; Bhaduri, Sarit B

    2014-02-01

    In this article, we report the development of a biodegradable monetite [dicalcium phosphate anhydrous (DCPA), CaHPO4 ]/phosphorylated chitosan (p-chitosan) composite orthopedic cement. The cement pastes showed desirable handling properties, injectability, and washout resistance. The incorporation of p-chitosan powders at 5 wt % shortened the setting time of DCPA and significantly improved the mechanical performance of DCPA cement, increasing the compressive strength almost twice from 11.09 ± 1.85 MPa at 0% chitosan to 23.43 ± 1.47 MPa at 5 wt % p-chitosan. On the other hand, higher p-chitosan content or untreated chitosan incorporation lowered the performance of DCPA cements. The cytocompatibility of the composite cement was investigated in vitro using the preosteoblast cell line MC3T3-E1. An increase in cell proliferation was observed in both DCPA and DCPA-p-chitosan. The results show that both the materials are as cytocompatible as hydroxyapatite. Based on these results, DCPA-p-chitosan composite cement can be considered as potential bone repair material.

  14. Wellbore cement fracture evolution at the cement–basalt caprock interface during geologic carbon sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hun Bok; Kabilan, Senthil; Carson, James P.; Kuprat, Andrew P.; Um, Wooyong; Martin, Paul F.; Dahl, Michael E.; Kafentzis, Tyler A.; Varga, Tamas; Stephens, Sean A.; Arey, Bruce W.; Carroll, KC; Bonneville, Alain; Fernandez, Carlos A.

    2014-08-07

    Composite Portland cement-basalt caprock cores with fractures, as well as neat Portland cement columns, were prepared to understand the geochemical and geomechanical effects on the integrity of wellbores with defects during geologic carbon sequestration. The samples were reacted with CO2-saturated groundwater at 50 ºC and 10 MPa for 3 months under static conditions, while one cement-basalt core was subjected to mechanical stress at 2.7 MPa before the CO2 reaction. Micro-XRD and SEM-EDS data collected along the cement-basalt interface after 3-month reaction with CO2-saturated groundwater indicate that carbonation of cement matrix was extensive with the precipitation of calcite, aragonite, and vaterite, whereas the alteration of basalt caprock was minor. X-ray microtomography (XMT) provided three-dimensional (3-D) visualization of the opening and interconnection of cement fractures due to mechanical stress. Computational fluid dynamics (CFD) modeling further revealed that this stress led to the increase in fluid flow and hence permeability. After the CO2-reaction, XMT images displayed that calcium carbonate precipitation occurred extensively within the fractures in the cement matrix, but only partially along the fracture located at the cement-basalt interface. The 3-D visualization and CFD modeling also showed that the precipitation of calcium carbonate within the cement fractures after the CO2-reaction resulted in the disconnection of cement fractures and permeability decrease. The permeability calculated based on CFD modeling was in agreement with the experimentally determined permeability. This study demonstrates that XMT imaging coupled with CFD modeling represent a powerful tool to visualize and quantify fracture evolution and permeability change in geologic materials and to predict their behavior during geologic carbon sequestration or hydraulic fracturing for shale gas production and enhanced geothermal systems.

  15. ULTRA-LIGHTWEIGHT CEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fred Sabins

    2002-07-30

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). This report includes results from laboratory testing of ULHS systems along with other lightweight cement systems, including foamed and sodium silicate slurries. During this project quarter, a comparison study of the three cement systems examined the effect that cement drillout has on the three cement systems. Testing to determine the effect of pressure cycling on the shear bond properties of the cement systems was also conducted. This report discusses testing that was performed to analyze the alkali-silica reactivity of ULHS in cement slurries.

  16. Sodium Sulphate Effect on Cement Produced with Building Stone Waste

    Directory of Open Access Journals (Sweden)

    Emre Sancak

    2015-01-01

    Full Text Available In this study, the blended cements produced by using the building stone waste were exposed to sulphate solution and the cement properties were examined. Prepared mortar specimens were cured under water for 28 days and then they were exposed to three different proportions of sodium sulphate solution for 125 days. Performances of cements were determined by means of compressive strength and tensile strength tests. The broken parts of some mortar bars were examined with scanning electron microscope (SEM. Besides, they were left under moist atmosphere and their length change was measured and continuously monitored for period of 125 days. In blended cements, solely cements obtained by replacing 10–20% of diatomites gave similar strength values with ordinary Portland cement (CEM I 42.5R at the ages of 7, 28, and 56 days. In all mortar specimens that included either waste andesite (AP or marble powder (MP showed best performance against very severe effective sodium sulphate solutions (13500 mg/L.

  17. Effect of supplementary cementing materials on the concrete corrosion control

    Directory of Open Access Journals (Sweden)

    Mejía de Gutiérrez, R.

    2003-12-01

    Full Text Available Failure of concrete after a period of years, less than the life expected for which it was designed, may be caused by the environment to which it has been exposed or by a variety of internal causes. The incorporation of supplementary materials has at the Portland cement the purpose of improving the concrete microstructure and also of influence the resistance of concrete to environmental attacks. Different mineral by-products as ground granulated blast furnace slag (GGBS, silica fume (SF, metakaolin (MK, fly ash (FA and other products have been used as supplementary cementing materials. This paper is about the behavior of concrete in the presence of mineral additions. Compared to Portland cements, blended cements show lower heat of hydration, lower permeability, greater resistance to sulphates and sea water. These blended cements find the best application when requirements of durability are regarded as a priority specially on high performance concrete.

    La falla del concreto en un tiempo inferior a la vida útil para la cual se diseñó puede ser consecuencia del medio ambiente al cual ha estado expuesto o de algunas otras causas de tipo interno. La incorporación de materiales suplementarios al cemento Portland tiene el propósito de mejorar la microestructura del concreto y también de contribuir a la resistencia del concreto a los ataques del medio ambiente. Diferentes minerales y subproductos tales como escorias granuladas de alto horno, humo de sílice, metacaolín, ceniza volante y otros productos han sido usados como materiales suplementarios cementantes. Este documento presenta el comportamiento del hormigón en presencia de diferentes adiciones. Los cementos adicionados, comparados con los cementos Portland muestran bajos calores de hidratación, baja permeabilidad, mayor resistencia a sulfatos y a agua de mar. Estos cementos adicionados encuentran un campo de aplicación importante cuando los requerimientos de durabilidad son

  18. Interaction between cements with different composition and superplasticizers

    Directory of Open Access Journals (Sweden)

    Ghorab, H. Y.

    2012-09-01

    Full Text Available The slump behavior of ordinary Portland-, pozzolanic (red brick powder-, sulfate resistant-, and limestone cement pastes caused by ≤ 1% additions of polycondensates and polycarboxylates superplasticizers are monitored for up to 90 minutes. With the plolycondensates, Portland- and pozzolanic cements gain fluidity at higher dosages than sulfate resistant and limestone cements. Limestone cement shows the best slump retention. The aluminate and sulfate phases play a major role in the fluidity. With the polycarboxylates, all cements gain fluidity with dosages of ≤ 0.3%. A polycarboxylate with no resonance of methyl methylene proton in the main chain identified in the NMR spectra creates good slump retention. This is explained by a low mobility of the structure and the predominance of the steric effect. The polycarboxylate shows also strong ether bands relative to the ester groups in the IR spectra and a low polydispersity observed in the elution of few low molecular weight species in the HPLC chromatogram.Se ha estudiado el efecto fluidificante (hasta 90 minutos ejercido por la incorporación de entre 0-1% de aditivos policondensados y policarboxilatos en pastas de cemento Portland, puzolánico, resistente a sulfatos y con adición de caliza. Con la incorporación de los aditivos policondensados, se produjo un incremento de la fluidez de los cementos Portland y puzolánico a mayores dosificaciones que las necesarias en los cementos resistente a sulfatos y con adición de caliza. Éste último presentó la mejor retención de la fluidez. Las fases aluminatos y sulfatos juegan un importante papel en la fluidez inducida. Todos los cementos incrementaron su fluidez con la incorporación de aditivos policarboxilatos a dosificaciones menores del 0,3%. El policarboxilato que no presenta en los espectros de RMN, resonancia asignada al protón de los grupos metil metileno, presenta buena retención de la fluidez. Esto es debido a la baja flexibilidad de

  19. Cement-based materials' characterization using ultrasonic attenuation

    Science.gov (United States)

    Punurai, Wonsiri

    The quantitative nondestructive evaluation (NDE) of cement-based materials is a critical area of research that is leading to advances in the health monitoring and condition assessment of the civil infrastructure. Ultrasonic NDE has been implemented with varying levels of success to characterize cement-based materials with complex microstructure and damage. A major issue with the application of ultrasonic techniques to characterize cement-based materials is their inherent inhomogeneity at multiple length scales. Ultrasonic waves propagating in these materials exhibit a high degree of attenuation losses, making quantitative interpretations difficult. Physically, these attenuation losses are a combination of internal friction in a viscoelastic material (ultrasonic absorption), and the scattering losses due to the material heterogeneity. The objective of this research is to use ultrasonic attenuation to characterize the microstructure of heterogeneous cement-based materials. The study considers a real, but simplified cement-based material, cement paste---a common bonding matrix of all cement-based composites. Cement paste consists of Portland cement and water but does not include aggregates. First, this research presents the findings of a theoretical study that uses a set of existing acoustics models to quantify the scattered ultrasonic wavefield from a known distribution of entrained air voids. These attenuation results are then coupled with experimental measurements to develop an inversion procedure that directly predicts the size and volume fraction of entrained air voids in a cement paste specimen. Optical studies verify the accuracy of the proposed inversion scheme. These results demonstrate the effectiveness of using attenuation to measure the average size, volume fraction of entrained air voids and the existence of additional larger entrapped air voids in hardened cement paste. Finally, coherent and diffuse ultrasonic waves are used to develop a direct

  20. The Properties of Cement Mortars Modified by Emulsified Epoxy and Micro-fine Slag

    Institute of Scientific and Technical Information of China (English)

    CHEN You-zhi; WANG Hong-xi; MA Zhi-yong; LI Qing-hua

    2003-01-01

    The epoxy resin polymer cement mortars with excellent performances were made up through modifying ordinary Portland cement with emulsified epoxy and micro-fine slag.The microstructure of the epoxy resin polymer cement materials was studied and their hydration and hardening characteristics were discussed by means of modern analysis measures such as SEM,XRD and Hg-intrusion micromeritics.The experimental results indicate that the series effects of water-reducing,density,pozzolanicity,filling and solidification crosslinking through the action together with epoxy organism and micro-fine slag endowed cement-based materials with perfect performances.The main hydration products in the system are C-S-H gel and hydrated calcium aluminate.At later age,AFt can be in existence,and no Ca(OH)2 is found.When epoxy resin is solidified,the organism is in a network structure.In the micro-pore structure of hydrated cement with modified epoxy and fine slag,big harmful pores were fewer,more harmless abundant micro pores were and the possible pore radius was smaller than that of ordinary Portland cement.