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Sample records for anhydrous portland cements

  1. 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...

  2. Use of X-ray diffraction to quantify amorphous supplementary cementitious materials in anhydrous and hydrated blended cements

    International Nuclear Information System (INIS)

    The content of individual amorphous supplementary cementitious materials (SCMs) in anhydrous and hydrated blended cements was quantified by the PONKCS [1] X-ray diffraction (XRD) method. The analytical precision and accuracy of the method were assessed through comparison to a series of mixes of known phase composition and of increasing complexity. A 2σ precision smaller than 2–3 wt.% and an accuracy better than 2 wt.% were achieved for SCMs in mixes with quartz, anhydrous Portland cement, and hydrated Portland cement. The extent of reaction of SCMs in hydrating binders measured by XRD was 1) internally consistent as confirmed through the standard addition method and 2) showed a linear correlation to the cumulative heat release as measured independently by isothermal conduction calorimetry. The advantages, limitations and applicability of the method are discussed with reference to existing methods that measure the degree of reaction of SCMs in blended cements

  3. MTA versus Portland cement: review of literature

    OpenAIRE

    Naiana Viana Viola; Mário Tanomaru Filho; Paulo Sérgio Cerri

    2011-01-01

    Introduction: Both Mineral Trioxide Aggregate (MTA) and Portland cement (PC) have been highlighted because of their favorable biological properties, with extensive applications in Endodontics, including the possibility of using into root canal filling. Objective: This article reviews literature related to MTA and PC comparing their physical, chemical and biological properties, as well as their indications. Literature review: Literature reports studies revealing the similarities between these ...

  4. MTA versus Portland cement: review of literature

    Directory of Open Access Journals (Sweden)

    Naiana Viana Viola

    2011-10-01

    Full Text Available Introduction: Both Mineral Trioxide Aggregate (MTA and Portland cement (PC have been highlighted because of their favorable biological properties, with extensive applications in Endodontics, including the possibility of using into root canal filling. Objective: This article reviews literature related to MTA and PC comparing their physical, chemical and biological properties, as well as their indications. Literature review: Literature reports studies revealing the similarities between these materials’ properties, including both biocompatibility and bone repair induction. Moreover, there is the need for the development of a root canal sealer based on these materials (MTA and PC. Conclusion: MTA and CP show promissory perspective both in Dentistry and Endodontics.

  5. 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

  6. In situ hydration of Portland cement monitored by neutron diffraction

    Science.gov (United States)

    Castellote, M.; Alonso, C.; Andrade, C.; Campo, J.; Turrillas, X.

    Ordinary Portland cement was mixed with deuterium oxide with a heavy water/cement ratio of 0.6 to monitor the in situ hydration, while acquiring diffraction patterns every 2.5min. Two different experiments were carried out under different heating conditions. In one case, the temperature was uniformly raised from room temperature to 98 °C at a heating rate of 20 °C/h. In the second case, the heating was performed from 32 °C to 100 °C at a slower rate: 12 °C/h. The disappearance and appearance of relevant anhydrous and hydrated phases were monitored and quantified by fitting isolated diffraction peaks to Gaussians. Ca3SiO5 dissolved completely during the experiment and Ca2SiO4 only partially disappeared. Ca(OD)2 precipitated and its growth rate exhibited a sigmoidal shape. Ettringite and hillebrandite formed but then dissolved before the end of the experiments. At the end only Ca(OD)2 and some Ca2SiO4 remained as crystalline phases.

  7. The comparison between sulfate salt weathering of portland cement paste and calcium sulfoaluminate cement paste

    OpenAIRE

    Liu, Zanqun; Deng, Dehua; De Schutter, Geert

    2015-01-01

    In this paper, the damage performances of sulfate salt weathering of Portland cement paste and calcium sulfoaluminate (CSA) cement paste were compared according to authors' previous studies. It was found that the evaporation zone of speciments partially immersed in 10% Na2SO4 solution were both severely deteriorated for Portland cement and CSA cement. However, the differences were more significant: (1) the CSA cement paste were damaged just after 7 days exposure compared to the 5 months expos...

  8. New method for analysis of portland cements with secondary components

    Directory of Open Access Journals (Sweden)

    Gomá, F.

    1986-03-01

    Full Text Available We describe a new method for the determination of the composition of Portland cement mixtures with active additions and the identification of the type of addition. This method enables us to classify a Portland cement or Portland with active additions, whatever this addition may be, and it is specially suitable for discriminating the type of slag when there are slags present.

    Se describe un nuevo método para determinar la composición de las mezclas de cemento Portland con adiciones activas e identificar el tipo de adición. Permite la clasificación de un cemento Portland o Portland con adiciones activas cualquiera que sea la adición y es especialmente indicado para discriminar el tipo de escoria cuando están presentes.

  9. Preterm delivery among people living around Portland cement plants.

    Science.gov (United States)

    Yang, Chun-Yuh; Chang, Chih-Ching; Tsai, Shang-Shyue; Chuang, Hung-Yi; Ho, Chi-Kung; Wu, Trong-Neng; Sung, Fung-Chang

    2003-05-01

    The Portland cement industry is the main source of particulate air pollution in Kaohsiung city. Data in this study concern outdoor air pollution and the health of individuals living in communities in close proximity to Portland cement plants. The prevalence of delivery of preterm birth infants was significantly higher in mothers living within 0-2 km of a Portland cement plant than in mothers living within 2-4 km. After controlling for several possible confounders (including maternal age, season, marital status, maternal education, and infant sex), the adjusted odds ratio was 1.30 (95% CI=1.09-1.54) for the delivery of preterm infants for mothers living close to the Portland cement plants, chosen at the start to be from 0 to 2 km. These data provide further support for the hypothesis that air pollution can affect the outcome of pregnancy. PMID:12706757

  10. Preterm delivery among people living around Portland cement plants

    International Nuclear Information System (INIS)

    The Portland cement industry is the main source of particulate air pollution in Kaohsiung city. Data in this study concern outdoor air pollution and the health of individuals living in communities in close proximity to Portland cement plants. The prevalence of delivery of preterm birth infants as significantly higher in mothers living within 0-2 km of a Portland cement plant than in mothers living within 2-4 km. After controlling for several possible confounders (including maternal age, season, marital status, maternal education, and infant sex), the adjusted odds ratio was 1.30 (95% I=1.09-1.54) for the delivery of preterm infants for mothers living close to he Portland cement plants, chosen at the start to be from 0 to 2 km. These data provide further support for the hypothesis that air pollution can affect he outcome of pregnancy

  11. Portland cement conditioning of the oil radioactive wastes

    International Nuclear Information System (INIS)

    Cementation is a widely used method to immobilize radioactive wastes generated during the operation of nuclear power plants. The oily radioactive wastes resulting during the normal service of Nuclear Power Plant at Cernavoda, Romania, can be conditioned in Portland cement as emulsions. In this way the interaction with cement water is not blocked. For this purpose, four compositions for conditioning were studied, namely: i) cement-emulsion; ii) cement-emulsion-sodium silicate; iii) cement-emulsion-sodium silicate-lime; iv) cement-emulsion-sand. The apparent density of hardened binding mixtures, setting time, compressive strength of hardened samples, leaching rate of tritium were determined. The results have shown that the oily wastes can be conditioned in a good manner when using Portland cement, emulsion conditioners, sodium silicate and lime. (authors)

  12. Injectable citrate-modified Portland cement for use in vertebroplasty

    OpenAIRE

    Wynn-Jones, Gareth; Shelton, Richard M.; Hofmann, Michael P

    2014-01-01

    The injectability of Portland cement (PC) with several citrate additives was investigated for use in clinical applications such as vertebroplasty (stabilization of a fractured vertebra with bone cement) using a syringe. A 2-wt % addition of sodium or potassium citrate with PC significantly improved cement injectability, decreased cement setting times from over 2 h to below 25 min, while increasing the compressive strength to a maximum of 125 MPa. Zeta-potential measurements indicated that the...

  13. THE INFLUENCE OF ORTHOPHOSPHATES ON THE PROPERTIES OF PORTLAND CEMENT

    OpenAIRE

    Antanas Kaziliunas

    2014-01-01

    The article continues the research of input reduction of phosphogypsum preparation for the production of building materials. Desiccated apatite (2.18 % P2O5 in gypsum) makes the least changes in the properties of Portland cement: it prolongs the cement setting times and reduces the compressive strength about 10 %. The apatite formation in the pastes of soluble orthophosphate-cement occurs during the formation of X-ray amorphous colloidal calcium orthophosphate hydrate, which prolo...

  14. 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.

  15. 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.

  16. 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. PMID:25842101

  17. Symptoms, ventilatory function, and environmental exposures in Portland cement workers.

    OpenAIRE

    Abrons, H L; Petersen, M R; Sanderson, W T; Engelberg, A L; Harber, P

    1988-01-01

    Data on respiratory symptoms and pulmonary function were obtained for 2736 Portland cement plant workers and 755 controls. Personal dust samples contained a geometric mean concentration of 0.57 mg/m3 for respirable dust and 2.90 mg/m3 for total dust. Cement workers and controls had similar prevalences of symptoms, except that 5.4% of the cement workers had dyspnoea compared with 2.7% of the controls. The mean pulmonary function indices were similar for the two groups. Among cement plant worke...

  18. Utilization of gold tailings as an additive in Portland cement.

    Science.gov (United States)

    Celik, Ozlem; Elbeyli, Iffet Yakar; Piskin, Sabriye

    2006-06-01

    Mine tailings are formed as an industrial waste during coal and ore mining and processing. In the investigated process, following the extraction of gold from the ore, the remaining tailings are subjected to a two-stage chemical treatment in order to destroy the free cyanide and to stabilize and coagulate heavy metals prior to discharge into the tailings pond. The aim of this study was the investigation of the feasibility of utilization of the tailings as an additive material in Portland cement production. For this purpose, the effects of the tailings on the compressive strength properties of the ordinary Portland cement were investigated. Chemical and physical properties, mineralogical composition, particle size distribution and microstructure of the tailings were determined by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), particle size analyzer (Mastersizer) and scanning electron microscope (SEM). Following the characterization of the tailings, cement mortars were prepared by intergrinding Portland cement with dried tailings. Composition of the cement clinkers were adjusted to contain 5, 15, 25% (wt/wt) dried tailings and also silica fume and fly ash samples (C and F type) were added to clinker in different ratios. The mortars produced with different amounts of tailings, silica fume, fly ashes and also mixtures of them were tested for compressive strength values after 2, 7, 28 and 56 days according to the European Standard (EN 196-1). The results indicated that gold tailings up to 25% in clinker could be beneficially used as an additive in Portland cement production. It is suggested that the gold tailings used in the cement are blended with silica fume and C-type fly ash to obtain higher compressive strength values. PMID:16784164

  19. Low porosity portland cement pastes based on furan polymers

    International Nuclear Information System (INIS)

    The effect of three different types of Furan polymers on the porosity, mechanical properties, mechanism of hydration and microstructure of Ordinary Portland cement (OPC) pastes was investigated. The results showed that mixing the OPC with Furan polymers, the standard water of consistency of the different cement pastes decreases and therefore the setting times (initial and final) are shortened. The total porosity of the hardened cement pastes decreased, while the mechanical properties improved and enhanced at all curing ages of hydration compared with those of the pure OPC pastes. The hydration process with Furan polymers proceeded according to the following decreasing order: F.ac. > F.ph. > F.alc. > OPC

  20. Pre-portland cements and geopolymers

    Czech Academy of Sciences Publication Activity Database

    Hanzlíček, Tomáš; Perná, Ivana; Ertl, Z.; Miller, S.M.

    2012-01-01

    Roč. 9, č. 1 (2012), s. 57-62. ISSN 1214-9705 Institutional research plan: CEZ:AV0Z30460519 Keywords : caementum * cement itious * calcareous cement Subject RIV: JN - Civil Engineering Impact factor: 0.530, year: 2011 http://www.irsm.cas.cz/materialy/acta_content/2012_01/5_Hanzlicek.pdf

  1. Use of red mud as addition for portland cement mortars

    International Nuclear Information System (INIS)

    The aim of the present research work was to investigate the possibility of adding red mud, an alkaline leaching waste that is obtained from bauxite during the Bayer process for alumina production, in the raw meal of Portland cement mortars. The red mud is classified as dangerous, according to NBR 10004/2004, and world while generation reached over 117 million tons/year. This huge production requires high consuming products to be used as incorporation matrix and we studied the influence of red mud addition on the characteristics of cement mortars and concrete. In this paper the properties of Portland cement mortars incorporating high amounts of red mud was evaluated: pH variation, fresh (setting time, workability or normal consistency and water retention), and hardened state (mechanical strength, capillary water absorption, density and apparent porosity). Results seem promising for red mud additions up to 20 wt%. (author)

  2. Microstructure Analysis of Heated Portland Cement Paste

    OpenAIRE

    Q. Zhang; 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 of cement paste. In order to study the microstructure changes at high temperature, in this contribution the cement paste samples were firstly heated to varied temperatures from 100 °C to 1000 °C wit...

  3. Injectable citrate-modified Portland cement for use in vertebroplasty.

    Science.gov (United States)

    Wynn-Jones, Gareth; Shelton, Richard M; Hofmann, Michael P

    2014-11-01

    The injectability of Portland cement (PC) with several citrate additives was investigated for use in clinical applications such as vertebroplasty (stabilization of a fractured vertebra with bone cement) using a syringe. A 2-wt % addition of sodium or potassium citrate with PC significantly improved cement injectability, decreased cement setting times from over 2 h to below 25 min, while increasing the compressive strength to a maximum of 125 MPa. Zeta-potential measurements indicated that the citrate anion was binding to one or more of the positively charged species causing charged repulsion between cement particles which dispersed aggregates and caused the liquefying effect of the anion. Analysis of the hydrating phases of PC indicated that the early strength producing PC phase (ettringite) developed within the first 2 h of setting following addition of the citrate anion, while this did not occur in the control cement (PC only). Within 24 h ettringite developed in PC as well as calcium-silicate-hydrate (C-S-H), the major setting phase of PC, whereas cements containing citrate did not develop this phase. The evidence suggested that in the presence of citrate the cements limited water supply appeared to be utilized for ettringite formation, producing the early strength of the citrate cements. The present study has demonstrated that it is possible to modify PC with citrate to both improve the injectability and crucially reduce the setting times of PC while improving the strength of the cement. PMID:24711245

  4. 76 FR 76760 - Gray Portland Cement and Cement Clinker From Japan

    Science.gov (United States)

    2011-12-08

    ... review. Background The Commission instituted this review on May 2, 2011 (76 FR 24519) and determined on August 5, 2011 that it would conduct an expedited review (76 FR 50252, August 12, 2011). The Commission... COMMISSION Gray Portland Cement and Cement Clinker From Japan Determination On the basis of the record...

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

    OpenAIRE

    Pangdaeng, S.; Sata, V.; Aguiar, J. L. Barroso de; Torgal, Fernando Pacheco; Chindaprasirt, P.

    2015-01-01

    In this study, calcined kaolin–white Portland cement geopolymerwas investigated for use as biomaterial. Sodiumhydroxide 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 co...

  6. 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.

  7. Scrap tire ashes in portland cement production

    OpenAIRE

    Mónica Adriana Trezza; Alberto Néstor Scian

    2009-01-01

    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 th...

  8. 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.

  9. Estimated longevity of performance of Portland cement grout seal materials

    International Nuclear Information System (INIS)

    The sealing of boreholes, fractures and underground workings of repositories is a common concern for all programs investigating the deep burial of nuclear waste as a disposal mechanism. Two grouting materials, bentonite and portland cement, have been identified by many programs as likely candidate seal materials. The longevity of performance of both of these materials is currently being investigated under the auspices of the Stripa Project. These investigations comprise coordinated laboratory, field and modeling studies to produce fundamental data, practical experience and estimates of long-range performance, respectively. Long-term performance is an especially sensitive issue for cement because the phases that comprise cement are metastable. Accordingly, it may be assumed that cement grout performance will degrade with time. For a simplified cement system, two mechanisms for chemical degradation have been considered: phase change and dissolution. When considering dissolution, both equilibrium (slow flow) and open (fast flow) systems have been analyzed to establish bounds. Granitic terrain groundwaters ranging from fresh to saline have been taken as solvents. To assess the consequences in terms of flow, an empirical relation between cement permeability and porosity has been developed. Predictions of performance changes with time have been produced by making conservative estimates of local hydraulic head conditions for various periods of repository history. For the crystalline rock environments considered, preliminary results indicate that cement grout performance may be acceptable for tens of thousands to millions of years providing its initial hydraulic conductivity is on the order of 10-12 m/s

  10. 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

    Solid-state, magic-angle spinning (MAS) NMR spectroscopy represents a valuable tool for structural investigations on the nanoscale of the most important phases in anhydrous and hydrated Portland cements and of various admixtures. This is primarily due to the fact that the method reflects the first...... have been investigated in detail by 29Si and 27Al MAS NMR where the combination of the results for these spin-nuclei provides important information on the degree of Al-incorporation in the C-S-H structure and of the average chain lengths of tetrahedral SiO4 and AlO4 units. This presentation will...

  11. 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.

  12. Hydration of Portland cement with additions of calcium sulfoaluminates

    International Nuclear Information System (INIS)

    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.

  13. Early hydration of portland cement with crystalline mineral additions

    International Nuclear Information System (INIS)

    This research presents the effects of finely divided crystalline mineral additions (quartz and limestone), commonly known as filler, on the early hydration of portland cements with very different mineralogical composition. The used techniques to study the early hydration of blended cements were conduction calorimeter, hydraulicity (Fratini's test), non-evaporable water and X-ray diffraction. Results showed that the stimulation and the dilution effects increase when the percentage of crystalline mineral additions used is increased. Depending on the replacement proportion, the mineralogical cement composition and the type of crystalline addition, at 2 days, the prevalence of the dilution effect or the stimulation effect shows that crystalline mineral additions could act as sites of heat dissipation or heat stimulation, respectively

  14. Synthesis report: D-cracking in portland cement concrete pavements

    Science.gov (United States)

    Thompson, S. R.; Olsen, M. P. J.; Dempsey, B. J.

    1980-06-01

    The mechanisms and testing procedures for D-cracking in portland cement concrete pavements are examined. Benefication procedures are also investigated. The three general responses to freezing in the aggregate/paste system include elastic accommodation, high internal pressure, and high external pressure. It is found that the critical aggregate parameters influencing D-cracking are degree of saturation, maximum particle size, permeability, porosity, and pore size distribution. Evaluation of present laboratory testing procedures indicated that the ASTM C666, VPI slow-cool, Mercury Porosimetry, and Iowa Pore Index Tests correlated the best with field performance of concrete with respect to D-cracking.

  15. 75 FR 54969 - National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing...

    Science.gov (United States)

    2010-09-09

    ..., 1998; see also 63 FR at 14193 (March 24, 1998) (area source cement kilns' emissions of mercury, dibenzo... NESHAP on May 6, 2009. See 74 FR 21136. We received a total of 3,229 comments from the Portland cement... v. EPA Litigation On June 14, 1999 (64 FR 31898), EPA issued the NESHAP for the Portland...

  16. Superplasticized Portland cement: Production and compressive strength of mortars and concrete

    Energy Technology Data Exchange (ETDEWEB)

    Bouzoubaa, N.; Zhang, M.H.; Malhotra, V.M. [Natural Resources Canada, Ottawa, Ontario (Canada)

    1998-12-01

    This paper deals with the effect of intergrinding different percentages of a naphthalene-based superplasticizer with Portland cement clinker and gypsum on the fineness of the product, and on the water requirement and the compressive strength of the mortars made with the superplasticized cement. The properties of the fresh and hardened concrete made with the superplasticized cements were also investigated. The results showed that the intergrinding of a given amount of a naphthalene-based superplasticizer with Portland clinker and gypsum reduced the grinding time required for obtaining the same Blaine fineness as that of the control Portland cement without the superplasticizer. The water requirement of the mortars made with the superplasticized cements was similar to that of the mortars made with the control Portland cements when the same amount of the superplasticizer was added at the mortar mixer; for a given grinding time and a Blaine fineness of {approximately}4500 cm{sup 2}/g, the mortars made with the superplasticized cement had higher compressive strength than those made with the control Portland cement. For a given grinding time or Blaine fineness of cement {ge}5000 cm{sup 2}/g, the slump loss, air content stability, bleeding, autogenous temperature rise, setting times, and compressive strength of the concrete made with the superplasticized cements were generally comparable to those of the concrete made with the control Portland cements when the superplasticizer was added at the concrete mixer.

  17. Differentiating seawater and groundwater sulfate attack in Portland cement mortars

    International Nuclear Information System (INIS)

    The study reported in this article deals with understanding the physical, chemical and microstructural differences in sulfate attack from seawater and groundwater. Portland cement mortars were completely immersed in solutions of seawater and groundwater. Physical properties such as length, mass, and compressive strength were monitored periodically. Thermal analysis was used to study the relative amounts of phases such as ettringite, gypsum, and calcium hydroxide, and microstructural studies were conducted by scanning electron microscopy. Portland cement mortars performed better in seawater solution compared to groundwater solution. The difference in performance could be attributed to the reduction in the quantity of the expansive attack products (gypsum and ettringite). The high Cl concentration of seawater could have played an important role by binding the C3A to form chloroaluminate compounds, such as Friedel's salt (detected in the microstructural studies), and also by lowering the expansive potential of ettringite. Furthermore, the thicker layer of brucite forming on the specimens in seawater could have afforded better protection against ingress of the solution than in groundwater

  18. 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

  19. Physical evaluation of a new pulp capping material developed from portland cement

    Science.gov (United States)

    Negm, Ahmed; Hassanien, Ehab; Abu-Seida, Ashraf

    2016-01-01

    Background This study examined the effects of addition of 10% and 25% by weight calcium hydroxide on the physicochemical properties of Portland cement associated with 20% bismuth oxide in order to develop a new pulp capping material. Material and Methods The solubility, pH value, setting time, compressive strength, and push out bond strength of modified Portland were evaluated and compared to those of mineral trioxide aggregate (MTA) and Portland cement containing 20% bismuth oxide. Results The statistical analysis was performed with ANOVA and Duncan’s post-hoc test. The results show that the strength properties and push out bond strength of Portland cement were adversely affected by addition of calcium hydroxide especially with a ratio of 25 wt%, however, the setting time and pH were not affected. MTA showed a statistically significant lower setting time than other cements (P≤0.001). Portland cement with bismuth oxide and Port Cal I showed a statistically significant higher Push out Bond strength than MTA and Port Cal II (P=0.001). Conclusions Taking the setting time, push out bond strength and pH value into account, addition of 10 wt% calcium hydroxide to Portland cement associated with 20% bismuth oxide produces a new pulp capping material with acceptable physical and adhesive properties. Further studies are recommended to test this cement biologically as a new pulp capping material. Key words:Calcium hydroxide, MTA, Portland cement, setting time, solubility, strength. PMID:27398178

  20. Utilization of Iron Ore Tailings as Raw Material for Portland Cement Clinker Production

    OpenAIRE

    Li Luo; Yimin Zhang; Shenxu Bao; Tiejun Chen

    2016-01-01

    The cement industry has for some time been seeking alternative raw material for the Portland cement clinker production. The aim of this research was to investigate the possibility of utilizing iron ore tailings (IOT) to replace clay as alumina-silicate raw material for the production of Portland cement clinker. For this purpose, two kinds of clinkers were prepared: one was prepared by IOT; the other was prepared by clay as a reference. The reactivity and burnability of raw meal, mineralogical...

  1. Optimization of calcium chloride content on bioactivity and mechanical properties of white Portland cement

    International Nuclear Information System (INIS)

    This research investigates the optimization of calcium chloride content on the bioactivity and mechanical properties of white Portland cement. Calcium chloride was used as an addition of White Portland cement at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10% by weight. Calcium chloride was dissolved in sterile distilled water and blended with White Portland cement using a water to cement ratio of 0.5. Analysis of the bioactivity and pH of white Portland cement pastes with calcium chloride added at various amounts was carried out in simulated body fluid. Setting time, density, compressive strength and volume of permeable voids were also investigated. The characteristics of cement pastes were examined by X-ray diffractometer and scanning electron microscope linked to an energy-dispersive X-ray analyzer. The result indicated that the addition of calcium chloride could accelerate the hydration of white Portland cement, resulting in a decrease in setting time and an increase in early strength of the pastes. The compressive strength of all cement pastes with added calcium chloride was higher than that of the pure cement paste, and the addition of calcium chloride at 8 wt.% led to achieving the highest strength. Furthermore, white Portland cement pastes both with and without calcium chloride showed well-established bioactivity with respect to the formation of a hydroxyapatite layer on the material within 7 days following immersion in simulated body fluid; white Portland cement paste with added 3%CaCl2 exhibited the best bioactivity. - Highlights: ► Optimization CaCl2 content on the bioactivity and mechanical properties. ► CaCl2 was used as an addition at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10% by weight. ► CaCl2 resulted in a decrease in setting time and an increase in early strength. ► Addition of 3%CaCl2 exhibited the optimum formation of hydroxyapatite.

  2. 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.

  3. Interfacial morphology and domain configurations in 0-3 PZT-Portland cement composites

    International Nuclear Information System (INIS)

    Cement-based piezoelectric composites have attracted great attention recently due to their promising applications as sensors in smart structures. Lead zirconate titanate (PZT) and Portland cement (PC) composite were fabricated using 60% of PZT by volume. Scanning Electron Microscope and piezoresponse force microscope were used to investigate the morphology and domain configurations at the interfacial zone of PZT-Portland cement composites. Angular PZT ceramic grains were found to bind well with the cement matrix. The submicro-scale domains were clearly observed by piezoresponse force microscope at the interfacial regions between the piezoelectric PZT phase and Portland cement phase, and are clearer than the images obtained for pure PZT. This is thought to be due to the applied internal stress of cement to the PZT ceramic particle which resulted to clearer images.

  4. 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)

  5. Absorption Characteristics of Cement Combination Concrete Containing Portland Cement, fly ash, and Metakaolin

    Directory of Open Access Journals (Sweden)

    Folagbade S.O.

    2016-03-01

    Full Text Available The resistance to water penetration of cement combination concretes containing Portland cement (PC, fly ash (FA, and metakaolin (MK have been investigated at different water/cement (w/c ratios, 28-day strengths, and depths of water penetration using their material costs and embodied carbon-dioxide (eCO2 contents. Results revealed that, at equal w/c ratio, eCO2 content reduced with increasing content of FA and MK. MK contributed to the 28-day strengths more than FA. Compared with PC, FA reduced cost and increased the depth of water penetration, MK increased cost and reduced the depth of water penetration, and their ternary combinations become beneficial. At equal strengths and levels of resistance to water penetration, most of the cement combination concretes are more environmentally compatible and costlier than PC concrete. Only MK binary cement concretes with 10%MK content or more and ternary cement concretes at a total replacement level of 55% with 10%MK content or more have higher resistance to water penetration than PC concrete.

  6. Multi-scale simulation of capillary pores and gel pores in Portland cement paste

    OpenAIRE

    Gao, Peng; YE, guang; Wei, Jiangxiong; Yu, Qijun

    2015-01-01

    The microstructures of Portland cement paste (water to cement ratio is 0.4, curing time is from 1 day to 28 days) are simulated based on the numerical cement hydration model, HUMOSTRUC3D (van Breugel, 1991; Koenders, 1997; Ye, 2003). The nanostructures of inner and outer C-S-H are simulated by the packing of monosized (5 nm) spheres. The pore structures (capillary pores and gel pores) of Portland cement paste are established by upgrading the simulated nanostructures of C-S-H to th...

  7. Utilization of Iron Ore Tailings as Raw Material for Portland Cement Clinker Production

    Directory of Open Access Journals (Sweden)

    Li Luo

    2016-01-01

    Full Text Available The cement industry has for some time been seeking alternative raw material for the Portland cement clinker production. The aim of this research was to investigate the possibility of utilizing iron ore tailings (IOT to replace clay as alumina-silicate raw material for the production of Portland cement clinker. For this purpose, two kinds of clinkers were prepared: one was prepared by IOT; the other was prepared by clay as a reference. The reactivity and burnability of raw meal, mineralogical composition and physical properties of clinker, and hydration characteristic of cement were studied by burnability analysis, differential thermal analysis, X-ray diffraction, and hydration analysis. The results showed that the raw meal containing IOT had higher reactivity and burnability than the raw meal containing clay, and the use of IOT did not affect the formation of characteristic mineralogical phases of Portland cement clinker. Furthermore, the physical and mechanical performance of two cement clinkers were similar. In addition, the use of IOT was found to improve the grindability of clinker and lower the hydration heat of Portland cement. These findings suggest that IOT can replace the clay as alumina-silicate raw material for the preparation of Portland cement clinker.

  8. EFFECT OF NATURAL ZEOLITE ON THE COMPRESSIVE STRENGTH AND FREEZE-THAW RESISTANCE OF PORTLAND CEMENT

    OpenAIRE

    Bayartsetseg, E.; Lkhagvajargal, G.; Batgerel, D.; Sarangerel, D.; Ochirkhuyag, B

    2011-01-01

    Effects of zeolites in various natural deposits as replacement cementing material on mechanical performance of Portland cement were studied. The blended cement pastes with zeolites were cured at room temperature in air for various durations (1, 7 and 28 days). Mechanical performance of the blended cement samples such as setting time, volume of water, compressive strength, normal consistency and freeze-thaw resistance of the mortar are determined. The optimal substitution ratio was 20 wt. % of...

  9. 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. PMID:26615227

  10. A comparative evaluation of compressive strength of Portland cement with zinc oxide eugenol and Polymer-reinforced cement: An in vitro analysis

    Directory of Open Access Journals (Sweden)

    S Prakasam

    2014-01-01

    These samples were further subdivided based on time interval and were tested at 1 hour, 24 hours and at 7 th day. After each period of time all the specimens were tested by vertical CVR loaded frame with capacity of 5 tones/0473-10kan National Physical laboratory, New Delhi and the results were statistically analyzed using ANOVA and Scheffe test. Results: Polymer-reinforced cement with 50% Portland cement, Zinc oxide with 50% Portland cement, Polymer-reinforced cement with 25% Portland cement and Zinc oxide with 25% Portland cement exhibited higher compressive strength when compared to Zinc oxide with 0% Portland cement and Polymer-reinforced cement with 0% Portland cement, at different periods of time. The difference between these two groups were statistically significant (P < 0.05 and it is suggested that mixture of 50% and 25% Portland cement in Zinc oxide eugenol and Polymer-modified zinc oxide cement can be used as core build up material and permanent filling material. Conclusion: It is concluded that 50% and 25% Portland cement in zinc oxide eugenol and polymer-modified zinc oxide eugenol results in higher compressive strength and hence can be used as permanent filling material and core built-up material.

  11. Chemical Composition and Microstructure of Hydration Products of Hardened White Portland Cement Pastes Containing Admixtures

    Institute of Scientific and Technical Information of China (English)

    LI Qiu

    2015-01-01

    This study investigated the nature of hydration products of white portland cement (WPC) containing 20 mM malic acid or 1 M calcium chloride hydrated for 11 years. The study identiifed the hydration products and characterized the chemical composition, morphology, micro/nano structure of C-S-H and the main binding phase in cementitious materials. Calcium hydroxide (CH), ettringite and C-S-H were identiifed in WPC with 20 mM malic acid paste hydrated for 11 years. WPC with 1 M calcium chloride paste hydrated for 11 years contained the same phases, but with less CH, and the presence of Friedel’s salt (Ca2Al(OH)6Cl·2H2O). There were still small amount of anhydrous cement particles remaining in both pastes after 11 years hydration according to the SEM and29Si MAS NMR results. The hydration products of paste containing malic acid had a lower porosity than those prepared with calcium chloride upon visual inspection under SEM. The morphology of the outer product (Op) C-S-H was coarse ifbrillar and the inner product (Ip) C-S-H had a very ifne microstructure in both pastes under TEM. Both Ip and Op C-S-H formed in paste containing malic acid had lower Ca/Si and higher Al/Si than those in paste containing calcium chloride. C-S-H in paste containing calcium chloride had longer MCL and less percentage of bridging tetrahedra occupied by aluminum in silicon/aluminum chains due to relatively lessQ1 and moreQ2. A new type of silicon tetrahedra,Q2B, was introduced during deconvolution of29Si MAS NMR results. Ip and Op C-S-H in both pastes had aluminum substituted tobermorite-type and jennite-type structure, and all the charges caused by aluminum substituting silicon bridging tetrahedra were balanced by Ca2+.

  12. 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.

  13. Hydrolitical equilibrium of hydrates of portland cement, part 1

    International Nuclear Information System (INIS)

    Based on the basic principles of thermodynamics the present report (Part 1) provides a contribution to thermodynamically favoured stable states of the most important hydrated compounds of portland cement. An extensive literature search was made to find the related thermodynamic data for the data-base. According to our calculations even at room temperature the C-S-H-Gel is not the thermodynamically most stable end product of hydrated calcium silicates. The most stable products might be Hillebrandit, Foshagit, 11A Tobermorit or Gyrolit. It is generally agreed, that the cubic hydrate C3AH6 is the stable end product of calcium aluminate hydrates. Our calculations lead to the same results. By sulfates we have found, that at lower temperatures Ettringit is the stable phase, but at higher temperatures the corresponding monosulfate is more stable. Ettringit is not stable relative to C3AH6 even in its water solutions. Ettringit is also not stable relative to Friedl's salt. More information could be found in Part 2 of this report (in preparation). 46 figs., 13 refs., 18 tabs. (Authors)

  14. 13C chemical shift anisotropies for carbonate ions in cement minerals and the use of 13C, 27Al and 29Si MAS NMR in studies of Portland cement including limestone additions

    International Nuclear Information System (INIS)

    13C isotropic chemical shifts and chemical shift anisotropy parameters have been determined for a number of inorganic carbonates relevant in cement chemistry from slow-speed 13C MAS or 13C(1H) CP/MAS NMR spectra (9.4 T or 14.1 T) for 13C in natural abundance. The variation in the 13C chemical shift parameters is relatively small, raising some doubts that different carbonate species in Portland cement-based materials may not be sufficiently resolved in 13C MAS NMR spectra. However, it is shown that by combining 13C MAS and 13C(1H) CP/MAS NMR carbonate anions in anhydrous and hydrated phases can be distinguished, thereby providing valuable information about the reactivity of limestone in cement blends. This is illustrated for three cement pastes prepared from an ordinary Portland cement, including 0, 16, and 25 wt.% limestone, and following the hydration for up to one year. For these blends 29Si MAS NMR reveals that the limestone filler accelerates the hydration for alite and also results in a smaller fraction of tetrahedrally coordinated Al incorporated in the C-S-H phase. The latter result is more clearly observed in 27Al MAS NMR spectra of the cement–limestone blends and suggests that dissolved aluminate species in the cement–limestone blends readily react with carbonate ions from the limestone filler, forming calcium monocarboaluminate hydrate. -- Highlights: •13C chemical shift anisotropies for inorganic carbonates from 13C MAS NMR. •Narrow 13C NMR chemical shift range (163–171 ppm) for inorganic carbonates. •Anhydrous and hydrated carbonate species by 13C MAS and 13C(1H) CP/MAS NMR. •Limestone accelerates the hydration for alite in Portland – limestone cements. •Limestone reduces the amount of aluminium incorporated in the C-S-H phase

  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. X-ray diffractometry of steam cured ordinary Portland and blast-furnace-slag cements

    International Nuclear Information System (INIS)

    This work studies some aspects of the phases produced by hydration of ordinary and blast-furnace-slag cements, at normal conditions and steam cured (60 and 950 C), using an X-ray diffraction technique. The blast-furnace-slag cement was a mixture of 50% of ordinary Portland cement and 50% of blast-furnace-slag (separately grinding). After curing the X-ray diffraction reveals that, in relation to ordinary Portland cement, the main phases in blast-furnace-slag cement are hydrated silicates and aluminates, hydro garnet, etringitte and mono sulphate. After steam curing the hydration of blast-furnace-slag cement proceeds. This is a result of the slag activation by the curing temperature. (author). 8 refs., 3 figs., 1 tab

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

    OpenAIRE

    Jovanović Nataša; Komljenović Miroslav; Petrašinović-Stojkanović Ljiljana; Baščarević Zvezdana; Bradić Violeta; Rosić Aleksandra

    2006-01-01

    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 amount...

  18. Various durability aspects of calcined Kaolin-blended Portland cement pastes and concretes

    OpenAIRE

    SAILLIO, Mickael; BAROGHEL BOUNY, Véronique; PRADELLE, Sylvain

    2015-01-01

    The use of calcined clay, in the form of metakaolin (MK), as a pozzolanic constituent for concrete has received considerable attention in recent years, due to the lower CO2 emission of this supplementary cementitious material compared to the production of a classic portland cement. Furthermore, concretes incorporating MK show some improve durability properties. In this paper, the durability of concretes and cement pastes with MK as partial replacement of cement (10 and 25%) has been investiga...

  19. 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.

  20. Design and manufacture of Portland cement Application of statistical analysis

    OpenAIRE

    Svinning, Ketil

    2011-01-01

    The purpose of the work is to enable design and manufacture of cement with emphasis on the quality and the properties of cement. Data used in the design and manufacture were collected from predictions of properties and characteristics of cement. The properties of cement were predicted from its characteristics and from the production conditions in cement kiln and mill. The cement characteristics were in some investigations predicted from the production conditions. The design was based on sensi...

  1. Enhancement of cemented waste forms by supercritical CO{sub 2} carbonation of standard portland cements

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, J.B.; Carey, J.; Taylor, C.M.V.

    1997-08-01

    We are conducting experiments on an innovative transformation concept, using a traditional immobilization technique, that may significantly reduce the volume of hazardous or radioactive waste requiring transport and long-term storage. The standard practice for the stabilization of radioactive salts and residues is to mix them with cements, which may include additives to enhance immobilization. Many of these wastes do not qualify for underground disposition, however, because they do not meet disposal requirements for free liquids, decay heat, head-space gas analysis, and/or leachability. The treatment method alters the bulk properties of a cemented waste form by greatly accelerating the natural cement-aging reactions, producing a chemically stable form having reduced free liquids, as well as reduced porosity, permeability and pH. These structural and chemical changes should allow for greater actinide loading, as well as the reduced mobility of the anions, cations, and radionuclides in aboveground and underground repositories. Simultaneously, the treatment process removes a majority of the hydrogenous material from the cement. The treatment method allows for on-line process monitoring of leachates and can be transported into the field. We will describe the general features of supercritical fluids, as well as the application of these fluids to the treatment of solid and semi-solid waste forms. some of the issues concerning the economic feasibility of industrial scale-up will be addressed, with particular attention to the engineering requirements for the establishment of on-site processing facilities. Finally, the initial results of physical property measurements made on portland cements before and after supercritical fluid processing will be presented.

  2. Enhancement of cemented waste forms by supercritical CO2 carbonation of standard portland cements

    International Nuclear Information System (INIS)

    We are conducting experiments on an innovative transformation concept, using a traditional immobilization technique, that may significantly reduce the volume of hazardous or radioactive waste requiring transport and long-term storage. The standard practice for the stabilization of radioactive salts and residues is to mix them with cements, which may include additives to enhance immobilization. Many of these wastes do not qualify for underground disposition, however, because they do not meet disposal requirements for free liquids, decay heat, head-space gas analysis, and/or leachability. The treatment method alters the bulk properties of a cemented waste form by greatly accelerating the natural cement-aging reactions, producing a chemically stable form having reduced free liquids, as well as reduced porosity, permeability and pH. These structural and chemical changes should allow for greater actinide loading, as well as the reduced mobility of the anions, cations, and radionuclides in aboveground and underground repositories. Simultaneously, the treatment process removes a majority of the hydrogenous material from the cement. The treatment method allows for on-line process monitoring of leachates and can be transported into the field. We will describe the general features of supercritical fluids, as well as the application of these fluids to the treatment of solid and semi-solid waste forms. some of the issues concerning the economic feasibility of industrial scale-up will be addressed, with particular attention to the engineering requirements for the establishment of on-site processing facilities. Finally, the initial results of physical property measurements made on portland cements before and after supercritical fluid processing will be presented

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

    DEFF Research Database (Denmark)

    Moesgaard, M; Poulsen, Søren Lundsted; Herfort, D; Steenberg, M; Kirkegaard, L F; Skibsted, Jørgen; Yue, Y

    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)....

  4. 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.......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....

  5. 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.

  6. 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.

  7. 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

  8. 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 ettringite (Ca(6)Al(2)(SeO(4))(3)(OH)(12).26H(2)O), respectively. PMID:19339110

  9. 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.

  10. Immobilisation of strontium, nickel and iodide by a sulphate-resisting Portland cement

    International Nuclear Information System (INIS)

    The interaction of Sr(II), Ni(II) and I(-I) with sulphate-resisting Portland cement was investigated under highly alkaline conditions. Batch-sorption studies were performed by contacting HTS cement (haute teneur en silice, sulphate-resisting Portland cement, Lafarge, France) with artificial cement pore water (ACW). The composition of ACW was 0.18 M KOH, 0.114 M NaOH and 1.2 mM Ca(OH)2. 85Sr, 63Ni and 125I were used as tracers. In the experiments with Sr(II) and Ni(II), isosaccharinic acid (ISA) was added to ACW at 10-5 M to 10-2 M in order to study the effect of complexing ligands on radionuclide retention. The stability of the tracer solutions and the cement suspensions were first assessed. Moreover, the inventory of the stable elements were determined in cement and cement pore water. We then studied the kinetics of the radionuclide-cement interaction process and measured the dependence of the distribution ratio (Rd) on the concentration of ISA and on the concentration of cement particles (S:L ratio). In the case of 63Ni and 125I a strong decrease in the distribution ratio (Rd) with increasing S:L ratio was observed. There is strong indication that the inventory of the stable fraction of an element present in cement pore water accounts for the retention of the radioisotope fraction. The results further indicate that phase transformations may occur in non-pre-equilibrated cement systems (non-equilibrium conditions) which affect 63Ni uptake by HTS cement. The distribution ratios measured on HTS cement were compared with values obtained from measurements on important cement components (portlandite, CSH/C(A)SH-phases)

  11. Hydration and microstructure of Portland cement partially substituted with ultrafine silica

    OpenAIRE

    J. I. Escalante; Gómez-Zamorano, L. Y.

    2009-01-01

    Geothermal waste, a by-product of steam power plants that use geothermal underground resources, was studied as a possible replacement for Portland cement. This waste consists primarily in amorphous nanometric silica with traces of sodium and potassium chlorides. The replacement ratios studied were 0, 10 and 20% in cements cured at 20 and 60 ºC. X-ray diffraction analysis showed that clinker phase hydration took place earlier in the presence of the geothermal waste. Scanning electron microscop...

  12. DURABILITY PERFORMANCE OF RFCC SPENT CATALYSTBLENDED PORTLAND CEMENT PASTE EXPOSED TO SEA WATER ATTACK

    OpenAIRE

    Allahverdi A.; Mahdavan M.

    2013-01-01

    This paper discusses the performance of the paste of Portland cement blended with spent catalyst from Resid Fluidized Catalytic Cracking (RFCC) unit of petroleum refining processes in sea water. 28-day cured paste specimens prepared from binary cement mixes containing different amounts of spent catalyst were exposed to Persian Gulf sea water. Compressive strength, weight, and length changes of the specimens were monitored and considered for evaluating the extent of deterioration. Laboratory t...

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

    Directory of Open Access Journals (Sweden)

    Riccardo Ricceri

    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. 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.

  15. STUDY OF AMMONIA SOURCE AT A PORTLAND CEMENT PRODUCTION PLANT (JOURNAL VERSION)

    Science.gov (United States)

    A source and process sampling study was conducted at a dry process Portland Cement production plant. One aspect of the study focused on the source or point of NH3 within the production process. An extensive number of process solids from raw feeds to baghouse solids were collected...

  16. 78 FR 10005 - National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing...

    Science.gov (United States)

    2013-02-12

    ... Reporting Tool FR Federal Register gr/dscf grains per dry standard cubic foot HAP hazardous air pollutants... Information Document. On July 18, 2012 (77 FR 42368), the EPA proposed to amend the Portland cement... A. PM Parametric Monitoring B. Scaling for Continuous Parametric Monitoring of THC for...

  17. 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.

  18. Thermal analysis of borogypsum and its effects on the physical properties of Portland cement

    International Nuclear Information System (INIS)

    Borogypsum, which consists mainly of gypsum crystals, B2O3 and some impurities, is formed during the production of boric acid from colemanite, which is an important borate ore. In this study, the effect of borogypsum and calcined borogypsum on the physical properties of ordinary Portland cement (OPC) has been investigated. The calcination temperature and transformations in the structures of borogypsum and natural gypsum were determined by differential thermal analysis (DTA), thermogravimetric analysis (TGA) and X-ray diffraction (XRD) techniques. Thermal experiments were carried out between ambient temperature and 500 deg. C in an air atmosphere at a heating rate of 10 deg. C min-1. After calculation of enthalpy and determination of conversion temperatures, borogypsum (5% and 7%), hemihydrate borogypsum (5%) and natural gypsum (5%) were added separately to Portland cement clinker and cements were ground in the laboratory. The final products were tested for chemical analysis, compressive strength, setting time, Le Chatelier expansion and fineness properties according to the European Standard (EN 196). The results show that increasing the borogypsum level in Portland cement from 5% to 7% caused an increase in setting time and a decrease in soundness expansion and compressive strength. The cement prepared with borogypsum (5%) was found to have similar strength properties to those obtained with natural gypsum, whereas a mixture containing 5% of hemihydrate borogypsum was found to develop 25% higher compressive strength than the OPC control mixtures at 28 days. For this reason, utilization of calcined borogypsum in cement applications is expected to give better results than untreated borogypsum. It is concluded that hemihydrate borogypsum could be used as a retarder for Portland cement as an industrial side. This would play an important role in reducing environmental pollution

  19. Immobilisation Of Spent Ion Exchange Resins Using Portland Cement Blending With Organic Material

    International Nuclear Information System (INIS)

    Immobilisation of spent ion exchange resins (spent resins) using Portland cement blending with organic material for example bio char was investigated. The performance of cement-bio char matrix for immobilisation of spent ion exchange resins was evaluated based on their compression strength and leachability under different experimental conditions. The results showed that the amount of bio char and spent resins loading effect the compressive strength of the waste form. Several factors affecting the leaching behaviour of immobilised spent resins in cement-bio char matrix. (author)

  20. 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

    represents a potential alternative to traditional SCMs, used for reduction of the CO2 emission associated with cement production. It is found that the NCAS glass takes part in the hydration reactions after about two weeks of hydration and a degree of reaction of approx. 50 % is observed after 90 days of......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...... 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...

  1. Study irradiation damage by fast neutrons in Portland cement by means of ultra-sound

    International Nuclear Information System (INIS)

    The effect of neutron irradiation in samples of Portland cement paste was evaluated, using the resonance frequency method and pulse velocity of ultra-sound technique. The samples were divide in three groups: 1) Monitoring samples; 2) Samples to gamma heating simulation; 3) Fast neutron irradiated samples in reactor core. Santa Rita Portland cement was utilized for samples preparation with water-cement rate of 0,40 l/kg. The irradiation was performed in the research reactor IEA-R1, at IPEN-CNEN/SP, with an integrated flux of 7,2 X 10 sup(18) n/cm sup(2) (E approx. 1 Mev). The samples of group 2 were submitted to special micro-waves heat treatment-with the same number of cycles of the reactor-which allowed the detection of fast neutron radiation effects within the predominant thermal effects. (author)

  2. Reverse extraction of early-age hydration kinetic equation from observed data of Portland cement

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The early-age hydration of Portland cement paste has an important impact on the formation of microstructure and development of strength.However,manual derivation of hydration kinetic equation is very difficult because there are multi-phased,multi-sized and interrelated complex chemical and physical reactions during cement hydration.In this paper,early-age hydration kinetic equation is reversely extracted automatically from the observed time series of hydration degree of Portland cement using evolutionary computation method that combines gene expression programming and particle swarm optimization algorithms.In order to reduce the computing time,GPUs are used for acceleration in parallel.Studies have shown that according to the extracted kinetic equation,simulation curve of early-age hydration is in good accordance with the observed experimental data.Furthermore,this equation still has a good generalization ability even changing chemical composition,particle size and curing conditions.

  3. Properties of Portland-Composite Cements with metakaolin: Commercial and manufactured by Thermal Activation of Serbian Kaolin Clay

    Directory of Open Access Journals (Sweden)

    Mitrovic A.

    2012-09-01

    Full Text Available Portland-composite cements (CEM II were prepared with addition of 5 to 35% of metakaolin (MK, manufactured by thermal activation/calcination of Serbian kaolin clay, and commercial matakaolin (CMK. Performance of the composite cements was evaluated, through the setting time (initial and final, compressive strengths (for ages 2, 7, 28, 90 and 180 days and soundness, and compared with control cement (Portland cement – CEM I. Setting time (initial and final is accelerated in Portlandcomposite cements, for both metakaolins used. The acceleration is higher in cement with addition of commercial metakaolin. Lower compressive strength is obtained after 2 days of curing for all Portland-composite cements in comparison with control cement, since pozzolanic reaction still did not show its effect. After 7 days, pozzolanic reaction show its effect, manifested as compressive strength increase of Portland-composite cements with addition of up to 35% of CMK, and 25% in the case of cements with MK. After 28 days compressive strength was higher than that for control cement for cements prepared with addition of CMK, and with addition of up to 25% MK. After 90 days increased compressive strength was noticed with addition of 10 - 20% of CMK, and with 10 and 15% of MK, while after 180 days addition of both metakaolins influences compressive strength decrease. The results of the soundness, 0.5 mm for CEM I, and 1.0 mm in most Portland-composite cements indicate soundness increase with addition of metakaolins. Generally, better performance of Portland-composite cements was obtained with addition of commercial metakaolin, which may be attributed to the differences in the pozzolanic activity of the applied metakaolins, 20.5 MPa and 14.9 MPa for CMK and MK, respectively. By our previous findings pozzolanic activity of the thermally activated clay may be increased by subsequent milling of the metakaolin manufactured by thermal activation process.

  4. 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

  5. Experimental and modeling study of Portland cement paste degradation in boric acid

    International Nuclear Information System (INIS)

    In the framework of Spent Fuel Pools (SFP) lifetime studies, an investigation of the Portland cement degradation in boric acid has been requested by the Electric Power Research Institute. The main goal of this study is to identify the physico-chemical degradation mechanisms involved in boric acid media. Both experimental and modeling approaches are considered. Concerning degradation experiments, sample of cement paste are immersed during three and nine months in a boric acid solution at 2400 ppm that is periodically renewed. Boric acid concentration has been chosen to be representative of SFP solution. Results will be confronted with reactive transport numerical calculations performed by the reactive transport code HYTEC associated with a dedicated extended database called Thermoddem. The analysis of degradation solution revealed a main ions release mechanism driven by diffusion especially for calcium, nitrate, sodium and sulfate. Leaching behavior of magnesium seems to be more complex. Decalcification is the major degradation process involved, even if a non-negligible contribution of further cations (Mg2+, Na+) and anions (SO42-) has been noticed. Analysis of degradation soution also revealed that kinetic of Portland cement paste degradation in boric acid is higher than in pure water, regarding the degraded depths measured and calcium leaching rate. This observation has been confirmed by solid characterization. Microstructure analysis of degraded Portland cement paste showed a global porosity increase in the degraded zone that might be mainly attributed to Portlandite dissolution. An Ettringite reprecipitation in the degraded zone has been suspected but could also be Ettringite-like phases containing boron. The analysis techniques used did not allow us to differentiate it, and no others specific mineral phases containing boron has been identified. Profile pattern by XRD analysis allowed us to identify four zones composing the degraded Portland cement paste

  6. 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%.

  7. Ordinary Portland Cement matrix for solidification of cellulosic protective clothes hazardous wastes

    International Nuclear Information System (INIS)

    The used cellulosic protective clothes constitutes considerable fraction of the hazardous and radioactive wastes accumulated during the practical daily life. The direct solidification of these wastes with ordinary Portland cement resulted in waste forms having undesired characters, therefore, it is recommended to immobilize the secondary waste solutions coming from the oxidative degradation of the used protective clothes waste simulates rather than direct imbedding. IR analyses, X-ray diffraction and thermal characteristics for products of both direct encapsulation of the waste and the cementation of its degradation products were performed to evaluate the properties of the final waste cemented form before their disposal. Based on the results reached from X-ray diffraction, IR spectrograms and thermal analyses reports, it could be stated that no detectable changes in hydration and curing coarse of ordinary Portland cement when mixing the residual secondary waste solution resulting from the oxidative degradation of the used protective clothes waste simulate compared with mixing cement with water and in reverse with imbedding the unprocessed waste in cement matrix

  8. Compressive Strength and Hydration Process of Self Compacting Concrete (SCC) mixed with Sea Water, Marine Sand and Portland Composite Cement

    OpenAIRE

    Tjaronge, Wihardi; Irmawaty, Rita

    2014-01-01

    In order to eliminate the main problems of shortage of clean water and fine aggregate in the low land areas and the distant islands, this research utilized sea water and marine sand and Portland composite cement to produce high performance of Self Compacting Concrete (SCC). Portland composite cement containing of fly ash. The evaluation result on the mix design, workability (slumpflow, segregation), mechanical properties (compressive strength-static modulus) and hydration process of SCC were ...

  9. The influence of shrinkage-cracking on the drying behaviour of White Portland cement using Single-Point Imaging (SPI).

    Science.gov (United States)

    Beyea, S D; Balcom, B J; Bremner, T W; Prado, P J; Cross, A R; Armstrong, R L; Grattan-Bellew, P E

    1998-11-01

    The removal of water from pores in hardened cement paste smaller than 50 nm results in cracking of the cement matrix due to the tensile stresses induced by drying shrinkage. Cracks in the matrix fundamentally alter the permeability of the material, and therefore directly affect the drying behaviour. Using Single-Point Imaging (SPI), we obtain one-dimensional moisture profiles of hydrated White Portland cement cylinders as a function of drying time. The drying behaviour of White Portland cement, is distinctly different from the drying behaviour of related concrete materials containing aggregates. PMID:9875607

  10. 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.

  11. 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.

  12. Radiopacity evaluation of Portland and MTA-based cements by digital radiographic system

    Directory of Open Access Journals (Sweden)

    Alvaro Henrique Borges

    2011-06-01

    Full Text Available OBJECTIVE: The aim of the present study was to evaluate the radiopacity of Portland and MTA-based cements using the Digora TM digital radiographic system. MATERIAL AND METHODS: The performed tests followed specification number 57 from the American National Standard Institute/American Dental Association (2000 for endodontic sealing materials. The materials were placed in 5 acrylic plates, especially designed for this experiment, along with a graduated aluminum stepwedge varying from 1 to 10 mm in thickness. The set was radiographed at a 30 cm focus-object distance and with 0.2 s exposure time. After the radiographs were taken, the optical laser readings of radiographs were performed by Digora TM system. Five radiographic density readings were performed for each studied material and for each step of the aluminum scale. RESULTS: White ProRoot MTA (155.99±8.04, gray ProRoot MTA (155.96±16.30 and MTA BIO (143.13±16.94 presented higher radiopacity values (p<0.05, while white non-structural Portland (119.76±22.34, gray Portland (109.71±4.90 and white structural Portland (99.59±12.88 presented lower radiopacity values (p<0.05. CONCLUSIONS: It was concluded that MTA-based cements were the only materials presenting radiopacity within the ANSI/ADA specifications.

  13. 谈硅酸盐水泥的强度%On strength of Portland cement

    Institute of Scientific and Technical Information of China (English)

    牛崇霞

    2012-01-01

    The paper illustrates the formation and development of the cement strength,analyzes the factors which influence the strength of the Portland cement from the mineral components of the clinker,the cement fineness,and the construction conditions,and points out the cement strength could adhere to the regulation of the relative standards only by controlling these factors in a strict way.%简要阐述了水泥强度的产生与发展,从熟料的矿物组成、水泥细度、施工条件三方面分析了影响硅酸盐水泥强度的因素,指出只有严格控制这些因素,才能保证水泥强度符合有关标准规定。

  14. Analysis by X-Ray images of EVA waste incorporated in Portland Cement

    International Nuclear Information System (INIS)

    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)

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

    OpenAIRE

    Kara, P; Csetényi, L; Borosnyói, A

    2014-01-01

    In several countries, waste glass causes environmental concerns as quantities stockpiled exceed recycling in the packaging stream. Being amorphous and having relatively high silicium and calcium contents, glass is pozzolanic or even cementitious, when finely ground. Reducing particle sizes typically to less than 100 µm may give control over the alkali-silica reaction in concrete, therefore making this material a possible substitute to Portland cement. Such use may moderate the problem of dump...

  16. Early and Late Strength Characterization of Portland Cement Containing Calcined Low-Grade Kaolin Clay

    OpenAIRE

    Mark Bediako; Gawu, S. K. Y.; A. A. Adjaottor; John Solomon Ankrah

    2016-01-01

    Heat treated low-grade kaolin clays are now considered as a suitable pozzolanic material to metakaolins. However their suitability as a good pozzolanic material depends on the geochemistry and structure of the clay which is usually influenced by the geographical environment. This study investigated a low-grade kaolin clay from Nyamebekyere in the Ashanti Region of Ghana. The influence of the calcined material on the early and late strength development of Portland cement was analyzed. The earl...

  17. Influence of cellulose ethers on the kinetics of early Portland cement hydration

    OpenAIRE

    Müller, Ingo

    2006-01-01

    The phase-specific influence of cellulose ether (CEs) on Portland cement hydration was investigated in-situ, using synchrotron X-ray diffractometry. CE-caused retardation can be traced to the polymers adsorption behaviour. The adsorption decreases in following order: silicates and their hydrates (high), sulfates (low), ettringite (zero). The retarding effect is strong on silicates, moderate on sulfates and unspecific on alluminates.

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

    OpenAIRE

    Evandro Tolentino; Fernando S. Lameiras; Abdias M. Gomes; Cláudio A. Rigo da Silva; Wander L. Vasconcelos

    2002-01-01

    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...

  19. 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

    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......, 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...

  20. 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.

  1. 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.

  2. 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.

  3. Development of Portland cement for orthopedic applications, establishing injectability and decreasing setting times.

    Science.gov (United States)

    Wynn-Jones, Gareth; Shelton, Richard M; Hofmann, Michael P

    2012-11-01

    The injectability of Portland cement (PC) with calcium chloride and calcium nitrate additives was investigated using a syringe with a 2 mm aperture for potential clinical applications such as vertebroplasty. Addition of either additive at 10 wt % increased the quantity of cement extruded through the syringe from approximately 25 wt % for the PC standard, to over 95 wt %. 10 wt % additions of either additive also decreased setting times from over 2 h to below 25 min. The compressive strength of the modified cements was all greater than the compressive strength of a human vertebral body. Decreasing either additive to 5 wt % generated compressive strengths after 24 h setting equal to polymethylmethacrylate, the cement used for the majority of vertebroplasty procedures. An initial early exotherm in the chloride cements was coupled with an X-ray diffraction (XRD) peak that indicated the early formation of the ettringite cement phase. In contrast, Fourier transform infrared (FTIR) spectroscopy and XRD data indicated that calcium nitrate may have stimulated early calcium silicate hydrate (C-S-H) production (the main strength producing phase of PC). Combining the two additives produced a synergistic effect with cements having increased injectabilities and compressive strengths compared with either addition used individually. This study has demonstrated that by modifying PC with nonproprietary chemicals it was possible to significantly increase cement injectability and reduce setting times whilst maintaining compressive strengths, making PC suitable for potential orthopedic applications. PMID:22887643

  4. 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. PMID:23864828

  5. 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.

  6. Ettringite and C-S-H Portland cement phases for waste ion immobilization: A review

    International Nuclear Information System (INIS)

    The formation, structure and chemistry of the ettringite and C-S-H phases of Portland cement have been reviewed as they relate to waste ion immobilization. The purpose of this review was to investigate the use of Portland cement as a host for priority metallic pollutants as identified by the Environmental Protection Agency and as a host for radioactive waste ions as identified in 40 CFR 191. Ettringite acts as host to a number of these ions in both the columnar and channel sections of the crystal structure. Substitutions have been made at the calcium, aluminum, hydroxide and sulfate sites. C-S-H also hosts a number of the waste species in both ionic and salt form. Immobilization mechanisms for C-S-H include sorption, phase mixing and substitution. The following ions have not apparently been reported as specifically immobilized by one of these phases: Ag, Am, Np, Pu, Ra, Tc, Th and Sn; however, some of these ions are immobilized by Portland cement

  7. Possibility of using waste tire rubber and fly ash with Portland cement as construction materials.

    Science.gov (United States)

    Yilmaz, Arin; Degirmenci, Nurhayat

    2009-05-01

    The growing amount of waste rubber produced from used tires has resulted in an environmental problem. Recycling waste tires has been widely studied for the last 20 years in applications such as asphalt pavement, waterproofing systems and membrane liners. The aim of this study is to evaluate the feasibility of utilizing fly ash and rubber waste with Portland cement as a composite material for masonry applications. Class C fly ash and waste automobile tires in three different sizes were used with Portland cement. Compressive and flexural strength, dry unit weight and water absorption tests were performed on the composite specimens containing waste tire rubber. The compressive strength decreased by increasing the rubber content while increased by increasing the fly ash content for all curing periods. This trend is slightly influenced by particle size. For flexural strength, the specimens with waste tire rubber showed higher values than the control mix probably due to the effect of rubber fibers. The dry unit weight of all specimens decreased with increasing rubber content, which can be explained by the low specific gravity of rubber particles. Water absorption decreased slightly with the increase in rubber particles size. These composite materials containing 10% Portland cement, 70% and 60% fly ash and 20% and 30% tire rubber particles have sufficient strength for masonry applications. PMID:19110410

  8. Ageing of portland cement concrete cured under moist conditions

    OpenAIRE

    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 chloride diffusion coefficient, in the laboratory is rapid chloride migration (RCM) Test. With this test, the resistance of concrete to chloride ingress is evaluated. Changing losing resistance represents...

  9. 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...

  10. 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.

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

    International Nuclear Information System (INIS)

    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), 29Si and 27Al 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. - Highlights: ► This is the first study of Portland cement-based biomaterials by 27Al and 29Si NMR. ► 20 wt.% ZrO2 radiopacifier accelerates the early cement hydration reactions. ► Extent of hydration after 6 h is increased from 5.7% to 15% in the presence of ZrO2. ► Initial and final setting times are reduced by 25 and 22 min, respectively. ► ZrO2 provides nucleation sites for the precipitation of early hydration products.

  12. Utilization of Industrial Borax Wastes (BW) for Portland Cement Production

    OpenAIRE

    ELBEYLİ, İffet YAKAR

    2004-01-01

    Industrial borax wastes (BWs) are formed as solid waste during the production of borax from tincal [Na2B4O5(OH)4.8H2O] in Bandırma, Turkey. These wastes cause different environmental problems and lead to economic losses because of high boron oxide (B2O3) content. The primary aim of this study is the removal of B2O3 from BWs and the second aim is the usage of BWs with low boron content in cement as an additive material. For this purpose, the BW was treated with water for removal of b...

  13. 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.

  14. Seawater Resistance Evaluation of Existing NPP Concrete Structures Using High-sulfate Resistance Portland Cement

    International Nuclear Information System (INIS)

    For nuclear power plant(NPP) structures exposed to marine environment, low-heat and high sulfate resistance portland cement(Type V) with low content of C3A has been widely used to restrain the occurrence of chemical erosion caused by seawater. Despite the superior sulfate resistance of Type V cement, however, questions have been raised on the efficiency of Type V cement for resisting the chloride ion, which is one of the major substances found in seawater. Accordingly, the ACI 357R revised in 1984 required that Type I or II cement containing 4 ∼ 10% of C3A be used. In addition, the standard specifications of Korea Concrete Institute (KCI) were revised in 1996 in order to limit the use of Type V cement in the construction of marine concrete structures. In this regard, the mechanical properties and seawater resistance of concrete using various kinds of cement have been studied to evaluate the durability of existing NPP structures using Type V cement as well as to manifest the regulatory position for the materials of concrete. This paper presents detail observations obtained through this study

  15. Setting temperature evolution of nitrate radwaste immobilized in ordinary portland cement

    International Nuclear Information System (INIS)

    Materials based on hydraulic cements such as ordinary Portland cement (OPC) have many applications in the radioactive waste disposal field. Cement hydration process is an exothermic reaction and can cause a considerable temperature rise in the cemented waste form. Specially when large blocks of waste forms are produced it is necessary to have some information about the temperature build up which occurs inside the mass, because this effect may have some influences on the ultimate properties of the hardened cement paste. This temperature rise cause expansion while the cement paste is hardening. When the cooling process takes place, to the surrounding temperature, crackings and contractions may then occur. Whether cracking arise it depends both on the magnitude of the temperature induced stress and on the capacity of the mixture to accommodate the strain. This paper compares the temperature growth in pastes into two different geometries: one uses a waste container with 3.8 dm3 (one US gallon) capacity placed inside a 0.21 m3 (55 gallons) concrete lined drum, which acts as a radiation shielding, and the other the same container placed in ambient at room temperature. Correlations between the time of temperature occurrence, maximum temperature, the water to cement ratio and salt content were observed

  16. Reactivity of Ordinary Portland Cement (OPC) grout and various lithologies from the Harwell research site

    International Nuclear Information System (INIS)

    Ordinary Portland Cement (OPC) has been used in the completion of boreholes on the Harwell Research Site, AERE, Oxfordshire. The purpose of this study was to examine the effect of OPC and the alkaline pore fluids generated during its setting on the various lithological types encountered in the boreholes. To facilitate this, samples of core representing the various rock types were selected and cement-rock composites were prepared from these in the laboratory to simulate the borehole cements. After a curing period of 15 months the cores and associated cement plugs were examined for any signs of reactivity or bonding. The best cement-rock bonding was shown by naturally well-cemented sandstone and limestone lithologies. Although no significant chemical reaction was seen to have occurred between OPC and rock, the OPC appears able to bind onto the rock surface because of the rigidity of the rock surface. Therefore, the best cement rock bonding and seal with OPC may be expected in the limestones of the Great Oolite Group, Inferior Oolite Group and parts of the Corallian Beds. Because of the reactivity of OPC towards certain lithologies a better borehole seal in such a sedimentary sequence might be achieved using a bentonite backfill in those parts of the sequence which either react with or bond only weakly to OPC. (author)

  17. 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.

  18. Evaluation of physico-chemical properties of Portland cements and MTA

    Directory of Open Access Journals (Sweden)

    Jorge Luis Gonçalves

    2010-09-01

    Full Text Available The purpose of this study was to evaluate the hydrogenionic potential and electrical conductivity of Portland cements and MTA, as well as the amount of arsenic and calcium released from these materials. In Teflon molds, samples of each material were agitated and added to plastic flasks containing distilled water for 3, 24, 72 and 168 h. The results were analyzed with a Kruskal-Wallis non-parametric test for global comparisons and a Dunn-Tukey test for pairwise comparisons. The results revealed no significant differences in the pH of the materials (p > 0.05. The electrical conductivity of the cements were not statistically different (p > 0.05. White non-structural cement and MTA BIO released the largest amount of calcium ions into solution (p 0.05. The results indicated that the physico-chemical properties of Portland cements and MTA were similar. Furthermore, all materials produced an alkaline environment and can be considered safe for clinical use because arsenic was not released. The electrical conductivity and the amount of calcium ions released into solution increased over time.

  19. Progress in the investigation of the longevity of Portland cement grout seal materials

    International Nuclear Information System (INIS)

    The sealing of openings in underground repositories and the assessment of the potential for seal materials to perform acceptably for long periods of time are concerns shared by programs considering the deep disposal of nuclear waste. Two grouting materials, bentonite and portland cement, have been identified by many programs as likely candidate seal materials. As a part of Phase III of the Stripa Project, the longevity of both of these materials is being investigated in a series of coordinated laboratory, modeling, and field studies. Long-term performance is an important issue particularly for cement, since most solid phases in cement are metastable, and therefore it is likely that cement seal performance would degrade with time. In this investigation, geochemical and permeability modeling have been used together to estimate how long cement seals may be expected to perform acceptably. Analyses to assess cement degradation due to phase inversion and dissolution have been performed; for dissolution calculations, both slow flow and fast flow hydrologic systems have been analyzed to establish bounding conditions. Actual granitic terrain grounwater compositions ranging from fresh to saline have been used to calculate cement-groundwater interactions. A relationship between cement permeability and porosity has been developed based on empirical data. Changes in performance with time have been predicted by conservatively estimating hydrologic conditions at successive stages of post-closure repository history. For the conditions considered, preliminary results indicate that the single largest determinant of seal performance is the initial hydraulic conductivity of the cement. Based on this investigation, cement grout performance may be acceptable for very long periods of time (tens of thousands to millions of years) providing its initial conductivity is on the order of 10-12 m/s

  20. 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

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. Using portland cement for encapsulation of epipremnum aureum generated from phytoremediation process of liquid radioactive wastes

    International Nuclear Information System (INIS)

    Phyto remediation process was recommended for treatment of low and intermediate level liquid radioactive waste. Epipremnum aureum (golden pothas plant) was used to bioabsorbe, bioaccumulate and biostabilize Cs-137 and Co-60 from simulated waste solution containing both radionuclides. After the phyto remediation process, the collected golden pothas was solidified using portland cement aiming at complete and safe management scheme. In this part of work x-ray diffraction , infrared analysis and electron microscope examination as non-destructive techniques were used to evaluate the characteristics of obtained final waste forms of cemented golden pothas. In addition, mechanical, porosity and chemical optimizations were performed under various experimental parameters to asses the suitability of the two processes i.e. phyto remediation and cementation for managing these wastes categories. The experimental results obtained confirmed that encapsulation of 3 % dry ground golden pothas that collected from treatment process of radioactive waste solution, in cement materials did not affect the hydration, setting and curing of the cement matrix. In addition , the obtained cemented waste form exhibits acceptable constitutions that comply with the final disposal requirements.

  6. Evaluation of Portland cement from X-ray diffraction associated with cluster analysis

    International Nuclear Information System (INIS)

    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)

  7. Influence of The Activated Qatari Attapulgite Clay Admixture on The Mechanical Properties and Hydration Kinetics of Ordinary Portland Cement

    OpenAIRE

    Al-Noaimi, Kawkab Kh. [كوكب النعيمي

    2001-01-01

    Blended cements are types of cements containing additives other than those used m Portland cement, which have considerable technological interest, because such addition increases the chemical resistance to sulfate and chloride attack. The present investigation represents a laboratory study, which provides a unique opportunity to introduce an effective practical attempt to deal with the problem of concrete deterioration m Qatar and the Arabian Gulf region, and to provide a solution to the prob...

  8. Influence of Plasticizer Amount on Rheological and Hydration Properties of CEM II Type Portland Cements

    Science.gov (United States)

    Šeputytė-Juciké, J.; Pundienė, I.; Kičaitė, A.; Pranckevičienė, J.

    2015-11-01

    The article analyzes the effect of plasticizer (based on polycarboxilates) amount (0.3 - 1.2% wt. of cement) on the rheological and hydration properties of two Portland cements pastes: CEM II/A-S 42.5N and CEM II/A-LL 42.5N. Increase of plasticizer amount reduces viscosity of CEM II/A-LL 42.5N cement paste from 3 to 12 times, where viscosity of CEM II/A-S 42.5N cement paste reduces from 5 to 20 times. The optimum plasticizer dose (0.3%) in case of CEM II/A-S 42.5N and (1.2%) in case of CEM II/A-LL 42.5N was established. Calorimetry studies have shown that plasticizer reduces the wetting heat release rate in CEM II/A-LL 42.5N cement twice and in CEM II/A-S 42.5N cement - by 25%. Plasticizer prolongs the maximum heat release rate time by 16 h in CEM II/A-LL 42.5N samples and reduces heat release rate by 19%. In CEM II/A-S 42.5N cement samples plasticizer prolongs maximum heat release rate time by 14.5 h and increases heat release rate by 15%. The goal of this study is to analyze the effect of the dosage of the most widely used plasticizer on solubility characteristics, rheological and hydration properties of two cements CEM II/A-S 42.5N and CEM II/A-LL 42.5N to establish the optimum dose of plasticizer in cements pastes.

  9. 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.

  10. 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.

  11. Search of a prompt gamma ray for chlorine analysis in a Portland cement sample

    International Nuclear Information System (INIS)

    Prompt Gamma Ray analysis of chlorine contaminated Portland cement samples have been carried out using an accelerator-based Prompt Gamma ray Neutron Activation Analysis setup. The chlorine concentration was measured over a range of 0.25-4 wt% using 1.165 MeV capture γ-rays from chlorine. The experimental results were compared with the results of Monte Carlo simulations and an excellent agreement was observed between the two results. Further theoretical study has shown that yield of the 1.165 MeV prompt γ-rays from chlorine is not very sensitive to variation in moisture contents of the Portland sample. An order of magnitude increase in sample moisture content resulted in only 16-20% increase in yield of 1.165 MeV prompt γ-rays

  12. Search of a prompt gamma ray for chlorine analysis in a Portland cement sample

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A. [Center for Applied Physical Sciences, King Fahd University of Petroleum and Minerals, Box 1815, Dhahran-31261 (Saudi Arabia)]. E-mail: annaqvi@kfupm.edu.sa; Nagadi, M.M. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia); Kidwai, S. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia); Khateeb-ur-Rehman [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia); Maslehuddin, M. [Center for Engineering Sciences, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia)

    2004-11-11

    Prompt Gamma Ray analysis of chlorine contaminated Portland cement samples have been carried out using an accelerator-based Prompt Gamma ray Neutron Activation Analysis setup. The chlorine concentration was measured over a range of 0.25-4 wt% using 1.165 MeV capture {gamma}-rays from chlorine. The experimental results were compared with the results of Monte Carlo simulations and an excellent agreement was observed between the two results. Further theoretical study has shown that yield of the 1.165 MeV prompt {gamma}-rays from chlorine is not very sensitive to variation in moisture contents of the Portland sample. An order of magnitude increase in sample moisture content resulted in only 16-20% increase in yield of 1.165 MeV prompt {gamma}-rays.

  13. The impact of zirconium oxide nanoparticles on the hydration chemistry and biocompatibility of white Portland cement.

    Science.gov (United States)

    Li, Qiu; Deacon, Andrew D; Coleman, Nichola J

    2013-01-01

    Zirconium oxide (ZrO2) has been nominated as a radiopacifying agent for use in MTA-like Portland cement-based root-filling materials. This research examines the impact of 20 wt% ZrO2 nanoparticles in the size range 50 to 75 nm on the early hydration chemistry of white Portland cement. Nano-ZrO2 was found to accelerate the degree of hydration by 26% within the first 24 h by presenting efficient nucleation sites for the precipitation and growth of the early C-S-H gel products. The presence of nano-ZrO2 was also found to divert the fate of the aluminium-bearing reaction products by lowering the ettringite to monosulphate ratio, reducing the size of the ettringite crystals and by increasing the Al:Si ratio of the C-S-H gel phase. The chemical and microstructural changes conferred upon the cement matrix by the nano-ZrO2 particles had a positive impact on in vitro biocompatibility with respect to MG63 osteosarcoma cells (via MTT assay). PMID:24088838

  14. Structural Evaluation and Performance of Portland Cement Concretes After Exposure to High Temperatures

    Directory of Open Access Journals (Sweden)

    Evandro Tolentino

    2002-03-01

    Full Text Available We evaluated the "residual" thermal conductivity of Portland cement concretes (with characteristic compressive strength at 28 days, f ck, of 20 MPa and 50 MPa at room temperature after heat-treating at 180 °C, 300 °C and 600 °C. The description of the geometry of the structure was carried out using mercury intrusion porosimetry and nitrogen sorption. The results showed a decreasing tendency of residual thermal conductivity, which we attributed to heat-induced concrete degradation. Furthermore, the results from mercury intrusion porosimetry and nitrogen sorption tests showed that a coarser pore structure is produced with the raise of heat-treatment temperatures.

  15. Structural Evaluation and Performance of Portland Cement Concretes After Exposure to High Temperatures

    OpenAIRE

    Evandro Tolentino; Fernando S. Lameiras; Abdias M. Gomes; Cláudio A. Rigo da Silva; Wander L. Vasconcelos

    2002-01-01

    We evaluated the "residual" thermal conductivity of Portland cement concretes (with characteristic compressive strength at 28 days, f ck, of 20 MPa and 50 MPa) at room temperature after heat-treating at 180 °C, 300 °C and 600 °C. The description of the geometry of the structure was carried out using mercury intrusion porosimetry and nitrogen sorption. The results showed a decreasing tendency of residual thermal conductivity, which we attributed to heat-induced concrete degradation. Furthermor...

  16. Electromagnetic interference shielding with Portland cement paste containing carbon materials and processed fly ash

    OpenAIRE

    Zornoza, E.; Catalá, G.; Jiménez, F.; Andión, L. Gª; Garcés, P.

    2010-01-01

    The study described in this article explored the effect of adding different types of carbon materials (graphite powder and three types of carbon fibre), fly ash (with 5.6%, 15.9% and 24.3% Fe2O3), and a mix of both on electromagnetic interference (EMI) shielding in Portland cement pastes. The parameters studied included the type and aspect ratio of the carbonic material, composite material thickness, the frequency of the incident electromagnetic r...

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

    OpenAIRE

    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, 1...

  18. 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

  19. Healing of apical rarefaction of three nonvital open apex anterior teeth using a white portland cement apical plug

    Directory of Open Access Journals (Sweden)

    Amitabha Chakraborty

    2012-01-01

    Full Text Available The major challenge of performing root canal treatment in an open apex pulp-less tooth is to obtain a good apical seal. MTA has been successfully used to achieve a good apical seal, wherein the root canal obturation can be done immediately. MTA and White Portland Cement has been shown similarity in their physical, chemical and biological properties and has also shown similar outcome when used in animal studies and human trials. In our study, open apex of three non vital upper central incisors has been plugged using modified white Portland cement. 3 to 6 months follow up revealed absence of clinical symptoms and disappearance of peri-apical rarefactions. The positive clinical outcome may encourage the future use of white Portland cement as an apical plug material in case of non vital open apex tooth as much cheaper substitute of MTA.

  20. Modeling the degradation of Portland cement pastes by biogenic organic acids

    International Nuclear Information System (INIS)

    Reactive transport models can be used to assess the long-term performance of cement-based materials subjected to biodegradation. A bioleaching test (with Aspergillus niger fungi) applied to ordinary Portland cement pastes during 15 months is modeled with HYTEC. Modeling indicates that the biogenic organic acids (acetic, butyric, lactic and oxalic) strongly accelerate hydrate dissolution by acidic hydrolysis whilst their complexation of aluminum has an effect on the secondary gel stability only. The deepest degradation front corresponds to portlandite dissolution and decalcification of calcium silicate hydrates. A complex pattern of sulfate phases dissolution and precipitation takes place in an intermediate zone. The outermost degraded zone consists of alumina and silica gels. The modeling accurateness of calcium leaching, pH evolution and degradation thickness is consistently enhanced whilst considering increase of diffusivity in the degraded zones. Precipitation of calcium oxalate is predicted by modeling but was hindered in the bioleaching reactor.

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

    International Nuclear Information System (INIS)

    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)

  2. A combined QXRD/TG method to quantify the phase composition of hydrated Portland cements

    Energy Technology Data Exchange (ETDEWEB)

    Soin, Alexander V.; Catalan, Lionel J.J. [Department of Chemical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1 (Canada); Kinrade, Stephen D., E-mail: stephen.kinrade@lakeheadu.ca [Department of Chemistry, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1 (Canada)

    2013-06-15

    A new method is reported for quantifying the mineral phases in hydrated cement pastes that is based on a combination of quantitative X-ray diffractometry (QXRD) and thermogravimetry (TG). It differs from previous methods in that it gives a precise measure of the amorphous phase content without relying on an assumed stoichiometric relationship between the principal hydration products, calcium hydroxide (CH) and calcium silicate hydrate (C–S–H). The method was successfully applied to gray and white ordinary Portland cements (GOPC and WOPC, respectively) that were cured for up to 56 days. Phase distributions determined by QXRD/TG closely matched those from gray-level analysis of backscattered scanning electron microscope (BSEM) images, whereas elemental compositions obtained for the amorphous phase by QXRD/TG agreed well with those measured by quantitative energy dispersive X-ray spectroscopy (EDS)

  3. Plant-Wide Energy Efficiency Assessment at the Arizona Portland Cement Plant in Rillito, Arizona

    Energy Technology Data Exchange (ETDEWEB)

    Stephen J. Coppinger, P.E.; Bruce Colburn, Ph.D., P.E., CEM

    2007-05-17

    A Department of Energy Plant-wide Assessment was undertaken by Arizona Portland Cement (APC) beginning in May 2005. The assessment was performed at APC’s cement production facility in Rillito, Arizona. The assessment included a compressed air evaluation along with a detailed process audit of plant operations and equipment. The purpose of this Energy Survey was to identify a series of energy cost savings opportunities at the Plant, and provide preliminary cost and savings estimates for the work. The assessment was successful in identifying projects that could provide annual savings of over $2.7 million at an estimated capital cost of $4.3 million. If implemented, these projects could amount to a savings of over 4.9 million kWh/yr and 384,420 MMBtu/year.

  4. 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)

  5. Study on the hydration and microstructure of Portland cement containing diethanol-isopropanolamine

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Suhua, E-mail: yc982@163.com; Li, Weifeng; Zhang, Shenbiao; Hu, Yueyang; Shen, Xiaodong

    2015-01-15

    Diethanol-isopropanolamine (DEIPA) is a tertiary alkanolamine used in the formulation of cement grinding-aid additives and concrete early-strength agents. In this research, isothermal calorimetry was used to study the hydration kinetics of Portland cement with DEIPA. A combination of X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC)–thermogravimetric (TG) analysis and micro-Raman spectroscopy was used to investigate the phase development in the process of hydration. Mercury intrusion porosimetry was used to study the pore size distribution and porosity. The results indicate that DEIPA promotes the formation of ettringite (AFt) and enhances the second hydration rate of the aluminate and ferrite phases, the transformation of AFt into monosulfoaluminate (AFm) and the formation of microcrystalline portlandite (CH) at early stages. At later stages, DEIPA accelerates the hydration of alite and reduces the pore size and porosity.

  6. 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.

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

    Science.gov (United States)

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

    2016-01-01

    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. PMID:27347987

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

    Science.gov (United States)

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

    2016-01-01

    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. PMID:27347987

  9. Increase in the strength characteristics of Portland cement due to introduction of the compound mineral supplements

    Science.gov (United States)

    Il'ina, Liliia; Gichko, Nikolai; Mukhina, Irina

    2016-01-01

    At the initial phase of hardening it is the limestone component that plays a major role in the hardening process, which acts as the substrate for the crystallization of hydrate tumors due to its chemical affinity with the products of Portland cement hydration. After 7 days, the diopside supplement influences the processes more significantly. Diopside has a high modulus of elasticity compared to the cement paste. As a result, stresses are redistributed within the cement paste and the whole composition is hardened. An increase in the quantity of diopside in the compound supplement to more than 66.7% does not provide a substantial increase in the strength of the cement paste. As the hardness of diopside is higher than the hardness of limestone, much more energy is required to grind it down to a usable component. Therefore, a further increase in the quantity of diopside in the compound supplement is not economically feasible. An evaluation of the optimum quantity of input compound mineral supplements can be made based on the ideas of close packing of spherical particles and the Pauling rules. The optimum content of the supplement is 8-8.5% provided that its dispersion and density are close to the dispersion and density of the binder. An increase in the dispersion of the supplement reduces its optimal quantity.

  10. Solidification of spent radioactive organic solvent by sulfoaluminate and Portland cements

    International Nuclear Information System (INIS)

    The solidification of simulated spent radioactive organic solvent, tri-butyl phosphate/kerosene, was investigated by emulsification–solidification method using sulfoaluminate cement (SAC) and Portland cement (PC). Zeolite, calcium hydroxide and MR-1 type emulsifier were mixed into the cement blends for improving the performance of solidified waste forms (SWF). The properties of SWF were evaluated in terms of mechanical strength, leachability and mineral phase analyses. The hydration products of SWF were characterized by X-ray diffraction (XRD). The experimental results showed that the 28 d compressive strengths of SAC solidified waste forms (SACF) and PC solidified waste forms (PCF) were 14.23 and 19.07 MPa, respectively. Leaching sequence of three radionuclides in two kinds of SWF is Cs+ > Sr2+ > Co2+. Compared with PCF, SACF had better performance in preventing nuclides Co2+ and Cs+ from leaching to the environment. The XRD patterns suggested that simulated spent radioactive organic solvent and emulsifier in SWF did not obviously change the hydration products of the two cements (SAC and PC). (author)

  11. 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.

  12. 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

  13. Individual and combined effects of chloride, sulfate, and magnesium ions on hydrated Portland-cement paste

    International Nuclear Information System (INIS)

    Ground water with a high concentration of magnesium ion is known to cause deterioration to portland cement concretes. A proposed mechanism for this deterioration process published previously involves an approximate 1:1 replacement of Ca ions by Mg ions in the crystalline phases of hydrated cement. The current study was undertaken to determine which ions, among magnesium, chloride, and sulfate, cause deterioration; whether their deleterious action is individual or interdependent; and to relate this mechanism of deterioration to the outlook for a 100-yr service life of concretes used in mass placements at the Waste Isolation Pilot Plant. Loss of Ca ion by cement pastes was found to be strongly related to the concentration of Mg ion in simulated ground-water solutions in which the paste samples were aged. This was true of both salt- containing and conventional cement pastes. No other ion in the solutions exerted a strong effect on Ca loss. Ca ion left first from calcium hydroxide in the pastes, depleting all calcium hydroxide by 60 days. Some calcium silicate hydrate remained even after 90 days in the solutions with the highest concentration of Mg ion, while the paste samples deteriorated noticeably. The results indicated a mechanism that involves dissolution of Ca phases and transport of Ca ions to the surface of the sample, followed by formation of Mg-bearing phases at this reaction surface rather than directly by substitution within the microstructure of hydrated cement. Given that calcium hydroxide and calcium silicate hydrate are the principal strength-giving phases of hydrated cement, this mechanism indicates the likelihood of significant loss of integrity of a concrete exposed to Mg-bearing ground water at the WIPP. The rate of deterioration ultimately will depend on Mg-ion concentration, the microstructure materials of the concrete exposed to that groundwater, and the availability of brine

  14. Estimation of longevity of portland cement grout using chemical modeling techniques

    International Nuclear Information System (INIS)

    Portland cement has been identified as a likely candidate seal material by programs investigating the deep burial of nuclear waste as a disposal mechanism. The longevity of performance of cement grout is currently being investigated, along with bentonite, under the auspices of the Stripa Project. Coordinated laboratory, field, and modeling studies are underway to produce fundamental data, practical experience, and estimates of long-range performance, respectively. Long-term performance of cement grout is of particular concern. Since most of the solid phases of which grout is comprised are metastable, it is likely that grout performance will decrease with time. The question is whether performance will still be acceptable after this decrease. This issue is being addressed with the coupled use of geochemical and permeability modeling. For a simplified cement system, two mechanisms for chemical degradation have been considered: phase change and dissolution. For dissolution, both equilibrium (slow flow) and open (fast flow) systems have been analyzed as bounding scenarios. Granitic terrain groundwaters ranging from fresh to saline have been used in the analyses. To assess the consequences in terms of flow, an empirical relation between cement permeability and porosity has been developed. Performance changes with time have been predicted by making conservative estimates of local hydraulic head conditions for successive periods of repository history. For the granitic rock environments considered, preliminary results indicate that cement grout performance may be acceptable for tens of thousands to millions of years, providing its initial hydraulic conductivity is on the order of 10-12 m/s. Other conditions favoring long-term performance include minimizing the ettringite content of the grout, and emplacement at a site where the groundwater has an elevated TDS, and where the local hydraulic gradient is flat or repository resaturation times are short

  15. Mechanical characterization of Portland cement mortars containing petroleum or coal tar

    Directory of Open Access Journals (Sweden)

    Garcés, P.

    2007-08-01

    Full Text Available This article discusses experimental data on the flexural and compressive strength of Portland cement mortars containing additions or cement replacements consisting in petroleum or coal tar, by-products of the oil and coal industries. The materials studied were two coal (BACA and BACB and two petroleum (BPP and BPT tars. The results show that it is feasible to use such materials as a partial replacement for cement in mortar manufacture. This should lead to the design of a new sustainable product that will contribute to lowering the environmental impact of construction materials while at the same time opening up an avenue for the re-use of this type of industrial by-products.En este artículo se presentan datos experimentales de resistencia a flexión y a compresión de morteros de cemento Portland con adición y sustitución de breas de petróleo y de alquitrán de carbón, que son subproductos de la industria del carbón o del petróleo. Los materiales estudiados son breas de alquitrán de carbón A (BACA y B (BACB, y dos breas de petróleo (BPP y (BPT. Los datos demuestran la viabilidad del uso de estas breas en la fabricación de morteros con menores contenidos de cemento, permitiendo diseñar un nuevo material sostenible con el medio ambiente y que contribuya a reducir el impacto ambiental de los materiales de construcción, hecho que permite abrir una nueva vía de valorización de estos subproductos.

  16. 76 FR 34252 - Notice Pursuant to the National Cooperative Research and Production Act of 1993; Portland Cement...

    Science.gov (United States)

    2011-06-13

    ... Cooperative Research and Production Act of 1993, 15 U.S.C. 4301 et seq. (``the Act''), Portland Cement... published a notice in the Federal Register pursuant to Section 6(b) of the Act on February 5, 1985 (50 FR... in the Federal Register pursuant to Section 6(b) of the Act on March 7, 2011 (76 FR 12370)....

  17. 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

  18. Determination of absorption length of CO2 and high power diode laser radiation for ordinary Portland cement

    OpenAIRE

    Lawrence, Jonathan; Johnston, Emma P.; Li, Lin

    2000-01-01

    The laser beam absorption lengths of CO2 and a high power diode laser (HPDL) radiation for the ordinary Portland cement (OPC) surface of concrete have been determined. By employing Beer-Lambert’s law the absorption lengths for concrete of CO2 and a HPDL radiation were 470±22 μm and 177±15 μm respectively.

  19. 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.

  20. The chemistry and expansion of limestone - Portland cement mortars exposed to sulphate containing solutions

    International Nuclear Information System (INIS)

    Some concretes in sulphate-bearing groundwaters can deteriorate slowly through chemical reactions which cause expansion and stress. The overall process involves diffusion of sulphate into the concrete, chemical reaction with some cement constituents, internal expansion and, finally, physical disruption of the reacted zone. This work addresses the chemical reactions and the expansion resulting from them so that the overall process of sulphate attack can be modelled eventually. The extent and rate of reaction of calcium sulphate with ordinary and sulphate resisting Portland cements (OPC and SRPC) have been measured under various conditions. Additionally, mortar bars were fabricated from OPC, OPC/BFS (blast furnace slag) and SRPC cements with carboniferous limestone and exposed to various sulphate-containing solutions. The linear expansion of the bars was continuously monitored over a period of about 200 days and, after exposure, the bars were analysed in detail. The results show that the bulk expansion during sulphate attack is proportional to sulphur taken up in insoluble ettringite and magnesium (when present) precipitated as brucite. The results are used to rationalise the behaviour of concretes in sulphate-bearing environments. (author)

  1. 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.

  2. 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.

  3. DURABILITY PERFORMANCE OF RFCC SPENT CATALYSTBLENDED PORTLAND CEMENT PASTE EXPOSED TO SEA WATER ATTACK

    Directory of Open Access Journals (Sweden)

    Allahverdi A.

    2013-12-01

    Full Text Available This paper discusses the performance of the paste of Portland cement blended with spent catalyst from Resid Fluidized Catalytic Cracking (RFCC unit of petroleum refining processes in sea water. 28-day cured paste specimens prepared from binary cement mixes containing different amounts of spent catalyst were exposed to Persian Gulf sea water. Compressive strength, weight, and length changes of the specimens were monitored and considered for evaluating the extent of deterioration. Laboratory techniques of X-ray diffractometry, scanning electron microscopy, and Energy dispersive X-ray spectroscopy were also used to study the deteriorated specimens. The results confirm that at relatively high replacement levels, the pozzolanic property of the spent catalyst and the increased open pore volume of such blended cements may result in contradictory consequences. Specimens of relatively higher replacement levels exhibit higher rates of deterioration in spite of their superior mechanical strength behavior caused by pozzolanic reaction. The results obtained by X-ray diffractometry confirm the presence of higher amounts of chlorine-containing Friedel’s salt in specimens containing RFCC spent catalyst compared to plain reference specimens.

  4. Some aspects about the Portland cement utilization as a matrix for radioactive waste immobilization

    International Nuclear Information System (INIS)

    More recently, the environmental policy has concentrated the focus on the study of the waste disposal environmental impact. Since Portland cement is commonly used as a matrix in the low-and intermediate-level radioactive waste immobilization, in the present work, some relationships between the structure and properties of matrix, based on available concrete technology information, has been established by using the multi-level approach analysis. The relationships were developed based on hydrating reactions, the microstructure models, the pore system. It have been verified that: a) CSH gel is responsible for the cementing action and for the strength; b) it seems that the capillary porosity is the strength limiting; c) the permeability, regarded in terms of gel porosity and reduced capillary porosity of the hardened cement paste, may not be a decisive factor for the radionuclide release; d) the shrinkage and the swelling induced cracks can enhance the diffusion mechanism for the cracks increase the exposed surface. The durability of the waste disposal matrix concerning chemical attack in the acidic environment has been considered. (author)

  5. 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.

  6. Geochemistry of Wellbore Integrity in CO2 Sequestration: Portland Cement-Steel-Brine-CO2 Interactions (Invited)

    Science.gov (United States)

    Carey, J. W.

    2013-12-01

    Effective geologic sequestration of CO2 requires long-term storage with very low leak rates. Numerous studies have identified wells as one of the key risk factors for CO2 leakage including purpose-built injection and monitoring wells in addition to older wells in and above the storage reservoir. All wells have the potential to leak due to faulty construction or other defects. However, geochemical reactions induced by CO2 could result in damage to Portland cement and steel that are used in the well to isolate reservoir fluids from underground drinking water sources and the surface. This concern is based on the thermodynamic incompatibility of CO2-saturated aqueous fluids with Portland cement and steel, which leads to relatively rapidly reactions that form, principally, calcium carbonate and iron carbonate. Despite this thermodynamic fate, wellbore materials perform and maintain zonal isolation in field and experimental observations. This is understood as a consequence of coupled behavior between flow of reactants (CO2-water) and the rate of dissolution and precipitation of cement or corrosion of steel. In the restricted flow environments found in wellbore systems, cements are carbonated but do not suffer significant deterioration of hydrologic or mechanical properties. In fact, cement carbonation often results in reduced permeability and enhanced mechanical strength. While steel is susceptible to corrosion, wellbore environments allow development of protective iron carbonate scale. In addition, the presence of Portland cement, even carbonated cement, provides protection against significant rates of corrosion. The impact of geochemical reactions in the wellbore environment cannot be separated from coupled flow, thermal and mechanical processes. CO2-induced chemical reactions migrating upward from a storage reservoir will not result in the creation of defects or the wholesale dissolution of cement or steel. Defects must exist that allow CO2×brine to flow and to come

  7. 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.

  8. Chemical and morphological characteristics of mineral trioxide aggregate and Portland cements.

    Science.gov (United States)

    Khan, Shahbaz; Kaleem, Muhammad; Fareed, Muhammad Amber; Habib, Amir; Iqbal, Kefi; Aslam, Ayesha; Ud Din, Shahab

    2016-01-01

    The purpose of this study was to investigate the chemical composition and particle morphology of white mineral trioxide aggregate (WMTA) and two white Portland cements (CEM 1 and CEM 2). Compositional analysis was performed by energy dispersive X-ray spectroscopy, X-ray fluorescence spectrometry and X-ray diffraction whereas, morphological characteristics were analyzed by scanning electron microscope and Laser scattering particle size distribution analyzer. The elemental composition of WMTA, CEM 1 and CEM 2 were similar except for the presence of higher amounts of bismuth in WMTA. Calcium oxide and silicon oxide constitute the major portion of the three materials whereas, tricalcium silicate was detected as the major mineral phase. The particle size distribution and morphology of WMTA was finer compared to CEM 1 and CEM 2. The three tested materials had relatively similar chemical composition and irregular particle morphologies. PMID:26830831

  9. 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.

  10. 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.

  11. 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. PMID:25966327

  12. Hydration kinetics for the alite, belite, and calcium aluminate phase in Portland cements from 27Al and 29Si MAS NMR spectroscopy

    DEFF Research Database (Denmark)

    Skibsted, Jørgen; Jensen, Ole Mejlhede; Jakobsen, Hans Jørgen

    1997-01-01

    29Si magic-angle spinning (MAS) NMR spectroscopy is shown to be a valuable tool for obtaining the quantities of alite and belite in hydrated Portland cements. The hydration (1-180 days) of a white Portland cement with 10 wt.% silica fume added is investigated and the degrees of hydration for alit...... belite, and silica fume are determined. It is demonstrated that 27Al MAS NMR spectra of hydrated Portland cements can give quantitative information about the formation of ettringite and the conversion of this phase to monosulphate during hydration....

  13. Incorporation of trace elements in Portland cement clinker: Thresholds limits for Cu, Ni, Sn or Zn

    International Nuclear Information System (INIS)

    This paper aims at defining precisely, the threshold limits for several trace elements (Cu, Ni, Sn or Zn) which correspond to the maximum amount that could be incorporated into a standard clinker whilst reaching the limit of solid solution of its four major phases (C3S, C2S, C3A and C4AF). These threshold limits were investigated through laboratory synthesised clinkers that were mainly studied by X-ray Diffraction and Scanning Electron Microscopy. The reference clinker was close to a typical Portland clinker (65% C3S, 18% C2S, 8% C3A and 8% C4AF). The threshold limits for Cu, Ni, Zn and Sn are quite high with respect to the current contents in clinker and were respectively equal to 0.35, 0.5, 0.7 and 1 wt.%. It appeared that beyond the defined threshold limits, trace elements had different behaviours. Ni was associated with Mg as a magnesium nickel oxide (MgNiO2) and Sn reacted with lime to form a calcium stannate (Ca2SnO4). Cu changed the crystallisation process and affected therefore the formation of C3S. Indeed a high content of Cu in clinker led to the decomposition of C3S into C2S and of free lime. Zn, in turn, affected the formation of C3A. Ca6Zn3Al4O15 was formed whilst a tremendous reduction of C3A content was identified. The reactivity of cements made with the clinkers at the threshold limits was followed by calorimetry and compressive strength measurements on cement paste. The results revealed that the doped cements were at least as reactive as the reference cement.

  14. Calculation of radiation attenuation coefficients in Portland cements mixed with silica fume, blast furnace slag and natural zeolite

    International Nuclear Information System (INIS)

    This paper presents the radiation attenuation coefficients expressed as mass attenuation coefficients for Portland cement, zeolite, blast furnace slag, silica fume and their mixed types in function of the Photon energy over the energy range of 1 keV to 2 MeV. It was observed that different percentages of constituents in cement and cement mixed with different additives such as zeolite, silica fume and blast furnace slag, lead to significant variations in total mass attenuation coefficients. The elemental compositions of samples were analyzed using a wavelength dispersive XRF spectrometer. The calculated values of total mass attenuation coefficients were discussed on the basis of different percentages of constituents of cement and cement mixed with different additives

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

    International Nuclear Information System (INIS)

    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 MgCl2, NaCl, NaCl + MgCl2, MgSO4 + MgCl2 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

  16. 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.

  17. Detailed characterization of current North American portland cements and clinkers and the implications for the durability of modern concrete

    Science.gov (United States)

    Arjunan, P.

    The current study has been undertaken with a view to rationalize the relation between the cement characteristics and concrete properties with the fresh set of data collected from the North American portland cements. The important chemical and physical characteristics of the cement discussed are (a) chemical analysis, (b) phase calculations, (c) various particle characterizations and (d) rheological properties. The important concrete properties discussed are (a) alkali silica reactivity, (b) sulfate attack, (c) delayed ettringite formation (d) chloride ion permeability and (e) compressive strength. Relationship between the cement characteristics and concrete durability was determined using regression methods. The heat of hydration was mainly influenced by the variation in C 3A, SO3, equivalent Na2O contents, and fineness of portland cements. When there was no variation in C3A, SO 3, and fineness, the hydration kinetics of the cement was mainly controlled by the silicate phase hydration. The 7-day hydration was negatively correlated to C2S or C4AF content. As the C2S or C 4AF content increased, the 7-day heat of hydration decreased. C 3S content showed a positive correlation to 1 and 7-day heats of hydration, but significant negative correlation to 14 and 28-day hydration. Equivalent alkalis showed a strong positive correlation to ASR at 2 weeks. SO3 content of portland cement also showed a positive correlation to ASR expansion. A strong negative correlation was observed between C4AF content of portland cement and sulfate attack expansion at 4 and 6 months of exposure. The correlation to sulfate attack was stronger when the ratios of C3A/C4AF were taken into account. C3A content exhibited a negative correlation to chloride ion permeability. This correlation decreased as the curing period increased. SO 3 content also exhibited a negative correlation to the chloride ion permeability. Only alkalis showed a strong negative correlation to the compressive strength after 3

  18. Thermal model for rotary kiln used in the production of Portland cement clinker; Modelo termico para forno rotativo utilizado para produzir clinquer de cimento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, Vanisa C.; Menon, Genesio J.; Silva, Rogerio J. [Escola Federal de Engenharia de Itajuba, MG (Brazil). Dept. de Mecanica

    1998-07-01

    This paper presents a heat transfer model for a rotary kiln used for producing clinker of Portland cement. The temperatures will depend only on position throughout length of the kiln and time. It has been considered the heat loss through wall and the transferred heat to the solids. The finite element method has been utilized on a one-dimensional representation basis. From the results obtained it was possible to evaluate the kiln behavior, as starting point for a study of co-incineration of waste. (author)

  19. Hydration and microstructure of Portland cement partially substituted with ultrafine silica

    Directory of Open Access Journals (Sweden)

    Escalante, J. I.

    2009-12-01

    Full Text Available Geothermal waste, a by-product of steam power plants that use geothermal underground resources, was studied as a possible replacement for Portland cement. This waste consists primarily in amorphous nanometric silica with traces of sodium and potassium chlorides. The replacement ratios studied were 0, 10 and 20% in cements cured at 20 and 60 ºC. X-ray diffraction analysis showed that clinker phase hydration took place earlier in the presence of the geothermal waste. Scanning electron microscopy, in turn, revealed a reduction in porosity and intense calcium hydroxide consumption as a result of the pozzolanic reaction. The pastes containing 20% waste, however, an intense cracking was observed due to the formation of alkali silica reaction gel and ettringite. Cracking was more prominent at 60 ºC but was not observed in either the neat cement or the blend with 10 % waste. The presence of these detrimental phases was attributed to the formation of Friedel’s salt in the initial hydration stages, induced by the chlorides in the geothermal material.Se investigaron pastas de cemento Portland sustituido con un desecho geotérmico, subproducto de la generación de electricidad en plantas que emplean recursos geotérmicos. El desecho está compuesto principalmente de sílice amorfa de tamaño nanométrico, con cloruros de sodio y potasio. Se investigaron cementos con niveles de substitución de 0, 10 y 20%, curados a 20 y 60 °C. En presencia del desecho geotérmico, se observó por Difracción de rayos X cuantitativa que la hidratación de las fases del clínker se aceleró; además mediante microscopía electrónica de barrido se encontró una disminución en la porosidad y un intenso consumo de hidróxido de calcio por la reacción puzolánica. Sin embargo, para pastas con 20% de desecho geotérmico, se observó agrietamiento con la presencia de gel de reacción álcali sílice y ettringita; fue más acentuado a 60 °C y no se observó para pastas de

  20. 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

  1. 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

  2. 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.

  3. 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

  4. Microstructure and Engineering Properties of Alkali Activated Fly Ash -as an environment friendly alternative to Portland cement

    OpenAIRE

    Ma, Y.

    2013-01-01

    Alkali activated fly ash (AAFA), also named “geopolymer”, has emerged as a novel engineering material in the construction industry. This material is normally formed by the reaction between fly ash and aqueous hydroxide or alkali silicate solution. With proper mix design, AAFA can present comparable or superior engineering properties to Portland cement. Moreover, this material shows great potential for sustainable development since its production has a significantly lower CO2 emission than the...

  5. A review of the methods used to study biocompatibility of Portland cement-derived materials used in dentistry

    OpenAIRE

    Camilleri, Josette

    2006-01-01

    Advanced restorative dentistry may necessitate the need for surgical intervention to the infected root apex. Once access to the root end is achieved, the root apex is resected and filled with a dental restorative material. The materials currently in use are not satisfactory due to inadequate biocompatibility and failure to achieve desirable properties in an aqueous environment. With the introduction of a new material, essentially Portland cement used in the building industry, these desirable ...

  6. ENERGY, ACOUSTICS AND ENVIRONMENTAL SUSTAINABILITY ANALYSIS OF BUILDING SYSTEMS BASED ON WOOD WOOL MINERALIZED WITH PORTLAND CEMENT

    OpenAIRE

    Pavarin, Cora

    2014-01-01

    In the present work various aspects of the energetic, thermal and acoustic properties of porous materials with wood wool mineralized Portland cement have been analyzed, in cooperation with the company Celenit Srl, a manufacturer of panels for building insulation. These products are also recognized interesting and desirable for their environmental sustainability through specific certifications. Remind that sustainability means "development that meets the needs of the present without comprom...

  7. In vitro sealing ability of white and gray mineral trioxide aggregate (MTA and white Portland cement used as apical plugs

    Directory of Open Access Journals (Sweden)

    Patrícia Zanatta Aranha Coneglian

    2007-06-01

    Full Text Available This study evaluated the sealing ability of apical plugs made of white and gray MTA-Angelus® and white Portland cement placed via the root canal and having different thicknesses (2, 5 and 7 mm. Ninety extracted human single-rooted teeth were instrumented using a size 40 K-file to standardize the foraminal opening by the stepback technique. The teeth were assigned to 3 groups (n=30, according to the material used for fabrication of the apical plugs: A = gray MTA; B = white MTA; C = white Portland cement. The groups were subdivided into groups of 10 teeth each according to the apical plug thickness (2, 5 and 7 mm. Marginal apical dye leakage was assessed using 0.2% Rhodamine B solution in which the specimens were immersed for 72 hours at 37ºC. The roots were sectioned longitudinally in a buccolingual direction for apical plug exposure, and digital photographs were taken and analyzed by Image Tool image-analysis software. Data were analyzed statistically by Kruskal-Wallis and Dunn's tests. Significance level was set at 5%. The least percent leakage was observed for 5- and 7-mm-thick plugs (p0.05 was found between gray MTA and white Portland cement. Among the three materials analyzed, white MTA presented the highest marginal leakage (p<0.05. The findings of the present study showed that gray MTA and Portland cement had better sealing ability than white MTA when used as apical plugs. Dye leakage was smaller for 5- and 7-mm-thick plugs compared to 2-mm-thick plugs.

  8. 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.

  9. A comparative evaluation of compressive strength of Portland cement with zinc oxide eugenol and Polymer-reinforced cement: An in vitro analysis

    OpenAIRE

    S.Prakasam; Prakasam Bharadwaj; S C Loganathan; B Krishna Prasanth

    2014-01-01

    Objective: The purpose of this study is to evaluate the ultimate compressive strength of 50% and 25% Portland cement mixed with Polymer-reinforced zinc oxide eugenol and zinc oxide eugenol cement after 1 hour, 24 hours, and 7 days. Materials and Methods: One hundred and eighty samples were selected. The samples were made cylindrical of size 6 × 8 mm and were divided into six groups as follows with each group consisting of 10 samples. Group 1: Polymer-reinforced zinc oxide eugenol with...

  10. Degradation of normal portland and slag cement concrete under load, due to reinforcement corrosion

    International Nuclear Information System (INIS)

    The corrosion of reinforcement is one of the major degradation mechanisms of reinforced concrete elements. The majority of studies published on concrete-steel corrosion have been conducted on unstressed specimens. Structural concrete, however, is subjected to substantial strain near the steel reinforcing bars that resist tensile loads, which results in a system of microcracks. This report presents the initial results of an investigation to determine the effect of applied load and microcracking on the rate of ingress of chloride ion and corrosion of steel in concrete. Simply-supported concrete beam specimens were loaded to give a maximum strain of about 600 με on the tension face. Chloride ion ingress on cores taken from loaded specimens was monitored using energy-dispersive X-ray analysis techniques. Corrosion current and rate measurements using linear polarization electrochemical techniques were also obtained on the same loaded specimens. Variables investigated included two concrete types, two steel cover-depths, three applied load levels, bonded and unbonded rebars and the exposure of tension and compression beam faces to chloride solution. One concrete mixture was made with type 10 Portland cement, the other with 75% blast furnace slag, 22% type 50 cement and 3% silica fume. The rate of chloride ion ingress into reinforced concrete, and hence the time for chloride ion to reach the reinforcing steel, is shown to be dependent on applied load and the concrete quality. The dependence of corrosion process descriptors - passive layer formation, initiation period and propagation period - on the level of applied load is discussed. (Author) (6 refs., 3 tabs., 10 figs.)

  11. Nanostructural Deformation Analysis of Calcium Silicate Hydrate in Portland Cement Paste by Atomic Pair Distribution Function

    Directory of Open Access Journals (Sweden)

    Hiroshi Suzuki

    2016-01-01

    Full Text Available The deformation of nanostructure of calcium silicate hydrate (C-S-H in Portland cement (PC paste under compression was characterized by the atomic pair distribution function (PDF, measured using synchrotron X-ray diffraction. The PDF of the PC paste exhibited a unique deformation behavior for a short-range order below 2.0 nm, close to the size of the C-S-H globule, while the deformation for a long-range order was similar to that of a calcium hydroxide phase measured by Bragg peak shift. The compressive deformation of the C-S-H nanostructure was comprised of three stages with different interactions between globules. This behavior would originate from the granular nature of C-S-H, which deforms with increasing packing density by slipping the interfaces between globules, rearranging the overall C-S-H nanostructure. This new approach will lead to increasing applications of the PDF technique to understand the deformation mechanism of C-S-H in PC-based materials.

  12. Effect of temperature on the hydration of Portland cement blended with siliceous fly ash

    International Nuclear Information System (INIS)

    The effect of temperature on the hydration of Portland cement pastes blended with 50 wt.% of siliceous fly ash is investigated within a temperature range of 7 to 80 °C. The elevation of temperature accelerates both the hydration of OPC and fly ash. Due to the enhanced pozzolanic reaction of the fly ash, the change of the composition of the C–S–H and the pore solution towards lower Ca and higher Al and Si concentrations is shifted towards earlier hydration times. Above 50 °C, the reaction of fly ash also contributes to the formation of siliceous hydrogarnet. At 80 °C, ettringite and AFm are destabilised and the released sulphate is partially incorporated into the C–S–H. The observed changes of the phase assemblage in dependence of the temperature are confirmed by thermodynamic modelling. The increasingly heterogeneous microstructure at elevated temperatures shows an increased density of the C–S–H and a higher coarse porosity. -- Highlights: •The reaction of quartz powder at 80 °C strongly enhances the compressive strength. •Almost no strength increase of fly ash blended OPC at 80 °C was found after 2 days. •Siliceous hydrogarnet is formed upon the reaction of fly ash at high temperatures. •Temperature dependent change of the system was simulated by thermodynamic modelling. •Destabilisation of ettringite above 50 °C correlates with sulphate content of C–S–H

  13. Effect of temperature on the hydration of Portland cement blended with siliceous fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Deschner, Florian, E-mail: florian.deschner@gmail.com [Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Concrete and Construction Chemistry, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Lothenbach, Barbara; Winnefeld, Frank [Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Concrete and Construction Chemistry, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Neubauer, Jürgen [GeoZentrum Nordbayern, Mineralogy, University of Erlangen-Nuremberg, 91054 Erlangen (Germany)

    2013-10-15

    The effect of temperature on the hydration of Portland cement pastes blended with 50 wt.% of siliceous fly ash is investigated within a temperature range of 7 to 80 °C. The elevation of temperature accelerates both the hydration of OPC and fly ash. Due to the enhanced pozzolanic reaction of the fly ash, the change of the composition of the C–S–H and the pore solution towards lower Ca and higher Al and Si concentrations is shifted towards earlier hydration times. Above 50 °C, the reaction of fly ash also contributes to the formation of siliceous hydrogarnet. At 80 °C, ettringite and AFm are destabilised and the released sulphate is partially incorporated into the C–S–H. The observed changes of the phase assemblage in dependence of the temperature are confirmed by thermodynamic modelling. The increasingly heterogeneous microstructure at elevated temperatures shows an increased density of the C–S–H and a higher coarse porosity. -- Highlights: •The reaction of quartz powder at 80 °C strongly enhances the compressive strength. •Almost no strength increase of fly ash blended OPC at 80 °C was found after 2 days. •Siliceous hydrogarnet is formed upon the reaction of fly ash at high temperatures. •Temperature dependent change of the system was simulated by thermodynamic modelling. •Destabilisation of ettringite above 50 °C correlates with sulphate content of C–S–H.

  14. Simultaneous Differential Scanning Calorimetry and Thermogravimetric Analysis of Portland Cement as a Function of Age

    Science.gov (United States)

    Trník, Anton; Scheinherrová, Lenka; Kulovaná, Tereza; Černý, Robert

    2016-01-01

    We study the hydration and pozzolanic reactions of an ordinary Portland cement as a function of age, using the differential scanning calorimetry and thermogravimetry. The measurements are done for 2 days, 7 days, 28 days, 90 days, 180 days, and 360 days cured samples in order to monitor the rate of hydration. The investigation is performed in the temperature range from 25° C to 1000° C with a heating rate 5° C {\\cdot} min^{-1} in an argon atmosphere. The temperature, enthalpy, and mass change during the decomposition of calcium silicate hydrate gels, ettringite, portlandite, vaterite, and calcite are determined, and the changes in the portlandite amount are estimated in dependence on the time of hydration. We found out that the temperature and enthalpy of liberation of physically bound water, C-S-H gels and ettringite decomposition (all occurring from 50° C to 250° C) and Portlandite decomposition (420° C to 530° C) decrease with hydration time of studied samples. On the other hand, vaterite and calcite decomposition (530° C to 850° C) the temperature varies and the enthalpy increases with hydration time of samples.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Multiple determinations of isotope diffusion in cementitious backfills and Ordinary Portland Cement (OPC) monoliths

    International Nuclear Information System (INIS)

    The full text of publication follows: The UK concept for geological disposal of intermediate level (ILW) and low level waste (LLW) includes backfill materials based on admixtures of Ordinary Portland Cement (OPC). It is expected that the evolution of these backfill materials will generate high pH conditions and the corrosion of the metal canisters used for disposal will promote a low Eh environment. This combination of conditions within the near field of the Geological Disposal Facility (GDF) will reduce the solubility of many radionuclides and retard migration. In addition, sorption to some of the cementitious phases may contribute significantly to the retardation of many radionuclides. It is clearly important to understand how diffusion of radionuclides contributes to the overall migration from the repository. However, it remains practically difficult to isolate the effect of diffusion from other processes such as sorption and advection which may also occur in the near field and far fields of the GDF. This presentation describes a series of experiments undertaken to evaluate the diffusion of a selection of relevant radionuclides in saturated backfills (including the NIREX reference vault backfill, NRVB) and OPC matrices. The experiments build upon a significant number of related sorption studies previously undertaken by the radiochemistry group at Loughborough University and complement a series of small scale advection experiments also being undertaken. The experimental technique uses small pre-cast blocks (monoliths) of the matrix under investigation. An appropriate concentration of the isotope of interest is introduced in a cavity in the centre of the block, which is then sealed, and finally, placed in a solution previously equilibrated with the matrix. The increase in concentration of the isotope in the external solution is then determined at defined time intervals. The interpretation of the results is undertaken with methods conventionally used for geological

  1. Permeability predictions for sand-clogged Portland cement pervious concrete pavement systems.

    Science.gov (United States)

    Haselbach, Liv M; Valavala, Srinivas; Montes, Felipe

    2006-10-01

    Pervious concrete is an alternative paving surface that can be used to reduce the nonpoint source pollution effects of stormwater runoff from paved surfaces such as roadways and parking lots by allowing some of the rainfall to permeate into the ground below. This infiltration rate may be adversely affected by clogging of the system, particularly clogging or covering by sand in coastal areas. A theoretical relation was developed between the effective permeability of a sand-clogged pervious concrete block, the permeability of sand, and the porosity of the unclogged block. Permeabilities were then measured for Portland cement pervious concrete systems fully covered with extra fine sand in a flume using simulated rainfalls. The experimental results correlated well with the theoretical calculated permeability of the pervious concrete system for pervious concrete systems fully covered on the surface with sand. Two different slopes (2% and 10%) were used. Rainfall rates were simulated for the combination of direct rainfall (passive runoff) and for additional stormwater runoff from adjacent areas (active runoff). A typical pervious concrete block will allow water to pass through at flow rates greater than 0.2 cm/s and a typical extra fine sand will have a permeability of approximately 0.02 cm/s. The limit of the system with complete sand coverage resulted in an effective system permeability of approximately 0.004 cm/s which is similar to the rainfall intensity of a 30 min duration, 100-year frequency event in the southeastern United States. The results obtained are important in designing and evaluating pervious concrete as a paving surface within watershed management systems for controlling the quantity of runoff. PMID:16563606

  2. Effect of additives on the compressive strength and setting time of a Portland cement

    Directory of Open Access Journals (Sweden)

    Desirée Freitas Mryczka Machado

    2010-06-01

    Full Text Available Improvements in strength and setting time of Portland cements (PC are needed to enhance their performance as endodontic and load bearing materials. This study sought to enhance the compressive strength and setting time of a PC by adding one of the following additives: 20% and 30% poly-methylmethacrylate (PMMA, 20% and 30% irregular and spherical amalgam alloys, and 10% CaCl2. The control consisted of unreinforced PC specimens. Setting time was determined using a Gillmore apparatus according to standardized methods while compressive strength was measured using a universal testing machine after 21 hours or 60 days of water storage. Data were analyzed by ANOVA, Tukey and Games-Howell tests (α = 5%. All additives significantly decreased both initial and final setting times as compared with the PC-control (p < .05. 30% PMMA and 30% irregular alloy had the lowest values of initial setting time. 30% irregular alloy also produced the lowest values of final setting time while 30% spherical alloy yielded the highest (p < .05. No differences were detected between the compressive strength values of 21 hours and 60 days. While 10% CaCl2, 20% and 30% PMMA produced values significantly lower than the PC-control, 30% spherical alloy significantly improved the compressive strength of the reinforced PC (p < .05. In summary, all additives significantly reduced the setting time and 30% spherical amalgam alloy yielded a significant increase in compressive strength for the tested PC, which might represent an improved composition for PCs to expand their use as endodontic and potentially load bearing materials.

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

    International Nuclear Information System (INIS)

    Highlights: ► Stabilization/solidification of chemical sludge from textile wastewater treatment plants using Portland Pozzolona Cement (PPC) containing fly ash. ► Physical engineering (compressive strength and block density) indicates that sludge has potential to be reused for construction purpose after stabilization/solidification. ► Leaching of heavy metals from stabilized/solidified materials were within stipulated limits. ► There is a modification of microstructural properties of PPC with sludge addition as indicated by XRD and SEM patterns. - Abstract: 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.

  5. Alternativas analíticas para determinação de ferro e titânio em cimento Portland Comparative study of analytical methods for iron and titanium determination in Portland cement

    OpenAIRE

    Jorge de O. Franco Jr.; Maria das Graças A. Korn; Antonio Celso S. Costa; Anibal de Freitas Santos Jr.; Leonardo S. G. Teixeira

    2001-01-01

    In the present work four different analytical methodologies were studied for the determination of iron and titanium in Portland cement. The cement samples were dissolved with hot HCl and HF, being compared Fe and Ti concentrations through four analytical methods: molecular absorption spectrophotometry using the reagents 1,2-hydroxybenzene-3,5-disulfonic acid (Tiron) and the 5-chloro-salicylic acid (CSA), inductively coupled plasma atomic emission spectrometry (ICP-AES) and flame atomic absorp...

  6. Stabilization/solidification (S/S) of mercury-contaminated hazardous wastes using thiol-functionalized zeolite and Portland cement.

    Science.gov (United States)

    Zhang, Xin-Yan; Wang, Qi-Chao; Zhang, Shao-Qing; Sun, Xiao-Jing; Zhang, Zhong-Sheng

    2009-09-15

    Stabilization/solidification (S/S) of mercury-containing solid wastes using thiol-functionalized zeolite and cement was investigated in this study. The thiol-functionalized zeolite (TFZ) used in the study was obtained by grafting the thiol group (-SH) to the natural clinoptilolite zeolites, and the mercury adsorption by TFZ was investigated. TFZ was used to stabilize mercury in solid wastes, and then the stabilized wastes were subjected to cement solidification to test the effectiveness of the whole S/S process. The results show that TFZ has a high level of -SH content (0.562 mmol g(-1)) and the adsorption of mercury by TFZ conform to the Freundlich adsorption isotherm. The mercury adsorption capacity is greatly enhanced upon thiol grafting, the maximum of which is increased from 0.041 mmol Hg g(-1) to 0.445 mmol Hg g(-1). TFZ is found to be effective in stabilizing Hg in the waste surrogate. In the stabilization process, the optimum pH for the stabilization reaction is about 5.0. The optimum TFZ dosage is about 5% and the optimum cement dosage is about 100%. Though Cl(-) and PO(4)(3-) have negative effects on mercury adsorption by TFZ, the Portland cement solidification of TFZ stabilized surrogates containing 1000 mg Hg/kg can successfully pass the TCLP leaching test. It can be concluded that the stabilization/solidification process using TFZ and Portland cement is an effective technology to treat and dispose mercury-containing wastes. PMID:19376646

  7. 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)

  8. 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-compo......-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....

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

    OpenAIRE

    Payá, J.; Garcés, P.; Zornoza, E.

    2008-01-01

    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 ste...

  10. Healing of apical rarefaction of three nonvital open apex anterior teeth using a white portland cement apical plug

    OpenAIRE

    Amitabha Chakraborty; Bibhas Dey; Reema Dhar; Prabir Sardar

    2012-01-01

    The major challenge of performing root canal treatment in an open apex pulp-less tooth is to obtain a good apical seal. MTA has been successfully used to achieve a good apical seal, wherein the root canal obturation can be done immediately. MTA and White Portland Cement has been shown similarity in their physical, chemical and biological properties and has also shown similar outcome when used in animal studies and human trials. In our study, open apex of three non vital upper central incisors...

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

    OpenAIRE

    Telschow, Samira; Jappe Frandsen, Flemming; Theisen, Kirsten; Dam-Johansen, Kim

    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 ...

  12. Electromagnetic interference shielding with Portland cement paste containing carbon materials and processed fly ash

    Directory of Open Access Journals (Sweden)

    Zornoza, E.

    2010-12-01

    Full Text Available The study described in this article explored the effect of adding different types of carbon materials (graphite powder and three types of carbon fibre, fly ash (with 5.6%, 15.9% and 24.3% Fe2O3, and a mix of both on electromagnetic interference (EMI shielding in Portland cement pastes. The parameters studied included the type and aspect ratio of the carbonic material, composite material thickness, the frequency of the incident electromagnetic radiation and the percentage of the magnetic fraction in the fly ash. The findings showed that the polyacrylonitrile-based carbon fibres, which had the highest aspect ratio, provided more effective shielding than any of the other carbon materials studied. Shielding was more effective in thicker specimens and at higher radiation frequencies. Raising the magnetic fraction of the fly ash, in turn, also enhanced paste shielding performance. Finally, adding both carbon fibre and fly ash to the paste resulted in the most effective EMI shielding as a result of the synergies generated.

    En el presente trabajo se investiga la influencia de la adición de diferentes tipos de materiales carbonosos (polvo de grafito y 3 tipos de fibra de carbono, de una ceniza volante con diferentes contenidos de fase magnética (5,6%, 15,9% y 24,3% de Fe2O3 y de una mezcla de ambos, sobre la capacidad de apantallar interferencias electromagnéticas de pastas de cemento Pórtland. Entre los parámetros estudiados se encuentra: el tipo de material carbonoso, la relación de aspecto del material carbonoso, el espesor del material compuesto, la frecuencia de la radiación electromagnética incidente y el porcentaje de fracción magnética en la ceniza volante. Los resultados obtenidos indican que entre los materiales carbonosos estudiados son las fibras de carbono basadas en poliacrilonitrilo con una mayor relación de aspecto las que dan mejores resultados de apantallamiento. Al aumentar

  13. 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...

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

    International Nuclear Information System (INIS)

    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. Crystal chemistry of portland cement hydrates as radioactive waste hosts. Final report, June 15, 1983-June 14, 1984

    International Nuclear Information System (INIS)

    Portland cement hydrates have been used as encapsulant/host phases in radioactive waste management. However, their phase chemistry and stability relationships are poorly defined. Therefore, on occasion, they have not performed as well as expected. As a result, their use has been mainly limited to low-level waste disposal. Since this knowledge gap existed, we had begun to investigate the crystal chemistry of the portland cement hydrates. It was our objective to identify potential hydrate host phases which were not only suitable for isolating radioactive-waste species but also inexpensive, easily processed, low-temperature materials. Initially, we were concentrating upon two areas of interest: the fixation of iodine by the calcium aluminate hydrates and the feasibility of using Stratling's compound as a host phase for cesium and strontium fixation. In both cases, a phase equilibrium study was initiated in order to identify phase relations and consequences of adding the species of interest to the system. An iodine-containing analogue of calcium monosulfoaluminate hydrate (C3A.CaI2.xH2O) was identified as a possible host phase. CsOH was added to formulations in the neighborhood of Stratling's compound, in order to establish phase relations and identify the fixation ability of Stratling's compound and its associated hydrates. 11 figures, 9 tables

  16. Crystal chemistry of portland cement hydrates as radioactive waste hosts. Progress report, June 15, 1983-February 7, 1984

    International Nuclear Information System (INIS)

    Portland cement hydrates have been used as encapsulant/host phases in radioactive waste management. However, their phase chemistry and stability relationships are poorly defined. Therefore, on occassion, they have not performed as well as expected. As a result, their use has been mainly limited to low-level waste disposal. Since this knowledge gap exists, we have begun to investigate the crystal chemistry of the portland cement hydrates. It is our objective to identify potential hydrate host phases which are not only suitable for isolating radioactive-waste species but also inexpensive, easily processed, low-temperature materials. Initially, we have been concentrating upon two areas of interest: The fixation of iodine by the calcium aluminate hydrates and the feasibility of using Straling's compound as a host phase for cesium and strontium fixation. In both cases, a phase equilibrium study has been initiated in order to identify phase relations and consequences of adding the species of interest to the system. An iodine-containing analogue of calcium monosulfoaluminate hydrate (C3A.CaI2.xH2O) has been identified as a possible host phase. CsOH and Sr(OH)2 are being added to formulations in the neighborhood of Stratling's compound, in order to establish phase relations and identify the fixation ability of Stratling's compound and its associated hydrates. 10 figures, 6 tables

  17. 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.

  18. 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

  19. Impact of a 70°C temperature on an ordinary Portland cement paste/claystone interface: An in situ experiment

    OpenAIRE

    Lalan, Philippines; Dauzères, Alexandre; De Windt, Laurent; Bartier, Danièle; Sammaljärvi, Juuso; BARNICHON, Jean-Dominique; Techer, Isabelle; Detilleux, Valéry

    2016-01-01

    Radioactive wastes in future underground disposal sites will induce a temperature increase at the interface between the cementitious materials and the host rock. To understand the evolution of Portland cement in this environment, an in situ specific device was developed in the Underground Research Laboratory in Tournemire (France). OPC cement paste was put into contact with clayey rock under water-saturated conditions at 70°C. The initial temperature increase led to ettringite dissolution and...

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

    International Nuclear Information System (INIS)

    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.%

  1. 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.%.

  2. 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

  3. Influence of addition of calcium oxide on physicochemical properties of Portland cement with zirconium or niobium oxide

    Directory of Open Access Journals (Sweden)

    Mario Tanomaru-Filho

    2015-01-01

    Full Text Available Context: Calcium oxide (CaO may be added to mineral trioxide aggregate (MTA or Portland cement (PC to improve physicochemical and biological properties. Aims: To evaluate the physicochemical properties of PC associated with radiopacifiers and CaO. Materials and Methods: MTA Angelus, PC + 30% zirconium oxide (Zr, or 30% niobium oxide (Nb associated with 10 or 20% of CaO were evaluated. Gilmore needles were used to evaluate initial and final setting time. Compressive strength was evaluated after the periods of 24 hours and 21 days. pH was analyzed after 3, 12, 24 hours, 7, 14, 21 days. Solubility and flow tests were performed based on the ISO 6876. The data obtained were submitted to analysis of variance and Tukey tests (P ≤ 0.05. Results: The associations with 10% CaO showed greater strength that the associations with 20% CaO. The shortest initial setting time was observed for the association PC + Zr + 20% CaO and MTA. All the cements presented alkaline pH. The flow of all cements was similar. The highest solubility was found in the associations with 20% CaO. Conclusion: The addition of CaO to PC favored the alkaline property and the PC + Zr + 20% CaO presented setting time similar to MTA.

  4. 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

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

    Science.gov (United States)

    2012-07-18

    ... that there are 24 cement kilns which combust solid waste. See 76 FR 28322 and Memorandum ``Combustion... reclassifying some cement kilns as commercial and industrial solid waste incinerators (CISWI) and thus could..., the EPA is doing so by removing all kilns classified as commercial and industrial solid...

  6. Influence on the physical-mechanical properties of portland-cement mortar, have admixtures of colophony and tannin

    Directory of Open Access Journals (Sweden)

    Fernández Cánovas, M.

    1989-12-01

    Full Text Available The colophony has been used as an admixture in the Portland cement mortar with the intention to observe its influence on the air content, water absorption, adhesive capacity and mechanical properties. The results obtained have shown that, the colophony acts as air entrainment, reduces the permeability and improves the adhesion between the past and aggregates. Likewise, the addition of tannin and montan wax to the colophony has the efect of reducing the formation of foam and improves the impermeability of the mortar.

    Se ha empleado la colofonia como aditivo en el mortero de cemento portland con el fin de observar su influencia sobre el contenido de aire, absorción de agua, capacidad adhesiva y propiedades mecánicas. Los resultados obtenidos han puesto de manifiesto que la colofonia actúa como aireante, aumenta la impermeabilidad y mejora la adherencia de la pasta al árido. Asimismo, la adición de tanino y cera montana a la colofonia tiene el efecto de reducir la formación de espuma y mejorar también la impermeabilidad del mortero.

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

    International Nuclear Information System (INIS)

    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

  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. 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)

  10. 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.

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

    International Nuclear Information System (INIS)

    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. - 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. 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.

  13. Compatibility of Pretreated Coir Fibres (Cocos nucifera L.) with Portland Cement to Produce Mineral Composites

    OpenAIRE

    Ferraz, Joana M.; Cláudio H. S. Del Menezzi; Mario R. Souza; Okino, Esmeralda Y. A.; Martins, Sabrina A.

    2012-01-01

    The objectives of the present work were to evaluate the chemical compatibility between coir (Cocos nucifera L.) and cement and to study treatment methods to improve this compatibility. In the inhibition test, cement hydration temperature evolution was measured in the absence and presence of untreated and treated coir fibres (cold water, hot water and NaOH), besides the addition of 4% of CaCl2. The chemical characterization of untreated and treated coir fibres was done by determining the conte...

  14. Compatibility of vegetable fibers with Portland cement and its relationship with the physical properties

    OpenAIRE

    Maria L. Marques; Francisco H. M. Luzardo; Fermin G. Velasco; Luis Nieto González; Everton J. da Silva; Wellington G. de Lima

    2016-01-01

    ABSTRACT The use of vegetable fiber residue in cementitious matrices can be a sustainable technological alternative; however, it still has problems related to the chemical compatibility between the cement and the fibers. The present study evaluated the compatibility of vegetable fibers with cement using three methods of calculation and determined certain physical properties of the fibers and the curve of the temporal evolution of temperature for each composite. The surfaces of the composites ...

  15. Electrical properties of Portland cement, with the addition of polypropylene fibres - regarding durability

    OpenAIRE

    Richardson, Alan

    2004-01-01

    This paper makes a comparison between the electrical properties of cement grout with and without monofilament polypropylene fibre additions. The findings show a small, but significant difference between the electrolytic transport properties of cement grout with monofilament polypropylene fibre additions when compared to grout without fibre additions. The grout with fibre additions suggests a reduced probability of water and ion transmission, due to higher measured resistivity, which will resu...

  16. QUARRY DUST FINE POWDER AS SUBSTITUTE FOR ORDINARY PORTLAND CEMENT IN CONCRETE MIX

    OpenAIRE

    KARTINI, K.; HAMIDAH, M. S.; NORHANA, A. R.; NUR HANANI, A. R.

    2014-01-01

    Tremendous efforts have been done in the area of concrete technology to study the utilization of by-products and waste materials which can be used as a partial cement replacement in concrete production as well as identifying the benefits of these alternative materials as cement in concrete. Quarry dust as a by-product from crushing of coarse aggregates during quarrying activities has received considerable attention to enhance the properties of concrete. Thus, this paper reports the research c...

  17. 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.

  18. 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.

  19. Calcium looping spent sorbent as a limestone replacement in the manufacture of portland and calcium sulfoaluminate cements.

    Science.gov (United States)

    Telesca, Antonio; Marroccoli, Milena; Tomasulo, Michele; Valenti, Gian Lorenzo; Dieter, Heiko; Montagnaro, Fabio

    2015-06-01

    The calcium looping (CaL) spent sorbent (i) can be a suitable limestone replacement in the production of both ordinary Portland cement (OPC) and calcium sulfoaluminate (CSA) cement, and (ii) promotes environmental benefits in terms of reduced CO2 emission, increased energy saving and larger utilization of industrial byproducts. A sample of CaL spent sorbent, purged from a 200 kWth pilot facility, was tested as a raw material for the synthesis of two series of OPC and CSA clinkers, obtained from mixes heated in a laboratory electric oven within temperature ranges 1350°-1500 °C and 1200°-1350 °C, respectively. As OPC clinker-generating mixtures, six clay-containing binary blends were investigated, three with limestone (reference mixes) and three with the CaL spent sorbent. All of them showed similar burnability indexes. Moreover, three CSA clinker-generating blends (termed RM, MA and MB) were explored. They included, in the order: (I) limestone, bauxite and gypsum (reference mix); (II) CaL spent sorbent, bauxite and gypsum; (III) CaL spent sorbent plus anodization mud and a mixture of fluidized bed combustion (FBC) fly and bottom ashes. The maximum conversion toward 4CaO·3Al2O3·SO3, the chief CSA clinker component, was the largest for MB and almost the same for RM and MA. PMID:25915150

  20. The removal of phosphate ions from aqueous solution by fly ash, slag, ordinary Portland cement and related blends

    Energy Technology Data Exchange (ETDEWEB)

    N.M. Agyei; C.A. Strydom; J.H. Potgieter [University of Venda, Thohoyandou (South Africa). Department of Chemistry

    2002-12-01

    Phosphate ions have been removed from aqueous solution by fly ash, slag, ordinary Portland cement (OPC) and related cement blends. The rate and efficiency of PO{sub 4}{sup 3-} removal were found to increase in the order: fly ash, slag, OPC, apparently mimicking the order of increasing percent CaO in the adsorbents. Blending OPC with fly ash or slag evidently results in diminished PO{sub 4}{sup 3-} removal efficiency. Better removal was obtained at higher solute concentration, acidic pH and higher temperature. The effect of particle size and the speed of mixing were found not to be significant. A first-order kinetic model was used to obtain values for overall sorption rate constants and intraparticle diffusion constants. The Frumkin isotherm was found to be the appropriate equation for modelling isotherms from the experimental adsorption data, and values have been obtained for the isotherm constants. A 400-mg/l PO{sub 4}{sup 3-} (as P) solution was fed at a steady velocity of 2.0 cm/min through a 2.0-cm fixed-bed column (at pH 9.0 and 25{sup o}C), and breakthrough curves were constructed to obtain estimated adsorption capacity values of 32, 60, 75, 78 and 83 mg PO{sub 4}{sup 3-}/g adsorbent for fly ash, slag, OPC+fly ash, OPC+slag and OPC, respectively.

  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. Fine natural aggregate replacement for sandy residue from itabirite exploitation in Portland cement mortar

    International Nuclear Information System (INIS)

    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)

  3. Hydration kinetics of cements by Time-Domain Nuclear Magnetic Resonance: Application to Portland-cement-derived endodontic pastes

    International Nuclear Information System (INIS)

    Time-Domain Nuclear Magnetic Resonance (TD-NMR) of 1H nuclei is used to monitor the maturation up to 30 days of three different endodontic cement pastes. The “Solid–liquid” separation of the NMR signals and quasi-continuous distributions of relaxation times allow one to follow the formation of chemical compounds and the build-up of the nano- and subnano-structured C–S–H gel. 1H populations, distinguished by their different mobilities, can be identified and assigned to water confined within the pores of the C–S–H gel, to crystallization water and Portlandite, and to hydroxyl groups. Changes of the TD-NMR parameters during hydration are in agreement with the expected effects of the different additives, which, as it is known, can substantially modify the rate of reactions and the properties of cementitious pastes. Endodontic cements are suitable systems to check the ability of this non-destructive technique to give insight into the complex hydration process of real cement pastes.

  4. Hydration mechanisms of ternary Portland cements containing limestone powder and fly ash

    International Nuclear Information System (INIS)

    The effect of minor additions of limestone powder on the properties of fly ash blended cements was investigated in this study using isothermal calorimetry, thermogravimetry (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) techniques, and pore solution analysis. The presence of limestone powder led to the formation of hemi- and monocarbonate and to a stabilisation of ettringite compared to the limestone-free cements, where a part of the ettringite converted to monosulphate. Thus, the presence of 5% of limestone led to an increase of the volume of the hydrates, as visible in the increase in chemical shrinkage, and an increase in compressive strength. This effect was amplified for the fly ash/limestone blended cements due to the additional alumina provided by the fly ash reaction.

  5. Investigation on the Effect of Recycled Asphalt Shingle (RAS in Portland Cement Mortar

    Directory of Open Access Journals (Sweden)

    Jinwoo An

    2016-04-01

    Full Text Available Tear-off roofing shingle, referred to as Reclaimed asphalt shingle (RAS, is the byproduct of construction demolition and it is a major solid waste stream in the U.S. Reuse of this byproduct in road construction sector can contribute to the success of materials sustainability as well as landfill conservation. Ground RAS has similar particle distribution as sand and its major component includes aggregate granules, fibers, and asphalt. To promote the beneficial utilization of RAS, this study evaluates the effect of RAS in cement mortar when used as replacement of sand. In addition, the study investigates how cellulose fibers from RAS behave under high alkaline environment during cement hydration process, which may significantly affect mortar’s strength performance. The laboratory study includes measurements of physical, mechanical, and durability behaviors of cement mortar containing RAS replacing sand up to 30%. It was found that the optimum mixture proportions are 5% and 10% for compressive strength and toughness, respectively.

  6. 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

    OpenAIRE

    Renato Menezes; Clóvis Monteiro Bramante; Roberto Brandão Garcia; Ariadne Letra; Vanessa Graciela Gomes Carvalho; Everdan Carneiro; Sérgio Brunini; Rodrigo Cardoso de Oliveira; Giovana Calichio Canova; Fernanda Gomes de Moraes

    2004-01-01

    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 ...

  7. Mineralogy and microstructure of two Mexican Portland cements for the confinement of radioactive waste

    International Nuclear Information System (INIS)

    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)

  8. 76 FR 28318 - National Emission Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing...

    Science.gov (United States)

    2011-05-17

    ... the status of those fuels. 74 FR at 21138. Although there is a statutory definition of solid waste in... as solid wastes or not) does not appreciably affect cement kilns' HAP emissions. 74 FR at 21138... rules regulating ] Commercial and Industrial Solid Waste Incinerators (CISWI) and proposing a...

  9. Quantitative study on the effect of high-temperature curing at an early age on strength development of concrete. Experiment with mortar using moderate-heat portland cement

    International Nuclear Information System (INIS)

    The effect of high-temperature curing at an early age on the strength development of concrete using moderate-heat portland cement was quantitatively studied. High-temperature curing conditions were set so as to give systematic variations in the temperature-time factors. As a result, the integrated value of curing temperature during the period having a significant effect on the strength development was proposed as a parameter that expressed the degree of high-temperature curing. The effect of high-temperature curing on the strength development of concrete using moderate-heat portland cement could be exactly predicted with the integrated value of curing temperature during the period from 0 to 3 days. (author)

  10. 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.

  11. 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)

  12. 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

  13. Remarks on durability of carbonated and uncarbonated Portland cement under sulphate action. Infrared spectroscopy study

    Directory of Open Access Journals (Sweden)

    Vázquez Moreno, T.

    1973-03-01

    Full Text Available Not availableAl objeto de poder comprobar y comparar los resultados obtenidos sobre una serie de ensayos de prismas pequeños (KOCH y STEINEGGER de 1 X 1 X 6 cm, hechos en colaboración con el "Subcomité de Resistencia Química" del CEMBUREAU, en el I.E.T.c.c. se realizaron tres nuevas series de ensayo con ocho cementos distintos, una de las cuales nos sirvió para estudiar el efecto inhibidor de la carbonatación. También sobre dos de estas series se ha efectuado un estudio de espectroscopia infrarroja, para un mejor esclarecimiento de la durabilidad del cemento portland frente a los sulfatos. En este artículo se resumen los resultados obtenidos, cuyo estudio completo saldrá en una próxima publicación del I.E.T.c.c.

  14. Concentration of electrolyte reserves of the juvenile african catfish clarias gariepinus (burchell, 1822) exposed to sublethal concentrations of portland cement powder in solution

    International Nuclear Information System (INIS)

    The study investigated the effect of sublethal concentrations (39.10, 19.55, 9.87 and 0.00 mg/l) of Portland cement powder in solution on the electrolyte reserves (sodium, potassium, calcium, chloride and inorganic phosphorus) in the serum, liver and kidney of the juvenile African catfish Clarias gariepinus after a 15 day exposure period. The basic function of the determined electrolyte reserves in the body lies in controlling fluid distribution, intra and extra cellular acidobasic equilibrium, maintaining osmotic pressure of body fluid and normal neuro-muscular irritability. The result revealed significant (P0.05) changes in inorganic phosphorus. Sodium, calcium, chloride and inorganic phosphorus and potassium were significantly (P0.05) different in liver and kidney, respectively. Ipso-facto, the effector organs viz: liver and kidney of teleost species - Clarias gariepinus which are primarily responsible for regulating water and ionic movement between external and internal milieu of fishes are susceptible to deleterious effects of Portland cement powder thus sublethal concentration (39.10 mg/l) of Portland cement powder in solution after a 15 day exposure has been most toxic and debilitating to the test fish. (author)

  15. 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.

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

    OpenAIRE

    L. Soriano); Monzó, J.; Borrachero, M. V.; Payá, J.

    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. Nonwoven flax fiber mats and white portland cement composites for building envelopes

    OpenAIRE

    Fernández Carrasco, Lucía; Claramunt Blanes, Josep; Llerena Encalada, Ana; Torrens Martín, David; Ardanuy Raso, Mònica; Zamora i Mestre, Joan-Lluís

    2015-01-01

    Traditionally, architectural materials performance was the key point for developing materials; but nowadays, other criteria’s as sustainability, availability and recyclability are being considered. By the other hand, the addition of fibres as polymers, steel or glass on cement based materials was proved to enhance their performance in terms of ductility, tensile strength, toughness, fatigue strength, impact resistance and energy absorption capacity of matrices. Actually, the use of vegetable ...

  18. Compatibility of vegetable fibers with Portland cement and its relationship with the physical properties

    Directory of Open Access Journals (Sweden)

    Maria L. Marques

    2016-05-01

    Full Text Available ABSTRACT The use of vegetable fiber residue in cementitious matrices can be a sustainable technological alternative; however, it still has problems related to the chemical compatibility between the cement and the fibers. The present study evaluated the compatibility of vegetable fibers with cement using three methods of calculation and determined certain physical properties of the fibers and the curve of the temporal evolution of temperature for each composite. The surfaces of the composites were evaluated through atomic force microscope images and the results showed that the pretreatment of fiber washing significantly favors the compatibility with cement for fibers of eucalyptus, coconut and cocoa, with no influence for water hyacinth fiber. Bivariate correlation analyses showed that the compatibility of the composites is favored by the reduction in the degree of swelling, packing density and specific mass. The results showed that there is a potential use of plant fiber in civil construction and that the physical properties of each type of fiber can offer elements for its selection and pretreatment.

  19. Compatibility of Pretreated Coir Fibres (Cocos nucifera L. with Portland Cement to Produce Mineral Composites

    Directory of Open Access Journals (Sweden)

    Joana M. Ferraz

    2012-01-01

    Full Text Available The objectives of the present work were to evaluate the chemical compatibility between coir (Cocos nucifera L. and cement and to study treatment methods to improve this compatibility. In the inhibition test, cement hydration temperature evolution was measured in the absence and presence of untreated and treated coir fibres (cold water, hot water and NaOH, besides the addition of 4% of CaCl2. The chemical characterization of untreated and treated coir fibres was done by determining the content of extractives, lignin, and holocellulose. The inhibition test graded the untreated fibre as “extreme inhibition,” ratifying the need to provide it a treatment. Treatments done on coir fibres affected positively the compatibility between cement and fibre, reducing the inhibition. The treatments reduced the lignin coir fibres’ and extractives proportion, whose variation was significantly correlated with the reduction of the inhibitory index. These results indicate a possibility for future incorporation of these fibres into the production of mineral composites.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. Role of aluminous component of fly ash on the durability of Portland cement-fly ash pastes in marine environment

    International Nuclear Information System (INIS)

    The durability, of mixtures of two kinds of Spanish fly ashes from coal combustion (ASTM class F) with 0, 15 and 35% replacement of Portland cement by fly ash, in a simulated marine environment (Na2SO4+NaCl solution of equivalent concentration to that of sea water: 0.03 and 0.45 M for sulphate and chloride, respectively), has been studied for a period of 90 days. The resistance of the different mixtures to the attack was evaluated by means of the Koch-Steinegger test. The results showed that all the mixtures were resistant, in spite of the great amount of Al2O3 content of the fly ash. The diffusion of SO42-, Na+ and Cl- ions through the pore solution activated the pozzolanic reactivity of the fly ashes causing the corresponding microstructure changes, which were characterized by X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). As a result, the flexural strength of the mixtures increased, principally for the fly ash of a lower particle size and 35% of addition

  5. 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.

  6. 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.

  7. Effect of Incorporating Nanoporous Metal Phosphate Materials on the Compressive Strength of Portland Cement

    OpenAIRE

    Wellman, Dawn M.; Kent E. Parker; Mattigod, Shas V.; Fryxell, Glen E.

    2008-01-01

    Nanoporous metal phosphate (NP-MPO) materials are being developed for removal of contaminant oxyanions (As(OH)O32−, CrO42−, and TcO4−), and cations (mercury, cadmium, and lead) from water and waste streams. Following sequestration, incorporation of metal laden NP-MPOs as a portion of cement formulation would provide an efficient and low-cost way to immobilize metal laden NP-MPOs in an easily handled waste form suitable for permanent disposal. There are no known investigations...

  8. Sealing of exploratory boreholes in clay reactivity of ordinary portland cement (OPC) grouts and various lithologies from the Harwell research site. Volume 1

    International Nuclear Information System (INIS)

    As part of a research programme on the disposal of radioactive wastes in clay, Ordinary Portland Cement (OPC) has been used in the completion of boreholes on the Harwell Research Site, AERE, Oxfordshire. The purpose of this study was to examine the effect of OPC and the alkaline pore fluids generated during its setting on the various lithological types encountered in the boreholes. To facilitate this, samples of core representing the various rock types were selected and cement-rock composites were prepared from these in the laboratory to simulate the borehole cements. After a curing period of 15 months the cores and associated cement plugs were examined for any signs of reactivity or bonding. The best cement-rock bonding was shown by naturally well-cemented sandstone and limestone lithologies. Although no significant chemical reaction was seen to have occurred between OPC and rock, the OPC appears able to bind onto the rock surface because of the rigidity of the rock surface. Therefore, the best cement rock bonding and seal with OPC may be expected in the limestones of the Great Oolite Group, Inferior Oolite Group and parts of the Corallian beds. Because of the reactivity of OPC towards certain lithologies a better borehole seal in such a sedimentary sequence might be achieved using a bentonite backfill in those parts of the sequence which either react with or bond only weakly to OPC

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

    International Nuclear Information System (INIS)

    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)

  10. 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)

  11. Effect of Incorporating Nanoporous Metal Phosphate Materials on the Compressive Strength of Portland Cement

    Directory of Open Access Journals (Sweden)

    Dawn M. Wellman

    2008-01-01

    Full Text Available Nanoporous metal phosphate (NP-MPO materials are being developed for removal of contaminant oxyanions (As(OHO32−, CrO42−, and TcO4−, and cations (mercury, cadmium, and lead from water and waste streams. Following sequestration, incorporation of metal laden NP-MPOs as a portion of cement formulation would provide an efficient and low-cost way to immobilize metal laden NP-MPOs in an easily handled waste form suitable for permanent disposal. There are no known investigations regarding the incorporation of NP-MPOs in concrete and the effects imparted on the physical and mechanical properties of concrete. Results of this investigation demonstrated that incorporating of NP-MPO materials requires additional water in the concrete formulation which decreases the compressive strength. Thus, incorporation of NP-MPOs in concrete may not serve as an efficient means for long-term disposal.

  12. QUARRY DUST FINE POWDER AS SUBSTITUTE FOR ORDINARY PORTLAND CEMENT IN CONCRETE MIX

    Directory of Open Access Journals (Sweden)

    KARTINI, K.

    2014-04-01

    Full Text Available Tremendous efforts have been done in the area of concrete technology to study the utilization of by-products and waste materials which can be used as a partial cement replacement in concrete production as well as identifying the benefits of these alternative materials as cement in concrete. Quarry dust as a by-product from crushing of coarse aggregates during quarrying activities has received considerable attention to enhance the properties of concrete. Thus, this paper reports the research conducted on the suitability of quarry dust fine powder (QDFP as cementitious material in concrete. The performance in terms of its mechanical and durability index were evaluated on concrete composed of various w/b ratios (0.3, 0.4, 0.5 and 0.6 for replacement level of 3%, 5%, 10% and 15%, and with the inclusion of superplasticizer (Sp to enhance the workability of concrete. The performance was measured at 7, 28, 60, 90 and 120 days of age. The results show that inclusion of QDFP did not enhance the compressive strength of concrete. Rebound number (RN for QDFPSp concrete made of 0.3 and 0.4 w/b ratios achieved good quality, while for those made of 0.5 and 0.6 w/b ratios, it falls under category poor and fair respectively. In terms of durability index performance, the QDFP concrete in higher proportion (up to 15% and with increasing w/b ratio from 0.3 to 0.6 increase the coefficient of permeability, while QDFP concrete can be considered as good concrete since the water absorption recorded below than 10% by mass.

  13. 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.

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

    International Nuclear Information System (INIS)

    Well hydrated cement paste was exposed to MgCl2, CaCl2 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 Mg2 + or Ca2 + compared to Na+. 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

  15. Solidification/Stabilization of High Nitrate and Biodenitrified Heavy Metal Sludges with a Portland Cement/Flyash System

    International Nuclear Information System (INIS)

    Pond 207C at Rocky Flats Environmental Technology Site (RFETS) contains process wastewaters characterized by high levels of nitrates and other salts, heavy metal contamination, and low level alpha activity. The purpose of this research was to investigate the feasibility of treating a high-nitrate waste, contaminated with heavy metals, with a coupled dewateriug and S/S process, as well as to investigate the effects of biodenitrification pretreatment on the S/S process. Pond 207C residuals served as the target waste. A bench-scale treatability study was conducted to demonstrate an S/S process that would minimize final product volume without a significant decrease in contaminant stabilization or loss of desirable physical characteristics. The process formulation recommended as a result a previous S/S treatability study conducted on Pond 207C residuals was used as the baseline formulation for this research. Because the actual waste was unavailable due to difficulties associated with radioactive waste handling and storage, a surrogate waste, of known composition and representative of Pond 207C residuals, was used throughout this research. The contaminants of regulatory concern added to the surrogate were cadmium, chromium, nickel, and silver. Product volume reduction was achieved by dewatering the waste prior to S/S treatment. The surrogate was dewatered by evaporation at 60 to 80 C to total solids contents from 43% to 78% by weight, and treated with Portland cement and fly ash. Two cement to flyash ratios were tested, 2:1 and 1:2, by weight. Contaminant leachability testing was conducted with a 0.5 water to pozzolan (the cement/flyash mixture) ratio and both cement to flyash ratios. Each product was tested for unconfined compressive strength (UCS) and for contaminant leachability by the Toxicity Characteristics Leaching Procedure (TCLP). At the highest solids content achieved by dewatering, 78% solids by weight, the predicted final waste form volume f or Pond 207C

  16. 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.

  17. 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

  18. 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

    OpenAIRE

    Talero, R.

    2008-01-01

    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 sul...

  19. 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)

  20. Effect of FeSO4.7H2O and SnCl2.2H2O added as Chromium (VI) Reducers in Ordinary Portland Cement

    OpenAIRE

    Devesh K. Sharma; Rekha Sharma

    2015-01-01

    The paper compared the effect of additives such as FeSO4.2H2O and SnCl2.2H2O on reduction of water soluble Cr(VI), in ordinary Portland cement (43 grades). The determination of water soluble Cr(VI) from cement samples was precisely conducted by DPC-Spectrophotometer technique. The compressive strength testing of the cement mortar samples was carried out. In addition, hydration properties of cement paste (with and without additives) are reported in this paper. Hydration products were also stud...

  1. Health assessment for Northwestern States Portland Cement Company, Mason City, Cerro Gordo County, Iowa, Region 10. CERCLIS No. IAD980852461. Preliminary report

    Energy Technology Data Exchange (ETDEWEB)

    1989-08-29

    The West Quarry Site/Northwestern States Portland Cement Company is listed by the U.S. Environmental Protection Agency (EPA) on the National Priority Lists (NPL). The site is a 150-acre old abandoned quarry (including kiln dust deposits and the flooded portion which contains contaminated water), located in the western portion of approximately 250 acres of land owned by the Northwestern States Portland Cement Company. Ten monitoring wells were installed at various locations surrounding the site at depths ranging from 14 to 60.6 feet; wells north of the site were located between the pond and Calmus Creek. In July 1987, 1 groundwater sample from each monitoring well, was analyzed for sulfates, total metals, dissolved metals and pH (E E/FIT). Arsenic and lead were quantitatively identified in some of the samples. The site is considered to be of public health concern because of the risk to human health resulting from potential exposure to hazardous substances via soil, surface water, groundwater, and air.

  2. 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.

  3. 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. PMID:20080413

  4. 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.

  5. 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

  6. Effectiveness of the fineness of two South African Portland cements for controlling early-age temperature development in concrete

    OpenAIRE

    P C Graham; Ballim, Y.; J B Kazirukanyo

    2011-01-01

    Temperature gradients due to heat of hydration of cement can cause cracking and present serious structural and serviceability concerns in concrete structures. Engineers use a wide range of strategies to limit the potential for such cracking, mainly by minimising the maximum temperature in the concrete. This paper considers the possibility of using more coarsely ground cement as one of the strategies for reducing the maximum concrete temperature. Two cement clinkers were used to produce cement...

  7. Use of Oscillatory Shear to Study the Effect of Limestone Filler on the Rheology of Early-Age Portland Cement

    OpenAIRE

    Barney, Christopher W; Erk, Kendra

    2013-01-01

    Cement is a material that has been in use since the ancient times and is the most widely manufactured material in industry today. During the production of cement, limestone undergoes a process called calcination which releases CO2. In order to reduce the environmental impact and cost of cement production it has become standard practice to replace a portion of the cement mixture with ground limestone, but this causes a change in the rheological profile of the mixture. This change in rheology a...

  8. 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

  9. Health assessment for Lehigh Portland Cement Company, Mason City, Cerro Gordo County, Iowa, Region 10. CERCLIS No. IAD005288634. Preliminary report

    Energy Technology Data Exchange (ETDEWEB)

    1989-08-29

    The Lehigh Portland Cement Company Site is listed by the U.S. Environmental Protection Agency (EPA) on the National Priorities List (NPL). The site consists of approximately 150 acres and is located in the west side of U.S. Highway 65, in the northern section of Mason City, Cerro Gordo County, Iowa. Seven groundwater samples were analyzed together with 1 field blank (E E/FIT). No significant levels of contaminants were found in the private wells except for sodium (23 mg/1) from one residential well of unknown depth. The contaminants of concern are: arsenic, cadmium, lead, sodium, and sulfates. The site is considered to be of public health concern because of the risk resulting from potential exposure to hazardous substances via soil, surface water, groundwater and air.

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

    International Nuclear Information System (INIS)

    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.

  11. Evaluation of structural behaviour and corrosion resistant of austenitic AISI 304 and duplex AISI 2304 stainless steel reinforcements embedded in ordinary Portland cement mortars

    International Nuclear Information System (INIS)

    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.

  12. Study of the action of phosphate ions contained in the mixing water on the hydration of a Portland cement

    International Nuclear Information System (INIS)

    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)

  13. Análisis cuantitativo de cuarzo-alfa en mezclas de cemento portland anhidro y calcita sintética por difracción de rayos X con equipo Philips PW-1700

    OpenAIRE

    Sagrera-Moreno, J. L.

    1985-01-01

    In this article there are explained the necessary steps to make up a quantitative analysis of alpha-quartz applying the technique of rays X diffraction, in artificial mixtures of anhydrous portland cement and synthetic calcite, which contents are known.

    En el presente artículo se explican los pasos necesarios para realizar un análisis cuantitativo de cuarzo-alfa aplicando la técnica de difracción de rayos X en mezclas artificiales de cemento portland anhidro y calcita sinté...

  14. Análisis cuantitativo de cuarzo-alfa en mezclas de cemento portland anhidro y calcita sintética por difracción de rayos X con equipo Philips PW-1700

    Directory of Open Access Journals (Sweden)

    Sagrera-Moreno, J. L.

    1985-09-01

    Full Text Available In this article there are explained the necessary steps to make up a quantitative analysis of alpha-quartz applying the technique of rays X diffraction, in artificial mixtures of anhydrous portland cement and synthetic calcite, which contents are known.

    En el presente artículo se explican los pasos necesarios para realizar un análisis cuantitativo de cuarzo-alfa aplicando la técnica de difracción de rayos X en mezclas artificiales de cemento portland anhidro y calcita sintética, cuyos contenidos son conocidos.

  15. Health assessment for Northwestern States Portland Cement Company, Mason City, Cerro Gordo County, Iowa, Region 7. CERCLIS No. IAD980852461. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1991-12-27

    The Northwestern States Portland Cement Company (NWSPCC) NPL site is situated in the northern section of Mason City, Cerro Gordo County, Iowa. The major concern at the site is contaminated surface water and ground water as a result of contact with waste cement kiln dust in the West Quarry. On-site surface water and ground water are contaminated with lead, sodium, sulfates, and reflects high pH. The waste kiln dust is in contact with both the surficial and Devonian aquifers on site; hence, there is a potential for contamination of the Devonian aquifer off-site. Potential exposure pathways of concern include ingestion of contaminated ground water; accidental ingestion and dermal contact with contaminated surface water, and accidental ingestion and dermal contact with contaminated soils and sediment; and inhalation of entrained dust. Under current conditions the NWSPCC NPL site poses no apparent public health hazard. However, potential risk to human health resulting from possible exposure to on-site and off-site hazardous substances exists in the future if the site is not remediated. The site is currently under remediation to mitigate the potential risk.

  16. 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

  17. 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

  18. 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.

  19. The strength retrogression of special class Portland oilwell cement Regressão de resistência de um cimento Portland classe especial para cimentação de poço de petróleo

    Directory of Open Access Journals (Sweden)

    U. T. Bezerra

    2011-06-01

    Full Text Available Temperatures in excess of 110 ºC result in phase transformations of cement, significantly decreasing its compressive strength. This effect is referred to as strength retrogression. It is frequently observed in cement sheaths of heavy oil wells submitted to steam injection. The present study evaluated the mechanical behavior of Special Class Portland Oilwell Cement (SCPOC slurries containing silica flour to prevent retrogression. A factorial statistical planning was used to assess the effect of the main variables on the mechanical behavior of cement slurries, i.e., mechanical testing temperature (30, 100, 120, 180 and 230 ºC; contents of silica flour replacing cement (0-18 and 36% and curing time for rupture (12 h and 7 days. The results revealed that slurries containing 18% of silica flour tested at 230 ºC depicted an increase in compressive strength up to 30% after curing for 12 h and 10% after curing for 7 days, indicating retrogression. On the other hand, testing slurries containing silica flour at temperatures up to 180 ºC revealed strength increase of just 10%, suggesting the mechanical stability of the SCPOC, which prevents retrogression. Such behavior was probably related to the relatively low content of C3A and low specific area of the material. Therefore, strength retrogression at typical bottom hole temperatures of up to 180 ºC can be controlled by small additions of silica flour, economically contributing to the use of SCPOC cementing.Temperaturas superiores a 110 ºC provocam mudanças de fase nos cimentos, reduzindo de forma significativa sua resistência à compressão. Isto é observado com frequência em bainhas de cimento em poços de petróleo pesado, que são submetidos a injeção de vapor. O presente estudo avaliou o comportamento mecânico de pastas para cimentação preparadas com um cimento portland Classe especial contendo silica flour para prevenção da regressão de resistência. Um planejamento fatorial foi

  20. 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.

  1. 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.

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

    International Nuclear Information System (INIS)

    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

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

    OpenAIRE

    Cruz González, José Mª; Fita Fernández, Inmaculada Concepción; Soriano Martinez, Lourdes; Paya Bernabeu, Jorge Juan; Borrachero Rosado, María Victoria

    2013-01-01

    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 ...

  4. 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.

  5. 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

    International Nuclear Information System (INIS)

    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

  6. 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.

  7. Improved Photodegradation of Organic Contaminants Using Nano-TiO2 and TiO2 -SiO2 Deposited on Portland Cement Concrete Blocks.

    Science.gov (United States)

    Jafari, Hoda; Afshar, Shahrara

    2016-01-01

    The photocatalytic activity of TiO2 nanoparticles (nano-TiO2 ) and its hybrid with SiO2 (nano-TiO2 -SiO2 ) for degradation of some organic dyes on cementitious materials was studied in this work. Nanohybrid photocatalysts were prepared using an inorganic sol-gel precursor and then characterized using XRD, SEM and UV-Vis. The grain sizes were estimated by Scherrer's equation to be around 10 nm. Then, a thin layer was applied to Portland cement concrete (PCC) blocks by dipping them into nano-TiO2 and nano-TiO2 -SiO2 solution. The efficiency of coated PCC blocks for the photocatalytic decomposition of two dyes, Malachite Green oxalate (MG) and Methylene Blue (MB), was examined under UV and visible irradiation and then monitored by the chemical oxygen demand tests. The results showed that more than 80% and 92% of MG and MB were decomposed under UV-Vis irradiation using blocks coated with nano-TiO2 -SiO2 . TiO2 /PCC and TiO2 -SiO2 /PCC blocks showed a significant ability to oxidize dyes under visible and UV lights and TiO2 -SiO2 /PCC blocks require less time for dye degradation. Based on these results, coated blocks have increased photocatalytic activity which can make them commercially accessible photocatalysts. PMID:26648581

  8. 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.

  9. Deterioration study of a material for encapsulation of radioactive wastes, the Portland cement, by heterotrophic microorganisms isolated from natural media

    International Nuclear Information System (INIS)

    Soils and geologic formations selected for storage of radioactive waste storage contain microflora (nitrifying and sulfoxidizing bacteria, heterotrophic microorganisms) that can corrode cement through acidic metabolism products. Nutriments required for their development are also found in these biotopes. Corrosine effects of organic acids produced by heterotrophic microorganisms are: mass decrease, leaching (especially Ca), dissolution of portlandite crystals Ca (OH)2, increase of porosity and decrease of flexural strength. Excretion of corrosive organic acids by bacteria is promoted by high temperature and basic pH. Acidification by fungi requires also a high temperature but an acidic pH

  10. Multi-criteria analysis of the mechanism of degradation of Portland cement based mortars exposed to external sulphate attack

    International Nuclear Information System (INIS)

    This work aims to contribute to the design of durable concrete structures exposed to external sulphate attacks (ESA). Following a preliminary study aimed at designing a representative test, the present paper suggests a study on the effect of the water-to-cement (w/c) ratio and the cement composition in order to understand the degradation mechanisms. Length and mass measurements were registered continuously, leached calcium and hydroxide ions were also quantified. In parallel, scanning electron microscopy observations as well as X-ray microtomography were realised at different times to identify the formed products and the crack morphology. Test results provide information on the basic aspects of the degradation mechanism, such as the main role of leaching and diffusion in the sulphate attack process. The mortar composition with a low w/c ratio leads to a better resistance to sulphate attack because the microstructure is less permeable. Reducing the C3A content results in a macro-cracking decrease but it does not prevent expansion, which suggests the contribution of other expansive products, such as gypsum, in damage due to ESA. The observation of the cracks network in the microstructure helps to understand the micro-mechanisms of the degradation process.

  11. 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

  12. A correlation between Bogue's equations and Taylor's procedure for the evaluation of crystalline phases in special class Portland oilwell cement clinker Correlação entre as equações de Bogue e o procedimento de Taylor na avaliação das fases cristalinas de um cimento Portland especial para cimentação de poços de petróleo

    OpenAIRE

    U. T. Bezerra; A. E. Martinelli; D. M. A. Melo; M. A. F. Melo; F. M. Lima

    2011-01-01

    The crystalline composition of Portland cement clinker is commonly established by Bogue's equations, which are based on a series of assumptions that seldom apply to oilwell cements. This is probably due to the presence of additional oxides and phase reconversion upon cooling of the clinker from the calcination temperature. Important differences are therefore observed between the numerical values yielded by the mathematical equations and image analysis quantification. In this study, the concen...

  13. Effect of FeSO4.7H2O and SnCl2.2H2O added as Chromium (VI Reducers in Ordinary Portland Cement

    Directory of Open Access Journals (Sweden)

    Devesh K. Sharma

    2015-03-01

    Full Text Available The paper compared the effect of additives such as FeSO4.2H2O and SnCl2.2H2O on reduction of water soluble Cr(VI, in ordinary Portland cement (43 grades. The determination of water soluble Cr(VI from cement samples was precisely conducted by DPC-Spectrophotometer technique. The compressive strength testing of the cement mortar samples was carried out. In addition, hydration properties of cement paste (with and without additives are reported in this paper. Hydration products were also studied in detail by TGA, SEM and XRD. Tin chloride was found to be the most efficient additive for reducing Cr(VI in cement. XRD confirmed two phases such as monocarbonate and Friedel’s salt (at 2θ = 11.5 were formed during cement hydration in the presence of tin chloride but not confirmed the presence of calcium hydroxo-stannate. These studies showed significant retardation in early days hydration.

  14. 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

  15. 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

  16. A comparative analysis of the wear characteristics of glazes generated on the ordinary Portland cement surface of concrete by means of CO2 and high power diode laser radiation

    OpenAIRE

    Lawrence, Jonathan

    2004-01-01

    The wear characteristics of a glaze generated on the ordinary Portland cement (OPC) surface of concrete using a 2 kW high power diode laser (HPDL) and a 3 kW CO2 laser have been determined. Within both normal and corrosive environmental conditions, the wear rate of the CO2 and HPDL generated glazes were consistently higher than the untreated OPC surface of concrete. Life assessment testing revealed that surface glazing of the OPC with both the CO2 and the HPDL effected an increase in wear lif...

  17. A new geopolymeric binder from hydrated-carbonated cement

    OpenAIRE

    Paya Bernabeu, Jorge Juan; Borrachero Rosado, María Victoria; Monzó Balbuena, José Mª; Soriano Martinez, Lourdes; Mitsuuchi Tashima, Mauro

    2012-01-01

    This paper evaluates the use of hydrated Portland cement as the raw material in the production of geopolymers. The silicon and aluminium oxides needed for the geopolymerization process were produced by the carbonation of hydrated Portland cement, which transforms CSH and CAH (Portland cement hydrates) into silica and alumina gels. Hydrated-carbonated Portland cement was alkali activated with a NaOH/waterglass solution. Pastes and mortars were prepared, and micro-structural and mechanical prop...

  18. 复合硅酸盐水泥的生命周期评价%Life cycle assessment of composite portland cement

    Institute of Scientific and Technical Information of China (English)

    徐小宁; 陈郁; 张树深; 张芸; 宋国宝

    2013-01-01

    Composite Portland Cement (CPC) mixed with industrial residues has a destructive impact on ecological environment.This paper presents a life cycle assessment (LCA) of CPC using Gabi 4.4 and evaluates the environmental impact potentials during the production of cement.The parameters including Abiotic Depletion (A DP),Acidification Potential (A P),Eutrophication Potential (EP),Global Warming Potential (GWP),Human Toxicity Potential (HTP) and Photochemical Ozone Creation Potential (POCP) are analyzed and compared.The results show that,compared to other environmental impact potentials,the GWP potential is the most influenced factor,with the contribution proportion of 71%.Regarding the extent of environmental impacts,these parameters can be ordered as:GWP,AP,ADP,HTP,EP and POCP.Compared to other stages,calcination stage exerts the most destructive influence on the environment,with the contribution proportion of 68%.Regarding the extent of environmental impacts,the stages can be ordered as:calcination stage,grinding stage,transport,raw material preparation and raw material mining.The highest GWP,ADP and AP values are generated during calcination stage,the highest HTP and POCP values during grinding stage and the highest EP value during transport stage.This paper discusses the LCA of CPC to provide data for LCA of cement in China and to promote the sustainable development pattern for cement and construction industry.%掺加大量工业废渣的复合硅酸盐水泥其生产过程对生态环境有重要的影响.因此,本文利用Gabi 4.4软件,对复合硅酸盐水泥进行生命周期评价,比较分析生命周期各生产阶段中的非生物资源耗竭、全球变暖潜值、酸化效应、富营养化、人体毒性及光化学臭氧生成潜力等主要环境影响类型.结果表明,全球变暖潜值是复合硅酸盐水泥环境影响的主要类型,占总环境影响值的71%.环境影响大小顺序依次为全球变暖潜值、酸化效应、非生

  19. 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

  20. Chemical and mineralogical characterization of two commercial cements and its evolution in function of time

    International Nuclear Information System (INIS)

    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)

  1. 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.

  2. 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

    OpenAIRE

    Panzera, T. H.; A. L. R. Sabariz; K. Strecker; Borges, P. H. R.; D. C. L. Vasconcelos; W. L. Wasconcelos

    2010-01-01

    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 aument...

  3. 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

  4. 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.

  5. Effects of Sulfate during CO2 Attack on Portland Cement and Their Impacts on Mechanical Properties under Geologic CO2 Sequestration Conditions.

    Science.gov (United States)

    Li, Qingyun; Lim, Yun Mook; Jun, Young-Shin

    2015-06-01

    To investigate the effects of sulfate on CO2 attack on wellbore cement (i.e., chemical and mechanical alterations) during geologic CO2 sequestration (GCS), we reacted cement samples in brine with 0.05 M sulfate and 0.4 M NaCl at 95 °C under 100 bar of either N2 or supercritical CO2. The results were compared to those obtained from systems without additional sulfate at the same temperature, pressure, salinity, and initial brine pHs. After 10 reaction days, chemical analyses using scanning electron microscopy with a backscattered electron detector (SEM-BSE) and inductively coupled plasma optical emission spectrometry (ICP-OES) showed that the CO2 attack in the presence of additional sulfate was much less severe than that in the system without additional sulfate. The results from three-point bending tests also indicated that sulfate significantly mitigated the deterioration of the cement's strength and elastic modulus. In all our systems, typical sulfate attacks on cement via formation of ettringite were not observed. The protective effects of sulfate on cement against CO2 attack resulted from sulfate adsorption, coating of CaSO4 on the CaCO3 grains in the carbonated layer, or both, which inhibited dissolution of CaCO3. Findings from this study provide new, important information for understanding the integrity of wellbores at GCS sites and thus promote safer GCS operations. PMID:25938805

  6. 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.

  7. 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)

  8. 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

  9. 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.

  10. 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

  11. Composite cements containing natural pozzolan and granulated blast furnace slag

    OpenAIRE

    Irassar, E. F.; Rahhal, V.F.; Donza, H. A.; Menéndez, G.; Bonavetti, V. L.

    2006-01-01

    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 p...

  12. Simultaneous study of mechanical property development and early hydration chemistry in Portland cement slurries using X-ray diffraction and ultrasound reflection

    International Nuclear Information System (INIS)

    A sample cell for the simultaneous measurement of synchrotron X-ray powder diffraction and ultrasound shear-wave reflection data from cement slurries is described. White cement slurries at 25 and 50 °C with 0–3% bwoc CaCl2 were studied to illustrate the potential of the apparatus. The decrease in reflected S-wave amplitude, in dB, showed a linear correlation with C3S hydration. CaCl2 retarded the development of G′ and G″ relative to the extent of C3S hydration. At short times, there was a correlation between the time evolution of both G′ and G″, and the amount of precipitated CH seen by diffraction, which was almost independent of CaCl2 concentration and temperature. CaCl2 addition resulted in a decrease in the amount of CH visible to X-rays, relative the degree of C3S hydration. This may indicate a change in C–S–H gel C:S ratio or the presence of nanoscale CH that could not be seen by diffraction.

  13. Strength and durability of concrete: Effects of cement paste-aggregate interfaces. Part 2: Significance of transition zones on physical and mechanical properties of portland cement mortar; Final report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, T.F.F.; Cohen, M.D.; Chen, W.F.; Zhang, Y.

    1998-08-01

    The research was based on a two-part basic research investigation studying the effects of cement paste-aggregate interfaces (or interfacial transition zones-ITZ) on strength and durability of concrete. Part 1 dealt with the theoretical study and Part 2 dealt with the experimental.

  14. 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

    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......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...

  15. 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)

  16. A new method for designing floor slabs on grade due to the difficulty of applying simplified design methods, amongst them being the Portland Cement Association (PCA and Wire Reinforcement Institute (WRI methods

    Directory of Open Access Journals (Sweden)

    Hugo Ernesto Camero Sanabrial

    2010-04-01

    Full Text Available This article presents a methodology for designing slabs on grade for industrial floors where there is an eccentricity between the slab centroid and the gravity centre loads of the loaded axle of forklift trucks travelling over the floor. An example was used for analysing how Portland Cement Association (PCA and the Wire Reinforcement Institute (WRI methods are inadequate for designing floors sublected to this condition. The new proposal for designing slabs on grade for industrial floors has been called the Camero method. An example of an industrial floor designed to be capable of sustaining an infinite number of load applications (or 50-year life was compared to the results of the Camero method and PCA and WRI’s simplified methods. Industrial floors should be capable of sustaining an infinite number of load applications (50-year life if designed with the Camero method; on the other hand, if designed using PCA and WRI methods they will only last one year (in this example the number of axle load applications in a 1-year period was equal to the number of allowable repetitions because they will not be able to sustain an infinite number of load applications. It was concluded that designing plain concrete slabs (without reinforcement on grade according to PCA and the WRI methods leads to slab fatigue, even though extreme fibre stress should not exceed 50 percent (50% of static modulus of concrete rupture and slabs should sustain an infinite number of load repetitions (infinite amount of forklift truck traffic were considered parameters in their design.

  17. Durability of ultra-high performance concretes: role of the cement matrix

    International Nuclear Information System (INIS)

    The Reactive Powder Concretes (RPC), composed of Portland cement, silica fume, crushed quartz, fine sand and steel fibers, exhibit a very dense microstructure which limits the penetration of aggressive agents. They appear suitable for the storage of nuclear waste. This study aimed to determine experimentally the evolution of the RPC microstructure during a leaching attack by pure water, and to supply data required for the RPC long-term prediction of durability under these severe conditions. The steel fibers and mineral inclusions (sand and quartz) were considered as inert materials in the degradation process. Thus RPC matrices, and also a pure cement paste, and a cement and silica fume paste, were studied. The materials were characterised before and after a leaching test: microstructure by means of scanning electron microscopy, porosity, chemical and mineralogical composition, and diffusivity. A superficial degradation proceeds along a straight leaching front related to the dissolution of the remaining anhydrous cement silicates (C3S and C2S). The leaching of mineral species is controlled by the ionic diffusions from the material towards the aggressive solution. The degradation kinetics is proportional to the square root of time. As long as a sound core remains, the global behaviour of the partly degraded material is determined by the properties of the sound core. Two models related to the matrix transformation were used: DIFFU-Ca which characterised the leaching of calcium, and the 3D computer simulation of Portland cement hydration and microstructure development, from BENTZ and GARBOCZI. The digital results show a good agreement with the experimental values. This validates the hydration rates predicted with BENTZ and GARBOCZI and the phenomenology implemented in DIFFU-Ca. At the end of the study, it could be said that RPC appears as a suitable candidate for nuclear waste storage. The foreseen degradation depth after a 300 years leaching is about 1.4 cm in our

  18. 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.

  19. 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.

  20. 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.

  1. Characteristics and propierties of oil-well cements additioned with blast furnace slag

    OpenAIRE

    Sánchez, R.; Palacios, M.; Puertas, F.

    2011-01-01

    The present paper addresses the alkali activation of Portland cements containing blast furnace slag (20 and 30% of the cement by 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 activating solution partially inhibited the dissolution of the silicate phases in the Portland cement, retarding cement hydration and reducing the precipitation of reaction products. D...

  2. Manufacture and properties of fluoride cement

    Science.gov (United States)

    Malata-Chirwa, Charles David

    This research work aimed at characterising composition, hydration and physical properties of fluoride cement, by studying samples of the cement obtained from Malawi, and comparing them to ordinary Portland cement. By confirming the suitable characteristics of fluoride cement through this work, the results of the research work provide a good basis for the wider adoption of fluoride cement as an alternative to ordinary Portland cement, especially in developing economies. Numerous accounts have been cited regarding the production and use of fluoride cement. Since there have not been conclusive agreement as to its properties, this study was limited to the theories of successful incorporation of fluoride compounds in the manufacture of fluoride cement. Hence, the properties and characteristics reported in this study relate to the cement currently manufactured in Malawi, and, on a comparative basis only, to that manufactured in other parts of the world. Samples of the fluoride cement used in the study were obtained by synthetic manufacture of the cement using common raw materials for the manufacture of fluoride cement that is limestone, silica sand, and fluorspar. These samples were subjected to several comparative tests used to characterise cements including examination under x-ray diffractometer, scanning electron microscopy and tests for setting time and compressive strength. Under similar laboratory conditions, it was possible to prove that fluoride cement hardens more rapidly than ordinary Portland cement. Also observed during the experimental work is that fluoride cement develops higher compressive strengths than ordinary Portland cement. The hardening and setting times are significantly different between the two cements. Also the nature of the hydration products, that is the microstructural development is significantly different in the two cements. The differences brought about between the two cements are because of the presence of fluorine during the clinkering

  3. HYDRATING CHARACTERISTICS OF MODIFIED PORTLAND WITH Ba-BEARING SULPHOALUMINATE MINERALS

    OpenAIRE

    Chenchen Gong; Jibao Xin; Shoude Wang; Lingchao Lu

    2016-01-01

    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 ...

  4. 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.

  5. 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.

  6. Advances in understanding hydration of Portland cement

    International Nuclear Information System (INIS)

    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 C3A 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

  7. 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

  8. Improvement of Cement Strength by Induction Method

    Institute of Scientific and Technical Information of China (English)

    YANG Li-yuan; LIN Zong-shou

    2004-01-01

    The induction method of improving the strength of Portland cement by adding fine slag powder,high aluminate component and hydrated paste was investigated through determining the physical properties,hydration heat and pore size distribution,and its mechanism was discussed.The experimental results reveal that a certain content of high aluminate component,fine slag powder and hydrated paste can improve remarkably the strength of Portland cement.

  9. 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.

  10. 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.

  11. 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)

  12. The incorporation of low and medium level radioactive wastes (solids and liquids) in cement

    International Nuclear Information System (INIS)

    Experimentation has shown that high temperatures generated during the setting of ordinary Portland cement/simulant waste mixes can be significantly reduced by the use of a blend of ground granulated blast furnace slag and ordinary Portland cement. Trials on simulated waste showed that blended cement gave improved stability and a reduction in leach rates, and confirmed that the cement-based process can be used for the immobilisation of most types of low and medium level waste. (U.K.)

  13. 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)

  14. 21 CFR 168.110 - Dextrose anhydrous.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Dextrose anhydrous. 168.110 Section 168.110 Food... Table Sirups § 168.110 Dextrose anhydrous. (a) Dextrose anhydrous is purified and crystallized D-glucose... solids content is not less than 98.0 percent m/m. (b) The name of the food is “Dextrose anhydrous”...

  15. 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

  16. 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...

  17. 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...

  18. 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

  19. 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.

  20. Laboratory studies on the longevity of cement grouts

    International Nuclear Information System (INIS)

    This paper describes laboratory studies of the longevity of cement-based grouts being carried out as part of the International Stripa Project Phase III. The longevity properties determined for a reference grout (90% Sulphate Resistant Portland Cement, 10% silica fume, 0.4< water/cement<0.6 and superplasticizer) are compared with those of a slag cement grout. Laboratory tests have been carried out to determine the following: the mechanistic function of superplasticizer in fresh cement pastes; the leachability of the sorbed superplasticizer and its location in the structure of hardened cement paste; and the general leaching properties of selected cement-based grouts

  1. Improving the CO2 performance of cement, part III : The relevance of industrial symbiosis and how to measure its impact

    OpenAIRE

    Ammenberg, Jonas; Baas, Leo; Eklund, Mats; Feiz, Roozbeh; Helgstrand, Anton; Marshall, Richard

    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...

  2. Pore Distribution and Water Uptake in a Cenosphere–Cement

    OpenAIRE

    Baroniņš, J; Sētiņa, J; Šahmenko, G; Lagzdiņa, S; Šiškins, A

    2015-01-01

    Alumina silicate cenospheres (CS) is a significant waste material from power plants that use a coal. Use CS as Portland cement replacement material gives opportunity to control physical and mechanical properties and makes a product lighter and more cost-effective. In the frame of this study, Portland cement paste samples were produced by adding CS in the concentration range from 0 to 40 volume %. Water uptake of hardened samples was checked and pore ...

  3. 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

    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...... seven days, dilatometers were manually recorded during at least 56 days. The dispersion model was applied to fit chemical shrinkage results and to estimate the maximum (or ultimate) value for calculation of degree of hydration. Except for a pure Portland cement best fits were obtained by the general...

  4. The aggressiveness of pig slurry to cement mortars

    OpenAIRE

    Massana Guitart, Jordi; Guerrero Bustos, Ana; Antón Fuentes, Rebeca; Garcimartin Molina, Miguel Angel; Sanchez Espinosa, Elvira

    2013-01-01

    The aim was to measure the behaviour of various mortars employed in livestock media in central Spain and to analyse the aggressiveness of pig slurry to cement blended with fly ash mortars. To achieve this, mortar specimens were immersed in ponds storing pig slurry. Mortar specimens, of 40 ? 40 ? 160 mm, were made from four types of cement commonly used and recommended for rural areas. The types were a sulphate-resistant Portland cement and three cements blended in different proportions with ...

  5. 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

    OpenAIRE

    M. S. Picanço; R. S. Angélica; M. S. Barata

    2011-01-01

    As zeolitas possuem atividade pozolânica normalmente sem a necessidade de ativação térmica, por isto têm sido empregadas na produção de cimento e concreto hidráulicos desde a época do império romano. Hoje em dia são utilizadas na fabricação do cimento Portland através da substituição do clinquer em percentuais que variam entre 5 e 20%, dependendo da reatividade e da finura da zeólita. Em razão disto, são muito importantes do ponto de vista econômico e ambiental, principalmente quando não nece...

  6. The incorporation of low and medium level radioactive wastes (solids and liquids) in cement

    International Nuclear Information System (INIS)

    The use of cement has been investigated for the immobilization of liquid and solid low and medium level radioactive waste. 220 litre mixing trials have demonstrated that the high temperatures generated during the setting of ordinary Portland cement/simulant waste mixes can be significantly reduced by the use of a blend of ground granulated blast furnace slag and ordinary Portland cement. Laboratory and 220 litre trials using simulant wastes showed that the blended cement gave an improvement in properties of the cemented waste product, e.g. stability and reduction in leach rates compared with ordinary Portland cement formulations. A range of 220 litre scale mixing systems for the incorporation of liquid and solid wastes in cement was investigated. The work has confirmed that cement-based processes can be used for the immobilization of most types of low and medium level waste

  7. Cements in Radioactive Waste Disposal

    International Nuclear Information System (INIS)

    The use of cement and concrete to immobilise radioactive waste is complicated by the wide- ranging nature of inorganic cementing agents available as well as the range of service environments in which cement is used and the different functions expected of cement. For example, Portland cement based concretes are widely used as structural materials for construction of vaults and tunnels. These constructions may experience a long pre-closure performance lifetime during which they are required to protect against collapse and ingress of water: strength and impermeability are key desirable characteristics. On the other hand, cement and concrete may be used to form backfills, ranging in permeability. Permeable formulations allow gas readily to escape, while impermeable barriers retard radionuclide transport and reduce access of ground water to the waste. A key feature of cements is that, while fresh, they pass through a fluid phase and can be formed into any shape desired or used to infiltrate other materials thereby enclosing them into a sealed matrix. Thereafter, setting and hardening is automatic and irreversible. Where concrete is used to form structural elements, it is also natural to use cement in other applications as it minimises potential for materials incompatibility. Thus cement- mainly Portland cement- has been widely used as an encapsulant for storage, transport and as a radiation shield for active wastes. Also, to form and stabilise structures such as vaults and silos. Relative to other potential matrices, cement also has a chemical immobilisation potential, reacting with and binding with many radionuclides. The chemical potential of cements is essentially sacrificial, thus limiting their performance lifetime. However performance may also be required in the civil engineering sense, where strength is important, so many factors, including a geochemical description of service conditions, may require to be assessed in order to predict performance lifetime. The

  8. 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

  9. 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.

  10. 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.

  11. Accelerated tests of hardened cement pastes alteration by organic acids: analysis of the pH effect

    International Nuclear Information System (INIS)

    Effluents, such as liquid manure and silage effluents, stored in silos often made of concrete, contain organic acids that are chemically very aggressive for the cement-based matrix. The pH of liquid manure is comprised between 6 and 8, and the pH of silage effluent is about 4. There has already been much research done on manure's effect on concrete using aggressive solutions with a pH of or inferior to 4, in order to accelerate alteration kinetics. These studies aimed at simulating liquid manure and silage effluent, equally. The goal of this article is to validate the use of solutions with a pH of 4 to implement accelerated studies on alterations occurring to structures exposed to the acidic part of liquid manure. In this study, the alteration mechanisms of the cement-based matrix produced by two solutions of organic acids with pH of 4 and 6 were compared. At the end of the experiment, carried out on ordinary Portland cement and slag cement pastes, the kinetics of alteration of the cement pastes immersed in the solution with a pH of 4 was ninefold higher than in the solution with a pH of 6. The chemical and mineralogical modifications of the paste were analyzed by electron microprobe, XRD and BSE mode observations. It was shown that the alteration mechanisms of the paste are sensibly identical for both solutions: almost complete decalcification, the disappearance of the crystallized or amorphous hydrated phases and the probable formation of a silica gel containing aluminum and iron, mainly. The differences in alteration mechanisms between the two solutions are minor and mainly concern the stability of the anhydrous phases: C4AF and slag grains

  12. Performance of Cement Containing Laterite as Supplementary Cementing Material

    Directory of Open Access Journals (Sweden)

    Abbas Bukhari, Z. S.

    2013-03-01

    Full Text Available The utilization of different industrial waste, by-products or other materials such as ground granulated blast furnace slag, silica fume, fly ash, limestone, and kiln dust, etc. as supplemen- tary cementing materials has received considerable attention in recent years. A study has been conducted to look into the performance of laterite as Supplementary Cementing Materials (SCM. The study focuses on compressive strength performance of blended cement containing different percentage of laterite. The cement is replaced accordingly with percentage of 2 %, 5 %, 7 % and 10 % by weight. In addition, the effect of use of three chemically different laterites have been studied on physical performance of cement as in setting time, Le-Chatlier expansion, loss on ignition, insoluble residue, free lime and specifically compressive strength of cement cubes tested at the age of 3, 7, and 28 days. The results show that the strength of cement blended with laterite as SCM is enhanced. Key words: Portland cement, supplementary cementing materials (SCM, laterite, compressive strength KUI – 6/2013 Received January 4, 2012 Accepted February 11, 2013

  13. Estudo para o aproveitamento de resíduos pétreos de marmorarias, como agregados para concreto de cimento Portland

    OpenAIRE

    Fábio Conrado de Queiroz; Maria Heloisa Barros de Oliveira Frascá

    2008-01-01

    In this paper, it is presented a study for the utilization of marble shops waste (stone by-products) as aggregate of Portland cement concrete. First, the material were separated and classified by lithologic type. After that, they were mixed in a crusher, producing the required aggregates. Several tests for technological characterization of the material were done, intending to evaluate the use of the material as aggregate. Some simulations of Portland cement concrete dosage were done with vari...

  14. Analyses of microstructural properties of VA/VeoVA copolymer modified cement pastes

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo M. Gomes

    2005-07-01

    Full Text Available 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 distinct polymer contents and water/cement ratios were employed. In addition, analyses of FT-IR and MIP on Portland cement pastes modified by the copolymer were employed. The results showed that the addition of polymer interferes significantly in the reduction of Portlandite formation and increases the porosity of the matrices. A possible chemical interaction between the copolymer and hydrated products of Portland cement was also observed.

  15. Rheological Properties of Cemented Tailing Backfill and the Construction of a Prediction Model

    OpenAIRE

    Liu Lang; KI-IL Song; Dezheng Lao; Tae-Hyuk Kwon

    2015-01-01

    Workability is a key performance criterion for mining cemented tailing backfill, which should be defined in terms of rheological parameters such as yield stress and plastic viscosity. Cemented tailing backfill is basically composed of mill tailings, Portland cement, or blended cement with supplementary cement material (fly ash and blast furnace slag) and water, among others, and it is important to characterize relationships between paste components and rheological properties to optimize the w...

  16. Leaching of tritium from a cement composite

    International Nuclear Information System (INIS)

    Leaching of tritium from cement composites into an aqueous phase has been studied to evaluate the safety of incorporation of the tritiated liquid waste into cement. Leaching tests were performed by the method recommended by the International Atomic Energy Agency. The Leaching fraction was measured as functions of waste-cement ratio (Wa/C), temperature of leachant and curing time. The tritium leachability of cement in the long term test follows the order: alumina cement portland cement slag cement. The fraction of tritium leached increases with increasing Wa/C and temperature and decreasing curing period. A deionized water as a leachant gives a slightly higher leachability than synthetic sea water. The amount leached of tritium from a 200 l drum size specimen was estimated on the basis of the above results. (author)

  17. Characteristics solidified cement waste using heavy concrete and light concrete paste generated from KRR-2 and UCP

    International Nuclear Information System (INIS)

    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∼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 (Ca3SiO5) and constitutes 50-70%, decalcium silicate (Ca2SiO4), tricalcium aluminate (Ca3Al2O6), and calcium aluminoferrite (Ca4Al2Fe2O10). 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 mutually strongly by hydrated cement paste. Radionuclides may be found

  18. Morphological properties of surface-treated carbon nanotubes in cement-based composites.

    Science.gov (United States)

    Wang, Baomin; Han, Yu; Zhang, Tingting

    2012-11-01

    The morphological properties of the multi-walled carbon nanotubes (MWCNTs) reinforced Portland cement composites were investigated. MWCNTs with addition of up to 0.15 wt% of cement were incorporated to Portland cement with a water to cement ratio of 0.35. The porosity and pore size distribution of the composites were measured by mercury intrusion porosimetry (MIP), and the results indicate that the cement doped with MWCNTs obtained lower porosity and concentrated pore size distribution. The microstructure was analyzed by field emission scanning electron microscopy (FE SEM) and energy dispersive spectroscopy (EDS). It is shown that MWCNTs act as bridges and networks across cracks and voids. PMID:23421224

  19. 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

  20. 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.

  1. Behavior of multi-walled carbon nanotubes on the porosity and microstructure of cement-based materials

    International Nuclear Information System (INIS)

    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.

  2. Estimating the chloride transport in cement paste

    OpenAIRE

    Princigallo, A.

    2012-01-01

    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 prov...

  3. 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....

  4. Transport of anhydrous ammoniac - risk assessment

    International Nuclear Information System (INIS)

    This risk analysis of anhydrous ammonia transport in France was done within a study initiated by the Department of dangerous goods of the Ministry of transport. The study deals with the road and rail transportation of bulk anhydrous ammonia. After analysis of transport system and traffic, the transport accident risks are estimated, as well as their distribution on the French territory. Finally after a synthesis of results, a number of safety measures to be undertaken were identified. This is a joint study of SMC-CEPN, with a specific role of SEMA-METRA-CONSEIL concerning the traffic frequency, and the center for risk evaluation concerning nuclear safety

  5. 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. PMID:27059444

  6. Cancer Mortality and Incidence in Cement Industry Workers in Korea

    OpenAIRE

    Koh, Dong-Hee; Kim, Tae-Woo; Jang, Seung Hee; Ryu, Hyang-Woo

    2011-01-01

    Objectives Cement contains hexavalent chromium, which is a human carcinogen. However, its effect on cancer seems inconclusive in epidemiologic studies. The aim of this retrospective cohort study was to elucidate the association between dust exposure in the cement industry and cancer occurrence. Methods The cohorts consisted of male workers in 6 Portland cement factories in Korea. Study subjects were classified into five groups by job: quarry, production, maintenance, laboratory, and office wo...

  7. A positron annihilation study on the hydration of cement pastes

    International Nuclear Information System (INIS)

    Positron annihilation lifetime spectroscopy experiments were carried out in various ordinary Portland cement pastes, in an attempt to monitor the porosity of the pastes. It is found that positronium intensity is well correlated to the time evolution of the total porosity and it is influenced by the water-to-cement ratio. This parameter is also sensitive to the delayed hydration process induced by adding methanol to the water-cement mixture

  8. Influence of Pore Structure on Compressive Strength of Cement Mortar

    OpenAIRE

    Haitao Zhao; Qi Xiao; Donghui Huang; Shiping Zhang

    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 r...

  9. 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.

  10. 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.

  11. 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.

  12. Optimisation and adoption of slag based cement for conditioning of intermediate level alkaline radioactive liquid waste in CLEAR-V campaign

    International Nuclear Information System (INIS)

    The ILW is normally treated by resorcinol formaldehyde special type of resin. Another method for management of ILW is by conditioning in cement matrix. Various waste to cement ratios have been tried at lab and plant scale by taking slag based cement and ordinary portland cement. The cement waste products were evaluated for various properties. The final selected waste to cement ratio has been successfully adopted on the plant scale for conditioning of 140 m3 of ILW at SWMF. (author)

  13. 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.

  14. Analyses of microstructural properties of VA/VeoVA copolymer modified cement pastes

    OpenAIRE

    Carlos Eduardo M. Gomes; Osny P. Ferreira

    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...

  15. Manufacture of high purity low arsenic anhydrous hydrogen fluoride

    International Nuclear Information System (INIS)

    A process for manufacturing anhydrous hydrogen fluoride with reduced levels of arsenic impurity from arsenic contaminated anhydrous hydrogen fluoride is described which comprises: (a) contacting the anhydrous hydrogen fluoride with an effective amount of hydrogen peroxide to oxidize the arsenic impurity in the presence of a catalyst which comprises a catalytic amount of (i) molybdenum or an inorganic molybdenum compound and (ii) a phosphate compound, at a temperature and for a period of time sufficient to oxidize volatile trivalent arsenic impurities in the anhydrous hydrogen fluoride to non-volatile pentavalent arsenic compounds, and (b) distilling the resulting mixture and recovering anhydrous hydrogen fluoride with reduced levels of arsenic impurity

  16. 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 \

  17. Durability and compressive strength of blast furnace slag-based cement grout for special geotechnical applications

    OpenAIRE

    Ortega Álvarez, José Marcos; Pastor Navarro, José Luis; Albaladejo Ruiz, Arturo; Sánchez Martín, Isidro; Climent, Miguel-Ángel

    2014-01-01

    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 prepar...

  18. Cement with silica fume and granulated blast-furnace slag: strength behavior and hydration

    OpenAIRE

    Bonavetti, V. L.; Castellano, C.; Donza, H.; Rahhal, V.F.; Irassar, E. F.

    2014-01-01

    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 a...

  19. Effect of supplementary cementing materials on the concrete corrosion control

    International Nuclear Information System (INIS)

    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

  20. 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.

  1. Prediction of chloride ingress and binding in cement paste

    DEFF Research Database (Denmark)

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

    2007-01-01

    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...... steady state diffusion however. It simply implies that incremental increases in the concentration of diffusing ions in the pore solution will rapidly re-equilibrate with the hydrates present locally, where, the greater the ratio of bound to free ions, the greater the buffering effect which slows down the...

  2. 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.

  3. 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.

  4. Adsorption of Superplasticizers in Fly Ash Blended Cement Pastes and Its Rheological Effects

    Institute of Scientific and Technical Information of China (English)

    CHEN Wei; SHEN Peiliang; SHUI Zhonghe; FAN Jianfeng

    2012-01-01

    The adsorption of superplasticizers in fly ash blended cement paste and its rheological effects were investigated.It is shown that the absorption of superplasticizer on portland cement particles is very different from that on fly ash particles.The fly ash particles have smooth surfaces and are negatively charged,so its adsorption capacity is weaker than the portland cement particles.The amount of adsorbed SP in the fly ash blended cement paste depends highly on the replacement proportion of portland cement with fly ash,and to a much less extent on the nature of the fly ash.However,the amount of adsorbed superplasticizer does not correspond well the ζ-potential of the solid particles,due the strong adsorbing capacities of the Portland cement particles.When fly ash replaces portland cement in the paste,the rheological behavior is radically changed,which is closely related to the fineness and density of the ash.The packing and agglomeration of the solid particles are the controlling factors on the rheological parameters of the fresh paste,instead of the amount and type of adsorbed superplasticizer.

  5. Retention of alkali ions by hydrated low-pH cements: Mechanism and Na+/K+ selectivity

    International Nuclear Information System (INIS)

    Low-pH cements, also referred to as low-alkalinity cements, can be designed by replacing significant amounts of Portland cement by pozzolanic materials. Their pore solution is characterized by a pH near 11, and an alkali concentration much lower than that of Portland cement. This work investigates the retention of sodium and potassium by a hydrated low-pH cement comprising 60% Portland cement and 40% silica fume. It is shown that sorption of potassium is higher than that of sodium and mainly results from counterion charge balancing of the C-S-H negative surface charge. To explain the greater retention of potassium compared to sodium, it is postulated that potassium, unlike sodium, may enter the interlayer of C-S-H to compensate the negative charges in the interlayer, in addition to the external surfaces. This assumption is supported by structural characterization of C-S-H using X-ray diffraction

  6. 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 ......, 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.......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...

  7. WAYS TO SAVE FUEL IN THE PORTLAND CEMENT CLINKER PRODUCTION / ПУТИ ЭКОНОМИИ ТОПЛИВА ПРИ ПРОИЗВОДСТВЕ КЛИНКЕРА ПОРТЛАНДЦЕМЕНТА

    Directory of Open Access Journals (Sweden)

    Ustinova Yu. V. / Устинова Юлия Валерьевна

    2014-12-01

    Full Text Available The article considers such ways of saving fuel in the production of Portland cement clinker as reduction of the moisture content of the sludge, the use of various fuel-containing waste with simultaneous solution of environmental problems as fuel, reduction of the firing temperature of the clinker of Portland cement by the use of mineralizers / Рассмотрены такие пути экономии топлива при производстве клинкера портландцемента, как снижение влажности шлама, использование в качестве топлива различных топливосодержащих отходов с одновременным решением экологических проблем, снижение температуры обжига клинкера портландцемента путем применения минерализаторов

  8. The interaction between nuclear waste glass and cement

    International Nuclear Information System (INIS)

    The interaction between simulated reference waste glasses SON68 and SM539 and cement has been studied in suspensions of Ordinary Portland Cement and synthetic young cement water with pH 13.5 at 30 C. The cement appears to trigger glass dissolution by consumption of glass matrix components. This leads to fast glass dissolution at a constant rate with formation of a porous gel layer on the glass. This is probably due mostly to the reaction of Si from the glass with portlandite, forming CSH phases. After consumption of the portlandite, the glass alteration rate is expected to decrease. (authors)

  9. Soft X-ray Microscopy of Green Cements

    Science.gov (United States)

    Monteiro, P. J. M.; Mancio, M.; Kirchheim, A. P.; Chae, R.; Ha, J.; Fischer, P.; Tyliszczak, T.

    2011-09-01

    The present status of the cement and concrete industry is not sustainable. The production of Portland cement is responsible for 7% of the CO2 emissions in the world and existing reinforced concrete infrastructure is deteriorating at a fast pace. The change in the existing technology requires new developments in our understanding of the nanostructure of hydration products and the complex deterioration reactions. We have been developing an elaborate research program to advance the existing cement and concrete science by characterizing its nanostructure by synchrotron radiation. A new generation of green cements is being studied using high-resolution soft x-ray microscopy at the nano-level.

  10. Soft X-ray Microscopy of Green Cements

    International Nuclear Information System (INIS)

    The present status of the cement and concrete industry is not sustainable. The production of Portland cement is responsible for 7% of the CO2 emissions in the world and existing reinforced concrete infrastructure is deteriorating at a fast pace. The change in the existing technology requires new developments in our understanding of the nanostructure of hydration products and the complex deterioration reactions. We have been developing an elaborate research program to advance the existing cement and concrete science by characterizing its nanostructure by synchrotron radiation. A new generation of green cements is being studied using high-resolution soft x-ray microscopy at the nano-level.

  11. Immobilisation of ion exchange resins in cement: final report

    International Nuclear Information System (INIS)

    The removal of activity from spent decontaminating solutions eg LOMI can be achieved using organic ion exchange resins. These resins can be successfully immobilised in cement based matrices. The optimum cement system contained 10% Ordinary Portland Cement 84% gg Blast Furnace Slag, 6% Microsilica with a water cement ratio of 0.5 and a dry resin loading of 36% with respect to total weight. This information was successfully scaled up to 200 litres giving a product with acceptable compressive strength, dimensional stability and elastic modulus. Storage of samples under water appears to have no detrimental effects on the product's properties. (author)

  12. Interactions between cement grouts and sulphate bearing ground water

    International Nuclear Information System (INIS)

    The physical, chemical and mineralogical properties of mixtures of Ordinary Portland cement and blastfurnace slag or pulverized fuel ash, exposed to a sulphate-bearing ground water at different temperatures and pressures, were investigated in order to assess the long term durability of cements for encapsulating radioactive waste and backfilling a repository. The effect of the ground water on the chemical and mineralogical characteristics of the cements is minimal. Calcite and C-S-H are present in all the samples and are durable throughout the test. Dimensional changes in the cements during setting and curing may cause weaknesses in the materials which may increase the effects of a percolating ground water. (author)

  13. 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.

  14. Stabilization/solidification of hazardous and radioactive wastes with alkali-activated cements

    International Nuclear Information System (INIS)

    This paper reviews progresses on the use of alkali-activated cements for stabilization/solidification of hazardous and radioactive wastes. Alkali-activated cements consist of an alkaline activator and cementing components, such as blast furnace slag, coal fly ash, phosphorus slag, steel slag, metakaolin, etc., or a combination of two or more of them. Properly designed alkali-activated cements can exhibit both higher early and later strengths than conventional portland cement. The main hydration product of alkali-activated cements is calcium silicate hydrate (C-S-H) with low Ca/Si ratios or aluminosilicate gel at room temperature; C-S-H, tobmorite, xonotlite and/or zeolites under hydrothermal condition, no metastable crystalline compounds such as Ca(OH)2 and calcium sulphoaluminates exist. Alkali-activated cements also exhibit excellent resistance to corrosive environments. The leachability of contaminants from alkali-activated cement stabilized hazardous and radioactive wastes is lower than that from hardened portland cement stabilized wastes. From all these aspects, it is concluded that alkali-activated cements are better matrix for solidification/stabilization of hazardous and radioactive wastes than Portland cement

  15. 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

    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兰水门汀(WPC)和MTA多。根管充填材料的溶解性影响根管充填的封闭性,总体而言,MTA和PC的根尖封闭性能相当。良好的口腔材料应具有适当的凝固时间,在MTA和PC中加入氯化钙或甲酸钙可缩短凝固时间。材料微粒的大小可影响其封闭性、凝固时间、抗压强度和耐磨性能等。WPC的平均粒径大于MTA,其抗压强度小于MTA,但是加有金粉的WPC的抗压强度与MTA相当。MTA和PC皆无细胞毒性和遗传毒性,两者对中国仓鼠卵巢细胞的DNA的影响无差异。MTA和PC对藤黄微球菌、金黄色葡萄球菌和大肠埃希菌等多种微生物有抑菌性能。MTA和PC均可促硬组织矿化,皆可导致牙体牙冠变色,但PC的变色轻于MTA。MTA因凝固时间长、牙体变色、不易取出和价格昂贵等,使其应用受限;而PC则可以作为一种经济的有效的MTA替代材料应用于牙体修复,但其远期疗效还不确定,需要更长时间的随访评估。%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

  16. 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.

  17. Pore structure of blended cement paste by means of pressurization¿depressurization cycling mercury intrusion porosimetry

    NARCIS (Netherlands)

    Zhang, Y.; Wu, B.; Zhou, J.; Ye, G.; Shui, Z.

    2014-01-01

    Concrete containing supplementary cementitious materials (SCMs) has different durability properties from that containing pure Portland cement. The durability of concrete is always associated with the properties of microstructure, especially pore structure. Pressurization–Depressurization Cycling Mer

  18. Magnesia-Based Cements: A Journey of 150 Years, and Cements for the Future?

    Science.gov (United States)

    Walling, Sam A; Provis, John L

    2016-04-13

    This review examines the detailed chemical insights that have been generated through 150 years of work worldwide on magnesium-based inorganic cements, with a focus on both scientific and patent literature. Magnesium carbonate, phosphate, silicate-hydrate, and oxysalt (both chloride and sulfate) cements are all assessed. Many such cements are ideally suited to specialist applications in precast construction, road repair, and other fields including nuclear waste immobilization. The majority of MgO-based cements are more costly to produce than Portland cement because of the relatively high cost of reactive sources of MgO and do not have a sufficiently high internal pH to passivate mild steel reinforcing bars. This precludes MgO-based cements from providing a large-scale replacement for Portland cement in the production of steel-reinforced concretes for civil engineering applications, despite the potential for CO2 emissions reductions offered by some such systems. Nonetheless, in uses that do not require steel reinforcement, and in locations where the MgO can be sourced at a competitive price, a detailed understanding of these systems enables their specification, design, and selection as advanced engineering materials with a strongly defined chemical basis. PMID:27002788

  19. Optical evaluation on the setting of cement paste

    International Nuclear Information System (INIS)

    In the construction area, one of the most widely used cement is the CPC 30R, it is a hydraulic binder consisting of CaO, SiO2, Al2O3 and Fe2O3, when mixed with water forms cement pastes and its four crystallographic phases start to hydrate. The diffuse reflection on cement paste can give an indication of the behaviour on optical properties on the hydration of the cement and early formation products. In this study, Portland cement (CPC) pastes were prepared with 0.45 a water to cement ratio (w/c). This work is aimed to evaluate the optical properties of cement pastes on the hydration reaction during the first 24 hours by measuring the intensity of diffuse reflection changes

  20. Carbonatation Influence on Fly Ash and Portland Cement Mortars

    OpenAIRE

    P.L. Valdez–Tamez; A. Durán–Herrera; G. Fajardo–San Miguel; C.A. Juárez–Alvarado

    2009-01-01

    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...

  1. Solidification of low-level radioactive wastes in masonry cement

    International Nuclear Information System (INIS)

    Portland cements are widely used as solidification agents for low-level radioactive wastes. However, it is known that boric acid wastes, as generated at pressurized water reactors (PWR's) are difficult to solidify using ordinary portland cements. Waste containing as little as 5 wt % boric acid inhibits the curing of the cement. For this purpose, the suitability of masonry cement was investigated. Masonry cement, in the US consists of 50 wt % slaked lime (CaOH2) and 50 wt % of portland type I cement. Addition of boric acid in molar concentrations equal to or less than the molar concentration of the alkali in the cement eliminates any inhibiting effects. Accordingly, 15 wt % boric acid can be satisfactorily incorporated into masonry cement. The suitability of masonry cement for the solidification of sodium sulfate wastes produced at boiling water reactors (BWR's) was also investigated. It was observed that although sodium sulfate - masonry cement waste forms containing as much as 40 wt % Na2SO4 can be prepared, waste forms with more than 7 wt % sodium sulfate undergo catastrophic failure when exposed to an aqueous environment. It was determined by x-ray diffraction that in the presence of water, the sulfate reacts with hydrated calcium aluminate to form calcium aluminum sulfate hydrate (ettringite). This reaction involves a volume increase resulting in failure of the waste form. Formulation data were identified to maximize volumetric efficiency for the solidification of boric acid and sodium sulfate wastes. Measurement of some of the waste form properties relevant to evaluating the potential for the release of radionuclides to the environment included leachability, compression strengths and chemical interactions between the waste components and masonry cement. 15 refs., 19 figs., 9 tabs

  2. Studies Involving Immobilization Of Hazardous Wastes In Cement-ilmenite Matrix

    International Nuclear Information System (INIS)

    Ilmenite was added to Ordinary Portland Cement to Modify the characteristic properties of the matrix as density, compressive strength and thermal stability . Coal tar and radiocesium were solidified as hazardous waste in cement-ilmenite matrix. The physical properties as density, sitting times and porosity were studied. The mechanical properties as compressive strength values and the chemical properties as leaching were measured

  3. Cement for oil well developed from ordinary cement: characterization physical, chemical and mineralogical

    International Nuclear Information System (INIS)

    This work aims to characterize a new type of cement produced from the mixture of ordinary Portland cement, which can be used as an option in the cementing of oil wells. To enable this work we used the method of lineal programming for the new cement composition, then conducted tests to characterize through particle size analysis by laser diffraction, chemical analysis by EDX, TGA, X-ray diffraction, time grip, resistance to compression. The overall result showed that the new cement had made low-C3A, takes more time to the CPP, thermal stability up to 500 ° C, the kinetics of hydration and low levels of major components consistent with the specifications of ABNT. (author)

  4. Wet versus dry cement pastes and concretes: a mathematical approach to their strength and fracture properties

    International Nuclear Information System (INIS)

    The fracture process of a continuous matrix in a porous medium under the combined effect of filtration and external mechanical loads is considered. Taking into account the differences between the failure mechanisms of cement paste under tension and its failure mechanisms under compression, an analytical approach to the relation between water flow and fracture in saturated porous Portland cement pastes is developed. The well known differences in behaviour between the flexural and compressive strengths of wet and dry Portland cement pastes is explained. The extension of the obtained results to the flexural and compressive strength of normal concrete is briefly discussed, including suggestions for further experimental and digital simulation work

  5. Natural Radioactivity in Tanzania Cements and their Raw Materials

    OpenAIRE

    Aloyce Isaya Amasi; Kelvin Mark Mtei; Ijumba Jasper Nathan; Pawel Jodłowski; Chau Nguyen Dinh

    2014-01-01

    This paper presents the study of natural radioactivity in Tanzania Portland cements and their raw materials. Samples collected as raw materials were pozzolan, sandstone, limestone, clay, gypsum and cement as finished products. The natural radioactivity due to the presence of radium 226Ra, thorium 232Th and potassium 40K were measured by means of gamma spectrometer coupled with HPGe detector. The mean measured activity concentrations of 226Ra, thorium 232Th and potassium 40K in the raw materia...

  6. Hydration and dimensional stability of calcium aluminate cement based systems

    OpenAIRE

    Bizzozero, Julien

    2014-01-01

    Calcium aluminate cements (CAC) are often used in combination with calcium sulfate and Portland cement for special applications where rapid setting, rapid drying and shrinkage compensation are required. A growing fraction of the clinker, which has the highest CO2 intensity, is being replaced by supplementary cementitious materials (SCM). These SCM are usually from industrial by-products such as slag, fly ashes or can simply be raw materials such as limestone. This project aims at replacing th...

  7. Rheological and hydration characterization of calcium sulfoaluminate cement pastes

    OpenAIRE

    García-Maté, Marta; Santacruz, Isabel; de la Torre, Ángeles G.; León-Reina, Laura; Aranda, Miguel A. G.

    2012-01-01

    Calcium sulfoaluminate (CSA) cements are currently receiving a lot of attention because their manufacture produces less CO2 than ordinary Portland cement (OPC). However, it is essential to understand all parameters which may affect the hydration processes. This work deals with the study of the effect of several parameters, such as superplasticizer (SP), gypsum contents (10, 20 and 30 wt%) and w/c ratio (0.4 and 0.5), on the properties of CSA pastes during early hydration. This characteriza...

  8. 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.

  9. 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.

  10. 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...

  11. 75 FR 20778 - Security Zone; Portland Rose Festival Fleet Week, Willamette River, Portland, OR

    Science.gov (United States)

    2010-04-21

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA87 Security Zone; Portland Rose Festival Fleet Week... Hawthorne and Steel Bridges in Portland, Oregon during the Portland Rose Festival Fleet Week from June 2... and other vessels participating in Fleet Week as well as the maritime public in general and will do...

  12. Hydration study of limestone blended cement in the presence of hazardous wastes containing Cr(VI)

    International Nuclear Information System (INIS)

    Considering the increasing use of limestone cement manufacture, the present paper tends to characterize limestone behavior in the presence of Cr(VI). The research reported herein provides information regarding the effect of Cr(VI) from industrial wastes in the limestone cement hydration. The cementitious materials were ordinary Portland cement, as reference, and limestone blended cement. The hydration and physicomechanical properties of cementitious materials and the influence of chromium at an early age were studied with X-ray diffraction (XRD), infrared spectroscopy (FTIR), conductimetric and mechanical tests. Portland cement pastes with the addition of Cr(VI) were examined and leaching behavior with respect to water and acid solution were investigated. This study indicates that Cr(VI) modifies the rate and the components obtained during the cement hydration

  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. 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.

  15. Continuous monitoring of the zinc-phosphate acid-base cement setting reaction by proton nuclear magnetic relaxation

    International Nuclear Information System (INIS)

    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. [copyright] 2001 American Institute of Physics

  16. Performance characteristics of concrete based on a ternary calcium sulfoaluminate–anhydrite–fly ash cement

    OpenAIRE

    Ioannou, Socrates; Paine, Kevin; Reig Cerdá, Lucía; Quillin, Keith

    2015-01-01

    This paper reports an assessment of the performance of concrete based on a calcium sulfoaluminate–anhydrite–fly ash cement combination. Concretes were prepared at three different w/c ratios and the properties were compared to those of Portland cement and blast-furnace cement concretes. The assessment involved determination of mechanical and durability properties. The results suggest that an advantageous synergistic effect between and ettringite and fly ash (Ioannou et al., 2014) was reflected...

  17. Behavior of limestone filler cement mortars exposed to magnesium sulfate attack

    OpenAIRE

    Senhadji Y.; Mouli M.; Escadeillas G.; Khelafi A.; Bennosman A. S.; Chihaoui R.

    2014-01-01

    In the cement production industry, looking for a less expensive binder using industrial waste and natural resources has become a major concern for the deficit level in the manufacture of Portland cement. However, despite the technical, economic and environmental benefits brought by the use of blended cements, they are associated with disadvantages. The objective of this paper is to study the effects of the incorporation of limestone fillers on the mechanical properties and durability of morta...

  18. Influence of the calcium sulfate source on the rheological behaviour of calcium sulfoaluminate cement pastes

    OpenAIRE

    Santacruz, Isabel; García-Maté, Marta; G. Aranda, Miguel Ángel; De la Torre, Ángeles G.

    2013-01-01

    Calcium sulfoaluminate (CSA) cements are receiving increasing attention since their manufacture produces much less CO2 than ordinary Portland cement (OPC) [1]. In addition, they show interesting properties such as high early-age strengths, short setting times and impermeability. The main uses of these CSA cements are for quick repairs and pre-cast products or floor concrete applications. They are prepared by mixing the clinker with different amounts of a calcium sulfate set regulator such as ...

  19. Calcium Aluminate Cement Hydration Model

    Directory of Open Access Journals (Sweden)

    Matusinović, T.

    2011-01-01

    Full Text Available Calcium aluminate cement (AC is a very versatile special cement used for specific applications. As the hydration of AC is highly temperature dependent, yielding structurally different hydration products that continuously alter material properties, a good knowledge of thermal properties at early stages of hydration is essential. The kinetics of AC hydration is a complex process and the use of single mechanisms models cannot describe the rate of hydration during the whole stage.This paper examines the influence of temperature (ϑ=5–20 °C and water-to-cement mass ratio (mH /mAC = 0.4; 0.5 and 1.0 on hydration of commercial iron-rich AC ISTRA 40 (producer: Istra Cement, Pula, Croatia, which is a part of CALUCEM group, Figs 1–3. The flow rate of heat generation of cement pastes as a result of the hydration reactions was measured with differential microcalorimeter. Chemically bonded water in the hydrated cement samples was determined by thermo-gravimetry.Far less heat is liberated when cement and water come in contact for the first time, Fig. 1, than in the case for portland cement (PC. Higher water-to-cement ratio increases the heat evolved at later ages (Fig. 3 due to higher quantity of water available for hydration. A significant effect of the water-to-cement ratio on the hydration rate and hydration degree showed the importance of water as being the limiting reactant that slows down the reaction early. A simplified stoichiometric model of early age AC hydration (eq. (8 based on reaction schemes of principal minerals, nominally CA, C12A7 and C4AF (Table 1, was employed. Hydration kinetics after the induction period (ϑ < 20 °C had been successfully described (Fig. 4 and Table 2 by a proposed model (eq. (23 which simultaneously comprised three main mechanisms: nucleation and growth, interaction at phase boundary, and mass transfer. In the proposed kinetic model the nucleation and growth is proportional to the amount of reacted minerals (eq

  20. Determination of appropriate mix ratios for concrete grades using Nigerian Portland-limestone grades 32.5 and 42.5

    Directory of Open Access Journals (Sweden)

    Kazeem Kayode ADEWOLE

    2015-05-01

    Full Text Available The construction of buildings by incompetent craftsmen and the use of low quality building materials, including low quality concrete have been identified in the literature as two of the major reasons for the incessant collapse of building in Nigeria. The roadside craftsmen/artisans usually/generally construct buildings using 1:2:4 cement-fine aggregate-large aggregate mix ratio irrespective of the cement strength class. In this paper, the investigation conducted to determine the appropriate concrete mix ratios required to produce Class 20/25 and Class 25/30 concretes commonly used for design of building structural members using the Portland-limestone cement grades 32.5 and 42.5 that are available in the Nigerian open market is presented. Investigation revealed that the cube compressive strength of 1:2:4 concrete produced with Portland-limestone cement grade 32.5 is less than the minimum 25MPa required for concrete Class 20/25 and a richer 1:1.5:3 concrete produced with Portland-limestone cement grade 32.5 may be needed to produce concrete Class 20/25. Investigation also revealed that Portland-limestone cement grade 32.5 may not be suitable for the production of concrete class 25/30 with cube compressive strength of 30MPa as the cube compressive strength of 1:1:2 concrete produced with Portland-limestone cement grade 32.5 may not attain 30MPa. Concrete strength classes 20/25 and class 25/30 can be produced with Portland-limestone cement grade 42.5 using 1:2:4 and 1:1.5:3 mix ratios respectively. To produce concrete with strength class C20/25 which is the minimum concrete strength class recommended for the construction of the load-bearing building structural members using the 1:2:4 mix ratio, Portland-limestone cement grade 42.5 is required.

  1. 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

  2. Immobilization of radioactive waste in cement based matrices

    International Nuclear Information System (INIS)

    The kinetics of reaction between cement and clinoptilolite are elucidated and rate equations containing temperature dependent constants derived for this reaction. Variations in clinoptilolite particle size and their consequences to reactivity are assessed. The presence of pozzolanic agents more reactive than clinoptilolite provides sacrificial agents which are partially effective in lowering the clinoptilolite reactivity. Blast furnace slag-cements have been evaluated and the background literature summarized. Experimental studies of the pore fluid in matured slag-cements show that they provide significantly more immobilization for Cs than Portland cement. The distribution of Sr in cemented waste forms has been examined, and it is shown that most of the chemical immobilization potential in the short term is likely to be associated with the aluminate phases. The chemical and structural nature of these are described. Carbonation studies on real cements are summarized. (author)

  3. Functional polymers for anhydrous proton transport

    Science.gov (United States)

    Chikkannagari, Nagamani

    Anhydrous proton conducting polymers are highly sought after for applications in high temperature polymer electrolyte membrane fuel cells (PEMFCs). N-heterocycles (eg. imidazole, triazole, and benzimidazole), owing to their amphoteric nature, have been widely studied to develop efficient anhydrous proton transporting polymers. The proton conductivity of N-heterocyclic polymers is influenced by several factors and the design and development of polymers with a delicate balance among various synergistic and competing factors to provide appreciable proton conductivities has been a challenging task. In this thesis, the proton transport (PT) characteristics of polymers functionalized with two diverse classes of functional groups--- N-heterocycles and phenols have been investigated and efforts have been made to develop the molecular design criteria for the design and development of efficient proton transporting functional groups and polymers. The proton conduction pathway in 1H-1,2,3-triazole polymers is probed by employing structurally analogous N-heterocyclic (triazole, imidazole, and pyrazole) and benz-N-heterocyclic (benzotriazole, benzimidazole, and benzopyrazole) polymers. Imidazole-like pathway was found to dominate the proton conductivity of triazole and pyrazole-like pathway makes only a negligible contribution, if any. Polymers containing benz-N-heterocycles exhibited higher proton conductivity than those with the corresponding N-heterocycles. Pyrazole-like functional groups, i.e. the molecules with two nitrogen atoms adjacent to each other, were found not to be good candidates for PT applications. A new class of proton transporting functional groups, phenols, has been introduced for anhydrous PT. One of the highlighting features of phenols over N-heterocycles is that the hydrogen bond donor/acceptor reorientation can happen on a single -OH site, allowing for facile reorientational dynamics in Grotthuss PT and enhanced proton conductivities in phenolic polymers

  4. Treating of cement curing with supercritical fluid carbon dioxide

    International Nuclear Information System (INIS)

    The main curing reactions of a portland cement are the formation of portlandite, Ca(OH)2, and calcium silicate hydrates, CSH. In nature, the cement extracts CO2 from air and convert the calcium hydroxide and CSH to calcium carbonate(CaCO3), calcite. By this process, chemically stable and mechanically enhanced cement is formed. By exposing an OPC to supercritical CO2 (SCCO2), the carbonate reaction was greatly accelerated. XRD analysis of experimental sample showed the acceleration of carbonate reaction and the test of compressive strength showed the mechanical enhancement

  5. Occupational radioactive contamination of cement handlers of the civil construction

    International Nuclear Information System (INIS)

    Due to their occupational activities, several classes of workers are exposed to radioactive contamination by materials they handle and that contain traces of uranium and its descendants. This is the case of people that work in the civil construction and that currently handle Portland cement. Among other radioactive elements, cement contains the highly radiotoxic polonium-210 which may promote skin cancer because of its high specific activity and high LET α-particle it emits. Concentrations of polonium-210 are reported for urine, hair and skin smear of workers of the civil construction that usually handle cement. The results are compared to a control group. (author)

  6. CEMENT SLURRIES FOR GEOTHERMAL WELLS CEMENTING

    OpenAIRE

    Nediljka Gaurina-Međimurec; Davorin Matanović; Gracijan Krklec

    1994-01-01

    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...

  7. Radiolytic preparation of anhydrous tin (2) chloride

    Science.gov (United States)

    Philipp, W. H.; Marsik, S. J.

    1973-01-01

    Anhydrous tin (2) chloride (SnCl2) is prepared by radiolysis with high energy electrons of a tin (4) chloride (SnCl4) solution in heptane. The SnCl4 is reduced to insoluble SNCl2. The energy yield, G(SnCl2), molecules of SnCl2, produced per 100 eV, increases with SnCl4 concentration from 1.6 at 0.15 M SnCl4 to 3.1 at 3.0 M SnCl4. Other parameters such as temperature total dose and beam current have little influence on G(SnCl2). The method may be used to prepare other metal halides if the higher valence, more covalent metal halide is soluble in aliphatic hydrocarbons and the lower more ionic metal halide is insoluble. The reaction mechanism is discussed; the radiolysis of both heptane and SnCl4 is involved. At high SnCl4 concentration G(SnCl2) appears to be limited by the yield of SnC13 radicals.

  8. Alternativas analíticas para determinação de ferro e titânio em cimento Portland

    OpenAIRE

    Franco Jr. Jorge de O.; Korn Maria das Graças A.; Costa Antonio Celso S.; Santos Jr. Anibal de Freitas; Teixeira Leonardo S. G.

    2001-01-01

    In the present work four different analytical methodologies were studied for the determination of iron and titanium in Portland cement. The cement samples were dissolved with hot HCl and HF, being compared Fe and Ti concentrations through four analytical methods: molecular absorption spectrophotometry using the reagents 1,2-hydroxybenzene-3,5-disulfonic acid (Tiron) and the 5-chloro-salicylic acid (CSA), inductively coupled plasma atomic emission spectrometry (ICP-AES) and flame atomic absorp...

  9. 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

  10. Neutron Scattering Studies of Cement

    Science.gov (United States)

    Allen, Andrew

    2010-03-01

    Despite more than a century of research, basic questions remain regarding both the internal structure and the role of water in Ordinary Portland cement (OPC) concrete, the world's most widely used manufactured material. Most such questions concern the primary hydration product and strength-building phase of OPC paste, the calcium silicate hydrate (C-S-H) gel. When cement and water are mixed, this phase precipitates as clusters of nanoscale (nearly amorphous) colloidal particles with an associated water-filled inter-particle pore system. Most attempts to characterize the C-S-H gel and the behavior of the associated water involve drying or other processes that, themselves, change the bound water content within and around the gel. Neutron scattering methods do not suffer from this disadvantage. Furthermore, the neutron isotope effect and the neutron's sensitivity to molecular motion have enabled considerable progress to be made in recent years by: (i) determining the C-S-H composition, density and gel structure in small-angle neutron scattering (SANS) H/D contrast variation studies; (ii) elucidating the changing state of water within cement as hydration progresses using quasielastic neutron scattering (QENS); and (iii) measuring the production and consumption of nanoscale calcium hydroxide (CH), a by-product of cement hydration that co-exists with the C-S-H gel, using inelastic neutron scattering (INS). These experiments have provided new insights into the physics and chemistry of cement hydration, and have implications for the design of new concretes with pozzolanic cement additions that are intended to address environmental concerns and sustainability issues.

  11. 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.

  12. 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.

  13. Reuse of grits waste for the production of soil--cement bricks.

    Science.gov (United States)

    Siqueira, F B; Holanda, J N F

    2013-12-15

    This investigation focuses on the reuse of grits waste as a raw material for replacing Portland cement by up to 30 wt.% in soil-cement bricks. The grits waste was obtained from a cellulose factory located in south-eastern Brazil. We initially characterized the waste sample with respect to its chemical composition, X-ray diffraction, fineness index, morphology, pozzolanic activity, and pollution potential. Soil-cement bricks were then prepared using the waste material and were tested to determine their technological properties (e.g., water absorption, apparent density, volumetric shrinkage, and compressive strength). Microstructural evolution was accompanied by confocal microscopy. It was found that the grits waste is mainly composed of calcite (CaCO3) particles. Our results indicate that grits waste can be used economically, safely, and sustainably at weight percentages of up to 20% to partially replace Portland cement in soil-cement bricks. PMID:24140481

  14. Experimental evaluation of cement materials for solidifying sodium nitrate

    International Nuclear Information System (INIS)

    Low-level liquid waste containing sodium nitrate is planned to be transformed to salt block by evaporation with sodium borate in the Low-level Waste Treatment Facility (LWTF), then salt block will be stored temporally. It should be important to investigate the method how to treat these liquid waste suitable to final disposal criteria that will be settled in future. Cement solidification is one of promising candidates because it has been achieved as the solidification material for the shallow land disposal. The research was conducted to evaluate applicability of various cement materials to solidification of sodium nitrate. The following cements were tested. Ordinary Portland Cement (OPC). Portland Blast-furnace Slag Cement; C type (PBFSC). Alkali Activated Slag Cement (AASC, supplied by JGC). The test results are as follows; (1) AASC is characterized by a high sodium nitrate loading (-70 wt%) compared with other types of cement material. High fluidity of the cement paste, high strength after solidification, and minimization of free water on the cement paste are achieved under all test conditions. (2) OOPC and PBFSC produced free water on the cement paste in the early days and delayed the hardening period. 3 or more days are required to harden evan with 30 wt% content of sodium nitrate. (3) Though PBFSC contains blast furnace slag similar to AASC, there is no advantage prior to OPC. To design an ideal cement conditioning system for sodium nitrate liquid waste in the LWTF, the further studies are necessary such as the simulated waste test, Kd test, pilot test, and layout design. (author)

  15. Evaluation of ternary blended cements for use in transportation concrete structures

    Science.gov (United States)

    Gilliland, Amanda Louise

    This thesis investigates the use of ternary blended cement concrete mixtures for transportation structures. The study documents technical properties of three concrete mixtures used in federally funded transportation projects in Utah, Kansas, and Michigan that used ternary blended cement concrete mixtures. Data were also collected from laboratory trial batches of ternary blended cement concrete mixtures with mixture designs similar to those of the field projects. The study presents the technical, economic, and environmental advantages of ternary blended cement mixtures. Different barriers of implementation for using ternary blended cement concrete mixtures in transportation projects are addressed. It was concluded that there are no technical, economic, or environmental barriers that exist when using most ternary blended cement concrete mixtures. The technical performance of the ternary blended concrete mixtures that were studied was always better than ordinary portland cement concrete mixtures. The ternary blended cements showed increased durability against chloride ion penetration, alkali silica reaction, and reaction to sulfates. These blends also had less linear shrinkage than ordinary portland cement concrete and met all strength requirements. The increased durability would likely reduce life cycle costs associated with concrete pavement and concrete bridge decks. The initial cost of ternary mixtures can be higher or lower than ordinary portland cement, depending on the supplementary cementitious materials used. Ternary blended cement concrete mixtures produce less carbon dioxide emissions than ordinary portland cement mixtures. This reduces the carbon footprint of construction projects. The barriers associated with implementing ternary blended cement concrete for transportation projects are not significant. Supplying fly ash returns any investment costs for the ready mix plant, including silos and other associated equipment. State specifications can make

  16. R7T7 glass alteration in the presence of mortar: effect of the cement grade

    International Nuclear Information System (INIS)

    R7T7 glass alteration was investigated in the presence of four mortars prepared from four different cement grades: 'CPA' Portland cement (mortar M1), CPA with pozzolana additive (M2), CPA with amorphous silica additive (M3) and 'CLK' blast furnace slag cement (M4). Glass specimens were also altered in Volvic mineral water and in a cement effluent. Glass corrosion in the cement media was greater than in Volvic water, but well below what could be expected from the high pH (approx 12.5). The relatively low alteration was probably related to the protective action of the calcium-enriched gel layer that formed at the glass surface. The glass corrosion rate was 2 to 3 times lower with cement containing pozzolana or silica gel additives or with CLK cement than with CPA cement alone. 8 refs., 8 figs

  17. Chromium solubility in anhydrous Phase B

    Science.gov (United States)

    Bindi, Luca; Sirotkina, Ekaterina A.; Bobrov, Andrey V.; Nestola, Fabrizio; Irifune, Tetsuo

    2016-02-01

    The crystal structure and chemical composition of a crystal of (Mg14- x Cr x )(Si5- x Cr x )O24 ( x ≈ 0.30) anhydrous Phase B (Anh-B) synthesized in the model system MgCr2O4-Mg2SiO4 at 12 GPa and 1600 °C have been investigated. The compound was found to be orthorhombic, space group Pmcb, with lattice parameters a = 5.900(1), b = 14.218(2), c = 10.029(2) Å, V = 841.3(2) Å3 and Z = 2. The structure was refined to R 1 = 0.065 using 1492 independent reflections. Chromium was found to substitute for both Mg at the M3 site (with a mean bond distance of 2.145 Å) and Si at the octahedral Si1 site (mean bond distance: 1.856 Å), according to the reaction Mg2+ + Si4+ = 2Cr3+. Such substitutions cause a reduction in the volume of the M3 site and an increase in the volume of the Si-dominant octahedron with respect to the values typically observed for pure Anh-B and Fe2+-bearing Anh-B. Taking into account that Cr3+ is not expected to be Jahn-Teller active, it appears that both the Cr3+-for-Mg and Cr3+-for-Si substitutions in the Anh-B structure decrease the distortion of the octahedra. Electron microprobe analysis gave the Mg13.66(8)Si4.70(6)Cr0.62(4)O24 stoichiometry for the studied phase. The successful synthesis of this phase provides new information for the possible mineral assemblages occurring in the Earth's deep upper mantle and shed new light on the so-called X discontinuity that has been observed at 275-345 km depth in several subcontinental and subduction zone environments.

  18. 77 FR 4006 - Foreign-Trade Zone 45-Portland, Oregon; Expansion of Manufacturing Authority; Epson Portland, Inc...

    Science.gov (United States)

    2012-01-26

    ... Foreign-Trade Zones Board Foreign-Trade Zone 45--Portland, Oregon; Expansion of Manufacturing Authority; Epson Portland, Inc. (Inkjet Ink Manufacturing); Portland, OR An application has been submitted to the... of the scope of manufacturing authority approved within Subzone 45F, on behalf of Epson Portland,...

  19. Immobilisation of ion exchange resins in cement

    International Nuclear Information System (INIS)

    Over the last seven years, Low Oxidation State Metal Ion reagents (LOMI) have been used to decontaminate the 100 MW(e) Steam Generating Heavy Water Ractor (SGHWR) at Winfrith. The use of these reagents has resulted in a dilute ionic solution containing activation products which are produced by corrosion of metallic components in the reactor. It has been demonstrated that the amount of activity in the solution can be reduced using organic ion exchanger resins. These resins consist of a cross linked polystyrene with sulphonic acid or quaternary ammonium function groups and can be successfully immobilised in blended cement systems. The formulation which has been developed is produced from a 9 to 1 blend of ground granulated blast furnace slag (BFS) and ordinary Portland cement (OPC) containing 28% ion exchange resin in the water saturated form. If 6% Microsilica is added to the blended cement the waste loading can be increased to 36 w/o. (author)

  20. 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.

  1. 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.

  2. 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...

  3. 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...

  4. In vitro bioactivity of a tricalcium silicate cement

    International Nuclear Information System (INIS)

    Tricalcium silicate is the major constituent of Portland cement and the responsible for their mechanical strength at early stages. In order to be used as and additive of conventional calcium phosphate cement (CPC), in vitro bioactivity of a calcium silicate cement (CSC) after soaking in simulated body fluid (SBF) for 14 days was study. The cement was obtained by mixing Ca3SiO5, obtained by sol-gel process, and a Na2HPO4 solution. The morphological and structural changes of the material before and after soaking were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed the formation of a layer of a Hydroxyapatite (HA) onto the CSC cement after soaking for 1h in SBF that became denser with the increase of soaking time. The study suggests that Ca3SiO5 would be an effective additive to improve the bioactivity and long term strength of conventional CPC. (author)

  5. 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. PMID:24757414

  6. Influence of Pore Structure on Compressive Strength of Cement Mortar

    Directory of Open Access Journals (Sweden)

    Haitao Zhao

    2014-01-01

    Full Text Available 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.

  7. Effect of coal gangue with different kaolin contents on compressive strength and pore size of blended cement paste

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yimin; Zhou Shuangxi; Zhang Wensheng [China Building Materials Academy, Beijing (China)

    2008-02-15

    The effects of activated coal gangue on compressive strength, porosity and pore size distribution of hardened cement pastes were investigated. Activated coal gangue with two different kaolin contents, one higher and one lower, were used to partially replace Portland cement at 0%, 10%, and 30% by weight. The water to binder ratio of 0.5 was used for all the blended cement paste mixes. Experimental results indicate that the blended cement of activated coal gangue mortar with higher kaolin mineral content has a higher compressive strength than that with lower kaolin mineral content. The porosity and pore size of blended cement mortar were significantly affected by the replacement of activated coal gangue.

  8. 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.

  9. Impact of Nano-Pore Structure in Harden Non-Sintering Cement.

    Science.gov (United States)

    Seo, Seong-Gyu; Kim, Sang-Chai; Kim, Eun-Sik; Mun, Kyoung-Ju; Park, Won-Chun; Eum, Hyun-Mi; Yoon, Hyung-Sun

    2015-07-01

    This study investigates the nano pore structure of non-sintering cement (NSC) matrix. The result of pore structure properties showed no considerable difference in the total pore volume, but presented a large distinction in distribution of pore diameter by cement mixing ratio. The pore-diameter of NSC paste shows that occupation ratio of pore diameter below 10 nm was larger and was smaller than ordinary Portland cement (OPC) and blast-furnace slag cement (BSC) at pore diameter of over 10 nm. The reasons are due to the hydrate such as C-S-H gel and ettringite which formed dense nano pore structure of NSC matrix. PMID:26373159

  10. 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.

  11. 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

  12. Urban carbon dioxide in Portland, Oregon

    Science.gov (United States)

    Bostrom, G. A.; Brooks, M.; Rice, A. L.

    2010-12-01

    Ambient concentrations of atmospheric carbon dioxide (CO2) are reported for the Portland, Oregon (USA) metropolitan region since late July, 2009. Three stationary locations were established: a downtown location on the campus of Portland State University; a residential site in southeast Portland; and a rural station on Sauvie Island, located ~30km northwest of Portland in the Columbia River Gorge. Continuous measurements of CO2 at the sites average 400-410ppm and show considerable variability due to CO2 sources, sinks and meteorological drivers of ventilation. Within this variability, a marked 20-30ppm diurnal cycle is observed due to photosynthetic activity and variations in the planetary boundary layer. In-city CO2 concentrations are on average enhanced by 5-6ppm over the Sauvie Island site during upgorge wind conditions, a difference which is greatest in the afternoon. Measurements of the 13C/12C ratio of CO2 in downtown Portland are significantly depleted in 13C relative to 12C compared with background air and suggest that regional CO2 is dominated by petroleum sources (70-80%). High degrees of relationship between CO2 variability and primary air pollutants CO and NO (r2=0.70 to 0.80), measured by the Oregon Department of Environmental Quality at the Southeast Portland location, corroborate this finding and illustrate the importance of traffic emissions on elevated ambient CO2 concentrations. In addition to CO2 at the fixed sites, measurements of street-level CO2 concentrations were obtained using a mobile instrument mounted in a bike trailer. Results from these field data show relatively homogenous CO2 concentrations throughout residential Portland neighborhoods with significant enhancements in CO2 on busy roadways or near areas of traffic congestion.

  13. 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.

  14. 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...

  15. 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.

  16. Sulfate attack and reinforcement corrosion in concrete with recycled concrete aggregates and supplementary cementing materials

    OpenAIRE

    Corral Higuera, Ramón; Arredondo Rea, Susana Paola; Neri Flores, M.A.; Gómez Soberón, José Manuel Vicente; Almeraya Calderón, F.; Castorena González, J.H.; Almaral Sánchez, Jorge Luis

    2011-01-01

    As strategies to contribute to the concrete industry sustainability, reinforced concrete was fabricated using recycled concrete coarse aggregate and replacing partially portland cement with supplementary cementing materials as fly ash and silica fume. On test specimens, partially immersed in 3.5% Na2SO4 aqueous solution, the effect of the recycled and supplementary materials against sulfate attack and reinforcement corrosion was evaluated. For such aim, weight loss of concrete and corrosion p...

  17. Sustainable production of blended cement in Pakistan through addition of natural pozzolana

    OpenAIRE

    Ahmad Muhammad Imran; Sajjad Muhammad; Khan Irfan Ahmed; Durrani Amina; Durrani Ali Ahmed; Gul Saeed; Ullah Asmat

    2016-01-01

    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 an...

  18. 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.

  19. Polycarboxylate superplasticiser admixtures: effect on hydration, microstructure and rheological behaviour in cement pastes

    OpenAIRE

    Puertas, F.; Santos, H.; Palacios, M.; Martínez-Ramírez, Sagrario

    2005-01-01

    A study was conducted on the effect of a polycarboxylate (PC) admixture on the mechanical, mineralogical, microstructural and rheological behaviour of Portland cement pastes. It was observed that the presence of PC admixture retards the initial cement hydration reactions, although this effect may be offset by possible increased diffusion in later stages. Additionally, the PC admixtures produce a few alterations in the structure and composition of the formed C–S–H gel. The addition of 1% PC...

  20. Properties of Chemically Combusted Calcium Carbide Residue and Its Influence on Cement Properties

    OpenAIRE

    Hongfang Sun; Zishanshan Li; Jing Bai; Shazim Ali Memon; Biqin Dong; Yuan Fang; Weiting Xu; Feng Xing

    2015-01-01

    Calcium carbide residue (CCR) is a waste by-product from acetylene gas production. The main component of CCR is Ca(OH)2, which can react with siliceous materials through pozzolanic reactions, resulting in a product similar to those obtained from the cement hydration process. Thus, it is possible to use CCR as a substitute for Portland cement in concrete. In this research, we synthesized CCR and silica fume through a chemical combustion technique to produce a new reactive cementitious powder (...

  1. Various durability aspects of cement pastes and concretes with supplementary cementitious materials

    OpenAIRE

    SAILLIO, Mickael; BAROGHEL BOUNY, Véronique; PRADELLE, Sylvain

    2016-01-01

    The use of supplementary cementitious materials (SCMs) as a constituent for concrete receives considerable attention, due to the lower CO2 emission of these materials compared to the production of classic Portland cement. Furthermore, concretes incorporating SCMs show some improved durability properties. SCMs are mainly pozzolanic materials (Fly Ash or Metakaolin) or alkali-activated materials such as ground granulated blast slag (GGBS). In this paper, the durability of concretes and cement p...

  2. Corrosion Resistance of Calcium Aluminate Cement Concrete Exposed to a Chloride Environment

    OpenAIRE

    Ki Yong Ann; Chang-Geun Cho

    2014-01-01

    The present study concerns a development of calcium aluminate cement (CAC) concrete to enhance the durability against an externally chemically aggressive environment, in particular, chloride-induced corrosion. To evaluate the inhibition effect and concrete properties, CAC was partially mixed with ordinary Portland cement (OPC), ranging from 5% to 15%, as a binder. As a result, it was found that an increase in the CAC in binder resulted in a dramatic decrease in the setting time of fresh concr...

  3. The incorporation of low and medium level radioactive wastes (solids and liquids) in cement

    International Nuclear Information System (INIS)

    Laboratory studies and mixing plant trials on simulated radioactive waste formulations are reported. Long term stability testing of various formulations including those containing blast furnace slag-ordinary Portland cement, sodium nitrate, ion exchange resins, and sodium nitrate-tributyl phosphate, are reported and some results are given. Mixing plant trials with a high shear cement mixer are reported. An outline of future work is presented. (U.K.)

  4. Seawater leachability of cement solidified heavy metal wastes

    International Nuclear Information System (INIS)

    This paper investigates the seawater leachability of portland cement, solidified cadmium, and lead wastes. The synthetic seawater leachates were analyzed for metals content using atomic absorption spectrophotometry. The pH and alkalinity of the leachate was also measured. The cumulative cadmium release after 46 days of leaching was approximately 1.0 percent of the initial total amount added to the portland cement mixture. The microstructure of the solidified waste was investigated using the SEM, XRD, MIP and helium pycnometry. Cadmium was detected as cadmium hydroxide. During the leaching process the surficial microstructure of the solidified waste exhibited a dynamic layer of calcite, paragonite and brucite while the internal structure showed large amounts of ettringite crystals in the cadmium waste only which caused excessive expansion and cracking. A proposed leaching mechanism experienced by the solidified waste is related to the microstructural characteristics of the matrix

  5. Maintenance of Bacterial Cultures on Anhydrous Silica Gel

    Science.gov (United States)

    Lennox, John E.

    1977-01-01

    Suspensions of 20 different cultures were grown on appropriate media, then pipetted into sterile anhydrous silica gel. Silica gel cultures after incubation and refrigerated storage were tested for viability. Results showed little mutation, low replication, low contamination, minimal expenses, and survival up to two years. (CS)

  6. 21 CFR 184.1845 - Stannous chloride (anhydrous and dihydrated).

    Science.gov (United States)

    2010-04-01

    .... (b) Both forms of the ingredient meet the specifications of the Food Chemicals Codex, 3d Ed. (1981... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Stannous chloride (anhydrous and dihydrated). 184.1845 Section 184.1845 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND...

  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. Encapsulation of ILW raffinate in the Dounreay cementation plant

    International Nuclear Information System (INIS)

    The Dounreay Cementation Plant has been designed and constructed to encapsulate the first cycle liquid raffinate arising from the reprocessing of irradiated Research Reactor fuel into a cementitious matrix. The acidic liquid waste is conditioned with sodium hydroxide prior to mixing with the cement powders (a 9:1 ratio of Blast Furnace Slag / Ordinary Portland Cement with 5% Lime). The complete cement mixing process is performed within the 500-liter drum, which provides the waste package primary containment. The plant has recently been commissioned and has commenced routine operation, processing stocks of existing raffinate that has been stored at Dounreay for up to 30 years. The waste loading per drum has been optimised within the constraints of the chemical composition of the raffinate, with an expected plant throughput of 2.5 m3/week. (author)

  9. The Albedo of Pervious Cement Concrete Linearly Decreases with Porosity

    OpenAIRE

    Rui Zhang; Guosheng Jiang; Jia Liang

    2015-01-01

    Pervious pavements have been advocated as a potential countermeasure to the urban heat island effect. To understand if pervious pavements stay cooler than conventional pavements, the albedo of the pervious concrete must be understood. This study measured the albedo of pervious concrete with different porosity. Four Portland cement concrete mixes were casted, using designed amounts of sand to vary the porosity of the pervious concrete samples. The samples were sliced and the spectral reflectan...

  10. Interface and internal compatibility in a copper fibre cement composite

    OpenAIRE

    Kittl, P.; Martínez, V.

    1993-01-01

    This paper presents the mechanical behaviour of a compacted composite formed by short ductile copper fibres randomly distributed in portland cement matrix. The samples, a half with fibres and the other without them, were subjected to compression fatigue. So, 1 hertz and the value of stress corresponding to the 1% of the probability of fracture by gradual load were used. Diagrams of cumulative probability of fracture against cycles are obtained for both types of samples. Scanning electron micr...

  11. Saw Dust Ash as Partial Replacement for Cement in Concrete

    OpenAIRE

    Raheem, A. A.; Olasunkanmi, B. S.; Folorunso, C. S.

    2012-01-01

    This research considered the use of saw dust ash as a pozzolan in the production of concrete. the study investigated the physical properties and chemical composition of saw dust ash (SDA) as well as the workability, and compressive strength properties of the concrete produced by replacing 5%, 10%, 15%, 20% and 25% by weight of ordinary Portland cement with SDA. Slump and compacting factor tests were carried out on the fresh concrete and compressive strength test on hardened concrete. The conc...

  12. Influence of chloride admixtures on cement matrix durability

    International Nuclear Information System (INIS)

    The influence of various inorganic salts, as chloride admixtures to Portland cement, on the mechanical properties and the durability of the matrix has been studied. The salts used in this study are chromium, nickel and cadmium chlorides. Improved compressive strength values are obtained which have been correlated to the stable metal hydroxide formation in high pH environment. Under static water conditions at 500C, hydrolyzed chloride ions exhibit adverse effects on the matrix durability through rapid release of calcium as calcium chloride in the initial period of leaching. On the contrary, enhanced matrix durability is obtained on long term leaching in the case of cement containing chromium chloride

  13. 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...

  14. Triaxial shear behavior of a cement-treated sandegravel mixture

    Institute of Scientific and Technical Information of China (English)

    Younes Amini; Amir Hamidi

    2014-01-01

    A number of parameters, e.g. cement content, cement type, relative density, and grain size distribution, can influence the mechanical behaviors of cemented soils. In the present study, a series of conventional triaxial compression tests were conducted on a cemented poorly graded sandegravel mixture containing 30%gravel and 70%sand in both consolidated drained and undrained conditions. Portland cement used as the cementing agent was added to the soil at 0%, 1%, 2%, and 3%(dry weight) of sandegravel mixture. Samples were prepared at 70%relative density and tested at confining pressures of 50 kPa, 100 kPa, and 150 kPa. Comparison of the results with other studies on well graded gravely sands indicated more dilation or negative pore pressure in poorly graded samples. Undrained failure envelopes determined using zero Skempton’s pore pressure coefficient ðA ¼ 0Þ criterion were consistent with the drained ones. Energy absorption potential was higher in drained condition than undrained condition, suggesting that more energy was required to induce deformation in cemented soil under drained state. Energy ab-sorption increased with increase in cement content under both drained and undrained conditions.

  15. 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.

  16. Performance assessment of cement-based materials blended with micronized sand: microstructure, durability and sustainability

    NARCIS (Netherlands)

    Wang, Y.

    2013-01-01

    Concrete is one of the most important construction materials in the world. However, Portland cement which is one of the constituents of concrete is responsible for about 5-10% of global CO2 emission. From sustainability point of view, therefore, it is important to search for materials which can be u

  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. Autogenous shrinkage in high-performance cement paste: An evaluation of basic mechanisms

    DEFF Research Database (Denmark)

    Lura, Pietro; Jensen, Ole Mejlhede; van Breugel, Klaas

    2003-01-01

    mechanical and thermodynamical basis. Furthermore, this mechanism is easily applicable in a numerical model when dealing with a continuously changing microstructure. In order to test the numerical model, autogenous deformation and internal relative humidity (RH) of a Portland cement paste were measured...

  19. 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 by a...... valuable knowledge of SCMs, which is relevant for performance based design of concrete structures. In addition, the thesis provides guidelines for porosity investigations with focus on the applicability of the methods and sources of error. Pore structure was here determined by several methods, mercury...... 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, the...

  20. Evaluation of solidified cement waste forms

    International Nuclear Information System (INIS)

    A part of the program of the treatment of low and intermediate-level liquid wastes, is presented. The concrete has been suggested as a encapsulation or overpack material for long-term storage of radioactive waste from the nuclear fuel cycle, particularly in conjunction with the disposal of lowand intermediate-level waste. The influence of sodium nitrates, as a possible integrating component of waste, on some properties of national Portland cement, was investigated. The waste form properties, discussed in terms of their dependency on waste type and amount, include water/cement ratio, setting times, compressive strength and homogeneity. Criteria to be applied in the assessment of the final solidified waste are proposed. (Author)