Portland-pfa cement: a comparison between intergrinding and blending

Energy Technology Data Exchange (ETDEWEB)

Monk, M

1983-09-01

Portland-pfa cements containing 20-40% (by weight) pfa have been prepared in the laboratory both by intergrinding the ashes with clinker and by blending with cement. Cement properties have been assessed according to BS 4550 and scanning electron microscopy was used to examine the effects of grinding upon the pfa particles. The work has shown that intergrinding leads to an improvement in the water-reducing properties of coarse pfas and also in their pozzolanic activity as indicated by compressive strength development at later ages. Setting times have been found to be essentially the same for blended and interground cements, both being considerably longer than for typical ordinary Portland cements. Thus the results of this investigation indicate that, provided pfa's are chemically acceptable, they can be used for Portland-pfa cement manufacture by intergrinding irrespective of their coarseness.

Natural cement as the precursor of Portland cement: Methodology for its identification

International Nuclear Information System (INIS)

Varas, M.J.; Alvarez de Buergo, M.; Fort, R.

2005-01-01

When cements appeared in the 19th century, they took the place of traditional binding materials (lime, gypsum, and hydraulic lime) which had been used until that time. Early cements can be divided into two groups, natural and artificial (Portland) cements. Natural cements were introduced first, but their widespread usage was short-lived as they were quickly replaced by artificial cements (Portland), still the most important and predominant today. The main differences between natural and artificial cements arise during the manufacturing process. The final properties of the cements are greatly influenced by differences in the raw materials and burning temperatures employed. The aim of this paper is to assess the efficiency of traditional analytical techniques (petrographic microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR)) used to differentiate natural and artificial cements

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

Science.gov (United States)

2011-12-08

... and Cement Clinker From Japan Determination On the basis of the record \\1\\ developed in the subject... duty order on gray Portland cement and cement clinker from Japan would be likely to lead to... and Cement Clinker from Japan: Investigation No. 731- TA-461 (Third Review). By order of the...

Mechanism for the stabilization/solidification of arsenic-contaminated soils with Portland cement and cement kiln dust.

Science.gov (United States)

Yoon, In-Ho; Moon, Deok Hyun; Kim, Kyoung-Woong; Lee, Keun-Young; Lee, Ji-Hoon; Kim, Min Gyu

2010-11-01

In this study, the mechanism for the stabilization/solidification (S/S) of arsenic (As)-contaminated soils with Portland cement (PC), and cement kiln dust (CKD) using 1 N HCl extraction fluid, X-ray powder diffraction (XRPD), X-ray absorption near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS) spectroscopy was investigated. The degree of As immobilization after stabilization was assessed using a 1 N HCl extraction on the basis of the Korean Standard Test (KST). After 1 day of curing with 30 wt% PC and 7 days of curing with 50 wt% CKD, the concentration of As leached from the amended soils was less than the Korean countermeasure standard (3 mg L(-1)). The As concentrations in the leachate treated with PC and CKD were significantly decreased at pH > 3, indicating that pH had a prevailing influence on As mobility. XRPD results indicated that calcium arsenite (Ca-As-O) and sodium calcium arsenate hydrate (NaCaAsO(4).7.5H(2)O) were present in the PC- and CKD-treated slurries as the key phases responsible for As(III) and As(V) immobilization, respectively. The XANES spectroscopy confirmed that the As(III) and As(V) oxidation states of the PC and CKD slurry samples were consistent with the speciated forms in the crystals identified by XRPD. EXAFS spectroscopy showed As-Ca bonding in the As(III)-PC and As(III)-CKD slurries. The main mechanism for the immobilization of As-contaminated soils with PC and CKD was strongly associated with the bonding between As(III) or As(V) and Ca. Copyright 2010 Elsevier Ltd. All rights reserved.

Understanding mineral trioxide aggregate/Portland-cement: a review of literature and background factors.

Science.gov (United States)

Steffen, R; van Waes, H

2009-06-01

This was to carry out a review of the literature concerning mineral trioxide aggregate (MTA) and Portland cement with regards to clinical, biological and mechanical findings and a possible substitution of MTA through Portland cement for endodontic use. Electronic literature search of scientific papers from January 1993 to January 2009 was carried out on the MEDLINE and Scopus databases using specific key words. In total, 57 papers were identified that dealt with MTA and Portland cement in a relevant way. The review of 50 papers conforming to the applied criteria showed that MTA and Portland cements have the same clinical, biological and mechanical properties. In animal experiments and technical characterisations both materials seemed to have very similar properties. The only difference is bismuth oxide in MTA added for better radio opacity. It seems likely that MTA materials are based on industrial Portland cements mixed with bismuth oxide. More studies, especially some long-term studies comparing MTA and Portland cement, are necessary. The existing literature gives a solid base for clinical studies with Portland cement in order to replace MTA as an endodontic material. Portland cement could be a substitute for most endodontic materials used in primary teeth.

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

Science.gov (United States)

2011-05-17

... Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants AGENCY... Emission Standards for Hazardous Air Pollutants from the Portland Cement Manufacturing Industry Response to... by the Portland Cement Industry and the New Source Performance Standards for Portland Cement Plants...

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

Science.gov (United States)

2011-01-18

... Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants AGENCY...) from the Portland Cement Manufacturing Industry and Standards of Performance (NSPS) for Portland Cement... Standards for Hazardous Air Pollutant From the Portland Cement Manufacturing Industry Docket, Docket ID No...

Analyses of heavy metals in mineral trioxide aggregate and Portland cement.

Science.gov (United States)

Schembri, Matthew; Peplow, George; Camilleri, Josette

2010-07-01

Portland cement is used in the construction industry as a binder in concrete. It is manufactured from chalk, limestone, and clay, which are clinkered at very high temperatures and ground with gypsum to form Portland cement. The raw materials and the manufacturing process can result in the inclusion of heavy metals in Portland cement. Portland cement with a four to one addition of bismuth oxide is marketed as mineral trioxide aggregate (MTA), which is used mainly as a dental material. Heavy metal inclusion can be of concern because MTA is in contact with hard and soft tissues. Measurements of arsenic, lead, and chromium in hydrated gray and white Portland cement, ProRoot MTA, and MTA Angelus were conducted with graphite furnace atomic absorption spectrophotometry after acid digestion on the hydrated material. The leaching of the metal ions from the solid material in water and simulated body fluid (SBF) was also determined. All cement types showed high relative values of leached chromium compared with arsenic and lead in both the total metal content and leached species. The gray Portland cement showed the highest total amount of metal. The white Portland and both MTAs had lower values for all the leached metal ions. Both MTAs released more arsenic than the amount specified in ISO 9917-1 (2007). Portland cements and MTAs showed evidence of heavy metals in the acid-soluble form as well as leaching in deionized water and SBF. MTA contained levels of arsenic higher than the safe limit specified by the ISO 9917-1 (2007). Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Effect of blended materials on U(VI) retention characteristics for portland cement solidification product

International Nuclear Information System (INIS)

Tan Hongbin; Ma Xiaoling; Li Yuxiang

2006-01-01

Using the simulated groundwater as leaching liquid, the retention capability of U(VI) in solidification products with Portland cement, the Portland cement containing silica fume, the Portland cement containing metakaolin and the Portland cement containing fly ash was researched by leaching experiments at 25 degree C for 42 d. The results indicate silica fume and metakaolin as blended materials can improve the U(VI) retention capability of Portland cement solidification product, but fly ash can not. (authors)

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

Science.gov (United States)

2011-08-12

... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-461 (Third Review)] Gray Portland Cement and Cement Clinker From Japan; Scheduling of an Expedited Five-Year Review Concerning the Antidumping Duty Order on Gray Portland Cement and Cement Clinker From Japan AGENCY: United States International...

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

Science.gov (United States)

2012-08-03

...-AQ93 National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing... Portland Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants,'' which was... Manufacturing Industry and Standards of Performance for Portland Cement Plants'' under Docket ID No. EPA-HQ-OAR...

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.

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

Science.gov (United States)

Bodanezi, Augusto; Carvalho, Nara; Silva, Daniela; Bernardineli, Norberti; Bramante, Clovis Monteiro; Garcia, Roberto Brandão; de Moraes, Ivaldo Gomes

2008-01-01

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).

Mechanism and Modelling for Sorption of Toxic Ion on Cement Kiln Dust

International Nuclear Information System (INIS)

EI- Dakroury, A.; Sayed, M.S.; EL- Sherif, E.

2009-01-01

Cement manufacturing is a critically important industry in Egypt. These industrial by-product and waste materials must be managed responsibly to insure a clean and safe environment. Cement kiln dust (CKD) is a significant by-product material of the cement manufacturing process. Cement kiln dust is a waste residue composed chiefly of oxidized, anhydrous, micron - sized particles generated as a by product of the manufacture of Portland cement. The use of cement kiln dust as adsorbent in wastewater treatment has a great attention as cheap material and clay structure. This work will discuss the basic characteristics of CKD physical and chemical properties and regulatory requirements: The batch removal of Cr(VI) from aqueous solution using low cost adsorbents such as cement kiln dust under different experimental conditions. The influences of initial Cr (VI) ion concentration (20 to 300 mg1-1) and ph (1 to 4) were investigated in this study. Adsorption of Cr (VI) is highly ph-dependent and the results indicate that the optimum ph for the removal was found to be 1 for CKD. A comparison of kinetic models applied to the adsorption of Cr (VI) ions on the CKD was evaluated for the pseudo first order, the pseudo second-order, Elovich and intra particle diffusion kinetic models, respectively. The results showed that the pseudo second-order kinetic model was found to correlate the experimental data well

Electrically conductive Portland cement concrete.

Science.gov (United States)

1986-01-01

There is a need for an effective, simple-to-install secondary anode system for use in the cathodic protection of reinforced concrete bridge decks. In pursuit of such a system, carbon fibers and carbon black were incorporated in portland cement concre...

Alternatieven voor Portland Cement in ontwikkelingslanden onderzocht : continue-kalkoven maakt toepassing van kalk pozzolaan cement mogelijk

NARCIS (Netherlands)

Egmond - de Wilde De Ligny, van E.L.C.; Jongsma, Ivo

1995-01-01

In de discussie over bouwmaterialen in ontwikkelingslanden wordt vaak gepleit voor alternatieven voor Portland Cement. De productie van Portland Cement is kapitaal- en energie-intensief en draagt weinig bij aan de ontwikkeling van deze landen. De klein schaliger productie van alternatieven voor

Characterization and chemical activity of Portland cement and two experimental cements with potential for use in dentistry.

Science.gov (United States)

Camilleri, J

2008-09-01

To evaluate the chemical activity of Portland cement and two other cement types with similar chemical composition to mineral trioxide aggregate with the aim of developing these cements for further applications in dentistry. The chemical composition of the three cement types namely Portland cement, calcium sulpho-aluminate cement and calcium fluoro-aluminate cement was evaluated by elemental analysis using energy dispersive analysis with X-ray under the scanning electron microscope and by X-ray diffraction analysis (XRD) to determine the phases. The constituents of the hydration reaction by-products were evaluated by XRD analysis of the set cements at 1, 7, 28 and 56 days and by analysis of the leachate by ion chromatography. The pH of both cements and leachate was determined at different time intervals. Cements admixed with micro-silica were also tested to determine the effect of micro-silica on the reaction by-products. All three cement types were composed of tricalcium silicate as the main constituent phase. The hydration reaction of Portland cement produced calcium hydroxide. However, this was not present in the other cements tested at all ages. Admixed micro-silica had little or no effect on the cements with regard to reaction by-products. The pH of all cements tested was alkaline. Both the experimental calcium sulpho-aluminate cement and calcium fluoro-aluminate cement had different hydration reactions to that of Portland cement even though calcium silicate was the major constituent element of both cement types. No calcium hydroxide was produced as a by-product to cement hydration. Micro-silica addition to the cement had no effect on the hydration reaction.

Parameters of Alumina Cement and Portland Cement with Addition of Chalcedonite Meal

Science.gov (United States)

Kotwa, Anna

2017-10-01

Aluminous cement is a quick binder with special properties. It is used primarily to make non-standard monolithic components exposed to high temperatures, + 1300°C. It is also a component of adhesives and mortars. It has a very short setting time. It is characterized by rapid increase in mechanical strength and resistance to aggressive sulphates. It can be used in reinforced concrete structures. Laying of concrete, construction mortar made of alumina cement can be carried out even at temperatures of -10°C. This article discusses a comparison of the parameters of hardened mortar made of alumina cement GÓRKAL 40 and Portland cement CEM I 42.5R. The mortars contain an addition of chalcedonite meal with pozzolanic properties, with particle size of less than 0.063μm. The meal was added in amounts of 5% and 20% of cement weight. Chalcedonite meal used in the laboratory research is waste material, resulting from chalcedonite aggregate mining. It has the same properties as the rock from which it originates. We have compared the parameters of hardened mortar i.e. compressive strength, water absorption and capillarity. The addition of 20% chalcedonite meal to mortars made from aluminous cement will decrease durability by 6.1% relative to aluminous cement mortar without addition of meal. Considering the results obtained during the absorbency tests, it can be stated that the addition of chalcedonite meal reduces weight gains in mortars made with cement CEM I 42.5 R and alumina cement. Use of alumina cement without addition of meal in mortars causes an increase of mass by 248% compared to Portland cement mortars without additions, in the absorption tests. The addition of chalcedonite meal did not cause increased weight gain in the capillary action tests. For the alumina cement mortars, a lesser weight gains of 24.7% was reported, compared to the Portland cement mortar after 28 days of maturing.

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

Science.gov (United States)

2011-01-18

... Cement Manufacturing Industry and Standards of Performance for Portland Cement Plants AGENCY... Portland Cement Manufacturing Industry Docket, Docket ID No. EPA-HQ-OAR-2002-0051, 1200 Pennsylvania Ave... Portland Cement Manufacturing Industry Docket, EPA West, Room 3334, 1301 Constitution Ave., NW., Washington...

Production of portland cement using Moroccan oil shale and comparative study between conventional cement plant and cement plant using oil shale

International Nuclear Information System (INIS)

Doumbouya, M.; Kacemi, K.E.; Kitane, S.

2012-01-01

Like the use of coal ash from power plants as an addition to cement, oil shale are used for cement production on an industrial scale in Estonia, China, USA and Germany. Oil shale can be utilized in manufacturing the cement. In addition to the utilization of these by-products after combustion, it can also reduce the required temperature for the clinkering reactions during the production of Portland clinker. We performed a study on the Moroccan oil shale to maximize the use of oil shale ash in the manufacturing of Portland cement. We found that Moroccan oil shale ash can be used up to 30% with 70% Portland clinker without altering its principle properties. The corresponding temperature required to generate the required liquid for the clinkering reactions as well as the essential ingredients for clinker was found to be around 850 to 1000 deg. C. The operating temperatures for this optimized blend ratio were found to 1000 deg. C. The resulting Portland clinker from this ratio will need further testing in accordance with international standards for Portland cement to examine properties like strength and setting time. (author)

Portland cement versus MTA as a root-end filling material. A pilot study.

Science.gov (United States)

da Silva, Sérgio Ribeiro; da Silva Neto, José Dias; Veiga, Daniela Francescato; Schnaider, Taylor Brandão; Ferreira, Lydia Masako

2015-02-01

To assess periradicular lesions clinically and by computed tomography (CT) after endodontic surgery using either Portland cement or mineral trioxide aggregate (MTA) as a root-end filling material. Three patients diagnosed with periradicular lesions by cone-beam CT underwent endodontic surgery with root-end filling. Patient A was treated with MTA as the root-end filling material, patient B was treated with Portland cement and patient C had two teeth treated, one with MTA and the other with Portland cement. Six months after surgery, the patients were assessed clinically and by CT scan and the obtained results were compared. Periradicular tissue regeneration was observed in all cases, with no significant differences in bone formation when comparing the use of MTA and Portland cement as root-end filling materials. Both mineral trioxide aggregate and Portland cement were successful in the treatment of periradicular lesions.

Chemical composition, radiopacity, and biocompatibility of Portland cement with bismuth oxide.

Science.gov (United States)

Hwang, Yun-Chan; Lee, Song-Hee; Hwang, In-Nam; Kang, In-Chol; Kim, Min-Seok; Kim, Sun-Hun; Son, Ho-Hyun; Oh, Won-Mann

2009-03-01

This study compared the chemical constitution, radiopacity, and biocompatibility of Portland cement containing bismuth oxide (experimental cement) with those of Portland cement and mineral trioxide aggregate (MTA). The chemical constitution of materials was determined by scanning electron microscopy and energy-dispersive X-ray analysis. The radiopacity of the materials was determined using the ISO/6876 method. The biocompatibility of the materials was tested by MTT assay and tissue reaction. The constitution of all materials was similar. However, the Portland cement and experimental cement were more irregular and had a larger particle size than MTA. The radiopacity of the experimental cement was similar to MTA. The MTT assay revealed MTA to have slightly higher cell viability than the other materials. However, there were no statistically significant differences between the materials, with the exception of MTA at 24 h. There was no significant difference in the tissue reaction between the experimental groups. These results suggest that the experimental cement may be used as a substitute for MTA.

Biocompatibility of Portland cement combined with different radiopacifying agents.

Science.gov (United States)

Lourenço Neto, Natalino; Marques, Nádia C T; Fernandes, Ana Paula; Rodini, Camila O; Duarte, Marco A H; Lima, Marta C; Machado, Maria A A M; Abdo, Ruy C C; Oliveira, Thais M

2014-03-01

The aim of this study was to evaluate the response of rat subcutaneous tissue to Portland cement combined with two different radiopacifying agents, iodoform (CHI3) and zirconium oxide (ZrO2). These materials were placed in polyethylene tubes and implanted into the dorsal connective tissue of Wistar rats for 7 and 15 days. The specimens were then stained with hematoxylin and eosin, and inflammatory reaction parameters were evaluated by light microscopy. The intensity of the inflammatory response to the sealants was analyzed by two blind calibrated observers throughout the experimental period. Histological analysis showed that all the materials caused a moderated inflammatory reaction at 7 days, which then diminished with time. At 15 days, the inflammatory reaction was almost absent, and fibroblasts and collagen fibers were observed indicating normal tissue healing. The degrees of the inflammatory reaction on different days throughout the experimental period were compared using the non-parametric Kruskal-Wallis test. Statistical analysis demonstrated no significant differences amongst the groups, and Portland cement associated with radiopacifying agents gave satisfactory results. Therefore, Portland cement used in combination with radiopacifying agents can be considered a biocompatible material. Although our results are very encouraging, further studies are needed in order to establish safe clinical indications for Portland cement combined with radiopacifying agents.

Assessment of Pollution Potentialities of some Portland Cement ...

African Journals Online (AJOL)

Chemical analysis of some Portland cement commonly used in Nigeria was carried out. All the cement studies were found to be good for concrete work especially where no special property is required. The concentration levels of heavy metals in all the cement samples were above the tolerance limit and therefore need to ...

Influence of ultrasonic radiation on the amorphous zeolite - Portland cement system

NARCIS (Netherlands)

Jakevicius, L.; Vaiciukyniene, D.; Demcenko, A.

2012-01-01

This paper considers the investigation of influence of an amorphous synthetic zeolite with inserted $Ca^{2+}$ ions additive (ASZ) on the hydration temperature of Portland cement paste. In this investigation the sonicated Portland cement paste is compared to the non-sonicated paste; and then the

Binding of chloride and alkalis in Portland cement systems

International Nuclear Information System (INIS)

Nielsen, Erik P.; Herfort, Duncan; Geiker, Mette R.

2005-01-01

A thermodynamic model for describing the binding of chloride and alkalis in hydrated Portland cement pastes has been developed. The model is based on the phase rule, which for cement pastes in aggressive marine environment predicts multivariant conditions, even at constant temperature and pressure. The effect of the chloride and alkalis has been quantified by experiments on cement pastes prepared from white Portland cements containing 4% and 12% C 3 A, and a grey Portland cement containing 7% C 3 A. One weight percent calcite was added to all cements. The pastes prepared at w/s ratio of 0.70 were stored in solutions of different Cl (CaCl 2 ) and Na (NaOH) concentrations. When equilibrium was reached, the mineralogy of the pastes was investigated by EDS analysis on the SEM. A well-defined distribution of chloride was found between the pore solution, the C-S-H phase, and an AFm solid solution phase consisting of Friedel's salt and monocarbonate. Partition coefficients varied as a function of iron and alkali contents. The lower content of alkalis in WPC results in higher chloride contents in the C-S-H phase. High alkali contents result in higher chloride concentrations in the pore solution

Portland cement hydration and early setting of cement stone intended for efficient paving materials

Science.gov (United States)

Grishina, A.

2017-10-01

Due to the growth of load on automotive roads, modern transportation engineering is in need of efficient paving materials. Runways and most advanced highways require Portland cement concretes. This makes important the studies directed to improvement of binders for such concretes. In the present work some peculiarities of the process of Portland cement hydration and early setting of cement stone with barium hydrosilicate sol were examined. It was found that the admixture of said sol leads to a shift in the induction period to later times without significant change in its duration. The admixture of a modifier with nanoscale barium hydrosilicates increases the degree of hydration of the cement clinker minerals and changes the phase composition of the hydration products; in particular, the content of portlandite and tricalcium silicate decreases, while the amount of ettringite increases. Changes in the hydration processes of Portland cement and early setting of cement stone that are caused by the nanoscale barium hydrosilicates, allow to forecast positive technological effects both at the stage of manufacturing and at the stage of operation. In particular, the formwork age can be reduced, turnover of molds can be increased, formation of secondary ettringite and corrosion of the first type can be eliminated.

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

Science.gov (United States)

2012-07-18

... and 63 National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing... Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing Industry and Standards of... manufacturing plants. Federal government Not affected. State/local/tribal government.... Portland cement...

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

International Nuclear Information System (INIS)

Jaitanong, N.; Zeng, H.R.; Li, G.R.; Yin, Q.R.; Vittayakorn, W.C.; Yimnirun, R.; Chaipanich, A.

2010-01-01

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.

Recycled materials in Portland cement concrete

Science.gov (United States)

2000-06-01

This report pertains to a comprehensive study involving the use of recycled materials in Portland cement concrete. Three different materials were studied including crushed glass (CG), street sweepings (SS), and recycled concrete (RC). Blast furnace s...

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

Science.gov (United States)

2010-09-09

... Hazardous Air Pollutants From the Portland Cement Manufacturing Industry and Standards of Performance for... Standards for Hazardous Air Pollutants From the Portland Cement Manufacturing Industry and Standards of... (NESHAP) from the Portland Cement Manufacturing Industry and to the New Source Performance Standards (NSPS...

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.

Hospital waste ashes in Portland cement mortars

International Nuclear Information System (INIS)

Genazzini, C.; Zerbino, R.; Ronco, A.; Batic, O.; Giaccio, G.

2003-01-01

Nowadays, most concretes incorporate mineral additions such as pozzolans, fly ash, silica fume, blast furnace slag, and calcareous filler among others. Although the technological and economical benefits were the main reasons for the use of mineral additions, the prevention of environmental contamination by means of proper waste disposal becomes a priority. The chance of incorporating hospital waste ashes in Portland cement-based materials is presented here. Ash characterization was performed by chemical analysis, X-ray diffraction, radioactive material detection, and fineness and density tests. Conduction calorimetry and setting time tests were developed on pastes including ash contents from 0% to 100%. Mortars were prepared including ash contents up to 50% of cement. The results of setting time, temperature development, flexural and compressive strengths, water absorption, density, and leachability are analyzed. Results indicate that Portland cement systems could become an alternative for the disposal of this type of ashes

Stabilization of marly soils with portland cement

Science.gov (United States)

Piskunov, Maksim; Karzin, Evgeny; Lukina, Valentina; Lukinov, Vitaly; Kholkin, Anatolii

2017-10-01

Stabilization of marlous soils with Portland cement will increase the service life of motor roads in areas where marl is used as a local road construction material. The result of the conducted research is the conclusion about the principal possibility of stabilization of marlous soils with Portland cement, and about the optimal percentage of the mineral part and the binding agent. When planning the experiment, a simplex-lattice plan was implemented, which makes it possible to obtain a mathematical model for changing the properties of a material in the form of polynomials of incomplete third order. Brands were determined for compressive strength according to GOST 23558-94 and variants of stabilized soils were proposed for road construction.

Improvement of poor subgrade soils using cement kiln dust

Directory of Open Access Journals (Sweden)

Ahmed Mancy Mosa

2017-12-01

Full Text Available Construction of pavements layers on subgrade with excellent to good properties reduces the thickness of the layers and consequently reduces the initial and maintenance cost of highways and vice versa. However, construction of pavements on poor subgrade is unavoidable due to several constrains. Improvement of subgrade properties using traditional additives such as lime and Portland cement adds supplementary costs. Therefore, using by-products in this domain involves technical, economic, and environmental advantages. Cement kiln dust (CKD is generated in huge quantities as a by-product material in Portland cement plants. Therefore, it can be considered as an excellent alternative in this domain. In Iraq, Portland cement plants generate about 350000 tons of CKD annually which is available for free. Therefore, Iraq can be adopted as a case study. This paper covers using CKD to improve the properties of poor subgrade soils based on series of California Bearing Ration (CBR tests on sets of untreated samples and samples treated with different doses of CKD in combination with different curing periods to investigate their effects on soil properties. The results exhibited that adding 20% of CKD with curing for 14 days increases the CBR value from 3.4% for untreated soil to 48% for treated soil; it, also, decreases the swelling ratio. To determine the effects of using this dose under the mentioned curing period on the designed thicknesses of pavements layers, a case study was adopted. The case study results exhibited that treatment of the subgrade soil by 20% of CKD with curing for 14 days reduces the cost of the pavements by $25.875 per square meter.

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

Science.gov (United States)

2011-12-16

... DEPARTMENT OF COMMERCE International Trade Administration [A-588-815] Gray Portland Cement and... Department) initiated the third sunset review of the antidumping duty order on gray portland cement and... of the antidumping duty order on gray portland cement and clinker from Japan would likely lead to...

Silica fume effect on retention characteristics of portland cement for uranium (VI)

International Nuclear Information System (INIS)

Tan Hongbin; Ma Xiaoling; Li Yuxiang

2005-01-01

With simulated groundwater as leachant, the retention capabilities of the portland cement, which contains different amount of silica fume, are investigated under 25 degree C and 42 days. The results indicate that silica fume can improve the retention capabilities of portland cement for uranium. When the cement contains 15% silica fume, the diffusion coefficient is 7 x 10 -3 cm 3 · -1 . It is only 5.5% of the cement without containing fume. (authors)

Portland cement concrete air content study.

Science.gov (United States)

1987-04-20

This study took the analysis of Portland cement concrete air content. Based on the information gathered, this study hold the results were : 1) air-entrained concrete was more durable than non-air entrained concrete all other factors being equal; 2) A...

Dust exposure and the risk of cancer in cement industry workers in Korea.

Science.gov (United States)

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

2013-03-01

Cement is used widely in the construction industry, though it contains hazardous chemicals such as hexavalent chromium. Several epidemiological studies have examined the association between cement dust exposure and cancer, but these associations have proved inconclusive. In the present study, we examined the association between dust exposure and cancer in cement industry workers in Korea. Our cohort consisted of 1,324 men who worked at two Portland cement manufacturing factories between 1997 and 2005. We calculated cumulative dust exposures, then categorized workers into high and low dust exposure groups. Cancer cases were identified between 1997 and 2005 by linking with the national cancer registry. Standardized incidence ratios (SIRs) were calculated for all workers and the high and low dust exposure groups, respectively. The SIR for overall cancers in all workers was increased (1.35, 95% CI: 1.01-1.78). The SIR for stomach cancer in the high dust exposure group was increased (2.18, 95% CI: 1.19-3.65), but there was no increased stomach cancer risk in the low dust exposure group. The SIR for rectal cancer in all workers was increased (3.05, 95% CI: 1.32-6.02). Rectal cancer risk was similar in the high and low exposure groups. Our findings suggest a potential association between exposure in the cement industry and an increased risk of stomach and rectal cancers. However, due to the small number of cases, this association should be further investigated in a study with a longer follow-up period and adjustment for confounders. Copyright © 2012 Wiley Periodicals, Inc.

Mineral trioxide aggregate and Portland cement promote biomineralization in vivo.

Science.gov (United States)

Dreger, Luonothar Antunes Schmitt; Felippe, Wilson Tadeu; Reyes-Carmona, Jessie Fabiola; Felippe, Gabriela Santos; Bortoluzzi, Eduardo Antunes; Felippe, Mara Cristina Santos

2012-03-01

Mineral trioxide aggregate (MTA) and Portland cement have been shown to be bioactive because of their ability to produce biologically compatible carbonated apatite. This study analyzed the interaction of MTA and white Portland cement with dentin in vivo. Seventy-two human dentin tubes were filled with MTA Branco, MTA BIO, and white Portland cement + 20% bismuth oxide (PC1) or PC1 + 10% of calcium chloride (PC2) and implanted subcutaneously in 18 rats at 4 sites from the dorsal area. Empty dentin tubes, implanted in rats of a pilot study, were used as control. After 30, 60, and 90 days, the animals were killed, and the dentin tubes were retrieved for scanning electron microscope analysis. In the periods of 30 and 60 days, the mineral deposition in the material-dentin interface (interfacial layer) and in the interior of dentinal tubules was detected in more tubes filled with MTA Branco and MTA BIO than in tubes filled with PC1 and PC2. After 90 days, the interfacial layer and intratubular mineralization were detected in all tubes except for 3 and 1 of the tubes filled with PC2, respectively. It was concluded that all the cements tested were bioactive. The cements released some of their components in the tissue capable of stimulating mineral deposition in the cement-dentin interface and in the interior of the dentinal tubules. MTA BIO and MTA Branco were more effective in promoting the biomineralization process than Portland cements, mainly after 30 and 60 days. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Effect of mineral trioxide aggregates and Portland cements on inflammatory cells.

Science.gov (United States)

Shahi, Shahriar; Rahimi, Saeed; Yavari, Hamid Reza; Mokhtari, Hadi; Roshangar, Leila; Abasi, Mehran Mesgary; Sattari, Sahar; Abdolrahimi, Majid

2010-05-01

Recently, some studies have compared mineral trioxide aggregate (MTA) with Portland cements, concluding that the principal ingredients of Portland cements are similar to those of MTA. The purpose of the present study was to evaluate the effect of gray MTA, white MTA, and gray and white Portland cements on inflammatory cells in rats. Fresh mixtures mixed with distilled water were placed in polyethylene tubes, which were implanted in the dorsal subcutaneous connective tissue of 60 Sprague-Dawley rats along with empty tubes as controls. Tissue specimens were collected after the rats were sacrificed after 7, 15, 30, 60, and 90 days. The specimens were fixed, stained, processed, and histologically evaluated under a light microscope. Inflammatory reactions were classified as grade 0: without inflammatory cells, grade I: sporadic infiltration of inflammatory cells, grade II: moderate infiltration (125 cells). Data were analyzed with the nonparametric (two factor) analysis of variance and Kruskal-Wallis H-test. All the groups showed grade III inflammation after 7 and 15 days; there was a decrease in the inflammatory process after 30, 60, and 90 days. After 90 days, gray MTA, white MTA, and control groups had grade 0 inflammatory process, but gray Portland cement and white Portland cement groups showed grade 0 to grade I inflammatory processes. MTAs were more biocompatible; however, more studies are required. Copyright (c) 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Health hazards of cement dust

International Nuclear Information System (INIS)

Meo, Sultan A.

2004-01-01

ven in the 21st century, millions of people are working daily in a dusty environment. They are exposed to different types of health hazards such as fume, gases and dust, which are risk factors in developing occupational disease. Cement industry is involved in the development of structure of this advanced and modern world but generates dust during its production. Cement dust causes lung function impairment, chronic obstructive lung disease, restrictive lung disease, pneumoconiosis and carcinoma of the lungs, stomach and colon. Other studies have shown that cement dust may enter into the systemic circulation and thereby reach the essentially all the organs of body and affects the different tissues including heart, liver, spleen, bone, muscles and hairs and ultimately affecting their micro-structure and physiological performance. Most of the studies have been previously attempted to evaluate the effects of cement dust exposure on the basis of spirometry or radiology, or both. However, collective effort describing the general effects of cement dust on different organ and systems in humans or animals, or both has not been published. Therefore, the aim of this review is to gather the potential toxic effects of cement dust and to minimize the health risks in cement mill workers by providing them with information regarding the hazards of cement dust. (author)

Evaluation of the strength and radiopacity of Portland cement with varying additions of bismuth oxide.

Science.gov (United States)

Saliba, E; Abbassi-Ghadi, S; Vowles, R; Camilleri, J; Hooper, S; Camilleri, J

2009-04-01

To study the effect of addition of various proportions of bismuth oxide on compressive strength and radiopacity of Portland cement. The compressive strength of white Portland cement and cement replaced with 10, 15, 20, 25 and 30% bismuth oxide was evaluated by testing cylinders 6 mm in diameter and 12 mm high. Twelve cylinders were tested for each material under study. The radiopacity of the cements tested was evaluated using an aluminium step-wedge and densitometer. The optical density was compared with the relevant thickness of aluminium (Al). Statistical analysis was performed using Analysis of Variance (ANOVA) with P = 0.05 and Tukey test to perform multiple comparison tests. Various additions of bismuth oxide had no significant effect on the strength of the material when compared with the unmodified Portland cement (P > 0.05). The radiopacity of the cements tested ranged from 2.02 mm Al for Portland cement to 9.79 mm Al for the highest bismuth replacement. Addition of bismuth oxide did not affect the compressive strength of Portland cement. All the bismuth oxide cement mixtures had radio-opacities higher than 3 mm thickness of aluminium.

The existence state of uranium(VI) in portland cement matrix material immobilization body

International Nuclear Information System (INIS)

Tan Hongbin; Li Yuxiang

2005-01-01

The basis of Portland cement material reaction with uranium, the corrosion of uranium minerals in nature and the state of study on immobilization of uranium by Portland cement matrix material are introduced, and some considerations are presented. (authors)

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

International Nuclear Information System (INIS)

Torkittikul, Pincha; Chaipanich, Arnon

2012-01-01

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%CaCl 2 exhibited the best bioactivity. - Highlights: ► Optimization CaCl 2 content on the bioactivity and mechanical properties. ► CaCl 2 was used as an addition at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10% by weight. ► CaCl 2 resulted in a decrease in setting time and an increase in early strength. ► Addition of 3%CaCl 2 exhibited the optimum formation of hydroxyapatite.

Structure investigations on Portland cement paste by small angle neutron scattering

International Nuclear Information System (INIS)

Dragolici, C.A.; Lin, A.

2004-01-01

Hydrated Portland cement is a very complex material. Cement paste consists of many crystalline and non-crystalline phases in various ranges of sizes (μm and nm scale). The crystalline phases are embedded in amorphous phases of hydration products. We investigated the structural changes of hydrating phases in a time interval up to 18 days, at Budapest Neutron Center's SANS spectrometer. The small angle neutron scattering of Portland cements prepared with a various water-to-cement ratios, gave us information about the microstructure changes in the material. Fractals were a suitable way for structure modelling. Some comments regarding the opportunity of using the most common models are pointed out. (authors)

Exploratory characterization of volcanic ash sourced from Uganda as a pozzolanic material in portland cement concrete

NARCIS (Netherlands)

Buregyeya, A.; Quercia Bianchi, G.; Spiesz, P.R.; Florea, M.V.A.; Nassingwa, R.; Uzoegbo, H.C.; Schmidt, W.

2013-01-01

The need for alternative cementing materials to ordinary Portland cement (OPC) has promoted characterization research on pozzolana as an important ingredient in cement production. In Uganda, natural pozzolana application in cement production is done by only two producers of Portland cement and at a

Formula of Moulding Sand, Bentonite and Portland Cement toImprove The Quality of Al-Si Cast Alloy

OpenAIRE

Andoko Andoko; Poppy Puspitasari; Avita Ayu Permanasari; Didin Zakaria Lubis

2017-01-01

A binder is any material used to strengthen the bonding of moulding sand grains. The primary function of the binder is to hold the moulding sand and other materialstogether to produce high-quality casts. In this study, there were four binder compositions being tested, i.e. 5% bentonite + 5% Portland cement, 4% bentonite + 6% Portland cement, 6% bentonite + 4% Portland cement, and 7% bentonite + 3% Portland cement. Each specimen was measured for its compressive strength, shear strength, tensil...

Structure investigations on Portland cement paste by small angle neutron scattering

International Nuclear Information System (INIS)

Dragolici, C. A.; Len, A.

2003-01-01

Portland cement pastes consist of many crystalline and non-crystalline phases in various ranges of sizes (nm and mm scale). The crystalline phases are embedded in amorphous phases of the hydration products. We investigated the structural changes of hydrating phases in the time interval of 1-30 days at Budapest Neutron Center's SANS diffractometer. The small angle neutron scattering of Portland cements prepared with a water-to-cement ratio from 0,3 to 0,8 gave us information about the microstructure changes in the material. Fractals were a suitable way for structure modelling. The variation of fractals size depending on the preparation-to-measurement time interval and water-to-cement ratio could be observed. (authors)

Influence of limestone on the hydration of Portland cements

International Nuclear Information System (INIS)

Lothenbach, Barbara; Le Saout, Gwenn; Gallucci, Emmanuel; Scrivener, Karen

2008-01-01

The influence of the presence of limestone on the hydration of Portland cement was investigated. Blending of Portland cement with limestone was found to influence the hydrate assemblage of the hydrated cement. Thermodynamic calculations as well as experimental observations indicated that in the presence of limestone, monocarbonate instead of monosulfate was stable. Thermodynamic modelling showed that the stabilisation of monocarbonate in the presence of limestone indirectly stabilised ettringite leading to a corresponding increase of the total volume of the hydrate phase and a decrease of porosity. The measured difference in porosity between the 'limestone-free' cement, which contained less than 0.3% CO 2 , and a cement containing 4% limestone, however, was much smaller than calculated. Coupling of thermodynamic modelling with a set of kinetic equations which described the dissolution of the clinker, predicted quantitatively the amount of hydrates. The quantities of ettringite, portlandite and amorphous phase as determined by TGA and XRD agreed well with the calculated amounts of these phases after different periods of time. The findings in this paper show that changes in the bulk composition of hydrating cements can be followed by coupled thermodynamic models. Comparison between experimental and modelled data helps to understand in more detail the dominating processes during cement hydration

Comparative study of the properties of ordinary portland cement ...

African Journals Online (AJOL)

The study explored metakaolin as alternative material to cement. It compares the properties of Ordinary Portland Cement (OPC) concrete and binary concrete containing metakaolin as partial replacement of OPC. Two set of concrete samples; one with 10% Metakaolin (MK) replacing OPC by weight, and the other without ...

Hydration characteristics of zirconium oxide replaced Portland cement for use as a root-end filling material.

Science.gov (United States)

Camilleri, J; Cutajar, A; Mallia, B

2011-08-01

Zirconium oxide can be added to dental materials rendering them sufficiently radiopaque. It can thus be used to replace the bismuth oxide in mineral trioxide aggregate (MTA). Replacement of Portland cement with 30% zirconium oxide mixed at a water/cement ratio of 0.3 resulted in a material with adequate physical properties. This study aimed at investigating the microstructure, pH and leaching in physiological solution of Portland cement replaced zirconium oxide at either water-powder or water-cement ratios of 0.3 for use as a root-end filling material. The hydration characteristics of the materials which exhibited optimal behavior were evaluated. Portland cement replaced by zirconium oxide in varying amounts ranging from 0 to 50% in increments of 10 was prepared and divided into two sets. One set was prepared at a constant water/cement ratio while the other set at a constant water/powder ratio of 0.3. Portland cement and MTA were used as controls. The materials were analyzed under the scanning electron microscope (SEM) and the hydration products were determined. X-ray energy dispersive analysis (EDX) was used to analyze the elemental composition of the hydration products. The pH and the amount of leachate in Hank's balanced salt solution (HBSS) were evaluated. A material that had optimal properties that satisfied set criteria and could replace MTA was selected. The microstructure of the prototype material and Portland cement used as a control was assessed after 30 days using SEM and atomic ratio diagrams of Al/Ca versus Si/Ca and S/Ca versus Al/Ca were plotted. The hydration products of Portland cement replaced with 30% zirconium oxide mixed at water/cement ratio of 0.3 were calcium silicate hydrate, calcium hydroxide and minimal amounts of ettringite and monosulphate. The calcium hydroxide leached in HBSS solution resulted in an increase in the pH value. The zirconium oxide acted as inert filler and exhibited no reaction with the hydration by-products of Portland

Hydration kinetics modeling of Portland cement considering the effects of curing temperature and applied pressure

International Nuclear Information System (INIS)

Lin Feng; Meyer, Christian

2009-01-01

A hydration kinetics model for Portland cement is formulated based on thermodynamics of multiphase porous media. The mechanism of cement hydration is discussed based on literature review. The model is then developed considering the effects of chemical composition and fineness of cement, water-cement ratio, curing temperature and applied pressure. The ultimate degree of hydration of Portland cement is also analyzed and a corresponding formula is established. The model is calibrated against the experimental data for eight different Portland cements. Simple relations between the model parameters and cement composition are obtained and used to predict hydration kinetics. The model is used to reproduce experimental results on hydration kinetics, adiabatic temperature rise, and chemical shrinkage of different cement pastes. The comparisons between the model reproductions and the different experimental results demonstrate the applicability of the proposed model, especially for cement hydration at elevated temperature and high pressure.

Physicochemical Properties of MTA and Portland Cement after Addition of Aloe Vera.

Science.gov (United States)

Henrique Borges, Alvaro; Aguirre Guedes, Orlando; Evaristo Ricci Volpato, Luiz; Siebert Filho, Gilberto; Meireles Borba, Alexandre; Zina, Omar; Piva, Evandro; Estrela, Carlos

2017-01-01

The aim of this in vitro study was to determine the liquid-powder ratio, setting time, solubility, dimensional change, pH, and radiopacity of white structural and non-structural Portland cement, ProRoot MTA and MTA Bio, associated with a 2% glycolic solution containing Aloe Vera, as vehicle. Five samples of each material were used for each test, according to the American National Standards Institute/American Dental Association (ANSI/ADA) specification No. 57. Statistical analyses were performed using ANOVA and Tukey's test at 5% significance. When sample distribution was not normal, non-parametric analysis of variance and the Kruskal-Wallis test were used ( α =0.05). No statistical differences were found in liquid-powder ratios among the tested materials. ProRoot MTA showed the longest setting time. Dimensional change values were acceptable in all groups. Also, no significant differences were found in pH values and pH was alkaline in all samples throughout the experiment. Mean radiopacity results obtained for white Portland cements did not meet ANSI/ADA requirements, and were significantly lower than those obtained for MTA-based cements. Finally, Portland cements showed significantly higher mean solubility values compared to the other samples. The physicochemical properties of the tested materials in association with Aloe Vera were compatible with ANSI/ADA requirements, except for the white Portland cements, which failed to meet the radiopacity specification.

Experimental study of chloride diffusivity in unsaturated ordinary Portland cement mortar

NARCIS (Netherlands)

Zhang, Y.; Ye, G.; Santhanam, M.

2017-01-01

Experiments are carried out to investigate the chloride diffusivity in partially saturated ordinary Portland cement mortars with water-to-cement (w/c) ratios of 0.4, 0.5 and 0.6. Based on resistivity measurement and Nernst-Einstein equation, the chloride diffusivities of cement mortars at various

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

Science.gov (United States)

2011-08-31

... DEPARTMENT OF COMMERCE International Trade Administration [A-588-815] Gray Portland Cement and... portland cement and clinker from Japan. As a result of this third sunset review, the Department finds that... initiation of the third sunset review of the antidumping duty order on gray portland cement and clinker from...

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

Stabilization of chromium salt in ordinary portland cement

Indian Academy of Sciences (India)

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.

Presence of arsenic in different types of MTA and white and gray Portland cement.

Science.gov (United States)

Monteiro Bramante, Clóvis; Demarchi, Ana Claudia Cardoso Oliveira; de Moraes, Ivaldo Gomes; Bernadineli, Norberti; Garcia, Roberto Brandão; Spångberg, Lars S W; Duarte, Marco Antonio Hungaro

2008-12-01

The presence of arsenic in various types of mineral trioxide aggregate (MTA) and Portland cements were evaluated to verify if they comply with the ISO-recommended limit for water-based cements of 2 mg arsenic/kg material. An amount of 5 mL of hydrochloric acid was added to 2 g each of MTA and Portland cement to be analyzed. After 15 minutes, the material was filtered and the volume of supernatant was diluted with reagent-grade water up to 40 mL. Atomic absorption spectrophotometry readings were performed in triplicate. The following mean values were obtained: CPM (Egeo, Buenos Aires, Argentina) 11.06 mg/kg; CPM sealer (Egeo) 10.30 mg/kg; MTA-Obtura (Angelus, Londrina, PR, Brazil) 0.39 mg/kg; Experimental MTA: 10.30 mg/kg; White MTA-Angelus (Angelus) 1.03 mg/kg; Gray MTA-Angelus (Angelus) 5.91 mg/kg; ProRoot-MTA (Dentsply/Tulsa Dental Specialties, Tulsa, OK) 5.25 mg/kg; Gray Portland cement (Votorantim Cimentos, Cubatão, SP, Brazil): 34.27 mg/kg; and White Portland cement (Cimento Rio Branco, Rio de Janeiro, RJ, Brazil) 0.52 mg/kg. All tested materials presented arsenic in their composition. The form of arsenic was not analyzed nor the toxicity of the arsenic found. Only MTA-Obtura, White MTA-Angelus, and White Portland cement presented arsenic levels below the limit set in the ISO 9917-1 standard.

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

International Nuclear Information System (INIS)

Camarini, G.; Djanikian, J.G.

1994-01-01

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 95 0 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

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.

Sealing ability of mineral trioxide aggregate and Portland cement for furcal perforation repair: a protein leakage study.

Science.gov (United States)

Shahi, Shahriar; Rahimi, Saeed; Hasan, Maryam; Shiezadeh, Vahab; Abdolrahimi, Majid

2009-12-01

The purpose of this study was to compare the sealing ability of gray mineral trioxide aggregate (GMTA), white MTA (WMTA), and both white and gray Portland cement as furcation perforation repair materials. A total of 120 human mandibular first molars were used. After root canal obturation and preparation of furcal perforations the specimens were randomly divided into four groups of 25 teeth each. In groups A, B, C, and D furcation perforations were filled with WMTA, GMTA, white Portland cement, and type II Portland cement, respectively. Ten teeth were used as positive controls with no filling materials in the perforations and 10 teeth with complete coverage with two layers of nail varnish were used as negative controls. A protein leakage model utilizing 22% bovine serum albumin (BSA) was used for evaluation. Leakage was noted when color conversion of the protein reagent was observed. The controls behaved as expected. Leakage was found in the samples from group A (WMTA), group B (GMTA), and in the two other groups (white and gray Portland cement). There were no statistically significant differences between GMTA and WMTA or white and gray Portland cement, but significant differences were observed between the MTA groups and the Portland cement groups. It was concluded that Portland cements have better sealing ability than MTA, and can be recommended for repair of furcation perforation if the present results are supported by other in vivo and in vitro studies.

Utilization of steel slag for Portland cement clinker production.

Science.gov (United States)

Tsakiridis, P E; Papadimitriou, G D; Tsivilis, S; Koroneos, C

2008-04-01

The aim of the present research work is to investigate the possibility of adding steel slag, a by-product of the conversion of iron to steel process, in the raw meal for the production of Portland cement clinker. Two samples of raw meals were prepared, one with ordinary raw materials, as a reference sample ((PC)(Ref)), and another with 10.5% steel slag ((PC)(S/S)). Both raw meals were sintered at 1450 degrees C. The results of chemical and mineralogical analyses as well as the microscopic examination showed that the use of the steel slag did not affect the mineralogical characteristics of the so produced Portland cement clinker. Furthermore, both clinkers were tested by determining the grindability, setting times, compressive strengths and soundness. The hydration products were examined by XRD analysis at 2, 7, 28 and 90 days. The results of the physico-mechanical tests showed that the addition of the steel slag did not negatively affect the quality of the produced cement.

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

DEFF Research Database (Denmark)

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

2012-01-01

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

Alkali binding in hydrated Portland cement paste

NARCIS (Netherlands)

Chen, Wei; Brouwers, Jos

2010-01-01

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

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

Science.gov (United States)

2011-03-07

... Production Act of 1993--Portland Cement Association Notice is hereby given that, on February 02, 2011... seq. (``the Act''), Portland Cement Association (``PCA'') has filed written notifications..., Praxair, Danbury, CT; Metso Minerals, York, PA; Lehigh Cement Company LLC, Allentown, PA; Lehigh Northwest...

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

Science.gov (United States)

2011-06-13

... Production Act of 1993; Portland Cement Association Notice is hereby given that, on May 12, 2011, pursuant to.... (``the Act''), Portland Cement Association (``PCA'') has filed written notifications simultaneously with... plaintiffs to actual damages under specified circumstances. Specifically, Drake Cement, LLC, Scottsdale, AZ...

An Experimental Study of Portland Cement and Superfine Cement Slurry Grouting in Loose Sand and Sandy Soil

Directory of Open Access Journals (Sweden)

Weijing Yao

2018-04-01

Full Text Available Grouting technology is widely applied in the fields of geotechnical engineering in infrastructure. Loose sand and sandy soil are common poor soils in tunnel and foundation treatments. It is necessary to use superfine cement slurry grouting in the micro-cracks of soil. The different effectiveness of Portland cement slurry and superfine cement slurry in sandy soil by the laboratory grouting experiment method were presented in this paper. The grouting situations of superfine cement slurry injected into sand and sandy soil were explored. The investigated parameters were the dry density, wet density, moisture content, internal friction angle, and cohesion force. The results show that the consolidation effect of superfine cement is better than that of Portland cement due to the small size of superfine cement particles. The superfine cement can diffuse into the sand by infiltration, extrusion, and splitting. When the water–cement ratio of superfine cement slurry is less than 2:1 grouting into loose sand, the dry and wet density decrease with the increase in the water–cement ratio, while the moisture content and cohesive force gradually increase. When the water–cement ratio of superfine cement slurry is 1:1 grouting into loose sand and sandy soil, the dry density, wet density, and cohesive force of loose sand are larger than those of sandy soil. The results of the experiment may be relevant for engineering applications.

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

Science.gov (United States)

2010-01-27

... Production Act of 1993--Portland Cement Association Notice is hereby given that, on December 14, 2009... seq. (``the Act''), Portland Cement Association (``PCA'') has filed written notifications... Cement, Hannibal, MO has been added as a party to this venture. Also, the following parties have...

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

Directory of Open Access Journals (Sweden)

Adriano Papo

2010-01-01

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

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

Science.gov (United States)

2012-02-03

... Production Act of 1993--Portland Cement Association Notice is hereby given that, on January 6, 2012, pursuant... seq. (``the Act''), Portland Cement Association (``PCA'') has filed written notifications..., Newark, DE, has been added as a party to this venture. Also, Texas-Lehigh Cement Company, Buda, TX...

Effects of the super plasticizers and the water/cement ratio on the mini-slump of Portland cement pastes

International Nuclear Information System (INIS)

Meirelles, J.R.; Morelli, A.C.; Baldo, J.B.

1998-01-01

The rheology of Portland cement concrete is dominated by the cement paste rheology. In general the rheological behavior of cement pastes is evaluated by means of the mini-slump test. In the present paper it was investigated the effect of the water/cement ratio was as of two types of superplasticizers (melamine and naftalen based) on the mini-slump of pastes of common cement pastes. (author)

XRF analysis of portland cement for major and trace elements

International Nuclear Information System (INIS)

Abdunnabi, A. R.

2012-12-01

Libyan portland cement produced in several factories around the country, in Lip tis, Zoltan, Souq-Elkamis, Dernah and El-Fatach, were analyzed for quantitative major and trace elements and mineral content, which were compered with those imported from Spain, Romania, Cyprus, and Egypt. X-ray fluorescence spectro X lab 2000 spectrometer equipped with Rh-and X-ray tube was used for the analysis of various samples. The detector Si(Li) with a resolution of 148 eV at Mn K-a=5.9 keV facilitates the determination of a wide range of elements from sodium to uranium, with a detection limit at sub levels. Cement samples in the powder form were analyzed using the pellet-technique. The pellets were prepared by mixing 4g of the cement powder with 0.9 g of binder (HWC) and pressed at high pressure. A ful analysis including, background counting, matrix correction and all relevant corrections were achieved automatically by XLAB 2000 software package. For major and trace elements X RF results were higher for most of the elements than those analyzed with atomic absorption spectrometry. The mineral content showed that Libyan cement is comparable to the imported ones, also the Libyan cement meets the requirements of the international specifications of the portland cement. (Author)

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

Directory of Open Access Journals (Sweden)

Guryanov Alexander

2016-01-01

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

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.

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

Science.gov (United States)

Gonçalves, Jorge Luis; Viapiana, Raqueli; Miranda, Carlos Eduardo Saraiva; Borges, Alvaro Henrique; Cruz Filho, Antônio Miranda da

2010-01-01

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.

Use of red mud as addition for portland cement mortars

International Nuclear Information System (INIS)

Ribeiro, D.V.; Morelli, M.R.

2011-01-01

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)

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

Science.gov (United States)

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

2015-12-01

The objective of this research was to evaluate the response of Portland cement associated with different radio pacifying agents on pulp treatment of human primary teeth by clinical and radiographic exams and microscopic analysis. Thirty mandibular primary molars were randomly divided into the following groups: Group I - Portland cement; Group II - Portland cement with iodoform (Portland cement + CHI3 ); Group III - Portland cement with zirconium oxide (Portland cement + ZrO2 ); and treated by pulpotomy technique (removal of a portion of the pulp aiming to maintain the vitally of the remaining radicular pulp tissue using a therapeutic dressing). Clinical and radiographic evaluations were recorded at 6, 12 and 24 months follow-up. The teeth at the regular exfoliation period were extracted and processed for histological analysis. Data were tested using statistical analysis with a significance level of 5%. The microscopic findings were descriptively analysed. All treated teeth were clinically and radiographically successful at follow-up appointments. The microscopic analysis revealed positive response to pulp repair with hard tissue barrier formation and pulp calcification in the remaining roots of all available teeth. The findings of this study suggest that primary teeth pulp tissue exhibited satisfactory biological response to Portland cement associated with radio pacifying agents. However, further studies with long-term follow-up are needed to determine the safe clinical indication of this alternative material for pulp therapy of primary teeth. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Incorporation of cement bypass flue dust in fly ash and blast furnace slag-based geopolymer

Directory of Open Access Journals (Sweden)

Mohamed E. Sultan

2018-06-01

Full Text Available This work utilizes cement kiln dust in fly ash and blast furnace slag-based geopolymer. Geopolymer cement was produced using different compositions of ground, granulated blast furnace slag with fly ash and cement bypass flue dust. Crystalline sodium metasilicate pentahydrate was used as an activator at 10, 15 and 20% (by weight of the geopolymer source materials. The geopolymer is formed in the solid state like ordinary Portland cement. The mechanical and chemical properties of the geopolymeric materials were examined. Measuring of mechanical properties by compressive strength of the hardened geopolymer pastes at different curing ages; microstructure was evaluated by X-ray diffraction (XRD and scanning electron microscope (SEM; thermal properties were estimated by thermogravimetry analysis (TGA and derivative thermogravimetric analysis (DTG. The results indicate that the compressive strength of the geopolymer pastes is increased with higher Na2SiO3.5H2O content. The geopolymeric properties were enhanced by higher pH, which helps in the dissolution of geopolymer source materials during geopolymerization. SEM showed that mixes containing 15 and 20% sodium metasilicate had more compact and dense structures. On the other hand, GGBFS mix (G-20 exhibits more hydration and geopolymeric products during TGA/DTG compared with other mixes which contain FA with/without GGBFS. Keywords: Cement bypass flue dust, Geopolymer, Ground granulated blast furnace, Fly ash

Partial replacement of Portland cement by red ceramic waste in mortars: study of pozzolanic activity

International Nuclear Information System (INIS)

Silva, A.R. da; Cabral, K.C.; Pinto, E.N. de M.G.l.

2016-01-01

The objective of this study is to analyze the pozzolanic activity of red ceramic residue on the partial replacement of Portland cement in mortars. The mortars were prepared by substituting 25% of the Portland cement for ground of ceramic residue with water cement’s factor of 0.48. The concrete used to construct the reference mortars and those with addiction was CPII-Z-32 (compound of Portland pozzolana cement). The chemical analysis and physical ceramic waste showed that this meets the requirements of NBR12653 (2014) for use as pozzolanic material. The pozzolanic activity index (IAP) obtained for the ceramic waste to twenty-eight days cure rate was 80.28%. (author)

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.

Root perforations treatment using mineral trioxide aggregate and Portland cements.

Science.gov (United States)

Silva Neto, José Dias da; Brito, Rafael Horácio de; Schnaider, Taylor Brandão; Gragnani, Alfredo; Engelman, Mírian; Ferreira, Lydia Masako

2010-12-01

Clinical, radiological and histological evaluation of root perforations treated with mineral trioxide aggregate (MTA) or Portland cements, and calcium sulfate barrier. One molar and 11 premolar teeth of a male mongrel dog received endodontic treatment and furcations were perforated with a high-speed round bur and treated with a calcium sulfate barrier. MTA, Portland cement type II (PCII) and type V (PCV), and white Portland cement (WPC) were used as obturation materials. The teeth were restored with composite resin and periapical radiographs were taken. The animal was euthanized 120 days post-surgery for treatment evaluation. Right lower first premolar (MTA), right lower third premolar (PCV), left lower second premolar (MTA), and right lower second premolar (WPC): clinically normal, slightly radio-transparent area on the furcation, little inflammatory infiltrate, and new-bone formation. Left lower third premolar (PCII), right upper first premolar (WPC), right upper third premolar (PCII), and left upper first molar (PCV): clinically normal, radiopaque area on the furcation, and new-bone formation. Right upper second premolar (MTA), left upper second premolar (WPC), left upper third premolar (PCII): presence of furcation lesion, large radiolucent area, and intense inflammatory infiltrate. All obturation materials used in this study induced new-bone formation.

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

Science.gov (United States)

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

2012-02-21

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

Study of irradiation damage by fast neutrons in samples of Portland cement

International Nuclear Information System (INIS)

Lucki, G.; Rosa Junior, A.A.

1984-01-01

The effect of neutron irradiation in samples of Portland cement was evaluated, using the resonance frequency method and pulse velocity of ultra-sound techniques. The samples were divided in three groups: 1) monitoring samples; 2) samples submitted to gamma heating; 3) Irradiated samples. In the sample preparation, it was used the Portland Santa Rita CP 320 cement, and water-cement rate of 0.40 l/Kg. The irradiation was done in the research reactor IEA-R1, at IPEN - CNEN/SP, with an integrated flux of 7.2 x 10 18 n/cm 2 (E approx. 1 MeV). Some damage were detected, due to the neutron flux, and by the thermal effect of gamma heating. (E.G.) [pt

An Experimental Study of Portland Cement and Superfine Cement Slurry Grouting in Loose Sand and Sandy Soil

OpenAIRE

Weijing Yao; Jianyong Pang; Yushan Liu

2018-01-01

Grouting technology is widely applied in the fields of geotechnical engineering in infrastructure. Loose sand and sandy soil are common poor soils in tunnel and foundation treatments. It is necessary to use superfine cement slurry grouting in the micro-cracks of soil. The different effectiveness of Portland cement slurry and superfine cement slurry in sandy soil by the laboratory grouting experiment method were presented in this paper. The grouting situations of superfine cement slurry inject...

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....

Personal exposure to inhalable cement dust among construction workers

International Nuclear Information System (INIS)

Peters, Susan; Kromhout, Hans; Thomassen, Yngvar; Fechter-Rink, Edeltraud

2009-01-01

A case study was carried out in 2006-2007 to assess the actual cement dust exposure among construction workers involved in a full-scale construction project and as a comparison among workers involved in various stages of cement and concrete production. Full-shift personal exposure measurements were performed for several job types. Inhalable dust and cement dust (based on analysis of elemental calcium) concentrations were determined. Inhalable dust exposures at the construction site ranged from 0.05 to 34 mg/m3, with a mean concentration of 1.0 mg/m3. For inhalable cement dust mean exposure was 0.3 mg/m3 (range 0.02-17 mg/m3). Reinforcement and pouring workers had the lowest average concentrations. Inhalable dust levels in the ready-mix and pre-cast concrete plants were, on average, below 0.5 mg/m3 for inhalable dust and below 0.2 mg/m3 for inhalable cement dust. Highest dust concentrations were measured in cement production, particularly during cleaning tasks (inhalable dust GM=55 mg/m3; inhalable cement dust GM=33 mg/m3) at which point the workers wore personal protective equipment. Elemental measurements showed highest but very variable cement percentages in the cement plant and very low percentages of cement during reinforcement work and pouring.

Comparative evaluation of antimicrobial activity of three cements: new endodontic cement (NEC), mineral trioxide aggregate (MTA) and Portland.

Science.gov (United States)

Hasan Zarrabi, Mohammad; Javidi, Maryam; Naderinasab, Mahboube; Gharechahi, Maryam

2009-09-01

Using the agar diffusion method, we conducted an in vitro study to evaluate the antimicrobial activity of mineral trioxide aggregate (MTA), new endodontic cement (NEC) and Portland cement at different concentrations against five different microorganisms. A base layer was made using Muller-Hinton agar for Escherichia coli (ATCC 10538) and Candida (ATCC 10231). For Actinomyces viscosus (ATCC 15987), Enterococcus faecalis (ATCC 10541) and Streptococcus mutans (ATCC 25175) blood agar medium was used. Wells were formed by removing the agar, and the materials were placed in the well immediately after manipulation. The plates were kept at room temperature for 2 h for prediffusion, and then incubated at 37 degrees C for 72 h. The inhibition zones were then measured. The data were analyzed using ANOVA and the Tukey test to compare the differences among the three cements at different concentrations. The positive controls showed bacterial growth, while the negative controls showed no bacterial growth. All materials showed antimicrobial activity against the tested strains except for Enterococcus faecalis. NEC created larger inhibition zones than MTA and Portland cement. This difference was significant for Portland cement (P 0.05). Among the examined microorganisms, the largest inhibition zone was observed for Actinomyces group (P < 0.05). The antimicrobial activity of the materials increased with time and concentration (P < 0.05). It was concluded that NEC is a potent inhibitor of microorganism growth.

Study of the bismuth oxide concentration required to provide Portland cement with adequate radiopacity for endodontic use.

Science.gov (United States)

Bueno, Carlos Eduardo da Silveira; Zeferino, Eduardo Gregatto; Manhães, Luiz Roberto Coutinho; Rocha, Daniel Guimarães Pedro; Cunha, Rodrigo Sanches; De Martin, Alexandre Sigrist

2009-01-01

The purpose of this study was to determine the ideal concentration of bismuth oxide in white Portland cement to provide it with sufficient radiopacity for use as an endodontic material (ADA specification #57). 2-mm thick standardized test specimens of white MTA and of white Portland cement, as controls, and of white Portland cement with the experimental addition of 5%, 10%, 15%, 20%, 25% or 30% of bismuth oxide were radiographed and compared with various thicknesses of pure aluminum, using optic density to determine the observed grayscale levels of radiopacity in a scale ranging from 0 to 255. The data was submitted to ANOVA (pcement with 0%, 5%, 10%, 15%, 20%, 25% and 30% of bismuth oxide presented mean readings of 63.3, 95.7, 110.7, 142.7, 151.3, 161.0 and 180.0 respectively. MTA presented a mean reading of 157.3. The readings of MTA and white Portland cement with 15% bismuth oxide did not differ significantly from the reading observed for a thickness of 4 mm of aluminum (145.3), which is considered ideal for a test specimen by ADA specification #57 (2 mm above the thickness of the test specimen). White MTA and white Portland cement with 15% bismuth oxide presented the radiopacity required for an endodontic cement.

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

International Nuclear Information System (INIS)

Shatta, H.A.; Saleh, H.M.

2006-01-01

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

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

Science.gov (United States)

Karanth, P; Manjunath, M K; Kuriakose, E S

2013-01-01

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. 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. 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. 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.

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.

Description of the structural evolution of a hydrating portland cement paste by SANS

International Nuclear Information System (INIS)

Haeussler, F.; Eichhorn, F.; Baumbach, H.

1994-01-01

On the spectrometer MURN at the pulsed reactor IBR-2 dry Portland cement, silica fume, and a hydrating Portland cement paste were studied by small-angle neutron scattering (SANS). By using the TOF-method a momentum transfer from 0.07 nm -1 to 7 nm -1 is detectable. Every component (dry cement powder, clinker minerals, hydrating cement pastes) shows a different scattering behaviour. In the measured Q-region the hardening cement paste does not show a Porod-like behaviour of SANS-curves. In contrast the Porod's potential law holds for dry powder samples of clinker minerals and silica fume. In experiments carried out to observe the hydration progress within the first 321 days the characteristics of the scattering curves (potential behaviour, the radius of gyration, and the macroscopic scattering cross section at Q = 0 nm -1 were measured. Some evolution of the inner structure of the hardened cement paste was noted. (orig.)

Hydration rate and strength development of low-heat type portland cement mortar mixed with pozzolanic materials

International Nuclear Information System (INIS)

Matsui, Jun

1998-01-01

Recently, low-heat type Portland cement was specified in Japan Industrial Standards (JIS). Its hydration proceeds slowly. The results of the research so far obtained indicate that slow hydration of cement and mixing of pozzolanic materials with cement make micro-structure of harded cement paste dense and durable. In this study, a blended cement using low-heat type Portland cement and some of pozzolanic materials has been newly developed and its strength property and hydration ratio were checked. The followings are conclusion. (1) Hydration rate of cement paste varies with the replacement ratio of pozzolanic materials. (2) A good liner relationship between strength and total hydration rate of cement paste was observed. (3) A proper replacement ratio of both base-cement and pozzolanic material for manufacturing a blended cement is 50%. (author)

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

International Nuclear Information System (INIS)

Benakli, A.; Chomat, L.; Le Bescop, P.; Wall, J.

2015-01-01

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 (Mg 2+ , Na + ) and anions (SO 4 2- ) 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

Effects of cement particle size distribution on performance properties of Portland cement-based materials

Energy Technology Data Exchange (ETDEWEB)

Bentz, D.P.; Garboczi, E.J.; Haecker, C.J.; Jensen, O.M.

1999-10-01

The original size, spatial distribution, and composition of Portland cement particles have a large influence on hydration kinetics, microstructure development, and ultimate properties of cement-based materials. In this paper, the effects of cement particle size distribution on a variety of performance properties are explored via computer simulation and a few experimental studies. Properties examined include setting time, heat release, capillary porosity percolation, diffusivity, chemical shrinkage, autogenous shrinkage, internal relative humidity evolution, and interfacial transition zone microstructure. The effects of flocculation and dispersion of the cement particles in the starting microstructures on resultant properties are also briefly evaluated. The computer simulations are conducted using two cement particle size distributions that bound those commonly in use today and three different water-to-cement ratios: 0.5, 0.3, and 0.246. For lower water-to-cement ratio systems, the use of coarser cements may offer equivalent or superior performance, as well as reducing production costs for the manufacturer.

Personal exposure to inhalable cement dust among construction workers.

Science.gov (United States)

Peters, Susan; Thomassen, Yngvar; Fechter-Rink, Edeltraud; Kromhout, Hans

2009-01-01

Objective- A case study was carried out to assess cement dust exposure and its determinants among construction workers and for comparison among workers in cement and concrete production.Methods- Full-shift personal exposure measurements were performed and samples were analysed for inhalable dust and its cement content. Exposure variability was modelled with linear mixed models.Results- Inhalable dust concentrations at the construction site ranged from 0.05 to 34 mg/m(3), with a mean of 1.0 mg/m(3). Average concentration for inhalable cement dust was 0.3 mg/m(3) (GM; range 0.02-17 mg/m(3)). Levels in the ready-mix and pre-cast concrete plants were on average 0.5 mg/m(3) (GM) for inhalable dust and 0.2 mg/m(3) (GM) for inhalable cement dust. Highest concentrations were measured in cement production, particularly during cleaning tasks (inhalable dust GM = 55 mg/m(3); inhalable cement dust GM = 33 mg/m(3)) at which point the workers wore personal protective equipment. Elemental measurements showed highest but very variable cement percentages in the cement plant and very low percentages during reinforcement work and pouring. Most likely other sources were contributing to dust concentrations, particularly at the construction site. Within job groups, temporal variability in exposure concentrations generally outweighed differences in average concentrations between workers. 'Using a broom', 'outdoor wind speed' and 'presence of rain' were overall the most influential factors affecting inhalable (cement) dust exposure.Conclusion- Job type appeared to be the main predictor of exposure to inhalable (cement) dust at the construction site. Inhalable dust concentrations in cement production plants, especially during cleaning tasks, are usually considerably higher than at the construction site.

Nanotechnology-Based Performance Improvements For Portland Cement Concrete - Phase I

Science.gov (United States)

2012-08-16

A fundamental understanding of the nano-structure of Portland cement concrete (PCC) is the key to realizing significant breakthroughs regarding high performance and susta : (MBTC 2095/3004) using molecular dynamics (MD) provided new understanding of ...

The Influence of Diatomite on the Strength and Microstructure of Portland Cement

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Liu Jun

2016-01-01

Full Text Available To study the influence of the types and mixing amount of diatomite on the Portland cement, we prepared the cement specimen doped with the calcined first-grade, first-grade and second-grade diatomite ,tested the 3d, 7d, 14d compressive strength, and studied and discussed phase, structure and morphology of diatomite in the binary system by the method of XRD, SEM . Experimental results show that with the addition of diatomite, the strength of cement paste increase; the optimal contents of calcined first-grade ,first-grade and second-grade diatomite in Portland cement are 5%,Compared to the blank group, the strength of specimen can be increased by 54.6%, 15.4% and 10.2%, respectively; At the same time ,the 7d microscopic hydration of different diatomite particles were analyzed through the experiment , and the shell of calcined diatomite particles were better hydrated than that of first-grade and second-grade diatomite particles. The results indicate that the diatomite can improve the strength of cement paste, the hydration of different diatomite particles can influence the growth of cement paste strength.

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

International Nuclear Information System (INIS)

Elbeyli, Iffet Yakar; Derun, Emek Moeroeydor; Guelen, Jale; Piskin, Sabriye

2003-01-01

Borogypsum, which consists mainly of gypsum crystals, B 2 O 3 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

Low porosity portland cement pastes based on furan polymers

International Nuclear Information System (INIS)

Darweesh, H.H.M.

2005-01-01

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

Toxicity and Histopathological Effects of Portland Cement Powder in ...

African Journals Online (AJOL)

Hepatic lesions in the liver tissues of fish exposed to Portland cement powder in solution were characterized by degeneration of hepatocyte, vascuolization of cell cytoplasm, fatty degeneration and hypertrophy of hepatocytes. Histological comparison of tissues indicated that most damage occurred in the gill rather than in ...

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

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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.

Portland cement for SO.sub.2 control in coal-fired power plants

Science.gov (United States)

Steinberg, Meyer

1985-01-01

There is described a method of removing oxides of sulfur from the emissions of fossil fuel combustion by injecting portland cement into the boiler with the fuel, the combustion air, or downstream with the combustion gases. There is also described the cement products that result from this method.

Portland cement for SO/sub 2/ control in coal-fired power plants

Science.gov (United States)

Steinberg, M.

1984-10-17

A method is described for removing oxides of sulfur from the emissions of fossil fuel combustion by injecting portland cement into the boiler with the fuel, the combustion air, or downstream with the combustion gases. The cement products that result from this method is also described. 1 tab.

Setting time and flowability of accelerated Portland cement mixed with polycarboxylate superplasticizer.

Science.gov (United States)

Wongkornchaowalit, Norachai; Lertchirakarn, Veera

2011-03-01

Important limitations of mineral trioxide aggregate for use in clinical procedures are extended setting time and difficult handling characteristics. The removal of gypsum at the end stage of the Portland cement manufacturing process and polycarboxylate superplasticizer admixture may solve these limitations. Different concentrations of polycarboxylate superplasticizer (0%, 1.2%, 1.8%, and 2.4% by volume) and liquid-to-powder ratios (0.27, 0.30, and 0.33 by weight) were mixed with white Portland cement without gypsum (AWPC-experimental material). Type 1 ordinary white Portland cement mixed with distilled water at the same ratios as the experimental material was used as controls. All samples were tested for setting time and flowability according to the International Organization for Standardization 6876:2001 guideline. The data were analyzed by two-way analysis of variance. Then, one-way analysis of variance and multiple comparison tests were used to analyze the significance among groups. The data are presented in mean ± standard deviation values. In all experimental groups, the setting times were in the range of 4.2 ± 0.4 to 11.3 ± 0.2 minutes, which were significantly (p setting time and increased flowability of cement, which would be beneficial for clinical use. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Radiopacity and histological assessment of Portland cement plus bismuth oxide.

Science.gov (United States)

Coutinho-Filho, Tauby; De-Deus, Gustavo; Klein, Leila; Manera, Gisele; Peixoto, Carla; Gurgel-Filho, Eduardo Diogo

2008-12-01

The present study evaluated the subcutaneous connective tissue reactions and the radiopacity of MTA, Portland cement (PC), and Portland cement plus bismuth oxide (BO). Forty rats were divided into 5 groups (n = 8 per group): A1: Control (empty capsule); A2: Pro-Root MTA; A3: PC; A4: PC + BO 1:1; and A5: PC + BO 2:1. Polyethylene tubes were filled with the test materials and standardized radiographic images were taken. Histological evaluation was done after 7 and 60 days. Student t test and Fisher's test were used in the statistical analysis (P A4 > A5 > A3. No differences were found for the tissue response in the 2 experimental periods. A positive correlation between BO concentration and radiopacity of PC was determined. The histological evaluation suggests that all studied materials were biocompatible at 7 and 60 days.

The AFm phase in Portland cement

International Nuclear Information System (INIS)

Matschei, T.; Lothenbach, B.; Glasser, F.P.

2007-01-01

The AFm phase of Portland cements refers to a family of hydrated calcium aluminates based on the hydrocalumite-like structure of 4CaO.Al 2 O 3 .13-19 H 2 O. However OH - may be replaced by SO 4 2- and CO 3 2- . Except for limited replacement (50 mol%, maximum) of sulfate by hydroxide, these compositions do not form solid solutions and, from the mineralogical standpoint, behave as separate phases. Therefore many hydrated cements will contain mixtures of AFm phases. AFm phases have been made from precursors and experimentally-determined phase relationships are depicted at 25 deg. C. Solubility data are reported and thermodynamic data are derived. The 25 deg. C stability of AFm phases is much affected by the nature of the anion: carbonate stabilises AFm and displaces OH and SO 4 at species activities commonly encountered in cement systems. However in the presence of portlandite, and as carbonate displaces sulfate in AFm, the reaction results in changes in the amount of both portlandite and ettringite: specimen calculations are presented to quantify these changes. The scheme of phase balances enables calculation of the mineralogical balances of a hydrated cement paste with greater accuracy than hitherto practicable

A thermodynamic approach to the hydration of sulphate-resisting Portland cement

International Nuclear Information System (INIS)

Lothenbach, Barbara; Wieland, Erich

2006-01-01

A thermodynamic approach is used to model changes in the hydrate assemblage and the composition of the pore solution during the hydration of calcite-free and calcite-containing sulphate-resisting Portland cement CEM I 52.5 N HTS. Modelling is based on thermodynamic data for the hydration products and calculated hydration rates for the individual clinker phases, which are used as time-dependent input parameters. Model predictions compare well with the composition of the hydrate assemblage as observed by TGA and semi-quantitative XRD and with the experimentally determined compositions of the pore solutions. The calculations show that in the presence of small amounts of calcite typically associated with Portland cement, C-S-H, portlandite, ettringite and calcium monocarbonate are the main hydration products. In the absence of calcite in the cement, however, siliceous hydrogarnet instead of calcium monocarbonate is observed to precipitate. The use of a higher water-to-cement ratio for the preparation of a calcite-containing cement paste has a minor effect on the composition of the hydrate assemblage, while it significantly changes the composition of the pore solution. In particular, lower pH value and higher Ca concentrations appear that could potentially influence the solubility and uptake of heavy metals and anions by cementitious materials

D90: The Strongest Contributor to Setting Time in Mineral Trioxide Aggregate and Portland Cement.

Science.gov (United States)

Ha, William N; Bentz, Dale P; Kahler, Bill; Walsh, Laurence J

2015-07-01

The setting times of commercial mineral trioxide aggregate (MTA) and Portland cements vary. It was hypothesized that much of this variation was caused by differences in particle size distribution. Two gram samples from 11 MTA-type cements were analyzed by laser diffraction to determine their particle size distributions characterized by their percentile equivalent diameters (the 10th percentile, the median, and the 90th percentile [d90], respectively). Setting time data were received from manufacturers who performed indentation setting time tests as specified by the standards relevant to dentistry, ISO 6786 (9 respondents) or ISO 9917.1 (1 respondent), or not divulged to the authors (1 respondent). In a parallel experiment, 6 samples of different size graded Portland cements were produced using the same cement clinker. The measurement of setting time for Portland cement pastes was performed using American Society for Testing and Materials C 191. Cumulative heat release was measured using isothermal calorimetry to assess the reactions occurring during the setting of these pastes. In all experiments, linear correlations were assessed between setting times, heat release, and the 3 particle size parameters. Particle size varied considerably among MTA cements. For MTA cements, d90 was the particle size characteristic showing the highest positive linear correlation with setting time (r = 0.538). For Portland cement, d90 gave an even higher linear correlation for the initial setting time (r = 0.804) and the final setting time (r = 0.873) and exhibited a strong negative linear correlation for cumulative heat release (r = 0.901). Smaller particle sizes result in faster setting times, with d90 (the largest particles) being most closely correlated with the setting times of the samples. Copyright © 2015 American Association of Endodontists. All rights reserved.

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

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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.

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

International Nuclear Information System (INIS)

Gougar, M.L.D.; Scheetz, B.E.; Roy, D.M.

1996-01-01

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

Early hydration of portland cement with crystalline mineral additions

International Nuclear Information System (INIS)

Rahhal, V.; Talero, R.

2005-01-01

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

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

International Nuclear Information System (INIS)

Gallego, Daniel; Higuita, Natalia; Garcia, Felipe; Ferrell, Nicholas; Hansford, Derek J.

2008-01-01

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 2 atmosphere, allowing the formation of CaCO 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 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) 2 on C-, and CaCO 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

Predicting the durability of Portland cement systems in aggressive environments--Laboratory validation

International Nuclear Information System (INIS)

Maltais, Y.; Samson, E.; Marchand, J.

2004-01-01

Portland cement systems are often exposed to severe environments, and their long-term performance is of concern. The main results of a comprehensive investigation of deterioration processes that may affect the behavior of Portland cement systems exposed to chemically aggressive environments is presented. As part of this investigation, well-cured cement paste discs were fully characterized and exposed to deionized water and sodium sulfate solutions. Degradation experiments were conducted under saturated and unsaturated conditions. At the end of the exposure period, microstructural alterations were investigated by microprobe analyses, scanning electron microscope observations and energy-dispersive X-ray analyses. Test results provide information on the basic aspects of various degradation phenomena, such as decalcification and external sulfate attack. Experimental results were also compared with results obtained by a numerical model. The analysis reveals that the intricate microstructural features of the degraded samples could be accurately reproduced by the model

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

International Nuclear Information System (INIS)

Wieland, E.; Tits, J.; Spieler, P.; Dobler, J.-P.

1998-01-01

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 . 85 Sr, 63 Ni and 125 I 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 (R d ) on the concentration of ISA and on the concentration of cement particles (S:L ratio). In the case of 63 Ni and 125 I a strong decrease in the distribution ratio (R d ) 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 63 Ni 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)

Effect of calcium/silicon ratio on retention of uranium (VI) in portland cement materials

International Nuclear Information System (INIS)

Tan Hongbin; Li Yuxiang

2005-01-01

Calcium silicate hydrate (CSH) materials of varied calcium to silicon (Ca/Si) ratios were prepared by hydrothermal synthesis at 80 degree C, with calcium oxide and micro-silicon employed. These products were determined to be of gel phase by XRD. Leaching tests with 1% hydrochloric acid indicated that more Uranium (VI) was detained by CSH with lower Ca/Si ratios. Alkali-activated slag cement (with a lower Ca/Si ratio) was found to have a stronger retention capacity than Portland cement (with a higher Ca/Si ratio), at 25 degree C in 102-days leaching tests with simulated solidified forms containing Uranium (VI). The accumulative leaching fraction of Uranium (VI) for Alkali-activated slag cement solidified forms is 17.6% lower than that for Portland cement. The corresponding difference of diffusion coefficients is 40.6%. This could be correlated with the difference of Ca/Si ratios between cements of two kinds. (authors)

Ecological indices of manufacture of Portland cement clinker and production of the dolomite clinker

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Vinnichenko Varvara

2017-01-01

Full Text Available It is shown that the production of dolomite clinker in comparison with that of Portland cement is environmentally appropriate. When calcining dolomite for cementitious binder, the pollution of the atmosphere by carbon dioxide is reduced due to its isolation during decarbonization reactions of calcium carbonates. Reducing fuel consumption for clinker burning provides less carbon dioxide emissions from combustion products. Reducing the firing temperature creates obstacles to the formation of nitrogen oxides. The production of binders from dolomite in comparison with the production of Portland cement helps to protect the environment from contamination

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

Science.gov (United States)

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

2014-03-01

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

Analysis of heavy metal contents in gray and white MTA and 2 kinds of Portland cement: a preliminary study.

Science.gov (United States)

Chang, Seok Woo; Shon, Won Jun; Lee, WooCheol; Kum, Kee Yeon; Baek, Seung Ho; Bae, Kwang Shik

2010-04-01

The levels of 10 heavy metals (arsenic, bismuth, cadmium, chromium, copper, iron, lead, manganese, nickel, and zinc) in gray Portland cement (GPC), white Portland cement (WPC), gray MTA (GMTA), and white MTA (WMTA) were analyzed by inductively coupled plasma-atomic emission spectrometry (ICP-AES). One gram of each material was digested with 80 degrees C "aqua-regia" (7 mL of 60% HNO3 and 21 mL of 35% HCl), filtered, and analyzed by ICP-AES. The analysis was performed 6 times and the data were analyzed statistically. Arsenic and lead concentrations were the highest in GPC (P cements (P Portland cement versus MTA, the differences in purity may be considered. Copyright 2010 Mosby, Inc. All rights reserved.

Puzzolanic cements of greater resistance at the attack of selenitic waters than the high sulfate resistance portland cements, and viceverse

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Talero, Rafael

1987-09-01

Full Text Available This work confirms the certainty of the predictions of useful service given by Kaluosek and al. for the sulphate resistant portland cements (type V, USA, subject to severe selenitic attack. Two sulphate resistant portland cements, were tested by means of the Le Chatelier Anstett method. The tarts were destroyed at ages of three years, having detected in them the presence of thaumasite by XRD. Even so, the impossibility and possibility thaumasite formation was confirmed in pozzolanic cements tarts, which either had or did not have adequate amount of pozzolana (diatomite for such purpose.

Este trabajo confirman las predicciones de vida útil dadas por Kalousek y colaboradores, para los cementos portland de elevada resistencia al ataque de los iones sulfato (tipo V, USA, sometidos a un severo ataque selenitoso. Se ensayaron dos cementos portland de elevada resistencia al ataque del yeso, mediante el ensayo de Le Chatelier-Anstett. Sus tortas correspondientes se destruyeron a la edad de tres años, habiéndose detectado en las mismas la presencia de thaumasita por DRX. Asimismo se confirmó la imposibilidad y posibilidad de formación de thaumasita en tortas de cementos puzolánicos, los cuales tenían, o no, respectivamente, una adecuada cantidad de puzolana (diatomita para tales fines.

Effect of addition of Sikament-R superplasticizer on the hydration characteristics of portland cement pastes

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Safaa.M. El Gamal

2012-08-01

Full Text Available The effect of addition of Sikament-R superplasticizer (modified lignosulphonate base on the hydration characteristics of hardened Portland cement pastes were studied at different curing conditions. Four mixtures were prepared using 0, 0.2, 0.4 and 0.6 wt% addition of Sikament-R superplasticizer (SR of cement. These pastes were hydrated under two different conditions; (i normal curing at room temperature; 25 °C up to 90 days periods and (ii hydrothermal curing at a pressure of 8 atm. of saturated steam up to 24 h. The compressive strength, combined water content, free lime content, gel/space ratio and microstructure of hardened cement pastes were studied. The results revealed that addition of SR superplasticizer promote the dispersion of cement particles and interacts with Ca(OH2. The addition of SR superplasticizer exhibits Portland cement better workability during the preparation of pastes. In addition, amore compact structure were obtained leading to higher values of compressive strength for all the hardened hydrated pastes under both normal and hydrothermal curing. The results indicated that the addition of SR superplasticizer to Portland cement does not alter the types of hydration products formed during normal or hydrothermal conditions; only it caused a decrease in the degree of the porosity of the formed pastes.

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

OpenAIRE

Yusnita, Heni

2011-01-01

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

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.

Radioactive waste-Portland cement systems: I, radionuclide distribution

International Nuclear Information System (INIS)

Jantzen, C.M.; Glasser, F.P.; Lachowski, E.E.

1984-01-01

Crystal chemical stabilization of radioactive wastes can be achieved during clinkering of, or with, ordinary portland cement. Waste loadings of 20 to 30 wt% are achieved by dilute solid solution of waste ions into cementitious host lattices. Higher waste loadings result in compatible noncementitious radiophases. The cementitious phases hydrate without loss of compressive strength. Crystallochemical relationships predict that the radionuclide partitioning in the anhydrous clinkered phases will be maintained in the hydration products. These cementitious hydroxylated radiophases would be in internal equilibrium under anticipated repository conditions. The radionuclide distributions observed are described in the context of established phase equilibria for commercial waste cement systems, but are applicable to transuranic, medium- and low-level wastes

Thermodynamic modelling of the effect of temperature on the hydration and porosity of Portland cement

International Nuclear Information System (INIS)

Lothenbach, Barbara; Matschei, Thomas; Moeschner, Goeril; Glasser, Fred P.

2008-01-01

The composition of the phase assemblage and the pore solution of Portland cements hydrated between 0 and 60 deg. C were modelled as a function of time and temperature. The results of thermodynamic modelling showed a good agreement with the experimental data gained at 5, 20, and 50 deg. C. At 5 and at 20 deg. C, a similar phase assemblage was calculated to be present, while at approximately 50 deg. C, thermodynamic calculations predicted the conversion of ettringite and monocarbonate to monosulphate. Modelling showed that in Portland cements which have an Al 2 O 3 /SO 3 ratio of > 1.3 (bulk weight), above 50 deg. C monosulphate and monocarbonate are present. In Portland cements which contain less Al (Al 2 O 3 /SO 3 < 1.3), above 50 deg. C monosulphate and small amounts of ettringite are expected to persist. A good correlation between calculated porosity and measured compressive strength was observed

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

Comparative study of physico-chemical properties of MTA-based and Portland cements.

Science.gov (United States)

Borges, Alvaro H; Pedro, Fábio L M; Miranda, Carlos E S; Semenoff-Segundo, Alex; Pécora, Jesus D; Filho, Antônio M Cruz

2010-01-01

The purpose of this investigation was to evaluate the physicochemical properties of gray and white structural and nonstructural Portland cement, gray and white ProRoot MTA and MTA BIO. The water/powder ratio, setting time, solubility and pH (hydrogen-ion potential) changes of the materials were evaluated. Tests followed specification #57 from the American National Standard Institute/American Dental Association (2000) for endodontic sealing materials and pH was determined by a digital pH meter. The test results were statistically analyzed by variance analyses for global comparison and by the complementary Tukey's test for pairwise comparisons (5%). Considering the water/powder ratio, no significant difference (p > 0.05) was observed among the cements. MTA BIO (33.10 +/- 2.30) had the lowest setting time (p Portland cement (2.55 +/- 0.08) had the highest solubility (p 0.05) was observed among materials when considering pH evaluation. The pH levels were highly alkaline immediately after immersion in solution, remaining stable throughout the test period. The authors conclude that the cements had similar water/powder proportions. MTA BIO had the shortest setting time and gray ProRoot MTA had the lowest solubility. All cements had similar behavior in the pH analysis.

STABILISASI TANAH LIAT SANGAT LUNAK DENGAN GARAM DAN PC (PORTLAND CEMENT

Directory of Open Access Journals (Sweden)

Tirta Djusman Arief

2006-01-01

Full Text Available Adding sodium chloride, as admixture, and Portland Cement, as stabilizer, to a very soft clay increase its plasticity index (PI, Californian Bearing Ratio (CBR, and Unconfined Compression Strength (UCS. This paper presents the results of testings done to very soft clay from Margomulyo, Surabaya. The results show a promising tendency. Anyhow a wider and comprehensive research is still needed to ensure the long-term effect of the soil stabilization. Abstract in Bahasa Indonesia : Penambahan garam (sodium chloride dan PC (Portland Cement meningkatkan PI (Plasticity Index, CBR (Californian Bearing Ratio, dan UCS (Unconfined Compression Strength dari tanah lempung sangat lunak. Dalam makalah ini disajikan hasil pengujian yang dilakukan terhadap lempung sangat lunak dari daerah Margomulyo, Surabaya. Hasilnya menunjukkan kecenderungan yang menggembirakan, namun penelitian yang luas dan komprehensif masih diperlukan untuk peningkatan stabilitas tanah dalam jangka panjang.

Ex vivo assessment of genotoxicity and cytotoxicity in murine fibroblasts exposed to white MTA or white Portland cement with 15% bismuth oxide.

Science.gov (United States)

Zeferino, E G; Bueno, C E S; Oyama, L M; Ribeiro, D A

2010-10-01

To evaluate whether white mineral trioxide aggregate (MTA) or white Portland cement with 15% bismuth oxide were able to induce genetic damage and cellular death ex vivo. Aliquots of 1 × 10(4) murine fibroblasts were incubated at 37 °C for 3 h with MTA (white) or white Portland cement with 15% bismuth oxide, at final concentrations ranging from 10 to 1000 μg mL(-1) individually. Data of three independent repeats from the comet assay and the trypan blue exclusion test were assessed by the one-way anova followed by Tukey's test. Mineral trioxide aggregate or Portland cement containing bismuth oxide did not produce genotoxic effects with respect to the single-cell gel (comet) assay data for all concentrations evaluated. Furthermore, no cytotoxicity was observed for MTA or Portland cement. White MTA or white Portland cement containing 15% bismuth oxide were not genotoxic and cytotoxic. © 2010 International Endodontic Journal.

The biomineralization ability of mineral trioxide aggregate and Portland cement on dentin enhances the push-out strength.

Science.gov (United States)

Reyes-Carmona, Jessie F; Felippe, Mara S; Felippe, Wilson T

2010-02-01

Recently, it was shown that the interaction of each of mineral trioxide aggregate (MTA) and Portland cement with dentin in phosphate-buffered saline (PBS) promotes a biomineralization process that leads to the formation of an interfacial layer with tag-like structures at the cement-dentin interface. This study analyzes the influence of the biomineralization process on the push-out strength of ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK), MTA Branco (Angelus Soluções Odontológicas, Londrina, PR, Brazil), MTA BIO (Angelus Soluções Odontológicas), or Portland cement with and without calcium chloride. Dentin discs with standardized cavities were filled with ProRoot MTA, MTA Branco, MTA BIO, white Portland cement + 20% bismuth oxide (PC1), or PC1 + 10% of calcium chloride (PC2). The specimens were randomly divided into two groups: cement in contact with a wet cotton pellet for 72 hours or immersed in PBS for 2 months. The bond strengths were measured with the Instron Testing machine (Model 4444; Instron Corp, Canton, MA), and the fractured surfaces on the root walls were observed by scanning electron microscopy. All samples immersed in PBS displayed a significantly greater resistance to displacement than that observed for the samples in contact with a wet cotton pellet for 72 hours (p Portland cements. It was concluded that the biomineralization process positively influenced the push-out bond strength of the cements, particularly the MTA groups. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

The Influence of Diatomite on the Strength and Microstructure of Portland Cement

OpenAIRE

Liu Jun; Shao Peng; Wang Shihao

2016-01-01

To study the influence of the types and mixing amount of diatomite on the Portland cement, we prepared the cement specimen doped with the calcined first-grade, first-grade and second-grade diatomite ,tested the 3d, 7d, 14d compressive strength, and studied and discussed phase, structure and morphology of diatomite in the binary system by the method of XRD, SEM . Experimental results show that with the addition of diatomite, the strength of cement paste increase; the optimal contents of calcin...

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

DEFF Research Database (Denmark)

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

2009-01-01

The applicability, reliability, and repeatability of 29Si MAS NMR for determination of the quantities of alite (Ca3SiO5) and belite (Ca2SiO4) in anhydrous Portland cement was investigated in detail for 11 commercial Portland cements and the results compared with phase quantifications based...

Biological evaluation of a new pulp capping material developed from Portland cement.

Science.gov (United States)

Negm, Ahmed M; Hassanien, Ehab E; Abu-Seida, Ashraf M; Nagy, Mohamed M

2017-03-02

This study evaluates the biological properties of a new pulp capping material developed from Portland cement. This study was conducted on 48 teeth in 4 dogs (12 teeth/dog). The dogs were classified into two equal groups (n=24 teeth) according to the evaluation period including: group A (3 weeks) and group B (3 months). Each group was further subdivided into three equal subgroups (n=8 teeth) according to the capping material including: subgroup 1: mineral trioxide aggregate (MTA), subgroup2: Portland cement+10% calcium hydroxide+20% bismuth oxide (Port Cal) and subgroup 3: Portland cement+bismuth oxide. After general anesthesia, a class V buccal cavity was prepared coronal to the gingival margin. After pulp exposure and hemostasis,the capping materials and glass ionomer filling were placed on the exposure sites. All histopathological findings, inflammatory cell count and dentin bridge formation were recorded. Data were analyzed statistically. After 3 months, the histopathological picture of the pulp in subgroup 1 showed normal pulp, continuous odontoblastic layer and complete dentin bridge formation while subgroup 2 showed partial and complete dentin bridge over a normal and necrotic pulps. Subgroup 3 showed loss of normal architecture, areas of necrosis, complete, or incomplete dentin bridge formation, attached and detached pulp stones and fatty degeneration in group B. For group A, MTA subgroup showed the least number of inflammatory cell infiltrate followed by Port Cal subgroup. While subgroup 3 showed the highest number of inflammatory cell infiltrate. For group B, the mean inflammatory cell count increased with the three tested materials with no statistical difference. Regarding dentin bridge formation at group A, no significant differences was found between subgroups, while at group B, MTA subgroup exhibited significantly higher scores than other subgroups. In conclusion, addition of calcium hydroxide to Portland cement improves the dentin bridge formation

Effects of chemical and mineral additives and the water/cement ratio on the thermal resistance of Portland cement concrete

International Nuclear Information System (INIS)

Cesar, Leandro Cesar Dias; Morelli, Arnaldo C.; Baldo, Joao Baptista

1998-01-01

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

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

Directory of Open Access Journals (Sweden)

João de Farias Filho

2000-12-01

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

Immobilization of citric acid solutions in portland cement

International Nuclear Information System (INIS)

Lopes, Valdir M.; Rzyski, Barbara M.

1997-01-01

Decontamination processes by using citric acid on certain items used in the nuclear area, can result in large volumes of liquid wastes with low activity or effluents, contaminated with uranium and some elements dangerous to the environment. A great number of installations that have decontamination processes adopt the zero discharge philosophy. So, one of the forms to isolate the solutions is by reducing its volume through the evaporation process. The generated must can be neutralized and encapsulated or immobilized in Portland cement. This work propose a chemical technique to destroy the citric acid in the decontamination solutions instead of neutralization and, depending on the installation convenience, a direct cement immobilization of these solutions or of the evaporation mud. The results obtained in this work involve data about the workability, setting time and mechanical resistance, after 28 days of sealed cure, for samples with water-cement ratios of 4, 0.5 and 0.6, by weight. (author). 5 refs., 2 tabs

Partial replacement of Portland cement by red ceramic waste in mortars: study of pozzolanic activity; Substituicao parcial do cimento Portland por residuo de ceramica vermelha em argamassas: estudo da atividade pozolonica

Energy Technology Data Exchange (ETDEWEB)

Silva, A.R. da; Cabral, K.C.; Pinto, E.N. de M.G.l., E-mail: kleber.cabral@ufersa.edu.br [Universidade Federal Rural do Semi-Arido (UFERSA), Mossoro, RN (Brazil)

2016-07-01

The objective of this study is to analyze the pozzolanic activity of red ceramic residue on the partial replacement of Portland cement in mortars. The mortars were prepared by substituting 25% of the Portland cement for ground of ceramic residue with water cement’s factor of 0.48. The concrete used to construct the reference mortars and those with addiction was CPII-Z-32 (compound of Portland pozzolana cement). The chemical analysis and physical ceramic waste showed that this meets the requirements of NBR12653 (2014) for use as pozzolanic material. The pozzolanic activity index (IAP) obtained for the ceramic waste to twenty-eight days cure rate was 80.28%. (author)

Peach leaf responses to soil and cement dust pollution.

Science.gov (United States)

Maletsika, Persefoni A; Nanos, George D; Stavroulakis, George G

2015-10-01

Dust pollution can negatively affect plant productivity in hot, dry and with high irradiance areas during summer. Soil or cement dust were applied on peach trees growing in a Mediterranean area with the above climatic characteristics. Soil and cement dust accumulation onto the leaves decreased the photosynthetically active radiation (PAR) available to the leaves without causing any shade effect. Soil and mainly cement dust deposition onto the leaves decreased stomatal conductance, photosynthetic and transpiration rates, and water use efficiency due possibly to stomatal blockage and other leaf cellular effects. In early autumn, rain events removed soil dust and leaf functions partly recovered, while cement dust created a crust partially remaining onto the leaves and causing more permanent stress. Leaf characteristics were differentially affected by the two dusts studied due to their different hydraulic properties. Leaf total chlorophyll decreased and total phenol content increased with dust accumulation late in the summer compared to control leaves due to intense oxidative stress. The two dusts did not cause serious metal imbalances to the leaves, except of lower leaf K content.

Corneal permeability for cement dust: prognosis for occupational safety

Science.gov (United States)

Kalmykov, R. V.; Popova, D. V.; Kamenskikh, T. G.; Genina, E. A.; Tuchin, V. V.; Bashkatov, A. N.

2018-02-01

The high dust content in air of a working zone causes prevalence of pathologies of the anterior segment of the eye of workers of cement production. Therefore, studying of features of cement dust impact on structure of a cornea and development of ways of eye protection from this influence is relevant. In this work experimental studies were carried out with twenty eyes of ten rabbits. OCTtomography was used to monitor the light attenuation coefficient of the cornea in vitro during the permeability of cement dust and/or keratoprotector (Systein Ultra). The permeability coefficients of the cornea for water, cement dust and keratoprotector were measured. A computer model allowing one to analyze the diffusion of these substances in the eye cornea was developed. It was shown that 1) the cement dust falling on the eye cornea caused pronounced dehydration of the tissue (thickness decreasing) and led to the increase of the attenuation coefficient, which could affect the deterioration of the eyesight of workers in the conditions of cement production; 2) the application of the keratoprotector to the eye cornea when exposed by cement dust, slowed significantly the dehydration process and did not cause the increase of the attenuation coefficient that characterized the stabilization of visual functions. At this, the keratoprotector itself did not cause dehydration and led to the decrease of the attenuation coefficient, which could allow it to be used for a long time in the order to protect the organ of vision from the negative effects of cement dust.

Final Rule: NESHAP for the Portland Cement Manufacturing Industry: Alternative Monitoring Method

Science.gov (United States)

EPA is extending its approval for the use of an alternative method to show compliance with hydrogen chloride (HCl) emissions limits in the National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing Industry

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

International Nuclear Information System (INIS)

Rosa Junior, A.A.

1988-01-01

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)

Influence of moisture condition on chloride diffusion in partially saturated ordinary Portland cement mortar

NARCIS (Netherlands)

Zhang, Y.; Zhang, M.; Ye, G.

2018-01-01

Experiments have been carried out to study the influence of moisture condition, including moisture content and its distribution, on the chloride diffusion in partially saturated ordinary Portland cement mortar. The mortar samples with water-to-cement (w/c) ratios of 0.4, 0.5 and 0.6, cured for 1

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

Science.gov (United States)

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

2015-01-01

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

Comparative Study of Portland Cement-based and Zeolite-based Concretes in Terms of Hexavalent Chromium Leaching

Directory of Open Access Journals (Sweden)

Oravec Jozef

2016-12-01

Full Text Available The paper presents the results of the leaching study of Portland cement-based and zeolite-based concretes regarding water soluble hexavalent chromium. Three leaching water media (distilled water, rain water, and Britton-Robinson buffer of various pH values were under investigation. The correlation between pH and leached-out concentrations of chromium was not confirmed. The content of hexavalent water-soluble chromium in leachates of zeolite-based concretes was found to be higher than that in leachates of Portland cement-based samples.

Experimental Study on Artificial Cemented Sand Prepared with Ordinary Portland Cement with Different Contents

Directory of Open Access Journals (Sweden)

Dongliang Li

2015-07-01

Full Text Available Artificial cemented sand test samples were prepared by using ordinary Portland cement (OPC as the cementing agent. Through uniaxial compression tests and consolidated drained triaxial compression tests, the stress-strain curves of the artificial cemented sand with different cementing agent contents (0.01, 0.03, 0.05 and 0.08 under various confining pressures (0.00 MPa, 0.25 MPa, 0.50 MPa and 1.00 MPa were obtained. Based on the test results, the effect of the cementing agent content (Cv on the physical and mechanical properties of the artificial cemented sand were analyzed and the Mohr-Coulomb strength theory was modified by using Cv. The research reveals that when Cv is high (e.g., Cv = 0.03, 0.05 or 0.08, the stress-strain curves of the samples indicate a strain softening behavior; under the same confining pressure, as Cv increases, both the peak strength and residual strength of the samples show a significant increase. When Cv is low (e.g., Cv = 0.01, the stress-strain curves of the samples indicate strain hardening behavior. From the test data, a function of Cv (the cementing agent content with c′ (the cohesion force of the sample and Δϕ′ (the increment of the angle of shearing resistance is obtained. Furthermore, through modification of the Mohr-Coulomb strength theory, the effect of cementing agent content on the strength of the cemented sand is demonstrated.

Experimental Study on Artificial Cemented Sand Prepared with Ordinary Portland Cement with Different Contents.

Science.gov (United States)

Li, Dongliang; Liu, Xinrong; Liu, Xianshan

2015-07-02

Artificial cemented sand test samples were prepared by using ordinary Portland cement (OPC) as the cementing agent. Through uniaxial compression tests and consolidated drained triaxial compression tests, the stress-strain curves of the artificial cemented sand with different cementing agent contents (0.01, 0.03, 0.05 and 0.08) under various confining pressures (0.00 MPa, 0.25 MPa, 0.50 MPa and 1.00 MPa) were obtained. Based on the test results, the effect of the cementing agent content ( C v ) on the physical and mechanical properties of the artificial cemented sand were analyzed and the Mohr-Coulomb strength theory was modified by using C v . The research reveals that when C v is high (e.g., C v = 0.03, 0.05 or 0.08), the stress-strain curves of the samples indicate a strain softening behavior; under the same confining pressure, as C v increases, both the peak strength and residual strength of the samples show a significant increase. When C v is low (e.g., C v = 0.01), the stress-strain curves of the samples indicate strain hardening behavior. From the test data, a function of C v (the cementing agent content) with c ' (the cohesion force of the sample) and Δϕ' (the increment of the angle of shearing resistance) is obtained. Furthermore, through modification of the Mohr-Coulomb strength theory, the effect of cementing agent content on the strength of the cemented sand is demonstrated.

Portland cement concrete pavement review of QC/QA data 2000 through 2009.

Science.gov (United States)

2011-04-01

This report analyzes the Quality Control/Quality Assurance (QC/QA) data for Portland cement concrete pavement : (PCCP) awarded in the years 2000 through 2009. Analysis of the overall performance of the projects is accomplished by : reviewing the Calc...

Recycled Portland cement concrete pavements : Part II, state-of-the art summary.

Science.gov (United States)

1979-01-01

This report constitutes a review of the literature concerning recycling of portland cement concrete pavements by crushing the old pavement and reusing the crushed material as aggregate in a number of applications. A summary of the major projects cond...

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

Energy Technology Data Exchange (ETDEWEB)

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

2004-07-01

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

Study on the alternative mitigation of cement dust spread by capturing the dust with fogging method

Science.gov (United States)

Purwanta, Jaka; Marnoto, Tjukup; Setyono, Prabang; Handono Ramelan, Ari

2017-12-01

The existence of a cement plant impact the lives of people around the factory site. For example the air quality, which is polluted by dust. Cement plant has made various efforts to mitigate the generated dust, but there are still alot of dust fly inground either from the cement factory chimneys or transportation. The purpose of this study was to conduct a review of alternative mitigation of the spread of dust around the cement plant. This study uses research methods such as collecting secondary data which includes data of rain density, the average rains duration, wind speed and direction as well as data of dust intensity quality around PT. Semen Gresik (Persero) Tbk.Tuban plant. A soft Wind rose file is used To determine the wind direction propensity models. The impact on the spread of dust into the environment is determined using secondary data monitoring air quality. Results of the study is that the mitigation of dust around the cement plant is influenced by natural factors, such as the tendency of wind direction, rain fall and rainy days, and the rate of dust emission from the chimney. The alternative means proposed is an environmental friendly fogging dust catcher.

Quantitative study of Portland cement hydration by X-Ray diffraction/Rietveld analysis and geochemical modeling

Science.gov (United States)

Coutelot, F.; Seaman, J. C.; Simner, S.

2017-12-01

In this study the hydration of Portland cements containing blast-furnace slag and type V fly ash were investigated during cement curing using X-ray diffraction, with geochemical modeling used to calculate the total volume of hydrates. The goal was to evaluate the relationship between the starting component levels and the hydrate assemblages that develop during the curing process. Blast furnace-slag levels of 60, 45 and 30 wt.% were studied in blends containing fly ash and Portland cement. Geochemical modelling described the dissolution of the clinker, and predicted quantitatively the amount of hydrates. In all cases the experiments showed the presence of C-S-H, portlandite and ettringite. The quantities of ettringite, portlandite and the amorphous phases as determined by XRD agreed well with the calculated amounts of these phases after different periods of time. These findings show that changes in the bulk composition of hydrating cements can be described by geochemical models. Such a comparison between experimental and modelled data helps to understand in more detail the active processes occurring during cement hydration.

Portland blended cements: demolition ceramic waste management

International Nuclear Information System (INIS)

Trezza, M.A.; Zito, S.; Tironi, A.; Irassar, E.F.; Rahhal, V.F.

2017-01-01

Demolition ceramic wastes (DCWs) were investigated in order to determine their potential use as supplementary cementitious materials in Portland Blended Cements (PBCs). For this purpose, three ceramic wastes were investigated. After characterization of the materials used, the effect of ceramic waste replacement (8, 24 and 40% by mass) was analyzed. Pozzolanic activity, hydration progress, workability and compressive strength were determined at 2, 7 and 28 days. The results showed that the ground wastes behave as filler at an early age, but as hydration progresses, the pozzolanic activity of ceramic waste contributes to the strength requirement. [es

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

Science.gov (United States)

Marciano, Marina Angélica; Garcia, Roberto Brandão; Cavenago, Bruno Cavalini; Minotti, Paloma Gagliardi; Midena, Raquel Zanin; Guimarães, Bruno Martini; Ordinola-Zapata, Ronald; Duarte, Marco Antonio Hungaro

2014-01-01

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. 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 (pPortland 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.

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.

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

International Nuclear Information System (INIS)

Zalina Laili; Mohd Abdul Wahab; Nur Azna Mahmud

2014-01-01

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)

X-ray diffractometry of steam cured ordinary Portland and blast-furnace-slag cements; Difratometria de raios X de pastas de cimento Portland comum e de alto-forno submetidas a cura termica

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Camarini, G [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia; Djanikian, J G [Sao Paulo Univ., SP (Brazil). Escola Politecnica

1994-12-31

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 95{sup 0} 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.

Evaluation of dynamic elasticity module in samples of Portland (type 1) cement paste exposed to neutronic irradiation

International Nuclear Information System (INIS)

Rosa Junior, A.A.; Lucki, G.

1986-01-01

The fast neutron radiation effects and temperature on Portland cement are studied. The Dynamic Elasticity Module (Ed) in samples of Portland cement paste was evaluated. Ultrassonic technics were applied (resonance frequency and pulse velocity). The samples were irradiated with fast neutrons to fluence of 7,2 x 10 18 n/cm 2 (E approx. 1 MeV), at temperature of 120 + - 5 0 C, due to gamma heating. This temperature was simulated in laboratory in a microwave oven. (Author) [pt

Mineral Trioxide Aggregate and Portland Cement for Direct Pulp Capping in Dog: A Histopathological Evaluation

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Maryam Bidar

2014-09-01

Full Text Available Background and aims. Mineral trioxide aggregate and calcium hydroxide are considered the gold standard pulp-capping materials. Recently, Portland cement has been introduced with properties similar to those of mineral trioxide aggregate. His-topathological effects of direct pulp capping using mineral trioxide aggregate and Portland cements on dog dental pulp tis-sue were evaluated in the present study. Materials and methods. This histopatological study was carried out on 64 dog premolars. First, the pulp was exposedwith a sterile bur. Then, the exposed pulp was capped with white or gray mineral trioxide aggregates and white or gray Port-land cements in each quadrant and sealed with glass-ionomer. The specimens were evaluated under a light microscope after 6 months. Statistical analysis was carried out using Kruskal-Wallis test. Statistical significance was defined at α=5%. Results. There was no acute inflammation in any of the specimens. Chronic inflammation in white and gray mineral triox-ide aggregates and white and gray Portland cements was reported to be 45.5%, 27.3%, 57.1% and 34.1%, respectively. Al-though the differences were not statistically significant, severe inflammation was observed mostly adjacent to white mineral trioxide aggregate. The largest extent of increased vascularization (45% and the least increase in fibrous tissue were ob-served adjacent to white mineral trioxide aggregate, with no significant differences. In addition, the least calcified tissue formed adjacent to white mineral trioxide aggregate, although the difference was not significant. Conclusion. The materials used in this study were equally effective as pulp protection materials following direct pulp cap-ping in dog teeth.

Determination of the leaching rate of radionuclide 134Cs from the solidified radioactive wastes in Syrian Portland cement and cement-microsilica matrixes

International Nuclear Information System (INIS)

Ismail Shaaban; Nasim Assi

2010-01-01

The suitability of Syrian Portland cement for disposal of solidified low-level radioactive waste was assessed by measuring the leaching rate of 134 Cs. In ordinary cement concrete, a leaching rate of 1.309 x 10 -3 g/cm 2 per day was measured. Mixing this concrete with microsilica reduced significantly the leaching rate to 3.106 x 10 -4 g/cm 2 per day for 1% mixing, and to 9.645 x 10 -5 g/cm 2 per day for 3% mixing. It was also found that the application of a latex paint reduced these leaching rates by about 10%. These results, along with mechanical strength tests (under radiation exposure, high temperature, long water immersion and freeze-thaw cycling) indicate that Syrian Portland cement is suited for the disposal of low-level radioactive waste. (author)

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

International Nuclear Information System (INIS)

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

2017-01-01

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

Development of Mix Design Method in Efforts to Increase Concrete Performance Using Portland Pozzolana Cement (PPC)

Science.gov (United States)

Krisnamurti; Soehardjono, A.; Zacoeb, A.; Wibowo, A.

2018-01-01

Earthquake disaster can cause infrastructure damage. Prevention of human casualties from disasters should do. Prevention efforts can do through improving the mechanical performance of building materials. To achieve high-performance concrete (HPC), usually used Ordinary Portland Cement (OPC). However, the most widely circulating cement types today are Portland Pozzolana Cement (PPC) or Portland Composite Cement (PCC). Therefore, the proportion of materials used in the HPC mix design needs to adjust to achieve the expected performance. This study aims to develop a concrete mix design method using PPC to fulfil the criteria of HPC. The study refers to the code/regulation of concrete mixtures that use OPC based on the results of laboratory testing. This research uses PPC material, gravel from Malang area, Lumajang sand, water, silica fume and superplasticizer of a polycarboxylate copolymer. The analyzed information includes the investigation results of aggregate properties, concrete mixed composition, water-binder ratio variation, specimen dimension, compressive strength and elasticity modulus of the specimen. The test results show that the concrete compressive strength achieves value between 25 MPa to 55 MPa. The mix design method that has developed can simplify the process of concrete mix design using PPC to achieve the certain desired performance of concrete.

NESHAP for the Portland Cement Manufacturing Industry: Fact Sheets for Actions Since 2015

Science.gov (United States)

EPA is extending its approval for the use of an alternative method to show compliance with hydrogen chloride (HCl) emissions limits in the National Emission Standards for Hazardous Air Pollutants for the Portland Cement Manufacturing Industry

Measurement of the leaching rate of radionuclide 134Cs from the solidified radioactive sources in Portland cement mixed with microsilica and barite matrixes

International Nuclear Information System (INIS)

Shaaban, Ismail; Assi, Nasim

2011-01-01

Portland cement was mixed with radionuclide 134 Cs to produce low-level radioactive sources. These sources were surrounded with cement mixed with different materials like microsilica and barite. The leaching rate of 134 Cs from the solidified radioactive source in Portland cement alone was found to be 4.481 x 10 -4 g/cm 2 per day. Mixing this Portland cement with microsilica and with barite reduced significantly the leaching rate to 1.091 x 10 -4 g/cm 2 per day and 3.153 x 10 -4 g/cm 2 per day for 1 wt.% mixing, and to 1.401 x 10 -5 g/cm 2 per day and 1.703 x 10 -4 g/cm 2 per day for 3 wt.% mixing, respectively. It was also found that the application of a latex paint reduced these leaching rates by about 6.5%, 20.3% and 13.3% for Portland cement, cement mixed with microsilica and with barite, respectively. The leaching data were also analyzed using the polynomial method. The obtained results showed that cement mixed with microsilica and with barite can be effectively used for radioactive sources solidification.

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

International Nuclear Information System (INIS)

Coleman, Nichola J.; Li, Qiu

2013-01-01

Zirconium oxide has been identified as a candidate radiopacifying agent for use in Portland cement-based biomaterials. During this study, the impact of 20 wt.% zirconium oxide on the hydration and setting reactions of white Portland cement (WPC) was monitored by powder X-ray diffraction (XRD), 29 Si and 27 Al magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), transmission electron microscopy (TEM) and Vicat apparatus. The presence of 20 wt.% zirconium oxide particles in the size-range of 0.2 to 5 μm was found to reduce the initial and final setting times of WPC from 172 to 147 min and 213 to 191 min, respectively. Zirconium oxide did not formally participate in the chemical reactions of the hydrating cement; however, the surface of the zirconium oxide particles presented heterogeneous nucleation sites for the precipitation and growth of the early C-S-H gel products which accelerated the initial setting reactions. The presence of zirconium oxide was found to have little impact on the development of the calcium (sulpho)aluminate hydrate phases. - Highlights: ► This is the first study of Portland cement-based biomaterials by 27 Al and 29 Si NMR. ► 20 wt.% ZrO 2 radiopacifier accelerates the early cement hydration reactions. ► Extent of hydration after 6 h is increased from 5.7% to 15% in the presence of ZrO 2 . ► Initial and final setting times are reduced by 25 and 22 min, respectively. ► ZrO 2 provides nucleation sites for the precipitation of early hydration products.

Hydration of Portland cement with additions of calcium sulfoaluminates

International Nuclear Information System (INIS)

Le Saoût, Gwenn; Lothenbach, Barbara; Hori, Akihiro; Higuchi, Takayuki; Winnefeld, Frank

2013-01-01

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.

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.

Utilization of the national Portland cement for immobilizing radioactive wastes - Physical characteristics

International Nuclear Information System (INIS)

Rzyski, B.M.; Suarez, A.A.

1988-01-01

This paper shows the results obtained in the study of the national Portland cement, P320, as matrix for radioactive nitric waste incorporation. Cement use practice in other countries is common for this purposes and demonstrates to be cheap and accessible when low and medium level wastes are immobilized. Some of physical characteristics as: homogeneity,mechanical strenght, setting and porosity are analysed due to water-cement ratio and salt contents. Those characteristics which are proper of the final product, must be controlled in such way to assure a long time integrity of the wasteform. The establishment of process and quality control criteria are based in such kind of data. (author) [pt

Achievement of 900kgf/cm[sup 2] super workable high strength concrete with belite portland cement. (elevator building of cement silo in Chichibu cement). Part 1. ; Development of cement for super workable high strength concrete. Ko belite kei cement de 900kgf/cm[sup 2] wo tassei (Chichibu cement cement sairo no elevaor to). 1. ; Koryudo kokyodo concrete yo no cement no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Tanaka, M.; Fukaya, Y.; Nawa, T. (Chichibu Cement Co. Ltd., Tokyo (Japan))

1993-08-01

This paper describes the features of high belite Portland cement which can make the super workable high strength concrete, and the properties of concrete using this. The super workable concrete is required an excellent segregation resistance property as well as high flow property. Since the high belite Portland cement contains a small amount of C[sub 3]S in the clinker, the amounts of C[sub 3]A and C[sub 4]AF can be reduced without hindering the calcination of clinker. Additionally, since it contains a large amount of C[sub 2]S with low heat of hydration, an increase in the temperature of members can be suppressed. 'Chichibu High Flow Cement' having characteristics of this high belite Portland cement was developed for the super workable high strength concrete. The concrete using the High Flow Cement exhibited the maximum flow value of 70cm. It also exhibited the strength of 1,075 kgf/cm[sup 2] at the age of 91 days, and 1,100 kgf/cm[sup 2] at the age of 14 days under insulating. 4 refs., 8 figs., 2 tabs.

Influence of Ba2+ and Sr2+ ions on the hydration process of portland cement and blended cements

Directory of Open Access Journals (Sweden)

Živanović, B. M.

1987-12-01

Full Text Available This study concerns the influence of the concentration of Sr2+ and Ba2+ ions in mortar batch waters upon the hydration process of various Portland and additive cements. An increase in the mechanical resistence of said cements is observed, after 28 days, when the concentration of Ba2+ and Sr2+ ions in the mortar batch waters increases. This suggests a possible microstructural explanation of said phenomenon.En el presente trabajo se estudia la influencia de la concentración de los iones Sr2+ y Ba2+ en las aguas de amasado sobre el proceso de hidratación de varios cementos portland y de adición. Se comprueba un incremento de las resistencias mecánicas de dichos cementos, a los 28 días, cuando aumenta la concentración de los iones Ba2+ y Sr2+ en las aguas de amasado, lo cual sugiere una posible explicación microestructural a dicho fenómeno.

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

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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.

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.

Phased-Resolved Strain Measuremetns in Hydrated Ordinary Portland Cement Using Synchrotron x-Rays (Prop. 2003-033)

International Nuclear Information System (INIS)

Biernacki, Joseph J.; Watkins, Thomas R.; Parnham, C.J.; Hubbard, Camden R.; Bai, J.

2006-01-01

X-ray diffraction methods developed for the determination of residual stress states in crystalline materials have been applied to study residual strains and strains because of mechanical loading of ordinary portland cement paste. Synchrotron X-rays were used to make in situ measurements of interplanar spacings in the calcium hydroxide (CH) phase of hydrated neat portland cement under uniaxial compression. The results indicate that strains on the order of 1/100 000 can be resolved providing an essentially new technique by which to measure the phase-resolved meso-scale mechanical behavior of cement under different loading conditions. Evaluation of these strain data in view of published elastic parameters for CH suggests that the CH carries a large fraction of the applied stress and that plastic interactions with the matrix are notable.

Effect of silica fume on reaction products of uranium (VI) with portland cement

International Nuclear Information System (INIS)

Tan Hongbin; Shaanxi Univ. of Technology, Hanzhong; Li Yuxiang

2005-01-01

Simulation of radioactive waste of U(VI) by uranyl nitrate and the effects of different additive quantities (12%, 20%, 30%, 35%, 40%) of silica fume on the products of U(VI) with Portland cement were studied at a hydrothermal condition of 180 degree C for a duration of one week. The X-ray powder diffraction examination results showed that the calcium uranate would be transformed into uranophane when the cement contained 30% silica fume. (authors)

Flow properties of MK-based geopolymer pastes. A comparative study with standard Portland cement pastes.

Science.gov (United States)

Favier, Aurélie; Hot, Julie; Habert, Guillaume; Roussel, Nicolas; d'Espinose de Lacaillerie, Jean-Baptiste

2014-02-28

Geopolymers are presented in many studies as alternatives to ordinary Portland cement. Previous studies have focused on their chemical and mechanical properties, their microstructures and their potential applications, but very few have focussed on their rheological behaviour. Our work highlights the fundamental differences in the flow properties, which exist between geopolymers made from metakaolin and Ordinary Portland Cement (OPC). We show that colloidal interactions between metakaolin particles are negligible and that hydrodynamic effects control the rheological behaviour. Metakaolin-based geopolymers can then be described as Newtonian fluids with the viscosity controlled mainly by the high viscosity of the suspending alkaline silicate solution and not by the contribution of direct contacts between metakaolin grains. This fundamental difference between geopolymers and OPC implies that developments made in cement technology to improve rheological behaviour such as plasticizers will not be efficient for geopolymers and that new research directions need to be explored.

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

Energy Technology Data Exchange (ETDEWEB)

Lafond, E. [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze cedex (France); Cau dit Coumes, C., E-mail: celine.cau-dit-coumes@cea.fr [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze cedex (France); Gauffinet, S. [Laboratoire Interdisciplinaire Carnot de Bourgogne UMR 6303 CNRS-Université de Bourgogne, Dijon, France, 9 Av Alain Savary, BP 47870, 21078 Dijon cedex (France); Chartier, D. [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze cedex (France); Stefan, L. [AREVA, Back End Business Group, Dismantling & Services, 1 Place Jean Millier, 92084 Paris La Défense (France); Le Bescop, P. [CEA, DEN, DPC, SECR, F-91192 Gif-sur-Yvette (France)

2017-01-15

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

Personal exposure to inhalable cement dust among construction workers.

NARCIS (Netherlands)

Peters, S.M.; Thomassen, Y.; Fechter-Rink, E.; Kromhout, H.

2009-01-01

Objective- A case study was carried out to assess cement dust exposure and its determinants among construction workers and for comparison among workers in cement and concrete production.Methods- Full-shift personal exposure measurements were performed and samples were analysed for inhalable dust and

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

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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.

Physicochemical and mechanical properties of zirconium oxide and niobium oxide modified Portland cement-based experimental endodontic sealers.

Science.gov (United States)

Viapiana, R; Flumignan, D L; Guerreiro-Tanomaru, J M; Camilleri, J; Tanomaru-Filho, M

2014-05-01

To evaluate the physicochemical and mechanical properties of Portland cement-based experimental sealers (ES) with different radiopacifying agents (zirconium oxide and niobium oxide micro- and nanoparticles) in comparison with the following conventional sealers: AH Plus, MTA Fillapex and Sealapex. The materials were tested for setting time, compressive strength, flow, film thickness, radiopacity, solubility, dimensional stability and formaldehyde release. Data were subjected to anova and Tukey tests (P 0.05) and lower solubility when compared with MTA Fillapex and Sealapex (P Portland cement-based experimental endodontic sealers presented physicochemical properties according to the specifications no 57 ANSI/ADA (ADA Professional Product Review, 2008) and ISO 6876 (Dentistry - Root Canal Sealing Materials, 2012, British Standards Institution, London, UK). The sealers had setting times and flow ability that was adequate for clinical use, satisfactory compressive strength and low solubility. Additional studies should be carried out with the purpose of decreasing the film thickness and to determine the ideal ratio of radiopacifying agents in Portland cement-based root canal sealers. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

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 alite...

Experimental investigation of the multiple scatter peak of gamma rays in portland cement in the energy range 279-1332 keV

International Nuclear Information System (INIS)

Singh, Tejbir; Singh, Parjit S

2011-01-01

The pulse height spectra for different thicknesses of portland cement in the reflected geometry has been recorded with the help of a NaI(Tl) scintillator detector and 2 K MCA card using different gamma-ray sources such as Hg 203 (279 keV), Cs 137 (662 keV) and Co 60 (1173 and 1332 keV). It has been observed that the multiple scatter peak for portland cement appears at 110 (±7) keV in all the spectra irrespective of different incident photon energies in the range 279-1332 keV from different gamma-ray sources. Further, the variation in the intensity of the multiple scatter peak with the thickness of portland cement in the backward semi-cylinders has been investigated.

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

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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

Determination of coefficient of thermal expansion for Portland Cement Concrete pavements for MEPDG Implementation

Science.gov (United States)

2012-10-01

The Coefficient of Thermal Expansion (CTE) is an important parameter in Portland Cement Concrete (PCC) pavement analysis and design as it is directly proportional to the magnitude of temperature-related pavement deformations throughout the pavement s...

Effect of three natural pozzolans in portland cement hydration

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Rahhal, V.

2003-03-01

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

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

41 CFR 50-204.50 - Gases, vapors, fumes, dusts, and mists.

Science.gov (United States)

2010-07-01

... Soapstone 20 Talc 20 Portland cement 50 Graphite (natural) 15 Coat dust (respirable fraction less than 5% Si...-selector with the following characteristics: Aerodynamic diameter (unit density sphere) Percent passing...

Effect of cement production on vegetation in a part of southwestern ...

African Journals Online (AJOL)

The impact of cement dust emissions from the factory of West African Portland Cement at Ewekoro in Southwestern Nigeria on the surrounding vegetation was investigated. Sample plots of 20 m x 20 m were established at 1 km intervals from the factory site up to a distance of 10 km intervals from the factory site up to a ...

Analysis by X-Ray images of wind blandes waste incorporated in Portland cement

International Nuclear Information System (INIS)

Marques, M.A.

2011-01-01

The wind blandes wastes can be reused in the incorporation in Portland cement, to be used in non-structural constructions. This work shows 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 mass relation of sand, pebbles and cement was 3:2:1 and 10%, 20% and 50% of waste was incorporated in cement specimens. Frontal and upper projections were obtained in X-Rays images. 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)

Preparation of iron-modified portland cement adsorbent and the investigation of its decolorization performance

Science.gov (United States)

Jiang, Bo; Wang, Huifeng; Li, Yang; Li, Zhen

2018-02-01

The ordinary portland cement was modified by ferric salt impregnation method. Through the technologies of x-ray diffraction, scanning electron microscope and energy dispersive spectroscopy, the physicochemical properties of modified cement were detected and analyzed. It was found that after the modification, the main constituents of raw cement, tricalcium silicate and dicalcium silicate had been depleted, and the new crystal mineral of antarcticite replaced them. The iron precipitates and cement hydration products calcium silicate hydrate gel mainly existed in the form of amorphous on modified cement. The results of BET specific surface determination showed that the modified cement particles had mesoporous distribution. The results of adsorption experiment revealed modified cement exhibited excellent adsorption performance on reactive brilliant blue KNR. The combination mechanism between modified cement and adsorbate was mainly electrostatic interaction. The adsorption process satisfied with the pseudo-second order kinetics model, and the adsorption reaction was a spontaneous endothermic process.

Portland cement with additives in the repair of furcation perforations in dogs.

Science.gov (United States)

Silva Neto, José Dias da; Schnaider, Taylor Brandão; Gragnani, Alfredo; Paiva, Anderson Paulo de; Novo, Neil Ferreira; Ferreira, Lydia Masako

2012-11-01

To evaluate the use of Portland cements with additives as furcation perforation repair materials and assess their biocompatibility. 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. There were no significant differences in the amount of newly formed bone between teeth treated with the different obturation materials (p=0.879). Biomineralization occurred for all obturation materials tested, suggesting that these materials have similar biocompatibility.

Effect of radiopaque Portland cement on mineralization in human dental pulp cells.

Science.gov (United States)

Min, Kyung-San; Lee, Sang-Im; Lee, Yoon; Kim, Eun-Cheol

2009-10-01

The aim of this study was to investigate whether radiopaque Portland cement (RPC) facilitates the mineralization process in human dental pulp cells (HDPCs) compared with pure Portland cement (PC). Under a scanning electron microscope (SEM), cellular morphology was evaluated. Alkaline phosphatase (ALP) activity was analyzed, and nodule formation was assessed by performing Alizarin Red S staining. In addition, the mRNA expressions of mineralization-related proteins were evaluated by performing a real-time polymerase chain reaction. On SEM evaluation, healthy HDPCs were found adhering to the surfaces of PC and RPC. The ALP activity increased in the PC and RPC groups compared with the control group at 1 day. Alizarin Red stain increased in the PC and RPC groups compared with the control group at 2 and 3 weeks. The mRNA expression of dentin sialophosphoprotein increased at 14 days in the PC and RPC groups. These results show that PC and RPC have similar effects in terms of mineralization and suggest that RPC also has the potential to be used as a clinically suitable pulp-capping material.

Resistance to acid attack of portland cement mortars produced with red mud as a pozzolanic additive

International Nuclear Information System (INIS)

Balbino, Thiago Gabriel Ferreira; Fortes, Gustavo Mattos; Lourenco, Rafaela Roberta; Rodrigues, Jose de Anchieta

2011-01-01

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

Effect of water curing duration on strength behaviour of portland composite cement (PCC) mortar

Science.gov (United States)

Caronge, M. A.; Tjaronge, M. W.; Hamada, H.; Irmawaty, R.

2017-11-01

Cement manufacturing of Indonesia has been introduced Portland Composite Cement (PCC) to minimize the rising production cost of cement which contains 80% clinker and 20% mineral admixture. A proper curing is very important when the cement contains mineral admixture materials. This paper reports the results of an experimental study conducted to evaluate the effect of water curing duration on strength behaviour of PCC mortar. Mortar specimens with water to cement ratio of (W/C) 0.5 were casted. Compressive strength, flexural strength and concrete resistance were tested at 7, 28 and 91 days cured water. The results indicated that water curing duration is essential to continue the pozzolanic reaction in mortar which contributes to the development of strength of mortar made with PCC.

Effect of wastewater on properties of Portland pozzolana cement

Science.gov (United States)

Babu, G. Reddy

2017-07-01

This paper presents the effect of wastewaters on properties of Portland pozzolana cement (PPC). Fourteen water treatment plants were found out in the Narasaraopet municipality region in Guntur district, Andhra Pradesh, India. Approximately, from each plant, between 3500 and 4000 L/day of potable water is selling to consumers. All plants are extracting ground water and treating through Reverse Osmosis (RO) process. During water treatment, plants are discharging approximately 1,00,000 L/day as wastewater in side drains in Narasaraopet municipality. Physical and chemical analysis was carried out on fourteen plants wastewater and distilled water as per producer described in APHA. In the present work, based on the concentrations of constituent's in wastewater, four typical plants i.e., Narasaraopeta Engineering College (NECWW), Patan Khasim Charitable Trust (PKTWW), Mahmadh Khasim Charitable Trust (MKTWW) and Amara (ARWW) were considered. The performance of four plants wastewater on physical properties i.e., setting times, compressive strength, and flexural strength of Portland pozzolana Cement (PPC) were performed in laboratories and compared same with reference specimens i.e., made with Distilled Water (DW) as mixing water. No significant change was observed in initial and finial setting time but setting times of selected wastewaters were retarded as compared to that of reference water. Almost, no change was observed in 90 days compressive and flexural strengths in four plants wastewaters specimens compared to that of reference water specimens. XRD technique was employed to find out main hydration compounds formed in the process.

Evolution of porosity in a Portland cement paste studied through positron annihilation lifetime spectroscopy

International Nuclear Information System (INIS)

Consolati, G.; Quasso, F.

2003-01-01

Positron annihilation lifetime spectroscopy experiments were carried out in an ordinary Portland cement paste characterized by a water-to-cement ratio w/c=0.8, in order to monitor the porosity of the paste. It was found that ortho-positronium intensity is a suitable quantity to this purpose, being sensitive to the amount of water contained in the pores. The experimental data show good agreement with the porosity calculated according to the Powers' thin filmsodel

Setting temperature evolution of nitrate radwaste immobilized in ordinary portland cement

International Nuclear Information System (INIS)

Rzyski, B.M.; Suarez, A.A.

1988-01-01

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 dm 3 (one US gallon) capacity placed inside a 0.21 m 3 (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

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.

Immobilization of citric acid solutions in portland cement; Imobilizacao de solucoes de acido citrico em cimento Portland

Energy Technology Data Exchange (ETDEWEB)

Lopes, Valdir M.; Rzyski, Barbara M. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

1997-12-01

Decontamination processes by using citric acid on certain items used in the nuclear area, can result in large volumes of liquid wastes with low activity or effluents, contaminated with uranium and some elements dangerous to the environment. A great number of installations that have decontamination processes adopt the zero discharge philosophy. So, one of the forms to isolate the solutions is by reducing its volume through the evaporation process. The generated must can be neutralized and encapsulated or immobilized in Portland cement. This work propose a chemical technique to destroy the citric acid in the decontamination solutions instead of neutralization and, depending on the installation convenience, a direct cement immobilization of these solutions or of the evaporation mud. The results obtained in this work involve data about the workability, setting time and mechanical resistance, after 28 days of sealed cure, for samples with water-cement ratios of 4, 0.5 and 0.6, by weight. (author). 5 refs., 2 tabs.

Sulfoaluminate-belite cement from low-calcium fly ash and sulfur-rich and other industrial by-products

Energy Technology Data Exchange (ETDEWEB)

Arjunan, P.; Silsbee, M.R.; Roy, D.M.

1999-08-01

The study describes the preparation and characterization of an environmentally friendly cement with performance characteristics similar to those of Portland cement, from a lime kiln bag house dust, a low-calcium fly ash, and a scrubber sludge. Promising preliminary results show the formation of relatively low-temperature phases calcium sulfoaluminate (4CaO{center{underscore}dot}3Al{sub 2}O{sub 3}{center{underscore}dot}SO{sub 3}) and dicalcium silicate (2CaO{center{underscore}dot}SiO{sub 2}) at {approximately} 1,250 C if nodulized raw means used for clinker preparation and at 1,175 C if powdered raw meal is used as compared to the {approximately} 1,500 C sintering temperature required for Portland cement. Phases of the developed cements were predicted using modified Bogue calculations. Isothermal calorimetric measurements indicate the hydration properties of the cements are comparable to ordinary Portland cement. Mechanical properties and microstructural evaluations also were carried out.

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

Elementary characterization of samples of Portland cement, natural gypsum and phosphogypsum mortars from Brazil

Energy Technology Data Exchange (ETDEWEB)

Narloch, Danielle Cristine; Paschuk, Sergei Anatolyevich; Corrêa, Janine Nicolosi; Torres, Catarina Alzira Peddis; Mazer, Wellington; Macioski, Gustavo [Universidade Tecnologica Federal do Parana (UTFPR), PR (Brazil); Lara, Alessandro [Universidade de Sao Paulo (USP), SP (Brazil). Departamento de Fisica; Casali, Juliana Machado, E-mail: janine_nicolosi@hotmail.com, E-mail: alellara@hotmail.com, E-mail: jucasali@gmail.com [Instituto Federal de Santa Catarina (IFSC), Florianópolis, SC (Brazil)

2017-07-01

Portland cement, the basic ingredient of concrete and is manufactured by crushing, milling and proportioning limestone, sand, clay, iron ore and secondary materials such as shells, chalk or marl combined with shale slate or blast furnace slag, fly ash, gypsum, phosphogypsum, and some others. Evaluating the physical and mineralogical characteristics of the cement and its chemical composition is essential to establish the quality of the product. Therefore, the objective of this work was to characterize and quantify the most common chemical elements in the samples of Brazilian Portland cement, natural gypsum, and phosphogypsum mortars by means of X-ray dispersive energy spectroscopy (EDXRF), as well as to evaluate the strength of these mortars. For analysis of the compressive strength, initially prepared samples were submitted to a destructive mechanical test. Subsequently samples were milled and compacted to form thin tablets, which were submitted to the EDXRF analysis. The qualitative and quantitative analyzes showed that for phosphogypsum mortar the largest mass fractions were found of 49.8±2.5% (Si), 24.66±0.96% (S) and 22.10±0.42% (Ca). For gypsum mortar those values were found of 43.41±0.45% (Ca), 33.8 ± 0.8% (S) and 18.9±1.2% (Si), respectively; and for Portland cement mortar, the predominant elements in those samples have the mass fractions of 64.20±0.52% (Ca) and 27.3±1.5% (Si). The results showed that obtained values of mass fraction of the elements Si, S, K, Ca, Ti, Fe are in rather good agreement with quantities indicated for manufacture. Besides, gypsum and phosphogypsum presented almost the same composition and compressive strength. (author)

Elementary characterization of samples of Portland cement, natural gypsum and phosphogypsum mortars from Brazil

International Nuclear Information System (INIS)

Narloch, Danielle Cristine; Paschuk, Sergei Anatolyevich; Corrêa, Janine Nicolosi; Torres, Catarina Alzira Peddis; Mazer, Wellington; Macioski, Gustavo; Lara, Alessandro

2017-01-01

Portland cement, the basic ingredient of concrete and is manufactured by crushing, milling and proportioning limestone, sand, clay, iron ore and secondary materials such as shells, chalk or marl combined with shale slate or blast furnace slag, fly ash, gypsum, phosphogypsum, and some others. Evaluating the physical and mineralogical characteristics of the cement and its chemical composition is essential to establish the quality of the product. Therefore, the objective of this work was to characterize and quantify the most common chemical elements in the samples of Brazilian Portland cement, natural gypsum, and phosphogypsum mortars by means of X-ray dispersive energy spectroscopy (EDXRF), as well as to evaluate the strength of these mortars. For analysis of the compressive strength, initially prepared samples were submitted to a destructive mechanical test. Subsequently samples were milled and compacted to form thin tablets, which were submitted to the EDXRF analysis. The qualitative and quantitative analyzes showed that for phosphogypsum mortar the largest mass fractions were found of 49.8±2.5% (Si), 24.66±0.96% (S) and 22.10±0.42% (Ca). For gypsum mortar those values were found of 43.41±0.45% (Ca), 33.8 ± 0.8% (S) and 18.9±1.2% (Si), respectively; and for Portland cement mortar, the predominant elements in those samples have the mass fractions of 64.20±0.52% (Ca) and 27.3±1.5% (Si). The results showed that obtained values of mass fraction of the elements Si, S, K, Ca, Ti, Fe are in rather good agreement with quantities indicated for manufacture. Besides, gypsum and phosphogypsum presented almost the same composition and compressive strength. (author)

Evaluation of the effect of intrinsic material properties and ambient conditions on the dimensional stability of white mineral trioxide aggregate and Portland cement.

Science.gov (United States)

Camilleri, Josette

2011-02-01

A number of factors affect the dimensional stability of a material. These factors include curing conditions, material solubility, leaching, and time. The aim of this study was to evaluate the restrained dimensional change in the vertical direction as a function of the ambient conditions, fluid uptake, solubility, and leaching of white mineral trioxide aggregate (MTA) and Portland cement stored in Hank's balanced salt solution (HBSS) over a period of 28 days. The dimensional change in the vertical direction over a 28-day period was determined using a linear variable differential transducer (LVDT) on laterally restrained test samples. The fluid uptake and solubility of both MTA and Portland cement was also evaluated. The leaching in water and HBSS was assessed using inductively coupled plasma. MTA was more soluble than Portland cement. Both materials absorbed water and physiological solution, with Portland cement displaying a lower uptake than MTA. Both cements exhibited a net expansion when in contact with a physiological solution and released high levels of calcium. MTA leached bismuth. Both calcium and bismuth ion release was higher in HBSS than in water. Phosphorus ions in HBSS were depleted when in contact with both MTA and Portland cement. The MTA was very susceptible to ambient conditions. The addition of bismuth oxide to MTA reduced the leaching of calcium hydroxide, increased the material solubility, and caused deterioration in material dimensional stability. Further research is necessary to establish the material porosity and its effect on the dimensional stability. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Clinical and computed tomographic evaluation of portland cement pulpotomy in primary molar: A case report

Directory of Open Access Journals (Sweden)

Kamrun Nahar

2016-08-01

Full Text Available The present case describes the clinical & radiographic outcome of a Portland Cement pulpotomy. The 5 years old girl presenting extensive carious exposure in her mandibular left 2nd deciduous molar and was suffering pain in her left lower jaw only on exposure to cold for last 2 days. She was ultimately diagnosed clinic-radio-graphically as a case of irreversible pulpitis. Coronal pulpotomy procedure was carried out in the responsible tooth and Portland cement (PC was applied as a medicament after pulpotomy. At the 3 & 6-months follow-up appointments, treated tooth was asymptomatic clinically and radiographic examinations revealed no sign of periradicular pathosis in the pulpotomized teeth. Additionally, the formation of a dentin bridge immediately below the PC in the treated tooth was confirmed by RVG and CBCT.

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

International Nuclear Information System (INIS)

Marques, M.A.; Antunes, M.L.P.; Montagnoli, R.M.; Mancini, S.D.

2012-01-01

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)

Dose response effect of cement dust on respiratory muscles competence in cement mill workers.

Science.gov (United States)

Meo, Sultan A; Azeem, Muhammad A; Qureshi, Aijaz A; Ghori, G Moinudin; Al-Drees, Abdul Majeed; Feisal Subhan, Mirza Muhammad

2006-12-01

Electromyography (EMG) of respiratory muscles is a reliable method of assessing the ventilatory muscle function, but still its use has not been fully utilized to determine the occupational and environmental hazards on respiratory muscles. Therefore, EMG of intercostal muscles was performed to determine the dose response effect of cement dust on respiratory muscles competence. Matched cross-sectional study of EMG in 50 non-smoking cement mill workers with an age range of 20 - 60 years, who worked without the benefit of cement dust control ventilation or respiratory protective devices. EMG was performed by using surface electrodes and chart recorder. Significant reduction was observed in number of peaks (p competence and stratification of results shows a dose-effect of years of exposure in cement mill.

In Vitro Bioactivity and Setting Times of White Portland Cement Combined with Different Radio Pacifying Agents

Directory of Open Access Journals (Sweden)

Coleman Nichola Jayne

2017-01-01

Full Text Available Commercial formulations based on 80:20 mixtures of Portland cement and bismuth oxide (a radiopacifying agent are used in dentistry as root-filling materials. This study compares the impact of two alternative radiopacifiers, barium sulphate and zirconium oxide, with that of bismuth oxide, on the setting times and bioactivity of white Portland cement. The findings indicate that bismuth oxide prolongs both the initial and final setting times of the cement, and that barium sulphate and zirconium oxide have no effect on this parameter. Hydroxyapatite (HA formed on the surfaces of all test samples within 7 days of exposure to simulated body fluid, indicating that they possess the potential to stimulate new hard tissue formation. Fourier transform infrared spectroscopy, the traditional technique for the identification of HA, was not appropriate for the analysis of these cement systems owing to the overlap of signals from each of the radiopacifiers with the characteristic P-O bending modes of HA in the 570 – 610 cm−1 region. In this respect, the P-O band at 965 cm−1 of HA in the Raman spectrum was found to be a suitable means of detection since it is discrete with respect to all signals arising from the radiopacifying agents and cement phases.

Utilization coke dust as fuel in the cement industry

International Nuclear Information System (INIS)

Nawaz, S.

2006-01-01

Utilization of coke dust available from coal carbonization plants, as a fuel in the cement industry has been undertaken and discussed in this research paper. The parameters studied include physical and chemical evaluation of the coke dust and its economic feasibility/ suitability as fuel for the cement plants. Detailed studies have been carried out on the above referred parameters. In addition a comparative study has been done to access its suitability in comparison to other fuels especially imported coal. It has been found that the coke dust contained about 66% fixed carbon, 29% ash, 4% volatile matter, 1% moisture and 0.48% sulphur. It gross calorific value was found to be 5292 Kcal/kg. The detailed analysis of coke dust ash was also performed to determine as to how its constituents will compare with the cement constituents. Keeping in view the experimental results/ data generated on the coke dust, it has been concluded that it can be quite a good substitute for imported coal. In doing so a substantial financial saving can be achieved which ranges 40-45%. (author)

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

Science.gov (United States)

Borges, Alvaro Henrique; Pedro, Fabio Luiz Miranda; Semanoff-Segundo, Alex; Miranda, Carlos Eduardo Saraiva; Pécora, Jesus Djalma; Cruz Filho, Antônio Miranda

2011-01-01

The aim of the present study was to evaluate the radiopacity of Portland and MTA-based cements using the Digora TM digital radiographic system. 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. 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 (pPortland (119.76±22.34), gray Portland (109.71±4.90) and white structural Portland (99.59±12.88) presented lower radiopacity values (pcements were the only materials presenting radiopacity within the ANSI/ADA specifications.

Incorporation of phosphorus guest ions in the calcium silicate phases of Portland cement from 31P MAS NMR spectroscopy.

Science.gov (United States)

Poulsen, Søren L; Jakobsen, Hans J; Skibsted, Jørgen

2010-06-21

Portland cements may contain small quantities of phosphorus (typically below 0.5 wt % P(2)O(5)), originating from either the raw materials or alternative sources of fuel used to heat the cement kilns. This work reports the first (31)P MAS NMR study of anhydrous and hydrated Portland cements that focuses on the phase and site preferences of the (PO(4))(3-) guest ions in the main clinker phases and hydration products. The observed (31)P chemical shifts (10 to -2 ppm), the (31)P chemical shift anisotropy, and the resemblance of the lineshapes in the (31)P and (29)Si MAS NMR spectra strongly suggest that (PO(4))(3-) units are incorporated in the calcium silicate phases, alite (Ca(3)SiO(5)) and belite (Ca(2)SiO(4)), by substitution for (SiO(4))(4-) tetrahedra. This assignment is further supported by a determination of the spin-lattice relaxation times for (31)P in alite and belite, which exhibit the same ratio as observed for the corresponding (29)Si relaxation times. From simulations of the intensities, observed in inversion-recovery spectra for a white Portland cement, it is deduced that 1.3% and 2.1% of the Si sites in alite and belite, respectively, are replaced by phosphorus. Charge balance may potentially be achieved to some extent by a coupled substitution mechanism where Ca(2+) is replaced by Fe(3+) ions, which may account for the interaction of the (31)P spins with paramagnetic Fe(3+) ions as observed for the ordinary Portland cements. A minor fraction of phosphorus may also be present in the separate phase Ca(3)(PO(4))(2), as indicated by the observation of a narrow resonance at delta((31)P) = 3.0 ppm for two of the studied cements. (31)P{(1)H} CP/MAS NMR spectra following the hydration of a white Portland cement show that the resonances from the hydrous phosphate species fall in the same spectral range as observed for (PO(4))(3-) incorporated in alite. This similarity and the absence of a large (31)P chemical shift ansitropy indicate that the hydrous (PO(4

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...

Modelling of Pb release during Portland cement alteration

Energy Technology Data Exchange (ETDEWEB)

Benard, A. [INERIS Mediterrannee, F-13545 Aix En Provence 04 (France); Rose, J.; Borschneck, D.; Bottero, J.Y. [Univ Paul Cezanne, CNRS, UMR 6635, CEREGE, IFR PMSE 112, F-13545 Aix En Provence, (France); Hazemann, J.L. [CNRS, Cristallog Lab, F-38042 Grenoble 09 (France); Proux, O. [Univ Grenoble 1, CNRS, UMR, LGIT, F-38400 St Martin Dheres (France); Trotignon, L. [CEA Cadarache, DTN, SMTM, Lab Modelisat Transferts Environm, 13 - Saint Paul lez Durance (France); Nonat, A. [Univ Bourgogne, CNRS, UMR 5613, Fac Sci Mirande, Lab Rech Reactivite Solides, F-21078 Dijon (France); Chateau, L. [ADEME, F-49004 Angers (France)

2009-07-01

Complex cementitious matrices undergo weathering with environmental exchange and can release metallic pollutants during alteration. The molecular mechanisms responsible for metal release are difficult to identify, though this is necessary if such processes are to be controlled. The present study determines and models the molecular mechanisms of Pb release during Portland cement leaching. As Pb release is strongly related to its speciation (i.e. atomic environment and the nature of bearing phases), the first objective of the present study was to investigate the evolution of Pb retention sites together with the evolution of the cement mineralogy during leaching. Complementary and efficient investigation tools were used, namely X-ray diffraction, micro-X-ray fluorescence and X-ray absorption fine structures. The second objective was to reproduce our results with a reactive transport code (CHESS/HYTEC) in order to test the proposed speciation model of Pb. Combined results indicate that in both the unaltered core and the altered layer of the leached cement, Pb(II) would be retained through C-S-H 'nano-structure', probably linked to a Q(1) or Q(2P) silicate tetrahedra. Moreover in the altered layer, the presence of Fe atoms in the atomic environment of Pb is highly probable. Unfortunately little is known about Fe phases in cement, which makes the interpretation difficult. Can Fe-substituted hydrogranet (C(3)AH(6)) be responsible for Pb retention? Modelling results were consistent with Pb retention through C-S-H in layers and also in an additional, possibly Fe-containing, Pb-retention phase in the altered layer. (authors)

Characteristics of novel root-end filling material using epoxy resin and Portland cement.

Science.gov (United States)

Lee, Sang-Jin; Chung, Jin; Na, Hee-Sam; Park, Eun-Joo; Jeon, Hyo-Jin; Kim, Hyeon-Cheol

2013-04-01

The aim of this study was to evaluate the physical properties and cytotoxicity of a novel root-end filling material (EPC) which is made from epoxy resin and Portland cement as a mineral trioxide aggregate (MTA) substitute. EPC, developed as a root-end filling material, was compared with MTA and a mixture of AH Plus sealer and MTA (AMTA) with regard to the setting time, radio-opacity, and microleakage. Setting times were evaluated using Vicat apparatus. Digital radiographs were taken to evaluate the aluminium equivalent radio-opacity using an aluminium step wedge. Extracted single-rooted teeth were used for leakage test using methylene blue dye. After canal shaping and obturation, the apical 3-mm root was resected, and a root-end cavity with a depth of 3 mm was prepared. The root-end cavities were filled with MTA, AMTA, and EPC for 15 specimens in each of three groups. After setting in humid conditions for 24 h, the specimens were tested for apical leakage. For evaluation of the biocompatibility of EPC, cell (human gingival fibroblast) viability was compared for MTA and Portland cement by MTT assay, and cell morphological changes were compared for MTA and AH Plus by fluorescence microscopy using DAPI and F-actin staining. The setting time, radio-opacity, and microleakage were compared using one-way ANOVA and Scheffe's post hoc comparison, and the cytotoxicity was compared using the nonparametric Kruskal-Wallis rank sum test. Statistical significance was set at 95%. EPC had a shorter setting time and less microleakage compared with MTA (p Portland cement, was found to be a useful material for root-end filling, with favourable radio-opacity, short setting time, low microleakage, and clinically acceptable low cytotoxicity. The novel root-end filling material would be a potentially useful material for a surgical endodontic procedure with favourable properties.

Preparation and Physical Assessment of Portland Cement Base Composites Containing Nano Particles

OpenAIRE

Amir Mahmoudi

2015-01-01

In this research the effects of adding silica and alumina nanoparticles on flow ability and compressive strength of cementitious composites based on Portland cement were investigated. In the first stage, the rheological behavior of different samples containing nanosilica, nanoalumina and polypropylene, polyvinyl alcohol and polyethylene fibers were evaluated. With increasing of nanoparticles in fresh samples, the slump flow diameter reduced. Fibers reduced the flow abilit...

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

Effect of cement dust pollution on certain physical parameters of maize crop and soils

Energy Technology Data Exchange (ETDEWEB)

Parthasarathy, S; Arunachalam, N; Natarajan, K; Oblisami, G; Rangaswami, G

1975-04-01

A study was undertaken in the fields near a cement factory where the cement dust is the prime pollutant to the field crops and soils. Cement dust deposit varied with the distance from the kiln and fourth and fifth leaves of maize had comparatively more dust than the first three leaves from the top. The cement dust deposited plants showed a suppression in most of the characters like leaf size, number and size of cobs and plant height when compared to plants in non-polluted fields. On comparison with the physical characters of the soils from the control field the soil from cement dust polluted field showed a decrease in water holding capacity and pore space while thermal conductivity and specific heat were more. Artificial mixtures of red and black soils with cement dust showed similar trend as those of the field sample, the black soil being affected more seriously than the red soil.

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

International Nuclear Information System (INIS)

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

1997-01-01

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

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

KAUST Repository

Celik, Kemal; Jackson, Marie D.; Mancio, Mauricio; Meral, Cagla; Emwas, Abdul-Hamid M.; Mehta, P. Kumar; Monteiro, Paulo José Meleragno

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.

The influence of calcium nitrate on setting and hardening rate of Portland cement concrete at different temperatures

Science.gov (United States)

Kičaitė, A.; Pundienė, I.; Skripkiūnas, G.

2017-10-01

Calcium nitrate in mortars and concrete is used as a multifunctional additive: as set accelerator, plasticizer, long term strength enhancer and as antifreeze admixture. Used binding material and the amount of calcium nitrate, affect the characteristics of the concrete mixture and strength of hardened concrete. The setting time of the initial and the final binding at different temperatures of hardening (+ 20 °C and + 5 °C) of the pastes made of different cements (Portland cement CEM I 42.5 R and Portland limestone cement CEM II/A-LL 42.5 R) and various amounts of calcium nitrate from 1 % until 3 % were investigated. The effect of calcium nitrate on technological characteristics of concrete mixture (the consistency of the mixture, the density, and the amount of air in the mixture), on early concrete strength after 2 and 7 days, as well as on standard concrete strength after 28 days at different temperatures (at + 20 °C and + 5 °C) were analysed.

Formulation of portland composite cement using waste glass as a supplementary cementitious material

Science.gov (United States)

Manullang, Ria Julyana; Samadhi, Tjokorde Walmiki; Purbasari, Aprilina

2017-09-01

Utilization of waste glass in cement is an attractive options because of its pozzolanic behaviour and the market of glass-composite cement is potentially available. The objective of this research is to evaluate the formulation of waste glass as supplementary cementitious material (SCM) by an extreme vertices mixture experiment, in which clinker, waste glass and gypsum proportions are chosen as experimental variables. The composite cements were synthesized by mixing all of powder materials in jar mill. The compressive strength of the composite cement mortars after being cured for 28 days ranges between 229 to 268 kg/cm2. Composite cement mortars exhibit lower compressive strength than ordinary Portland cement (OPC) mortars but is still capable of meeting the SNI 15-7064-2004 standards. The highest compressive strength is obtained by shifting the cement blend composition to the direction of increasing clinker and gypsum proportions as well as reducing glass proportion. The lower compressive strength of composite cement is caused by expansion due to ettringite and ASR gel. Based on the experimental result, the composite cement containing 80% clinker, 15% glass and 5% gypsum has the highest compressive strength. As such, the preliminary technical feasibility of reuse of waste glass as SCM has been confirmed.

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.

Effects of fibers on expansive shotcrete mixtures consisting of calcium sulfoaluminate cement, ordinary Portland cement, and calcium sulfate

Directory of Open Access Journals (Sweden)

H. Yu

2018-04-01

Full Text Available The mining industry often uses shotcrete for ground stabilization. However, cracking within shotcrete is commonly observed, which delays production schedules and increases maintenance costs. A possible crack reduction method is using expansive shotcrete mixture consisting of calcium sulfoaluminate cement (CSA, ordinary Portland cement (OPC, and calcium sulfate (CS to reduce shrinkage. Furthermore, fibers can be added to the mixture to restrain expansion and impede cracking. The objective of this paper is to study the effects of nylon fiber, glass fiber, and steel fiber on an expansive shotcrete mixture that can better resist cracking. In this study, parameters such as density, water absorption, volume of permeable voids, unconfined compressive strength (UCS, splitting tensile strength (STS, and volume change of fiber-added expansive mixtures were determined at different time periods (i.e. the strengths on the 28th day, and the volume changes on the 1st, 7th, 14th, 21st, and 28th days. The results show that addition of fibers can improve mixture durability, in the form of decreased water absorption and reduced permeable pore space content. Moreover, the expansion of the CSA-OPC-CS mixture was restrained up to 50% by glass fiber, up to 43% by nylon fiber, and up to 28% by steel fiber. The results show that the STS was improved by 57% with glass fiber addition, 43% with steel fiber addition, and 38% with nylon fiber addition. The UCS was also increased by 31% after steel fiber addition, 26% after nylon fiber addition, and 16% after glass fiber addition. These results suggest that fiber additions to the expansive shotcrete mixtures can improve durability and strengths while controlling expansion. Keywords: Shotcrete, Restrained expansion, Fibers, Calcium sulfoaluminate cement (CSA, Ordinary Portland cement (OPC, Calcium sulfate (CS

Red mud addition in the raw meal for the production of Portland cement clinker.

Science.gov (United States)

Tsakiridis, P E; Agatzini-Leonardou, S; Oustadakis, P

2004-12-10

The aim of the present research work was to investigate the possibility of adding red mud, an alkaline leaching waste, which is obtained from bauxite during the Bayer process for alumina production, in the raw meal for the production of Portland cement clinker. For that reason, two samples of raw meals were prepared: one with ordinary raw materials, as a reference sample ((PC)Ref), and another with 3.5% red mud ((PC)R/M). The effect on the reactivity of the raw mix was evaluated on the basis of the unreacted lime content in samples sintered at 1350, 1400 and 1450 degrees C. Subsequently, the clinkers were produced by sintering the two raw meals at 1450 degrees C. The results of chemical and mineralogical analyses as well as the microscopic examination showed that the use of the red mud did not affect the mineralogical characteristics of the so produced Portland cement clinker. Furthermore, both clinkers were tested by determining the grindability, setting time, compressive strength and expansibility. The hydration products were examined by XRD analysis at 2, 7, 28 and 90 days. The results of the physico-mechanical tests showed that the addition of the red mud did not negatively affect the quality of the produced cement.

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

Science.gov (United States)

Coleman, Nichola J; Li, Qiu

2013-01-01

Zirconium oxide has been identified as a candidate radiopacifying agent for use in Portland cement-based biomaterials. During this study, the impact of 20 wt.% zirconium oxide on the hydration and setting reactions of white Portland cement (WPC) was monitored by powder X-ray diffraction (XRD), (29)Si and (27)Al magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), transmission electron microscopy (TEM) and Vicat apparatus. The presence of 20 wt.% zirconium oxide particles in the size-range of 0.2 to 5 μm was found to reduce the initial and final setting times of WPC from 172 to 147 min and 213 to 191 min, respectively. Zirconium oxide did not formally participate in the chemical reactions of the hydrating cement; however, the surface of the zirconium oxide particles presented heterogeneous nucleation sites for the precipitation and growth of the early C-S-H gel products which accelerated the initial setting reactions. The presence of zirconium oxide was found to have little impact on the development of the calcium (sulpho)aluminate hydrate phases. Copyright © 2012 Elsevier B.V. All rights reserved.

Push-out strength of modified Portland cements and resins.

Science.gov (United States)

Iacono, Francesco; Gandolfi, Maria Giovanna; Huffman, Bradford; Sword, Jeremy; Agee, Kelli; Siboni, Francesco; Tay, Franklin; Prati, Carlo; Pashley, David

2010-02-01

Modified calcium-silicate cements derived from white Portland cement (PC) were formulated to test their push-out strength from radicular dentin after immersion for 1 month. Slabs obtained from 42 single-rooted extracted teeth were prepared with 0.6 mm diameter holes, then enlarged with rotary instruments. After immersion in EDTA and NaOC1, the holes were filled with modified PCs or ProRoot MTA, Vitrebond and Clearfil SE. Different concentrations of phyllosilicate (montmorillonite-MMT) were added to experimental cements. ProRoot MTA was also included as reference material. Vitrebond and Clearfil SE were included as controls. Each group was tested after 1 month of immersion in water or PBS. A thin-slice push-out test on a universal testing machine served to test the push-out strength of materials. Results were statistically analyzed using the least squares means (LSM) method. The modified PCs had push-out strengths of 3-9.5 MPa after 1 month of immersion in water, while ProRoot MTA had 4.8 MPa. The push-out strength of PC fell after incubation in PBS for 1 month, while the push-out strength of ProRoot MTA increased. There were no significant changes in Clearfil SE Bond or Vitrebond after water or PBS storage.

Hydrated Ordinary Portland Cement as a Carbonic Cement: The Mechanisms, Dynamics, and Implications of Self-Sealing and CO₂ Resistance in Wellbore Cements

Energy Technology Data Exchange (ETDEWEB)

Guthrie, George Drake Jr. [Los Alamos National Laboratory; Pawar, Rajesh J. [Los Alamos National Laboratory; Carey, James William [Los Alamos National Laboratory; Karra, Satish [Los Alamos National Laboratory; Harp, Dylan Robert [Los Alamos National Laboratory; Viswanathan, Hari S. [Los Alamos National Laboratory

2017-07-28

This report analyzes the dynamics and mechanisms of the interactions of carbonated brine with hydrated Portland cement. The analysis is based on a recent set of comprehensive reactive-transport simulations, and it relies heavily on the synthesis of the body of work on wellbore integrity that we have conducted for the Carbon Storage Program over the past decade.

The influence of the amount addition and kind of the active silica fume in the mechanical properties of the cement Portland concrete

International Nuclear Information System (INIS)

Silva, I.J. da; Melo, A.B. de; Liborio, J.B.L.; Souza, M.F. de

1998-01-01

This study presents an evaluation of the influence of the amount addition and of active silica type deriving from residues of the production of Iron-Silicon alloys of brasilian industries, on the mechanical properties of the concrete made with basaltic aggregates with D max ≥9,5 mm using Portland cements CP II E 32. The study has for objective to evaluate the efficiency of the active silica on the mechanical resistance of the high performance concrete (CAD), when used in substitution of the Portland cement, even so maintaining the same amount of agglomerant material. They are appraised amount of 5%, 8%, 10%, 12% and 15% of active silica in relation to Portland cement mass. The results suggest that for the appraised silicas there is little efficiency. Other aspects related to the mixtures just with addictive water reducers are commented with the purpose of also providing a high performance concrete. (author)

Biomonitoring spatial and temporal impact of atmospheric dust from a cement industry

International Nuclear Information System (INIS)

Branquinho, Cristina; Gaio-Oliveira, Gisela; Augusto, Sofia; Pinho, Pedro; Maguas, Cristina; Correia, Otilia

2008-01-01

The objective of this work was to evaluate the spatial and temporal impact of dust-pollution in the vicinity of a cement industry, located in an area with dry climate. The spatial impact integrated over time was evaluated from the concentrations of Ca, Fe and Mg in in-situ Xanthoria parietina. The temporal pattern was assessed through one-month transplants of the lichen Ramalina canariensis. Four potential sources of atmospheric dust were evaluated: the limestone-quarry; the unpaved roads, the deposit area and the cement mill. Calcium concentration in lichens was considered the best cement-dust indicator. Different types of dust (clinker and grinded-limestone-dust) resulted in different time-patterns of Ca accumulation, which was also related with the different influence that wet and dry periods have in the lichen accumulation process. The dust pollution was found to be deposited locally and dependent on: the nature of dust particles and the volume and frequency of precipitation. - Biomonitoring Spatial and Temporal dust emissions in dry climates

Biomonitoring spatial and temporal impact of atmospheric dust from a cement industry

Energy Technology Data Exchange (ETDEWEB)

Branquinho, Cristina [Universidade de Lisboa, Faculdade de Ciencias, Centro de Ecologia e Biologia Vegetal, Campo Grande, Edificio C2, Piso 4, 1749-016 Lisbon (Portugal); Universidade Atlantica, Antiga Fabrica da Polvora de Barcarena, 2745-615 Barcarena (Portugal)], E-mail: cmbranquinho@fc.ul.pt; Gaio-Oliveira, Gisela; Augusto, Sofia; Pinho, Pedro; Maguas, Cristina; Correia, Otilia [Universidade de Lisboa, Faculdade de Ciencias, Centro de Ecologia e Biologia Vegetal, Campo Grande, Edificio C2, Piso 4, 1749-016 Lisbon (Portugal)

2008-01-15

The objective of this work was to evaluate the spatial and temporal impact of dust-pollution in the vicinity of a cement industry, located in an area with dry climate. The spatial impact integrated over time was evaluated from the concentrations of Ca, Fe and Mg in in-situ Xanthoria parietina. The temporal pattern was assessed through one-month transplants of the lichen Ramalina canariensis. Four potential sources of atmospheric dust were evaluated: the limestone-quarry; the unpaved roads, the deposit area and the cement mill. Calcium concentration in lichens was considered the best cement-dust indicator. Different types of dust (clinker and grinded-limestone-dust) resulted in different time-patterns of Ca accumulation, which was also related with the different influence that wet and dry periods have in the lichen accumulation process. The dust pollution was found to be deposited locally and dependent on: the nature of dust particles and the volume and frequency of precipitation. - Biomonitoring Spatial and Temporal dust emissions in dry climates.

Industrial Wastes as Alternative Mineral Addition in Portland Cement and as Aggregate in Coating Mortars

OpenAIRE

Oliveira, Kamilla Almeida; Nazário, Bruna Inácio; Oliveira, Antonio Pedro Novaes de; Hotza, Dachamir; Raupp-Pereira, Fabiano

2017-01-01

This paper presents an evaluation study of wastes from pulp and paper as well as construction and demolition industries for application in cement-based materials. The alternative raw materials were used as a source of calcium carbonate (CaCO3) and as pozzolanic material (water-reactive SiO2) in partial replacement of Portland cement. In addition to the hydraulic binder, coating mortars were composed by combining the pulp and paper fluidized bed sand residue with construction and demolition wa...

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

International Nuclear Information System (INIS)

Gobbo, Luciano de Andrade; Montanheiro, Tarcisio Jose; Montanheiro, Filipe; Sant'Agostino, Lilia Mascarenhas

2013-01-01

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)

Biocompatibility and setting time of CPM-MTA and white Portland cement clinker with or without calcium sulfate.

Science.gov (United States)

Bramante, Clovis Monteiro; Kato, Marcia Magro; Assis, Gerson Francisco de; Duarte, Marco Antonio Hungaro; Bernardineli, Norberti; Moraes, Ivaldo Gomes de; Garcia, Roberto Brandão; Ordinola-Zapata, Ronald; Bramante, Alexandre Silva

2013-01-01

To evaluate the biocompatibility and the setting time of Portland cement clinker with or without 2% or 5% calcium sulfate and MTA-CPM. Twenty-four mice (Rattus norvegicus) received subcutaneously polyethylene tubes filled with Portland cement clinker with or without 2% or 5% calcium sulfate and MTA. After 15, 30 and 60 days of implantation, the animals were killed and specimens were prepared for microscopic analysis. For evaluation of the setting time, each material was analyzed using Gilmore needles weighing 113.5 g and 456.5 g, according to the ASTM specification Number C266-08 guideline. Data were analyzed by ANOVA and Tukey's test for setting time and Kruskal-Wallis and Dunn test for biocompatibility at 5% significance level. Histologic observation showed no statistically significant difference of biocompatibility (p>0.05) among the materials in the subcutaneous tissues. For the setting time, clinker without calcium sulfate showed the shortest initial and final setting times (6.18 s/21.48 s), followed by clinker with 2% calcium sulfate (9.22 s/25.33 s), clinker with 5% calcium sulfate (10.06 s/42.46 s) and MTA (15.01 s/42.46 s). All the tested materials showed biocompatibility and the calcium sulfate absence shortened the initial and final setting times of the white Portland cement clinker.

Effect of ProRoot MTA, Portland cement, and amalgam on the expression of fibronectin, collagen I, and TGFβ by human periodontal ligament fibroblasts in vitro.

Science.gov (United States)

Fayazi, Sara; Ostad, Seyed Nasser; Razmi, Hasan

2011-01-01

Today many materials have been introduced for root-end filling materials. One of them is mineral trioxide aggregate (MTA) that is mentioned as a gold standard. The purpose of this in vitro study was to evaluate the reaction of human periodontal ligament fibroblasts to the root-end filling materials, such as ProRoot MTA, Portland cement, and amalgam. Eight impacted teeth were extracted in aseptic condition. The tissues around the roots were used to obtain fibroblast cells. After cell proliferation, they were cultured in the chamber slides and the extracts of the materials were added to the wells. Immunocytochemical method for measuring the expression of Fibronectin, collagen I and transforming growth factor beta (TGF®) was performed by Olysia Bioreport Imaging Software. The results were analyzed by SPSS 13.0 and Tukey post hoc test with PPortland cement group showed the most expression of collagen significantly and after 1 week, Portland cement and MTA groups had the most expression of collagen but there was no significant difference between these 2 groups. After 1 week, the Portland cement group demonstrated a higher amount of TGF® and fibronectin. The results suggest that Portland cement can be used as a less expensive root filling material with low toxicity. It has better effects than amalgam on the fibroblasts.

Influence of Ba²⁺ and Sr²⁺ ions on the hydration process of portland cement and blended cements

OpenAIRE

Živanović, B. M.; Petrašinović, Lj.; Milovanović, T.; Karanović, Lj.; Krstanović, I.

1987-01-01

This study concerns the influence of the concentration of Sr2+ and Ba2+ ions in mortar batch waters upon the hydration process of various Portland and additive cements. An increase in the mechanical resistence of said cements is observed, after 28 days, when the concentration of Ba2+ and Sr2+ ions in the mortar batch waters increases. This suggests a possible microstructural explanation of said phenomenon.En el presente trabajo se estudia la influencia de la concentración de los iones Sr2+ y...

Evaluation of the use of red mud as a pozzolanic additive in Portland cement

International Nuclear Information System (INIS)

Fortes, Gustavo Mattos; Balbino, Thiago Gabriel Ferreira; Lourenco, Rafaela Roberta; Rodrigues, Jose de Anchieta

2011-01-01

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

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

Directory of Open Access Journals (Sweden)

Bikić, F.

2013-01-01

Full Text Available The influence of portland cement class on the corrosion rate of steel reinforcement in cement mortar caused by penetrating chloride or sulfate from the environment in already hardened cement mortar is investigated in this paper. Three classes of portland cement have been used for the tests, PC 35, PC 45 and PC 55. Cylindrical samples of cement mortar with steel reinfor- cement in the middle were treated 6 months at room temperature in the following solutions: w(SO42- = 2.1 % and w(Cl- = 5 %. Two techniques have been used for testing corrosion rate of steel reinforcement in cement mortar: Tafel extrapolation technique and potentiodynamic polarization technique. Investigations were conducted by potentiostat/galvanostat Princeton Applied Research 263A-2 with the software PowerCORR®. The results of both techniques indi-cate the most active corrosion of steel reinforcement in the samples prepared from cement PC 35 in both treated solutions, while the lowest corrosion of the steel reinforcement was observed in cement samples prepared from cement PC 55. This conclusion was drawn by analyzing the results shown in Figs. 1–4. Comparing corrosion current density of samples, working electrodes, Figs. 1 and 2, Table 2, the results show the most stable corrosion of steel reinforcement in samples prepared from cement PC 55, and the most active corrosion in samples prepared from ce- ment PC 35. The most active corrosion in samples prepared from cement PC 35 is evident from the positions of the open circuit potentials whose values are less for samples prepared from cement PC 35 in both the treated solution, Figs. 1 and 2, Table 2. Comparison of the anodic polarization curves of the working electrodes in both the treated solutions, Figs. 3 and 4, also shows that the intensity of corrosion is the largest for the working electrodes prepared from cement PC 35 and the smallest for the working electrodes prepared from cement PC 55. Investigation results should be

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

DEFF Research Database (Denmark)

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

2007-01-01

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

Influence of citric acid as setting retarder in CPV portland cement pastes and mortars

International Nuclear Information System (INIS)

Mendes, B.C.; Lopes, M.M.S.; Alvarenga, R.C.S.S.; Fassoni, D.P.; Pedroti, L.G.; Azevedo, A.R.G. de

2016-01-01

This work aims to study the availability of using and the influence of citric acid in the properties of pastes and mortars made with Portland cement CPV ARI both in fresh and hardened form. The citric acid dosages were 0, 0.4%, and 0.8% relative to the cement mass. The produced cement pastes were tested to determine normal consistency water and initial and final setting times. Mortars were tested to determine the consistency index, specific gravity, air entrained content in the fresh stage, hardened bulk density, compressive strength at ages 7, 14, and 28 days, and analysis by XRD technique. The results show that citric acid, besides improve the mortar workability, contribute to an increase in mechanical strength in older than 14 days. (author)

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

Science.gov (United States)

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

2017-01-01

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

The origins of American industrial success: Evidence from the US portland cement industry

OpenAIRE

Prentice, David

2008-01-01

The contributions of innovations, factor endowments and institutions to American industrialization are examined through analysing the rise of the American portland cement industry. Minerals abundance contributed in multiple ways to the spectacular rise of the industry from the 1890s. However, the results of a structural econometric analysis of entry suggests geological surveys, institutions highlighted by David and Wright, played a contributing rather than critical rol...

Waste-form development for conversion to portland cement at Los Alamos National Laboratory (LANL) Technical Area 55 (TA-55)

International Nuclear Information System (INIS)

Veazey, G.W.; Schake, A.R.; Shalek, P.D.; Romero, D.A.; Smith, C.A.

1996-10-01

The process used at TA-55 to cement transuranic (TRU) waste has experienced several problems with the gypsum-based cement currently being used. Specifically, the waste form could not reliably pass the Waste Isolation Pilot Plant (WIPP) prohibition for free liquid and the Environmental Protection Agency (EPA)-Toxicity Characteristic Leaching Procedure (TCLP) standard for chromium. This report describes the project to develop a portland cement-based waste form that ensures compliance to these standards, as well as other performance standards consisting of homogeneous mixing, moderate hydration temperature, timely initial set, and structural durability. Testing was conducted using the two most common waste streams requiring cementation as of February 1994, lean residue (LR)- and oxalate filtrate (OX)-based evaporator bottoms (EV). A formulation with a pH of 10.3 to 12.1 and a minimum cement-to-liquid (C/L) ratio of 0.80 kg/l for OX-based EV and 0.94 kg/L for LR-based EV was found to pass the performance standards chosen for this project. The implementation of the portland process should result in a yearly cost savings for raw materials of approximately $27,000 over the gypsum process

the effect of cement dust exposure on haematological and liver

African Journals Online (AJOL)

Daniel Owu

LIVER FUNCTION PARAMETERS OF CEMENT FACTORY WORKERS IN. SOKOTO ... to cement dust. (mean years of exposure = 9.6± 1.5 years) and 46 matched unexposed controls. ... was assessed by measuring serum liver function tests. .... of cement, may increase the risk of autoimmune disease. ... Mosby's Manual of.

Leaf structural traits of tropical woody species resistant to cement dust.

Science.gov (United States)

Siqueira-Silva, Advanio Inácio; Pereira, Eduardo Gusmão; Modolo, Luzia Valentina; Paiva, Elder Antonio Sousa

2016-08-01

Cement industries located nearby limestone outcrops in Brazil have contributed to the coating of cement dust over native plant species. However, little is known about the extent of the response of tropical woody plants to such environmental pollutant particularly during the first stages of plant development and establishment. This work focused on the investigation of possible alterations in leaf structural and ultrastructural traits of 5-month-old Guazuma ulmifolia Lam. (Malvaceae), 6-month-old Myracrodruon urundeuva Allemão (Anacardiaceae), and 9-month-old Trichilia hirta L. (Meliaceae) challenged superficially with cement dust during new leaf development. Leaf surface of plants, the soil or both (leaf plus soil), were treated (or not) for 60 days, under controlled conditions, with cement dust at 2.5 or 5.0 mg cm(-2). After exposure, no significant structural changes were observed in plant leaves. Also, no plant death was recorded by the end of the experiment. There was also some evidence of localized leaf necrosis in G. ulmifolia and T. hirta, leaf curling in M. urundeuva and T. hirta, and bulges formation on epidermal surface of T. hirta, after cement dust contact with plant shoots. All species studied exhibited stomata obliteration while T. hirta, in particular, presented early leaf abscission, changes in cellular relief, and organization and content of midrib cells. No significant ultrastructural alterations were detected under the experimental conditions studied. Indeed, mesophyll cells presented plastids with intact membrane systems. The high plant survival rates, together with mild morphoanatomic traits alterations in leaves, indicate that G. ulmifolia is more resistant to cement dust pollutant, followed by M. urundeuva and T. hirta. Thus, the three plant species are promising for being used to revegetate areas impacted by cement industries activities.

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

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

Science.gov (United States)

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

2017-03-01

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

Rat subcutaneous tissue response to MTA Fillapex® and Portland cement.

Science.gov (United States)

Marques, Nádia Carolina Teixeira; Lourenço Neto, Natalino; Fernandes, Ana Paula; Rodini, Camila de Oliveira; Duarte, Marco Antônio Hungaro; Oliveira, Thais Marchini

2013-01-01

The aim of this study was to evaluate the response of rat subcutaneous tissue to MTA Fillapex® (Angelus), an experimental root canal filling material based on Portland cement and propylene glycol (PCPG), and a zinc oxide, eugenol and iodoform (ZOEI) paste. These materials were placed in polyethylene tubes and implanted into the dorsal connective tissue of Wistar rats for 7 and 15 days. The specimens were stained with hematoxylin and eosin, and evaluated regarding inflammatory reaction parameters by optical microscopy. The intensity of inflammatory response against the sealers was analyzed by two blinded and previously calibrated examiners for all experimental periods (kappa=0.96). The histological evaluation showed that all materials caused a moderate inflammatory reaction at 7 days, which subsided with time. A greater inflammatory reaction was observed at 7 days in the tubes filled with ZOEI paste. Tubes filled with MTA Fillapex presented some giant cells, macrophages and lymphocytes after 7 days. At 15 days, the presence of fibroblasts and collagen fibers was observed indicating normal tissue healing. The tubes filled with PCPG showed similar results to those observed in MTA Fillapex. At 15 days, the inflammatory reaction was almost absent at the tissue, with several collagen fibers indicating normal tissue healing. Data were analyzed by the nonparametric Kruskal-Wallis test (α=0.05). Statistically significant difference (p0.05). MTA Fillapex and Portland cement added with propylene glycol had greater tissue compatibility than the PCPG paste.

Influence of lead on stabilization/solidification by ordinary Portland cement and magnesium phosphate cement.

Science.gov (United States)

Wang, Yan-Shuai; Dai, Jian-Guo; Wang, Lei; Tsang, Daniel C W; Poon, Chi Sun

2018-01-01

Inorganic binder-based stabilization/solidification (S/S) of Pb-contaminated soil is a commonly used remediation approach. This paper investigates the influences of soluble Pb species on the hydration process of two types of inorganic binders: ordinary Portland cement (OPC) and magnesium potassium phosphate cement (MKPC). The environmental leachability, compressive strength, and setting time of the cement products are assessed as the primary performance indicators. The mechanisms of Pb involved in the hydration process are analyzed through X-ray diffraction (XRD), hydration heat evolution, and thermogravimetric analyses. Results show that the presence of Pb imposes adverse impact on the compressive strength (decreased by 30.4%) and the final setting time (prolonged by 334.7%) of OPC, but it exerts much less influence on those of MKPC. The reduced strength and delayed setting are attributed to the retarded hydration reaction rate of OPC during the induction period. These results suggest that the OPC-based S/S of soluble Pb mainly depends on physical encapsulation by calcium-silicate-hydrate (CSH) gels. In contrast, in case of MKPC-based S/S process, chemical stabilization with residual phosphate (pyromorphite and lead phosphate precipitation) and physical fixation of cementitious struvite-K are the major mechanisms. Therefore, MKPC is a more efficient and chemically stable inorganic binder for the Pb S/S process. Copyright © 2017 Elsevier Ltd. All rights reserved.

The regulation of hazardous air pollutants under the Clean Air Act Amendments of 1990: Effects on the Portland cement industry

International Nuclear Information System (INIS)

Mikols, E.H.; Gill, A.S.; Dougherty, A.

1996-01-01

Title III of the 1990 Clean Air Act Amendments (CAAA) addresses the control of hazardous air pollutants (HAPs) from major sources of air pollution in the US. In the CAAA, Congress defined 189 compounds as hazardous air pollutants in need of additional control by the Environmental Protection Agency (EPA). Congress directed EPA to identify the major source categories which emit HAPs and to prepare regulations that would reduce and control future HAP emissions. This paper outlines the activities undertaken by EPA to regulate HAP emissions from Portland cement plants and the program developed by the Portland cement manufacturing industry to cope with Title III

A randomized clinical trial on the use of medical Portland cement, MTA and calcium hydroxide in indirect pulp treatment.

Science.gov (United States)

Petrou, Marina Agathi; Alhamoui, Fadi Alhaddad; Welk, Alexander; Altarabulsi, Mohammed Basel; Alkilzy, Mohammed; H Splieth, Christian

2014-01-01

Studies on indirect pulp treatment (IPT) show varying success rates of 73 to 97 %. The necessity of re-opening the cavity and the question of the optimal capping material is still under debate. The aim of this prospective in vivo study was to compare the clinical and microbiological outcomes of mineral trioxide aggregate (MTA), medical Portland cement, and calcium hydroxide on the dentin-pulp complex of permanent and primary teeth treated with two-step IPT. In 86 regular patients (51 % men; 49 % women; age 17.2 years ±13.8), one deep carious lesion each was treated with incomplete caries removal, randomly selected capping with either calcium hydroxide (n = 31), medical Portland cement (29) or white MTA (26), and re-entry (6.3 months ±1.0). Clinical (color, humidity, and consistency of dentin) and microbiological (Lactobacilli/Mutans Strep. counts) parameters were recorded at the first and second treatment. The IPT had a high success rate of 90.3 % regardless of the material used (p = 0.72). The arrested lesions showed consistently darker, dry, and therefore, sclerotic dentine (p Portland cement. The findings of this study could promote the improvement of the IPT as a one-step treatment of deep carious lesions when the remaining demineralized dentin would be sealed with durable restorations.

Preparation of composites of national rubber latex (NRL) - portland cement mould. Vol. 3

International Nuclear Information System (INIS)

Dessouki, A.M.; Taher, N.H.; El-Nahas, H.H.

1996-01-01

The aim of this study is to prepare some polymeric mould using national rubber latex (NRL) - portland cement composites based on a delayed- action mechanism. Factors affecting the preparation process such as concentration, mixing percentage, additives and their effect on what is regarded as a delayed action coacervant combination was studied. Composites of national latex (NRL) - portland cement would were prepared as two separate parts. The stabilized natural rubber latex (NRL) 100 parts with hydroxy ethyl cellulose (HEC) 2 parts as stabilizer and a delayed - action coacervant (sodium meta silicate as a delaying agent) 5 parts on one hand and the dry blend of cement 65 parts soluble in 65 parts of water as a paste on the other hand were mixed thoroughly on site. (HEC) was added to the rubber latex to prevent the coagulation of the rubber latex with the electrolyte (sodium meta silicate) present in the rubber mixture. Two kinds of stabilization occurred in the rubber part, namely steric stabilization and the stabilization against electrolyte. The effect of delayed - action coacervant (sodium meta silicate) on the initial setting time of rubber - cement mould showed that the molding process did not occur at sodium meta silicate concentration less than 2.66 parts per 100 parts of rubber latex (phr), and the optimum concentration used was 5% parts of rubber latex. It was observed that addition of a delaying agent (Sodium meta silicate) to the rubber part enhanced the delaying mechanism in the time needed for the molding process, while the addition of the delaying agent to the cement part did not have any effect on retardation of the molding process. Chemical coacervants function mainly by reducing the ζ potential which is associated with the electrical double layer surrounding the latex particle. This reduction may brought about in at least three distinct ways which take place in the system studied. 5 figs., 3 tabs

Preparation of composites of national rubber latex (NRL) - portland cement mould. Vol. 3

Energy Technology Data Exchange (ETDEWEB)

Dessouki, A M; Taher, N H; El-Nahas, H H [National Center for Radiation Research and Technology, Atomic Energy Athority, Cairo (Egypt)

1996-03-01

The aim of this study is to prepare some polymeric mould using national rubber latex (NRL) - portland cement composites based on a delayed- action mechanism. Factors affecting the preparation process such as concentration, mixing percentage, additives and their effect on what is regarded as a delayed action coacervant combination was studied. Composites of national latex (NRL) - portland cement would were prepared as two separate parts. The stabilized natural rubber latex (NRL) 100 parts with hydroxy ethyl cellulose (HEC) 2 parts as stabilizer and a delayed - action coacervant (sodium meta silicate as a delaying agent) 5 parts on one hand and the dry blend of cement 65 parts soluble in 65 parts of water as a paste on the other hand were mixed thoroughly on site. (HEC) was added to the rubber latex to prevent the coagulation of the rubber latex with the electrolyte (sodium meta silicate) present in the rubber mixture. Two kinds of stabilization occurred in the rubber part, namely steric stabilization and the stabilization against electrolyte. The effect of delayed - action coacervant (sodium meta silicate) on the initial setting time of rubber - cement mould showed that the molding process did not occur at sodium meta silicate concentration less than 2.66 parts per 100 parts of rubber latex (phr), and the optimum concentration used was 5% parts of rubber latex. It was observed that addition of a delaying agent (Sodium meta silicate) to the rubber part enhanced the delaying mechanism in the time needed for the molding process, while the addition of the delaying agent to the cement part did not have any effect on retardation of the molding process. Chemical coacervants function mainly by reducing the {zeta} potential which is associated with the electrical double layer surrounding the latex particle. This reduction may brought about in at least three distinct ways which take place in the system studied. 5 figs., 3 tabs.

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

National Emission Standards for Hazardous Air Pollutants (NESHAP) for the Portland Cement Manufacturing Industry Subpart LLL Rule Guidance

Science.gov (United States)

This Spring 2016 document is intended for the use of EPA staff, State and Local regulatory agencies and their staff, and industry plant managers for the NESHAP for the Portland Cement Manufacturing Industry.

Compressive Strength and Physical Properties Behavior of Cement Mortars with addition of Cement Klin Dust

OpenAIRE

Auday A Mehatlaf

2017-01-01

Cement Klin Dust (CKD) was the waste of almost cement industry factories, so that in this paper utilization of CKD as filler in cement and/or concrete was the main objective. CKD from the Karbala cement factory had been used and analysis to know the chemical composition of the oxides was done. In this paper cement mortars with different weight percentages of CKD (0,5,10,20,30,40) had been prepared. Physical properties such as density and porosity were done in different age curing (3, 7, 28) d...

Evaluation of the physical properties of an endodontic Portland cement incorporating alternative radiopacifiers used as root-end filling material.

Science.gov (United States)

Camilleri, J

2010-03-01

To investigate the physical and chemical properties of Portland cement (PC) loaded with alternative radiopacifying materials for use as root-end filling materials in a mineral trioxide aggregate (MTA)-like system. Portland cement loaded with barium sulphate, gold and silver/tin alloy was mixed with water, and the physical and chemical properties of the hydrated cements were evaluated. MTA and intermediate restorative material (IRM) were used as controls. The radiopacity was compared to the equivalent thickness of aluminium, and the setting time of the cements was assessed using an indentation technique. The compressive strength and the stress-strain relationship were determined at 28 days. The stress-strain relationship was determined by monitoring the strain generated when the cement was subjected to compressive load. In addition, the pH was determined in water and simulated body fluid for a period of 28 days. The radiopacity of the cements using alternative radiopacifiers was comparable to MTA (P > 0.05). IRM demonstrated a higher radiopacity than all the materials tested (P cements with the exception of IRM exhibited an alkaline pH and had an extended setting time when compared to IRM. MTA had a longer setting time than the PC (P cement (P = 0.159). The addition of a radiopacifier retarded the setting time (P cements had comparable strength to PC (P > 0.05). IRM was the weakest cement tested (P cement loaded with gold radiopacifier had comparable strength to MTA (P = 1). The stress-strain relationship was linear for all the cements with IRM generating more strain on loading. Within the parameters set in this study, bismuth oxide in MTA can be replaced by gold or silver/tin alloy. The physical, mechanical and chemical properties of the cement replaced with alternative radiopacifiers were similar and comparable to ProRoot MTA.

Temperature Characteristics of Porous Portland Cement Concrete during the Hot Summer Session

Directory of Open Access Journals (Sweden)

Liqun Hu

2017-01-01

Full Text Available Pavement heats the near-surface air and affects the thermal comfort of the human body in hot summer. Because of a large amount of connected porosity of porous Portland cement concrete (PPCC, the thermal parameters of PPCC are much different from those of traditional Portland cement concrete (PCC. The temperature change characteristics of PPCC and the effects on surrounding environment are also different. A continuous 48-hour log of temperature of a PCC and five kinds of PPCC with different porosity were recorded in the open air in the hot summer. The air temperatures at different heights above concrete specimens were tested using self-made enclosed boxes to analyze the characteristics of near-surface air temperature. The output heat flux of different concrete specimens was calculated. The results show that the PPCC has higher temperature in the daytime and lower temperature in the nighttime and larger temperature gradient than the PCC. The air temperature above PPCC is lower than that of PCC after solar radiation going to zero at night. The total output heat flux of PPCC is slightly smaller in the daytime and significantly smaller at night than that of PCC. The results of tests and calculations indicate that PPCC contributes to the mitigation of heating effect of pavement on the near-surface air.

Study of radon diffusion from RHA-modified ordinary Portland cement using SSNTD technique

International Nuclear Information System (INIS)

Narula, A.K.; Goyal, S.K.; Chauhan, R.P.; Chakarvarti, S.K.

2013-01-01

The diffusion coefficient of radon is a very important factor in estimating the rate of indoor radon inflow. The aim of this work is to develop and assess the potential of radon resistant construction materials in residential buildings. Of late, rice husk ash (RHA) has been used as a component in cement. The X-ray diffraction of RHA indicates that the RHA contains mainly amorphous materials while the X-ray fluorescence analysis shows that the major percentage of it is composed of silica. The amorphous silica present in the RHA is responsible for the pozzolonic activity of the ash. The results of the present study indicate that the RHA when mixed with cement initially reduces radon diffusion coefficient, followed by enhancement when the percentage of RHA is increased above 30% by weight. - Highlights: ► Radon diffusion coefficient has been measured in Portland cement with different percentage of rice husk ash (RHA). ► The mixing of RHA to cement changes the radon diffusion coefficient. ► The mixture of cement and RHA can be used to make building materials more resistant to radon entry through diffusion

Optimization of superplasticizer in portland pozzolana cement mortar and concrete

Science.gov (United States)

Sathyan, Dhanya; Anand, K. B.; Mini, K. M.; Aparna, S.

2018-02-01

Chemical Admixtures are added to concrete at the time of mixing of its constituents to impart workability. The requirement of right workability is the essence of good concrete. It has been found that the use of optimum use of admixtures is very important since low dosage may result in loss of fluidity and over dosage could lead to segregation, bleeding, excessive air entrainment etc in concrete. Hence it is essential to find optimum dosage of superplasticizer for getting good strength and workability. But large number of trial tests are required in the field to find the saturation dosage of superplasticizer in concrete which requires more materials and consume more time. The paper deals with developing a co-relation between the quantity requirements of superplasticiser in mortar to that of cement concrete to get good workability. In this work for preparing mortar and concrete 4 brands of locally available Portland pozzolana cement (PPC) and superplasticizer (SP) belonging to 4 different families namely Polycarboxylate Ether (PCE), Lignosulphate (LS), Sulfonated Naphthalene Formaldehyde (SNF) and Sulfonated Melamine Formaldehyde (SMF) are used. Two different brands of SP’s are taken from each family. Workability study on the superplasticized mortar with cement to sand ratio 1:1.5 and water cement ratio of 0.4 was performed using marsh cone and flow table test and workability study on the concrete with same cement/sand ratio and water cement ratio was done using slump cone and flow table test. Saturation dosage of superplasticizer in mortar and concrete determined experimentally was compared to study the correlation between two. Compressive strength study on concrete cubes were done on concrete mixes with a superplasticizer dosage corresponding to the saturation dosage and a comparative study were done to analyse the improvement in the compressive strength with addition of superplasticizer from different family.

Diffusion of He in OPC paste and low-heat Portland cement paste containing fly-ash in contact with aqueous phase

International Nuclear Information System (INIS)

Sato, Fuminori; Miwata, Chikanori; Noda, Natsuko; Sato, Seichi; Kozaki, Tamotsu; Higashihara, Tomohiro; Hironaga, Michihiko; Kawanishi, Motoi

2008-01-01

As a part of gas migration studies in concrete package for nuclear waste surrounded by water-saturated rock, the helium diffusion in ordinary Portland cement paste (OPC) was studied using disk form specimen at various water-to-cement (w/c) ratios. The helium diffusion in low-heat Portland cement paste containing fly-ash (LPF) was also studied. Apparent diffusion coefficients of helium in OPC paste were ∼1 x 10 -10 m 2 s -1 at 0.4 w/c ratio, independent of increase of w/c ratio. It is likely that the materials formation such as C-S-H and CH in capillary pores in OPC plays an important role on the helium diffusion rather than porosity increase. Apparent diffusion coefficient of helium in LPF was two orders of magnitude smaller than that in OPC. It is quite possible that the addition of fly-ash contributes to the formation of hydration products which markedly enhance discontinuity of capillary pore. The results of the present study on the two kinds of cement pastes give us valuable information about alternatives to release gas from cement package. (author)

Modeling the degradation of Portland cement pastes by biogenic organic acids

International Nuclear Information System (INIS)

De Windt, Laurent; Devillers, Philippe

2010-01-01

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.

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

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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.

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

Science.gov (United States)

Pasca, Sorin A; Hartley, Ian D; Reid, Matthew E; Thring, Ronald W

2010-12-17

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.

Resistência à compressão do solo-cimento com substituição parcial do cimento Portland por resíduo cerâmico moído Compressive strength of soil-cement with partial replacement of the Portland cement by crushed ceramic waste

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Rivanildo Dallacort

2002-12-01

Full Text Available Neste trabalho, apresenta-se o estudo experimental da resistência à compressão do solo-cimento, com substituição parcial do cimento Portland por resíduo cerâmico moído. Para tanto, foram ensaiados 81 espécimenes cilíndricos desse material à compressão, em que parte do cimento foi substituída por material cerâmico moído. Realizou-se uma programação fatorial, na qual três variáveis foram selecionadas para estudo: o teor de material ligante (cimento + resíduo cerâmico, a umidade do solo e o teor de resíduo cerâmico adicionado. É apresentado um estudo estatístico através de análise de variância da massa específica do material e da resistência a compressão. Tal estudo permitiu concluir-se que substituições de 25 e 57% do teor de cimento por material cerâmico podem produzir blocos de solo-cimento com resistências superiores a 2 MPa, com teor de material ligante de 6 e 8%, respectivamente.In this paper, an experimental study of the compressive strength of soil-cement with partial replacement of the Portland cement by crushed ceramic waste is presented and discussed. For this, eighty-one cylindrical specimens of soil-cement were tested, where part of cement percentage was replaced by crushed ceramic waste. The experiment was conducted in factorial design and three variables were selected and studied: the binding material content (cement + ceramic waste, soil moisture content and the ratio of ceramic waste. A statistical study using variance analysis of the specific mass and compressive strength of the material is presented. This study concluded that replacement ratios of 25 and 57% of the Portland cement by crushed ceramic material can be used to fabricate soil-cement bricks with strength higher than 2 MPa, for a binding material content of 6 and 8% respectively.

The Fogging Method with Variable of Nozle Diameter as the Mitigation Alternative for Spreading the Dust of Cement

Science.gov (United States)

Purwanta, J.; Marnoto, T.; Setyono, P.; Ramelan, A. H.

2018-03-01

The cement plant impacts on the lives of people around the factory site, one of them on the air quality, especially dust. Cement plant has made various efforts to mitigate dust generated, but the reality on the ground is still a lot of dust flying around either of the cement factory chimneys and transportation. The purpose of this study was to find the optimum condition of nozle diameter from the cement dust catcher, for mitigation the dust spread to around the cement plant. This study uses research methods such as collecting secondary data which includes data intensity rainfall, the average long rains, wind speed and direction as well as data quality monitoring dust around PT. Semen Gresik (Persero) Tbk. Tuban plant. To determine the wind direction propensity models, use a soft Windrose file. To determine the impact on the spread of dust into the environment using secondary data monitoring air quality. Results of the study is that the mitigation of dust around the cement plant is influenced by natural factors, namely the tendency of wind direction, rainfall and rainy days, and the rate of dust emission from the chimney. I try for operate the cement dust catcher with variable of nozle diameter. Finally, I find the optimum condition of nozle diameter for cement dust catcher is 1.40 mm, with line equation is y = 149.09.e 1.6237.x and error 5%. In that condition, nozle can make the fog with a good quality and it can catch the cement dust well.

Cement dust exposure and acute lung function: A cross shift study

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Moen Bente E

2010-04-01

Full Text Available Abstract Background Few studies have been carried out on acute effects of cement dust exposure. This study is conducted to investigate the associations between current "total" dust exposure and acute respiratory symptoms and respiratory function among cement factory workers. Methods A combined cross-sectional and cross-shift study was conducted in Dire Dawa cement factory in Ethiopia. 40 exposed production workers from the crusher and packing sections and 20 controls from the guards were included. Personal "total" dust was measured in the workers' breathing zone and peak expiratory flow (PEF was measured for all selected workers before and after the shift. When the day shift ended, the acute respiratory symptoms experienced were scored and recorded on a five-point Likert scale using a modified respiratory symptom score questionnaire. Results The highest geometric mean dust exposure was found in the crusher section (38.6 mg/m3 followed by the packing section (18.5 mg/m3 and the guards (0.4 mg/m3. The highest prevalence of respiratory symptoms for the high exposed workers was stuffy nose (85% followed by shortness of breath (47% and "sneezing" (45%. PEF decreased significantly across the shift in the high exposed group. Multiple linear regression showed a significant negative association between the percentage cross-shift change in PEF and total dust exposure. The number of years of work in high-exposure sections and current smoking were also associated with cross-shift decrease in PEF. Conclusions Total cement dust exposure was related to acute respiratory symptoms and acute ventilatory effects. Implementing measures to control dust and providing adequate personal respiratory protective equipment for the production workers are highly recommended.

Properties of SiMn slag as apozzolanic material in portland cement manufacture

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Frías, M.

2005-12-01

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

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

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

DEFF Research Database (Denmark)

Lindgreen, Holger; Geiker, Mette; Krøyer, Hanne

2008-01-01

Pozzolanic submicron-sized silica fume and the non-pozzolanic micron- and nano-sized layer silicates (clay minerals) kaolinite, smectite and palygorskite have been used as additives in Portland cement pastes and mortars. These layer silicates have different particle shape (needles and plates......), surface charge, and size (micron and nano). The structure of the resulting cement pastes and mortars has been investigated by atomic force microscopy (AFM), helium porosimetry, nitrogen adsorption (specific surface area and porosity), low-temperature calorimetry (LTC) and thermal analysis. The main result...... is that the cement paste structure and porosity can be engineered by addition of selected layer silicates having specific particle shapes and surface properties (e.g., charge and specific surface area). This seems to be due to the growth of calcium-silicate hydrates (C-S-H) on the clay particle surfaces...

A new aluminium-hydrate species in hydrated Portland cements characterized by 27Al and 29Si MAS NMR spectroscopy

International Nuclear Information System (INIS)

Andersen, Morten Daugaard; Jakobsen, Hans J.; Skibsted, Jorgen

2006-01-01

Recent 27 Al MAS NMR studies of hydrated Portland cements and calcium-silicate-hydrate (C-S-H) phases have shown a resonance from Al in octahedral coordination, which cannot be assigned to the well-known aluminate species in hydrated Portland cements. This resonance, which exhibits the isotropic chemical shift δ iso = 5.0 ppm and the quadrupole product parameter P Q = 1.2 MHz, has been characterized in detail by 27 Al MAS and 27 Al{ 1 H} CP/MAS NMR for different hydrated white Portland cements and C-S-H phases. These experiments demonstrate that the resonance originates from an amorphous or disordered aluminate hydrate which contains Al(OH) 6 3- or O x Al(OH) 6-x (3+x)- units. The formation of the new aluminate hydrate is related to the formation of C-S-H at ambient temperatures, however, it decomposes by thermal treatment at temperatures of 70-90 o C. From the experiments in this work it is proposed that the new aluminate hydrate is either an amorphous/disordered aluminate hydroxide or a calcium aluminate hydrate, produced as a separate phase or as a nanostructured surface precipitate on the C-S-H phase. Finally, the possibilities of Al 3+ for Ca 2+ substitution in the principal layers and interlayers of the C-S-H structure are discussed

Study of air pollution with cement dust and its effect on plants cover in the surrounding area of Tartous cement factory

International Nuclear Information System (INIS)

Meslmani, Y.; Al-Oudat, M.; Al-Kharfan, K.

2000-06-01

Cement dust fall, concentration of total suspended particulate (TSP) and particulate less than 10 micron (PM10), were measured in different sites in the surrounding area of Tartus cement factory. The effects of cement dust emission on the growth of olive trees have been investigated. The results show that the dust fall, TSP and PM10 concentration were higher than The World Health Organization (WHO) standard at the factory site as well as in the surrounding area within 3 to 4 km in the diameter.The study shows that, the cement dust fall decreases the growth of olive trees by 34.5, 33 and 21% regarding the I, II, III sites respectively in comparison with the reference site. The branch length, branch weight, amount of chlorophyll and leaves quantity were decreased significantly. The mean weight of dust fall were 34.5, 26.4 and 10.9 g/m 2 on the leaves area at the site I, II, III respectively while the reference site has a value of 1.9 g/m 2 .(Author)

Study of air pollution with cement dust and its effect on plants cover in the surrounding area of Tartous cement factory

Energy Technology Data Exchange (ETDEWEB)

Meslmani, Y; Al-Oudat, M; Al-Kharfan, K [Atomic Energy Commission, Damascus (Syrian Arab Republic). Dept. of Protection and Safety

2000-06-01

Cement dust fall, concentration of total suspended particulate (TSP) and particulate less than 10 micron (PM10), were measured in different sites in the surrounding area of Tartus cement factory. The effects of cement dust emission on the growth of olive trees have been investigated. The results show that the dust fall, TSP and PM10 concentration were higher than The World Health Organization (WHO) standard at the factory site as well as in the surrounding area within 3 to 4 km in the diameter.The study shows that, the cement dust fall decreases the growth of olive trees by 34.5, 33 and 21% regarding the I, II, III sites respectively in comparison with the reference site. The branch length, branch weight, amount of chlorophyll and leaves quantity were decreased significantly. The mean weight of dust fall were 34.5, 26.4 and 10.9 g/m{sup 2} on the leaves area at the site I, II, III respectively while the reference site has a value of 1.9 g/m{sup 2}.(Author)

Evaluating the freeze-thaw durability of portland cement-stabilized-solidified heavy metal waste using acoustic measurements

International Nuclear Information System (INIS)

El-Korchi, T.; Gress, D.; Baldwin, K.; Bishop, P.

1989-01-01

The use of stress wave propagation to assess freeze-thaw resistance of portland cement solidified/stabilized waste is presented. The stress wave technique is sensitive to the internal structure of the specimens and would detect structural deterioration independent of weight loss or visual observations. The freeze-thaw resistance of a cement-solidified cadmium waste and a control was evaluated. The control and cadmium wastes both showed poor freeze-thaw resistance. However, the addition of cadmium and seawater curing increased the resistance to more cycles of freezing and thawing. This is attributed to microstructural changes

Energy conservation and dust production in wet rotary cement kilns

Energy Technology Data Exchange (ETDEWEB)

Sell, N J; Fischbach, F A

1976-12-01

Energy conservation is currently a major concern of the cement industry. A comparison of data supplied by the U.S. Federal Energy Administration with that gathered in an extensive private study incorporating 29 wet cement plants indicates that a significant reduction of the energy consumed can be accomplished by decreasing the amount of dust generated in the process. Energy saving of 8 percent through dust suppression appears possible by increasing the slurry moisture and by using hammermills rather than impactors as the crushing technique.

Sulfate resistance of nanosilica contained Portland cement mortars

Science.gov (United States)

Batilov, Iani B.

Soils, sea water and ground water high in sulfates are commonly encountered hostile environments that can attack the structure of concrete via chemical and physical mechanisms which can lead to costly repairs or replacement. Sulfate attack is a slow acting deteriorative phenomenon that can result in cracking, spalling, expansion, increased permeability, paste-to-aggregate bond loss, paste softening, strength loss, and ultimately, progressive failure of concrete. In the presented research study, Portland cement (PC) mortars containing 1.5% to 6.0% nanosilica (nS) cement replacement by weight were tested for sulfate resistance through full submersion in sodium sulfate to simulate external sulfate attack. Mortars with comparable levels of cement replacement were also prepared with microsilica (mS). Three cement types were chosen to explore nS' effectiveness to reduce sulfate expansion, when paired with cements of varying tricalcium aluminate (C3A) content and Blaine fineness, and compare it to that of mS. Mortars were also made with combined cement replacement of equal parts nS and mS to identify if they were mutually compatible and beneficial towards sulfate resistance. Besides sulfate attack expansion of mortar bars, the testing program included investigations into transport and microstructure properties via water absorption, sulfate ion permeability, porosimetry, SEM with EDS, laser diffraction, compressive strength, and heat of hydration. Expansion measurements indicated that mS replacement mortars outperformed both powder form nS, and nS/mS combined replacement mixtures. A negative effect of the dry nS powder replacement attributed to agglomeration of its nanoparticles during mixing negated the expected superior filler, paste densification, and pozzolanic activity of the nanomaterial. Agglomerated nS was identified as the root cause behind poor performance of nS in comparison to mS for all cement types, and the control when paired with a low C3A sulfate resistant

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

DEFF Research Database (Denmark)

Fullerton, A; Gammelgaard, Bente; Avnstorp, C

1993-01-01

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

Analysis of metal contents in Portland Type V and MTA-based cements.

Science.gov (United States)

Dorileo, Maura Cristiane Gonçales Orçati; Bandeca, Matheus Coelho; Pedro, Fábio Luis Miranda; Volpato, Luiz Evaristo Ricci; Guedes, Orlando Aguirre; Dalla Villa, Ricardo; Tonetto, Mateus Rodrigues; Borges, Alvaro Henrique

2014-01-01

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 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.

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

Science.gov (United States)

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

Mechanical properties of Self-Consolidating Concrete incorporating Cement Kiln Dust

Directory of Open Access Journals (Sweden)

Mostafa Abd El-Mohsen

2015-04-01

Full Text Available Self-Consolidating Concrete (SCC has been widely used in both practical and laboratory applications. Selection of its components and their ratios depends, mainly, on the target mechanical and physical properties recommended by the project consultant. Partial replacement of cement in SCC with cheap available industrial by-product could produce environmentally durable concrete with similar properties of normal concrete. In the current research, SCC was produced by blending Cement Kiln Dust (CKD with cement in different ratios. Four mixes incorporating cement kiln dust with partial cement replacement of 10%, 20%, 30%, and 40% were produced and compared with a control mix of Normally Vibrated Concrete (NVC. Superplasticizer was used to increase the flow-ability of SCC mixes. The fresh and hardened mechanical properties of all mixes were determined and evaluated. Moreover, time-dependent behavior was investigated for all mixes in terms of drying shrinkage test. The shrinkage strain was measured for all specimens for a period of 120 days. Based on the experimental results, it was found that SCC mixture containing 20% cement replacement of CKD exhibited the highest mechanical strength compared to other SCC mixes and NVC mix as well. It was observed that the volumetric changes of specimens were directly proportional to the increase of the cement replacement ratio.

Biomineralization ability and interaction of mineral trioxide aggregate and white portland cement with dentin in a phosphate-containing fluid.

Science.gov (United States)

Reyes-Carmona, Jessie F; Felippe, Mara S; Felippe, Wilson T

2009-05-01

Mineral trioxide aggregate (MTA) has been shown to be bioactive because of its ability to produce biologically compatible carbonated apatite. This study analyzed the interaction of MTA and white Portland cement with dentin after immersion in phosphate-buffered saline (PBS). Dentin disks with standardized cavities were filled with ProRoot MTA, MTA Branco, MTA BIO, white Portland cement + 20% bismuth oxide (PC1), or PC1 + 10% of calcium chloride (PC2) and immersed in 15 mL of PBS for 2 months. The precipitates were weighed and analyzed by scanning electron microscopy (SEM) and x-ray diffraction. The calcium ion release and pH of the solutions were monitored at 5, 15, 25, and 35 days. The samples were processed for SEM observations. Data were analyzed by using analysis of variance or Kruskall-Wallis tests. Our findings revealed the presence of amorphous calcium phosphate precipitates with different morphologies. The apatite formed by the cement-PBS system was deposited within collagen fibrils, promoting controlled mineral nucleation on dentin, observed as the formation of an interfacial layer with tag-like structures. All the cements tested were bioactive. The cements release some of their components in PBS, triggering the initial precipitation of amorphous calcium phosphates, which act as precursors during the formation of carbonated apatite. This spontaneous precipitation promotes a biomineralization process that leads to the formation of an interfacial layer with tag-like structures at the cement-dentin interface.

PULPOTOMIES WITH PORTLAND CEMENT IN HUMAN PRIMARY MOLARS

Science.gov (United States)

Conti, Taísa Regina; Sakai, Vivien Thiemy; Fornetti, Ana Paula Camolese; Moretti, Ana Beatriz Silveira; Oliveira, Thais Marchini; Lourenço, Natalino; Machado, Maria Aparecida Andrade Moreira; Abdo, Ruy Cesar Camargo

2009-01-01

Two clinical cases in which Portland cement (PC) was applied as a medicament after pulpotomy of mandibular primary molars in children are presented. Pulpotomy using PC was carried out in two mandibular first molars and one mandibular second molar, which were further followed-up. At the 3, 6 and 12-month follow-up appointments, clinical and radiographic examinations of the pulpotomized teeth and their periradicular area revealed that the treatments were successful in maintaining the teeth asymptomatic and preserving pulpal vitality. Additionally, the formation of a dentin bridge immediately below the PC could be observed in the three molars treated. PC may be considered as an effective alternative for primary molar pulpotomies, at least in a short-term period. Randomized clinical trials with human teeth are required in order to determine the suitability of PC before unlimited clinical use can be recommended. PMID:19148409

Moessbauer and calorimetric studies of portland cement hydration in the presence of black gram pulse

International Nuclear Information System (INIS)

Rai, Sarita; Kurian, Sajith; Dwivedi, V. N.; Das, S. S.; Singh, N. B.; Gajbhiye, N. S.

2009-01-01

Effect of different concentrations of naturally occurring admixture in the form of fine powder of black gram pulse (BGP) on the hydration of Portland cement was studied by isothermal calorimetry and 57 Fe Moessbauer spectroscopy. The spectra were recorded for anhydrous cement and the hydration products at room temperature and 77 K. In the presence of BGP, the spectra showed superparamagnetic doublets at room temperature and the sextet at 77 K, due to the presence of fine particles of iron containing component. Moessbauer studies of hydration products confirmed the formation of nanosize hydration products containing Fe 3+ . The isomer shift (δ) and the quadrupole splitting (ΔE Q ) values of C 4 AF in the cement confirmed iron in an octahedral and tetrahedral environment with +3 oxidation state. The high value of quadrupole splitting showed the high asymmetry of the electron environment around the iron atom. The overall mechanism of the hydration of cement in presence of BGP is discussed.

Durabilidad de un suelo contaminado y tratado con cemento portland Durability of a contaminated soil treated with portland cement

Directory of Open Access Journals (Sweden)

José W Jiménez Rojas

2008-01-01

Full Text Available Este trabajo tiene por objetivo la aplicación de la técnica de solidificación/estabilización de suelos contaminados, analizando específicamente el comportamiento físico del suelo a través de ensayos de durabilidad. El suelo fue contaminado en laboratorio con residuo oleoso y la aplicación de la técnica tuvo cómo agente de encapsulamiento el cemento Portland CP V-ARI. Los ensayos de durabilidad, realizados según la NBR 13554 (1996, tuvieron como objetivo estudiar el grado de desagregación y vulnerabilidad del material con diversas combinaciones de dosificaciones de cemento y residuo oleoso, así cómo estudiar la variación volumétrica de los mismos. A partir de los resultados es posible observar que cuanto mayor la cantidad de contaminante, mayor es la pérdida de masa. Sin embargo, cuánto mayor es la cantidad de cemento, menor es la pérdida de masa y menor la variación volumétrica.This work seeks the application of solidification/stabilization techniques to contaminated soils analyzing specifically de physical behavior of the soil through tests of durability. The soil was contaminated in laboratory with acidic oily sludge industrial residues and the application of that technique had an encapsulate agent, the Portland cement CP V-ARI. The tests were carried out according to NBR 13.554 (1996, and they aimed to study the level of degradation and the vulnerability of the material with several combinations of cement and acidic oily sludge as well as study their volumetric variations. Starting from the results, it is possible to observe that the larger the contamination the larger the mass loss; however the larger the amount of cement, the smaller the mass loss and the more stable the volumetric variation.

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)

Impact of cement dust on the mineral and energy concentration of Psidium guayava

Energy Technology Data Exchange (ETDEWEB)

Lai, B.; Ambasht, R.S.

1982-12-01

The impact of cement dust deposition on mineral and energy concentration of leaves of guava Psidium guayava growing in the vicinity of Churk Dement Factory situated at Churk, District-Mirzapur (India) was studied. Concentrations of calcium (Ca), potassium (K), sodium (Na) and phosphorus (P) were increased while energy content (cal g/sup -1/ dry weight) was reduced (12.3%) more in cement-dust-covered leaves than in dust-free leaves of Psidium guayava. Statistically it was found that the difference in the concentration of Ca, K, and P industry and dust-free leaves was highly correlated and significant with the amount of cement dust deposited (gm/sup -2/ leaf surface) on the leaf surface of P. guayava while the difference in the concentration of Na--although positively correlated--is not significant. Maximum values of concentrations of Ca, K, Na, P and energy were 5.20%, 0.48%, 0.025%, 0.15% and 4936.7 cal g/sup -1/ dry weight in dust-covered leaves and 3.50%, 0.30%, 0.018%, 0.12% and 5301.4 cal g/sup -1/ dry weight in dust-free leaves, respectively.

Petrographic Analysis of Portland Cement Concrete Cores from Pease Air National Guard Base, New Hampshire

Science.gov (United States)

2016-11-01

Petrographic Analysis of Portland Cement Concrete Cores from Pease Air National Guard Base, New Hampshire E n g in e e r R e s e a rc h a n d...id, age of the concrete being evaluated and tests performed...4 3 Preface This study was conducted in support of the Air Force Civil Engineer Center (AFCEC) to assess concrete obtained from Pease

Comparison of mineral trioxide aggregate's composition with Portland cements and a new endodontic cement.

Science.gov (United States)

Asgary, Saeed; Eghbal, Mohammad Jafar; Parirokh, Masoud; Ghoddusi, Jamileh; Kheirieh, Sanam; Brink, Frank

2009-02-01

The aim of this study was to compare the compositions of mineral trioxide aggregates (MTAs), Portland cements (PCs), and a new endodontic cement (NEC). Our study also investigated the surface characteristics of MTA and NEC root-end fillings when immersed in normal saline. For part I, we prepared samples of 9 brands of MTAs, PCs, and NEC. The materials were imaged and analyzed by scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA). In part II, 3-mm-deep root-end preparations were filled with MTA or NEC and stored in normal saline for 1 week. Samples were imaged and analyzed by SEM and electron probe microanalysis (EPMA). EDXA investigations revealed differences in the dominant compounds of NEC, PCs, and MTAs. The major components of MTA and PC are the same except for bismuth. The most significant difference was the presence of higher concentrations of Fe (minor element) in gray MTA and PC when compared with white ones. EPMA results revealed remarkably different elements in MTA compared with surrounding dentin, whereas in the NEC group the distribution patterns of calcium, phosphorous, and oxygen were comparable. NEC differs chemically from MTAs and PCs and demonstrates comparable surface composition with adjacent dentin as a root-end filling material.

Physical chemistry of portland-cement hydrate, radioactive-waste hosts: Final report, January 16, 1987--December 31, 1987

International Nuclear Information System (INIS)

Grutzeck, M.W.

1989-01-01

This is a final report summarizing the results of a study of the physical and crystal chemistry of potential hydroxylated radioactive waste hosts compatible with portland cement. Research has focussed on the identification and evaluation of hydrated host phases for four ions: cesium, strontium, iodine and boron. These ions were chosen because they are among the most long lived of the radioactive waste ions as well as the most difficult to immobilize with cement-based materials. Results show that such phases do indeed exist, and that they are excellent host phases for the above ions

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.

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)

Adamu, M.K.; Francis, O.A.

2008-01-01

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 (P 0.05) changes in inorganic phosphorus. Sodium, calcium, chloride and inorganic phosphorus and potassium were significantly (P 0.05) 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)

Impact of cement dust pollution on respiratory systems of Lafarge ...

African Journals Online (AJOL)

In this investigation, the impact of cement dust pollution on respiratory systems of Lafarge cement workers was evaluated. A total of 120 respondents; 60 from the factory workers and 60 (controls) from Ifo, a nearby village 22 km NE of the factory were interviewed in 2014 using a modified respiratory symptom score ...

Feasibility of backfilling mines using cement kiln dust, fly ash, and cement blends

OpenAIRE

Beltagui, Hoda; Sonebi, Mohammed; Maguire, K.; Taylor, Susan

2018-01-01

Cement kiln dust (CKD) is an industrial by-product of the cement manufacturing process, the composition of which can vary widely. Recent years of using alternative fuels have resulted in higher chloride and alkali contents within CKDs; as such, this limits the applications in which CKDs can be utilised. Using a CKD containing a high free lime content of 29.5%, it is shown that this CKD is capable of activating pulverized fuel ash (PFA) due to its high alkalinity, which can be utilised in low ...

Sulfur polymer cement concrete

International Nuclear Information System (INIS)

Weber, H.H.; McBee, W.C.

1990-01-01

Sulfur-based composite materials formulated using sulfur polymer cement (SPC) and mineral aggregates are described and compared with conventional portland cement based materials. Materials characteristics presented include mechanical strength, chemical resistance, impact resistance, moisture permeation, and linear shrinkage during placement and curing. Examples of preparation and placement of sulfur polymer cement concrete (SC) are described using commercial scale equipment. SC applications presented are focused into hostile chemical environments where severe portland cement concrete (PCC) failure has occurred

Determination of the Apical Sealing Abilities of Mineral Trioxide Aggregate, Portland Cement, and Bioaggregate After Irrigation with Different Solutions.

Science.gov (United States)

Bayram, H Melike; Saklar, Feridun; Bayram, Emre; Orucoglu, Hasan; Bozkurt, Alperen

2015-06-01

The purpose of this study was to investigate the sealing ability of root-end filling materials such as mineral trioxide aggregate (MTA), Portland cement, and bioaggregate (BA) after irrigation with different solutions. We examined 130 human maxillar central teeth. After cutting the teeth at the cementoenamel junction, the root canals were expanded using nickel-titanium rotary instruments. Root canals were filled with AH-plus and gutta-percha. Then, the roots were cut apically, and 3 mm deep retrograde cavities were prepared. The roots were divided 12 experimental groups, consisting 10 teeth each; the positive and negative control groups contained five teeth each. The retrograde cavities were rinsed using ethylenediaminetetraacetic acid (EDTA), chlorhexidine (CHX), BioPure(™) mixture of a tetracycline isomer, an acid, and a detergent (MTAD), or distilled water. Next, groups 1, 2, 3, and 4 were sealed with MTA; groups 5, 6, 7, and 8 were sealed with Portland cement; and groups 9, 10, 11, and 12 were sealed with BA. Then, apical microleakage was evaluated by using a computerized fluid filtration method. The results of the leakage test were statistically evaluated by the post-hoc Tukey's test. MTA, Portland cement, and BA root-end filling materials showed the least leakage in the CHX and distilled water groups. The highest leakage was observed in the EDTA and MTAD groups. The sealing ability of BA was as good as that of MTA. EDTA and MTAD increased the apical leakage and CHX and distilled water decreased the leakage of the root-end filling materials examined in this study.

PHYSICAL AND STRENGTH PROPERTIES OF BRICKS PRODUCED FROM PORTLAND CEMENT AND SAW DUST OF DANIELIA OLIVERII WOOD

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David Oriabure EKHUEMELO

2016-12-01

Full Text Available This study investigated the use of sawdust as partial replacement for sand in wood-concrete hollow blocks. Sharp sand, ordinary Portland cement (binder and sawdust were used as raw materials. Sawdust was treated by boiling then sieved after drying using British Standard sieve of 3.35mm to remove sticky wood capable of causing pores. The quantities of sawdust used were 0%, 5%, 10%, 15% and 20%. A mixing proportion of 1:8 cement sand ratio, moulding machine with single 6” (450mm x 225mm x 150mm mould and vibrated with 5.0KW power machine for adequate compaction were used. Wood-concrete block was cured for 28 days. The blocks produced were tested for compressive strength and water absorption. The results showed that mean compressive strength of 100% sand was 2.81N/mm2 followed by 95% sand and 5% sawdust replacement with 1.58N/mm2 ; 90% Sand and 10% sawdust replacement with 0.55N/mm2 ; 85% sand and 15% sawdust replacement with 0.43 N/mm2 and 80% sand 20% sawdust replacement with 0.24N/mm2 . The result further showed that as the percentage of sawdust increased, the compressive strength decreased. At 28 days, the compressive strength of blocks with 5% SD replacement satisfied meets Ghana Building Code for non- load bearing walls. The results also reveals that blocks with 80% sand 20% sawdust replacement level has the highest water absorption (23.72% followed by 85% Sand and 15% sawdust replacement (20.40%; 90% sand and 10% sawdust replacement (18.0%; 95% sand and 5% sawdust replacement (12.12% and 100% sand and 0% sawdust replacement (11.43%. It was concluded that 5% sawdust (8kg replacement and cured 28 days could be used for non-load bearing walls. It was recommended that further research should be carried out to evaluate sawdust replacement level within the range of 1-4% to ascertain results that could be used for various other purposes.

Physical and Strength Properties of Bricks Produced from Portland Cement and Saw Dust of Danielia Oliverii Wood

Directory of Open Access Journals (Sweden)

David Oriabure EKHUEMELO

2016-12-01

Full Text Available This study investigated the use of sawdust as partial replacement for sand in wood-concrete hollow blocks. Sharp sand, ordinary Portland cement (binder and sawdust were used as raw materials. Sawdust was treated by boiling then sieved after drying using British Standard sieve of 3.35mm to remove sticky wood capable of causing pores. The quantities of sawdust used were 0%, 5%, 10%, 15% and 20%. A mixing proportion of 1:8 cement sand ratio, moulding machine with single 6” (450mm x 225mm x 150mm mould and vibrated with 5.0KW power machine for adequate compaction were used. Wood-concrete block was cured for 28 days. The blocks produced were tested for compressive strength and water absorption. The results showed that mean compressive strength of 100% sand was 2.81N/mm2 followed by 95% sand and 5% sawdust replacement with 1.58N/mm2 ; 90% Sand and 10% sawdust replacement with 0.55N/mm2 ; 85% sand and 15% sawdust replacement with 0.43 N/mm2 and 80% sand 20% sawdust replacement with 0.24N/mm2 . The result further showed that as the percentage of sawdust increased, the compressive strength decreased. At 28 days, the compressive strength of blocks with 5% SD replacement satisfied meets Ghana Building Code for non- load bearing walls. The results also reveals that blocks with 80% sand 20% sawdust replacement level has the highest water absorption (23.72% followed by 85% Sand and 15% sawdust replacement (20.40%; 90% sand and 10% sawdust replacement (18.0%; 95% sand and 5% sawdust replacement (12.12% and 100% sand and 0% sawdust replacement (11.43%. It was concluded that 5% sawdust (8kg replacement and cured 28 days could be used for non-load bearing walls. It was recommended that further research should be carried out to evaluate sawdust replacement level within the range of 1-4% to ascertain results that could be used for various other purposes.

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

International Nuclear Information System (INIS)

Milodowski, A.E.; George, I.A.; Bloodworth, A.J.; Robins, N.S.

1985-08-01

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)

Compressive Strength and Physical Properties Behavior of Cement Mortars with addition of Cement Klin Dust

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Auday A Mehatlaf

2017-12-01

Full Text Available Cement Klin Dust (CKD was the waste of almost cement industry factories, so that in this paper utilization of CKD as filler in cement and/or concrete was the main objective. CKD from the Karbala cement factory had been used and analysis to know the chemical composition of the oxides was done. In this paper cement mortars with different weight percentages of CKD (0,5,10,20,30,40 had been prepared. Physical properties such as density and porosity were done in different age curing (3, 7, 28 day. In addition, mechanical properties included the coefficient of thermal conductivity and compressive strength had also observed with different age (3,7, and 28 for all prepared specimens. From the obtained the experimental results and their discussion, it was clear that the addition (20% of CKD had the good results in cement mortars.  

Cytotoxicity of Portland cement with different radiopacifying agents: a cell death study.

Science.gov (United States)

Gomes Cornélio, Ana Lívia; Salles, Loise Pedrosa; Campos da Paz, Mariana; Cirelli, Joni Augusto; Guerreiro-Tanomaru, Juliane Maria; Tanomaru Filho, Mário

2011-02-01

The aim of this study was to investigate the cytotoxicity of white Portland cement (PC) alone or associated with bismuth oxide (PCBi), zirconium oxide (PCZir), and calcium tungstate (PCCa) in 2 cell lineages. Murine periodontal ligament cells (mPDL) and rat osteosarcoma cells (ROS 17/2.8) were exposed for 24 hours to specific concentrations of fresh PC and PC associations with radiopacifiers. Zinc oxide-eugenol cement and hydrogen peroxide treatment were applied as cytotoxic positive controls. Cell viability after incubation with the cements was assessed by mitochondrial dehydrogenase enzymatic assay. Cell morphology was microscopically analyzed by cresyl violet staining, and the mechanism of cell death was determined by acridine orange/ethidium bromide methodology. All data were analyzed statistically by analysis of variance and Tukey post hoc test (P cement elutes. PC alone was not cytotoxic, even at 100 mg/mL. Microscopic images showed that none of the PC formulations caused damage to any cell lines. Statistical analysis of apoptosis/necrosis data demonstrated that PC and PC plus radiopacifying agents promoted significant necrosis cell death only at 100 mg/mL. The mPDL cells were more sensitive than ROS17/2.8. The results showed that PC associated with bismuth oxide, zirconium oxide, or calcium tungstate is not cytotoxic to mPDL or ROS17/2.8. Zirconium oxide and calcium tungstate might be good alternatives as radiopacifying agents. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Physical and microstructural aspects of sulfate attack on ordinary and limestone blended Portland cements

International Nuclear Information System (INIS)

Schmidt, Thomas; Lothenbach, Barbara; Romer, Michael; Neuenschwander, Juerg; Scrivener, Karen

2009-01-01

The consequences of external sulfate attack were investigated by traditional test methods, i.e. length and mass change, as well as by a newly developed, surface sensitive ultrasonic method, using Leaky Rayleigh waves (1 MHz). The macroscopic changes are discussed and compared with thermodynamic calculations and microstructural findings (SEM/EDS). The results show that the main impact of limestone additions on resistance to sulfate degradation are physical - i.e. addition of a few percent in Portland cement reduces the porosity and increases the resistance of Portland cement systems to sulfate; but higher addition of 25% increase porosity and lower resistance to sulfate. The kinetics of degradation were dramatically affected by the solution concentration (4 or 44 g Na 2 SO 4 /l) and the higher concentration also resulted in the formation of gypsum, which did not occur at the low concentration. However the pattern of cracking was similar in both cases and it appears that gypsum precipitates opportunistically in pre-formed cracks so it is not considered as making a significant contribution to the degradation. At 8 deg. C limited formation of thaumasite occurred in the surface region of the samples made from cement with limestone additions. This thaumasite formation led to loss of cohesion of the paste and loss of material from the surface of the samples. However thaumasite formation was always preceded by expansion and cracking of the samples due to ettringite formation and given the very slow kinetics of thaumasite formation it was probably facilitated by the opening up of the structure due to ettringite induced cracking. The expansion of the samples showed a steady stage, followed by a rapidly accelerating stage, with destruction of the samples. The onset of the rapidly accelerating stage occurred when the thickness of the cracked surface layer reached about 1-1.5 mm-10-15% of the total specimen thickness (10 mm).

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

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Xiao-Yong Wang

2017-01-01

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

Numerical simulation of heat and mass transport during hydration of Portland cement mortar in semi-adiabatic and steam curing conditions

OpenAIRE

Hernandez-Bautista, E.; Bentz, D. P.; Sandoval-Torres, S.; de Cano-Barrita, P. F. J.

2016-01-01

A model that describes hydration and heat-mass transport in Portland cement mortar during steam curing was developed. The hydration reactions are described by a maturity function that uses the equivalent age concept, coupled to a heat and mass balance. The thermal conductivity and specific heat of mortar with water-to-cement mass ratio of 0.30 was measured during hydration, using the Transient Plane Source method. The parameters for the maturity equation and the activation energy were obtaine...

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

International Nuclear Information System (INIS)

Giraldelli, M.A.

1990-01-01

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)

THERMOCHEMISTRY OF INTERACTION REACTIONS FOR SODIUM AND ALUMINUM SULPHATES WITH COMPONENTS OF HYDRATING PORTLAND CEMENT

Directory of Open Access Journals (Sweden)

P. I. Yukhnevskiy

2018-01-01

products on the setting and hardening of Portland cement.

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,

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

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

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Mojtaba Shojaei Baghini

2015-01-01

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

Mineral resource of the month: hydraulic cement

Science.gov (United States)

van Oss, Hendrik G.

2012-01-01

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

Clinical and Radiographic Evaluation of the Effectiveness of Formocresol, Mineral Trioxide Aggregate, Portland Cement, and Enamel Matrix Derivative in Primary Teeth Pulpotomies: A Two Year Follow-Up.

Science.gov (United States)

Yildirim, Ceren; Basak, Feridun; Akgun, Ozlem Marti; Polat, Gunseli Guven; Altun, Ceyhan

2016-01-01

The aim of this study was to evaluate and to compare clinical and radiographic outcomes of 4 materials (formocresol, mineral trioxide aggregate (MTA), Portland cement and enamel matrix derivative) using in primary teeth pulpotomies. Sixty-five patients aged 5-9 years (32 female, 33 male) were included in this study. A total of 140 primary first and second molars with deep caries were treated with pulpotomy. All teeth were then restored with stainless steel crowns. The treated teeth were evaluated clinically and radiographically at 3, 6, 12, 18 and 24 months. At 24 months, the clinical success rates of formocresol, MTA, Portland cement, and enamel matrix derivative were 96.9%, 100%, 93.9%, and 93.3%, respectively. The corresponding radiographic success rates were 84.4%, 93.9%, 86.7% and 78.1%, respectively. Although there were no statistically significant differences in clinical and radiographic success rates among the 4 groups, MTA appears to be superior to formocresol, Portland cement, and enamel matrix derivative as a pulpotomy agent in primary teeth.

Cement for Oil Well Cementing Operations in Ghana

African Journals Online (AJOL)

Michael

For Portland cement to qualify as oil well cement, the chemical and physical properties must meet ..... Reservoir Engineering, Stanford University,. Stanford, California, pp. ... Construction”, PhD Thesis, Kwame Nkrumah. University of Science ...

potentials of cement kiln dust in sub-grade improvement

African Journals Online (AJOL)

2013-03-01

Mar 1, 2013 ... alternative uses of waste materials in different geotech- nical application including .... tained in bags and stored in air tight containers. The. CKD was ... Figure 5: Variation of plastic limit with cement kiln dust. Figure 6: Variation ...

Mechanical properties of Self-Consolidating Concrete incorporating Cement Kiln Dust

OpenAIRE

El-Mohsen, Mostafa Abd; Anwar, Ahmed M.; Adam, Ihab A.

2015-01-01

Self-Consolidating Concrete (SCC) has been widely used in both practical and laboratory applications. Selection of its components and their ratios depends, mainly, on the target mechanical and physical properties recommended by the project consultant. Partial replacement of cement in SCC with cheap available industrial by-product could produce environmentally durable concrete with similar properties of normal concrete. In the current research, SCC was produced by blending Cement Kiln Dust (CK...

Scattering Matrix for Typical Urban Anthropogenic Origin Cement Dust and Discrimination of Representative Atmospheric Particulates

Science.gov (United States)

Liu, Jia; Zhang, Yongming; Zhang, Qixing; Wang, Jinjun

2018-03-01

The complete scattering matrix for cement dust was measured as a function of scattering angle from 5° to 160° at a wavelength of 532 nm, as a representative of mineral dust of anthropogenic origin in urban areas. Other related characteristics of cement dust, such as particle size distribution, chemical composition, refractive index, and micromorphology, were also analyzed. For this objective, a newly improved apparatus was built and calibrated using water droplets. Measurements of water droplets were in good agreement with Lorenz-Mie calculations. To facilitate the direct applicability of measurements for cement dust in radiative transfer calculation, the synthetic scattering matrix was computed and defined over the full scattering angle range from 0° to 180°. The scattering matrices for cement dust and typical natural mineral dusts were found to be similar in trends and angular behaviors. Angular distributions of all matrix elements were confined to rather limited domains. To promote the application of light-scattering matrix in atmospheric observation and remote sensing, discrimination methods for various atmospheric particulates (cement dust, soot, smolder smoke, and water droplets) based on the angular distributions of their scattering matrix elements are discussed. The ratio -F12/F11 proved to be the most effective discrimination method when a single matrix element is employed; aerosol identification can be achieved based on -F12/F11 values at 90° and 160°. Meanwhile, the combinations of -F12/F11 with F22/F11 (or (F11 - F22)/(F11 + F22)) or -F12/F11 with F44/F11 at 160° can be used when multiple matrix elements at the same scattering angle are selected.

Alkali-slag cements for the immobilization of radioactive wastes

International Nuclear Information System (INIS)

Shi, C.; Day, R.L.

1996-01-01

Alkali-slag cements consist of glassy slag and an alkaline activator and can show both higher early and later strengths than Type III Portland cement, if a proper alkaline activator is used. An examination of microstructure of hardened alkali-slag cement pastes with the help of XRD and SEM with EDAX shows that the main hydration product is C-S-H (B) with low C/S ratio and no crystalline substances exist such as Ca(OH) 2 , Al (OH) 3 and sulphoaluminates. Mercury intrusion tests indicate that hardened alkali-slag cement pastes have a lower porosity than ordinary Portland cement, and contain mainly gel pores. The fine pore structure of hardened alkali-slag cement pastes will restrict the ingress of deleterious substances and the leaching of harmful species such as radionuclides. The leachability of Cs + from hardened alkali-slag cement pastes is only half of that from hardened Portland cement. From all these aspects, it is concluded that alkali-slag cements are a better solidification matrix than Portland cement for radioactive wastes

Effect of Cement Type on Autogenous Deformation of Cement-Based Materials

DEFF Research Database (Denmark)

Pietro, Lura; Ye, Guang; van Breugel, Klaas

2004-01-01

In this paper, measurements of non-evaporable water content, chemical shrinkage, autogenous deformation, internal relative humidity (RH), pore solution composition, and early-age elastic modulus are presented and discussed. All experiments were performed on Portland cement and blast-furnace slag...... (BFS) cement pastes. Self-desiccation shrinkage of the BFS cement paste was modeled based on the RH measurements, following the capillary-tension approach. The main findings of this study are: 1) self-desiccation shrinkage can be related to self-desiccation both for Portland and for BFS cement pastes......, taking into account the influence of the dissolved salts in the pore solution, 2) the BFS cement paste studied shows pronounced self-desiccation and self-desiccation shrinkage, mainly caused by its very fine pore structure....

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.

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)

Sugiyama, Hisashi; Chino, Shigeo

1999-01-01

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)

New developments of high dust-SCR technology in the cement industry results of pilot tests in Solnhofen and development state of a full scale SCR unit; Nouveaux developpements de la technologie SCR ''High Dust'' dans l'industrie du ciment - resultats de tests pilotes a Solnhoffen et etat de developpement d'une unite pilote a l'echelle

Energy Technology Data Exchange (ETDEWEB)

Samant, G. [Lurgi Energie und Entsorgung GmbH, Frankfurt (Germany); Sauter, G. [Soinhofer Portland Zementwerke AG, Solnhofen (Germany); Haug, N. [Agence Federale de l' Environnement, Berlin (Germany)

2001-07-01

The production of clinker in the cement industry involve the formation of nitrous oxides, and the emission limits are becoming more stringent from year to year. The added up total NOx emissions from the European cement industry amounts at present approx. 450.000 Mg/year. As such it is high time for the decision to develop and implement a technology to reduce NOx-emissions. At present SCR technology which is implemented in the glass industry, waste incineration and power plants seems to be the best economical and ecological solution for cement industry. In the period time from 1997 to the end of 1999 pilot plant test work was carried out by the companies 'Solnhofer Portland Zementwerke AG' and 'mg Engineering Lurgi' in the cement plant in Solnhofen. The results of pilot plan test work show that NOx reduction rates above 90% with NH{sub 3} slip less then 5 vppm can be achieved. The results of the test work with different type of catalysts are discussed. Based on the results of the test work a suitable SCR-process for cement industry is developed. At present a High-Dust-SCR demonstration plant at 'Solnhofer Portland Zementwerke AG' with the help of German Federal Environmental Agency, UBA-Berlin, is under commissioning and going on stream. (authors)

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

International Nuclear Information System (INIS)

Chaipanich, Arnon; Torkittikul, Pincha

2011-01-01

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

Normal and refractory concretes for LMFBR applications. Volume 1. Review of literature on high-temperature behavior of portland cement and refractory concretes. Final report

International Nuclear Information System (INIS)

Bazant, Z.P.; Chern, J.C.; Abrams, M.S.; Gillen, M.P.

1982-06-01

The extensive literature on the properties and behavior at elevated temperature of portland cement concrete and various refractory concretes was reviewed to collect in concise form the physical and chemical properties of castable refractory concretes and of conventional portland cement concretes at elevated temperature. This survey, together with an extensive bibliography of source documents, is presented in Volume 1. A comparison was made of these properties, the relative advantages of the various concretes was evaluated for possible liquid metal fast breeder reactor applications, and a selection was made of several materials of interest for such applications. Volume 2 concludes with a summary of additional knowledge needed to support such uses of these materials together with recommendations on research to provide that knowledge

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)

Patel, Hema; Pandey, Suneel

2012-01-01

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/m 3 ) 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.

Diffusion behavior of anion in hardened low-heat portland cement paste containing fly ash. Dependence of effective diffusion coefficient on pore structure

International Nuclear Information System (INIS)

Chida, Taiji; Yoshida, Takahiro

2012-01-01

In the sub-surface disposal system, the closely packed concrete layer is expected the low diffusivity to retard the migration of radionuclides. Low-heat portland cement containing 30 wt% fly ash (FAC) is a candidate cement material for the construction of sub-surface repository because of its high dense structure and its resistance to cracking. Previously, we reported that FAC has lower diffusivity than Ordinary Portland Cement (OPC) for acetic acid and iodine. However, the mechanism for low diffusivity of FAC was not clear. In this study, the diffusion of multiple trace ions (chlorine, bromine and iodine) in hardened cement pastes was examined by through-diffusion experiments. The effective diffusion coefficients, D e , of the trace ions for hardened OPC cement pastes were on the order of 10 -12 m 2 s -1 for trace ions, and D e for hardened FAC cement pastes were on the order of 10 -13 m 2 s -1 for chlorine, 10 -14 m 2 s -1 for bromine and 10 -15 m 2 s -1 for iodine. Additionally, the pore size distribution and porosity of FAC changed to more closely packed structure for 13 months by the pozzolanic reaction, and the pore size distribution of FAC (mainly 3-10 nm) were an order of magnitude smaller than that of OPC. These results suggest that the low diffusivity of FAC is based on the continuous change in the pore structure and the nano-scale pore size retarding the migration of trace ions. (author)

An Alternative Quality Control Technique for Mineral Chemistry Analysis of Portland Cement-Grade Limestone Using Shortwave Infrared Spectroscopy

Directory of Open Access Journals (Sweden)

Nasrullah Zaini

2016-11-01

Full Text Available Shortwave infrared (SWIR spectroscopy can be applied directly to analyze the mineral chemistry of raw or geologic materials. It provides diagnostic spectral characteristics of the chemical composition of minerals, information that is invaluable for the identification and quality control of such materials. The present study aims to investigate the potential of SWIR spectroscopy as an alternative quality control technique for the mineral chemistry analysis of Portland cement-grade limestone. We used the spectroscopic (wavelength position and depth of absorption feature and geochemical characteristics of limestone samples to estimate the abundance and composition of carbonate and clay minerals on rock surfaces. The depth of the carbonate (CO3 and Al-OH absorption features are linearly correlated with the contents of CaO and Al2O3 in the samples, respectively, as determined by portable X-ray fluorescence (PXRF measurements. Variations in the wavelength position of CO3 and Al-OH absorption features are related to changes in the chemical compositions of the samples. The results showed that the dark gray and light gray limestone samples are better suited for manufacturing Portland cement clinker than the dolomitic limestone samples. This finding is based on the CaO, MgO, Al2O3, and SiO2 concentrations and compositions. The results indicate that SWIR spectroscopy is an appropriate approach for the chemical quality control of cement raw materials.

Influence of citric acid as setting retarder in CPV portland cement pastes and mortars; Influencia do acido citrico como retardador de pega em pastas e argamassas de cimento portland CPV ARI

Energy Technology Data Exchange (ETDEWEB)

Mendes, B.C.; Lopes, M.M.S.; Alvarenga, R.C.S.S.; Fassoni, D.P.; Pedroti, L.G. [Universidade Federal de Vicosa (UFV), MG (Brazil); Azevedo, A.R.G. de, E-mail: afonso.garcez91@gmail.com [Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Campos dos Goytacazes, RJ (Brazil)

2016-07-01

This work aims to study the availability of using and the influence of citric acid in the properties of pastes and mortars made with Portland cement CPV ARI both in fresh and hardened form. The citric acid dosages were 0, 0.4%, and 0.8% relative to the cement mass. The produced cement pastes were tested to determine normal consistency water and initial and final setting times. Mortars were tested to determine the consistency index, specific gravity, air entrained content in the fresh stage, hardened bulk density, compressive strength at ages 7, 14, and 28 days, and analysis by XRD technique. The results show that citric acid, besides improve the mortar workability, contribute to an increase in mechanical strength in older than 14 days. (author)

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.

Effect of Addition of A Marble Dust on Drying Shrinkage Cracks of Cement Mortar Reinforced with Various Fibers

Directory of Open Access Journals (Sweden)

Basim Thabit Al-Khafaji

2017-05-01

Full Text Available This investigation is conducted to study the effect of addition of marble powder (marble dust and different fibers on drying shrinkage cracks and some properties of fibers reinforcment cement mortar. Steel molds having a trapezoidal section, and the end restrained at square shape with( 2.7 meter at length are used to study restrained drying shrinkage of cement mortar. Specimens of ( compressive .flextural. splitting strength were cast. The admixture (marble dust was used to replacie weight of cement with three levels of (4%, 8% and 16% and the fiber hemp and sisal fiber were added for all mixes with proportion by volum of cement . All specimens were cured for (14 days. Average of three results was taken for any test of compressive, tensil and flextural strength. The experimental results showed that the adding of this admixture(marble dust cause adelay in a formation of cracks predicted from a drying shrinkage ,decreases of its width , and hence increases of (compressive, splitting tensil and flextural strength at levels of (4%, and 8%. Thus there is a the positive effect when fiberes added for all mixes of cement mortar with addition of (marble dust. All The admixtures (marble dust and fibers have the obvious visible effect in the delay of the information of shrinkage cracks and the decrease of its width as Compared to the cement mortar mixes when marble dust added a alone.

Effect of wet curing duration on durability parameters of hydraulic cement concretes.

Science.gov (United States)

2010-01-01

Hydraulic cement concrete slabs were cast and stored outdoors in Charlottesville, Virginia, to study the impact of wet curing duration on durability parameters. Concrete mixtures were produced using portland cement, portland cement with slag cement, ...

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)

Thermodynamic description of the solubility of C-S-H gels in hydrated Portland cement. Literature review

International Nuclear Information System (INIS)

Soler, J.M.

2007-11-01

The objective of this study is to compile the available information published in the scientific literature regarding the solubility of C-S-H (calcium silica hydrate) gels, which are the main components of hydrated Portland cement. Modeling the thermodynamic properties of C-S-H, including its incongruent dissolution behavior, is an important requirement to understand the evolution and degradation of hydrated cement and concrete. The thermodynamic modeling of C-S-H started with the use of empirical or semi-empirical models and evolved to the application of solid solution models. Most of the experimental work has been performed at or near 25 deg C and the models are in principle applicable to temperatures near 25 deg C. One of the models provides an explicit dependence on temperature. (orig.)

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.

Cements in Radioactive Waste Disposal

International Nuclear Information System (INIS)

Glasser, F.P.

2013-01-01

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

Cements in Radioactive Waste Disposal

Energy Technology Data Exchange (ETDEWEB)

Glasser, F. P. [University of Aberdeen, Scotland (United Kingdom)

2013-09-15

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

Prediction of chloride ingress and binding in cement paste

DEFF Research Database (Denmark)

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

2007-01-01

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

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.

New Medium for Isolation of Bacteria From Cement Kiln Dust with a Potential to Apply in Bio-Concrete

Science.gov (United States)

Alshalif, A. F.; Irwan, J. M.; Othman, N.; Al-Gheethi, A.

2018-04-01

The present study aimed to introduce a new isolation medium named kiln dust medium (KDM) for recovering of bacteria from cement kiln dust with high pH (>pH 11) without the need for nutrients additives. The cement kiln dust samples were collected from five different areas of Cement Industries of Malaysia Berhad (CIMA). The bacterial isolates were recovered on KDM by direct plating technique. The chemical components for all collected samples were identified using X-ray fluorescence (XRF). The primary identification for the bacterial isolates indicated that these bacteria belongs to Bacillus spp. Based on the morphological characteristics. The growth curve of the bacterial strains was monitored using the optical density (OD) with 650 nm wavelength, which in role confirmed that all isolated bacteria had the ability to grow successfully in the proposed medium. The ability of the bacterial strains to grow at high pH reflects their potential in the bio-concrete applications (aerated and non-aerated concrete). These findings indicated that the cement kiln dust samples from Cement Industries represent the most appropriate source for bacteria used in the bioconcrete.

Study on cementation of simulated radioactive borated liquid wastes

International Nuclear Information System (INIS)

Sun Qina; Li Junfeng; Wang Jianlong

2010-01-01

To compare sulfoaluminate cement with ordinary Portland cement on their cementation of radioactive borated liquid waste and to provide more data for formula optimization, simulated radioactive borated liquid waste were solidified by the two cements. 28 d compressive strength and strength losses after water/freezing/irradiation resistance tests were investigated. Leaching test and X-ray diffraction analysis were also conducted. The results show that it is feasible to solidify borated liquid wastes with sulfoaluminate cement and ordinary Portland cement with formulas used in the study. The 28 d compressive strengths, strength losses after tests and simulated nuclides leaching rates of the solidified waste forms meet the demand of GB 14569.1-93. The sulfoaluminate cement formula show better retention of Cs + than ordinary Portland cement formula. Boron, in form of B (OH) 4 - , incorporate in ettringite as solid solutions. (authors)

The maximum percentage of fly ash to replace part of original Portland cement (OPC) in producing high strength concrete

Science.gov (United States)

Mallisa, Harun; Turuallo, Gidion

2017-11-01

This research investigates the maximum percent of fly ash to replace part of Orginal Portland Cement (OPC) in producing high strength concrete. Many researchers have found that the incorporation of industrial by-products such as fly ash as in producing concrete can improve properties in both fresh and hardened state of concrete. The water-binder ratio was used 0.30. The used sand was medium sand with the maximum size of coarse aggregate was 20 mm. The cement was Type I, which was Bosowa Cement produced by PT Bosowa. The percentages of fly ash to the total of a binder, which were used in this research, were 0, 10, 15, 20, 25 and 30%; while the super platicizer used was typed Naptha 511P. The results showed that the replacement cement up to 25 % of the total weight of binder resulted compressive strength higher than the minimum strength at one day of high-strength concrete.

Dust Full Study In The Surrounding Area Of A Cement Factory And Determination Of The Major Elements Of The Dust Fall Using Neutron Activation Analysis (NAA)

International Nuclear Information System (INIS)

Meslmani, Y.; Al-Oudat, M.

2004-01-01

Dust fall of the Tartous cement factory and the surrounding area at the Syrian coast were measured. The results show that the dust fall concentrations were higher than the World Health Organization (WHO) Standard in the factory site as well as in the surrounding area within 5 to 6 km in the diameter. The value of the dust fall at the Reference sites was abut 4.5 t/km 2 /month and in the surrounding area of the factory values reached between 18 and 120 t/km 2 /month. This means the values exceed the standard around 3 and 13 times. The Neutron Activation Analysis (NAA) of cement dust showed a percentage of 27.5% ± 1.6 of calcium. By the presence of humidity calcium silicate occurs, which immediately dries and becomes a hard salt crust. Therefore in the regions near by the factory cement dust formed this kind of salt coat on the surface of the leaves. (Authors)

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.

Influence of dunite mineral additive on strength of cement

Science.gov (United States)

Vasilyeva, A. A.; Moskvitina, L. V.; Moskvitin, S. G.; Lebedev, M. P.; Fedorova, G. D.

2017-12-01

The work studies the applicability of dunite rocks from Inagli massif (South Yakutia) for the production of mixed (composite) cement. The paper reviews the implementation of dunite for manufacturing materials and products. The chemical and mineral compositions of Inagli massif dunite rocks are presented, which relegate the rocks to magnesia-silicate rocks of low-quality in terms of its application as refractory feedstock due to appreciable serpentinization of dunite. The work presents the results of dunite study in terms of its applicability as an additive to Portland cement. The authors have established that dunite does not feature hydraulicity and can be used as a filling additive to Portland cement in the amount of up to 40%. It was unveiled that the mixed grinding of Portland cement and dunite sand with specific surface area of 5500 cm2/g yields the cement that complies with GOST 31108-2016 for CEM II and CEM V normal-cured cements with strength grades of 32.5 and 42.5. The work demonstrates the benefits of the studies of dunite as a filling additive for producing both Portland cement with mineral component and composite (mixed) cement.

The effect of silica fume on early hydration of white Portland cement via fast field cycling-NMR relaxometry

Science.gov (United States)

Badea, Codruţa.; Bede, Andrea; Ardelean, Ioan

2017-12-01

Fast Field Cycling (FFC) nuclear magnetic resonance (NMR) relaxometry is used to monitor the influence introduced on the hydration process by the addition of silica fume in a cement paste mixture, prepared with white Portland cement. The FFC relaxometry technique was implemented due to its sensitivity to a wider range of molecular motions, which gives more information than other relaxometry techniques performed at a fixed frequency. This unique feature of FFC relaxometry allows better separation of the surface and bulk contributions from the global measured relaxation rate. The relaxation process is dominated by the interaction of water protons with the paramagnetic centers located on the surface of cement grains. In the frame of a two-phase exchange model, this allows the monitoring of the influence of an addition of silica fume on the evolution of surface-to-volume ratio during the early hydration stages.

Arsenic content in Portland cement: a literature review.

Science.gov (United States)

Tenório de Franca, Talita Ribeiro; da Silva, Raphaela Juvenal; Sedycias de Queiroz, Michellini; Aguiar, Carlos Menezes

2010-01-01

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.

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.

Effect of different radiopacifying agents on the physicochemical properties of white Portland cement and white mineral trioxide aggregate.

Science.gov (United States)

Hungaro Duarte, Marco Antonio; Minotti, Paloma Gagliardi; Rodrigues, Clarissa Teles; Zapata, Ronald Ordinola; Bramante, Clovis Monteiro; Tanomaru Filho, Mário; Vivan, Rodrigo Ricci; Gomes de Moraes, Ivaldo; Bombarda de Andrade, Flaviana

2012-03-01

The aim of this study was to evaluate the pH, calcium ion release, setting time, and solubility of white mineral trioxide aggregate (WMTA) and white Portland cement (WPC) combined with the following radiopacifying agents: bismuth oxide (BO), calcium tungstate (CT), and zirconium oxide (ZO). Fifty acrylic teeth with root-end filling material were immersed in ultrapure water for measurement of pH and calcium release (atomic absorption spectrophotometry) at 3, 24, 72, and 168 hours. For evaluation of setting time, each material was analyzed according to the American Society for Testing and Materials guidelines 266/08. The solubility test was performed according to American National Standards Institute/American Dental Association specification no. 57/2000. Solubility, setting time, and pH values were compared by using analysis of variance and Tukey test, and the values of calcium release were compared by the Kruskal-Wallis and Miller tests. The significance level was set at 5%. The pH and calcium release were higher at 3 and 24 hours. WPC was the material with the higher values for both properties. WMTA had the greatest solubility among all materials (P Portland cement. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Impact of chloride on the mineralogy of hydrated Portland cement systems

International Nuclear Information System (INIS)

Balonis, Magdalena; Lothenbach, Barbara; Le Saout, Gwenn; Glasser, Fredrik P.

2010-01-01

Chloride ion is in part bound into ordinary Portland cement paste and modifies its mineralogy. To understand this a literature review of its impacts has been made and new experimental data were obtained. Phase pure preparations of Friedel's salt, Ca 4 Al 2 (Cl) 1.95 (OH) 12.05 .4H 2 O, and Kuzel's salt, Ca 4 Al 2 (Cl)(SO 4 ) 0.5 (OH) 12 .6H 2 O, were synthesized and their solubilities were measured at 5, 25, 55 and 85 o C. After equilibration, solid phases were analysed by X-ray diffraction while the aqueous solutions were analysed by atomic absorption spectroscopy and ion chromatography. The solid solutions and interactions of Friedel's salt with other AFm phases were determined at 25 o C experimentally and by calculations. In hydrated cements, anion sites in AFm are potentially occupied by OH, SO 4 and CO 3 ions whereas Cl may be introduced under service conditions. Chloride readily displaces hydroxide, sulfate and carbonate in the AFm structures. A comprehensive picture of phase relations of AFm phases and their binding capacity for chloride is provided for pH ∼ 12 and 25 o C. The role of chloride in AFt formation and its relevance to corrosion of embedded steel are discussed in terms of calculated aqueous [Cl - ]/[OH - ] molar ratios.

LOW WATER DEMAND CEMENTS - WAY OF EFFICIENT USE OF CLINKER AND MINERAL FILLERS IN CONCRETES

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Khokhryakov Oleg Viktorovich

2017-10-01

Full Text Available Subject: the provisions in the updated edition of the technical specifications for cements are analyzed. A trend to decrease the clinker volume in Portland cement due to the wider use of mineral additives, up to 95%, was observed. Research objectives: substantiation of the most complete and efficient use of Portland cement and mineral additives in the composition of low water demand cements. Materials and methods: portland cement, mineral additives and superplasticizer were used as raw materials for obtaining cements of low water demand. The experimental methods comply with the current standards. Results: comparative properties of low water demand cements and cements with mineral additives are presented. The properties of cement-water suspensions of these binders have been studied, and, on their basis, heavy concretes have been made. The results of the grindability of Portland cement and mineral components with a superplasticizer are given. Conclusions: it is shown that the cement of low water demand, in which the advantages of both Portland cement and mineral additives are more fully and efficiently presented, complies with the tendency to decrease the clinker volume to the greatest degree. It is established that the clinker volume index for heavy concrete prepared on low water demand cement is almost four times lower than that for heavy concrete based on common Portland cement.

Microbial leakage of MTA, Portland cement, Sealapex and zinc oxide-eugenol as root-end filling materials.

Science.gov (United States)

Estrela, Carlos; Estrada-Bernabé, Pedro-Felício; de Almeida-Decurcio, Daniel; Almeida-Silva, Julio; Rodrigues-Araújo-Estrela, Cyntia; Poli-Figueiredo, José-Antonio

2011-05-01

The aim of this study was to compare the microbial leakage of mineral trioxide aggregate (MTA), Portland cement (PC), Sealapex and zinc oxide-eugenol (ZOE) as root-end filling materials. An in vitro microbial leakage test (MLT) with a split chamber was used in this study. A mixture of facultative bacteria and one yeast (S. aureus+E. faecalis+P. aeruginosa+B. subtilis+C. albicans) was placed in the upper chamber and it could only reach the lower chamber containing Brain Heart Infusion broth by way of leakage through the root-end filling. Microbial leakage was observed daily for 60 days. Sixty maxillary anterior human teeth were randomly assigned to different groups--MTA and PC (gray and white), Sealapex+zinc oxide and ZOE, control groups and subgroups to evaluate the influence of EDTA for smear layer removal. These materials were further evaluated by an agar diffusion test (ADT) to verify their antimicrobial efficacy. Data were analyzed statistically by Kruskal-Wallis and Mann-Whitney test. In the MLT, Sealapex+zinc oxide and ZOE did not show evidence of microbial leakage over the 60-day experimental period. The other materials showed leakage from the 15th day. The presence of smear layer influenced microbial leakage. Microbial inhibition zones were not observed in all samples tested by ADT. Sealapex+zinc oxide and ZOE did not show microbial leakage over the experimental period, whereas it was verified within 15 to 45 days in MTA and Portland cement.

Formulating a low-alkalinity cement for radioactive waste repositories

Energy Technology Data Exchange (ETDEWEB)

Coumes, C. Cau Dit; Courtois, S.; Leclercq, S.; Bourbon, X

2004-07-01

A multi-annual research program has been launched in January 2003 by CEA, EDF and ANDRA in order to formulate and characterize low-alkalinity and low-heat cements which would be compatible with an underground waste repository environment. Four types of bindings have been investigated: binary blends of Portland cement and silica fume or metakaolin, as well as ternary blends of Portland cement, fly ash and silica fume or metakaolin. Promising results have been obtained with a mixture comprising 37.5% Portland cement, 32.5% silica fume, and 30% fly ash: pH of water in equilibrium with fully hydrated cement is below 11. Moreover, silica fume compensates for the low reactivity of fly ash, while fly ash allows to reduce water demand, heat release, and dimensional variations of cement pastes and mortars. (authors)

Formulating a low-alkalinity cement for radioactive waste repositories

International Nuclear Information System (INIS)

Coumes, C. Cau Dit; Courtois, S.; Leclercq, S.; Bourbon, X.

2004-01-01

A multi-annual research program has been launched in January 2003 by CEA, EDF and ANDRA in order to formulate and characterize low-alkalinity and low-heat cements which would be compatible with an underground waste repository environment. Four types of bindings have been investigated: binary blends of Portland cement and silica fume or metakaolin, as well as ternary blends of Portland cement, fly ash and silica fume or metakaolin. Promising results have been obtained with a mixture comprising 37.5% Portland cement, 32.5% silica fume, and 30% fly ash: pH of water in equilibrium with fully hydrated cement is below 11. Moreover, silica fume compensates for the low reactivity of fly ash, while fly ash allows to reduce water demand, heat release, and dimensional variations of cement pastes and mortars. (authors)

Effect of Cement Composition in Lampung on Concrete Strength

OpenAIRE

Riyanto, Hery

2014-01-01

The strength and durability of concrete depends on the composition of its constituent materials ie fine aggregate, coarse aggregate, cement, water and other additives. The cement composition is about 10% acting as a binder paste material fine and coarse aggregates. In the Lampung market there are several brands of portland cement used by the community to make concrete construction. Although there is a standard of the government of portland cement composition, yet each brand of cement has diff...

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

Feasibility of backfilling mines using cement kiln dust, fly ash, and cement blends

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Beltagui H.

2018-01-01

Full Text Available Cement kiln dust (CKD is an industrial by-product of the cement manufacturing process, the composition of which can vary widely. Recent years of using alternative fuels have resulted in higher chloride and alkali contents within CKDs; as such, this limits the applications in which CKDs can be utilised. Using a CKD containing a high free lime content of 29.5%, it is shown that this CKD is capable of activating pulverized fuel ash (PFA due to its high alkalinity, which can be utilised in low strength un-reinforced applications. One potential application involves the backfill of mines, reducing the need for continuous maintenance of the mine. This study focuses on the compressive strength achieved by various blends of CKD, PFA, and cement. Samples were hand mixed and compacted in 100 mm x 50 mm diameter cylinders, and unconfined compressive strength measurements taken at 28 and 56 days. The hydration products were assessed through the use of x-ray diffraction and thermogravimetric analysis. Aiming to maximise the use of CKD at a water to binder (w/b ratio of 0.2, it was found that the maximum CKD content possible to achieve the required strength was 90% CKD blended with 10% cement.

Influence of the waste glass in the axial compressive strength of Portland cement concrete

International Nuclear Information System (INIS)

Miranda Junior, E.J.P.; Paiva, A.E.M.

2012-01-01

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)

29 CFR 1910.1000 - Air contaminants.

Science.gov (United States)

2010-07-01

...-06-4 Metal Soluble salts 0.002 Portland cement 65997-15-1 Total dust 15 Respirable fraction 5 Propane..., asbestiform (see 29 CFR 1910.1001) Portland cement 50 Graphite (Natural) 15 Coal Dust: Respirable fraction...: Aerodynamic diameter (unit density sphere) Percent passing selector 2 90 2.5 75 3.5 50 5.0 25 10 0 The...

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

CERN Document Server

American Society for Testing and Materials. Philadelphia

2002-01-01

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

Manufacturing of wollastonite-based glass from cement dust: Physical and mechanical properties

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A.A. Francis

2016-12-01

Full Text Available By-pass cement dust is considered as a source of environmental pollution. Wollastonite-based glass foams are made by adding glass waste and SiC to the cement dust. XRD on samples indicated that the main crystalline phase after heat treatment at 850–1,000°C is wollastonite. Empirical models were developed to derive conclusion on the impact of SiC and temperature on the physical and mechanical properties of the products. The optimum sintering temperature was found to be at 900°C for 60 min, at which crushing strength was about 15 MPa and was the best uniform. Such wollastonite-based glass foam could be very attractive for thermal and acoustic applications.

A review on seashells ash as partial cement replacement

Science.gov (United States)

Mohammad, Wan Ahmad Soffian Bin Wan; Hazurina Othman, Nor; Ibrahim, Mohd Haziman Wan; Rahim, Masazurah A.; Shahidan, Shahiron; Rahman, Raha Abd

2017-11-01

This review paper emphasis on various sea shells ash such as cockle, clam, oyster, mollusc, periwinkle, snail, and green mussel shell ash as partial cement replacement and its objective is to create sustainable environment and reduce problems of global warming. Cement production give huge impact to environment in every stage of its production. These include air pollution in form of dust and, gases, sound and vibration during quarry crushing and milling. One of the solutions to solve this problem is by using modified cement. The modified cement is a cementitious material that meets or exceeds the Portland cement performance by combining and optimizes the recycle and wasted materials. This will indirectly reduce the use of raw materials and then, become a sustain construction materials. Therefore, the replacement of cement in concrete by various sea shell ash may create tremendous saving of energy and also leads to important environmental benefits. This study includes previous investigation done on the properties of chemical and mechanical such as specific gravity, chemical composition, compressive strength, tensile strength and flexural strength of concrete produced using partial replacement of cement by seashells ash. Results show that the optimum percentage of seashells as cement replacement is between 4 - 5%.

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....

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

International Nuclear Information System (INIS)

Poole, T.S.; Wakeley, L.D.; Young, C.L.

1994-03-01

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

Study of the Microstructure Evolution of Low-pH Cements Based on Ordinary Portland Cement (OPC by Mid- and Near-Infrared Spectroscopy, and Their Influence on Corrosion of Steel Reinforcement

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Juan García Olmo

2013-06-01

Full Text Available Low-pH cements are designed to be used in underground repositories for high level waste. When they are based on Ordinary Portland Cements (OPC, high mineral admixture contents must be used which significantly modify their microstructure properties and performance. This paper evaluates the microstructure evolution of low-pH cement pastes based on OPC plus silica fume and/or fly ashes, using Mid-Infrared and Near-Infrared spectroscopy to detect cement pastes mainly composed of high polymerized C-A-S-H gels with low C/S ratios. In addition, the lower pore solution pH of these special cementitious materials have been monitored with embedded metallic sensors. Besides, as the use of reinforced concrete can be required in underground repositories, the influence of low-pH cementitious materials on steel reinforcement corrosion was analysed. Due to their lower pore solution pH and their different pore solution chemical composition a clear influence on steel reinforcement corrosion was detected.

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

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Argiz, C.

2013-03-01

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

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

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.

Characteristics and properties of oil-well cements auditioned with blast furnace slag

International Nuclear Information System (INIS)

Sanchez, 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% 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. 2 9Si and 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.

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

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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.

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

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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

EFFECT OF SEA WATER ON THE STRENGTH OF POROUS CONCRETE CONTAINING PORTLAND COMPOSITE CEMENT AND MICROFILAMENT POLYPROPYLENE FIBER

OpenAIRE

TJARONGE, M.W

2011-01-01

The aim of this research is to study the influence of sea water on the strength of porous concrete containing Portland Composite cement and micro monofilament polypropylene fibre. The specimens of porous concrete were immersed in the sea water up to 28 days. The compressive strength test and flexural strength test were carried out at 3, 7 and 28 days in order to investigate the strength development. The test result indicated that the strength of porous concrete can develop in t...

Prediction of water vapour sorption isotherms and microstructure of hardened Portland cement pastes

International Nuclear Information System (INIS)

Burgh, James M. de; Foster, Stephen J.; Valipour, Hamid R.

2016-01-01

Water vapour sorption isotherms of cementitious materials reflect the multi-scale physical microstructure through its interaction with moisture. Our ability to understand and predict adsorption and desorption behaviour is essential in the application of modern performance-based approaches to durability analysis, along with many other areas of hygro-mechanical and hygro-chemo-mechanical behaviour. In this paper, a new physically based model for predicting water vapour sorption isotherms of arbitrary hardened Portland cement pastes is presented. Established thermodynamic principles, applied to a microstructure model that develops with hydration, provide a rational basis for predictions. Closed-form differentiable equations, along with a rational consideration of hysteresis and scanning phenomena, makes the model suitable for use in numerical moisture simulations. The microstructure model is reconciled with recently published 1 H NMR and mercury intrusion porosimetry results.

Recycling of spent catalyst and waste sludge from industry to substitute raw materials in the preparation of Portland cement clinker

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Kae-Long Lin

2017-09-01

Full Text Available This study investigated the feasibility of using waste limestone sludge, waste stone sludge, iron oxide sludge, and spent catalyst as raw materials in the production of eco-cement. The compressive strength development of the Eco Cement-A (ECO-A paste was similar to that of ordinary Portland cement (OPC pastes. The compressive strength development of the ECO-B paste was higher than that of OPC pastes. In addition, the C2S (Ca2SiO4, C2S and C3S (Ca3SiO5 minerals in the eco-cement paste were continuously utilized to hydrate the Ca(OH2 and calcium silicate hydrates gel (Ca6Si3O12·H2O, C–S–H throughout the curing time. When ECO-C clinker contained 8% spent catalyst, the C3S mineral content decreased and C3A (3 CaO·Al2O3 content increased, thereby causing the structure to weaken and compressive strength to decrease. The results showed that the developed eco-cement with 4% spent catalyst possessed compressive strength properties similar to those of OPC pastes.

High performance concrete with blended cement

International Nuclear Information System (INIS)

Biswas, P.P.; Saraswati, S.; Basu, P.C.

2012-01-01

Principal objectives of the proposed project are two folds. Firstly, to develop the HPC mix suitable to NPP structures with blended cement, and secondly to study its durability necessary for desired long-term performance. Three grades of concrete to b considered in the proposed projects are M35, M50 and M60 with two types of blended cements, i.e. Portland slag cement (PSC) and Portland pozzolana cement (PPC). Three types of mineral admixtures - silica fume, fly ash and ground granulated blast furnace slag will be used. Concrete mixes with OPc and without any mineral admixture will be considered as reference case. Durability study of these mixes will be carried out

Portland cement induces human periodontal ligament cells to differentiate by upregulating miR-146a

Directory of Open Access Journals (Sweden)

Min-Ching Wang

2018-04-01

Full Text Available Background/Purpose: Bioaggregates such as Portland cement (PC can be an economical alternative for mineral trioxide aggregate (MTA with additional benefit of less discoloration. MTA has been known to induce differentiations of several dental cells. MicroRNAs are important regulators of biological processes, including differentiation, physiologic homeostasis, and disease progression. This study is to explore how PC enhances the differentiation of periodontal ligament (PDL cells in microRNAs level. Methods: PDL cells were cultured in a regular PC- or MTA-conditioned medium or an osteoinduction medium (OIM. Alizarin red staining was used to evaluate the extent of mineralization. Transfection of microRNA mimics induced exogenous miR-31 and miR-146a expression. The expression of microRNAs and differentiation markers was assayed using reverse-transcriptase polymerase chain reaction. Results: PC enhanced the mineralization of PDL cells in a dose-dependent manner in the OIM. Exogenous miR-31 and miR-146a expression upregulated alkaline phosphatase (ALP, bone morphogenic protein (BMP, and dentin matrix protein 1 (DMP1 expression. However, miR-31 and miR-146a modulates cementum protein 1 (CEMP1 expression in different ways. PC also enhanced ALP and BMP but attenuated CEMP1 in the OIM. Although the OIM or PC treatment upregulated miR-21, miR-29b, and miR-146a, only miR-146a was able to be induced by PC in combination with OIM. Conclusion: This study demonstrated that PC enhances the differentiation of PDL cells, especially osteogenic through miR-146a upregulation. In order to control the ankylosis after regenerative endodontics with the usage of bioaggregates, further investigations to explore these differentiation mechanisms in the miRNA level may be needed. Keywords: Portland cement, Bioaggregate, miR-146a, Osteogenic differentiation, Periodontal ligament (PDL

Preparation of hydraulic cement

Energy Technology Data Exchange (ETDEWEB)

1921-08-28

A process for the preparation of hydraulic cement by the use of oil-shale residues is characterized in that the oil-shale refuse is mixed with granular basic blast-furnace slag and a small amount of portland cement and ground together.

Assessment the potential of using Carbon nanotubes reinforcements for improving the tensile/flexural strength and fracture toughness of Portland cement paste for damage resistant concrete transportation infrastructures.

Science.gov (United States)

2010-09-01

The focus of this study was on exploring the use of nanotechnology-based nano-filaments, such as carbon : nanotubes (CNTs) and nanofibers (CNFs), as reinforcement in improving the mechanical properties of Portland : cement paste as a construction mat...

Multicomponent modelling of Portland cement hydration reactions

NARCIS (Netherlands)

Ukrainczyk, N.; Koenders, E.A.B.; Van Breugel, K.

2012-01-01

The prospect of cement and concrete technologies depends on more in depth understanding of cement hydration reactions. Hydration reaction models simulate the development of the microstructures that can finally be used to estimate the cement based material properties that influence performance and

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

Blasted copper slag as fine aggregate in Portland cement concrete.

Science.gov (United States)

Dos Anjos, M A G; Sales, A T C; Andrade, N

2017-07-01

The present work focuses on assessing the viability of applying blasted copper slag, produced during abrasive blasting, as fine aggregate for Portland cement concrete manufacturing, resulting in an alternative and safe disposal method. Leaching assays showed no toxicity for this material. Concrete mixtures were produced, with high aggregate replacement ratios, varying from 0% to 100%. Axial compressive strength, diametrical compressive strength, elastic modulus, physical indexes and durability were evaluated. Assays showed a significant improvement in workability, with the increase in substitution of fine aggregate. With 80% of replacement, the concrete presented lower levels of water absorption capacity. Axial compressive strength and diametrical compressive strength decreased, with the increase of residue replacement content. The greatest reductions of compressive strength were found when the replacement was over 40%. For tensile strength by diametrical compression, the greatest reduction occurred for the concrete with 80% of replacement. After the accelerated aging, results of mechanic properties showed a small reduction of the concrete with blasted copper slag performance, when compared with the reference mixture. Results indicated that the blasted copper slag is a technically viable material for application as fine aggregate for concrete mixtures. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

A study of photon interaction in some building materials: High-volume admixture of blast furnace slag into Portland cement

International Nuclear Information System (INIS)

Kurudirek, Murat; Tuerkmen, Ibrahim; Ozdemir, Yueksel

2009-01-01

Total mass attenuation coefficients, mean free paths (MFP), half-value (HVT) and tenth-value (TVT) thicknesses of Portland cement and three mixtures have been calculated in function of the energy from 1 keV to 100 GeV. Both in the low- and high-energy region there were significant variations in those parameters where photoelectric process and pair production partially dominates, respectively. In general, the attenuation parameters were found to vary with chemical composition, density of given material and photon energy.

A study of photon interaction in some building materials: High-volume admixture of blast furnace slag into Portland cement

Energy Technology Data Exchange (ETDEWEB)

Kurudirek, Murat [Faculty of Science, Department of Physics, Ataturk University, 25240 Erzurum (Turkey)], E-mail: mkurudirek@gmail.com; Tuerkmen, Ibrahim [Faculty of Engineering, Department of Civil Engineering, Ataturk University, 25240 Erzurum (Turkey); Ozdemir, Yueksel [Faculty of Science, Department of Physics, Ataturk University, 25240 Erzurum (Turkey)

2009-09-15

Total mass attenuation coefficients, mean free paths (MFP), half-value (HVT) and tenth-value (TVT) thicknesses of Portland cement and three mixtures have been calculated in function of the energy from 1 keV to 100 GeV. Both in the low- and high-energy region there were significant variations in those parameters where photoelectric process and pair production partially dominates, respectively. In general, the attenuation parameters were found to vary with chemical composition, density of given material and photon energy.