WorldWideScience

Sample records for cement based materials

  1. Densified ultra-light cement-based materials

    DEFF Research Database (Denmark)

    Esteves, Luis Pedro

    2015-01-01

    be used as a “clean technology” in the production of cement-based materials for structural applications with a low carbon footprint. This paper describes the principles of this concept coupled with experimental results on the basic properties of this enhanced type of cement-based materials with combined...

  2. Cement-Based Materials for Nuclear Waste Storage

    CERN Document Server

    Cau-di-Coumes, Céline; Frizon, Fabien; Lorente, Sylvie

    2013-01-01

    As the re-emergence of nuclear power as an acceptable energy source on an international basis continues, the need for safe and reliable ways to dispose of radioactive waste becomes ever more critical. The ultimate goal for designing a predisposal waste-management system depends on producing waste containers suitable for storage, transportation and permanent disposal. Cement-Based Materials for Nuclear-Waste Storage provides a roadmap for the use of cementation as an applied technique for the treatment of low- and intermediate-level radioactive wastes.Coverage includes, but is not limited to, a comparison of cementation with other solidification techniques, advantages of calcium-silicate cements over other materials and a discussion of the long-term suitability and safety of waste packages as well as cement barriers. This book also: Discusses the formulation and production of cement waste forms for storing radioactive material Assesses the potential of emerging binders to improve the conditioning of problemati...

  3. Cement-based materials' characterization using ultrasonic attenuation

    Science.gov (United States)

    Punurai, Wonsiri

    The quantitative nondestructive evaluation (NDE) of cement-based materials is a critical area of research that is leading to advances in the health monitoring and condition assessment of the civil infrastructure. Ultrasonic NDE has been implemented with varying levels of success to characterize cement-based materials with complex microstructure and damage. A major issue with the application of ultrasonic techniques to characterize cement-based materials is their inherent inhomogeneity at multiple length scales. Ultrasonic waves propagating in these materials exhibit a high degree of attenuation losses, making quantitative interpretations difficult. Physically, these attenuation losses are a combination of internal friction in a viscoelastic material (ultrasonic absorption), and the scattering losses due to the material heterogeneity. The objective of this research is to use ultrasonic attenuation to characterize the microstructure of heterogeneous cement-based materials. The study considers a real, but simplified cement-based material, cement paste---a common bonding matrix of all cement-based composites. Cement paste consists of Portland cement and water but does not include aggregates. First, this research presents the findings of a theoretical study that uses a set of existing acoustics models to quantify the scattered ultrasonic wavefield from a known distribution of entrained air voids. These attenuation results are then coupled with experimental measurements to develop an inversion procedure that directly predicts the size and volume fraction of entrained air voids in a cement paste specimen. Optical studies verify the accuracy of the proposed inversion scheme. These results demonstrate the effectiveness of using attenuation to measure the average size, volume fraction of entrained air voids and the existence of additional larger entrapped air voids in hardened cement paste. Finally, coherent and diffuse ultrasonic waves are used to develop a direct

  4. Elastoplastic cup model for cement-based materials

    Directory of Open Access Journals (Sweden)

    Yan ZHANG

    2010-03-01

    Full Text Available Based on experimental data obtained from triaxial tests and a hydrostatic test, a cup model was formulated. Two plastic mechanisms, respectively a deviatoric shearing and a pore collapse, are taken into account. This model also considers the influence of confining pressure. In this paper, the calibration of the model is detailed and numerical simulations of the main mechanical behavior of cement paste over a large range of stress are described, showing good agreement with experimental results. The case study shows that this cup model has extensive applicability for cement-based materials and other quasi-brittle and high-porosity materials in a complex stress state.

  5. Using bio-based polymers for curing cement-based materials

    NARCIS (Netherlands)

    Zlopasa, J.; Koenders, E.A.B.; Picken, S.J.

    2014-01-01

    Curing is the process of controlling the rate and extent of moisture loss from the surface of cement based materials. It is the final stage in the production of cement-based materials and it is the essential part for achieving continuous hydration of cement, while avoiding cracking due to drying shr

  6. Multiscale Lattice Boltzmann-Finite Element Modelling of Transport Properties in Cement-based Materials

    NARCIS (Netherlands)

    Zhang, M.

    2013-01-01

    Cement-based materials are the most widely used man-made materials in the world. The durability of cement-based materials has been a major concern due to the premature failure and serviceability issues of many reinforced concrete structures. Durability of cement-based materials is to a large content

  7. 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....

  8. Sorption of radionuclides by cement-based barrier materials

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kefei, E-mail: likefei@tsinghua.edu.cn; Pang, Xiaoyun

    2014-11-15

    This paper investigates the sorption of radionuclide ions, {sup 137}Cs{sup +} and {sup 90}Sr{sup 2+}, by cement-based barrier materials for radioactive waste disposal. A mortar with ternary binder is prepared and powder samples are ground from the hardened material following a predetermined granulometry. After pre-equilibrium with an artificial pore solution, the sorption behaviors of powder samples are investigated through single sorption and blended sorption. The results show that: (1) no systematic difference is observed for single and blended sorptions thus the interaction between {sup 137}Cs{sup +} and {sup 90}Sr{sup 2+} sorptions must be weak; (2) the sorption kinetics is rapid and all characteristic times are less than 1d; (3) the sorption capacity is enhanced by C–A–S–H hydrates and the measured K{sub d} values can be predicted from C–S–H sorption data with Ca/Si ratio equal to Ca/(Si + Al) ratio.

  9. Three-dimensional Microstructure Simulation Model of Cement Based Materials,

    NARCIS (Netherlands)

    Ye, G.; Van Breugel, K.

    2003-01-01

    This paper describes a computer-based numerical model for the simulation of the development of microstructure during cement hydration. Special emphasis is on the algorithm for characterizing the pores. This includes the porosity and the pore size distribution and the topological properties of the po

  10. Properties and interfacial microstructure of cement-based materials with composite micro-grains

    Institute of Scientific and Technical Information of China (English)

    FENG Qi; BA Heng-jing; LIU Jun-zhe

    2005-01-01

    Silica fume, fly ash and nano-fiber mineral materials (NR powder) are employed to incorporate into cement-based materials. According to the grain grading mathematical model of cement-based materials, two packing systems, namely, spherical grading system and nano-fiber reinforced system were designed. Properties and interfacial microstructure of the two systems were studied according to secondary interface theory. It was shown that nano-fiber mineral materials can improve the grain grading of the admixture, increase the density of the system, improve the microstructure of the interface and the hardened paste, and enhance the uniformity of cement-based materials mixed with composite micro-grains and greatly increase their wearable rigidity and flexure strength. In this paper, two kinds of interface models, including spherical grain model and nano-fiber reinforced interface model of the cement-based materials mixed with composite micro-grains, were brought forward.

  11. Elastoplastic cup model for cement-based materials

    OpenAIRE

    Zhang, Yan; Shao, Jian-Fu

    2010-01-01

    Based on experimental data obtained from triaxial tests and a hydrostatic test, a cup model was formulated. Two plastic mechanisms, respectively a deviatoric shearing and a pore collapse, are taken into account. This model also considers the influence of confining pressure. In this paper, the calibration of the model is detailed and numerical simulations of the main mechanical behavior of cement paste over a large range of stress are described, showing good agreement with experimental results...

  12. An ongoing investigation on modeling the strength properties of water-entrained cement-based materials

    DEFF Research Database (Denmark)

    Esteves, L.P.

    2012-01-01

    Water-entrained cement based materials by superabsorbent polymers is a concept that was introduced in the research agenda about a decade ago. However, a recent application in the production of high performance concrete revealed potential weaknesses when the proportioning of this intelligent...... material is not well performed, raising doubts among both academic and industrial society about the usability of superabsorbent polymers in cement-based materials. This work constitutes the baseline tentatively to be used on modeling the compressive strength of SF-modified water-entrained cement...

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

    Science.gov (United States)

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

    2015-01-01

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

  14. The Integration of EIS parameters and bulk matrix characterization in studying reinforced cement-based materials

    NARCIS (Netherlands)

    Koleva, D.A.; Van Breugel, K.

    2012-01-01

    Corrosion in reinforced concrete is a major and costly concern, arising from the higher complexity of involved phenomena on different levels of material science (e.g. electrochemistry, concrete material science) and material properties (macro/micro/ nano). Reinforced cement-based systems (e.g. reinf

  15. The integration of eis parameters and bulk matrix characteristics in studying reinforced cement-based materials

    NARCIS (Netherlands)

    Koleva, D.A.; Van Breugel, K.

    2011-01-01

    Corrosion in reinforced concrete is a major and costly concern, arising from the higher complexity of involved phenomena on different levels of material science (e.g. electrochemistry, concrete material science) and material properties (macro/micro/ nano). Reinforced cement-based systems (e.g. reinf

  16. Influence of silica-based hybrid material on the gas permeability of hardened cement paste

    Science.gov (United States)

    Li, R.; Hou, P.; Xie, N.; Zhou, Z.; Cheng, X.

    2017-03-01

    Surface treatment is one of the most effective ways to elongate the service life of concrete. The surface treatment agents, including organic and inorganic types, have been intensively studied. In this paper, the silica-based hybrid nanocomposite, which take advantages of both organic and inorganic treatment agents, was synthesized and used for surface treatment of hardened cement-based material. The effectiveness of organic and inorganic hybrid nanocomposite was evaluated through investigations on the gas permeability of cement-based materials. The results showed that SiO2/PMHS hybrid nanocomposite can greatly decrease the gas transport properties of hardened cement-based materials and has a great potential for surface treatment of cementitious materials.

  17. Online Monitoring Volume Deformation of Cement-based Materials in Multiple Enviroments

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Comparing and analyzing some volume deformation measuring means for cement-based materials at home and abroad, a continuous online monitor of cement-based material volume deformation in multiple environments is developed. The device is designed based on the environmental simulation technology, micro-distance measuring technology of laser and eddy current, and transmission agent online monitoring the deformation of multi-group samples. This device can be used widely, such as glass, ceramics, walling material, and so on, with high precision, low testing cost, and intellectualization.

  18. Long-term Durability of Cement-based Materials with Very Low w/b

    Institute of Scientific and Technical Information of China (English)

    XIE Youjun; LIU Yunhua; LONG Guangeheng

    2008-01-01

    To investigate the durability, especially the long-term stability of cement-based materials with very low w/b, the air permeability test, carbonation test, capillary absorption rate test and dilation Dotential test were adopted under long-term heat treatment condition. Microstructure of these materials is also analyzed by scannmg electronic microscopy (SEM) and mercury intrusion porosimeter (MIP) in order to further unveil its mechanism and interrelation between microstructure and its properties. The results indicate that in the area investigated, cement-based material with w/b 0.17, like RPC, possesses low porosity and excellent durability. Moreover, its porosity will further decrease under long-term heat treatment compared with normal heat treatment. Its long-term durability is much superior to that of other cement-based materials with w/b 0.25 or 0.35 as high strength concrete (HSC).

  19. Damping Property of a Cement-Based Material Containing Carbon Nanotube

    Directory of Open Access Journals (Sweden)

    Wei-Wen Li

    2015-01-01

    Full Text Available This study aimed to explore the damping property of a cement-based material with carbon nanotube (CNT. In the study, the cement composites with different contents of CNT (0 wt%, 0.033 wt%, 0.066 wt%, and 0.1 wt% were investigated. Logarithmic Decrement method and Dynamic Mechanical Analysis (DMA method were utilized to study the damping property of CNT/cement composite. The influences of CNT on pore size distribution and microstructure of composite were analyzed by Mercury Intrusion Porosimetry (MIP and Scanning Electron Microscopy (SEM, respectively. The experimental results showed that CNT/cement composite presented higher flexural strength index than that of a pure cement paste. Additional CNT could improve the vibration-reduction capacity of cement paste. Furthermore, the experiments proved that CNT could bridge adjacent hydration products and support load transfer within cement matrix, which contributed to the energy dissipation during the loading process.

  20. Early Carbonation Behavior of High-volume Dolomite Powder-cement Based Materials

    Institute of Scientific and Technical Information of China (English)

    YANG Huamei; HE zhen; SHAO Yixin

    2015-01-01

    Combined with DTG analysis, X-Ray diffraction analysis (XRD) andfi eld emission scanning electron microscopy analysis (FSEM) affi liated with energy dispersive spectrometer analysis (EDS), the early hydration and carbonation behavior of cement paste compacts incorporated with 30% of dolomite powder at low water to cement ratio (0.15) was investigated. The results showed that early carbonation curing was capable of developing rapid early strength. It is noted that the carbonation duration should be strictly controlled otherwise subsequent hydration might be hindered. Dolomite powder acted as nuclei of crystallization, resulting in acceleration of products formation and refi nement of products crystal size. Therefore, as for cement-based material, it was found that early carbonation could reduce cement dosages to a large extent and promote rapid strength gain resulting from rapid formation of products, supplemental enhancement due to water release in the reaction of carbonation, and formation of nanometer CaCO3 skeleton network at early age.

  1. RECYCLED WASTE-BASED CEMENT COMPOSITE PATCH MATERIALS FOR RAPID/PERMANENT ROAD RESTORATION.

    Energy Technology Data Exchange (ETDEWEB)

    SUGAMA,T.

    2001-07-31

    Over the past year, KeySpan Energy sponsored a research program at Brookhaven National Laboratory (BNL) aimed at recycling boiler ash (BA) and waste water treatment sludge (WWTS) byproducts generated from Keyspan's power stations into potentially useful materials, and at reducing concurrent costs for their disposal. Also, KeySpan has an interest in developing strategies to explicitly integrate industrial ecology and green chemistry. From our collaborative efforts with Keyspan (Diane Blankenhom Project Manager, and Kenneth Yager), we succeeded in recycling them into two viable products; Pb-exchange adsorbents (PEAs), and high-performance cements (HpCs). These products were made from chemically bonded cement and ceramic (CBC) materials that were synthesized through two-step chemical reaction pathways, acid-base and hydration. Using this synthesis technology, both the WWTS and BA served in acting as solid base reactants, and sodium polyphosphate, [-(-NaPO{sub 3}-)-{sub n}], known as an intermediator of fertilizer, was employed as the acid solution reactant. In addition, two commercial cement additives, Secar No. 51 calcium aluminate cement (CAC) and Type I calcium silicate cement (CSC), were used to improve mechanical behavior and to promote the rate of acid-base reaction of the CBC materials.

  2. Attack of Limestone Cement-based Material Exposed to Magnesium Sulfate Solution at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    ZHANG Fengchen; WU Shengxing; FANG Yonghao; ZHOU Jikai; LI Zhonghua

    2014-01-01

    Limestone in cement could be a source of CO32-needed for thaumasite formation which will result in thaumasite form of sulfate attack (TSA) probably. TSA has more deterioration than ettringite or gypsum form of sulfate attack because it targets the calcium silicate hydrates (C-S-H) which is the main binder phase in all Portland cement-based materials. By means of physical and mechanical property testing as well as erosion phases analysis, magnesium sulfate attack of cement-based material containing 35% limestone powder by mass at 5 ± 2℃is investigated. The compressive strength and flexural strength of mortar specimen immersed in MgSO4 solution increase firstly, then decrease rapidly with the immersing age. Relative dynamic elastic modulus of mortar specimen changes in a phased process. After immersing in MgSO4 solution for 15 weeks, the main erosion phases in paste specimen change from four phases compounds, three phases compounds to two phases compounds from surface to inside. Deterioration course of limestone cement-based material exposed to magnesium sulfate aggressive environment appears progressive damage layer by layer, and every layer probably suffers four stages, which are property strengthening stage, initial degradation stage, thaumasite formation stage and cementation loss stage, respectively.

  3. Modelling Inter-Particle Forces and Resulting Agglomerate Sizes in Cement-Based Materials

    DEFF Research Database (Denmark)

    Kjeldsen, Ane Mette; Geiker, Mette Rica

    2005-01-01

    The theory of inter-particle forces versus external shear in cement-based materials is reviewed. On this basis, calculations on maximum agglomerate size present after the combined action of superplasticizers and shear are carried out. Qualitative experimental results indicate that external shear...... affects the particle size distribution of Mg(OH)2 (used as model material) as well as silica, whereas the addition of superplasticizers affects only the smallest particles in cement and thus primarily acts as water reducers and not dispersers....

  4. Properties of Cement-based Composite Materials under Different Storing Environment Temperature

    Science.gov (United States)

    Weng, T. L.; Weng, S. H.; Cho, S. W.

    2017-02-01

    This study reports on the properties of cement-based composite materials (mortars) under different storing environment temperature, as determined using the accelerated chloride migration test (ACMT). Mortars with a water/cement ratio of 0.45 and five fine aggregate volume fractions (0%, 15%, 30%, 50% and 60%) under various environment temperatures (25, 40, 60 and 80°C) were evaluated according to the passage of chloride ions through the specimens using ACMT. Calculate chloride migration coefficients on the steady-state. Cement-based composite materials with 60 % fine aggregate presented a migration coefficient higher than that of other specimens, whereas mortar with 30 % fine aggregate was lower, due to the effects of dilution and tortuosity.

  5. Microcrack Identification in Cement-Based Materials Using Nonlinear Acoustic Waves

    Science.gov (United States)

    Chen, X. J.; Kim, J.-Y.; Qu, J.; Kurtis, K. E.; Wu, S. C.; Jacobs, L. J.

    2007-03-01

    This paper presents results from tests that use nonlinear acoustic waves to distinguish microcracks in cement-based materials. Portland cement mortar samples prepared with alkali-reactive aggregate were exposed to an aggressive environment to induce cracking were compared to control samples, of the same composition, but which were not exposed to aggressive conditions. Two nonlinear ultrasonic methods were used to characterize the samples, with the aim of identifying the time and extent of microcracking; these techniques were a nonlinear acoustical modulation (NAM) method and a harmonic amplitude relation (HAR) method. These nonlinear acoustic results show that both methods can distinguish damaged samples from undamaged ones, demonstrating the potential of nonlinear acoustic waves to provide a quantitative evaluation of the deterioration of cement-based materials.

  6. Evolution of cement based materials in a repository for radioactive waste and their chemical barrier function

    Energy Technology Data Exchange (ETDEWEB)

    Kienzler, Bernhard; Metz, Volker; Schlieker, Martina; Bohnert, Elke [Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany). Inst. fuer Nukleare Entsorgung (INE)

    2015-07-01

    The use of cementitious materials in nuclear waste management is quite widespread. It covers the solidification of low/intermediate-level liquid as well as solid wastes (e.g. laboratory wastes) and serves as shielding. For both high-level and intermediate-low level activity repositories, cement/concrete likewise plays an important role. It is used as construction material for underground and surface disposals, but more importantly it serves as barrier or sealing material. For the requirements of waste conditioning, special cement mixtures have been developed. These include special mixtures for the solidification of evaporator concentrates, borate binding additives and for spilling solid wastes. In recent years, low-pH cements were strongly discussed especially for repository applications, e.g. (Celine CAU DIT COUMES 2008; Garcia-Sineriz, et al. 2008). Examples for relevant systems are Calcium Silicate Cements (ordinary Portland cement (OPC) based) or Calcium Aluminates Cements (CAC). Low-pH pore solutions are achieved by reduction of the portlandite content by partial substitution of OPC by mineral admixtures with high silica content. The blends follow the pozzolanic reaction consuming Ca(OH){sub 2}. Potential admixtures are silica fume (SF) and fly ashes (FA). In these mixtures, super plasticizers are required, consisting of polycarboxilate or naphthalene formaldehyde as well as various accelerating admixtures (Garcia-Sineriz, et al. 2008). The pH regime of concrete/cement materials may stabilize radionuclides in solution. Newly formed alteration products retain or release radionuclides. An important degradation product of celluloses in cement is iso-saccharin acid. According to Glaus 2004 (Glaus and van Loon 2004), it reacts with radionuclides forming dissolved complexes. Apart from potentially impacting radionuclide solubility limitations, concrete additives, radionuclides or other strong complexants compete for surface sites for sorbing onto cement phases. In

  7. Incinerated sewage sludge ash as alternative binder in cement-based materials

    DEFF Research Database (Denmark)

    Krejcirikova, Barbora; Goltermann, Per; Hodicky, Kamil

    2013-01-01

    it can minimize the need of ash landfill disposal. The objective of this study is to show potential use of incinerated sewage sludge ash (ISSA), an industrial byproduct, as possible binder in cement-based materials. Chemical and mechanical characteristics are presented and compared with results obtained...

  8. Characterization of composite materials based on cement-ceramic powder blended binder

    Science.gov (United States)

    Kulovaná, Tereza; Pavlík, Zbyšek

    2016-06-01

    Characterization of newly developed composite mortars with incorporated ceramic powder coming from precise brick cutting as partial Portland cement replacement up to 40 mass% is presented in the paper. Fine ceramic powder belongs to the pozzolanic materials. Utilization of pozzolanic materials is accompanied by lower request on energy needed for Portland clinker production which generally results in lower production costs of blended binder and lower CO2 emission. In this paper, the ceramic powder is used in cement based mortar composition in amount of 8, 16, 24, 32, and 40 mass% of cement. Chemical composition of ceramic powder is analyzed by X-Ray Fluorescence and X-Ray Diffraction. The particle size distribution of ceramics is accessed on laser diffraction principle. For 28 days cured mortar samples, basic physical and mechanical properties are experimentally determined. The obtained results demonstrate that ceramic powder has potential to replace a part of Portland cement in composition of cement based composites and to reduce negative environmental impact of their production.

  9. Influence of frost damage and sample preconditioning on the porosity characterization of cement based materials using low temperature calorimetry

    DEFF Research Database (Denmark)

    Wu, Min; Fridh, Katja; Johannesson, Björn;

    2015-01-01

    Low temperature calorimetry (LTC) can be used to study the meso-porosity of cement based materials. The influence of frost damage on the meso-porosity determination by LTC was explored on a model material MCM-41 and two cement pastes by conducting repeated cycles of freezing and melting measureme...

  10. The grain grading model and prediction of deleterious porosity of cement-based materials

    Institute of Scientific and Technical Information of China (English)

    FENG Qi; LIU Jun-zhe

    2008-01-01

    The calculating model for the packing degree of spherical particles system was modified. The grain grading model of cement-based materials was established and could be applied in the global grading system as well as in the nano-fiber reinforced system. According to the grain grading model, two kinds of mortar were de-signed by using the global grain materials and nano-fiber materials such as fly ash, silica fume and NR powder.In this paper, the densities of two above systems cured for 90d were tested and the relationship of deleterious porosity and the total porosity of hardened mortar was discussed. Research results show that nano-fiber materialsuch as NR powder can increase the density of cement-based materials. The relationship of deleterious porosity and the total porosity of hardened mortar accords with logarithmic curve. The deleterious porosity and the ration-ality of the grading can be roughly predicted through calculating the packing degree by the grain grading model of cement-based materials.

  11. The influence of iron on water radiolysis in cement-based materials

    Energy Technology Data Exchange (ETDEWEB)

    Bouniol, P., E-mail: pascal.bouniol@cea.f [CEA, DEN, DPC, SCCME, Laboratoire d' Etude du Comportement des Betons et des Argiles, F-91991 Gif-Sur-Yvette (France)

    2010-08-15

    For the time being, assessing the H{sub 2} source term generated by {gamma} irradiated cement-based materials consists of simulating the radiolysis of the pore liquid on the only elementary reactions relating to the decomposition of alkaline water. Such incomplete description does not take into account the impurities contained in the cement and leads to underestimate the production of H{sub 2}. Systematically present in cement materials, iron is likely to influence radiolysis by the disturbance induced on radical chemistry throughout the irradiation period. The faster reactivity of e{sub aq}{sup -} and OH{sup {center_dot}} radicals on Fe(III) and Fe(II), respectively, than on H{sub 2}O{sub 2} and H{sub 2} is responsible for the lower recycling capability of the 'Allen's chain reaction', allowing for H{sub 2} to be preserved in a closed system. A critical review of reaction data about iron complexes (hydroxo-, peroxo-) is presented in order to build up an 'iron' database. Radiolysis simulations in cement porewater in the presence of Fe(OH){sub 3} (considered as a model phase) show, as expected, an increase in the effective production of radiolytic H{sub 2} and the co-existence of exotic valence Fe(IV) with Fe(II) and (III) during the irradiation period ({gamma}).

  12. Sulfate deterioration of cement-based materials examined by x-ray microtomography

    Science.gov (United States)

    Naik, Nikhila N.; Kurtis, Kimberly E.; Wilkinson, Angus P.; Jupe, Andrew C.; Stock, Stuart R.

    2004-10-01

    Sulfate ions present in soil, groundwater, seawater, decaying organic matter, acid rain, and industrial effluent adversely affect the long-term durability of portland cement concrete, but lack of complete understanding of the nature and consequences of sulfate attack hamper our ability to accurately predict performance of concrete in sulfate-rich environments. One impediment to improved understanding of sulfate deterioration of cement-based materials has been the lack of appropriate non-destructive characterization techniques. Laboratory x-ray microtomography affords an opportunity to study in situ the evolution of physical manifestations of damage due to sulfate exposure. The influence of materials selection and mixture parameters - including water-to-cement ratio, cement type, and presence or absence of aggregate, as well as the influence of sulfate exposure conditions, including sulfate and cation type (i.e., Na2SO4 and MgSO4) and concentration - have been examined by microtomography to determine their influence on the rate and character of the sulfate-induced deterioration.

  13. Effects of TEA·HCl hardening accelerator on the workability of cement-based materials

    Science.gov (United States)

    Pan, Wenhao; Ding, Zhaoyang; Chen, Yanwen

    2017-03-01

    The aim of the test is to research the influence rules of TEA·HCl on the workability of cement paste and concrete. Based on the features of the new hardening accelerator, an experimental analysis system were established through different dosages of hardening accelerator, and the feasibility of such accelerator to satisfy the need of practical engineering was verified. The results show that adding of the hardening accelerator can accelerate the cement hydration, and what’s more, when the dosage was 0.04%, the setting time was the shortest while the initial setting time and final setting time were 130 min and 180 min, respectively. The initial fluidity of cement paste of adding accelerator was roughly equivalent compared with that of blank. After 30 min, fluidity loss would decrease with the dosage increasing, but fluidity may increase. The application of the hardening accelerator can make the early workability of concrete enhance, especially the slump loss of 30 min can improve more significantly. The bleeding rate of concrete significantly decreases after adding TEA·HCl. The conclusion is that the new hardening accelerator can meet the need of the workability of cement-based materials in the optimum dosage range.

  14. Sequestration of phosphorus from wastewater by cement-based or alternative cementitious materials.

    Science.gov (United States)

    Wang, Xinjun; Chen, Jiding; Kong, Yaping; Shi, Xianming

    2014-10-01

    Cement-based and alternative cementitious materials were tested in the laboratory for their capability of removing phosphate from wastewater. The results demonstrated that both Langmuir and Freundlich adsorption isotherms were suitable for describing the adsorption characteristics of these materials. Among the four types of filter media tested, the cement-based mortar A has the highest value of maximum adsorption (30.96 mg g(-1)). The P-bonding energy (KL) and adsorption capacity (K) exhibited a positive correlation with the total content of Al2O3 and Fe2O3 in each mortar. The maximum amount of P adsorbed (Qm) and adsorption intensity (1/n) exhibited a positive correlation with the CaO content in each mortar. For three of them, the P-removal rates were in excess of 94 percent for phosphorus concentrations ranging from 20 to 1000 mg L(-1). The underlying mechanisms were examined using field emission scanning microscopy (FESEM), coupled with energy-dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction (XRD). The results reveal that the removal of phosphate predominantly followed a precipitation mechanism in addition to weak physical interactions between the surface of adsorbent filter media and the metallic salts of phosphate. The use of cement-based or alternative cementitious materials in the form of ground powder shows great promise for developing a cost-effective and environmentally sustainable technology for P-sequestration and for wastewater treatment.

  15. Simulation of expansion in cement based materials subjected to external sulfate attack

    Directory of Open Access Journals (Sweden)

    O.A. Hodhod

    2014-03-01

    Full Text Available The standard test for length change in hydraulic-cement mortars exposed to sulfate solution, ASTM C1012-95, has been widely used by researchers to study the sulfate resistance of cement based materials. However, there are deficiencies in this test method including lengthy measuring period, insensitivity of the measurement tool to sulfate attack, effect of curing and pH change. So, in this study, a model will be built by artificial neural networks (ANNs to simulate this test and overcome these defects. This model will deal with different types of cement in the presence of blast-furnace slag (GGBFS or fly ash (PFA. From the results of simulations, it is possible to understand the impact of cement chemistry and these two types of additions on resistance of sulfate attack more readily, faster, and accurately. Such an understanding improves the decision making process in every stage of construction and maintenance and will help in better administration of resources.

  16. Gas permeability of cement based materials; Etude de la permeabilite au gaz des materiaux cimentaires

    Energy Technology Data Exchange (ETDEWEB)

    Galle, Ch.; Pin, M. [CEA Saclay, Dept. d' Entreposage et de Stockage des Dechets (DCC/DESD/SESD), 91 - Gif-sur-Yvette (France); Daian, J.F. [Universite Joseph-Fourier, Grenoble I, (INPG/CNRS/IRD), 38 (France)

    2000-07-01

    The study of the permeability of cement based materials is an important issue for their transport properties, which are good indicators of their durability. Studies were undertaken to acquire experimental data and to model the gas permeability of cement based materials. Among many parameters like cement type, water-cement ratio (w/c), curing, etc, the degree of water saturation and microstructural properties are the two main parameters controlling the ability of such type of materials to transport gas. It is well known that the higher the water saturation, the lower the gas permeability. Under pressure, gas will be also transported through the biggest pore accesses. It must be emphasized that the w/c ratio is the fundamental parameter for cement based materials. This ratio controls the hydration process and hence the material porosity. Gas permeability was calculated with Darcy law as modified by the Hagen-Poiseuille formula (1). Various materials were investigated: pure cement pastes prepared with different types of cement (CEM I-OPC, CEM V-BFS-PFA) and various w/c ratios, and industrial concretes. After curing, the samples were stored under controlled relative humidity conditions using saline solutions to reach a stable hydric state. N{sup 2} gas permeability tests were then performed with a Hassler apparatus. The microstructural properties of CEM I and CEM V materials are given in Figure 2. Examples of experimental results obtained with pure pastes are shown in Figure 3. A comparative example of paste and concrete data is provided in Figure 4. It was experimentally observed that gas permeability is extremely sensitive to material water saturation: up to five orders of magnitude of variation (between 10{sup -16} and 10{sup -21} m{sup 2} on average) for water saturations from a few % to 100%. The higher the w/c ratio, the higher the gas permeability. CEM I pastes are also less permeable than CEM V pastes. The higher total porosity effect of CEM V materials is not

  17. Non destructive determination of the free chloride content in cement based materials

    Energy Technology Data Exchange (ETDEWEB)

    Elsener, B. [Department of Inorganic and Analytical Chemistry, University of Cagliari, I-09128 Cagliari (Italy); Institute of Materials Chemistry and Corrosion, Swiss Federal Institute of Technology, ETH Hoenggerberg, CH-8093 Zuerich (Switzerland); Zimmermann, L.; Boehni, H. [Institute of Materials Chemistry and Corrosion, Swiss Federal Institute of Technology, ETH Hoenggerberg, CH-8093 Zuerich (Switzerland)

    2003-06-01

    A non-destructive chloride sensitive sensor element for use in cement based porous materials is presented. The sensor element determines the activity of the free chloride ions in solutions and in porous cement based materials such as cement paste, mortar or concrete. The calibration in synthetic pore solution showed a response according to Nernst law over three decades of chloride concentration. The sensor element has shown excellent reproducibility and long term stability. The sensor element has been used to monitor the chloride uptake into mortar specimens. The results show a good agreement between the free chloride content determined by the sensor and by pore water expression. Applications in monitoring of reinforced concrete structures and their limitations are discussed. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] In der vorliegenden Arbeit wird ein Chloridsensor zur zerstoerungsfreien Erfassung des Chloridgehalts in zementoesen Materialien beschrieben. Der Sensor bestimmt die Aktivitaet der freien Chloridionen in Loesungen und in Zementstein, Moertel oder Beton. Die Kalibrierungskurve in synthetischer Betonporenloesung zeigt das erwartete Nernst'sche Verhalten ueber mehr als drei Konzentrationsdekaden. Der Sensor weist eine sehr hohe Reproduzierbarkeit und Langzeitstabilitaet auf. Der Chloridsensor wurde eingesetzt, um das Eindringen der Chloridionen in Moertelpruefkoerpern zu untersuchen. Ein Vergleich der Chloridkonzentration bestimmt durch Auspressen der Porenloesung am Ende der Versuche mit den von Sensoren bestimmten Chloridkonzentration zeigt eine sehr gute Uebereinstimmung. Praktische Anwendungen und die Einsatzgrenzen des Sensors werden diskutiert. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  18. Evaluation of frost damage in cement-based materials by a nonlinear elastic wave technique

    Science.gov (United States)

    Eiras, J. N.; Kundu, T.; Popovics, J. S.; Monzó, J.; Soriano, L.; Payá, J.

    2014-03-01

    Frost resistance of concrete is a major concern in cold regions. RILEM (International union of laboratories and experts in construction materials, systems and structures) recommendations provide two alternatives for evaluating frost damage by nondestructive evaluation methods for concrete like materials. The first method is based on the ultrasonic pulse velocity measurement, while the second alternative technique is based on the resonant vibration test. In this study, we monitor the frost damage in Portland cement mortar samples with water to cement ratio of 0.5 and aggregate to cement ratio of 3. The samples are completely saturated by water and are frozen for 24 hours at -25°C. The frost damage is monitored after 0, 5, 10, 15 and 20 freezing-thawing cycles by nonlinear impact resonance acoustic spectroscopy (NIRAS). The results obtained are compared with those obtained by resonant vibration tests, the second alternative technique recommended by RILEM. The obtained results show that NIRAS is more sensitive to early stages of damage than the standard resonant vibration tests.

  19. Effects of Leaching Behavior of Calcium Ions on Compression and Durability of Cement-based Materials with Mineral Admixtures

    Directory of Open Access Journals (Sweden)

    Wei-Ting Lin

    2013-05-01

    Full Text Available Leaching of calcium ions increases the porosity of cement-based materials, consequently resulting in a negative effect on durability since it provides an entry for aggressive harmful ions, causing reinforcing steel corrosion. This study investigates the effects of leaching behavior of calcium ions on the compression and durability of cement-based materials. Since the parameters influencing the leaching behavior of cement-based materials are unclear and diverse, this paper focuses on the influence of added mineral admixtures (fly ash, slag and silica fume on the leaching behavior of calcium ions regarding compression and durability of cemented-based materials. Ammonium nitrate solution was used to accelerate the leaching process in this study. Scanning electron microscopy, X-ray diffraction analysis, and thermogravimetric analysis were employed to analyze and compare the cement-based material compositions prior to and after calcium ion leaching. The experimental results show that the mineral admixtures reduce calcium hydroxide quantity and refine pore structure through pozzolanic reaction, thus enhancing the compressive strength and durability of cement-based materials.

  20. Quantification of uncertainty of experimental measurement in leaching test on cement-based materials.

    Science.gov (United States)

    Coutand, M; Cyr, M; Clastres, P

    2011-10-01

    When mineral wastes are reused in construction materials, a current practice is to evaluate their environmental impact using standard leaching test. However, due to the uncertainty of the measurement, it is usually quite difficult to estimate the pollutant potential compared to other materials or threshold limits. The aim of this paper is to give a quantitative evaluation of the uncertainty of leachate concentrations of cement-based materials, as a function of the number of test performed. The relative standard deviations and relative confidence intervals are determined using experimental data in order to give a global evaluation of the uncertainty of leachate concentrations (determination of total relative standard deviation). Various combinations were realized in order to point out the origin of large dispersion of the results (determination of relative standard deviation linked to analytical measured and to leaching procedure), generalisation was suggested and the results were compared to literature. An actual example was given about the introduction of residue (meat and bone meal bottom ash--MBM-BA) in mortar, leaching tests were carried out on various samples with and without residue MBM-BA. In conclusion large dispersion were observed and mainly due to heterogeneity of materials. So heightened attention needed to analyse leaching result on cement-based materials and further more other tests (e.g. ecotoxicology) should be performed to evaluate the environmental effect of these materials.

  1. Numerical modelling of porous cement-based materials by superabsorbent polymers

    DEFF Research Database (Denmark)

    Viejo, Ismael; Esteves, Luis Pedro; Laspalas, Manuel;

    2016-01-01

    The development of new cementitious materials raises new challenges with regard to structural design. One of the potential applications of superabsorbent polymers (SAP) is to deliver well-defined porosity to cement systems. This is particularly interesting for the development of porous cement...

  2. Surface and subsurface damage detection in cement-based materials using electrical resistance tomography

    Science.gov (United States)

    Ruan, T.; Poursaee, A.

    2016-04-01

    Cement-based materials are widely used in infrastructure facilities. However, often the degradation of structures leads to the failures earlier than designed service life. Thus, non-destructive testing techniques are urgently needed to evaluate the health information of the structures. In this paper, the implementation of Electrical Resistance Tomography (ERT) was investigated. This low cost, radiation free and easy to perform modality is based on measuring the electrical properties of the material under test and using that to evaluate the existence of defects in that material. It uses a set of boundary potentials and injected current to reconstruct the conductivity distribution. An automatic measurement system was developed and surface damages as well as subsurface damages on mortar specimens were investigated. The reconstructed images were capable to show the presence and the location of the damages.

  3. Effect of carbonation on the linear and nonlinear dynamic properties of cement-based materials

    Science.gov (United States)

    Eiras, Jesus N.; Kundu, Tribikram; Popovics, John S.; Monzó, José; Borrachero, María V.; Payá, Jordi

    2016-01-01

    Carbonation causes a physicochemical alteration of cement-based materials, leading to a decrease of porosity and an increase of material hardness and strength. However, carbonation will decrease the pH of the internal pore water solution, which may depassivate the internal reinforcing steel, giving rise to structural durability concerns. Therefore, the proper selection of materials informed by parameters sensitive to the carbonation process is crucial to ensure the durability of concrete structures. The authors investigate the feasibility of using linear and nonlinear dynamic vibration response data to monitor the progression of the carbonation process in cement-based materials. Mortar samples with dimensions of 40×40×160 mm were subjected to an accelerated carbonation process through a carbonation chamber with 55% relative humidity and >95% of CO2 atmosphere. The progress of carbonation in the material was monitored using data obtained with the test setup of the standard resonant frequency test (ASTM C215-14), from a pristine state until an almost fully carbonated state. Linear dynamic modulus, quality factor, and a material nonlinear response, evaluated through the upward resonant frequency shift during the signal ring-down, were investigated. The compressive strength and the depth of carbonation were also measured. Carbonation resulted in a modest increase in the dynamic modulus, but a substantive increase in the quality factor (inverse attenuation) and a decrease in the material nonlinearity parameter. The combined measurement of the vibration quality factor and nonlinear parameter shows potential as a sensitive measure of material changes brought about by carbonation.

  4. In Vitro Cytotoxicity of Calcium Silicate-Based Endodontic Cement as Root-End Filling Materials

    Directory of Open Access Journals (Sweden)

    Selen Küçükkaya

    2016-01-01

    Full Text Available The aim of this study was to evaluate the cytotoxicity of three types of calcium silicate-based endodontic cement after different incubation periods with human periodontal ligament fibroblasts. Human periodontal ligament fibroblasts were cultured from extracted third molars and seeded in 96-well plates. MTA, calcium enriched mixture (CEM cement, and Biodentine were prepared and added to culture insert plates which were immediately placed into 96-well plates containing cultured cells. After incubation periods of 24, 48, and 72 hours, cell viability was determined with WST-1 assay. Data were analysed statistically by ANOVA with repeated measures and Bonferroni tests. There was no significant difference in cell viability amongst the test materials after each incubation period (P>0.05. MTA and CEM presented more than 90% cell viability after 24 and 48 hours of incubation and showed statistically significant decrease in cell viability after 72 hours of incubation (P<0.05. Biodentine showed significantly less cell viability (73% after 24 hours of incubation, whereas more than 90% cell viability was seen after 48 and 72 hours of incubation (P<0.05. Despite the significant changes in cell viability over time, materials presented similar cytotoxicity profile. Biodentine and CEM can be considered as alternative materials for root-end surgery procedures.

  5. High Water Content Material Based on Ba-Bearing Sulphoaluminate Cement

    Institute of Scientific and Technical Information of China (English)

    CHANG Jun; CHENG Xin; LU Lingchao; HUANG Shifeng; YE Zhengmao

    2005-01-01

    A new type of high water content material which is made up of two pastes is prepared, one is made from lime and gypsum, and another is based on Ba-bearing stdphoaluminate cement. It has excellent properties such as slow single paste solidifing,fast double pastes solidifing,fast coagulating and hardening, high early strength, good suspension property at high W/C ratio and low cost. Meanwhile, the properties and hydration mechanism of the material were analyzed by using XRD , DTA- TG and SEM. The hydrated products of new type of high water content material are Ba-bearing ettringite, BaSO4 , aluminum gel and C-S-H gel.

  6. Multi-scale Modeling of the Effective Chloride lon Diffusion Coefficient in Cement-based Composite Materials

    Institute of Scientific and Technical Information of China (English)

    SUN Guowen; SUN Wei; ZHANG Yunsheng; LIU Zhiyong

    2012-01-01

    N-layered spherical inclusions model was used to calculate the effective diffusion coefficient of chloride ion in cement-based materials by using multi-scale method and then to investigate the relationship between the diffusivity and the microstructure of cement-basted materials where the microstructure included the interfacial transition zone (ITZ) between the aggregates and the bulk cement pastes as well as the microstructure of the bulk cement paste itself.For the convenience of applications,the mortar and concrete were considered as a four-phase spherical model,consisting of cement continuous phase,dispersed aggregates phase,interface transition zone and their homogenized effective medium phase.A general effective medium equation was estabhshed to calculate the diffusion coefficient of the hardened cement paste by considering the microstructure.During calculation,the tortuosity (n) and eonstrictivity factors (Ds/D0) of pore in the hardened pastes are n≈3.2,Ds/D0=1.0× 10-4 respectively from the test data.The calculated results using the n-layered spherical inclusions model are in good agreement with the experimental results; The effective diffusion coefficient of ITZ is 12 times that of the bulk cement for mortar and 17 times for concrete due to the difference between particle size distribution and the volume fraction of aggregates in mortar and concrete.

  7. Effect of Fly Ash on TSA Resistance of Cement-based Material

    Institute of Scientific and Technical Information of China (English)

    ZHANG Fengchen; MA Baoguo; WU Shengxing; ZHOU Jikai

    2011-01-01

    Thaumasite form of sulfate attack (TSA) is a major concern in evaluating durability of concrete structures subjected to sulfate and carbonate ions. By means of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM),and energy dispersive spectrum (EDS)as well as Raman spectra of erosion substances, effect of fly ash on TSA resistance of Portland cement-based material were investigated. Immersed in magnesium sulfate solution with 33 800 ppm mass concentration of SO42- at 5±2 ℃ for 15 weeks, ratio of compressive strength loss decreased as binder replacement ratio of fly ash increased. Furthermore, when binder replacement of fly ash was 60%, compressive strength increased. When thaumasite came into being in samples with 0, 15% binder replacement ratio of fly ash, ettringite and gypsum appeared in those with 30%, 45%, 60% binder replacement ratio of fly ash. Results mentioned above showed that fly ash can restrain formation of thaumasite and improve TSA resistance of Portland cement-based material sufficiently.

  8. The effect of temperature rise on microstructural properties of cement-based materials: correlation of experimental data and a simulation approach

    NARCIS (Netherlands)

    Susanto, A.; Koleva, D.A.; Van Breugel, K.

    2015-01-01

    This work reports on the influence of stray current flow on temperature rise in hardening cement-based materials and consequently altered cement hydration. To simulate stray current, different levels of electrical current were applied to cement paste and mortar specimens immediately after casting. I

  9. In Vitro Cytotoxicity of Calcium Silicate-Based Endodontic Cement as Root-End Filling Materials.

    Science.gov (United States)

    Küçükkaya, Selen; Görduysus, Mehmet Ömer; Zeybek, Naciye Dilara; Müftüoğlu, Sevda Fatma

    2016-01-01

    The aim of this study was to evaluate the cytotoxicity of three types of calcium silicate-based endodontic cement after different incubation periods with human periodontal ligament fibroblasts. Human periodontal ligament fibroblasts were cultured from extracted third molars and seeded in 96-well plates. MTA, calcium enriched mixture (CEM) cement, and Biodentine were prepared and added to culture insert plates which were immediately placed into 96-well plates containing cultured cells. After incubation periods of 24, 48, and 72 hours, cell viability was determined with WST-1 assay. Data were analysed statistically by ANOVA with repeated measures and Bonferroni tests. There was no significant difference in cell viability amongst the test materials after each incubation period (P > 0.05). MTA and CEM presented more than 90% cell viability after 24 and 48 hours of incubation and showed statistically significant decrease in cell viability after 72 hours of incubation (P Biodentine showed significantly less cell viability (73%) after 24 hours of incubation, whereas more than 90% cell viability was seen after 48 and 72 hours of incubation (P Biodentine and CEM can be considered as alternative materials for root-end surgery procedures.

  10. Measurement with corrugated tubes of early-age autogenous shrinkage of cement-based material

    DEFF Research Database (Denmark)

    Tian, Qian; Jensen, Ole Mejlhede

    2009-01-01

    The use of a special corrugated mould enables transformation of volume strain into horizontal, linear strain measurement in the fluid stage. This allows continuous measurement of the autogenous shrinkage of cement-based materials since casting, and also effectively eliminates unwanted influence...... on the measuring results from gravity, temperature variation and mould restraint. In this paper the principle of the corrugated tube measurement is described. A systematic study was carried out on the influence on the measuring results of the material properties, size effects and encapsulated air in the corrugated...... tube. The experimental results show that there is a minor influence on the measuring results of the stiffness and size of the plastic tube as well as of the encapsulated air. However, the influence decreases with the hardening process and becomes negligible a few hours after final set....

  11. Recommended method for measurement of absorbency of superabsorbent polymers in cement-based materials

    DEFF Research Database (Denmark)

    Esteves, Luis Pedro

    2015-01-01

    so that the properties of concrete with superabsorbent polymers can be better controlled in practice. In this paper, a technique that can be potentially used as a standard method is developed. The method is based on a measurement technique validated through an international standard procedure......The application of superabsorbent polymers in concrete technology is now becoming a reality in several places in the world. Independently of the specific technical application involving any of the hydrogels, the design of cement-based materials requires that the knowledge on the absorbency......—laser diffraction particle size analysis, and it allows an easy and reliable measurement of the absorbency of superabsorbent polymers. It is shown in detail how both the definition of the exposure liquid and the definition of the system of SAP particles can be selected so that absorbency can be experimentally...

  12. Study on Strength and Microstructure of Cement-Based Materials Containing Combination Mineral Admixtures

    Directory of Open Access Journals (Sweden)

    Meijuan Rao

    2016-01-01

    Full Text Available The compressive strength of complex binders containing two or three blended mineral admixtures in terms of glass powder (GP, limestone powder (LP, and steel slag powder (SP was determined by a battery solution type compressive testing machine. The morphology and microstructure characteristics of complex binder hydration products were also studied by microscopic analysis methods, such as XRD, TG-DTA, and SEM. The mechanical properties of the cement-based materials were analyzed to reveal the most appropriate mineral admixture type and content. The early sample strength development with GP was very slow, but it rapidly grew at later stages. The micro aggregate effect and pozzolanic reaction mutually occurred in the mineral admixture. In the early stage, the micro aggregate effect reduced paste porosity and the small particles connected with the cement hydration products to enhance its strength. In the later stage, the pozzolanic reaction of some components in the complex powder occurred and consumed part of the calcium hydroxide to form C-S-H gel, thus improving the hydration environment. Also, the produced C-S-H gel made the structure more compact, which improved the structure’s strength.

  13. Cementing a wellbore using cementing material encapsulated in a shell

    Energy Technology Data Exchange (ETDEWEB)

    Aines, Roger D.; Bourcier, William L.; Duoss, Eric B.; Floyd, III, William C.; Spadaccini, Christopher M.; Vericella, John J.; Cowan, Kenneth Michael

    2017-03-14

    A system for cementing a wellbore penetrating an earth formation into which a pipe extends. A cement material is positioned in the space between the wellbore and the pipe by circulated capsules containing the cement material through the pipe into the space between the wellbore and the pipe. The capsules contain the cementing material encapsulated in a shell. The capsules are added to a fluid and the fluid with capsules is circulated through the pipe into the space between the wellbore and the pipe. The shell is breached once the capsules contain the cementing material are in position in the space between the wellbore and the pipe.

  14. Cementing a wellbore using cementing material encapsulated in a shell

    Science.gov (United States)

    Aines, Roger D.; Bourcier, William L.; Duoss, Eric B.; Spadaccini, Christopher M.; Cowan, Kenneth Michael

    2016-08-16

    A system for cementing a wellbore penetrating an earth formation into which a pipe extends. A cement material is positioned in the space between the wellbore and the pipe by circulated capsules containing the cement material through the pipe into the space between the wellbore and the pipe. The capsules contain the cementing material encapsulated in a shell. The capsules are added to a fluid and the fluid with capsules is circulated through the pipe into the space between the wellbore and the pipe. The shell is breached once the capsules contain the cementing material are in position in the space between the wellbore and the pipe.

  15. Prediction of SEM–X-ray images’ data of cement-based materials using artificial neural network algorithm

    Directory of Open Access Journals (Sweden)

    Ashraf Ragab Mohamed

    2014-09-01

    Full Text Available Recent advances of computational capabilities have motivated the development of more sophisticated models to simulate cement-based hydration. However, the input parameters for such models, obtained from SEM–X-ray image analyses, are quite complicated and hinder their versatile application. This paper addresses the utilization of the artificial neural networks (ANNs to predict the SEM–X-ray images’ data of cement-based materials (surface area fraction and the cement phases’ correlation functions. ANNs have been used to correlate these data, already obtained for 21 types of cement, to basic cement data (cement compounds and fineness. Two approaches have been proposed; the ANN, and the ANN-regression method. Comparisons have shown that the ANN proves effectiveness in predicting the surface area fraction, while the ANN-regression is more computationally suitable for the correlation functions. Results have shown good agreement between the proposed techniques and the actual data with respect to hydration products, degree of hydration, and simulated images.

  16. PMMA-based composite materials with reactive ceramic fillers: IV. Radiopacifying particles embedded in PMMA beads for acrylic bone cements.

    Science.gov (United States)

    Abboud, M; Casaubieilh, L; Morvan, F; Fontanille, M; Duguet, E

    2000-01-01

    New acrylic bone cements were prepared from alumina particles previously treated by 3-(trimethoxysilyl)propylmethacrylate (gamma-MPS) and embedded in poly(methylmethacrylate-co-ethylacrylate) beads with about 7 mol% of ethyl acrylate repeating units. The encapsulation was performed through a conventional suspension polymerization process. The influence of (i) the concentration of the dispersion stabilizer and (ii) the alumina content upon the shape, size, and size distribution of the acrylic beads was studied. Cements were prepared from each batch by hand-mixing alumina-filled acrylic beads with a liquid monomer mixture containing methyl methacrylate, n-butyl methacrylate, and N,N-dimethyl-p-toluidine. Benzoyl peroxide was previously added to the solid part. The powder-to-liquid ratio was equal to 2 for each formulation. Compressive strength of cured cement decreases with alumina content, whereas compressive modulus remains roughly constant. These results are in contradiction to those obtained for cements based on a mixture of gamma-MPS-treated alumina and unfilled acrylic beads. Nevertheless, they are interpreted in terms of alumina arrangement in the cement. In the first case, alumina particles contribute to the reinforcement of the dispersed acrylic phase, with poor benefits for the whole materials. In the second case, they allow the reinforcement of the continuous acrylic phase and, therefore, the cement's one.

  17. Advanced Nanoscale Characterization of Cement Based Materials Using X-Ray Synchrotron Radiation: A Review

    KAUST Repository

    Chae, Sejung R.

    2013-05-22

    We report various synchrotron radiation laboratory based techniques used to characterize cement based materials in nanometer scale. High resolution X-ray transmission imaging combined with a rotational axis allows for rendering of samples in three dimensions revealing volumetric details. Scanning transmission X-ray microscope combines high spatial resolution imaging with high spectral resolution of the incident beam to reveal X-ray absorption near edge structure variations in the material nanostructure. Microdiffraction scans the surface of a sample to map its high order reflection or crystallographic variations with a micron-sized incident beam. High pressure X-ray diffraction measures compressibility of pure phase materials. Unique results of studies using the above tools are discussed-a study of pores, connectivity, and morphology of a 2,000 year old concrete using nanotomography; detection of localized and varying silicate chain depolymerization in Al-substituted tobermorite, and quantification of monosulfate distribution in tricalcium aluminate hydration using scanning transmission X-ray microscopy; detection and mapping of hydration products in high volume fly ash paste using microdiffraction; and determination of mechanical properties of various AFm phases using high pressure X-ray diffraction. © 2013 The Author(s).

  18. Self-healing phenomena in cement-based materials state-of-the-art report of RILEM Technical Committee 221-SHC Self-Healing Phenomena in Cement-Based Materials

    CERN Document Server

    Tittelboom, Kim; Belie, Nele; Schlangen, Erik

    2013-01-01

    Self-healing materials are man-made materials which have the built-in capability to repair damage. Failure in materials is often caused by the occurrence of small microcracks throughout the material. In self-healing materials phenomena are triggered to counteract these microcracks. These processes are ideally triggered by the occurrence of damage itself. Thus far, the self-healing capacity of cement-based materials has been considered as something "extra". This could be called passive self-healing, since it was not a designed feature of the material, but an inherent property of it. Centuries-old buildings have been said to have survived these centuries because of the inherent self-healing capacity of the binders used for cementing building blocks together. In this State-of-the-Art Report a closer look is taken at self-healing phenomena in cement-based materials. It is shown what options are available to design for this effect rather than have it occur as a "coincidental extra".

  19. Electrical behavior of structural cement-based materials: Science and applications

    Science.gov (United States)

    Cao, Jingyao

    The electrical behavior of cement-based structural materials was studied for damage/microstructural evolution investigation, electromagnetic interference (EMI) shielding, fiber dispersion characterization, and for understanding of polarization, depolarization, the role of moisture, and the effects of aggregates and silica fume. Monitoring was performed in real time during static loading, dynamic loading creep, freeze-thaw cycling and drying shrinkage. It involved the use of the cement-based material itself as the sensor and was based on the dependence of the DC electrical resistivity on the damage/microstructural condition. The volume resistivity was the attribute used for monitoring interfaces in the material. The interfaces included that between steel rebar and concrete and that between old concrete and new concrete. The resistivity increased upon damage infliction or damage aggravation, but decreased upon damage diminution. In addition, it increased during microstructural change, which occurred even in the early stage of compressive elastic deformation. An increase in compressive strain rate was found to cause the fractional increase in resistivity to be less at the same strain, because micro structural change took time. The fractional increase in resistivity per unit strain was the parameter used to describe the extent of strain-induced micro structural change. Its value was much higher during creep or drying shrinkage than during static loading up to failure, due to the long time associated with creep and the hydration that accompanied drying shrinkage. Freeze-thaw cycling caused damage, which progressed cycle by cycle and occurred in each cycle more significantly upon cooling than upon heating. The presence of sand increased the fractional change in resistivity at the same drying shrinkage strain, whereas the presence of silica fume decreased the fractional change in resistivity at the same shrinkage strain. The presence of sand or silica fume also enhanced

  20. 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...

  1. Experimental evidence of the influence of iron on pore water radiolysis in cement-based materials

    Energy Technology Data Exchange (ETDEWEB)

    Bouniol, P., E-mail: pascal.bouniol@cea.fr [CEA, DEN, DPC, SECR, Laboratoire d’Etude du Comportement des Bétons et des Argiles, F-91991 Gif-Sur-Yvette (France); Muzeau, B. [CEA, DEN, DPC, SECR, Laboratoire d’Etude du Comportement des Bétons et des Argiles, F-91991 Gif-Sur-Yvette (France); Dauvois, V. [CEA, DEN, DPC, SECR, Laboratoire de Radiolyse et de la Matière Organique, F-91991 Gif-Sur-Yvette (France)

    2013-06-15

    Hydrated tricalcium silicate based cement pastes or mixes, with the addition or not of amorphous iron oxyhydroxide, were irradiated for 1 year in a closed system (γ radiation) with the aim of provoking radiolysis of the alkaline pore solution (pH > 13). The data collected (on-line monitoring of the total pressure and the H{sub 2} content in 500 cm{sup 3} mini-containers irradiated at 45 °C and 1.07 kGy/h with V{sub gas}/V{sub paste} ≈ 1) enable us to conclude that the addition of 1% of FeOOH{sub am} gives rise to about 26% of additional residual H{sub 2} after 1 year. This result appears to validate the hypothesis of a partial mobilisation of the e{sub aq}{sup -} and O{sup ·−} radicals in a continuous process of Fe(III) ↔ Fe(II) oxidation–reduction, at the expense of their action within the Allen type reaction chain that is responsible for the recycling of H{sub 2}. Despite the complexity of the porous material, the simulation of the experiment with the CHEMSIMUL application leads to a result that is quite close, and stresses the importance of the kinetic coupling between gas transport in the porous material and the reaction system.

  2. Modelling the effect of electrical current flow on the hydration process of cement-based materials

    NARCIS (Netherlands)

    Susanto, A.; Koleva, D.A.; Van Breugel, K.; Koenders, E.A.B.

    2014-01-01

    Stray current is essentially an electrical current “leakage” from metal conductors and electrical installations. When it flows through cement-based systems, electrical energy is converted to thermal energy that causes increasing temperature due to Joule heating phenomena. The aim of this paper is to

  3. X-ray microtomography for fracture studies in cement-based materials

    Science.gov (United States)

    Landis, Eric N.; Keane, Denis T.

    1999-09-01

    In this study we are interested in microstructure-property relationships in portland cement-based materials. Specifically, we are interested in relating microfracture and damage to bulk mechanical properties. To do this a high resolution three-dimensional scanning technique called x-ray microtomography was applied to measure internal damage and crack growth in small mortar cylinders loaded in uniaxial compression. Synchrotron-based microtomography allows us to resolve internal features that are only a few microns in size. Multiple tomographic scans were made of the same specimen at different levels of deformation, the deformation being applied through a custom built loading frame. Three-dimensional image analysis was used to measure internal crack growth during each deformation increment. Measured load-deformation curves were used to calculate the non-recoverable work of load on the specimen. Incremental non-recoverable work of load was related to measured incremental change in crack surface area to estimate work-of-fracture in three dimensions. Initial results indicate a nearly constant work-of-fracture for the early stages of crack growth. These results show that basic fracture mechanics principles may be applied to concrete in compression, however we must think in terms of 3D multiple crack systems rather than traditional 2D single crack systems.

  4. Microstructure, characterizations, functionality and compressive strength of cement-based materials using zinc oxide nanoparticles as an additive

    Energy Technology Data Exchange (ETDEWEB)

    Nochaiya, Thanongsak [Department of Physics, Faculty of Science, Naresuan University, Phitsanulok 65000 (Thailand); Sekine, Yoshika [Department of Chemistry, School of Science, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Choopun, Supab [Applied Physics Research Laboratory, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Chaipanich, Arnon, E-mail: arnon.chaipanich@cmu.ac.th [Advanced Cement-Based Materials Research Unit, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2015-05-05

    Highlights: • Nano zinc oxide was used as an additive material. • Microstructure and phase characterization of pastes were characterized using SEM and XRD. • TGA and FTIR were also used to determine the hydration reaction. • Compressive strength of ZnO mixes was found to increase at 28 days. - Abstract: Zinc oxide nanoparticles as a nanophotocatalyst has great potential for self-cleaning applications in concrete structures, its effects on the cement hydration, setting time and compressive strength are also important when using it in practice. This paper reports the effects of zinc oxide nanoparticles, as an additive material, on properties of cement-based materials. Setting time, compressive strength and porosity of mortars were investigated. Microstructure and morphology of pastes were characterized using scanning electron microscope and X-ray diffraction (XRD), respectively. Moreover, thermal gravimetric analysis (TGA) and Fourier-transform infrared spectrometer (FTIR) were also used to determine the hydration reaction. The results show that Portland cement paste with additional ZnO was found to slightly increase the water requirement while the setting time presented prolongation period than the control mix. However, compressive strength of ZnO mixes was found to be higher than that of PC mix up to 15% (at 28 days) via filler effect. Microstructure, XRD and TGA results of ZnO pastes show less hydration products before 28 days but similar at 28 days. In addition, FTIR results confirmed the retardation when ZnO was partially added in Portland cement pastes.

  5. Characterisation and use of biomass fly ash in cement-based materials.

    Science.gov (United States)

    Rajamma, Rejini; Ball, Richard J; Tarelho, Luís A C; Allen, Geoff C; Labrincha, João A; Ferreira, Victor M

    2009-12-30

    This paper presents results about the characterisation of the biomass fly ashes sourced from a thermal power plant and from a co-generation power plant located in Portugal, and the study of new cement formulations incorporated with the biomass fly ashes. The study includes a comparative analysis of the phase formation, setting and mechanical behaviour of the new cement-fly ash formulations based on these biomass fly ashes. Techniques such as X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), thermal gravimetric and differential thermal analysis (TG/DTA), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and environmental scanning electron spectroscopy (ESEM) were used to determine the structure and composition of the formulations. Fly ash F1 from the thermal power plant contained levels of SiO(2), Al(2)O(3) and Fe(2)O(3) indicating the possibility of exhibiting pozzolanic properties. Fly ash F2 from the co-generation plant contained a higher quantity of CaO ( approximately 25%). The fly ashes are similar to class C fly ashes according to EN 450 on the basis of chemical composition. The hydration rate and phase formation are greatly dependant on the samples' alkali content and water to binder (w/b) ratio. In cement based mortar with 10% fly ash the basic strength was maintained, however, when 20% fly ash was added the mechanical strength was around 75% of the reference cement mortar. The fly ashes contained significant levels of chloride and sulphate and it is suggested that the performance of fly ash-cement binders could be improved by the removal or control of these chemical species.

  6. Drying Shrinkage of Cement-Based Materials Under Conditions of Constant Temperature and Varying Humidity

    Institute of Scientific and Technical Information of China (English)

    MA Bao-guo; WEN Xiao-dong; WANG Ming-yuan; YAN Jia-jia; Gao Xiao-jian

    2007-01-01

    Currently,deformations along the central axis of specimens were usually measured under fixed environmental conditions. Seldom were the effects of environmental factors on the drying-shrinkage deformation of cement-based material considered. For this paper, the drying-shrinkage deformation at different w/b ratios and different additions to mortars was investigated under different environments at a temperature of 20 ℃ and humidity ranging from 100% to 50%. The specimens were cured in water for 28 days before measurement. The results illustrate that mortar shows much less shrinkage under various drying conditions when a lower w/b ratio is adopted. With a decrease in relative humidity the speed of drying-shrinkage becomes gradually lower. The addition of silica fume reduces the drying-shrinkage of mortar under higher relative humidity, because the pore structure of mortar with silica fume becomes more refined. The addition of fly ash increases the total porosity and the volume of coarse pores in the mortar. The drying-shrinkage of mortar under different conditions increases with the addition of more of fly ash.

  7. The effect of CNTs reinforcement on thermal and electrical properties of cement-based materials

    Science.gov (United States)

    Exarchos, D. A.; Dalla, P. T.; Tragazikis, I. K.; Matikas, T. E.

    2015-03-01

    This research aims to investigate the influence of the nano-reinforcement on the thermal properties of cement mortar. Nano-modified cement mortar with carbon nanotubes (CNTs) leading to the development of innovative materials possessing multi-functionality and smartness. Such multifunctional properties include enhanced mechanical behavior, electrical and thermal conductivity, and piezo-electric characteristics. The assessment of the thermal behavior was evaluated using IR Thermography. Two different thermographic techniques are used to monitor the influence of the nano-reinforcement. To eliminate any extrinsic effects (e.g. humidity) the specimens were dried in an oven before testing. The electrical resistivity was measured with a contact test method using a custom made apparatus and applying a known D.C. voltage. This study indicate that the CNTs nano-reinforcement enhance the thermal and electrical properties and demonstrate them useful as sensors in a wide variety of applications.

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

    Science.gov (United States)

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

    2014-09-01

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

  9. Self-healing Action of Permeable Crystalline Coating on Pores and Cracks in Cement-based Materials

    Institute of Scientific and Technical Information of China (English)

    WANG Guiming; YU Jianying

    2005-01-01

    The self-healing action of a permeable crystalline coating on the porous mortar was investigated by two times impermeability test. Moreover, the self-healing mechanism of cement-based materials with the permeable crystalline coating was studied by SEM. The results indicate that the permeable crystalline coating not only seals the pores and cracks in mortar during its curing process, but also heals the permeable pathway caused by first impermeability test or cracks produced by freeze-thaw cycles. Therefore, cement-based materials can be improved by the permeable crystalline coating for the self-healing function. SEM images prove that the self-healing function is realized by generating a great quantity of non-soluble dendritic crystalline within the pores and cracks, which prevents the penetration of water and other liquids.

  10. Some aspects of cellulose ethers influence on water transport and porous structure of cement-based materials

    OpenAIRE

    Pourchez, Jérémie; Ruot, Bertrand; Debayle, Johan; Rouèche-Pourchez, Emilie; Grosseau, Philippe

    2010-01-01

    International audience; This paper evaluates and compares the impact of cellulose ethers (CE) on water transport and porous structure of cement-based materials in both fresh and hardened state. Investigations of the porous network (mercury intrusion porosimetry, apparent density, 2D and 3D observations) emphasize an air-entrained stabilisation depending on CE chemistry. We also highlight that CE chemistry leads to a gradual effect on characteristics of the water transport. The global tendenci...

  11. Multi-Scale Studies of Transport and Adsorption Phenomena of Cement-based Materials in Aqueous and Saline Environment

    OpenAIRE

    Yoon, Se Yoon

    2012-01-01

    The transport and adsorption phenomena in cement-based materials are the most important processes in the durability of concrete structures or nuclear waste containers, as they are precursors to a number of deterioration processes such as chloride-induced corrosion, sulfate attack, carbonation, etc. Despite this importance, our understanding of these processes remains limited because the pore structure and composition of concrete are complex. In addition, the range of the pore sizes, from nano...

  12. Center for Cement Composite Materials

    Science.gov (United States)

    1990-01-31

    pastes have shown that the matrix is microporous; mesopores are absent unless the material is allowed to dry out. This results in water adsorption at low...only to water. When subsequently dried a portion of3 the porosity is converted to larger mesopores . • Only about one third of the cement reacts in a...Frictional sliding, in this case was characterized by a decreasing slope in the loading curve followed by hysteresis in the unload/reloading curves

  13. Using low temperature calorimetry and moisture fixation method to study the pore structure of cement based materials

    DEFF Research Database (Denmark)

    Wu, Min

    attention was devoted to investigating important factors influencing the analysis of measured LTC data and using LTC to characterize the pore structure of cement based materials. Besides, the moisture fixation method was selected as a comparison and complementary method to the LTC. Attempts have been made...... consideration of including the model material in this investigation was to validate the applicability of the chosen methods in the context of pore size determination. In addition, data from literature were used. LTC investigations conducted in this PhD study include the ice content determination from measured...... data, the impact of sample saturation on the detected porosity, the effect of frost damage on the pore size distribution determination by LTC, the effect of preconditioning the cement paste samples on the freezing and melting behavior of the pore solution, the impact of sample crushing...

  14. Use of Different Barium Salts to Inhibit the Thaumasite Form of Sulfate Attack in Cement-based Materials

    Institute of Scientific and Technical Information of China (English)

    SU Ying; WEI Xiaochao; HUANG Jian; WANG Yingbin; HE Xingyang; WANG Xiongjue; MA Baoguo

    2016-01-01

    We investigated the effects of different barium compounds on the thaumasite form of sulphate attack (TSA) resistance of cement-based materials when they were used as admixtures in mortars. Moreover, we analyzed the inhibition mechanisms within different types of barium salts, namely BaCO3 and Ba(OH)2, on the thaumasite formation. The control cement mortar and mortars with barium salts to cement and limestone weight ratios of 0.5%, 1.0%, and 1.5% were immersed in 5% (by weight) MgSO4 solution at 5℃ to mimic TSA. Appearance, mass, and compressive strength of the mortar samples were monitored and measured to assess the general degradation extent of these samples. The products of sulphate attack were further analyzed by XRD, FTIR, and SEM, respectively. Experimental results show that different degradation extent is evident in all mortars cured in MgSO4 solution. However, barium salts can greatly inhibit such degradation. Barium in hydroxide form has better effectiveness in protection against TSA than carbonate form, which may be due to their solubility difference in alkaline cement pore solution, and the presence of these barium compounds can reduce the degree of TSA by comparison with the almost completely decomposed control samples.

  15. Improvement of Cracking-resistance and Flexural Behavior of Cement-based Materials by Addition of Rubber,Particles

    Institute of Scientific and Technical Information of China (English)

    KANG Jingfu; JIANG Yongqi

    2008-01-01

    By ring test and bend test,the improvement of waste tire rubber particles on the crack-resistance and flexural behaviors of cement-based materials were investigated.Test results show that the cracking time of the ring specimens can be retarded by the incorporation of rubber particles in the cement paste and mortar.The improvement in the crack-resistance depended on the rubber fraction.When the rubber fraction was 20%in volume,the cracking time was retarded about 15 h for the paste and 24 d for the mortar respectively.Flexural properties were evaluated based on the bend test results for both mortar and concrete containing different amount of rubber particles.Test results show that rubberized mortar and concrete specimens exhibit ductile failure and significant deformation before fracture.The ultimate deformations of both mortar and concrete specimen increase more than 2-4 times than control specimens.

  16. Investigation on the Mechanical Properties of a Cement-Based Material Containing Carbon Nanotube under Drying and Freeze-Thaw Conditions

    Directory of Open Access Journals (Sweden)

    Wei-Wen Li

    2015-12-01

    Full Text Available This paper aimed to explore the mechanical properties of a cement-based material with carbon nanotube (CNT under drying and freeze-thaw environments. Mercury Intrusion Porosimetry and Scanning Electron Microscopy were used to analyze the pore structure and microstructure of CNT/cement composite, respectively. The experimental results showed that multi-walled CNT (MWCNT could improve to different degrees the mechanical properties (compressive and flexural strengths and physical performances (shrinkage and water loss of cement-based materials under drying and freeze-thaw conditions. This paper also demonstrated that MWCNT could interconnect hydration products to enhance the performance of anti-microcracks for cement-based materials, as well as the density of materials due to CNT’s filling action.

  17. Effects of Nano-TiO2 on the Toughness and Durability of Cement-Based Material

    Directory of Open Access Journals (Sweden)

    Baoguo Ma

    2015-01-01

    Full Text Available The effects of nano-TiO2 (NT on microstructures and mechanical properties of cement mortars were studied by scanning electron microscopy (SEM, X-ray diffraction (XRD, and mercury intrusion porosimetry (MIP. Results show that 3% NT can remarkably increase the tensile/flexural strengths (i.e., the toughness is improved and promote the precipitation of AFt crystal. The flexural and tensile strengths have significant positive correlation to the formation amount of AFt. The pores of mortars can be significantly refined and shift to harmless pores by controlling the growth of CH crystal and increasing the hydration reaction rate. The durability of cement-based materials is discussed by testing their water absorption and water-vapour permeability. Results show that the addition of 3% NT can decrease the water absorption ratio by 40–65%, water absorption coefficients by more than 40%, and water-vapour permeability coefficients by 43.9%, indicating that 3% NT can effectively improve the compactness and durability of cement-based materials.

  18. Improvement, characterization and use of waste corn cob ash in cement-based materials

    Science.gov (United States)

    Suwanmaneechot, P.; Nochaiya, T.; Julphunthong, P.

    2015-12-01

    This work investigates the development of waste corn cob ash as supplementary cement replacement materials. The study focused on the effects of heat treatment on chemical composition, physical properties and engineering properties of corn cob ash. The results suggest corn cob ash that was heat treated at 600°C for 4 h shows percentage of SiO2 + Al2O3 + Fe2O3 around 72%, which can be classified as Class N calcined natural pozzolan, as prescribed by ASTM C618. The X-ray diffraction patterns indicated that the amorphous silica phase increased with increasing calcining temperatures. The water requirement, initial setting time and final setting time of specimens increased with increasing replacement percentage of raw or treated corn cob ash. The morta cubes which used 20% of treated corn cob ash replaced cement showed 103% of the 28 days compressive strength as compared to reference samples. The corn cob ash that was treated at 600°C for 4 h samples shows slightly higher effectiveness for improving the splitting tensile strength and compressive strength of concrete when compared to the untreated corn cob ash.

  19. Multi-Scale Studies of Transport and Adsorption Phenomena of Cement-based Materials in Aqueous and Saline Environment

    Science.gov (United States)

    Yoon, Se Yoon

    The transport and adsorption phenomena in cement-based materials are the most important processes in the durability of concrete structures or nuclear waste containers, as they are precursors to a number of deterioration processes such as chloride-induced corrosion, sulfate attack, carbonation, etc. Despite this importance, our understanding of these processes remains limited because the pore structure and composition of concrete are complex. In addition, the range of the pore sizes, from nanometers to millimeters, requires the multi-scale modeling of the transport and adsorption processes. Among the various environments that cement-based materials are exposed to, aqueous and saline environments represent the most common types. Therefore, this dissertation investigates the adsorption and transport phenomena of cement-based materials exposed to an aqueous and saline environment from atomic to macro-scales using different arrays of novel spectroscopic techniques and simulation methods, such as scanning transmission X-ray microscopy (STXM), X-ray absorption near edge structure (XANES), molecular dynamics (MD), and finite element method (FEM). The structure and transport of water molecules through interlayer spacing of tobermorite was investigated using MD simulations because the interlayer water of calcium silicate hydrate (C-S-H) gel influences various material properties of concrete. The adsorption processes of cementitious phases interacting with sodium and chloride ions at the nano-scale were identified using STXM and XANES measurements. A mathematical model and FEM procedure were developed to identify the effect of surface treatments at macro-scale on ionic transport phenomena of surface-treated concrete. Finally, this dissertation introduced a new material, calcined layered double hydroxide (CLDH), to prevent chloride-induced deterioration.

  20. Performance of Cement-Based Materials in Aggressive Aqueous Environments State-of-the-Art Report, RILEM TC 211 - PAE

    CERN Document Server

    Bertron, Alexandra; Belie, Nele

    2013-01-01

    Concrete and cement-based materials must operate in increasingly aggressive aqueous environments, which may be either natural or industrial.  These materials may suffer degradation in which ion addition and/or ion exchange reactions occur, leading to a breakdown of the matrix microstructure and consequent weakening.  Sometimes this degradation can be extremely rapid and serious such as in acidic environments, while in other cases degradation occurs over long periods.  Consequences of material failure are usually severe – adversely affecting the health and well-being of human communities and disturbing ecological balances. There are also large direct costs of maintaining and replacing deteriorated infrastructure and indirect costs from loss of production during maintenance work, which place a great burden on society. The focus of this book is on addressing issues concerning performance of cement-based materials in aggressive aqueous environments , by way of this State-of-the-Art Report. The book represe...

  1. Use of metakaolin to stabilize sewage sludge ash and municipal solid waste incineration fly ash in cement-based materials.

    Science.gov (United States)

    Cyr, M; Idir, R; Escadeillas, G

    2012-12-01

    The landfilling of municipal incineration residues is an expensive option for municipalities. This work evaluates an alternative way to render waste inert in cement-based materials by combining the reduction of waste content with the immobilization properties of metakaolin (MK). The functional and environmental properties of ternary and quaternary binders using cement, metakaolin, and two industrial by-products from combustion processes (MSWIFA - Municipal Solid Waste Incineration Fly Ash and SSA - Sewage Sludge Ash) were evaluated. The binders were composed of 75% cement, 22.5% metakaolin and 2.5% residue. Results on the impact of residues on the functional and environmental behavior of mortars showed that the mechanical, dimensional and leaching properties were not affected by the residues. In particular, the use of metakaolin led to a significant decrease in soluble fractions and heavy metals released from the binder matrix. The results are discussed in terms of classification of the leaching behavior, efficiency and role of metakaolin in the immobilization of heavy metals in of MSWIFA and SSA, and the pertinence of the dilution process.

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

    Science.gov (United States)

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

    2009-04-01

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

  3. Relaxation study of cement based grouting material using nuclear magnetic resonance

    Institute of Scientific and Technical Information of China (English)

    Li Xianzhong; Lin Baiquan; Zhai Cheng; Ni Guanhua; Li Ziwen

    2012-01-01

    Aiming at actual condition of poor effect of hole sealing for the reason of poor cement paste fluidity in the process of coal mine gas drainage,by adding a water reducing agent,cement paste for hole sealing was produced.The changes of initial distribution,weighted average values and total relaxation signal intensity of transverse relaxation time (T2) of water in pure cement paste and water reducing agent added cement paste were studied with low field proton nuclear magnetic resonance (NMR).The results show that there are four peaks in T2 distribution curves of cement paste:the first peak is related to the bound water in flocculation,the second and the third peaks are related to the water in flocculation,water reducing agent makes it extending towards the long relaxation time,increasing its liquidity,and the fourth peak is related to the free water.By using weighted average values of T2 and total relaxation signal intensity,hydration process of cement pastes could be roughly divided into four stages:the initial period,reaction period,accelerated period and steady period.By analyzing the periods,it makes sure that the grouting process should be completed in the reaction period in the site,and the drainage process should be started in the steady period.The results have great guiding significance to the hole sealing and methane drainage.

  4. Relaxation study of cement based grouting material using nuclear magnetic resonance

    Institute of Scientific and Technical Information of China (English)

    Li; Xianzhong; Lin; Baiquan; Zhai; Cheng; Ni; Guanhua; Li; Ziwen

    2012-01-01

    Aiming at actual condition of poor effect of hole sealing for the reason of poor cement paste fluidity in the process of coal mine gas drainage,by adding a water reducing agent,cement paste for hole sealing was produced.The changes of initial distribution,weighted average values and total relaxation signal intensity of transverse relaxation time(T 2) of water in pure cement paste and water reducing agent added cement paste were studied with low field proton nuclear magnetic resonance(NMR).The results show that there are four peaks in T2 distribution curves of cement paste:the first peak is related to the bound water in flocculation,the second and the third peaks are related to the water in flocculation,water reducing agent makes it extending towards the long relaxation time,increasing its liquidity,and the fourth peak is related to the free water.By using weighted average values of T2 and total relaxation signal intensity,hydration process of cement pastes could be roughly divided into four stages:the initial period,reaction period,accelerated period and steady period.By analyzing the periods,it makes sure that the grouting process should be completed in the reaction period in the site,and the drainage process should be started in the steady period.The results have great guiding significance to the hole sealing and methane drainage.

  5. Numerical Analysis and Optimization on Piezoelectric Properties of 0–3 Type Piezoelectric Cement-Based Materials with Interdigitated Electrodes

    Directory of Open Access Journals (Sweden)

    Jianlin Luo

    2017-03-01

    Full Text Available The health conditions of complicated concrete structures require intrinsic cement-based sensors with a fast sensing response and high accuracy. In this paper, static, modal, harmonic, and transient dynamic analyses for the 0–3 type piezoelectric cement-based material with interdigitated electrodes (IEPCM wafer were investigated using the ANSYS finite element numerical approach. Optimal design of the IEPCM was further implemented with electrode distance (P, electrode width (W, and wafer density (H as the main parameters. Analysis results show that the maximum stress and strain in the x-polarization direction of the IEPCM are 2.6 and 3.19 times higher than that in the y-direction, respectively; there exists no repetition frequency phenomenon for the IEPCM. These indicate 0–3 type IEPCM possesses good orthotropic features, and lateral driving capacity notwithstanding, a hysteresis effect exists. Allowing for the wafer width (Wp of 1 mm, the optimal design of the IEPCM wafer arrives at the best physical values of H, W and P are 6.2, 0.73 and 1.02 mm respectively, whereas the corresponding optimal volume is 10.9 mm3.

  6. Evaluation of the Katz-Thompson model for estimating the water permeability of cement-based materials from mercury intrusion porosimetry data

    Energy Technology Data Exchange (ETDEWEB)

    El-Dieb, A.S.; Hooton, R.D. (Univ. of Toronto, Ontario (Canada). Dept. of Civil Engineering)

    1994-01-01

    The permeability of concrete is becoming a focal characteristic with regard to the durability and performance of cement-based materials, pastes, mortars and concretes. Since it is mainly affected by the microstructure of the porous media, many models and theories have been developed relating the permeability of porous media to their microstructural parameters. One which proved to be useful in predicting the permeability of sedimentary rock, from mercury intrusion porosimetry data, is the Katz-Thompson theory. A review of this theory and its assumptions is presented, and its applicability to cementitious materials is investigated using two sets of data of various hardened cement pastes and concretes. Also, the major differences between cement-based materials and sedimentary rock from the microstructural point of view is reported.

  7. Ductile Cement-Based Composites with Wood Fibres - material design and experimental approach

    NARCIS (Netherlands)

    Sierra-Beltran, M.G.

    2011-01-01

    In order to turn a brittle cement matrix into a ductile composite different types of man-made fibres such as steel, glass and polyvinyl alcohol are currently used as reinforcement, as well as some natural fibres. Compared to synthetic fibres, natural fibres are more easily available worldwide and th

  8. Visualization and quantification of water movement in porous cement-based materials by real time thermal neutron radiography:Theoretical analysis and experimental study

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Water movement in porous cement-based materials is of great importance when studying their deterioration processes and durability.Many traditional methods based on mass changes,electricity or nuclear magnetic resonances are available for studying water transport in cement-based materials.In this research,an advanced technique i.e.thermal neutron radiography was utilized to achieve visualization and quantification of time dependent water movement including water penetration and moisture vapor in porous cement-based materials through theoretical analysis and experimental study.Because thermal neutrons ex-perience a strong attenuation by hydrogen,neutron radiography exhibits high sensitivity to small amounts of water.A neutron transmission analysis for quantitative evaluation of raw radiographic measurements was developed and optimized based on point scattered functions(PScF).The determinations of the real time and space dependent water penetration into uncracked and cracked mortar samples,as well as the drying process have been presented in this paper.It is illustrated that thermal neutron radiography can be a useful research tool for visualization and quantification of water movement in porous building materials.The obtained results will help us to better understand deteriorating processes of cement-based materials and to find ways to improve their durability.

  9. Phosphate based oil well cements

    Science.gov (United States)

    Natarajan, Ramkumar

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

  10. Effects of the Component and Fiber Gradient Distributions on the Strength of Cement-based Composite Materials

    Institute of Scientific and Technical Information of China (English)

    YANG Jiu-jun; HAI Ran; DONG Yan-ling; WU Ke-ru

    2003-01-01

    The effects of the component gradient distribution at interface and the fiber gradient distribution on the strength of cement-based materials were studied.The results show that the flexural strength and compressive strength of the mortar and concrete with interface component and fiber gradient distributions are obviously improved.The strengthes of the fiber gradient distributed mortar and concrete (FGDM/C) are higher than those of fiber homogeneously distributed mortar and concrete (FHDM/C).To obtain the same strength,therefore,a smaller fiber volume content in FGDM/C is needed than that in FHDM/C.The results also show that the component gradient distribution of the concrete can be obtained by means of multi-layer vibrating formation.

  11. Leaching of metals on stabilization of metal sludge using cement based materials

    Institute of Scientific and Technical Information of China (English)

    Carmalin Sophia A; K. Swaminathan

    2005-01-01

    Toxicity characteristic leaching procedure(TCLP) of zinc plating sludge was carried out to assess the leaching potential of the sludge and the leachates were analyzed for heavy metals. The concentration of zinc, chromium, and lead in the leachate were 371.5mg/L, 1.95 mg/L and 1.99 mg/L respectively. Solidification of zinc sludge was carried out using four different binder systems consisting of cement mortar, fly ash, clay and lime and cured for 28 d. The ratio of sludge added varied from 60% to 80% by volume. The solidified products were tested for metal fixing efficiency and physical strength. It was observed that the volume of sludge added that resulted in maximum metal stabilization was 60% for all the combinations, above which the metal fixation efficiency decreased resulting in high values of zinc in the leachate. Addition of 5% sodium silicate enhanced the chemical fixation of metals in all the binder systems. Among the four fixing agents studied, mixture of fly ash: lime, and cement mortar: lime stabilized zinc and other metals in the sludge effectively than other combinations. Addition of lime increased the stabilization of zinc whereas cement mortar increased the strength of the solidified product.

  12. 磷石膏基胶结材固结磷尾矿性能及浸出特征%Properties and leaching characteristics of cemented phosphate tailings backfill with phosphogypsum-based cementation material

    Institute of Scientific and Technical Information of China (English)

    黄绪泉; 赵小蓉; 唐次来; 冯思源; 杜奕锦; 陈伯宇

    2016-01-01

    以磷石膏基材料代替水泥作为磷尾矿充填胶结材,研究了磷尾矿固结浆体和硬化体性能、浸出液污染特性和固结机理.结果表明,在同样条件下,磷石膏基材料固结磷尾矿浆体比水泥泌水量要小、浆体流动性能更优;磷石膏基材料胶结磷尾矿硬化体除3d抗压强度略低外,其他龄期的强度是水泥的1.21~1.95倍.3d之后,磷石膏基材料和水泥胶结尾矿硬化体浸出液总磷含量基本相近,但pH明显远低于水泥,总磷也低于污水综合排放标准限值,对环境危害低.硬化体SEM和XRD分析发现,磷石膏基材料水化生成的水化硅酸钙凝胶、针状钙矾石晶体和磷尾矿中白云石、含磷矿物生成的透钙磷石等,是整个磷尾矿固结硬化体具有较高强度、较低总磷含量和pH值主要原因.该研究表明,磷石膏基材料固化磷尾矿比水泥更有应用前景.%Cementation mechanism and properties,which include the cementation slurry and a hardened specimen,along with the contamination properties of liquid leaching of phosphate tailings cementation with a phosphogypsum-based material (PM),as opposed to cement,were investigated in this study.The results showed that the bleeding quantity of a phosphate tailing cementation slurry with PM was smaller,and that the slurry fluidity with PM was better than that with cement under the same conditions.The compressive strength of the phosphate tailing hardened specimen with PM with different hydration age was 1.21 to 1.95 times higher than that with cement,except for a 3 day hydration.After a 3 day hydration period,the total phosphorus in the liquid leaching of hardened specimens with PM and cement was similar,but the pH with PM was far lower than that with cement.The total phosphorus in liquid leaching with PM was below the integrated wastewater discharge standard of China,which implied that the liquid leaching of hardened specimens with PM was safe to the environment.SEM and XRD

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

    Directory of Open Access Journals (Sweden)

    Shengli Li

    2016-01-01

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

  14. Evaluation of the leachability of heavy metals from cement-based materials.

    Science.gov (United States)

    Dell'Orso, Marcello; Mangialardi, Teresa; Paolini, Antonio Evangelista; Piga, Luigi

    2012-08-15

    A new leaching test on comminuted (0.125-2.0mm gradation) cementitious matrices, designated as Modified-Pore Water (M-PW) test, was developed to evaluate the effect of varying leachate pH (4-12.8) and/or liquid-to-solid, L/S, ratio (0.6-50 dm(3)/kg) on the availability factor, F(AV), of heavy metals. The M-PW test was applied to leaching of lead and zinc ions from ground Portland cement mortar incorporating Municipal Solid Waste Incinerator (MSWI) fly ash. Correlation of M-PW test results (F(AV)-L/S data) allowed the determination of the pore-liquid availability factor, F(AVP), at different leachate pHs. These F(AVP) values were utilized, in conjunction with a kinetic pseudo-diffusional model, to evaluate the leaching behavior of monolithic mortar specimens subjected to dynamic leaching tests (constant leachant pH 4 or 6).A good agreement was found between the effective diffusion coefficients, D(e), of lead and zinc ions calculated by such a methodological approach and those obtained from recognized microstructural models. In contrast, no satisfactory agreement was found when these D(e) values were compared with the ones calculated from the results of other availability tests on granular solid samples (NEN 7341 and AAT tests).

  15. Self-healing of drying shrinkage cracks in cement-based materials incorporating reactive MgO

    Science.gov (United States)

    Qureshi, T. S.; Al-Tabbaa, A.

    2016-08-01

    Excessive drying shrinkage is one of the major issues of concern for longevity and reduced strength performance of concrete structures. It can cause the formation of cracks in the concrete. This research aims to improve the autogenous self-healing capacity of traditional Portland cement (PC) systems, adding expansive minerals such as reactive magnesium oxide (MgO) in terms of drying shrinkage crack healing. Two different reactive grades (high ‘N50’and moderately high ‘92-200’) of MgO were added with PC. Cracks were induced in the samples with restraining end prisms through natural drying shrinkage over 28 days after casting. Samples were then cured under water for 28 and 56 days, and self-healing capacity was investigated in terms of mechanical strength recovery, crack sealing efficiency and improvement in durability. Finally, microstructures of the healing materials were investigated using FT-IR, XRD, and SEM-EDX. Overall N50 mixes show higher expansion and drying shrinkage compared to 92-200 mixes. Autogenous self-healing performance of the MgO containing samples were much higher compared to control (only PC) mixes. Cracks up to 500 μm were sealed in most MgO containing samples after 28 days. In the microstructural investigations, highly expansive Mg-rich hydro-carbonate bridges were found along with traditional calcium-based, self-healing compounds (calcite, portlandite, calcium silicate hydrates and ettringite).

  16. Inorganic powder encapsulated in brittle polymer particles for self-healing cement-based materials

    NARCIS (Netherlands)

    Dong, H.; Huang, H.; Ye, G.

    2013-01-01

    Many types of healing agents have been investigated. These agents are processed in different ways, such as adhesive polymer in capsules or hollow fibre glasses, bacteria in porous aggregates and geo-materials directly incorporated in the cementbased materials. In this study, sodium silicate powder i

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

    Science.gov (United States)

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

    2016-01-01

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

  18. 水泥基灌浆材料流动性能的研究%Study on the flow property of cement based grouting material

    Institute of Scientific and Technical Information of China (English)

    高汉青; 于大第; 杨晓光; 王炜; 潘美; 郑旗

    2014-01-01

    Two test methods were introduced for the flow property testing of cement based grouting material ,truncated cone method and flow cone method.Experiments were carried out to compare the flow performances of same cement based grouting material by the two dif-ferent test methods,and the result showed that the flow property of cement based grouting material with high fluidity could not be fully characterized only by the truncated method.Cement based material with excellent flow performance was prepared by using the self-made anti-settling agent,and it could meet the requirements of both GB/T 50448-2008 and ASTM-C939-2012.%介绍了国内标准与ASTM标准测试水泥基灌浆材料流动性能所采用的两种方法:截锥圆模法和流锥法,试验比较了水泥基灌浆材料在两种测试方法下的性能表现差异,结果表明国内标准仅采用截锥圆模法无法全面表征大流动度水泥基灌浆材料的流动特性。采用自制防沉剂,配制了同时满足GB/T 50448-2008和ASTM C939-2012要求的具有高流动性能的水泥基灌浆材料。

  19. USE OF CRUMB RUBBER TO IMPROVE THERMAL EFFICIENCY OF CEMENT-BASED MATERIALS

    Directory of Open Access Journals (Sweden)

    Ashraf Fadiel

    2014-01-01

    Full Text Available Motivated by the tremendous trend toward green environment and to reduce the effect of scrap tires on the environment and human health, this research is an attempt to find a practical and environmentally sound solution of the problem of scrap tires by developing a light weight with low thermal conductivity composite construction materials using waste tires. A few literatures may be found about the effect of crumb rubber on thermal conductivity of mortar. Thus, in this research project, an experimental program was established to investigate the effect of the amount and size of crumb rubber (rubber obtained from recycling scrap tires on the thermal properties of mortar. Four levels of crumb rubber addition: 10, 20, 30 and 40% and three sizes of crumb rubber (#30, #10_20 and a combination of both sizes were considered to make twelve different mixtures of the rubberized mortar. Specially designed and constructed heat transfer measurement device was used to measure thermal conductivity of the specimens. Results were used to determine the optimal amount of crumb rubber that gives the least thermal conductivity, which directly related to the improvement in thermal resistance of concrete mixtures. It was found that the size and the amount of crumb rubber had an effect on thermal properties of the specimens investigated. The thermal conductivity of rubberized mortar was decreased by 28% when crumb rubber #10_20 was used. It was also found that #10_20 crumb rubber had more effect on the thermal conductivity reduction than #30 crumb rubbers. An empirical equation is proposed to predict thermal conductivity of rubberized mortar.

  20. Interactions between chloride and cement-paste materials.

    Science.gov (United States)

    Barberon, Fabien; Baroghel-Bouny, Véronique; Zanni, Hélène; Bresson, Bruno; d'Espinose de la Caillerie, Jean-Baptiste; Malosse, Lucie; Gan, Zehong

    2005-02-01

    The durability of cement-based materials with respect to exterior aggressions is one of the current priorities in civil engineering. Depending on their use, the cement-based materials can be exposed to different types of aggressive environments. For instance, damages to concrete structures in contact with a saline environment (sea water on bridges, deicing salts on roads, etc.) are of utmost importance. Upon exposure to saline water, Cl- ions penetrate into the structures and subsequently lead to reinforcement corrosion. Chloride attack is often combined with other aggressive influences such as temperature (e.g., freezing) or the ingress of other ions (e.g., sulfates in sea water). We therefore aim to explore the effect of sodium chloride (NaCl) on the structural chemistry of cement paste. Existing studies about reinforcement corrosion by chloride have focused on the penetration of Cl- ions and the comparison between "free" ions (water-soluble ions) and bound ones. However, little is known about the fixation mechanisms, the localization of Cl in the cement matrix and the structural interaction between Cl and the silicate and aluminate hydrate phases present in cement paste. We present here results of a multinuclear nuclear magnetic resonance study on the fixation of chloride in the hydration products and the characterization of new phases potentially appearing due to chloride ingress.

  1. 水泥基材料表面渗透防护试验研究%Experimental Study on Cement-based Material Surface Permeability Protection

    Institute of Scientific and Technical Information of China (English)

    章岩; 王起才; 张忠元; 李韶瑜; 彭峰

    2014-01-01

    Harmful ions in environment can invade cement-based materials by the carrier of water, so improving the water resistance of the surface can improve anti-corrosion properties of harmful ions.Penetration protective material,which is different from the traditional means of additional thick protective surface coating,penetrates the surface of the substrate materials and forms water-repellent protective layer on the substrate surface so as to achieve the purpose of improving its anti-erosion ability to water containing harmful ion.The research results show that the surface of the cement-based materials achieves "super water-repellent"effect and the surface water absorp-tion of cement mortar test block is reduced 28.7 times after processed by the silicone surface pro-tection materials prepared.%水是环境中有害离子对水泥基材料构成侵害的载体,提高抗水性能就可提高抗有害离子侵蚀性能,渗透防护材料区别于在水泥基材料表面附加厚质防护涂层的传统手段,通过基材表面渗透,可在基材表层形成拒水防护层,以达到提高其抗水载有害离子侵蚀的能力的目的.研究结果表明,经研制出的有机硅类表面防护材料处理,可使水泥基材料的表面实现“超防水”效果,经防护处理后的水泥砂浆试块表面吸水率可降低28.7倍.

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

    Science.gov (United States)

    Nochaiya, Thanongsak; Chaipanich, Arnon

    2011-01-01

    The porosity and microstructure of a Portland cement-multi-walled carbon nanotube composite were investigated. Multi-walled carbon nanotubes (CNTs), up to 1 wt.% of cement, synthesized by infusion chemical vapor deposition, and Portland cement type I (PC) were used to produce pastes with a water to cement ratio of 0.5. Mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) were used to characterize Portland cement-CNTs systems. MIP analysis of the results indicates that total porosity of the mixes with CNTs was found to decrease with increasing CNTs content. Moreover, an important effect of additional CNTs was a reduction in the number of mesopores, while SEM technique showed dispersion of CNTs between the hydration phases of Portland cement pastes.

  3. Form and Mechanism of Sulfate Attack on Cement-based Material Made of Limestone Powder at Low Water-binder Ratio under Low Temperature Conditions

    Institute of Scientific and Technical Information of China (English)

    LIU Juanhong; SONG Shaomin; XU Guoqiang; XU Weiguo

    2012-01-01

    The development of strength and the form of attack of cement-based material made of limestone powder at low water-binder ratio under low-temperature sulfate environment were studied.The results indicate that when water-binder ratio is lower than 0.40,the cement-based material with limestone powder has insignificant change in appearance after being soaked in 10% magnesium sulfate solution at low temperature for 120 d,and has significant change in appearance after being soaked at the age of 200 d.Expansion damage and exfoliation occur on the surface of concrete test cube at different levels.When limestone powder accounts for about 28 percent of cementitious material,with the decrease of water-binder ratio,the compressive strength loss has gradually decreased after the material is soaked in the magnesium sulfate solution at low temperature at the age of 200 d.After the specimen with the water-binder ratio of less than 0.4 and the limestone powder volume of greater than 20% is soaked in 10% magnesium sulfate solution at low temperature at the age of 200 d,gypsum attack-led destruction is caused to the concrete test cube,without thaumasite sulfate attack.

  4. The mineralogy and chemistry of cement and cement raw materials In the united arab emirates

    OpenAIRE

    Nasir, Sobhi J. [صبحي جابر نصر; El Etr, H.

    1996-01-01

    The raw materials, clinkers and cements from different cement factories in the United Arab Emirates have been investigated using polarizing microscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), and chemical analyses. The chemical and mineralogical analyses indicate that the local raw materials are suitable for cement industry. Geological review shows that there is a good potential for industrial-grade local occurrences of limestone, marl, gypsum and iron oxide, that may be ...

  5. Inference of the phase-to-mechanical property link via coupled X-ray spectrometry and indentation analysis: Application to cement-based materials

    Energy Technology Data Exchange (ETDEWEB)

    Krakowiak, Konrad J.; Wilson, William [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307 (United States); James, Simon [Schlumberger Riboud Product Center, 1 Rue Henri Becquerel, Clamart 92140 (France); Musso, Simone [Schlumberger-Doll Research Center, 1 Hampshire St., Cambridge, MA 02139-1578 (United States); Ulm, Franz-Josef, E-mail: ulm@mit.edu [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307 (United States)

    2015-01-15

    A novel approach for the chemo-mechanical characterization of cement-based materials is presented, which combines the classical grid indentation technique with elemental mapping by scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS). It is illustrated through application to an oil-well cement system with siliceous filler. The characteristic X-rays of major elements (silicon, calcium and aluminum) are measured over the indentation region and mapped back on the indentation points. Measured intensities together with indentation hardness and modulus are considered in a clustering analysis within the framework of Finite Mixture Models with Gaussian component density function. The method is able to successfully isolate the calcium-silica-hydrate gel at the indentation scale from its mixtures with other products of cement hydration and anhydrous phases; thus providing a convenient means to link mechanical response to the calcium-to-silicon ratio quantified independently via X-ray wavelength dispersive spectroscopy. A discussion of uncertainty quantification of the estimated chemo-mechanical properties and phase volume fractions, as well as the effect of chemical observables on phase assessment is also included.

  6. Comparative evaluation of shear bond strength and microleakage of tricalcium silicate-based restorative material and radioopaque posterior glass ionomer restorative cement in primary and permanent teeth: An in vitro study

    Directory of Open Access Journals (Sweden)

    Vignesh Guptha Raju

    2014-01-01

    Full Text Available Background: Restoration of carious primary molars is still a major concern while treating the young children that too in deep carious lesion which extends below the cemento-enamel junction (CEJ where pulp protection and achieving adequate marginal seal are very important to prevent secondary caries. The needs were met with the development of new materials. One such of new bioactive material is tricalcium silicate-based restorative material (Biodentine, recommended for restoring deep lesions. Aim: To evaluate and compare shear bond strength and microleakage of tricalcium silicate-based restorative material (Biodentine and glass ionomer cement (Fuji IX GP in primary and permanent teeth. Materials and Methods: Occlusal surface of crowns were ground flat. PVC molds were stabilized over flat dentin surface and filled with tricalcium silicate-based restorative material (Biodentine/glass ionomer cement (Fuji IX GP according to group ascertained. Shear bond strength was evaluated using universal testing machine (INSTRON. Standardized Class II cavities were prepared on both primary and permanent teeth, and then restored with tricalcium silicate-based restorative material (Biodentine/glass ionomer cement (Fuji IX GP according to group ascertained, over which composite resin material was restored using an open sandwich technique. Microleakage was assessed using dye penetration. Microleakage was examined using a stereomicroscope. Results: Results showed that glass ionomer cement (Fuji IX GP exhibited better shear bond strength than tricalcium silicate-based restorative material (Biodentine. Mean microleakage score for glass ionomer cement (Fuji IX GP in permanent teeth was 1.52 and for primary teeth was 1.56. The mean microleakage for tricalcium silicate-based restorative material (Biodentine in permanent teeth was 0.76 and for primary teeth was 0.60. Glass ionomer cement (Fuji IX GP exhibited more microleakage than tricalcium silicate-based restorative

  7. Assessing the potential of ToF-SIMS as a complementary approach to investigate cement-based materials — Applications related to alkali–silica reaction

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, Laetitia, E-mail: laetitia.bernard@empa.ch [Laboratory for Nanoscale Materials Science, Empa, Swiss Federal Laboratories for Material Science and Technology, Ueberlandstr. 129, 8600 Duebendorf (Switzerland); Leemann, Andreas [Laboratory for Concrete/Construction Chemistry, Empa, Swiss Federal Laboratories for Material Science and Technology, Ueberlandstr. 129, 8600 Duebendorf (Switzerland)

    2015-02-15

    In this study, the potential of time-of-flight secondary ion mass spectrometry (ToF-SIMS) for the application in cement-based materials is assessed in combination and comparison with scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). Mortar, concrete and samples from model systems providing products formed by the alkali–silica reaction (ASR) were studied. ToF-SIMS provides qualitative data on alkalis in cases where EDX reaches its limits in regard to detectable concentration, lateral resolution and atomic number of the elements. Due to its high in-depth resolution of a few atomic monolayers, thin layers of reaction products can be detected on the surfaces and chemically analyzed with ToF-SIMS. Additionally, it delivers information on the molecular conformation within the ASR product, its hydrogen content and its isotope ratios, information not provided by EDX. Provided the samples are carefully prepared, ToF-SIMS opens up new possibilities in the analysis of cement-based materials.

  8. Physical properties and cytotoxicity comparison of experimental gypsum-based biomaterials with two current dental cement materials on L929 fibroblast cells

    Directory of Open Access Journals (Sweden)

    Nafsiyah Mahshim

    2013-01-01

    Full Text Available Aim: To evaluate physical properties and cytotoxicity of pure gypsum-based (pure-GYP and experimental gypsum-based biomaterials mixed with polyacrylic acid (Gyp-PA. The results were compared with calcium hydroxide (CH and glass ionomer cement (GIC for application as base/liner materials. Materials and Methods: Vicat′s needle was used to measure the setting time and solubility (% was determined by percentage of weight loss of the materials following immersion in distilled water. For cytotoxicity test, eluates of different concentrations of materials were obtained and pipetted onto L-929 mouse fibroblast cultures and incubated for 3 days. Cellular viability was assessed using Dimethylthiazol diphenyltetrazolium bromide test to determine the cytotoxicity level. Statistical significance was determined by one-way analysis of variance followed by post hoc test ( P Gyp-PA > CH = GIC. The pure-Gyp was found as the least cytotoxic materials at different concentrations. At 100 mg/mL dilutions of materials in growth medium highest cytotoxicity was observed with CH group. Conclusion: Cytotoxic effect was not observed with pure-Gyp; application of this novel biomaterial on deeper dentin/an exposed pulp and possibility of gradual replacement of this biodegradable material by dentin like structure would be highly promising.

  9. Modeling and Optimization of Cement Raw Materials Blending Process

    Directory of Open Access Journals (Sweden)

    Xianhong Li

    2012-01-01

    Full Text Available This paper focuses on modelling and solving the ingredient ratio optimization problem in cement raw material blending process. A general nonlinear time-varying (G-NLTV model is established for cement raw material blending process via considering chemical composition, feed flow fluctuation, and various craft and production constraints. Different objective functions are presented to acquire optimal ingredient ratios under various production requirements. The ingredient ratio optimization problem is transformed into discrete-time single objective or multiple objectives rolling nonlinear constraint optimization problem. A framework of grid interior point method is presented to solve the rolling nonlinear constraint optimization problem. Based on MATLAB-GUI platform, the corresponding ingredient ratio software is devised to obtain optimal ingredient ratio. Finally, several numerical examples are presented to study and solve ingredient ratio optimization problems.

  10. Porosity prediction of calcium phosphate cements based on chemical composition.

    Science.gov (United States)

    Öhman, Caroline; Unosson, Johanna; Carlsson, Elin; Ginebra, Maria Pau; Persson, Cecilia; Engqvist, Håkan

    2015-07-01

    The porosity of calcium phosphate cements has an impact on several important parameters, such as strength, resorbability and bioactivity. A model to predict the porosity for biomedical cements would hence be a useful tool. At the moment such a model only exists for Portland cements. The aim of this study was to develop and validate a first porosity prediction model for calcium phosphate cements. On the basis of chemical reaction, molar weight and density of components, a volume-based model was developed and validated using calcium phosphate cement as model material. 60 mol% β-tricalcium phosphate and 40 mol% monocalcium phosphate monohydrate were mixed with deionized water, at different liquid-to-powder ratios. Samples were set for 24 h at 37°C and 100% relative humidity. Thereafter, samples were dried either under vacuum at room temperature for 24 h or in air at 37 °C for 7 days. Porosity and phase composition were determined. It was found that the two drying protocols led to the formation of brushite and monetite, respectively. The model was found to predict well the experimental values and also data reported in the literature for apatite cements, as deduced from the small absolute average residual errors (brushite, monetite and apatite cements. The model gives a good estimate of the final porosity and has the potential to be used as a porosity prediction tool in the biomedical cement field.

  11. PMMA-based composite materials with reactive ceramic fillers: part III: radiopacifying particle-reinforced bone cements.

    Science.gov (United States)

    Abboud, M; Vol, S; Duguet, E; Fontanille, M

    2000-05-01

    New acrylic bone cements were prepared from alumina particles previously treated by 3-(trimethoxysilyl)propylmethacrylate (gamma-MPS), able to act both as radiopacifying and reinforcing agents. The present study deals with the handling characteristics and the compressive behavior of such cements. The influence of the particles morphology, their surface-modification by gamma-MPS bonding agent, their concentration in the cement, the powder-to-liquid ratio and the benzoyl peroxide concentration are reported. The role of grafted gamma-MPS molecules as coupling agent was confirmed. For several formulations, compressive strength and modulus reached 150 MPa and 3400 MPa respectively. Limitations in the use of such formulations are also comprehensively discussed.

  12. 磷酸镁水泥基材料耐久性研究进展%Research Progresses on Durability of Magnesium Phosphate Cement Based Materials

    Institute of Scientific and Technical Information of China (English)

    常远; 史才军; 杨楠; 杨建明

    2014-01-01

    Magnesium phosphate cement based materials possess many advantages including small dry shrinkage,excellent re-sistance to abrasion and deicer-scaling or freezing and thawing,good resistance to steel corrosion and wetting-drying cycle and so on.It is suggested that dry shrinkage of magnesium phosphate cement based materials is greatly effected by water to binder ratio,surface activity of magnesium oxide,phosphate to magnesia ratio,retarder and addition of fly ash.Excellent resistance to deicer-scaling or freezing and thawing owe to small water to binder ratio and lots of enclosed pores inside.These enclosed pores may be caused by creation of carbon dioxide gas or evaporation of free water for hydration heat evolution.Magnesium phosphate cement based materials has weak resistance to water or acid and alkali corrosion which may be improved by improve-ment of retarder,increasing fineness of phosphate prolonging pre-curing time.%磷酸镁水泥基材料具有干缩小、耐磨性好、抗冻性和抗盐冻剥蚀性能优良、防钢筋锈蚀性能和抗干湿循环性能优良等特点。氧化镁活性、磷镁比、缓凝剂、水胶比以及粉煤灰掺量对磷酸镁水泥基材料干燥收缩有显著影响。水灰比低及基体内部存在大量均匀封闭气孔是磷酸镁水泥基材料基体抗冻性优良的主要原因,大量封闭气孔可能是基体内部发生化学反应生成二氧化碳气体造成或是由于水化放热过程中自由水蒸发受阻后经水化产物填充形成的。磷酸镁水泥基材料耐水性能和耐酸碱腐蚀性较差,但耐水性可通过改善缓凝剂、增大磷酸盐细度、增加预养护时间来改善。

  13. A non-destructive test method to monitor corrosion products and corrosion-induced cracking in reinforced cement based materials

    DEFF Research Database (Denmark)

    Michel, Alexander; Pease, Bradley Justin; Peterova, Adela;

    2011-01-01

    ) was conducted to describe the impact of water-to-cement ratio and corrosion current density (i.e., corrosion rate) on the reinforcement corrosion process. Focus was placed, in particular on the determination of the corrosion accommodating region (CAR) and time to corrosion-induced cracking. Experimental results...

  14. Sulfur Release from Cement Raw Materials during Solid Fuel Combustion

    DEFF Research Database (Denmark)

    Nielsen, Anders Rooma; Larsen, Morten B.; Glarborg, Peter

    2011-01-01

    During combustion of solid fuels in the material inlet end of cement rotary kilns, local reducing conditions can occur and cause decomposition of sulfates from cement raw materials. Decomposition of sulfates is problematic because it increases the gas-phase SO2 concentration, which may cause...... deposit formation in the kiln system. SO2 release from cement raw materials during combustion of solid fuels has been studied experimentally in a high temperature rotary drum. The fuels were tire rubber, pine wood, petcoke, sewage sludge, and polypropylene. The SO2 release from the raw materials...

  15. Progress in development of coated indexable cemented carbide inserts for machining of iron based work piece materials

    Science.gov (United States)

    Czettl, C.; Pohler, M.

    2016-03-01

    Increasing demands on material properties of iron based work piece materials, e.g. for the turbine industry, complicate the machining process and reduce the lifetime of the cutting tools. Therefore, improved tool solutions, adapted to the requirements of the desired application have to be developed. Especially, the interplay of macro- and micro geometry, substrate material, coating and post treatment processes is crucial for the durability of modern high performance tool solutions. Improved and novel analytical methods allow a detailed understanding of material properties responsible for the wear behaviour of the tools. Those support the knowledge based development of tailored cutting materials for selected applications. One important factor for such a solution is the proper choice of coating material, which can be synthesized by physical or chemical vapor deposition techniques. Within this work an overview of state-of-the-art coated carbide grades is presented and application examples are shown to demonstrate their high efficiency. Machining processes for a material range from cast iron, low carbon steels to high alloyed steels are covered.

  16. Smart Behavior of Carbon Fiber Reinforced Cement-based Composite

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The electrical characteristics of cement-based material can be remarkably improved by the addition of short carbon fibers.Carbon fiber reinforced cement composite (CFRC) is an intrinsically smart material that can sense not only the stress andstrain, but also the temperature. In this paper, variations of electrical resistivity with external applied load, and relationof thermoelectric force and temperature were investigated. Test results indicated that the electrical signal is related to theincrease in the material volume resistivity during crack generation or propagation and the decrease in the resistivity duringcrack closure. Moreover, it was found that the fiber addition increased the linearity and reversibility of the Seebeck effect inthe cement-based materials. The change of electrical characteristics reflects large amount of information of inner damage andtemperature differential of composite, which can be used for stress-strain or thermal self-monitoring by embedding it in theconcrete structures.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mejia de Gutierrez, R.

    2003-07-01

    Failure of concrete after a period of years, less than the life expected for which it was designed, may be caused by the environment to which it has been exposed or by a variety of internal causes. The incorporation of supplementary materials has at the Portland cement the purpose of improving the concrete microstructure and also of influence the resistance of concrete to environmental attacks. Different mineral by-products as ground granulated blast furnaces slag (GGBS), silica fume (SF), meta kaolin (MK), fly ash (FA) and other products have been used as supplementary cementing materials. This paper is about the behavior of concrete in the presence of mineral additions. Compared to Portland cements, blended cements show lower heat of hydration, lower permeability, greater resistance to sulphates and sea water. These blended cements find the best application when requirements of durability are regarded as a priority specially on high performance concrete: (Author) 11 refs.

  18. Structure and Property Characterization of Oyster Shell Cementing Material

    Institute of Scientific and Technical Information of China (English)

    钟彬杨; 周强; 单昌锋; 于岩

    2012-01-01

    Oyster shell powder was used as the admixture of ordinary portland cement.The effects of different addition amounts and grinding ways on the strength and stability of cement mortar were discussed and proper addition amount of oyster shell powder was determined.The structure and property changes of cementing samples with different oyster shell powder contents were tested by XRD and SEM means.The results revealed that compressive and rupture strengths of the sample with 10% oyster shell powder was close to those of the original one without addition.Stability experiment showed that the sample prepared by pat method had smooth surface without crack and significant expansion or shrinkage after pre-curing and boiling,which indicated that cementing material dosed with oyster shell powder had fine stability.XRD and SEM observation showed that oyster shell independently exists in the cementing material.

  19. Minimally invasive maxillofacial vertical bone augmentation using brushite based cements.

    Science.gov (United States)

    Tamimi, Faleh; Torres, Jesus; Lopez-Cabarcos, Enrique; Bassett, David C; Habibovic, Pamela; Luceron, Elena; Barralet, Jake E

    2009-01-01

    An ideal material for maxillofacial vertical bone augmentation procedures should not only be osteoconductive, biocompatible and mechanically strong, but should also be applied using minimally invasive procedures and remain stable with respect to the original bone surfaces. This way, implant exposure and infection might be reduced and good mechanical stability may be achieved. Calcium phosphate cements are proven biocompatible and osteoconductive materials that can be injected using minimally invasive procedures. Among these cements, brushite based cements have the added advantage of being biodegradable in vivo. Therefore, this material has the potential for use in the aforementioned procedures. An in vivo study was performed in rabbits to evaluate the potential use of brushite cements in minimally invasive maxillofacial vertical bone augmentation procedures. In this study, we injected self-setting brushite cements on the subperiosteal bone surface using a minimally invasive tunnelling technique. The cement pastes were stable on the bone surface and hardened soon after they were injected thereby negating the need for additional supports such as membranes or meshes. The animals were sacrificed 8 weeks after the intervention and histological observations revealed signs of successful vertical bone augmentation. Therefore, we have demonstrated a minimally invasive vertical bone augmentation procedure that is an attractive alternative to current surgical procedures in terms of increased simplicity, reduced trauma, and lower cost of surgery.

  20. High belite cement from alternative raw materials

    Directory of Open Access Journals (Sweden)

    Ghorab, H. Y.

    2014-05-01

    Full Text Available Three high belite laboratory clinkers were prepared from traditional and alternative raw materials. Reference clinker was obtained from 77% limestone, 11% sandy clays, 11% fatty clays and 1% iron scales. The fatty clays were replaced by red brick powder in the raw meal of the second clinker and were lowered to 2% with the replacement of 10% of the limestone by egg shells in the third clinker. The SEM examination revealed clear presence of crossed striae and twinning in the rounded belite grains of the reference clinker caused by the transformation of the α´-belite to the β polymorph. Striae were weaker in the second and third clinkers indicating a probable stabilization of the α ‘-belite polymorph. Compressive strength of the respective cements were attained first after 28 days and the early strength did not improve with increasing fineness. Higher compressive strength values were found for the cement prepared from second clinker.Se han preparado tres clinkeres de laboratorio con altos contenidos en belita a partir de materias primas tradicionales y alternativas. El clinker de referencia se obtuvo a partir de una mezcla de caliza, arcillas arenosas y grasas y limaduras de hierro. Las arcillas grasas fueron sustituidas por polvo de ladrillo rojo en la preparación del segundo clinker, y en el tercero el contenido de arcilla grasa fue de solo un 2% y parte de la caliza fue sustituida por cascara de huevo. El estudio realizado por SEM muestra superficies estriadas alrededor de los granos de belita que indican una transformación del polimorfo α´ a la forma β-C₂S, durante el enfriamiento. Esas estrías son menos marcadas en el segundo y tercer clinker, indicando, una estabilización del polimorfo α´-C₂S. Los valores de resistencias a compresión de los correspondientes cementos, a 28 días de curado, no se ven incrementados por la finura de dichos cementos. Las mayores resistencias se obtuvieron en el cemento preparado a partir del cl

  1. 掺合料和水胶比对水泥基材料水化产物和力学性能的影响%Influence of admixture and water-cement ratio on hydration products and mechanical properties of cement-based materials

    Institute of Scientific and Technical Information of China (English)

    吴福飞; 侍克斌; 董双快; 陈亮亮; 慈军; 王欣; 张凯

    2016-01-01

    Admixture and water-cement ratio are important factors affecting the development of properties of cement mortar or concrete. In order to study the influence of admixtures and water-cement ratio on the hydration products and the mechanical properties of cement-based materials, the study combined hydration reaction mechanism of pure cement and silicate admixture, derived the formulae of hydration products, theoretical maximum mixing amount and total porosity of composite cement-based materials, and investigated the effects of mixing amount of cement mortar with fly ash, steel slag and lithium slag on total porosity, mechanical properties and hydration products. This paper designed 3 gradients of water-cement ratio (0.50, 0.42 and 0.34), 3 kinds of admixtures (lithium slag, fly ash and steel slag) and 2 contents (20% and 60%); the ratio of cementitious material to sand was 1:2.5, and then, molding specimen accorded with the mix of mortar in the triple mold and the mechanical properties of mortar were tested when specimen was cured to 1, 3, 7, 28 and 90 d. The results showed that, after the same content of fly ash, steel slag and lithium slag incorporation, the contents of hydration products of composite cementitious materials, i.e. calcium hydroxide (CH) and calcium silicate hydrate (CSH), and the total porosity were smaller than those of pure cement; when the water-cement ratio decreased from 0.50 to 0.34, the total porosity of cement mortar decreased from 16.0% to 9.3%, and the contents of CH and CSH increased for the compound cement-based materials with mixing amount of 5%, but the increments were not big; the porosity of fly ash, steel slag and lithium slag cement-based composite materials reduced from 16.6%, 17.2% and 16.0% to 9.9%, 10.9% and 9.3%, respectively. When the admixture amount increased to 10%, the variation of porosity and hydration products of the 3 kinds of mortar was different. The content of hydration products (CH and CSH) of composite

  2. Design of Digital Control System for Cement Raw Material Preparation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ying; LI Hongsheng

    2006-01-01

    This paper describes the design of cement raw material prepared digital control system by PROFIBUS. It uses the digital technology to implement the digital control system for raw material prepared of the cement factory. This system improves the communication between the industrial system and locale instrument devices. It applies digital communication to replace the 4-20 mA or 24VDC signal between locale lever device and controller.

  3. PURIFIED WASTE FCC CATALYST AS A CEMENT REPLACEMENT MATERIAL

    Directory of Open Access Journals (Sweden)

    Danute Vaiciukyniene

    2015-06-01

    Full Text Available Zeolites are commonly used in the fluid catalytic cracking process. Zeolite polluted with oil products and became waste after some time used. The quantity of this waste inevitably rises by expanding rapidly oil industry. The composition of these catalysts depends on the manufacturer and on the process that is going to be used. The main factors retarding hydration process of cement systems and modifying them strength are organic compounds impurities in the waste FCC catalyst. The present paper shows the results of using purified waste FCC catalyst (pFCC from Lithuania oil refinery, as Portland cement replacement material. For this purpose, the purification of waste FCC catalyst (FCC samples was treated with hydrogen peroxide. Hydrogen peroxide (H2O2 is one of the most powerful oxidizers known. By acting of waste with H2O2 it can eliminate the aforementioned waste deficiency, and the obtained product becomes one of the most promising ingredients, in new advanced building materials. Hardened cement paste samples with FCC or pFCC were formed. It was observed that the pFCC blended cements developed higher strength, after 28 days, compared to the samples with FCC or reference samples. Typical content of Portland cement substituting does not exceed 30 % of mass of Portland cement in samples. Reducing the consumption of Portland cement with utilizing waste materials is preferred for reasons of environmental protection.

  4. Reinforcement of cement-based matrices with graphite nanomaterials

    Science.gov (United States)

    Sadiq, Muhammad Maqbool

    Cement-based materials offer a desirable balance of compressive strength, moisture resistance, durability, economy and energy-efficiency; their tensile strength, fracture energy and durability in aggressive environments, however, could benefit from further improvements. An option for realizing some of these improvements involves introduction of discrete fibers into concrete. When compared with today's micro-scale (steel, polypropylene, glass, etc.) fibers, graphite nanomaterials (carbon nanotube, nanofiber and graphite nanoplatelet) offer superior geometric, mechanical and physical characteristics. Graphite nanomaterials would realize their reinforcement potential as far as they are thoroughly dispersed within cement-based matrices, and effectively bond to cement hydrates. The research reported herein developed non-covalent and covalent surface modification techniques to improve the dispersion and interfacial interactions of graphite nanomaterials in cement-based matrices with a dense and well graded micro-structure. The most successful approach involved polymer wrapping of nanomaterials for increasing the density of hydrophilic groups on the nanomaterial surface without causing any damage to the their structure. The nanomaterials were characterized using various spectrometry techniques, and SEM (Scanning Electron Microscopy). The graphite nanomaterials were dispersed via selected sonication procedures in the mixing water of the cement-based matrix; conventional mixing and sample preparation techniques were then employed to prepare the cement-based nanocomposite samples, which were subjected to steam curing. Comprehensive engineering and durability characteristics of cement-based nanocomposites were determined and their chemical composition, microstructure and failure mechanisms were also assessed through various spectrometry, thermogravimetry, electron microscopy and elemental analyses. Both functionalized and non-functionalized nanomaterials as well as different

  5. Thermophysical and Mechanical Properties of Hardened Cement Paste with Microencapsulated Phase Change Materials for Energy Storage

    Directory of Open Access Journals (Sweden)

    Hongzhi Cui

    2014-12-01

    Full Text Available In this research, structural-functional integrated cement-based materials were prepared by employing cement paste and a microencapsulated phase change material (MPCM manufactured using urea-formaldehyde resin as the shell and paraffin as the core material. The encapsulation ratio of the MPCM could reach up to 91.21 wt%. Thermal energy storage cement pastes (TESCPs incorporated with different MPCM contents (5%, 10%, 15%, 20% and 25% by weight of cement were developed, and their thermal and mechanical properties were studied. The results showed that the total energy storage capacity of the hardened cement specimens with MPCM increased by up to 3.9-times compared with that of the control cement paste. The thermal conductivity at different temperature levels (35–36 °C, 55–56 °C and 72–74 °C decreased with the increase of MPCM content, and the decrease was the highest when the temperature level was 55–56 °C. Moreover, the compressive strength, flexural strength and density of hardened cement paste decreased with the increase in MPCM content linearly. Among the evaluated properties, the compressive strength of TESCPs had a larger and faster degradation with the increase of MPCM content.

  6. Pullout behavior of steel fibers from cement-based composites

    DEFF Research Database (Denmark)

    Shannag, M. Jamal; Brincker, Rune; Hansen, Will

    1997-01-01

    A comprehensive experimental program on pullout tests of steel fibers from cement based matrices is described. A specially designed single fiber pullout apparatus was used to provide a quantitative determination of interfacial properties that are relevant to toughening brittle materials through f...

  7. Histological evaluation of direct pulp capping with novel nanostructural materials based on active silicate cements and Biodentine® on pulp tissue

    Directory of Open Access Journals (Sweden)

    Popović-Bajić Marijana

    2013-01-01

    Full Text Available The aim of this study was to examine the effect of Biodentine® and two new nanostructured materials based on active silicate cements on exposed tooth pulp of Vietnamese pigs. The study comprised 40 teeth in two Vietnamese pigs (24 months old. After class V cavity preparation, the pulp on each tooth was exposed using a small round bur. The following materials were applied on pulp exposures: Biodentine® (10 teeth, ALBO MPCA-I (10 teeth, and ALBO MPCA-II (10 teeth. In the control group, exposed pulp was covered with ProRoot MTA® (10 teeth. After the observation period of 28 days, the animals were sacrificed and the teeth prepared for histological analysis. Light microscope was used for the analysis of dentin bridge formation, tissue reorganization and inflammation, and the presence of bacteria in the pulp. In the group of Biodentine®, a complete dentin bridge was noted in 3 cases, while incomplete dentin bridge in the form of dental islets was detected in 4 cases. Nanostructured material ALBO-MPCA I provided complete dentin bridge formation in 5 teeth, in 3 teeth the formed dentin bridge was incomplete. ALBO MPCA-II showed complete closure of the pulp opening by dentin bridge in 4 samples, while in the same number of teeth it was incomplete. In the control group, 4 teeth showed a complete dentin bridge, whereas in 6 teeth it was incomplete. Histological analysis indicated favourable therapeutic effects of Biodentine® and the two materials ALBO-MPCA I and ALBO-MPCA II after teeth pulp capping in Vietnamese pigs. Pulp reaction was similar to that caused by ProRoot MTA®. [Projekat Ministarstva nauke Republike Srbije, br. ON172026

  8. Utilization of Palm Oil Clinker as Cement Replacement Material

    Directory of Open Access Journals (Sweden)

    Jegathish Kanadasan

    2015-12-01

    Full Text Available The utilization of waste materials from the palm oil industry provides immense benefit to various sectors of the construction industry. Palm oil clinker is a by-product from the processing stages of palm oil goods. Channelling this waste material into the building industry helps to promote sustainability besides overcoming waste disposal problems. Environmental pollution due to inappropriate waste management system can also be drastically reduced. In this study, cement was substituted with palm oil clinker powder as a binder material in self-compacting mortar. The fresh, hardened and microstructure properties were evaluated throughout this study. In addition, sustainability component analysis was also carried out to assess the environmental impact of introducing palm oil clinker powder as a replacement material for cement. It can be inferred that approximately 3.3% of cement production can be saved by substituting palm oil clinker powder with cement. Reducing the utilization of cement through a high substitution level of this waste material will also help to reduce carbon emissions by 52%. A cleaner environment free from pollutants can be created to ensure healthier living. Certain industries may benefit through the inclusion of this waste material as the cost and energy consumption of the product can be minimized.

  9. In vivo characterization of polymer based dental cements

    Directory of Open Access Journals (Sweden)

    Widiyanti P

    2011-12-01

    Full Text Available Background: In vivo studies investigating the characterization of dental cements have been demonstrated. As few in vitro studies on this cement system have been performed. Previous researches in dental material has been standardized dental cement which fulfilled the physical and mechanical characteristic such as shear strength but were on in vitro condition, the animal model and clinical study of dental cement from laboratory has not been done yet. This research examined physical and mechanical characteristic in vivo using rabbit by making the caries (class III in anterior teeth especially in mesial or distal incisive, fulfilled the cavity by dental cement and analyzed the compressive strength, tensile strength, and microstructure using scanning electron microscope (SEM. Purpose: This study is aimed to describe the in vivo characterization of dental cements based on polymer (zinc phosphate cement, polycarboxylate, glass ionomer cement and zinc oxide eugenol. Methods: First, preparation was done on animal model’s teeth (6 rabbits, male, 5 months old. The cavity was made which involved the dentin. Then the cavity was filled with dental cement. After the filling procedure, the animal model should be kept until 21 days and than the compressive test, tensile test and microstructure was characterized. Compressive test and tensile test was analyzed using samples from extracted tooth and was measured with autograph. The microstructure test was measured using SEM. Results: The best compressive strength value was belongs to zinc phosphate cement which was 101.888 Mpa and the best tensile strength value was belongs to glass ionomer cement which was 6.555 Mpa. Conclusion: In conclusion, comparing with 3 others type of dental cements which are zinc phosphate, polycarboxylate and glass ionomer cement, zinc oxide eugenol cement has the worst for both physical and mechanical properties.Latar belakang: Studi in vivo meneliti karakterisasi secara in vivo dari

  10. On the use of crystalline admixtures in cement based construction materials: from porosity reducers to promoters of self healing

    Science.gov (United States)

    Ferrara, Liberato; Krelani, Visar; Moretti, Fabio

    2016-08-01

    The project detailed in this paper aims at a thorough characterization of the effects of crystalline admixtures, currently employed as porosity reducing admixtures, on the self-healing capacity of the cementitious composites, i.e. their capacity to completely or partially re-seal cracks and, in case, also exhibit recovery of mechanical properties. The problem has been investigated with reference to both a normal strength concrete (NSC) and a high performance fibre reinforced cementitious composite (HPFRCC). In the latter case, the influence of flow-induced fibre alignment has also been considered in the experimental investigation. With reference to either 3-point (for NSC) or 4-point (for HPFRCC) bending tests performed up to controlled crack opening and up to failure, respectively before and after exposure/conditioning recovery of stiffness and stress bearing capacity has been evaluated to assess the self-healing capacity. In a durability-based design framework, self-healing indices to quantify the recovery of mechanical properties will also be defined. In NSC, crystalline admixtures are able to promote up to 60% of crack sealing even under exposure to open air. In the case of HPFRCCs, which would already feature autogenous healing capacity because of their peculiar mix compositions, the synergy between the dispersed fibre reinforcement and the action of the crystalline admixture has resulted in a likely ‘chemical pre-stressing’ of the same reinforcement, from which the recovery of mechanical performance of the material has greatly benefited, up to levels even higher than the performance of the virgin un-cracked material.

  11. Clean Development Mechanism: Laterite as Supplementary Cementing Material (SCM

    Directory of Open Access Journals (Sweden)

    Syed Zaighum Abbass

    2013-02-01

    Full Text Available Carbon dioxide (CO2 a major Green House Gas (GHG in the atmosphere, is believed to be largely responsible for global climate change through industrial emissions. The level of CO2 concentration has exponentially increased from about 280 ppm at the start of the industrial revolution to about 380 ppm to date. Although Kyoto protocol has bound industrialized nations to reduce green house gas emissions by 5.2% below 1990 levels around year 2008-2012, but violation continues. The cement industry is one of the major emitter of green house gases, particularly CO2 due to its energy intensive production process. It is estimated that approximately 1 tone of CO2 is released during the manufacturing of each tone of Portland cement. Most of CO2 emissions originate from burning fossil fuels and de-carbonization of limestone in a cement plant. During past several decades, the use of by-product materials in concrete, either as components of blended cements or as admixtures, has increased significantly. In this study, another alternate Supplementary Cementing Material (SCM, Laterite has been used with the objectives: to evaluate the performance of cement containing different percentages of laterite (5, 10, 15, 20, 25, and 30 %; to identify the optimum replacement percentage; and to investigate the effects of different concentrations of laterite on various properties of cement. For that purpose, laterite was tested: before blending (for elemental and mineralogical composition by using XRF, SEM and XRD: after blending (Elemental analysis using XRF, fineness test by using Blaine’s air permeability test and for particle size % on 45, 90 and 200 µ sieve, respectively; and after hydration (for mineralogical analysis using SEM. Furthermore, physical tests of manufactured cement, i.e., water consistency, setting time, Le-Chatlier-expansion and compressive strength were also evaluated and compared with limestone and fly-ash cement blends. The results show that with the

  12. Response of a PGNAA setup for pozzolan-based cement concrete specimens

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)], E-mail: aanaqvi@kfupm.edu.sa; Garwan, M.A. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Maslehuddin, M. [Center for Engineering Research, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Nagadi, M.M. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Al-Amoudi, O.S.B. [Department of Civil Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Raashid, M. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

    2010-04-15

    Pozzolanic materials are added to Portland cement concrete to increase its durability, particularly corrosion-resistance. In this study the elemental composition of a pozzolanic cement concrete was measured non-destructively utilizing an accelerator-based Prompt Gamma Ray Neutron Activation Analysis (PGNAA) setup. The optimum size of the pozzolanic cement concrete specimen was obtained through Monte Carlo simulations. The simulation results were experimentally verified through the {gamma}-ray yield measurement from the pozzolanic cement concrete specimens as a function of their radii. The concentration of the pozzolanic material in the cement concrete specimens was evaluated by measuring {gamma}-ray yield for calcium and iron from pozzolanic cement concrete specimens containing 5-80 wt% pozzolan. A good agreement was noted between the experimental values and the Monte Carlo simulation results, indicating an excellent response of the KFUPM accelerator-based PGNAA setup for pozzolan based concrete.

  13. Response of a PGNAA setup for pozzolan-based cement concrete specimens.

    Science.gov (United States)

    Naqvi, A A; Garwan, M A; Maslehuddin, M; Nagadi, M M; Al-Amoudi, O S B; Raashid, M

    2010-01-01

    Pozzolanic materials are added to Portland cement concrete to increase its durability, particularly corrosion-resistance. In this study the elemental composition of a pozzolanic cement concrete was measured non-destructively utilizing an accelerator-based Prompt Gamma Ray Neutron Activation Analysis (PGNAA) setup. The optimum size of the pozzolanic cement concrete specimen was obtained through Monte Carlo simulations. The simulation results were experimentally verified through the gamma-ray yield measurement from the pozzolanic cement concrete specimens as a function of their radii. The concentration of the pozzolanic material in the cement concrete specimens was evaluated by measuring gamma-ray yield for calcium and iron from pozzolanic cement concrete specimens containing 5-80 wt% pozzolan. A good agreement was noted between the experimental values and the Monte Carlo simulation results, indicating an excellent response of the KFUPM accelerator-based PGNAA setup for pozzolan based concrete.

  14. Development and Evaluation of Cement-Based Materials for Repair of Corrosion-Damaged Reinforced Concrete Slabs

    OpenAIRE

    Liu, Rongtang; Olek, J.

    2001-01-01

    In this study, the results of an extensive laboratory investigation conducted to evaluate the properties of concrete mixes used as patching materials to repair reinforced concrete slabs damaged by corrosion are reported. Seven special concrete mixes containing various combinations of chemical or mineral admixtures were developed and used as a patching material to improve the durability of the repaired slabs. Physical and mechanical properties of these mixes, such as compressive strength, stat...

  15. Natural Radioactivity in Tanzania Cements and their Raw Materials

    Directory of Open Access Journals (Sweden)

    Aloyce Isaya Amasi

    2014-10-01

    Full Text Available This paper presents the study of natural radioactivity in Tanzania Portland cements and their raw materials. Samples collected as raw materials were pozzolan, sandstone, limestone, clay, gypsum and cement as finished products. The natural radioactivity due to the presence of radium 226Ra, thorium 232Th and potassium 40K were measured by means of gamma spectrometer coupled with HPGe detector. The mean measured activity concentrations of 226Ra, thorium 232Th and potassium 40K in the raw materials range from 2.6 to 93.2, 1.3 to 172.8 and 6.3 to 997 Bq/kg, respectively with higher activity concentrations in pozzolan and lower in gypsum. Activity concentrations of natural radionuclides in raw materials (excluding some materials from Songwe deposits in Mbeya region are comparative with the worldwide average concentrations of these radionuclides in soil. The average activity concentration of 226Ra, thorium 232Th and potassium 40K in the cements are 46, 28 and 228 Bq/kg, respectively. The calculated values of radiological indices are below 60% of the upper recommended values for building materials. The average annual effective dose to an occupant from use of these materials equals to 0.45 mSv. Average activity concentrations of the mentioned radionuclides in Tanzania cements are in the middle of the variability interval of the national averages.

  16. By-product materials in cement clinker manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Gadayev, A. [ICS and E, Aurora, CO (United States); Kodess, B. [VNIIMS Gosstandart of Russia, Moscow (Russian Federation)

    1999-02-01

    The use of Cl- and SO{sub 3}-containing by-products from chemical industries for manufacturing Portland cement clinker using a wet process was examined. The chemical and mineralogical compositions of the by-products and raw materials were determined. Homogeneous raw mixes containing different concentrations of by-products (5--30%) were prepared and the influence of the by-products on all steps of burning the mixes in a kiln to form a cement clinker was investigated. It was shown that introducing Cl- and SO{sub 3}-containing by-products to the raw mixes significantly changes all the cement clinker producing stages and changes the chemical and mineralogical compositions at all intermediate stages and in the finished products, forming new minerals containing Cl and SO{sub 3} [CaO{sub x} (SiO{sub 2}){sub y} CaCl{sub 2}] or [CaO{sub x} (SiO{sub 2}){sub y} CaSO{sub 4}] and increasing the amount of well-known intermediate minerals. The presence of the chlorides and sulfates in the cement clinker burning processes removes alkali from the raw mixes, turning them to volatile forms, accelerating the raw mineral decomposition processes and accelerating the formation processes of cement minerals (C{sub 2}S, C{sub 12}A{sub 7}, C{sub 4}AF) and formation of chloride and sulfate cycles in the kiln, forming clinker liquids and decreasing the formation and growth of the main cement minerals (C{sub 3}A, C{sub 3}S). The cement clinker contains some quantity of minerals with Cl or SO{sub 3}. Their presence in the final product decreases cement quality by reducing the amount of active CaO (C) and reducing the active CaO/SiO{sub 2} ratio.

  17. A non-destructive test method to monitor corrosion products and corrosion-induced cracking in reinforced cement based materials

    DEFF Research Database (Denmark)

    Michel, Alexander; Pease, Bradley Justin; Peterova, Adela

    2011-01-01

    This paper introduces a non-destructive test method to monitor the development of corrosion products as well as the corrosion-induced formation and propagation of cracks in cementitious materials. A parametric experimental investigation (utilizing x-ray attenuation measurement technique...

  18. Utilization of Red Mud as Raw Material in the Production of Field Road Cement

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao; LUO Zhongtao; ZHANG Lei; RONG Hui; YANG Jiujun

    2016-01-01

    The total utilization amount of red mud is limited due to its high content of alkali, heavy metals and naturally occurring radioactive element. In order to rationalize the use of red mud, a typical ifeld road cement using dealkalized red mud (content of alkali lower than 1%) as raw material was ifrstly prepared in this paper. Then, a preliminary research on the radioactivity of the red mud based ifeld road cement has been carried out. For that reason, two samples of raw materials were prepared. One was with ordinary raw materials, as the control group (CG), the other was with 23w % red mud, as the experimental group (EG). The clinkers were acquired by sintering the above two raw materials at 1 400℃. Subsequently, the two types of cement prepared by the above two kinds of clinkers were tested by measuring the normal consistency, setting time, mechanical strength and drying shrinkage. Meanwhile, the hydration products of the two types of cement were examined by XRD analysis at the curing age of 6 hours, 1, 3, 7, and 28 days, respectively. The radioactivity of the two kinds of cement clinkers was then measured by gamma-ray spectrometry. The experimental results indicate that the main mineralogical phases components in the EG ifeld road cement clinkers are C3S, C2S, and C4AF, the 28 days lfexural and compressive strength of the EG ifeld road cement mortars could be up to 8.45 and 53.2 MPa, respectively. The radioactive measuring results of the EG field road cement show that the value of radium equivalent activity index (Raeq) is 254.8 Bq/Kg-1, which is lower than the upper limit.

  19. Preparation and properties of cement-based foamed insulation material%水泥基泡沫保温材料的制备与性能研究

    Institute of Scientific and Technical Information of China (English)

    李小龙; 李国忠

    2013-01-01

      试验采用物理发泡工艺,制备纤维增强泡沫水泥保温材料。研究不同水灰比、泡沫掺量和聚丙烯纤维掺量对泡沫水泥保温材料性能的影响,确定纤维增强泡沫水泥保温材料的最佳配合比。试验结果表明,当水灰比为0.39、泡沫掺量为2.0 ml/g、纤维掺量为0.9%、稳泡剂掺量为0.3%、生石灰掺量为1.5%时,泡沫水泥保温材料的干密度为324 kg/m3,3 d抗压强度为1.051 MPa,3 d抗折强度为0.611 MPa,导热系数为0.069 W/(m·K),各性能均优于JG/T 266-2011《泡沫混凝土》的要求。利用扫描电子显微镜对泡沫水泥保温材料的微观结构进行观察与分析,探讨聚丙烯纤维的作用机理。%A kind of fiber reinforced foamed cement is prepared by physical foaming process, the paper describes the effects of different water cement ratio, and the additives of foam volume and polypropylene fiber on properties of foamed cement insulating material, and determines the best proportioning of fiber reinforced foamed cement.

  20. Diffusion model for acid corrosion of cemented materials

    Energy Technology Data Exchange (ETDEWEB)

    Van Dijk, J.C.; De Moel, P.J.; Nooyen, W.F.; Nuiten, P.C.

    1986-09-25

    The acid corrosion of cemented materials is an important aspect in engineering practice. Corrosion affects the strength of materials and may cause a deterioration of water quality. This article deals with corrosion due to non-erosive acid attacks. A diffusion model is presented in which the depth of attack increases in proportion to the square root of both time, the hydronium ion concentration in the water, and the inverse of the total concentration of lime in the solid phase. Experiments verifying the model are presented. The experiments also reveal that the corrosion of asbestos cement proceeds faster as compared to concrete because of desintegration of the structure of asbestos cement. The diffusion model also worked out to be applicable for corrosion by agressive CO/sub 2/. The lower corrosion rate due to the formation of CaCO/sub 3/ can for this case be described by a lower diffusion coefficient. 4 tabs., 6 figs., 9 refs.

  1. Carbonation Resistance of Sulphoaluminate Cement-based High Performance Concrete

    Institute of Scientific and Technical Information of China (English)

    ZHANG Decheng; XU Dongyu; CHENG Xin; CHEN Wen

    2009-01-01

    The influences of water/cement ratio and admixtures on carbonation resistance of sulphoaluminate cement-based high performance concrete(HPC)were investigated.The experimental results show that with the decreasing water/cement ratio,the carbonation depth of sulphoaluminate cement-based HPC is decreased remarkably,and the carbonation resistance capability is also improved with the adding admixtures.The morphologies and structure characteristics of sulphoaluminate cement hydration products before and after carbonation were analyzed using SEM and XRD.The analysis results reveal that the main hydration product of sulphoaluminate cement,that is ettringite(AFt),de-composes after carbonation.

  2. Pit and Fissure Sealants with Different Materials: Resin Based x Glass Ionomer Cement – Results after Six Months

    Directory of Open Access Journals (Sweden)

    Priscilla Santana Pinto Gonçalves

    2016-01-01

    Full Text Available Objective: To compare the retention and superficial characteristics between a new resin-modified glass ionomer sealant and resin sealant. In addition, the teeth sealed were compared to partially erupted first molars (control group without sealing in relation to the incidence of dental caries. Material and Methods: Initially, 31 children aged 6-8 years participated in this study. The study children showed caries history, but had at least two healthy first molars. A total of 114 teeth were randomly divided into three groups: Clinpro (n=36, Fluroshield (n=38, and control (n=40. The two sealants were applied under relative isolation after previous prophylaxis and enamel etching with phosphoric acid 35% (15s. Clinical evaluation was performed by two calibrated examiners. They evaluated the retention and surface characteristics of the occlusal surface. Results: Fluroshield® showed significantly greater retention than ClinproTM Varnish® XT (p=0.002. However, the performance analysis of the success and failure of retention presented no significant difference between the materials (p=0.141. Concerning to the surface characteristics, Fluroshield performed better than Clinpro after analyzing the marginal deterioration, marginal discoloration, and superficial discoloration (p<0.05. The surface texture of the materials under study was similar (p=0.071. Sealed groups (Clinpro=Fluroshield showed similar performance in the prevention of dental caries, which was significantly lower than that of control group (p=0.001. Conclusion: Both sealants, Fluroshield® and Clinpro TM Varnish® XT were effective in preventing caries lesion within 6 months, although Fluroshield sealant showed better clinical retention.

  3. Effect of Pozzolanic Reaction of Volcanic Rocks in Cement-based Material%水泥基材料中火山岩火山灰反应的效益

    Institute of Scientific and Technical Information of China (English)

    喻乐华; 李琳国; 管亮亮; 何兵兵; 廖妙星

    2015-01-01

    Based on the concept that strength of cement-based material results from hydration of cement and pozzolanic reaction of pozzolans (secondary-hydration reaction), the mechanical strength of cement mortar blend-ed with volcanic rock powder was tested, and effect of pozzolanic reaction of volcanic rock was calculated by us-ing the strength values. The results show that the effect of pozzolanic reaction for volcanic rocks in cement-base material decreases as the dosage of volcanic rock increases and the hydration time prolongs. The relationships a-mong them are expressed quantitatively by using fitting regression equation. It finds out that from the effect val-ues of pozzolanic reaction, in most cases, replacement of cement by volcanic rocks results in reducing impacts on strength of cement-based material, and the higher the replacement volume is, the greater the strength decreases.%基于水泥基材料强度由水泥的水化反应和火山灰质材料的火山灰反应(二次水化反应)共同构成之概念,测试掺火山岩粉末的水泥砂浆力学强度计算,表征单位火山岩的火山灰反应之效益。结果表明火山岩火山灰反应的效益随着水泥基材料中掺量增大而减小,同掺量情况下随着水化时间延长而减小。这些关系可用拟合回归方程量化表达。研究的火山岩火山灰反应效益可知大多数情况下火山岩替代水泥会对水泥基材料强度有降低影响,掺量越大强度降低幅度也越大。研究成果有助于工程上优化选择火山灰质材料在水泥基材料中的应用。

  4. Determination of Diffusion Coefficients in Cement-Based Materials: An Inverse Problem for the Nernst-Planck and Poisson Models

    Science.gov (United States)

    Szyszkiewicz-Warzecha, Krzysztof; Jasielec, Jerzy J.; Fausek, Janusz; Filipek, Robert

    2016-08-01

    Transport properties of ions have significant impact on the possibility of rebars corrosion thus the knowledge of a diffusion coefficient is important for reinforced concrete durability. Numerous tests for the determination of diffusion coefficients have been proposed but analysis of some of these tests show that they are too simplistic or even not valid. Hence, more rigorous models to calculate the coefficients should be employed. Here we propose the Nernst-Planck and Poisson equations, which take into account the concentration and electric potential field. Based on this model a special inverse method is presented for determination of a chloride diffusion coefficient. It requires the measurement of concentration profiles or flux on the boundary and solution of the NPP model to define the goal function. Finding the global minimum is equivalent to the determination of diffusion coefficients. Typical examples of the application of the presented method are given.

  5. Surface Hardness of Resin Cement Polymerized under Different Ceramic Materials

    Directory of Open Access Journals (Sweden)

    Pimmada Kesrak

    2012-01-01

    Full Text Available Objectives. To evaluate the surface hardness of two light-cured resin cements polymerized under different ceramic discs. Methods. 40 experimental groups of 2 light-cured resin cement specimens (Variolink Veneer and NX3 were prepared and polymerized under 5 different ceramic discs (IPS e.max Press HT, LT, MO, HO, and Cercon of 4 thicknesses (0.5, 1.0, 1.5, and 2.0 mm, Those directly activated of both resin cements were used as control. After light activation and 37∘C storage in an incubator, Knoop hardness measurements were obtained at the bottom. The data were analyzed with three-way ANOVA, t-test, and one-way ANOVA. Results. The KHN of NX3 was of significantly higher than that of Variolink Veneer (<0.05. The KHN of resin cement polymerized under different ceramic types and thicknesses was significant difference (<0.05. Conclusion. Resin cements polymerized under different ceramic materials and thicknesses showed statistically significant differences in KHN.

  6. Cementation of Loose Sand Particles based on Bio-cement

    Institute of Scientific and Technical Information of China (English)

    RONG Hui; QIAN Chunxiang

    2014-01-01

    Loose sand particles could be cemented to sandstone by bio-cement (microbial induced magnesium carbonate). The bio-sandstone was firstly prepared, and then the compressive strength and the porosity of the sandstone cemented by microbial induced magnesium carbonate were tested to characterize the cementation effectiveness. In addition, the formed mineral composition and the microstructure of bio-sandstone were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The experimental results show that the feasibility of binding loose sand particles using microbial induced magnesium carbonate precipitation is available and the acquired compressive strength of bio-sandstone can be excellent at certain ages. Moreover, the compressive strength and the porosity could be improved with the increase of microbial induced magnesium carbonate content. XRD results indicate that the morphology of magnesium carbonate induced by microbe appears as needles and SEM results show that the cementation of loose sand particles to sandstone mainly relies on the microbial induced formation of magnesium carbonate precipitation around individual particles and at particle-particle contacts.

  7. The effect of fly ash and coconut fibre ash as cement replacement materials on cement paste strength

    Science.gov (United States)

    Bayuaji, R.; Kurniawan, R. W.; Yasin, A. K.; Fatoni, H. AT; Lutfi, F. M. A.

    2016-04-01

    Concrete is the backbone material in the construction field. The main concept of the concrete material is composed of a binder and filler. Cement, concrete main binder highlighted by environmentalists as one of the industry are not environmentally friendly because of the burning of cement raw materials in the kiln requires energy up to a temperature of 1450° C and the output air waste CO2. On the other hand, the compound content of cement that can be utilized in innovation is Calcium Hydroxide (CaOH), this compound will react with pozzolan material and produces additional strength and durability of concrete, Calcium Silicate Hydrates (CSH). The objective of this research is to explore coconut fibers ash and fly ash. This material was used as cement replacement materials on cement paste. Experimental method was used in this study. SNI-03-1974-1990 is standard used to clarify the compressive strength of cement paste at the age of 7 days. The result of this study that the optimum composition of coconut fiber ash and fly ash to substitute 30% of cement with 25% and 5% for coconut fibers ash and fly ash with similar strength if to be compared normal cement paste.

  8. Study on Strain Resistance Effect of Part-stromatolithic Carbon Fiber Cement-base Materials%局部叠层碳纤维水泥基材料的应变电阻效应研究

    Institute of Scientific and Technical Information of China (English)

    郑立霞; 朱四荣; 李卓球; 郑华升

    2011-01-01

    The continuous carbon fiber-bundle was used to replace the chopped carbon fiber in the traditional carbon fiber reinforced concrete. The changing rule of the resistance of three-point-bending beams with the part-stromatolithic carbon fiber cement-based material was studied when they were loaded on monotonous or cyclic tension stress. The strain resistance effect of part-stromatolithic carbon fiber cement-based material was analyzed and compared with that of the continuous carbon fiber cement-based materials. The results showed that the part-stromatolithic carbon fiber cement-based material was near 23 times the gauge factor of the continuous carbon fiber cement-based material, but their stability was worse. The resistance of the part-stromatolithic carbon fiber cement-based material increased along with the increase of tension strain and decreased along with the decrease of tension strain. The part-stromatolithic carbon fiber reinforced cement-based material was expected to performance the health monitoring of the civil engineering structure and infrastructure.%将碳纤维加入普通混凝土中,普通混凝土便成为具有自诊断功能特性的智能混凝土.利用这些功能特性可望实现土木工程结构和基础设施的健康监测.使用连续碳纤维束取代传统碳纤维增强混凝土中的短切碳纤维,研究了局部叠层碳纤维水泥基材料三点弯曲梁在单调和循环拉应力作用下电阻的变化规律,分析了局部叠层碳纤维水泥基材料的应变-电阻效应,并与连续碳纤维水泥基材料应变-电阻效应作了比较.结果表明,局部叠层碳纤维水泥基材料的应变灵敏系数是连续碳纤维水泥基材料应变灵敏系数的近23倍,但稳定性要差一些;局部叠层碳纤维水泥基材料的电阻随着拉伸应变的增大而增大,随着拉伸应变的减小而减小,可望用于土木工程结构和基础设施的健康监测.

  9. 粉煤灰基多元复合胶结剂在全尾砂充填中的应用%Application of Fly Ash-based Compound Cementation Materials in Total-tailing Filling

    Institute of Scientific and Technical Information of China (English)

    杨春保; 朱春启; 陈贤树

    2011-01-01

    简述了粉煤灰基多元复合胶结剂的生产工艺过程,及其在矿山全尾砂胶结充填中的应用.实践表明,粉煤灰基多元复合胶结剂性能良好、生产成本低廉,完全替代水泥用于矿山全尾砂充填,可用超低的灰砂比,有更好的流动输送性能,更低的充填成本.%The production process of the fly ash-based compound cementation material and its application in total-tailing filling are described briefly. It is indicated that fly ash-based compound cementation material had an excellent performance and a low cost. It can entirely replace cement used as mine total tailing filling with a lower ash-sand ratio, better performance of flow and transport and lower filling costs.

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

    Directory of Open Access Journals (Sweden)

    Yanwei Yang

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

  11. Preparation, Mechanical and Thermal Properties of Cement Board with Expanded Perlite Based Composite Phase Change Material for Improving Buildings Thermal Behavior

    Directory of Open Access Journals (Sweden)

    Rongda Ye

    2015-11-01

    Full Text Available Here we demonstrate the mechanical properties, thermal conductivity, and thermal energy storage performance of construction elements made of cement and form-stable PCM-Rubitherm® RT 28 HC (RT28/expanded perlite (EP composite phase change materials (PCMs. The composite PCMs were prepared by adsorbing RT28 into the pores of EP, in which the mass fraction of RT28 should be limited to be no more than 40 wt %. The adsorbed RT28 is observed to be uniformly confined into the pores of EP. The phase change temperatures of the RT28/EP composite PCMs are very close to that of the pure RT28. The apparent density and compression strength of the composite cubes increase linearly with the mass fraction of RT28. Compared with the thermal conductivity of the boards composed of cement and EP, the thermal conductivities of the composite boards containing RT28 increase by 15%–35% with the mass fraction increasing of RT28. The cubic test rooms that consist of six boards were built to evaluate the thermal energy storage performance, it is found that the maximum temperature different between the outside surface of the top board with the indoor temperature using the composite boards is 13.3 °C higher than that of the boards containing no RT28. The thermal mass increase of the built environment due to the application of composite boards can contribute to improving the indoor thermal comfort and reducing the energy consumption in the buildings.

  12. 水泥基渗透结晶材料的研究与应用现状%The Present Research and Application of Cement Based Permeated Crystalline Materials

    Institute of Scientific and Technical Information of China (English)

    尚晓华; 敬登虎

    2015-01-01

    针对混凝土结构面临的各种问题以及加固后再使用过程中面临的问题,介绍了水泥基渗透结晶材料的作用机理以及渗透深度,并探讨了水泥基渗透结晶材料对混凝土性能的影响以及面临的机遇和未来的挑战等。结果表明,水泥基渗透结晶材料从理论上来说是一种很好的加固材料,不仅能够改善混凝土现阶段的性能,并且能够抵御后续使用过程中面临的各种环境问题,但是未来混凝土技术的发展趋势,使得水泥基渗透结晶材料面临着严峻的挑战。%According to the various issues of concrete structure and some problems related to it after being strengthened , the working mechanism and the penetration depth of the cement based permeated crystalline material were introduced . Furthermore the effect of this material on the properties of the concrete and the opportunities as well as the challenges for its application in the future were also discussed .The research results indicate that the cement based permeated crystalline material in theory is a good strengthening material ,which not only can improve the performance of concrete at the present stage ,but also has the ability to resist various environmental problems emerged in the course of future process .However , with the development of concrete technology in the future ,the cement based permeated crystalline material is facing very severe challenges .

  13. 利用原状磷石膏制备石膏基复合胶凝材料的力学性能%Mechanical property of phosphogypsum based composite cementing material prepared with original phosphogypsum

    Institute of Scientific and Technical Information of China (English)

    张毅; 王小鹏; 李东旭

    2011-01-01

    Original untreated phosphogypsum was used to prepare a kind of phosphogypsum based cementing material, the mechanical property of the prepared material was tested and effects of quicklime content, water/cement ratio and molding pressure on the mechanical property were investigated. The results showed that with the quicklime content of 4%, the phosphogypsum slag composite cementing material had a good mechanical property, slag power had a positive correlation with the mechanical property of the phosphogypsum fly ash composite cementing material, and the mechanical property of the phosphogypsum slag boiler slag composite cementing material decreased as the molding pressure was greater than 3 MPa. Compared with the specimens prepared by casting molding method, the total porosity value of the specimens prepared under 5 MPa molding pressure was larger, especially for the volume fraction of more than 200 nm pore. Its microstructure would be destroyed, thus its mechanical property was decreased.%以未经处理的原状磷石膏制备磷石膏基复合胶凝材料,测试磷石膏基复合胶凝材料的力学性能,考察生石灰的掺量、水灰比以及成型压力对磷石膏基复合胶凝材料力学性能的影响.结果表明:当生石灰掺量为4%时,磷石膏-矿渣复合胶凝材料具有较好的力学性能,矿渣微粉对磷石膏-粉煤灰复合胶凝材料的力学性能有增强作用.对于磷石膏-矿渣-炉渣复合胶凝材料,当成型压力超过3MPa时,制备的材料力学性能明显下降.同浇注成型试样相比较,在5MPa成型压力下的压实成型试样,材料孔隙率提高,特别对于200nm以上孔所占体积分数来说,其所占体积分数要远远高于浇注成型试样,导致了材料微观结构劣化,力学性能变差.

  14. Thermal properties of a new ecological building material / Granular cork embedded in white cement

    Directory of Open Access Journals (Sweden)

    Cherki Abou-bakr

    2014-04-01

    Full Text Available Cork, natural and renewable product, has thermal and acoustic properties very interesting because of its microstructure and porosity representing a significant portion of its apparent volume; it’s coming from Moroccan Maamora’s forest. This work is a contribution to understand the thermal behaviour of the composite material based on granular cork embedded in white cement. An experimental investigation of its thermal properties was mainly performed using the asymmetrical device of transient Hot Plate method. The effect of granular cork size on the thermal properties of the mixture was studied. The experimental study of this sustainable material aims to characterize its thermal properties and then compare them with those of white cement without cork for motivate the proposal that this composite material will be used as walls insulator. A comparison of the energy performances of the composite material and white cement was made; it allows deducing a very interesting energy gain. The findings of the experiments indicate that the composite is better than white cement in term of thermal insulation, energy storage capacity and lightness. So, it can be used to realize the internal walls insulation. Its utilization should contribute to the improvement of the energy efficiency in building especially that this is a mixture based on a sustainable and renewable material.

  15. Durability of cement-based materials: modeling of the influence of physical and chemical equilibria on the microstructure and the residual mechanical properties; Durabilite des materiaux cimentaires: modelisation de l'influence des equilibres physico-chimiques sur la microstructure et les proprietes mecaniques residuelles

    Energy Technology Data Exchange (ETDEWEB)

    Guillon, E

    2004-09-15

    A large part of mechanical and durability characteristics of cement-based materials comes from the performances of the hydrated cement, cohesive matrix surrounding the granular skeleton. Experimental studies, in situ or in laboratory, associated to models, have notably enhanced knowledge on the cement material and led to adapted formulations to specific applications or particularly aggressive environments. Nevertheless, these models, developed for precise cases, do not permit to specifically conclude for other experimental conclusions. To extend its applicability domain, we propose a new evolutive approach, based on reactive transport expressed at the microstructure scale of the cement. In a general point of view, the evolution of the solid compounds of the cement matrix, by dissolutions or precipitations, during chemical aggressions can be related to the pore solution evolution, and this one relied to the ionic exchanges with the external environment. By the utilization of a geochemical code associated to a thermodynamical database and coupled to a 3D transport model, this approach authorizes the study of all aggressive solution. The approach has been validated by the comparison of experimental observations to simulated degradations for three different environments (pure water, mineralized water, seawater) and on three different materials (CEM I Portland cement with 0.25, 0.4 and 0.5 water-to cement ratio). The microstructural approach permits also to have access to mechanical properties evolutions. During chemical aggressions, the cement matrix evolution is traduced in a microstructure evolution. This one is represented from 3D images similarly to the models developed at NIST (National Institute of Standards and Technology). A new finite-element model, validated on previous tests or models, evaluates the stiffness of the cement paste, using as a mesh these microstructures. Our approach identifies and quantifies the major influence of porosity and its spatial

  16. High belite cement from alternative raw materials

    OpenAIRE

    Ghorab, H. Y.; Rizk, M.; Ibrahim, B.; Allam, M. M.

    2014-01-01

    Three high belite laboratory clinkers were prepared from traditional and alternative raw materials. Reference clinker was obtained from 77% limestone, 11% sandy clays, 11% fatty clays and 1% iron scales. The fatty clays were replaced by red brick powder in the raw meal of the second clinker and were lowered to 2% with the replacement of 10% of the limestone by egg shells in the third clinker. The SEM examination revealed clear presence of crossed striae and twinning in the rounded belite grai...

  17. Additives for cement compositions based on modified peat

    Energy Technology Data Exchange (ETDEWEB)

    Kopanitsa, Natalya, E-mail: kopanitsa@mail.ru; Sarkisov, Yurij, E-mail: sarkisov@tsuab.ru; Gorshkova, Aleksandra, E-mail: kasatkina.alexandra@gmail.com; Demyanenko, Olga, E-mail: angel-n@sibmail.com [Tomsk State University of Architecture and Building, 2, Solyanaya sq., Tomsk, 634003 (Russian Federation)

    2016-01-15

    High quality competitive dry building mixes require modifying additives for various purposes to be included in their composition. There is insufficient amount of quality additives having stable properties for controlling the properties of cement compositions produced in Russia. Using of foreign modifying additives leads to significant increasing of the final cost of the product. The cost of imported modifiers in the composition of the dry building mixes can be up to 90% of the material cost, depending on the composition complexity. Thus, the problem of import substitution becomes relevant, especially in recent years, due to difficult economic situation. The article discusses the possibility of using local raw materials as a basis for obtaining dry building mixtures components. The properties of organo-mineral additives for cement compositions based on thermally modified peat raw materials are studied. Studies of the structure and composition of the additives are carried out by physicochemical research methods: electron microscopy and X-ray analysis. Results of experimental research showed that the peat additives contribute to improving of cement-sand mortar strength and hydrophysical properties.

  18. Additives for cement compositions based on modified peat

    Science.gov (United States)

    Kopanitsa, Natalya; Sarkisov, Yurij; Gorshkova, Aleksandra; Demyanenko, Olga

    2016-01-01

    High quality competitive dry building mixes require modifying additives for various purposes to be included in their composition. There is insufficient amount of quality additives having stable properties for controlling the properties of cement compositions produced in Russia. Using of foreign modifying additives leads to significant increasing of the final cost of the product. The cost of imported modifiers in the composition of the dry building mixes can be up to 90% of the material cost, depending on the composition complexity. Thus, the problem of import substitution becomes relevant, especially in recent years, due to difficult economic situation. The article discusses the possibility of using local raw materials as a basis for obtaining dry building mixtures components. The properties of organo-mineral additives for cement compositions based on thermally modified peat raw materials are studied. Studies of the structure and composition of the additives are carried out by physicochemical research methods: electron microscopy and X-ray analysis. Results of experimental research showed that the peat additives contribute to improving of cement-sand mortar strength and hydrophysical properties.

  19. Characterization of microstructure of cement-based materials by multi-cycle-MIP method%水泥基材料微结构的反复压汞法表征

    Institute of Scientific and Technical Information of China (English)

    肖海军; 孙伟; 蒋金洋; 王彩辉

    2013-01-01

    In order to obtain real microstructure features of cement-based materials, multi-cycle-MIP (mercury intrusion porosimetry) method was performed to eliminate the effect of ink-bottle type pores. Under different conditions, the influence of cement fineness on the pore structure of cement paste was studied. The experimental results show that the curve of the pressure mercury of cement paste made of cement with different fineness have two peaks through the first intrusion mercury, and the peaks are corresponding to capillary pore and gel pore, respectively. When repeated intrusion mercury is performed, the height of the capillary pore peak decreases, and the aperture and the width of peak become larger. However, for the gel pore, the aperture and the width are almost unchanged while the height of the peak decreases. By using the multi-cycle-MIP method, the parameters of pore structures of cement paste made of cement with specific surface area of 1.19 and 1.78 m2/g can be properly represented, and the corresponding effective porosity is 65% -80% . However, for cement paste made of cement with specific surface area of 1.95 and 2.24 m2/g, this method fails. When the specific surface area is small, effective porosity and ink bottle porosity can be separated by using repeated MIP method. The ink bottle effect exists in both capillary pores and gel pores.%为了获得水泥基材料真实的微结构特征,采用反复压汞法来消除墨水瓶效应的影响.针对不同的工况,研究了水泥细度对水泥石微结构的影响.实验结果表明:由具有不同细度水泥制成的水泥石在第1次进汞时,其压汞曲线上均存在与毛细孔和凝胶孔相对应的2个峰值.反复压汞时,毛细孔峰高下降,孔径和峰宽变大;而凝胶孔仅峰高下降,峰值与峰宽变化不大.对于比表面积为1.19和1.78 m2/g的水泥制成的水泥石,反复压汞法可以有效表征其孔结构参数,有效孔隙率为65% ~ 80%

  20. Strength Characteristics of Marine Magnesium Phosphate Cement-based Materials and Its Microscopic Mechanism Analysis%海工磷酸镁水泥基材料强度特性及其微观机理分析

    Institute of Scientific and Technical Information of China (English)

    蒋江波; 薛明; 汪宏涛; 曹巨辉

    2013-01-01

    Magnesium phosphate cement-based materials were prepared using sea sand and sea water, then curing under nature and sea water in the marine climate and environment. Through test and analysis of strength properties, microstructure and composition of the materials,the long-term strength development, anti-sea erosion properties and microscopic mechanism of the materials were researched. The results show that: the sea sand and sea water have little effect on the mechanical properties of the materials, the materials have good long-term strength development, the compressive strength of the material hydrating for 7 d curing under the nature is more than 43 MPa, the compressive strength of the material hydrating for 900 d curing under the nature is about 90 MPa. The marine magnesium phosphate cement-based materials have good anti-sea erosion performance, the compressive strength of the magnesium phosphate cement mortar hydrating for 900 d curing under seawater is 37. 9 MPa. The relationship between microscopic composition and macroscopic properties of the materials were established initially, accordingly lay a theoretical foundation for further improving the application features of the materials.%将采用海砂、海水制备的海工磷酸镁水泥基材料,分别在海洋气候环境下自然养护和海水中浸泡养护,通过对材料强度特性、微观结构及组成的测试分析,研究材料的长期强度发展规律、抗海水侵蚀性能及其微观作用机理.结果表明:海工磷酸镁水泥基材料的力学性能受海砂、海水的影响不大,材料长期强度发展较好,自然养护下材料7d的抗压强度达到43MPa以上,900 d的抗压强度达到90MPa左右;海工磷酸镁水泥基材料抗海水侵蚀性能较好,海水浸泡养护900 d时抗压强度达到37.9 MPa;初步建立了材料微观组成结构与宏观特性的关系,为进一步提高材料应用特性打下理论基础.

  1. The sealing ability of novel Kryptonite adhesive bone cement as a retrograde filling material

    Science.gov (United States)

    Uzun, İsmail; Keskin, Cangül; Güler, Buğra

    2016-01-01

    Background. This study evaluated the ability of Kryptonite bone cement in sealing retrograde cavities. Methods. The root canals of one hundred extracted human maxillary incisor teeth were instrumented up to master apical file #40 using Mtwo rotary system and obturated with gutta-percha and AHPlus sealer by cold lateral compaction method. The specimens were assigned to one control group and four experimental groups based on the retrograde filling materials (n=20). The specimens were immersed in 0.5% Rhodamine B solution for 48h. Then the specimens were divided longitudinally into two parts and the depth of dye penetration was assessed under ×10 magnification. Data were analyzed using one-way ANOVA and Bonferroni tests. Results. There were statistically significant difference between the experimental groups and the control group (P0.05). Conclusion. Kryptonite cement provided optimal apical seal in a manner similar to MTA, amalgam and IRM when used as a retrograde filling cement. PMID:27651886

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-12-01

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

  3. 新型水泥基材料耐久性的预测%Predicting Durability of Novel Cement-Based Materials

    Institute of Scientific and Technical Information of China (English)

    George W SCHERER

    2012-01-01

    普通硅酸盐水泥(OPC)混凝土的耐久性已经历了一个世纪的试验验证和基础性研究,对一些破坏过程(如冻融)已有了较为深入的了解,但对多数破坏过程还只是泛泛的了解。在已有研究的基础上,通过试验,建立可行的模型,揭示材料的物理性质(如:扩散系数、结晶速率、化学势)可以加快研究的进程。这种方法对于新型水泥基材料的研究和开发尤为重要。新型水泥基材料的长期性能不能直接用OPC的经验模型,要用基于成熟的机理和可测量的物理性能来预测。OPC研究已经揭示了控制新型水泥基材料性能的参数,同时参考全面的数值模拟分析方法能够描述材料的真实行为。建立基于实验测试其性能的模型有利于研究和开发新型水泥基材料。本文综述了几种破坏类型(冻融、盐结晶,锈蚀)的模型及所需量化的性能参数。%Understanding of the durability of OPC concrete has developed over more than a century of empirical testing and basic research, with the result that some deterioration processes (e.g., freezing) are quite well understood, and most are broadly understood. Given this foundation, progress can be accelerated by focusing on tests that reveal the physical properties (e.g., diffusivity, nucleation rates, and chemical potentials) that are needed in realistic models. This approach is particularly important for the development of novel cementitious systems. The long-term behavior of new systems cannot be predicted from empirical models developed for OPC; rather, it is essential to use models based on established mechanisms and measurable physical properties. Experience with OPC has revealed the nature of the factors that will control the behavior of novel cements, and numerical simulations are increasingly capable of describing real behavior by incorporating essential degrees of complexity. Rapid introduction of new materials will be

  4. Polymer-cement geothermal-well-completion materials. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Zeldin, A.N.; Kukacka, L.E.

    1980-07-01

    A program to develop high-temperature polymer cements was performed. Several formulations based on organic and semi-inorganic binders were evaluated on the basis of mechanical and thermal stability, and thickening time. Two optimized systems exhibited properties exceeding those required for use in geothermal wells. Both systems were selected for continued evaluation at the National Bureau of Standards and contingent upon the results, for field testing in geothermal wells.

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

    Directory of Open Access Journals (Sweden)

    Mejía de Gutiérrez, R.

    2003-12-01

    Full Text Available Failure of concrete after a period of years, less than the life expected for which it was designed, may be caused by the environment to which it has been exposed or by a variety of internal causes. The incorporation of supplementary materials has at the Portland cement the purpose of improving the concrete microstructure and also of influence the resistance of concrete to environmental attacks. Different mineral by-products as ground granulated blast furnace slag (GGBS, silica fume (SF, metakaolin (MK, fly ash (FA and other products have been used as supplementary cementing materials. This paper is about the behavior of concrete in the presence of mineral additions. Compared to Portland cements, blended cements show lower heat of hydration, lower permeability, greater resistance to sulphates and sea water. These blended cements find the best application when requirements of durability are regarded as a priority specially on high performance concrete.

    La falla del concreto en un tiempo inferior a la vida útil para la cual se diseñó puede ser consecuencia del medio ambiente al cual ha estado expuesto o de algunas otras causas de tipo interno. La incorporación de materiales suplementarios al cemento Portland tiene el propósito de mejorar la microestructura del concreto y también de contribuir a la resistencia del concreto a los ataques del medio ambiente. Diferentes minerales y subproductos tales como escorias granuladas de alto horno, humo de sílice, metacaolín, ceniza volante y otros productos han sido usados como materiales suplementarios cementantes. Este documento presenta el comportamiento del hormigón en presencia de diferentes adiciones. Los cementos adicionados, comparados con los cementos Portland muestran bajos calores de hidratación, baja permeabilidad, mayor resistencia a sulfatos y a agua de mar. Estos cementos adicionados encuentran un campo de aplicación importante cuando los requerimientos de durabilidad son

  6. 水泥基复合保温材料的防水性能研究%Study on the waterproofing properties of thermal insulation cement-based composite materials

    Institute of Scientific and Technical Information of China (English)

    李静; 李国忠

    2015-01-01

    Polystyrene granules (EPS) for lightweight aggregate and cement for cementing material, while adding a variety of additives, were used to prepare cement-based composite thermal insulation materials by the method of vibration molding. The effects of different waterproof agent on water absorption, flexural softening resistance coefficient and strength of cement-based composite thermal insulation materials were studied contrastively by adding emulsified stearic acid and emulsified composite waterproofing agent, and the related mechanisms were analyzed. Results showed that the waterproofing effect and strengthen effect of emulsified composite waterproofing agent is superior to emulsified stearic acid, when the content of emulsified stearic acid and emulsified composite waterproofing agent are 5% and 5%, respectively, the 2h, 24h water absorption of samples are 20.59%, 47.64%and 15.53%, 34.53%, the flexural softening resistance coefficient of samples are 0.71 and 0.75, the flexural and compressive strength of samples are 0.32MPa, 0.42MPa and 0.35MPa, 0.47MPa respectively.%以聚苯乙烯颗粒(EPS)为轻骨料、水泥为胶凝材料,同时掺加多种外加剂,经振动成型制备水泥基复合保温材料,通过掺加乳化硬脂酸和乳化复合防水剂,对比研究了不同防水剂对水泥基复合保温材料吸水率、抗折软化系数和强度的影响,并对其相关作用机理进行了分析。结果表明:乳化复合防水剂的防水效果和增强效果均明显优于乳化硬脂酸,当乳化硬脂酸和乳化复合防水剂掺量分别为5%和5%时,试样的2 h、24 h吸水率分别为20.59%、47.64%和15.53%、34.53%,试样的抗折软化系数分别为0.71和0.75,试样的抗折、抗压强度分别为0.32 MPa、0.42 MPa和0.35 MPa、0.47 MPa。

  7. Research Progress on Application of Metakaolin in the Field of Cement-based Materials%偏高岭土在水泥基材料中应用的研究进展

    Institute of Scientific and Technical Information of China (English)

    王子嘉

    2013-01-01

    The influence of porpsity,mechanical properties and hydration characteristics of cement-based materials made with metakaolin along with its pozzolanic activity and activation process were reviewed.The emphasis was placed on the durability of cement-based material made with metakaolin,including anti-chloride penetration,anti-sulphate attack,anti-ASR attack and shrinkage.In addition,the aspects for future development and application are proposed.%对偏高岭土的火山灰活性,煅烧工艺,及其对水泥基材料孔结构,水化过程,力学性能的影响进行了综述.详细总结了偏高岭土改性水泥基材料耐久性能的研究进展,包括抗氯离子渗透性能,抗硫酸盐侵蚀性能,抗碱硅酸反应性能,及改性材料的收缩性能,最后提出了偏高岭土矿物掺合料未来的发展趋势并对应用前景进行了展望.

  8. Bond Mechanisms in Fiber Reinforced Cement-Based Composites

    Science.gov (United States)

    1989-08-01

    Symposium on "Cement Based Composites: Bonding in Cementitious Composites," S. Mindess and S. Shah, Editors. 44. Nilson, A. H., "Bond Stress-Slip...Society Symposium on "Cement Based Composites: Bonding in Cementitious Composites," held in Boston, December 2 to 4, 1987, S. Mindess and S. Shah, 0

  9. Spalling Resistant Bauxite Based Bricks for Cement Kiln

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiaohui; Peng Xigao

    2011-01-01

    @@ 1.Scope This standard specifies the term,definition,classification,labeling,technical requirements,test methods,inspection rules,packing,marking,transportation,storage,and quality certificate of spalling resistant bauxite based bricks for cement kiln.This standard is applicable to the spalling resistant bauxite based bricks for cement kiln.

  10. Microindentation of Polymethyl Methacrylate (PMMA Based Bone Cement

    Directory of Open Access Journals (Sweden)

    F. Zivic

    2011-12-01

    Full Text Available Characterization of polymethyl methacrylate (PMMA based bone cement subjected to cyclical loading using microindentation technique is presented in this paper. Indentation technique represents flexible mechanical testing due to its simplicity, minimal specimen preparation and short time needed for tests. The mechanical response of bone cement samples was studied. Realised microindentation enabled determination of the indentation testing hardness HIT and indentation modulus EIT of the observed bone cement. Analysis of optical photographs of the imprints showed that this technique can be effectively used for characterization of bone cements.

  11. THE USE OF SISAL FIBRE AS REINFORCEMENT IN CEMENT BASED COMPOSITES

    Directory of Open Access Journals (Sweden)

    Romildo Dias Tolêdo Filho

    1999-08-01

    Full Text Available ABSTRACT The inclusion of fibre reinforcement in concrete, mortar and cement paste can enhance many of the engineering properties of the basic materials, such as fracture toughness, flexural strength and resistance to fatigue, impact, thermal shock and spalling. In recent years, a great deal of interest has been created worldwide on the potential applications of natural fibre reinforced, cement based composites. Investigations have been carried out in many countries on various mechanical properties, physical performance and durability of cement based matrices reinforced with naturally occurring fibres including sisal, coconut, jute, bamboo and wood fibres. These fibres have always been considered promising as reinforcement of cement based matrices because of their availability, low cost and low consumption of energy. In this review, the general properties of the composites are described in relation to fibre content, length, strength and stiffness. A chronological development of sisal fibre reinforced, cement based matrices is reported and experimental data are provided to illustrate the performance of sisal fibre reinforced cement composites. A brief description on the use of these composite materials as building products has been included. The influence of sisal fibres on the development of plastic shrinkage in the pre-hardened state, on tensile, compressive and bending strength in the hardened state of mortar mixes is discussed. Creep and drying shrinkage of the composites and the durability of natural fibres in cement based matrices are of particular interest and are also highlighted. The results show that the composites reinforced with sisal fibres are reliable materials to be used in practice for the production of structural elements to be used in rural and civil construction. This material could be a substitute asbestos-cement composite, which is a serious hazard to human and animal health and is prohibited in industrialized countries. The

  12. Properties of Cement Mortar Produced from Mixed Waste Materials with Pozzolanic Characteristics

    OpenAIRE

    2012-01-01

    Waste materials with pozzolanic characteristics, such as sewage sludge ash (SSA), coal combustion fly ash (FA), and granulated blast furnace slag (GBS), were reused as partial cement replacements for making cement mortar in this study. Experimental results revealed that with dual replacement of cement by SSA and GBS and triple replacement by SSA, FA, and GBS at 50% of total cement replacement, the compressive strength (Sc) of the blended cement mortars at 56 days was 93.7% and 92.9% of the co...

  13. The Evaluation of Material Properties of Low-pH Cement Grout for the Application of Cementitious Materials to Deep Radioactive Waste Repository Tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Seop; Kwon, S. K.; Cho, W. J.; Kim, G. W

    2009-12-15

    Considering the current construction technology and research status of deep repository tunnels for radioactive waste disposal, it is inevitable to use cementitious materials in spite of serious concern about their long-term environmental stability. Thus, it is an emerging task to develop low pH cementitious materials. This study reviews the state of the technology on low pH cements developed in Sweden, Switzerland, France, and Japan as well as in Finland which is constructing a real deep repository site for high-level radioactive waste disposal. Considering the physical and chemical stability of bentonite which acts as a buffer material, a low pH cement limits to pH {<=}11 and pozzolan-type admixtures are used to lower the pH of cement. To attain this pH requirement, silica fume, which is one of the most promising admixtures, should occupy at least 40 wt% of total dry materials in cement and the Ca/Si ratio should be maintained below 0.8 in cement. Additionally, selective super-plasticizer needs to be used because a high amount of water is demanded from the use of a large amount of silica fume. In this report, the state of the technology on application of cementitious materials to deep repository tunnels for radioactive waste disposal was analysed. And the material properties of low-pH and high-pH cement grouts were evaluated base on the grout recipes of ONKALO in Finlan.

  14. Properties of Cement Mortar Produced from Mixed Waste Materials with Pozzolanic Characteristics

    Science.gov (United States)

    Yen, Chi-Liang; Tseng, Dyi-Hwa; Wu, Yue-Ze

    2012-01-01

    Abstract Waste materials with pozzolanic characteristics, such as sewage sludge ash (SSA), coal combustion fly ash (FA), and granulated blast furnace slag (GBS), were reused as partial cement replacements for making cement mortar in this study. Experimental results revealed that with dual replacement of cement by SSA and GBS and triple replacement by SSA, FA, and GBS at 50% of total cement replacement, the compressive strength (Sc) of the blended cement mortars at 56 days was 93.7% and 92.9% of the control cement mortar, respectively. GBS had the highest strength activity index value and could produce large amounts of CaO to enhance the pozzolanic activity of SSA/FA and form calcium silicate hydrate gels to fill the capillary pores of the cement mortar. Consequently, the Sc development of cement mortar with GBS replacement was better than that without GBS, and the total pore volume of blended cement mortars with GBS/SSA replacement was less than that with FA/SSA replacement. In the cement mortar with modified SSA and GBS at 70% of total cement replacement, the Sc at 56 days was 92.4% of the control mortar. Modifying the content of calcium in SSA also increased its pozzolanic reaction. CaCl2 accelerated the pozzolanic activity of SSA better than lime did. Moreover, blending cement mortars with GBS/SSA replacement could generate more monosulfoaluminate to fill capillary pores. PMID:22783062

  15. Properties of Cement Mortar Produced from Mixed Waste Materials with Pozzolanic Characteristics.

    Science.gov (United States)

    Yen, Chi-Liang; Tseng, Dyi-Hwa; Wu, Yue-Ze

    2012-07-01

    Waste materials with pozzolanic characteristics, such as sewage sludge ash (SSA), coal combustion fly ash (FA), and granulated blast furnace slag (GBS), were reused as partial cement replacements for making cement mortar in this study. Experimental results revealed that with dual replacement of cement by SSA and GBS and triple replacement by SSA, FA, and GBS at 50% of total cement replacement, the compressive strength (Sc) of the blended cement mortars at 56 days was 93.7% and 92.9% of the control cement mortar, respectively. GBS had the highest strength activity index value and could produce large amounts of CaO to enhance the pozzolanic activity of SSA/FA and form calcium silicate hydrate gels to fill the capillary pores of the cement mortar. Consequently, the Sc development of cement mortar with GBS replacement was better than that without GBS, and the total pore volume of blended cement mortars with GBS/SSA replacement was less than that with FA/SSA replacement. In the cement mortar with modified SSA and GBS at 70% of total cement replacement, the Sc at 56 days was 92.4% of the control mortar. Modifying the content of calcium in SSA also increased its pozzolanic reaction. CaCl(2) accelerated the pozzolanic activity of SSA better than lime did. Moreover, blending cement mortars with GBS/SSA replacement could generate more monosulfoaluminate to fill capillary pores.

  16. Effect of Mineral Admixtures on Sulfate Attack Resistance of Cement-Based Materials%矿物掺合料改善水泥基材料抗硫酸盐侵蚀性能的微观分析

    Institute of Scientific and Technical Information of China (English)

    李华; 孙伟; 左晓宝

    2012-01-01

    采用CT、X射线衍射、扫描电子显微镜等测试方法,通过对不掺矿物掺合料以及掺30%粉煤灰或50%矿渣的水泥净浆、水泥砂浆在室温下5%Na2SO4溶液中浸泡2a后的宏观破坏形态和浆体组分及浆体形貌的分析,从微观层次上研究了矿物掺合料对水泥基材料抗硫酸盐侵蚀破坏的影响。结果表明:侵蚀后不掺矿物掺合料的试件由表及里呈现三层不同侵蚀状态,即表层石膏区、中层钙矾石区以及内层未侵蚀区。矿物掺合料的C3A含量稀释效应、火山灰反应以及微集料填充效应协同作用的结果使得试件的抗硫酸钠溶液侵蚀破坏性能显著提高。但矿渣中活性Al3+含量较高,能与SO42–反应生成大量钙矾石晶体,掺量不当会对试件的抗硫酸钠侵蚀性能不利。砂集料有阻碍微裂纹发展及增大试样内部不均匀性的相反作用,集料的含量、颗粒尺寸及分布对水泥基材料的抗硫酸钠侵蚀破坏性能的影响是以后研究中需关注的问题。%The appearance observation, mineral composition, as well ;as microstructure morphology towards various cement pastes and motars with and without 30% fly ash or 50% slag dipped in 5% Na2SO4 solution at room temperature for 2 years were characterized by X-CT, X-ray diffraction and scanning electron microscopy to investigate the effects of mineral admixtures such as slag and fly ash on the sulfate resistance performance of cement-based materials from the micro-level angle. The results show that the specimens without mineral admixtures appear three different attack states from surface to inside, i.e., the gypsum area, the ettringite area and the unaffected area. Mineral admixtures can improve the sulfate resistance performance of cement-based materials via synergy effect of reducing C3A content, pozzolanic reaction and micro-aggregates filling. However, the improper content of slag in cement-based mate- rials has a negative effect on

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-01-15

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

  18. Performance of the Cement Matrix Composite Material With Rubber Powder

    Institute of Scientific and Technical Information of China (English)

    SONG Shao-min; LIU Juan-hong; ZHANG Xi-qing

    2004-01-01

    The effect of the deferent rubber content substituted for fine aggregate on the mortar performancewas studied. The effects of the rubber coated with the coating materials on the mortar compressive strength, bendingstrength and impact work were discussed. The optimum rubber powder content and the suitable coating materialwere found. Through the electrical probe test- BEI, SEI and calcium ion distribution, and the slight crack and theinterface between the rubber and cement matrix are analyzed. The results show that the rubber powder coated withthe surface treatment materials A, B and C bas the capability of absorbing a large amount of energy under thecompressive and flexural load and the slight cracks of R- C were controlled and restrained.

  19. Secondary raw materials for synthesising new kind of cements

    Directory of Open Access Journals (Sweden)

    Goñi, S.

    2001-12-01

    Full Text Available The present paper is a comparative study of some characteristics of new belite cements obtained from two kind of wastes, which were used as secondary raw materials: fly ash (FA, of low CaO content, from coal combustion, and ash from incineration of municipal solid waste (MSWIA. Cements were synthesised in a range of temperature between 700°C and 900°C from MSWIA and FA, which were previously activated by hydrothermal treatment at 200°C The evolution of cemented phases with the heating temperature was followed by X-ray diffraction (XRD. The results were compared with those obtained from heating the starting FA and MSWIA without the previous hydrothermal treatment. The degree of hydration was quantitatively evaluated by the combined water content, determined from thermogravimetric analyses, during a period of 28 days or 200 days from mixing depending of hydration kinetics of each cement.

    Este trabajo es un estudio comparativo de algunas de las características de nuevos cementos belíticos, obtenidos a partir de dos tipos de residuos, como materia prima secundaria: cenizas volantes (CV de bajo contenido en cal, procedentes de la combustión del carbón y cenizas procedentes de la incineración de residuos sólidos urbanos (CIRSU. Los cementos fueron sintetizados en un rango de temperaturas comprendido entre 700°C y 900°C después de un tratamiento hidrotermal de la CV y CIRSU a 200°C La evolución de las fases cementicias, con la temperatura de calentamiento, fue estudiada por difracción de rayos X (DRX. Los resultados fueron comparados con aquellos obtenidos, directamente, por calentamiento de los residuos, sin un tratamiento hidrotermal previo de los mismos. El grado de hidratación fue cuantitativamente evaluado, por medio del análisis termogravimétrico, a partir del agua combinada de los cementos hidratados durante un período de 28 días o 200 días, dependiendo de la cinética de hidratación de cada cemento.

  20. [Endodontics in motion: new concepts, materials and techniques 1. Hydraulic Calcium Silicate Cements].

    Science.gov (United States)

    Moinzadeh, A T; Jongsma, L; de Groot-Kuin, D; Cristescu, R; Neirynck, N; Camilleri, J

    2015-01-01

    Hydraulic Calcium Silicate Cements (HCSCs) constitute a group of materials that have become increasingly popular in endodontics since the introduction of Mineral Trioxide Aggregate (MTA) in the 1990s. MTA is Portland cement to which bismuth oxide has been added to increase its radiopacity. The most important property of MTA is its capacity to set in water or a humid environment. However, MTA also has important limitations, for example, it's difficult to work with and can discolour teeth. Recently, numerous products based on HCSC chemistry, which can be considered as modifications of MTA intended to reduce its limitations, have become available on the market. Despite their potential advantages, all of these materials have their own specific limitations that are currently insufficiently known and investigated.

  1. Cement-based grouts in geological disposal of radioactive waste

    Energy Technology Data Exchange (ETDEWEB)

    Onofrei, M. [AECL Research, Pinnawa, Manitoba (Canada)

    1996-04-01

    The behavior and performance of a specially developed high-performance cement-based grout has been studied through a combined laboratory and in situ research program conducted under the auspices of the Canadian Nuclear Fuel Waste Management Program (CNFWMP). A new class of cement-based grouts - high-performance grouts-with the ability to penetrate and seal fine fractures was developed and investigated. These high-performance grouts, which were injected into fractures in the granitic rock at the Underground Research Laboratory (URL) in Canada, are shown to successfully reduce the hydraulic conductivity of the rock mass from <10{sup -7} m s{sup -1} to 10{sup -9} m s{sup -1} and to penetrate fissures in the rock with apertures as small as 10 {mu}m. Furthermore, the laboratory studies have shown that this high - performance grout has very low hydraulic conductivity and is highly leach resistant under repository conditions. Microcracks generated in this materials from shrinkage, overstressing or thermal loads are likely to self-seal. The results of these studies suggest that the high-performance grouts can be considered as viable materials in disposal-vault sealing applications. Further work is needed to fully justify extrapolation of the results of the laboratory studies to time scales relevant to performance assessment.

  2. 矿物掺合料对硫铝酸盐水泥基灌浆料性能的影响%Effect of mineral admixtures on performance of grout material based on sulphate aluminium cement

    Institute of Scientific and Technical Information of China (English)

    戴民; 赵慧

    2014-01-01

    为研究矿物掺合料对硫铝酸盐水泥基灌浆料力学性能及流动性能的影响,分别以硅灰、双飞粉、轻质碳酸钙为掺合料制备了硫铝酸盐水泥基灌浆料。在不同水胶比条件下,测试了灌浆料的流动度及不同龄期的抗折、抗压强度。试验结果表明:加入一定量硅灰可以提高灌浆料各龄期强度,但随着硅灰掺量增大,灌浆料流动度降低;加入一定量双飞粉对灌浆料流动度及各龄期强度均有负面影响;加入一定量轻质碳酸钙对灌浆料不同龄期抗压强度有所提高,对流动度及抗折强度没有明显影响。%In order to study mineral admixtures' impact on the mechanical and flow properties of sulfur aluminate cement-based grouting material,the author produces sulfur aluminate cement-based grouting material samples by useing silica fume ,Flying powder and light cal-cium carbonate as mineral admixtures.The author also tests and analysises fluidity ,strength index in different water cement ratio. The fl-lowing are the results that we can conclude:(1)adding a certain amount of silica fume can improve the strength of grouting material in each stage,while the grout fluidity will reduce when the dosage of silica fume increases;(2)adding a certain amount of flying powder has negative effects on the grout fluidity and the strength in each stage;(3)adding a certain amount of light calcium carbonate can improve the compressive strength of grout in ecah stage,while has no obvious effects on fluidity and flexural strength.

  3. Base Course Modification through Stabilization using Cement and Bitumen

    Directory of Open Access Journals (Sweden)

    S. M. Marandi

    2009-01-01

    Full Text Available The main objectives of this research was to analyze the use of combined cement and bitumen emulsion in base course stabilization in details and examine its replacement with conventional pavement in regions with low quality materials and limited construction period. To conduct the objectives, the research divided into three phases. Phase I involved the optimization of cement and bitumen emulsion. In this case, a series of Indirect Tensile Strength (ITS, Unconfined Compressive Strength (UCS and Marshal Tests carried out. In the second phase, various alternative roadway sections examined for minimizing the pavement thickness and increasing the bearing capacity and finally in third phase, a Falling Weight Deflectometer (FWD machine used to examine the pavement bearing capacity for three sections of the roadway. It was found that, the optimum values to eliminate the creation of shrinkage cracks in the whole project and minimize the execution period and construction costs were 3% for both binders in stabilization and its replacement with conventional pavement method (i.e., stabilized layer with conventional sub-base and base layers. Also, FWD results showed that, the bearing capacity of the constructed pavement using stabilization method is far beyond the predicted values in pavement design. Furthermore, it was found that, with high inflation rate and political situation in the region, base stabilized method decreased the final roadway construction costs in compare with conventional pavement method.

  4. The Impact of Coal Combustion Fly Ash Used as a Supplemental Cementitious Material on the Leaching of Constituents from Cements and Concretes

    Science.gov (United States)

    The objective of this report is to compare the leaching of portland cement-based materials that have been prepared with and without coal combustion fly ash to illustrate whether there is evidence that the use of fly ash in cement and concrete products may result in increased leac...

  5. Action Course and Mechanism of Shrinkage Reducing Admixture in Cement Based Materials%减缩剂在水泥基材料中的作用历程与机理研究

    Institute of Scientific and Technical Information of China (English)

    王智; 郭清春; 江楠; 钱觉时; 党玉栋

    2012-01-01

    研究了2种减缩剂被水泥熟料、矿渣和粉煤灰等固体颗粒吸附的性质及其对水溶液和模拟水泥石孔隙溶液表面张力、蒸发速率的影响.结果表明:水泥熟料、矿渣和粉煤灰等固体颗粒对2种减缩剂的平均吸附率小于10%,有90%以上减缩剂溶于溶液中;2种减缩剂溶于水或模拟水泥石孔隙溶液中均能有效降低溶液的表面张力和蒸发速率.减缩剂的作用历程和机理为:溶解于水泥石孔隙溶液中的减缩剂能长期稳定地降低溶液的表面张力,从而减少因毛细孔失水所产生的收缩应力,此外还能在一定程度上降低溶液的蒸发速率,这两方面的共同作用抑制了水泥基材料的收缩.%The adsorption of two shrinkage reducing admixtures(SRAs) on the surface of solid particles, such as cement clinker, slag and fly ash were investigated. Besides, the effect of SRA on surface tension and evaporation rate of water solution and simulated pore solution(SPS) were researched as well. The results indicate that the average adsorption rate of SRA on the surface of solid particles is less than 10% , so more than 90% of SRA remains in solution. The SRAs can significantly reduce the surface tension and e-vaporation of water solution and SPS. The action course and mechanism of SRA can be considered as the fact that the shrinkage reduction of cement based materials is resulted from the dissolution of SRA in the pore solution leading to significant reduction of surface tension of pore solution. Meanwhile, the SRA lowers the evaporation rate of the solution. These two effects may be the main causes of shrinkage reduction of cement based materials.

  6. Properties of lightweight cement-based composites containing waste polypropylene

    Science.gov (United States)

    Záleská, Martina; Pavlíková, Milena; Pavlík, Zbyšek

    2016-07-01

    Improvement of buildings thermal stability represents an increasingly important trend of the construction industry. This work aims to study the possible use of two types of waste polypropylene (PP) for the development of lightweight cement-based composites with enhanced thermal insulation function. Crushed PP waste originating from the PP tubes production is used for the partial replacement of silica sand by 10, 20, 30, 40 and 50 mass%, whereas a reference mixture without plastic waste is studied as well. First, basic physical and thermal properties of granular PP random copolymer (PPR) and glass fiber reinforced PP (PPGF) aggregate are studied. For the developed composite mixtures, basic physical, mechanical, heat transport and storage properties are accessed. The obtained results show that the composites with incorporated PP aggregate exhibit an improved thermal insulation properties and acceptable mechanical resistivity. This new composite materials with enhanced thermal insulation function are found to be promising materials for buildings subsoil or floor structures.

  7. Distribution of Hg, As and Se in material and flue gas streams from preheater-precalciner cement kilns and vertical shaft cement kilns in China.

    Science.gov (United States)

    Yan, Dahai; Peng, Zheng; Ding, Qiong; Karstensen, Kåre Helge; Engelsen, Christian J; Li, Li; Ren, Yong; Jiang, Chen

    2015-08-01

    The aim of this study was to evaluate the behavior of Hg, As, and Se in cement production. Two types of cement plants were studied, including the vertical shaft kiln (VSK) and preheater-precalciner kiln (PPK) processes. Determination of Hg, As, and Se in the main material and gas streams were performed. It was found that recycling of particulate matter captured by an air pollution control device caused a significant enrichment of Hg and As inside both processes. The total quantity of Hg entering the process and the quantity emitted to the atmosphere were found to be 10-109 and 6.3-38 mg, respectively, per ton of clinker produced. The average Hg emission was calculated to be around 41% of the total mercury input. The emissions found complied with the European Union (EU) limit and exceeded partly the U.S. limit. Furthermore, it was found that oxidized mercury was the dominant species in the PPK process, whereas the reduced form was dominant in the VSK process, due to the oxidizing and reducing gas conditions, respectively. Regarding the distribution of As and Se, the major amounts were bound to the solid materials, that is, cement clinker and particulate matter. Based on cement production data in China in 2013, the annual emissions of Hg and As were estimated to be in the range of 8.6-52 and 4.1-9.5 tons, respectively.

  8. Cytotoxicity and Osteogenic Potential of Silicate Calcium Cements as Potential Protective Materials for Pulpal Revascularization

    Science.gov (United States)

    Bortoluzzi, Eduardo A.; Niu, Li-na; Palani, Chithra D.; El-Awady, Ahmed R.; Hammond, Barry D.; Pei, Dan-dan; Tian, Fu-cong; Cutler, Christopher W.; Pashley, David H.; Tay, Franklin R.

    2016-01-01

    Objectives In pulpal revascularization, a protective material is placed coronal to the blood clot to prevent recontamination and to facilitate osteogenic differentiation of mesenchynal stem cells to produce new dental tissues. Although mineral trioxide aggregate (MTA) has been the material of choice for clot protection, it is easily displaced into the clot during condensation. The present study evaluated the effects of recently-introduced calcium silicate cements (Biodentine and TheraCal LC) on the viability and osteogenic differentiation of human dental pulp stem cells (hDPSCs) by comparing with MTA Angelus. Methods Cell viability was assessed using XTT assay and flow cytometry. The osteogenic potential of hDPSCs exposed to calcium silicate cements was examined using qRT-PCR for osteogeic gene expressions, alkaline phosphatase enzyme activity, Alizarin red S staining and transmission electron microscopy of extracellular calcium deposits. Parametric statistical methods were employed for analyses of significant difference among groups, with α=0.05. Results The cytotoxic effects of Biodentine and TheraCal LC on hDPSCs were time- and concentration-dependent. Osteogenic differentiation of hDPSCs was enhanced after exposure to Biodentine that was depleted of its cytotoxic components. This effect was less readily observed in hDPSCs exposed to TheraCal LC, although both cements supported extracelluar mineralization better than the positive control (zinc oxide-eugenol–based cement). Significance A favorable tissue response is anticipated to occur with the use of Biodentine as a blood clot-protecting material for pulpal revascularizaiton. Further investigations with the use of in vivo animal models are required to validate the potential adverse biological effects of TheraCal LC on hDPSCs. PMID:26494267

  9. 高炉矿渣基充填胶凝材料的制备与应用%Preparation and Application Performance of Cementation Material Based on Blast Furnace Slag

    Institute of Scientific and Technical Information of China (English)

    赵鹏凯; 赵亮; 景娇燕

    2013-01-01

    以高炉矿渣为主要原料,用石灰作激活剂,硬石膏、氯化钙作早强剂,通过试验制备一种高炉矿渣基胶凝材料。以铁尾矿、粉煤灰和河砂为骨料,用所制备的胶凝材料和普硅水泥作胶结料进行不同浓度砂浆的应用性能试验。试验表明:相同条件下,试验制备的高炉矿渣基胶凝材料能完全代替水泥用于矿山生产,并具有生产成本低,节能降耗的优点。%In this paper, one new cementation material has been prepared using the blast-furnace slag (BFS) as the main material, lime as activator, anhydrite and calcium chloride as early strength agent, and iron tailings, fly ash and sand as aggregate. The application performance of new material and ordinary Portland cement has been compared using them as binder in mortars with different concentration. The result showed that under the same conditions, the prepared blast-furnace slag cementation material can completely replace cement in mine backfilling, and has the advantages of low cost, saving energy and reducing consumption.

  10. High-temperature cementing materials for completion of geothermal wells. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kalyoncu, R.S.; Snyder, M.J.

    1981-05-01

    Several portland cement types, oil well cements, and various additives and admixtures were evaluated during the course of development of a number of promising compositions suitable for geothermal applications. Among the cements and various materials considered were portland cement Types I, III, and V; oil well cement Classes G, H, and J; and additives such as silica flour, blast furnace slags, pozzolan, hydrated lime, perlite, and aluminum phosphate. Properties of interest in the study were thickening time, compressive strength, cement-to-metal bond strength, and effects of the cements on the corrosion of steel well casings. Testing procedures and property data obtained on a number of compositions are presented and discussed. Several cementing compositions comprised of Class J oil well cement, pozzolan, blast furnace slags, and silica flour were found to possess properties which appear to make them suitable for use in geothermal well completions. Five of the promising cementing compositions have been submitted to the National Bureau of Standards for additional testing.

  11. Chromium speciation in hazardous, cement-based waste forms

    Science.gov (United States)

    Lee, J. F.; Bajt, S.; Clark, S. B.; Lamble, G. M.; Langton, C. A.; Oji, L.

    1995-02-01

    XANES and EXAFS techniques were used to determine the oxidation states and local structural environment of Cr in cement-based waste forms. Results show that Cr in untreated Portland cement formulations remains as toxic Cr 6+, while slag additives to the cement reduce Cr 6+ to the less toxic, less mobile Cr 3+ species. EXAFS analysis suggests that the Cr 6+ species is surrounded by four nearest oxygen atoms, while the reduced Cr 3+ sp ecies is surrounded by six oxygen atoms. The fitted CrO bond lengths for Cr 6+ and Cr 3+ species are around 1.66 and 1.98 Å, respectively.

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

    Science.gov (United States)

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

    2014-01-01

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

  13. The Influence of Flying Ash's Loss on Press-Sensitivity for Smart Cement-Based Materials%粉煤灰烧失量对机敏水泥基材料压敏性影响

    Institute of Scientific and Technical Information of China (English)

    姚嵘; 王栋民

    2009-01-01

    To reach the effective utilization of flying ash with high loss,two flying ashes with ash loss of 4.88% and 26.28% in mass were added at the dosage of 15% ,20% and 25% to smart cement-based materials containing 0.5% or 0.9% of carbon fibers. The investigation of press-sensitivity and conductivity under circulating small stress shows that with increasing flying ash dosage, the press-sensitivity of smart cement-based mortar decreased for lower fiber content but increased for higher fiber content,and the mortar with high loss flying ash was lower in conductivity than that with low loss flying ash.%为探讨高烧失量粉煤灰的利用,在碳纤维质量分数为0.5%和0.9%的机敏水泥基材料中,分别加入烧失量(质量分数)4.88%和26.28%,掺量15%,20%,25%的两种粉煤灰.通过对其在小应力循环作用下压敏性和导电性变化规律的研究,指出当纤维掺量较低时,含高烧失量粉煤灰的机敏水泥砂浆的压敏性,随着粉煤灰量的增加而变差;当纤维掺量较高时,含高烧失量粉煤灰的机敏水泥砂浆的压敏性,随着粉煤灰量的增加而变好;含高烧失量粉煤灰的机敏水泥砂浆导电性总低于含低烧失量粉煤灰的水泥砂浆.

  14. Secondary fuels and raw materials in the Spanish cement industry

    Energy Technology Data Exchange (ETDEWEB)

    Gordobil, J.C.U.; Guede, Elena [Cementos Lemona s.a. (Spain)

    1997-03-01

    The growing environmental and energy concern are having an impact on the Spanish cement industry. This article describes the impact on waste management, the operation of cement kilns and the possibility for recycling. Current projects and future prospects are described. (UK)

  15. Fire experience temperature detected experiment of ecological cement-based composite material%轻质水泥基结构火灾经历温度的红外热像检测实验

    Institute of Scientific and Technical Information of China (English)

    王海蓉; 陈振中; 梁栋

    2011-01-01

    以轻质水泥基结构为研究对象,利用红外热像和多通路温度传感器检测材料在火灾中经历的最高温度.在红外热像温升随时间的变化关系的基础上,建立了轻质水泥基材料的红外热像平均温升与其受火温度及强度损失的回归方程,得到该结构的火灾损伤的检测和评估模型.结果表明:(1)作为含有气泡状有机质的新型建筑材料,其高温作用后的红外热像温升明显较混凝土结构高;(2)材料的受火温度和材料强度损失的检测模型分别为:T=472.734 458x-587.909 642和f(T)/f0=110.662 138-0.154 507x;(3)通过红外热像检测模型,可评估火灾后的轻质水泥基材料的损伤程度,获得结构破坏前兆信息.%Ecological lightweight cement-based structure was studied , using infrared thermal imaging and inclusions burst the maximum temperature of the material experienced by the fire was detected.Based on Infrared thermal imaging in the variation of temperature over time, average temperature rise of Infrared thermal imaging with fire temperature and intensity loss by the regression equation was established, the structure of the fire damage detection and evaluation model was found.The results showed that: (1) As a new type of building materials with bubble-like organic matter, the infrared thermal imaging temperature significantly higher than the concrete structure , after high temperature ; (2) burst temperature and Infrared thermal imaging test was basically the same; (3) through the infrared thermal image detection model, the damage of ecological lightweight cement-based composite material after fire could be evaluated, precursor information of broken ring structure would be get.

  16. Developing improved relationships between microstructure and creep and shrinkage of cement-based materials. Final report for the period September 9, 1998 - July 31, 2000

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, Hamlin M.

    2001-01-01

    The shrinkage of concrete that occurs on drying is a complex function of age of concrete, rate of drying, temperature, and composition of concrete. This project investigated the fundamental relationships between microstructure and shrinkage. In order to accomplish this goal a new quantitative image analysis technique was developed to analyze the distribution of strain throughout the microstructure during drying. The technique has been verified at NIST and the results have provided new insights. A major result of this effort has been the redefinition of microstructure of cement paste. Large deformations, both expansive and compressive, occur throughout the microstructure. These large deformations can be best explained by considering the calcium silicate phase to be a colloid. A new model for calcium silicate hydrate was developed.

  17. 磷酸镁水泥的研究与应用进展%Review of Magnesia-phosphate Cement Based Materials

    Institute of Scientific and Technical Information of China (English)

    刘凯; 李东旭

    2011-01-01

    论述了磷酸锾水泥的一些研究进展,包括磷酸镁水泥的水化机理、水化产物、性能及其影响因素等,着重综述了磷酸镁水泥的耐久性问题和改性研究,在此基础上探讨了磷酸镁水泥的应用前景.%The development of magnesium-phosphate cement in recent decades is reviewed, including hydration mechanisms, hydrates, properties and related influencing factors. Herein, durability and modification study are especially emphasized. On the basis of these aspects, application prospects are dicussed.

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

    Science.gov (United States)

    Özgüner, A. M.

    2014-09-01

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

  19. Physico-mechanical and physico-chemical properties of synthesized cement based on plasma- and wet technologies

    Science.gov (United States)

    Sazonova, Natalya; Skripnikova, Nelli

    2016-01-01

    In this work we studied the influence of plasma-chemical technology of cement clinker synthesis under conditions of high-concentrated heat streams on the properties of cement on fixing such factors as raw-material type (chemical and mineralogical composition), fraction composition, homogenization and module characters of the raw-material mixture. In this connection the sludge of the cement plant in town Angarsk, based on which the cement clinker synthesis using the wet- and plasma-chemical technologies was performed, was used in the studies. The results of chemical X-ray-phase analysis, petrography of cement clinkers, differential scanning colorimetry of hardened cement paste are represented in this work. The analysis of building-technical properties of inorganic viscous substances was performed. It was found that in using the identical raw-material mixture the cement produced with temperature higher by 1650 °C than the traditional one may indicate the higher activity. The hardened cement paste compressive strength at the age of 28 days was higher than the strength of the reference samples by 40.8-41.4 %.

  20. Heuristic economic assessment of the Afghanistan construction materials sector: cement and dimension stone production

    Science.gov (United States)

    Mossotti, Victor G.

    2014-01-01

    Over the past decade, the U.S. Government has invested more than $106 billion for physical, societal, and governmental reconstruction assistance to Afghanistan (Special Inspector General for Afghanistan Reconstruction, 2012a). This funding, along with private investment, has stimulated a growing demand for particular industrial minerals and construction materials. In support of this effort, the U.S. Geological Survey released a preliminary mineral assessment in 2007 on selected Afghan nonfuel minerals (Peters and others, 2007). More recently, the 2007 mineral assessment was updated with the inclusion of a more extensive array of Afghan nonfuel minerals (Peters and others, 2011). As a follow-up on the 2011 assessment, this report provides an analysis of the current use and prospects of the following Afghan industrial minerals required to manufacture construction materials: clays of various types, bauxite, gypsum, cement-grade limestone, aggregate (sand and gravel), and dimension stone (sandstone, quartzite, granite, slate, limestone, travertine, marble). The intention of this paper is to assess the: Use of Afghan industrial minerals to manufacture construction materials, Prospects for growth in domestic construction materials production sectors, Factors controlling the competitiveness of domestic production relative to foreign imports of construction materials, and Feasibility of using natural gas as the prime source of thermal energy and for generating electrical energy for cement production. The discussion here is based on classical principles of supply and demand. Imbedded in these principles is an understanding that the attributes of supply and demand are highly variable. For construction materials, demand for a given product may depend on seasons of the year, location of construction sites, product delivery time, political factors, governmental regulations, cultural issues, price, and how essential a given product might be to the buyer. Moreover, failure on the

  1. Cement industry control system based on multi agent

    Institute of Scientific and Technical Information of China (English)

    王海东; 邱冠周; 黄圣生

    2004-01-01

    Cement production is characterized by its great capacity, long-time delay, multi variables, difficult measurement and muhi disturbances. According to the distributed intelligent control strategy based on the multi agent, the multi agent control system of cement production is built, which includes integrated optimal control and diagnosis control. The distributed and multiple level structure of multi agent system for the cement control is studied. The optimal agent is in the distributed state, which aims at the partial process of the cement production, and forms the optimal layer. The diagnosis agent located on the diagnosis layer is the diagnosis unit which aims at the whole process of the cement production, and the central management unit of the system. The system cooperation is realized by the communication among optimal agents and diagnosis agent. The architecture of the optimal agent and the diagnosis agent are designed. The detailed functions of the optimal agent and the diagnosis agent are analyzed.At last the realization methods of the agents are given, and the application of the multi agent control system is presented. The multi agent system has been successfully applied to the off-line control of one cement plant with capacity of 5 000 t/d. The results show that the average yield of the clinker increases 9.3% and the coal consumption decreases 7.5 kg/t.

  2. Novel bioactive composite bone cements based on the beta-tricalcium phosphate-monocalcium phosphate monohydrate composite cement system.

    Science.gov (United States)

    Huan, Zhiguang; Chang, Jiang

    2009-05-01

    Bioactive composite bone cements were obtained by incorporation of tricalcium silicate (Ca3SiO5, C3S) into a brushite bone cement composed of beta-tricalcium phosphate [beta-Ca3(PO4)2, beta-TCP] and monocalcium phosphate monohydrate [Ca(H2PO4)2.H2O, MCPM], and the properties of the new cements were studied and compared with pure brushite cement. The results indicated that the injectability, setting time and short- and long-term mechanical strength of the material are higher than those of pure brushite cement, and the compressive strength of the TCP/MCPM/C3S composite paste increased with increasing aging time. Moreover, the TCP/MCPM/C3S specimens showed significantly improved in vitro bioactivity in simulated body fluid and similar degradability in phosphate-buffered saline as compared with brushite cement. Additionally, the reacted TCP/MCPM/C3S paste possesses the ability to stimulate osteoblast proliferation and promote osteoblastic differentiation of the bone marrow stromal cells. The results indicated that the TCP/MCPM/C3S cements may be used as a bioactive material for bone regeneration, and might have significant clinical advantage over the traditional beta-TCP/MCPM brushite cement.

  3. Self-healing of early age cracks in cement-based materials based on mineralization of microorganism%基于微生物矿化技术的水泥基材料早期裂缝自修复

    Institute of Scientific and Technical Information of China (English)

    陈怀成; 钱春香; 任立夫

    2016-01-01

    To improve the self-repairing effect of early age cracks in cement-based materials,one type of microorganism which can produce carbonic anhydrase is adopted.The method of water seep-age and image processing technology are used to characterize the crack healing efficiency at different crack widths and different cracking ages of cement paste.The mineral composition of deposit sedi-ment in cracks is analyzed by ways of X-ray diffraction (XRD),scanning electron microscope (SEM)and energy dispersion spectrum (EDS).The CaCO3 precipitated depth in the cracks is also studied by the Photoshop.The experimental results indicate that cracks below 0.5 mm was almost completely closed at early age of 7 d,and the repair ability of microbial self-healing agent was limit-ed for cracks with width between 0.5 and 0.8 mm,and cracks with width up to 0.8 mm was diffi-cult to be repaired.The self-healing agent showed a good repair effect at early age of 7 d,and the longer the cracking age,the more difficult to repair.XRD analysis shows that the precipitant in cracks was calcite calcium carbonat.The depositing depth of CaCO3 in cracks measured by the standard tools of Photoshop decreased with the increase of crack width.%为了提高水泥基材料早期裂缝的自修复效果,采用了一种具有矿化作用的碳酸酐酶微生物.利用渗水法和图像处理技术研究了该微生物修复剂对不同裂缝宽度、不同开裂龄期下水泥净浆裂缝的修复情况.同时通过 XRD,SEM 和 EDS 技术对裂缝沉积物进行成分分析,并结合 Pho-toshop 软件研究了裂缝处矿化 CaCO3的沉积量.研究结果表明:开裂龄期为7 d 时,宽度在0.5 mm 以下的裂缝很快修复完全,0.5~0.8 mm 的裂缝修复受到一定限制,0.8 mm 以上的裂缝较难修复完全;开裂龄期为7 d 时,该自修复剂具有良好的修复效果,但开裂龄期越长,越难以修复;通过 XRD 分析确定了产物为方解石型 CaCO3

  4. ETV Program Report: Coatings for Wastewater Collection Systems - Standard Cement Materials, Epoxy Coating 4553

    Science.gov (United States)

    The Standard Cement Materials, Inc. Standard Epoxy Coating 4553™ (SEC 4553) epoxy coating used for wastewater collection system rehabilitation was evaluated by EPA’s Environmental Technology Verification Program under laboratory conditions at the Center for Innovative Grouting Ma...

  5. High-Temperature Release of SO2 from Calcined Cement Raw Materials

    DEFF Research Database (Denmark)

    Nielsen, Anders Rooma; Larsen, Morten B.; Glarborg, Peter

    2011-01-01

    During combustion of alternative fuels in the material inlet end of cement rotary kilns, local reducing conditions may occur and cause reductive decomposition of sulfates from calcined cement raw materials. Decomposition of sulfates is problematic because it increases the gas-phase SO2...... concentration, which may cause deposit formation in the kiln system. In this study, the release of sulfur from calcined cement raw materials under both oxidizing and reducing conditions is investigated. The investigations include thermodynamic equilibrium calculations in the temperature interval of 800–1500 °C...... and experiments in a tube furnace reactor in the temperature interval of 900–1100 °C. The investigated conditions resemble actual conditions in the material inlet end of cement rotary kilns. It was found that the sulfates CaSO4, K2SO4, and Na2SO4 were all stable under oxidizing conditions but began to decompose...

  6. Correlation between the degree of conversion and the elution of leachable components from dental resin-based cements

    Directory of Open Access Journals (Sweden)

    KOSOVKA OBRADOVIĆ-DJURIČIĆ

    2011-09-01

    Full Text Available This study examined the possible correlation between the degree of conversion (DC and the amount of substances eluted from three commercial cured resin-based cements. The DC of the various resin-based cements was measured by Raman spectroscopy, while the quantity of unreacted monomers released from the cement matrix (triethylene glycol dimethacrylate, TEGDMA, urethane dimethacrylate, UDMA, 2-hydroxyethyl methacrylate, HEMA and bisphenol A was determined by high pressure liquid chromatography (HPLC. The obtained results, after multiple statistical evaluation (one way ANOVA, LSD post hoc test, showed no significant differences in the DC values between the resin cements. On the contrary, the results of the HPLC analysis depicted statistically significant differences between the three materials with respect to the amount of leached monomers. In addition, no correlation between the DC and the amount of eluted substances from the tested cured composite cements was found.

  7. Improved Encapsulation Method of Sensing Element for Cement-Based Piezoelectric Sensor

    Institute of Scientific and Technical Information of China (English)

    YANG Xiaoming; LI Zongjin; LI Zhongxian

    2006-01-01

    An improved encapsulation method of a sensing element for a cement-based piezoelectric sensor used in civil engineering structure was developed and some tests were carried out for validating this method. The cement-based piezoelectric sensor of this kind is mainly used in concrete structure due to its compatibility with concrete, and the encapsulation method of its sensing element is important to the effectiveness and accuracy of the transfer of the stress from concrete to the sensing element. The sensor's measurement error of the previous encapsulation method, which was induced by the area of the encapsulation material and the inherent difference of Young's modulus between cement and encapsulation material, was analyzed theoretically using parallel model. In the improved method, the error is minimized by decreasing the area of the encapsulation material and changing the configuration of the cement and piezoelectric material in the sensor. Two sensors made by the previous and improved methods were embedded in two prisms respectively and the prisms were compressed on Material Test System. Through the comparison of the measurement errors of the two sensors, the improved method was evaluated. The test results show that the improved encapsulation method is effective and feasible.

  8. Optimization of fly ash as sand replacement materials (SRM) in cement composites containing coconut fiber

    Science.gov (United States)

    Nadzri, N. I. M.; Jamaludin, S. B.; Mazlee, M. N.; Jamal, Z. A. Z.

    2016-07-01

    The need of utilizing industrial and agricultural wastes is very important to maintain sustainability. These wastes are often incorporated with cement composites to improve performances in term of physical and mechanical properties. This study presents the results of the investigation of the response of cement composites containing coconut fiber as reinforcement and fly ash use as substitution of sand at different hardening days. Hardening periods of time (7, 14 and 28 days) were selected to study the properties of cement composites. Optimization result showed that 20 wt. % of fly ash (FA) is a suitable material for sand replacement (SRM). Meanwhile 14 days of hardening period gave highest compressive strength (70.12 MPa) from the cement composite containing 9 wt. % of coconut fiber and fly ash. This strength was comparable with the cement without coconut fiber (74.19 MPa) after 28 days of curing.

  9. Strengthening of Concrete Structures with cement based bonded composites

    DEFF Research Database (Denmark)

    Täljsten, Björn; Blanksvärd, Thomas

    2008-01-01

    Polymers). The method is very efficient and has achieved world wide attention. However, there are some drawbacks with the use of epoxy, e.g. working environment, compatibility and permeability. Substituting the epoxy adherent with a cement based bonding agent will render a strengthening system...... with improved working environment and better compatibility to the base concrete structure. This study gives an overview of different cement based systems, all with very promising results for structural upgrading. Studied parameters are structural retrofit for bending, shear and confinement. It is concluded...

  10. Micro-mechanism Analysis on Cement-based Materials with Fly Ash and PVA Fiber%粉煤灰和PVA纤维复掺水泥基材料微观机理分析

    Institute of Scientific and Technical Information of China (English)

    何芸; 何真; 孙海燕

    2014-01-01

    目前关于粉煤灰对PVA纤维与基体间粘结界面,以及对直接拉伸和韧性的影响研究还较少,通过采用PVA纤维、粉煤灰两种材料复掺,研究制备出一类具有超高抗拉韧性和优异裂缝无害化分散能力的纤维增韧水泥基材料。采用扫描电镜从微观机理上对其增韧机理进行了深入剖析,研究结果表明,采用纤维与粉煤灰复掺的方式,既能控制好纤维与基体界面之间的特征参数即化学粘结强度和摩擦粘结强度,保证硬化水泥石具有良好的化学粘结强度,同时又利用粉煤灰的颗粒微珠效应使其不至过高,从而使滑移-硬化效应更好地得以发挥。%At present ,there’s only a few research of the influences of adding fly ash on the bonding interface between PVA fiber and matrix as well as the direct tensile and toughness .Accordingly ,a toughness-enhanced cement-based mate-rial was developed by mixing PVA fiber and fly ash .This material possesses excellent properties of ultra-high tensile toughness and dispersive capacity of anti-crack treatment .SEM was adopted to analyse the toughness-enhancing property of PVA fiber from the perspective of micromechanism .The results indicate that by adding PVA fiber and fly ash ,the pa-rameters of bond strength between fiber and matrix ,which are chemical bond strength and friction bond strength ,can be well controlled ,thus the hardened set cement is given excellent chemical bond strength ,which is controlled from exceed-ing a certain level by the microsphere effect of the fly ash .This will give full play in effect of sliding and strain hardening of PVA fiber .

  11. Research on preparation and properties of marine magnesium phosphate cement based materials%海工磷酸镁水泥基材料的制备及性能研究

    Institute of Scientific and Technical Information of China (English)

    蒋江波; 薛明; 汪宏涛; 曹巨辉

    2012-01-01

    We prepared marine magnesium phosphate cement(MPC) based materials by using sea water and sand,then researched the storage performance,the early strength characteristics and the anti-sea erosion performance of this materials.Results show that the magnesium phosphate cement has good storage performance,after the raw materials was stored with certain storage method for 360d,the strength of MPC was decreased less than 5%,and after the raw materials was stored for 1000d,the strength of MPC was decreased less than 10%.The compressive strength of this marine MPC based materials hydrating for 2h was more than 28MPa,the compressive strength of this marine MPC based materials hydrating for 1d had reached more than 52MPa and the setting time was less than 25min.The marine MPC mortar we prepared has good performance against sea erosion.%选用海砂、海水制备了海工磷酸镁水泥基材料,研究了该材料的贮存性能,早期强度特性及抗海水侵蚀性能。结果显示磷酸镁水泥有着良好的贮存性能,原材料按一定方式存放360d后,水泥强度降低不超过5%,原材料存放1000d后,水泥强度降低不超过10%;所制备的海工磷酸镁水泥基材料,2h的抗压强度均达到28MPa以上,1d抗压强度已达52MPa以上,凝结时间在25min以内;所制备的海工磷酸镁水泥胶砂抗海水侵蚀性能良好。

  12. Strain sensitivity of carbon nanotube cement-based composites for structural health monitoring

    Science.gov (United States)

    D'Alessandro, Antonella; Ubertini, Filippo; Laflamme, Simon; Rallini, Marco; Materazzi, Annibale L.; Kenny, Josè M.

    2016-04-01

    Cement-based smart sensors appear particularly suitable for monitoring applications, due to their self-sensing abilities, their ease of use, and their numerous possible field applications. The addition of conductive carbon nanofillers into a cementitious matrix provides the material with piezoresistive characteristics and enhanced sensitivity to mechanical alterations. The strain-sensing ability is achieved by correlating the variation of external loads or deformations with the variation of specific electrical parameters, such as the electrical resistance. Among conductive nanofillers, carbon nanotubes (CNTs) have shown promise for the fabrication of self-monitoring composites. However, some issues related to the filler dispersion and the mix design of cementitious nanoadded materials need to be further investigated. For instance, a small difference in the added quantity of a specific nanofiller in a cement-matrix composite can substantially change the quality of the dispersion and the strain sensitivity of the resulting material. The present research focuses on the strain sensitivity of concrete, mortar and cement paste sensors fabricated with different amounts of carbon nanotube inclusions. The aim of the work is to investigate the quality of dispersion of the CNTs in the aqueous solutions, the physical properties of the fresh mixtures, the electromechanical properties of the hardened materials, and the sensing properties of the obtained transducers. Results show that cement-based sensors with CNT inclusions, if properly implemented, can be favorably applied to structural health monitoring.

  13. High-volume use of self-cementing spray dry absorber material for structural applications

    Science.gov (United States)

    Riley, Charles E.

    Spray dry absorber (SDA) material, or spray dryer ash, is a byproduct of energy generation by coal combustion and sulfur emissions controls. Like any resource, it ought to be used to its fullest potential offsetting as many of the negative environmental impacts of coal combustion as possible throughout its lifecycle. Its cementitious and pozzolanic properties suggest it be used to augment or replace another energy and emissions intensive product: Portland cement. There is excellent potential for spray dryer ash to be used beneficially in structural applications, which will offset CO2 emissions due to Portland cement production, divert landfill waste by further utilizing a plentiful coal combustion by-product, and create more durable and sustainable structures. The research into beneficial use applications for SDA material is relatively undeveloped and the material is highly underutilized. This dissertation explored a specific self-cementing spray dryer ash for use as a binder in structural materials. Strength and stiffness properties of hydrated spray dryer ash mortars were improved by chemical activation with Portland cement and reinforcement with polymer fibers from automobile tire recycling. Portland cement at additions of five percent of the cementitious material was found to function effectively as an activating agent for spray dryer ash and had a significant impact on the hardened properties. The recycled polymer fibers improved the ductility and toughness of the material in all cases and increased the compressive strength of weak matrix materials like the pure hydrated ash. The resulting hardened materials exhibited useful properties that were sufficient to suggest that they be used in structural applications such as concrete, masonry block, or as a hydraulic cement binder. While the long-term performance characteristics remain to be investigated, from an embodied-energy and carbon emissions standpoint the material investigated here is far superior to

  14. Improving the connection between wood and cement using LBL nanocoating to create a lightweight, eco-friendly structural material

    Science.gov (United States)

    Bejo, L.; Major, B.; Csoka, L.; Hantos, Z.; Karacsonyi, Zs

    2016-04-01

    Structural elements made out of cement bonded wood may be an excellent alternative to flammable organic bonded composite beams, and CO2 intensive, heavy and nonrenewable reinforced concrete. Unfortunately, preliminary studies showed that a sufficient load-bearing performance is difficult to achieve. Improving the compatibility of cement and wood by LbL nanocoating may be a significant step towards creating viable cement bonded wood load bearing elements. The study involved creating multi layer nanocoating on the surface of poplar veneer using various polyelectrolyte combinations and numbers of treatment cycles, and testing the withdrawal resistance of the samples from a cement matrix. PDDA-PSS treatment was found to form increasingly uniform coating on the surface of wood, while the results were less straightforward for PAH-PSS. Both types and all levels of treatment caused dramatic improvement in load withdrawal resistance. The best result - a more than tenfold improvement - was achieved by at least 10 cycles of PDDA-PSS treatment. PAH-PSS treatment yielded a somewhat more modest improvement, which was already evident after five treatment cycles. The results point to the excellent potential of LbL nanocoating for creating cement bonded structural wood based composite materials.

  15. Influence of Bayer Red-mud on the Alkalinity of Cement-based Material Pore Solution and the Strength Development%拜耳法赤泥对水泥浆体孔溶液碱度及强度发展的影响

    Institute of Scientific and Technical Information of China (English)

    吴芳; 李利; 周代军; 李志杰

    2011-01-01

    通过测定同水胶比下拜耳法赤泥与普通硅酸盐水泥、硫铝酸盐水泥复配的水泥浆体孔溶液pH值和抗压强度,结合XRD分析研究了赤泥掺量对复配体系孔溶液碱度及抗压强度的影响.研究表明,普通硅酸盐水泥浆体和硫铝酸盐水泥浆体孔溶液碱度均随赤泥掺量的增加而增大.掺入赤泥并不会引起水泥水化后期孔溶液碱度的增加.普通硅酸盐水泥中赤泥掺量宜控制在30%以内,而硫铝酸盐水泥中赤泥掺量则不能超过20%.普通硅酸盐水泥孔溶液碱度发展与强度之间存在明显的相关性.%The pH value and compressive strengh of different bayer red-mud content with ordinary portland cement and sulphoaluminate cement paste pore solution under the same water cement ratio were tested ,The effect the red mud quantity were analyzed by XRD. Test results showed a linear increase in alkalinity of portland cement paste pore solution and sulphoaluminate cement paste pore solution with Bayer red-mud. Red mud would not increase the late alkalinity of cement-based material pore solution. the mixing amount of red mud in the portland cement should be in the range of thirty percent red mud, while the mixing amount of red mud in the sulphoaluminate cement should not exceed twenty percent. The correlation existed obvivualy between the alkalinity and strength of portland cement.

  16. Material Mismatch Effect on the Fracture of a Bone-Composite Cement Interface.

    Science.gov (United States)

    Khandaker, M; Tarantini, S

    2012-12-01

    The interfacial mechanics at the bone-implant interface is a critical issue for implant fixation and the filling of bone defects created by tumors and/or their excision. Our previous study found that micron and nano sizes MgO particles improved the fracture toughness of bone-cement interfaces under tension loading. The strength of bonding of different types of bone with different types of implants may not be the same. The aims of this research were to determine the influences of material mismatch due to bone orientation and a magnesium oxide (MgO) filler material for PMMA bone cement on the mechanical strength between bone and bone cement specimens. This research studied the longitudinal and transverse directions bovine cortical bone as different bone materials and poly Methyl MethAcrylate (PMMA) bone cement with and without MgO additives as different implant materials. The scope of work for this study was: (1) to determine the bending strength and modulus of different bone and bone cement specimens, (2) to determine whether inclusion of MgO particles on PMMA has any influence on these mechanical properties of PMMA, and (3) to determine whether bone orientation and inclusion of MgO particles with PMMA has any influence on the interface strength between bone and PMMA. This study showed that bone orientation has statistically significant effect on the bonding strength between bone and bone cement specimens (P value0.05).

  17. Optimization of an anion-exchange high performance liquid chromatography-inductively coupled plasma-mass spectrometric method for the speciation analysis of oxyanion-forming metals and metalloids in leachates from cement-based materials.

    Science.gov (United States)

    Mulugeta, Mesay; Wibetoe, Grethe; Engelsen, Christian J; Lund, Walter

    2010-10-01

    A method was developed for the speciation analysis of the oxyanions of As(III), As(V), Cr(VI), Mo(VI), Sb(III), Sb(V), Se(IV), Se(VI) and V(V) in leachates from cement-based materials, based on anion-exchange HPLC coupled with ICP-MS. The method was optimized in a two-step multivariate approach: the effect of sample pH and mobile phase composition on resolution, peak symmetry and analysis time was studied. Optimum conditions were then identified for the significant experimental factors by studying their interdependence. A mobile phase composition of 20 mM ammonium nitrate, 50 mM ammonium tartrate and pH 9.5 was found to be a compromise optimum for the separation of the target analytes using isocratic elution. The optimum condition provided separation of the analytes in less than 6 min, at a mobile phase flow rate of 1.0 mL/min. The signal intensities of the analytes were improved by adding 1% methanol to the mobile phase. The limit of detection of the method was in the range 0.2-2.2 μg/L for the various species. The effect of sample constituents was studied using spiked concrete leachates. The method was used to determine the target oxyanionic species in leachates generated from a concrete material in the pH range 3.5-12.4; CrO(4)(2-), MoO(4)(2-) and VO(4)(3-) were detected in most of the leachates.

  18. Mixing experimental research and application of rich cemented cemented sand and gravel dam materials%富浆胶凝砂砾料筑坝材料配合比试验研究及工程应用

    Institute of Scientific and Technical Information of China (English)

    闫国新; 施东松; 张雷顺

    2014-01-01

    通过对富浆胶凝砂砾料混凝土配合比设计进行试验研究,给出了推荐的配合比。该筑坝材料使工程节约了成本,最大限度的解决骨料紧张的问题,缩短了工期,为其他富浆胶凝砂砾料混凝土筑坝工程提供了设计参数。%Based on the rich cemented cemented sand and gravel concrete test,mix recommended was given.The dam materials makes the project cost savings,solves the aggregate tension,shortens the construction period,provides the design parameters for other rich ce-mented cemented sand and gravel concrete dam engineering.

  19. Improvement of Water Sensitivity of Macro-defect-free Cement Based Composites with Cross Coupling Agent

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The enhancement of interface bonding between cement and polymer and the structural reticulation of the water-soluble polymer are proposed to minimize the shortening of the mechanical properties of macro-defect-free (MDF) cement based composites at high relative humidity. The MDF composites incorporated with various cross-coupling agents were studied experimentally. The results show that the MDF composites modified with small amounts of cross-coupling agent had raised mechanical properties, but it is more important that the modified MDF composites had a significant increase in water resistance compared to the original one. In the meantime if the water resistant material such as fine powder of α-alumina was used to substitute for the unreacted cement grains in the MDF composites, a more efficient improvement of water resistance would be obtained. The loss in flexural strength of the MDF composites after 90 days of water immersion decreased from 62% before unmodified to 15% after modified.

  20. Effect of Selected Alternative Fuels and Raw Materials on the Cement Clinker Quality

    Science.gov (United States)

    Strigáč, Július

    2015-11-01

    The article deals with the study of the effects of alternative fuels and raw materials on the cement clinker quality. The clinker quality was expressed by the content of two principal minerals alite C3S and belite C2S. The additions of alternative fuels ashes and raw materials, in principle, always increased the belite content and conversely reduced the amount of alite. The alternative fuels with high ash content were used such as the meat-bone meal, sewage sludge from sewage treatment plants and paper sludge and the used alternative raw materials were metallurgical slags - granulated blastfurnace slag, air cooled blastfurnace slag and demetallized steel slag, fluidized bed combustion fly ash and waste glass. Meat-bone meal, sewage sludge from sewage treatment plants and paper sludge were evaluated as moderately suitable alternative fuels which can be added in the amounts of 2.8 wt. % addition of meat-bone meals ash, 3.64 wt. % addition of sewage sludge ash and 3.8 wt. % addition of paper sludge ash to the cement raw mixture. Demetallised steel slag is suitable for production of special sulphate resistant cement clinker for CEM I -SR cement with addition up to 5 wt. %. Granulated blastfurnace slag is a suitable alternative raw material with addition 4 wt. %. Air cooled blastfurnace slag is a suitable alternative raw material with addition 4.2 wt. %. Waste glass is not very appropriate alternative raw material with addition only 1.16 wt. %. Fluidized bed combustion fly ash appears not to be equally appropriate alternative raw material for cement clinker burning with less potential utilization in the cement industry and with addition 3.41 wt. %, which forms undesired anhydrite CaSO4 in the cement clinker.

  1. Effect of Selected Alternative Fuels and Raw Materials on the Cement Clinker Quality

    Directory of Open Access Journals (Sweden)

    Strigáč Július

    2015-11-01

    Full Text Available The article deals with the study of the effects of alternative fuels and raw materials on the cement clinker quality. The clinker quality was expressed by the content of two principal minerals alite C3S and belite C2S. The additions of alternative fuels ashes and raw materials, in principle, always increased the belite content and conversely reduced the amount of alite. The alternative fuels with high ash content were used such as the meat-bone meal, sewage sludge from sewage treatment plants and paper sludge and the used alternative raw materials were metallurgical slags - granulated blastfurnace slag, air cooled blastfurnace slag and demetallized steel slag, fluidized bed combustion fly ash and waste glass. Meat-bone meal, sewage sludge from sewage treatment plants and paper sludge were evaluated as moderately suitable alternative fuels which can be added in the amounts of 2.8 wt. % addition of meat-bone meals ash, 3.64 wt. % addition of sewage sludge ash and 3.8 wt. % addition of paper sludge ash to the cement raw mixture. Demetallised steel slag is suitable for production of special sulphate resistant cement clinker for CEM I –SR cement with addition up to 5 wt. %. Granulated blastfurnace slag is a suitable alternative raw material with addition 4 wt. %. Air cooled blastfurnace slag is a suitable alternative raw material with addition 4.2 wt. %. Waste glass is not very appropriate alternative raw material with addition only 1.16 wt. %. Fluidized bed combustion fly ash appears not to be equally appropriate alternative raw material for cement clinker burning with less potential utilization in the cement industry and with addition 3.41 wt. %, which forms undesired anhydrite CaSO4 in the cement clinker.

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

    Directory of Open Access Journals (Sweden)

    T. H. Panzera

    2010-03-01

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

  3. Experimental Calcium Silicate-Based Cement with and without Zirconium Oxide Modulates Fibroblasts Viability.

    Science.gov (United States)

    Slompo, Camila; Peres-Buzalaf, Camila; Gasque, Kellen Cristina da Silva; Damante, Carla Andreotti; Ordinola-Zapata, Ronald; Duarte, Marco Antonio Hungaro; de Oliveira, Rodrigo Cardoso

    2015-01-01

    The aim of this study was to verify whether the use of zirconium oxide as a radiopacifier of an experimental calcium silicate-based cement (WPCZO) leads to cytotoxicity. Fibroblasts were treated with different concentrations (10 mg/mL, 1 mg/mL, and 0.1 mg/mL) of the cements diluted in Dulbecco's modified Eagle's medium (DMEM) for periods of 12, 24, and 48 h. Groups tested were white Portland cement (WPC), white Portland cement with zirconium oxide (WPCZO), and white mineral trioxide aggregate Angelus (MTA). Control group cells were not treated. The cytotoxicity was evaluated through mitochondrial-activity (MTT) and cell-density (crystal violet) assays. All cements showed low cytotoxicity. In general, at the concentration of 10 mg/mL there was an increase in viability of those groups treated with WPC and WPCZO when compared to the control group (pzirconium oxide as the radiopacifier showed low cytotoxicity as a promising material to be exploited for root-end filling.

  4. Preparation and Performance Study of Cemented Filling Material Based on Fly Ash and Coal Gangue%粉煤灰-煤矸石基胶结充填材料制备与性能研究

    Institute of Scientific and Technical Information of China (English)

    孙庆巍; 朱涵; 崔正龙

    2012-01-01

    为了解决我国煤矿采空区地表沉陷以及“三下”压煤资源浪费的问题,提出以粉煤灰-水泥熟料-脱硫石膏复合胶凝材料为胶结材,原状粉煤灰为细骨料,破碎后的煤矸石为粗骨料制备新型煤矿开采胶结充填材料.依据正交试验结果和各因素影响规律趋势图,确定充填材料的优化配合比.研究结果表明,适当增大水泥熟料掺量可缩短材料初凝时间,减小水胶比能使材料强度显著提高,而材料坍落度可通过选取适宜的浆体中的固体质量分数和灰矸比来有效调节,当胶凝材料中水泥含量为15%,脱硫石膏含量为8%,水胶比为2,灰矸比为2∶3,浆体中的固体质量分数为70%时,充填材料性能可达到最佳.通过试验优选材料各项参数,工业废弃物可以用来制备高质量的胶结充填材料.%To solve problems of surface subsidence caused by mining of coal mine and waste of resources caused by unexploited coal under the surface construction, water body and railway, it was held by the authors that a new type of cemented filling material should be used, which was prepared from composite cementitious material composed of fly ash, cement and flue gas desulphurization gypsum as cementing material, raw fly ash as fine aggregates and coal gangue as coarse aggregates. In the light of the results of orthogonal experiment and tendency chart of influencing factor, optimized composition of the filling material was obtained. Results show that a increase in content of cement clinker can shorten setting time, decreasing water to binder ratio can enhance strength remarkably, that slump can be adjusted effectively through choosing suitable concentration and fly ash to coal gangue ratio, and that when content of cement clinker is 15% , content of flue gas desulphurization gypsum is 8% , water to binder ratio is 2, fly ash to coal gangue ratio is 2: 3 and the mass fraction of solids in paste is 70% , filling material has

  5. Cytotoxicity and genotoxicity of calcium silicate-based cements on an osteoblast lineage

    Directory of Open Access Journals (Sweden)

    Ana Lívia GOMES-CORNÉLIO

    2016-01-01

    Full Text Available Abstract Several calcium silicate-based biomaterials have been developed in recent years, in addition to Mineral Trioxide Aggregate (MTA. The aim of this study was to evaluate the cytotoxicity, genotoxicity and apoptosis/necrosis in human osteoblast cells (SAOS-2 of pure calcium silicate-based cements (CSC and modified formulations: modified calcium silicate-based cements (CSCM and three resin-based calcium silicate cements (CSCR1 (CSCR 2 (CSCR3. The following tests were performed after 24 hours of cement extract exposure: methyl-thiazolyl tetrazolium (MTT, apoptosis/necrosis assay and comet assay. The negative control (CT- was performed with untreated cells, and the positive control (CT+ used hydrogen peroxide. The data for MTT and apoptosis were submitted to analysis of variance and Bonferroni’s posttest (p < 0.05, and the data for the comet assay analysis, to the Kruskal-Wallis and Dunn tests (p < 0.05. The MTT test showed no significant difference among the materials in 2 mg/mL and 10 mg/mL concentrations. CSCR3 showed lower cell viability at 10 mg/mL. Only CSC showed lower cell viability at 50 mg/mL. CSCR1, CSCR2 and CSCR3 showed a higher percentage of initial apoptosis than the control in the apoptosis test, after 24 hours exposure. The same cements showed no genotoxicity in the concentration of 2 mg/mL, with the comet assay. CSC and CSCR2 were also not genotoxic at 10 mg/mL. All experimental materials showed viability with MTT. CSC and CSCR2 presented a better response to apoptosis and genotoxicity evaluation in the 10 mg/mL concentration, and demonstrated a considerable potential for use as reparative materials.

  6. CONTRIBUTION TO THE STATISTICAL INTERPRETATION OF RAW MATERIALS FOR THE CEMENT INDUSTRY OF SPLIT

    Directory of Open Access Journals (Sweden)

    Miroslav Matijaca

    1990-12-01

    Full Text Available Up to the last two decades cement was produced from mari called »tupina« (with about 76% CaCOj which is an ideal mixture for cement production. Due to the quantity decrease of this raw material, cement production went on using the mixture of other members of the flysch series: limestones, marls, clay, loess, sandstones a.o. By the analysis of natural materials the CaCO^ content has mostly been proved. Therefore, knowing the correlation of oxides in mineral raw material is of special significance. The article discusses investigation results of the correlation between CaCO-i and other oxides of the raw material (the paper is published in Croatian.

  7. Statistical Analyses of Optimum Partial Replacement of Cement by Fly Ash Based on Complete Consumption of Calcium Hydroxide

    Directory of Open Access Journals (Sweden)

    Ouypornprasert Winai

    2016-01-01

    Full Text Available The objectives of this technical paper were to propose the optimum partial replacement of cement by fly ash based on the complete consumption of calcium hydroxide from hydration reactions of cement and the long-term strength activity index based on equivalent calcium silicate hydrate as well as the propagation of uncertainty due to randomness inherent in main chemical compositions in cement and fly ash. Firstly the hydration- and pozzolanic reactions as well as stoichiometry were reviewed. Then the optimum partial replacement of cement by fly ash was formulated. After that the propagation of uncertainty due to main chemical compositions in cement and fly ash was discussed and the reliability analyses for applying the suitable replacement were reviewed. Finally an applicability of the concepts mentioned above based on statistical data of materials available was demonstrated. The results from analyses were consistent with the testing results by other researchers. The results of this study provided guidelines of suitable utilization of fly ash for partial replacement of cement. It was interesting to note that these concepts could be extended to optimize partial replacement of cement by other types of pozzolan which were described in the other papers of the authors.

  8. Effect of supplementary cementing materials on concrete resistance against carbonation and chloride ingress

    Energy Technology Data Exchange (ETDEWEB)

    Papadakis, V.G.

    2000-02-01

    In this work the durability of Portland cement systems incorporating supplementary cementing materials (SCM; silica fume, low- and high-calcium fly ash) is investigated. Experimental tests simulating the main deterioration mechanisms is reinforced concrete (carbonation and chloride penetration) were carried out. It was found that for all SCM tested, the carbonation depth decreases as aggregate replacement by SCM increases, and increases as cement replacement by SCM increases. The specimens incorporating an SCM, whether it substitutes aggregate or cement, when exposed to chlorides exhibit significantly lower total chloride content for all depths from the surface, apart from a thin layer near the external surface. New parameter values were estimated and existing mathematical models were modified to describe the carbonation propagation and the chloride penetration in concrete incorporating SCM.

  9. Tridimensional quantitative porosity characterization of three set calcium silicate-based repair cements for endodontic use.

    Science.gov (United States)

    De Souza, Erika Thuanne Gonçalves; Nunes Tameirão, Michele Dias; Roter, Juliana Marins; De Assis, Joaquim Teixeira; De Almeida Neves, Aline; De-Deus, Gustavo André

    2013-10-01

    The aim of the this study was to quantitatively evaluate in three-dimensional (3D), the porosity degree of three improved silicate-based endodontic repair cements (iRoot BP Plus®, Biodentine®, and Ceramicrete) compared to a gold-standard calcium silicate bioactive cement (Pro Root® MTA). From each tested cement, four samples were prepared by a single operator following the manufacturer's instructions in terms of proportion, time, and mixing method, using cylindrical plastic split-ring moulds. The moulds were lubricated and the mixed cements were inserted with the aid of a cement spatula. The samples were scanned using a compact micro-CT device (Skyscan 1174, Bruker micro-CT, Kontich, Belgium) and the projection images were reconstructed into cross-sectional slices (NRecon v.1.6.9, Bruker micro-CT). From the stack of images, 3D models were rendered and the porosity parameters of each tested material were obtained after threshold definition by comparison with standard porosity values of Biodentine®. No statistically significant differences in the porosity parameters among the different materials were seen. Regarding total porosity, iRoot BP Plus® showed a higher percentage of total porosity (9.58%), followed by Biodentine® (7.09%), Pro Root® MTA (6.63%), and Ceramicrete (5.91%). Regarding closed porosity, Biodentine® presented a slight increase in these numbers compared to the other sealers. No significant difference in porosity between iRoot BP Plus®, Biodentine®, and Ceramicrete were seen. In addition, no significant difference in porosity between the new calcium silicate-containing repair cements and the gold-standard MTA were found.

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

    OpenAIRE

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

    1992-01-01

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

  11. Characterization of environmentally-friendly alkali activated slag cements and ancient building materials

    Science.gov (United States)

    Sakulich, Aaron Richard

    Alternative cement technologies are an area of increasing interest due to growing environmental concerns and the relatively large carbon footprint of the cement industry. Many new cements have been developed, but one of the most promising is that made from granulated, ground blast furnace slag activated by a high-pH solution. Another is related to the discovery that some of the pyramid limestone blocks may have been cast using a combination of diatomaceous earth activated by lime which provides the high pH needed to dissolve the diatomaceous earth and bind the limestone aggregate together. The emphasis of this thesis is not on the latter---which was explored elsewhere---but on the results supplying further evidence that some of the pyramid blocks were indeed reconstituted limestone. The goal of this work is to chemically and mechanically characterize both alkali-activated slag cements as well as a number of historic materials, which may be ancient analogues to cement. Alkali activated slag cements were produced with a number of additives; concretes were made with the addition of a fine limestone aggregate. These materials were characterized mechanically and by XRD, FTIR, SEM, and TGA. Samples from several Egyptian pyramids, an 'ancient floor' in Colorado, and the 'Bosnian Pyramids' were investigated. In the cements, it has been unequivocally shown that C-S-H, the same binding phase that is produced in ordinary portland cement, has been produced, as well as a variety of mineral side products. Significant recarbonation occurs during the first 20 months, but only for the Na2CO3-activated formulae. Radiocarbon dating proves that the 'Bosnian Pyramids' and 'ancient floors' are not made from any type of recarbonated lime; however, Egyptian pyramid limestones were finite, thus suggesting that they are of a synthetic nature. XRD and FTIR results were inconclusive, while TGA results indicate the limestones are identical to naturally occurring limestones, and SEM

  12. Severe particulate pollution from the deposition practices of the primary materials of a cement plant.

    Science.gov (United States)

    Kourtidis, K; Rapsomanikis, S; Zerefos, C; Georgoulias, A K; Pavlidou, E

    2014-01-01

    Global cement production has increased twofold during the last decade. This increase has been accompanied by the installation of many new plants, especially in Southeast Asia. Although various aspects of pollution related to cement production have been reported, the impact of primary material deposition practices on ambient air quality has not yet been studied. In this study, we show that deposition practices can have a very serious impact on levels of ambient aerosols, far larger than other cement production-related impacts. Analyses of ambient particulates sampled near a cement plant show 1.3-30.4 mg/m(3) total suspended particulates in the air and concentrations of particles with a diameter of 10 μm or less at 0.04-3 mg/m(3). These concentrations are very high and seriously exceed air quality standards. We unequivocally attribute these levels to outdoor deposition of cement primary materials, especially clinker, using scanning electron microscopy/energy-dispersive X-ray spectroscopy. We also used satellite-derived aerosol optical depth maps over the area of study to estimate the extent of the spatial impact. The satellite data indicate a 33% decrease in aerosol optical depth during a 10-year period, possibly due to changing primary material deposition practices. Although the in situ sampling was performed in one location, primary materials used in cement production are common in all parts of the world and have not changed significantly over the last decades. Hence, the results reported here demonstrate the dominant impact of deposition practices on aerosol levels near cement plants.

  13. Improved microstructure of cement-based composites through the addition of rock wool particles

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Wei-Ting [Dept. of Civil Engineering, National Ilan University, Ilan 26047, Taiwan (China); Institute of Nuclear Energy Research, Atomic Energy Council, Taoyuan 32546, Taiwan (China); Cheng, An, E-mail: ancheng@niu.edu.tw [Dept. of Civil Engineering, National Ilan University, Ilan 26047, Taiwan (China); Huang, Ran; Zou, Si-Yu [Dept. of Harbor and River Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan (China)

    2013-10-15

    Rock wool is an inorganic fibrous substance produced by steam blasting and cooling molten glass. As with other industrial by-products, rock wool particles can be used as cementitious materials or ultra fine fillers in cement-based composites. This study investigated the microstructure of mortar specimens produced with cement-based composites that include various forms of rock wool particles. It conducted compressive strength testing, rapid chloride penetration tests, X-ray diffraction analysis, thermo-gravimetric analysis, and scanning electronic microscopy to evaluate the macro- and micro-properties of the cement-based composites. Test results indicate that inclusion of rock wool particles in composites improved compressive strength and reduced chloride ion penetration at the age of 91 days due to the reduction of calcium hydroxide content. Microscopic analysis confirms that the use of rock wool particles contributed to the formation of a denser, more compact microstructure within the hardened paste. In addition, X-ray diffraction analysis shows few changes in formation of pozzolanic reaction products and no new hydrations are formed with incorporating rock wool particles. - Highlights: • We report the microstructural characterization of cement-based composites. • Different mixes produced with various rock wool particles have been tested. • The influence of different mixes on macro and micro properties has been discussed. • The macro properties are included compressive strength and permeability. • XRD and SEM observations confirm the pozzolanic reaction in the resulting pastes.

  14. Electrical modelling of carbon nanotube cement-based sensors for structural dynamic monitoring

    Science.gov (United States)

    D'Alessandro, Antonella; Ubertini, Filippo; Materazzi, Annibale Luigi; Porfiri, Maurizio

    2014-06-01

    Some of the authors have recently developed a new nanocomposite cement-based sensor, termed "carbon nanotube cement-based sensor", for applications in vibration-based structural health monitoring of civil structures. The sensor is made of a self-sensing cement paste doped with multi walled carbon nanotubes. The mechanical deformation of this composite material results into a measurable change of its electrical resistance. Previous work was devoted to fabrication, dynamic characterization and to implementation in full-scale structural components. This work addresses electrical modelling of the sensor, and specifically seeks to validate a lumped circuit model for use in dynamic sensing. After a brief overview of carbon nanotube cement-based sensors, the electrical model is presented. Salient parameters of the circuit are identified on sensors with varying electrodes' morphologies. The results indicate that the proposed equivalent circuit model is capable of closely replicating the step response of the sensor to an imposed potential difference. Notably, such linear model is likely to anticipate superharmonic components in the electrical current in the response to sinusoidal mechanical deformations.

  15. Evaluation of Calcium Phosphate Cement As a Root Canal Sealer Filling Material

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Calcium phosphate cement for root end sealing was obtained by mixing α-tricalcium phosphate and additives with an aqueous solution of citric. Powder and liquid were mixed at a ratio of 1.25g/mL. The biocompatibility of this material was investigated primarily by subcutaneous implantation tests. Then calcium phosphate cement was used to fill three adult dogs' root canal, both calcium hydroxide paste and hydroxyapatite paste as control. The animals were killed at 4,12,20 weeks postoperatively respectively. The effects of different materials on the apical closure, restoration of periapical tissues and adaptability to the dentinal surface were examined by optical and electronic microscope. The observation at 20 weeks shows that the calcium phosphate cement has the potentialities of being a root canal sealer filling material available for pulpless teeth with open-apex and destructive periapical tissue.

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

    Science.gov (United States)

    Miller, M. Michael; Callaghan, Robert M.

    2004-01-01

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

  17. MACHINING OF NICKEL BASED ALLOYS USING DIFFERENT CEMENTED CARBIDE TOOLS

    Directory of Open Access Journals (Sweden)

    BASIM A. KHIDHIR

    2010-09-01

    Full Text Available This paper presents the results of experimental work in dry turning of nickel based alloys (Haynes – 276 using Deferent tool geometer of cemented carbide tools. The turning tests were conducted at three different cutting speeds (112, 152, 201and 269 m/min while feed rate and depth of cut were kept constant at 0.2 mm/rev and 1.5 mm, respectively. The tool holders used were SCLCR with insert CCMT-12 and CCLNR – M12-4 with insert CNGN-12. The influence of cutting speed, tool inserts type and workpiece material was investigated on the machined surface roughness. The worn parts of the cutting tools were also examined under scanning electron microscope (SEM. The results showed that cutting speed significantly affected the machined surface finish values in related with the tool insert geometry. Insert type CCMT-12 showed better surface finish for cutting speed to 201 m/min, while insert type CNGN-12 surface roughness increased dramatically with increasing of speed to a limit completely damage of insert geometer beyond 152 m/min.

  18. Pulp response to a novel adhesive calcium hydroxide based cement.

    Science.gov (United States)

    Watts, A; Paterson, R C; Cohen, B D; Combe, E C

    1994-09-01

    This study compares pulp responses to 3 formulations of calcium hydroxide, namely: a) An experimental adhesive calcium hydroxide cement containing polyacrylic acid, b) Dycal (L.D> Caulk Co, Milford, Delaware) Batch Nos 176970/176990, c) "Analar" calcium hydroxide mixed with sterile distilled water. After 28 days dentine bridges were present in 77% of teeth capped with the test material, 64% of teeth treated with Dycal and in 62% of teeth capped with calcium hydroxide and water. Inflammatory infiltrates were observed in a number of teeth remote from the bridges. Bacteria were detected in these specimens. Exposed rat molar pulp responses to an experimental adhesive calcium hydroxide cement were similar to to those observed with 2 other calcium hydroxide formulations.

  19. A new design of cemented stem using functionally graded materials (FGM).

    Science.gov (United States)

    Hedia, H S; Aldousari, S M; Abdellatif, A K; Fouda, N

    2014-01-01

    One of the most frequent complications of total hip replacement (THR) is aseptic loosening of femoral component which is primarily due to changes of post-operative stress distribution pattern with respect to intact femur. Stress shielding of the femur is known to be a principal factor in aseptic loosening of hip replacements. Many designers show that a stiff stem shields the surrounding bone from mechanical loading causing stress shielding. Others show that reducing stem stiffness promotes higher proximal interface shear stress which increases the risk of proximal interface failure. Therefore, the task of this investigation is to solve these conflicting problems appeared in the cemented total hip replacement. The finite element method and optimization technique are used in order to find the optimal stem material which gives the optimal available stress distribution between the proximal medial femoral bone and the cement mantle interfaces. The stem is designed using the concept of functionally graded material (FGM) instead of using the conventional most common used stem material. The results showed that there are four feasible solutions from the optimization runs. The best of these designs is to use a cemented stem graded from titanium at the upper stem layer to collagen at the lower stem layer. This new cemented stem design completely eliminates the stress shielding problem at the proximal medial femoral region. The stress shielding using the cemented functionally graded stem is reduced by 98% compared to titanium stem.

  20. Hardness of resin cement cured under different thickness of lithium disilicate-based ceramic

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xuan; WANG Fu

    2011-01-01

    Background The lithium disilicate-based ceramic is a newly developed all-ceramic material,which is lithium disilicate-based and could be used for fabricating almost all kinds of restorations.The extent of light attenuation by ceramic material was material-dependent.Ceramic materials with different crystal composition or crystalline content would exhibit distinct light-absorbing characteristics.The aim of this study was to analyze the influence of ceramic thickness and light-curing time on the polymerization of a dual-curing resin luting material with a lithium disilicate-based ceramic.Methods A lithium disilicate-based ceramic was used in this study.The light attenuation caused by ceramic with different thickness was determined using a spectral radiometer.The commercial dual-cured resin cement was light-cured directly or through ceramic discs with different thickness (1,2 and 3 mm,respectively) for different times (10,20,30,40,50 and 60 seconds,respectively).The polymerization efficiency of resin cement was expressed in terms as Vickers hardness (VHN) measured after 24 hours storage.Two-way analysis of variance (ANOVA) and Tukey's HSD tests were used to determine differences.Results Intensity of polymerizing light transmitted through ceramic discs was reduced from 584 mW/cm2 to about 216 mW/cm2,80 mW/cm2 and 52 mW/cm2 at thicknesses of 1 mm,2 mm and 3 mm,respectively.Resin cement specimens self-cured alone showed significantly lower hardness values.When resin cement was light-cured through ceramic discs with a thickness of 1 mm,2 mm and 3 mm,no further increasing in hardness values was observed when light-curing time was more than 30 seconds,40 seconds and 60 seconds,respectively.Conclusions Within the limitation of the present study,ceramic thickness and light-curing time had remarkable influence on the polymerization of dual-cured resin cement.When resin cement is light-cured beneath a lithium disilicate ceramic with different thickness,prolonging light

  1. Stochastic Modelling and Self Tuning Control of a Continuous Cement Raw Material Mixing System

    Directory of Open Access Journals (Sweden)

    Hannu T. Toivonen

    1980-01-01

    Full Text Available The control of a continuously operating system for cement raw material mixing is studied. The purpose of the mixing system is to maintain a constant composition of the cement raw meal for the kiln despite variations of the raw material compositions. Experimental knowledge of the process dynamics and the characteristics of the various disturbances is used for deriving a stochastic model of the system. The optimal control strategy is then obtained as a minimum variance strategy. The control problem is finally solved using a self-tuning minimum variance regulator, and results from a successful implementation of the regulator are given.

  2. A multi-scale micromechanical investigation on thermal conductivity of cement-based composites

    Science.gov (United States)

    Liu, Jiahan; Xu, Shilang; Zeng, Qiang

    2017-01-01

    Cement-based composites (CBCs) are one of the most widely used materials in construction. An appealing characterization of thermal conductivity of CBCs plays an essential role to evaluate the energy consumption in buildings and to facilitate the development of novel thermal insulation materials. Based on Eshelby equivalent inclusion principle and multi-scale methodology, this paper attempted to present a generalized multi-scale micromechanical model in terms of thermal performance of the CBCs, which covers some classic models for thermal conductivity estimation. A Mori-Tanaka homogenization method was applied to investigate the thermal conductivity of the CBCs of different compounds, water-to-cement ratios and curing ages. In addition, saturation degree factor was considered. The results of this model are in good agreement with the experimental value, showing that the multi-scale model developed in this paper is able to evaluate the thermal conductivity of the CBCs in different conditions.

  3. Effect of thermally induced strain on optical fiber sensors embedded in cement-based composites

    Science.gov (United States)

    Yuan, Li-bo; Zhou, Li-min; Jin, Wei; Lau, K. T.; Poon, Chi-kin

    2003-04-01

    A critical issue in developing a fiber-optic strain gauge is its codependency on temperature and strain. Any changes in the output of the optical fiber sensor due to its own thermal sensitivity and the thermal expansion of the most material will be misinterpreted as a change in shape-induced strain in the structure. This codependence is often referred to as thermally induced apparent strain or simply apparent strain. In this paper, an analytical model was developed to evaluate the thermally induced strain in fiber optic sensors embedded in cement-based composites. The effects of thermal induced strain on embedded optical fiber were measured with a white-light fiber-optic Michelson sensing interferometer for a number of cement-based host materials.

  4. Development of near-zero water consumption cement materials via the geopolymerization of tektites and its implication for lunar construction

    Science.gov (United States)

    Wang, Kai-Tuo; Tang, Qing; Cui, Xue-Min; He, Yan; Liu, Le-Ping

    2016-07-01

    The environment on the lunar surface poses some difficult challenges to building long-term lunar bases; therefore, scientists and engineers have proposed the creation of habitats using lunar building materials. These materials must meet the following conditions: be resistant to severe lunar temperature cycles, be stable in a vacuum environment, have minimal water requirements, and be sourced from local Moon materials. Therefore, the preparation of lunar building materials that use lunar resources is preferred. Here, we present a potential lunar cement material that was fabricated using tektite powder and a sodium hydroxide activator and is based on geopolymer technology. Geopolymer materials have the following properties: approximately zero water consumption, resistance to high- and low-temperature cycling, vacuum stability and good mechanical properties. Although the tektite powder is not equivalent to lunar soil, we speculate that the alkali activated activity of lunar soil will be higher than that of tektite because of its low Si/Al composition ratio. This assumption is based on the tektite geopolymerization research and associated references. In summary, this study provides a feasible approach for developing lunar cement materials using a possible water recycling system based on geopolymer technology.

  5. 聚甲基酰亚胺泡沫改性水泥基复合吸声材料的制备与吸声性能研究%Study on the preparation of cement base sound absorption composite materials modifidied with polymethacrylimide foam (PMI) and the sound-absorbing performance of the composite material

    Institute of Scientific and Technical Information of China (English)

    彭龙贵; 杨晓凤; 李颖; 杜春宝; 王启强

    2011-01-01

    以普通硅酸盐水泥为基体,聚甲基丙烯酰亚胺(PMI)泡沫为填料制作水泥基吸声复合材料.实验采用半干法工艺成型,主要考察了水灰比、铝粉掺入量和聚甲基丙烯酰亚胺(PMI)掺入量等因素对复合材料材料吸声性能的影响,尤其是对频率f<300 Hz范围内声音的吸声性能的影响.实验中采用驻波管和SEM扫描仪对样品的吸声系数和微观结构进行了测量和分析.结果表明:当水灰比为0.55、铝粉的掺入量为0.04%、聚甲基丙烯酰亚胺(PMI)的掺入量为2.5%时,对频率f<300 Hz范围内的声音的吸声系数的平均值为0.348.%:In this paper,cement-based sound-absorbing composite material is made with ordinary portland cement as matrix and polymethacrylimide foam (PMI) as the filler. Semi-dry forming process is used in experiments, mainly for regulating water-cement ratio.amount of aluminum powder mixing ,polymethacrylimide(PMI) mixing effect on the sound absorption properties .especially of the low frequency sound of /<300 Hz . Standing wave tube and SEM is used in experiments to measure the absorption coefficient of the sample and observe the microstructure of the sample. The results show that when the water cement ration is 0. 55.amount of aluminum powder mixing is 0. 04%.and the amount of polymethacrylimide (PMI) mixing is 2. 5%. The average value of the absorption coefficient on the frequency sound of /<300 Hz is 0. 348.

  6. Cemented materials in the LLW and MLW Spanish disposal

    Directory of Open Access Journals (Sweden)

    Guerrero, A.

    1999-09-01

    Full Text Available BWR and PWR cemented matrices to confine low and medium simulated liquid radioactive wastes have been submitted to the leaching process in de-ionized water at 20ºC and 40ºC, to obtain the medium leachability index (L and the effective diffusion coefficient (De of different ions. Otherwise, it has been studied the associated expansion of the backfilling mortar of the concrete containers of the Spanish repository of these wastes, due to a possible attack of the sulfate ions coming from the cemented matrices.

    Matrices cementicias confinantes tipo BWR y PWR de residuos simulados de baja y media radiactividad se han sometido a procesos de lixiviación en agua desionizada a 20ºC y 40ºC, obteniéndose los índices medios de lixiviación (L y el coeficiente de difusión efectiva (De de algunos iones. Por otra parte, se ha estudiado la expansión asociada a un mortero de relleno constitutivo del depósito de almacenamiento de los residuos, por posible ataque de los iones SO4-2 procedentes de las matrices.

  7. Heuristic economic assessment of the Afghanistan construction materials sector: cement and dimension stone production

    Science.gov (United States)

    Mossotti, Victor G.

    2014-01-01

    Over the past decade, the U.S. Government has invested more than $106 billion for physical, societal, and governmental reconstruction assistance to Afghanistan (Special Inspector General for Afghanistan Reconstruction, 2012a). This funding, along with private investment, has stimulated a growing demand for particular industrial minerals and construction materials. In support of this effort, the U.S. Geological Survey released a preliminary mineral assessment in 2007 on selected Afghan nonfuel minerals (Peters and others, 2007). More recently, the 2007 mineral assessment was updated with the inclusion of a more extensive array of Afghan nonfuel minerals (Peters and others, 2011). As a follow-up on the 2011 assessment, this report provides an analysis of the current use and prospects of the following Afghan industrial minerals required to manufacture construction materials: clays of various types, bauxite, gypsum, cement-grade limestone, aggregate (sand and gravel), and dimension stone (sandstone, quartzite, granite, slate, limestone, travertine, marble). The intention of this paper is to assess the: Use of Afghan industrial minerals to manufacture construction materials, Prospects for growth in domestic construction materials production sectors, Factors controlling the competitiveness of domestic production relative to foreign imports of construction materials, and Feasibility of using natural gas as the prime source of thermal energy and for generating electrical energy for cement production. The discussion here is based on classical principles of supply and demand. Imbedded in these principles is an understanding that the attributes of supply and demand are highly variable. For construction materials, demand for a given product may depend on seasons of the year, location of construction sites, product delivery time, political factors, governmental regulations, cultural issues, price, and how essential a given product might be to the buyer. Moreover, failure on the

  8. Characterization of dicalcium phosphate dihydrate cements prepared using a novel hydroxyapatite-based formulation

    Energy Technology Data Exchange (ETDEWEB)

    Alge, Daniel L [Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47908 (United States); Cruz, Grace Santa; Chu, Tien-Min Gabriel [Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202 (United States); Goebel, W Scott, E-mail: tgchu@iupui.ed [Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202 (United States)

    2009-04-15

    Dicalcium phosphate dihydrate (DCPD) cements are typically prepared using beta-tricalcium phosphate (beta-TCP) as the base component. However, hydroxyapatite (HA) is an interesting alternative because of its potential for reducing cement acidity, as well as modulating cement properties via ionic substitutions. In the present study, we have characterized DCPD cements prepared with a novel formulation based on monocalcium phosphate monohydrate (MCPM) and HA. Cements were prepared using a 4:1 MCPM:HA molar ratio. The reactivity of HA in this system was verified by showing DCPD formation using poorly crystalline HA, as well as highly crystalline HA. Evaluation of cements prepared with poorly crystalline HA revealed that setting occurs rapidly in the MCPM/HA system, and that the use of a setting regulator is necessary to maintain workability of the cement paste. Compressive testing showed that MCPM/HA cements have strengths comparable to what has previously been published for DCPD cements. However, preliminary in vitro analysis of cement degradation revealed that conversion of DCPD to HA may occur much more rapidly in the MCPM/HA system compared to cements prepared with beta-TCP. Future studies should investigate this property further, as it could have important implications for the use of HA-based DCPD cement formulations.

  9. Autogenous Phenomena in Cement-Based Materials

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    Denne afhandling er skrevet med henblik på opnåelse af den danske doktorgrad i teknik, dr.techn. Den vedrører autogene fænomener i cementbaserede materialer – primært deformation og ændring af den relative luftfugtighed (RF). I afhandlingen er det belyst, hvordan betydningen af disse fænomener bl...

  10. Experimental studies on the inventory of cement-derived colloids in the pore water of a cementitious backfill material

    Energy Technology Data Exchange (ETDEWEB)

    Wieland, E

    2001-06-01

    experimental results of the study. Predictions of the colloidal effect on radionuclide mobility were based on the assumption that colloids dispersed in the pore water of the backfill material may reduce radionuclide sorption (R{sub d} values) on cement. This effect was described in terms of a sorption reduction factor. The distribution ratios (R{sub c}) of radionuclides between the cement pore water and the colloidal phase as well as the colloid mass concentration (m{sub c}) are the two important colloidal parameters affecting sorption reduction. No significant sorption reduction is expected for weakly and moderately sorbing radionuclides (R{sub d} {<=} 1 m{sup 3} kg{sup -1}) up to a colloid concentration of 1 ppm. Moreover, no significant sorption reduction is anticipated for strongly sorbing radionuclides (R{sub d} > 1 m{sup 3} kg{sup -1}) below colloid concentrations of 0.1 ppm. This value is considered to be representative for the backfill material. At higher colloid concentrations, however, sorption reduction may occur in case of the strongly sorbing radionuclides. Nevertheless, due to an extremely strong uptake of these elements by cement in the absence of colloids, the effective sorption values in the presence of colloids are predicted to be still high. (author)

  11. Bond strength of a resin cement to a cured composite inlay material.

    Science.gov (United States)

    Latta, M A; Barkmeier, W W

    1994-08-01

    Although resin cements have been effectively bonded to mineralized tooth structures, bonding to a cured composite material has remained a challenge. This study evaluated the shear bond strength of a resin cement bonded to a cured composite inlay material by use of a variety of composite surface treatments: (1) hydrofluoric acid/60 seconds, (2) ammonium bifluoride/60 seconds, (3) resin adhesive, (4) microabrasion with 50 microns aluminum oxide, and (5) microabrasion with 50 microns aluminum oxide and application of a resin adhesive. The resin cement was also bonded to human enamel that was etched with phosphoric acid. Scanning electron microscopy examinations were completed to evaluate the effects of the composite surface treatments. The results indicated that microabrasion of a cured composite enhances bonding of a resin cement. The bond strength of a resin cement to a composite surface that was air abraded with aluminum oxide, with or without the application of a resin adhesive, was higher than surface treatments with hydrofluoric acid or ammonium bifluoride. Scanning electron microscopy indicated that an irregular surface on the composite was created with aluminum oxide air abrasion.

  12. Investigation of cement based composites made with recycled rubber aggregate

    Directory of Open Access Journals (Sweden)

    Jevtić Dragica Lj.

    2012-01-01

    Full Text Available The results of experimental investigations performed on cement based composites made with addition of recycled rubber as a partial replacement of natural river aggregate are presented in this paper. Different properties of cement based mortar were analyzed, both in fresh and in hardened state. Tested properties in the fresh state included: density, consistency and volume of entrained air. In the hardened state, the following properties were tested: density, mechanical properties (compressive and flexural strength, modulus of elasticity, adhesion to concrete substrate, water absorption, freeze-thaw resistance and ultrasonic pulse velocity. The obtained results indicate that recycled rubber can be successfully applied as a partial replacement of natural river aggregate in cement based composites, in accordance with the sustainable development concept. The investigation showed that physical-mechanical properties of cementituous composites depend to a great extent on the percentage of replacement of natural river aggregate with recycled rubber, especially when the density, strength, adhesion and freeze-thaw resistance are concerned. The best results were obtained in the freeze-thaw resistance of such composites.

  13. Solid phase characterization and gas transfers through unsaturated porous media: experimental study and modeling applied diffusion of hydrogen through cement-based materials; Caracterisation de la phase solide et transferts de gaz dans les milieux poreux insatures: etude experimentale et modelisation appliquees a la diffusion de l'hydrogene dans les materiaux cimentaires

    Energy Technology Data Exchange (ETDEWEB)

    Vu, T.H.

    2009-10-15

    This thesis documents the relationship between the porous microstructure of cement based materials and theirs gaseous diffusivity properties relative to the aqueous phase location and the global saturation level of the material. The materials studied are cement pastes and mortars. To meet the thesis objective, the materials are characterized in detail by means of several experimental methods: mercury intrusion porosimetry, water porosimetry, thermo-poro-metry, nitrogen sorption and water desorption. In addition, diffusion tests realized on materials maintained in controlled humidity chambers allow obtaining the effective hydrogen diffusivity as function of the microstructure and the saturation state of material with a gas chromatography. The experimental results are then used as a data base that is compared to a modeling approach. The model developed consists of a combination of ordinary diffusion (Fick regime) and Knudsen diffusion of hydrogen. The model also accounts for the effects of the liquid curtains, the impact of tortuosity on gas diffusion, and the saturation level of the porous system. (author)

  14. GIS Based Multi-Criteria Decision Analysis For Cement Plant Site Selection For Cuddalore District

    Science.gov (United States)

    Chhabra, A.

    2015-12-01

    India's cement industry is a vital part of its economy, providing employment to more than a million people. On the back of growing demands, due to increased construction and infrastructural activities cement market in India is expected to grow at a compound annual growth rate (CAGR) of 8.96 percent during the period 2014-2019. In this study, GIS-based spatial Multi Criteria Decision Analysis (MCDA) is used to determine the optimum and alternative sites to setup a cement plant. This technique contains a set of evaluation criteria which are quantifiable indicators of the extent to which decision objectives are realized. In intersection with available GIS (Geographical Information System) and local ancillary data, the outputs of image analysis serves as input for the multi-criteria decision making system. Moreover, the following steps were performed so as to represent the criteria in GIS layers, which underwent the GIS analysis in order to get several potential sites. Satellite imagery from LANDSAT 8 and ASTER DEM were used for the analysis. Cuddalore District in Tamil Nadu was selected as the study site as limestone mining is already being carried out in that region which meets the criteria of raw material for cement production. Several other criteria considered were land use land cover (LULC) classification (built-up area, river, forest cover, wet land, barren land, harvest land and agriculture land), slope, proximity to road, railway and drainage networks.

  15. Compound soil-tyre chips modified by cement as a road construction material

    Directory of Open Access Journals (Sweden)

    Panu Promputthangkoon

    2013-10-01

    Full Text Available This research attempts to overcome the two problems of low-quality soil and a growing number of discarded tyres bymixing low-CBR soil with recycled tyre chips. The compound soil-tyre chips was then stabilised by Portland cement with theaim of using them as a new material in road construction in order to reduce the occurrence of shrinkage cracks. To achievethe purposes of this research three standard geotechnical testing programmes were employed: (1 modified compaction tests,(2 California Bearing Ratio tests (CBR, and (3 unconfined compression tests. The modified compaction test results provedthat for the mixtures having very low tyre chips and cement content, the behaviour is very complex. It was also observed thatthe greater the percentage of rubber added the lower the global density. However, this is predictable as the specific gravityof the rubber is much lower than that of the soil. For the relationship between the optimum moisture content (OMC and thecement content, it was observed that there is no clear pattern.For the specimens having no cement added, the CBR for unsoaked specimens was observed to be greater than that forsoaked specimens. However, when the cement was introduced the CBR test showed that the resistance to penetration for thesoaked specimens was significantly greater, indicating the effects of cement added on the strength. In addition, it was foundthat the CBR values for both soaked and unsoaked specimens gradually increased with the increase of cement content.Lastly, the unconfined compressive strength progressively increased with the increased percentage of cement.

  16. Effect of artificial saliva and pH on shear bond strength of resin cements to zirconia-based ceramic.

    Science.gov (United States)

    Geramipanah, F; Majidpour, M; Sadighpour, L; Fard, M J Kharazi

    2013-03-01

    The aim of the present study was to evaluate the effect of media with different pH on shear and strength of resin cements to zirconia-based ceramics. Sixty rectangularly shaped specimens made of a zirconia based ceramic (Cercon, Dentsply) were prepared, air-blasted with 110 microm aluminum oxide particles (Al203) and randomly assigned into three groups (n = 30). A universal resin composite (Filtek Z250, 3M/ESPE) was bonded to each specimen using one of the following three cements: Calibra (Dentsply), Panavia F2 (kurary) and Unicem (3M/ESPE). Specimens were thermal cycled and stored in one of the following three media for two weeks: water at pH = 7, saliva at pH = 7 and saliva at pH = 3.5. The mean shear bond strength of each group was analyzed using the Kruskal-Wallis test (alpha = 0.05). The modes of failure were recorded using a streomicroscope. All specimens in the Calibra groups showed premature debonding. No significant difference was found between the two other cements or different media. The failure modes in the two latter cements were predominantly adhesive. Despite the adverse effect of acidic media on the properties of restorative materials, the media did not significantly influence the bond strength of MDP-containing resin cement and a self-adhesive cement to a zirconia- based ceramic.

  17. RE-USE OF SPENT CATALYST FROM OIL-CRACKING REFINERIES AS SUPPLEMENTARY CEMENTING MATERIAL

    Institute of Scientific and Technical Information of China (English)

    S. K. Antiohos; E. Chouliara; S. Tsimas

    2006-01-01

    Advanced technological achievements and the continuous growth of economy have made the disposal,recycle and reuse of industrial by-products a severe challenge. The cement industry is considered one of the key sectors in this effort in successfully (in terms of not extenuating but improving some of the properties of the final product) absorbing large quantities of solid wastes, either as aggregates or as secondary cementitious materials. This not only contributes to the creation of an energy and CO2-emission depository (as commonly used raw materials are spared), but also simultaneously alleviates the acute environmental burden caused by the irresponsible disposal of such by-products. In this study, the possibility of reusing spent fluid catalytic-cracking catalyst (FCC) as a supplementary cementing material(SCM) was examined. A series of tests were conducted, initially aiming at characterizing the material and thereafter evaluating its pozzolanic activity and its effect on the mechanical properties of blended cements. Major findings in this investigation revealed that the use of FCC as a mineral admixture in cement is feasible, strengthening the belief that siliceous glassy residues should represent a steady supply for the construction sector.

  18. 基于多元非线性回归优化制备碱钢渣胶凝材料%Optimized Preparation of Alkaline Steel Slag Cement Materials Based on Multivariate Nonlinear Regression

    Institute of Scientific and Technical Information of China (English)

    张庆丰; 张浩; 陆彪

    2016-01-01

    以钢渣作为研究对象,采用水玻璃、氢氧化钠与氢氧化钙三元复合活化剂,制备碱钢渣胶凝材料。基于均匀设计和多元非线性回归法研究了各因素对碱钢渣胶凝材料力学性能的影响。结果表明,各因素对性能影响的主次顺序为:3 d时钢渣用量>氢氧化钠用量>水玻璃用量>氢氧化钙用量,7 d时钢渣用量>水玻璃用量>氢氧化钠用量>氢氧化钙用量,28 d时钢渣用量>水玻璃用量>氢氧化钙用量>氢氧化钠用量;28 d碱钢渣胶凝材料的优化制备方案为:钢渣用量为225 g,水玻璃用量为22.5 g,氢氧化钠用量为9.0 g,氢氧化钙用量为13.2 g;优化制备模型选择正确,其相对误差仅为2.19%。%Alkaline steel slag cement materials were prepared with steel slag as the research object, sodium silicate, sodium hydroxide and calcium hydroxide as the ternary compound activator. The effect of every factor on mechanical property of alkaline steel slag cement materials was studied by orthogonal design and multivariate nonlinear regression. The results show that primary and secondary sequence of factors is steel slag dosage>sodium hydroxide dosage>sodium silicate dosage>calcium hydroxide dosage in 3 d, steel slag dosage>sodium silicate dosage>sodium hydroxide dosage>calcium hydroxide dosage in 7 d, steel slag dosage>sodium silicate dosage>calcium hydroxide dosage>sodium hydroxide dosage in 28 d. The optimization program of alkaline steel slag cement materials in 28 d is steel slag dosage 225 g, sodium silicate dosage 22.5 g, sodium hydroxide dosage 9.0 g and calcium hydroxide dosage 13.2 g. Optimized preparation model is correct, its relative error is only 2.19%.

  19. USE OF CONSTRUCTION AND DEMOLITION WASTES AS RAW MATERIALS IN CEMENT CLINKER PRODUCTION

    Institute of Scientific and Technical Information of China (English)

    Christos-Triantafyllos Galbenis; Stamatis Tsimas

    2006-01-01

    The aim of the present paper was to investigate the possibility of utilizing Construction and Demolition(C&D) wastes as substitutes of Portland cement raw meal. The C&D wastes that were so used, were the Recycled Concrete Aggregates (RCA) and the Recycled Masonry Aggregates (RMA) derived from demolished buildings in Attica region, Greece. RCA and RMA samples were selected because of their calcareous and siliceous origin respectively,which conformed the composition of the ordinary Portland cement raw meal. For that reason, six samples of cement raw meals were prepared: one with ordinary raw materials, as a reference sample, and five by mixing the reference sample with RCA and RMA in appropriate proportions. The effect on the reactivity of the generated mixtures, was evaluated on the basis of the free lime content (fCaO) in the mixtures sintered at 1350℃, 1400℃ and 1450℃. Test showed that the added recycled aggregates improved the burnability of the cement raw meal without affecting negatively the cement clinker properties. Moreover, the formation of the major components (C3S, C2S, C3A and C4AF) of the produced clinkers(sintered at 1450℃) was corroborated by X-Ray Diffraction (XRD).

  20. Hydration Products of Fly Ash Based Cementing Material Activated By NaOH%NaOH激发粉煤灰基胶凝材料的水化产物

    Institute of Scientific and Technical Information of China (English)

    李辉; 诸葛丽君; 史诗; 徐德龙

    2012-01-01

    A fly-ash based alkali-activated cementing material (FACM) was prepared by using fly ash as a raw material and NaOH as an activating agent. The effect of curing conditions on the compression strength of FACM was investigated. The mineral composition of FACM at different ages was analyzed by X-ray diffracion. The microstructure and element composition of hydration products of this material at different ages were characterized by scanning electron microscope with X-ray energy dispersive technique. The results show that the compression strength of FACM is enhanced under steam curing condition. The glass phase in fly ash participated in the hydration reaction, but the inert phases such as mullite, quartz, magnetite, etc. did not be involved in. Zeolite precursor formed in the pore of FACM in the early hydration process, and the particle size grew up to 1 pin with the cross-shape after cured for I d. With the prolonging of curing time, the particle size could be 5 ~tm. With the time prolonged, the particles overlapped with each other, filled in the entire pore and formed the compact reticulate structure, favoring the improvement of the compression strength of materials.%以粉煤灰为原料,NaOH为激发剂,制备出高抗压强度的粉煤灰基碱激发胶凝材料,研究养护条件对粉煤灰基碱激发胶凝材料抗压强度的影响。用x射线衍射分析不同龄期粉煤灰基碱激发胶凝材料的矿物组成,并用带能谱分析的扫描电镜观察不同龄期材料的微观形貌和区域元素组成。结果表明:蒸汽养护可以显著提高材料的抗压强度:粉煤灰中的玻璃相参加材料的水化反应,莫来石、石英等晶相则为惰性物质,不参加反应:在水化过程早期,粉煤灰基碱激发胶凝材料的气孔内会形成钠系菱沸石的前驱体,蒸汽养护1d后长大为表面呈十字交叉状的1pm左右颗粒,随着时间延长,这些颗粒可长至5μm左右,交错重叠充满

  1. Evaluation of leaching behavior and immobilization of zinc in cement-based solidified products

    Directory of Open Access Journals (Sweden)

    Krolo Petar

    2012-01-01

    Full Text Available This study has examined leaching behavior of monolithic stabilized/solidified products contaminated with zinc by performing modified dynamic leaching test. The effectiveness of cement-based stabilization/solidification treatment was evaluated by determining the cumulative release of Zn and diffusion coefficients, De. The experimental results indicated that the cumulative release of Zn decreases as the addition of binder increases. The values of the Zn diffusion coefficients for all samples ranged from 1.210-8 to 1.1610-12 cm2 s-1. The samples with higher amounts of binder had lower De values. The test results showed that cement-based stabilization/solidification treatment was effective in immobilization of electroplating sludge and waste zeolite. A model developed by de Groot and van der Sloot was used to clarify the controlling mechanisms. The controlling leaching mechanism was found to be diffusion for samples with small amounts of waste material, and dissolution for higher waste contents.

  2. Feasibility of Pulverized Oyster Shell as a Cementing Material

    Directory of Open Access Journals (Sweden)

    Chou-Fu Liang

    2013-01-01

    Full Text Available This research intends to study the cementing potential of pulverized oyster shell, rich in calcium, when mixed with fly ash and soil. Cylindrical compacted soil and cubic lime specimens with different proportions of the shells and fly ash are made to study the strength variance. Soil, which is classified as CL in the USCS system, commercialized pulverized oyster shell, F-type fly ash, and lime are mixed in different weight percentages. Five sample groups are made to study the compressive strength of soil and lime specimens, respectively. The lime cubes are made with 0.45 W/B ratio and the cylindrical soils are compacted under the standard Procter compaction process with 20% moisture content. The results show that increment of shell quantity result to lower strength on both the soil and lime specimens. In a 56-day curing, the compressive strength of the lime cubes containing fly ash increases evidently while those carrying the shell get little progress in strength. The soil specimens containing fly ash gradually gain strength as curing proceeds. It suggests that mixtures of the shell and fly ash do not process any Pozzolanic reaction nor help to raise the unconfined strength of the compacted soil through the curing.

  3. [Burns caused by cement mortar (based on expert opinion)].

    Science.gov (United States)

    Kleinhans, D

    1984-01-01

    A 35-year-old farmer with scars on his right arm, following erosion obviously due to wet cement (case of an expert opinion), was examined. Cement water had continuously soaked his shirt while he was planing a freshly applied wet cement ceiling with his right arm upwards. The cement did not contain special additives, so the normal alkalinity of wet cement and occlusion effects caused the erosion. The farmer sued the manufacturer of the cement for damages because of missing warning notices. The court decided in his favor.

  4. New Development and Research Area of Cementing Material and Technology%固井材料技术新进展及研究方向

    Institute of Scientific and Technical Information of China (English)

    齐奉忠; 杜建平; 魏群宝

    2015-01-01

    As the exploration and development work is extending into the fields of deep layers, low-pressure, low permeability and low abundance as well as offshore areas and non-conventional reservoirs, oil and gas well cementing becomes more and more difficult and calls for higher requirements on long-term cementing quality. Research and development of cementing materials face new challenges. This paper summarizes the technological achievements of cement slurry systems and materials made in recent years in the areas of ultra-high density cement slurry, ultra-low density cement slurry, large temperature difference cement slurry, salt-resistant latex cement slurry, lfexible cement, CO2 corrosion-resistant cement, phosphate cement, and low hydrate heat and low temperature cement. It also briefs about technological development of high temperature-resistant spacer lfuid, high-efifciency lfushing spacer lfuid and oil displacement high-density spacer lfuid. Based on the company’s cementing service business, the paper idienifes the future research areas –study of cementing material mechanism, improvement of cement slurry formula and additive performance, and development of new-type cementing materials.%随着勘探开发工作的逐步深入以及向“深(深层)、低(低压、低渗透、低丰度)、海(海洋)、非(非常规储层)”领域的拓展,油气井固井难度显著增加,对长期封固质量的要求越来越高,固井材料研发及应用面临新的挑战。文章从超高密度水泥浆、超低密度水泥浆、大温差水泥浆、抗盐胶乳水泥浆、韧性水泥、防C O2腐蚀水泥、磷酸盐水泥、低水化热低温水泥等方面总结了近来水泥浆体系和材料的技术进展,以及抗高温隔离液、高效冲洗隔离液、驱油型高密度隔离液等方面取得的技术进步。根据公司固井作业面临的形势,从固井材料机理研究、水泥浆配方及外加剂性能完善、新型固井

  5. Micromechanics of the Interface in Fibre-Reinforced Cement Materials

    DEFF Research Database (Denmark)

    Stang, Henrik; Shah, S.P.

    1996-01-01

    the strength and ductility of the brittlematrix material rather than changing the overall stiffness,the ability of the fibres to interact with cracking processes in thematrix material is essential. Furthermore, since matrix cracking in afibre reinforced material can only take place with simultaneousinterfacial...

  6. Cytotoxicity of calcium enriched mixture cement compared with mineral trioxide aggregate and intermediate restorative material.

    Science.gov (United States)

    Mozayeni, Mohammad A; Milani, Amin S; Marvasti, Laleh A; Asgary, Saeed

    2012-08-01

    Calcium enriched mixture (CEM) cement has been recently invented by the last author. It is composed of calcium oxide, calcium phosphate, calcium silicate and calcium sulphate; however, it has a different chemical composition to mineral trioxide aggregate (MTA). The purpose of this ex vivo study was to investigate the cytotoxicity of CEM cement, and compare it with intermediate restorative material (IRM) and MTA. The materials were tested in fresh and set states on L929 fibroblasts to assess their cytotoxicity. The cell viability responses were evaluated with methyl-tetrazolium bromide assay and Elisa reader at 1, 24 and 168 h (7 days). The tested materials were eluted with L929 culture medium according to international standard organisation 109935 standard. Distilled water and culture medium served as positive and negative controls, respectively. Differences in cytotoxicity were evaluated by one-way anova and t-tests. The cytotoxicity of the materials was statistically different at the three time intervals (P IRM subgroups were the most cytotoxic root-end/dental material (P IRM because of lower cytotoxicity. CEM cement also has good biocompatibility as well as lower estimated cost to MTA and seems to be a promising dental material.

  7. Frost Resistance and Permeability of Cement Stabilized Gravel used as Filling Material for Pearl-Chain Bridges

    DEFF Research Database (Denmark)

    Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard; Hertz, Kristian Dahl

    2014-01-01

    The Pearl-Chain Bridge Technology introduces a new innovative arch bridge solution which com-bines the statical advantages of an arch bridge with a minimum of traffic disturbance. The arch-shaped substructure is stabilized by a filling material, e.g. cement stabilized gravel, which should meet...... higher for a cement content of 4% compared to 5%....

  8. EFFECT OF FLUORIDE-CONTAINING DESENSITIZING AGENTS ON THE BOND STRENGTH OF RESIN-BASED CEMENTS TO DENTIN

    Science.gov (United States)

    Saraç, Duygu; Külünk, Safak; Saraç, Y. Sinasi; Karakas, Özlem

    2009-01-01

    Objective: The objective of this study was to evaluate the effect of desensitizing agents containing different amounts of fluoride on the shear bond strength of a dual polymerized resin cement and a resin-modified glass ionomer cement (RMGIC) to dentin. Material and Methods: One hundred human molars were mounted in acrylic resin blocks and prepared until the dentin surface was exposed. The specimens were treated with one of four desensitizing agents: Bifluorid 12, Fluoridin, Thermoline and PrepEze. The remaining 20 specimens served as untreated controls. All groups were further divided into 2 subgroups in which a dual polymerized resin cement (Bifix QM) or a resin-modified glass ionomer cement (AVANTO) was used. The shear bond strength (MPa) was measured using a universal testing machine at a 0.5 mm/min crosshead speed. The data were analyzed statistically with a 2-way ANOVA, Tukey HSD test and regression analysis (α=0.05). The effect of the desensitizing agents on the dentin surface was examined by scanning electron microscopy. Results: The fluoride-containing desensitizing agents affected the bond strength of the resin-based cements to dentin (p<0.001). PrepEze showed the highest bond strength values in all groups (p<0.001). Conclusion: Regression analysis showed a reverse relation between bond strength values of resin cements to dentin and the amount of fluoride in the desensitizing agent (p<0.05). PMID:19936532

  9. Limitation in obtainable surface roughness of hardened cement paste: 'virtual' topographic experiment based on focussed ion beam nanotomography datasets.

    Science.gov (United States)

    Trtik, P; Dual, J; Muench, B; Holzer, L

    2008-11-01

    Surface roughness affects the results of nanomechanical tests. The surface roughness values to be measured on a surface of a porous material are dependent on the properties of the naturally occurring pore space. In order to assess the surface roughness of hardened cement paste (HCP) without the actual influence of the usual sample preparation for nanomechanical testing (i.e. grinding and polishing), focussed ion beam nanotomography datasets were utilized for reconstruction of 3D (nanoscale resolution) surface profiles of hardened cement pastes. 'Virtual topographic experiments' were performed and root mean square surface roughness was then calculated for a large number of such 3D surface profiles. The resulting root mean square (between 115 and 494 nm) is considerably higher than some roughness values (as low as 10 nm) reported in the literature. We suggest that thus-analysed root mean square values provide an estimate of a 'hard' lower limit that can be achieved by 'artefact-free' sample preparation of realistic samples of hardened cement paste. To the best of our knowledge, this 'hard' lower limit was quantified for a porous material based on hydraulic cement for the first time. We suggest that the values of RMS below such a limit may indicate sample preparation artefacts. Consequently, for reliable nanomechanical testing of disordered porous materials, such as hardened cement paste, the preparation methods may require further improvement.

  10. 水泥基不燃性轻质保温材料制备的研究%Study on the preparation of cement based nonflammable lightweight thermal insulation material

    Institute of Scientific and Technical Information of China (English)

    秦璜; 潘志华; 吕钦刚

    2012-01-01

    A foamed concrete, made from cement as its main component and with its density less than 300 kg/m3 is a novel insulation material for exterior wall. The preparation method of this material was studied in the laboratory with Portland cement as its main raw material, and the influence of some chemical admixtures on the preparation process and the properties of the resultant material were carried in laboratory systematically. Results show that high performance and low density foamed concrete can be prepared with Portland cement as its main raw material and with aid of proper addition of some chemical admixtures> among which the appropriate dosage of the chemical admixtures are as follows: strengthening agent 1.8%,setting accelerator0.8%.polypropylene fiber 0.8%~1.0%,hydrophobic agent 0.1%~0.2% and styrene-acrylic emulsion 0.3%~0.4%. Foamed concrete with dry density 290 kg/m3 prepared under that optimum condition presents its 28 day age compressive strength 1.1 MPa,water absorption rate 6.11% and thermal conductivity 9.07 W/(m·K).%以水泥为主要原料制成的密度小于300 kg/m3的泡沫混凝土,是一种新型外墙外保温材料.采用硅酸盐水泥为主要原料在实验室研究了这种材料的制备方法,并系统地研究了几种混凝土外加剂对该材料制备过程及其性能的影响.结果表明,以硅酸盐水泥为主要原料,并适量添加适宜的混凝土外加剂,可以制得性能优良的低密度泡沫混凝土:其中,几种外加剂的适宜掺量分别为:早强剂1.8%,促凝剂0.8%;聚丙烯纤维0.8%~1.0%:憎水剂0.1%-0.2%,苯丙乳液0.3%~0.4%.在此最佳条件下制得泡沫混凝土的干密度为290 kg,/m3,28 d抗压强度可达1.1 MPa,吸水率为6.11%,导热系数为0.07 W/(m·K).

  11. Development of Advanced Cement-Based Building Products

    Institute of Scientific and Technical Information of China (English)

    Zongjin LI; Bin MU; Stanley N.C.CHIU

    2000-01-01

    @@ In this study, short fiber-reinforced cement-based building products of sheets, pipes and honeycomb panels incorporating various mineral admixtures such as slag, silica fume, and metakaolin have been developed by the extrusion technique. The experimental works have shown that these products do have very good mechanical properties. Since the key point for a successful extrusion is the properly designed rheology which controls both internal and external flow properties of ext rudate, a nonlinear viscoelastic model was applied to investigate the rheology behavior of a movable fresh cementitious composite in a single screw extruder channel. The theoretical analysis is used to guide the practical manufacturing.

  12. Material characterization in cemented radioactive waste with the associated particle technique

    Science.gov (United States)

    Carasco, C.; Perot, B.; Mariani, A.; El Kanawati, W.; Valkovic, V.; Sudac, D.; Obhodas, J.

    2010-07-01

    The elemental characterization of materials constituting radioactive waste is of great importance for the management of storage and repository facilities. To complement the information brought by gamma or X-ray imaging, the performance of a fast neutron interrogation system based on the associated particle technique (APT) has been investigated by using MCNP simulations and by performing proof-of-principle experiments. APT provides a 3D localisation of the emission of fast neutron induced gamma rays, whose spectroscopic analysis allows to identify the elements present in specific volumes of interest in the waste package. Monte Carlo calculations show that it is possible to identify materials enclosed behind the thick outer envelop of a ≈1 m 3 cemented waste drum, provided the excited nuclei emit gamma rays with a sufficient energy to limit photon attenuation. Neutron attenuation and scattering are also predominant effects that reduce the sensitivity and spatial selectivity of APT, but it is still possible to localise items in the waste by neutron time-of-flight and gamma-ray spectroscopy. Experimental tests confirm that the elemental characterization is possible across thick mortar slabs.

  13. Environmental Assessment of Different Cement Manufacturing Processes Based on Emergy and Ecological Footprint Analysis

    Science.gov (United States)

    Due to its high environmental impact and energy intensive production, the cement industry needs to adopt more energy efficient technologies to reduce its demand for fossil fuels and impact on the environment. Bearing in mind that cement is the most widely used material for housin...

  14. Synergistic effects of chemical admixtures in concretes containing supplementary cementing materials

    Energy Technology Data Exchange (ETDEWEB)

    Mailvaganam, N. P. [National Research Council of Canada, Instiute for Research in Construction, Ottawa, ON (Canada)

    2001-07-01

    As a result of the need to produce more durable structures, chemical additives to concrete such as superplasticizers and supplementary cementing materials such as silica fume and fly ash, attract considerable interest. The combined use of these materials produces a synergistic effect which results in a range of modifications such as improved mobility, cohesiveness, ultimate strength and durability, making it possible to place highly durable concrete under a variety of conditions. This paper examines the role of additives in augmenting desirable features in fly ash or silica fume/portland cement mixes, using specific examples to illustrate the manner in which these admixtures compensate for limitations and increase the effectiveness of both of these supplementary cementing materials. Rheological, structural and durability characteristics are the focus of interest. Results show that admixtures influence both the hydration and packing efficiency in the fly ash or silica fume concrete, producing significant improvements in the concrete that could not be readily attained if the materials were used individually. 30 refs., 3 tabs., 9 figs.

  15. Eugenol-based temporary luting cement possesses antioxidative properties

    Directory of Open Access Journals (Sweden)

    Ilić Dragan

    2014-01-01

    Full Text Available Introduction. Antioxidants protect against reactive oxygen species and expose beneficial anti-inflammatory activity when in contact with biological tissues. Dental materials that are used as temporary luting on fixed dental restorations are often in contact with injured gingival tissue, hence they should contain anti-inflammatory characteristics that are essential after prosthetic procedures preceding cementation of final restauration. Objective. The aim of this study was to investigate the antioxidant effect through the oxidation inhibition (OI of mixed dental cement for temporary luting or their liquid component. Methods. Eight study groups were prepared each by ten samples: 1 ex tempore preparation of zinc-oxide eugenol paste (Kariofil Z Galenika, Serbia, 2 Viko Temp paste (Galenika, Serbia, 3 Temp Bond NE paste (Kerr, Germany, 4 ScutaBond (ESPE, Germany, 5 Cp-CAP paste (Germany, Lege Artis and oil component of 6 Kariofil Z, 7 Viko Temp and 8 Cp-CAP. The samples were subjected to spectrophotometer to measure OI 2,2’-azino-di-(3-ethyl-benzthiazoline-6-sulphonic acid (ABTS using Randox kit, United Kingdom. The control samples were pure ascorbic acid (1% w/v. Results. High values of OI exposed materials (groups 1, 5, 6, 7, 8 with content of eugenol (or its derivates in the range of 100-88.8% were statistically more significant than the values of non-eugenol substances (groups 2, 3, 4 with the range of 8.2-43.5%. Conclusion. Eugenol containing temporary fixation materials show significant antioxidative properties and therefore they may be used in those clinical situations where surrounding gingival tissue is injured during restorative procedure. [Projekat Ministarstva nauke Republike Srbije, br. III 45005

  16. In vitro degradation and in vivo resorption of dicalcium phosphate cement based grafts.

    Science.gov (United States)

    Sheikh, Zeeshan; Zhang, Yu Ling; Grover, Liam; Merle, Géraldine E; Tamimi, Faleh; Barralet, Jake

    2015-10-01

    There are two types of DCP: dihydrated (brushite) and anhydrous (monetite). After implantation, brushite converts to hydroxyapatite (HA) which resorbs very slowly. This conversion is not observed after implantation of monetite cements and result in a greater of resorption. The precise mechanisms of resorption and degradation however of these ceramics remain uncertain. This study was designed to investigate the effect of: porosity, surface area and hydration on in vitro degradation and in vivo resorption of DCP. Brushite and two types of monetite cement based grafts (produced by wet and dry thermal conversion) were aged in phosphate buffered saline (PBS) and bovine serum solutions in vitro and were implanted subcutaneously in rats. Here we show that for high relative porosity grafts (50-65%), solubility and surface area does not play a significant role towards in vitro mass loss with disintegration and fragmentation being the main factors dictating mass loss. For grafts having lower relative porosity (35-45%), solubility plays a more crucial role in mass loss during in vitro ageing and in vivo resorption. Also, serum inhibited dissolution and the formation of HA in brushite cements. However, when aged in PBS, brushite undergoes phase conversion to a mixture of octacalcium phosphate (OCP) and HA. This phase conversion was not observed for monetite upon ageing (in both serum and PBS) or in subcutaneous implantation. This study provides greater understanding of the degradation and resorption process of DCP based grafts, allowing us to prepare bone replacement materials with more predictable resorption profiles.

  17. Piezoresistivity in Carbon Fiber Reinforced Cement Based Composites

    Institute of Scientific and Technical Information of China (English)

    Bing CHEN; Keru WU; Wu YAO

    2004-01-01

    The resu lts of some i nteresti ng investigation on the piezoresistivity of ca rbon fi ber reinforced cement based com posites (CFRC) are presented with the prospect of developing a new nondestructive testing method to assess the integrity of the composite. The addition of short carbon fibers to cement-based mortar or concrete improves the structural performance and at the same time significantly decreases the bulk electrical resistivity. This makes CFRC responsive to the smart behavior by measuring the resistance change with uniaxial pressure. The piezoresistivity of CFRC under different stress was studied, at the same time the damage occurring inner specimens was detected by acoustic emission as well. Test results show that there exists a marking pressure dependence of the conductivity in CFRC, in which the so-called negative pressure coefficient of resistive (NPCR) and positive pressure coefficient of resistive (PPCR) are observed under low and high pressure. Under constant pressures, time-dependent resistivity is an outstanding characteristic for the composites, which is defined as resistance creep. The breakdown and rebuild-up process of conductive network under pressure may be responsible for the pressure dependence of resistivity.

  18. Using Neutron Radiography to Quantify Water Transport and the Degree of Saturation in Entrained Air Cement Based Mortar

    Science.gov (United States)

    Lucero, Catherine L.; Bentz, Dale P.; Hussey, Daniel S.; Jacobson, David L.; Weiss, W. Jason

    Air entrainment is commonly added to concrete to help in reducing the potential for freeze thaw damage. It is hypothesized that the entrained air voids remain unsaturated or partially saturated long after the smaller pores fill with water. Small gel and capillary pores in the cement matrix fill quickly on exposure to water, but larger pores (entrapped and entrained air voids) require longer times or other methods to achieve saturation. As such, it is important to quantitatively determine the water content and degree of saturation in air entrained cementitious materials. In order to further investigate properties of cement-based mortar, a model based on Beer's Law has been developed to interpret neutron radiographs. This model is a powerful tool for analyzing images acquired from neutron radiography. A mortar with a known volume of aggregate, water to cement ratio and degree of hydration can be imaged and the degree of saturation can be estimated.

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

    OpenAIRE

    2006-01-01

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

  20. BLENDED CALCIUM ALUMINATE-CALCIUM SULFATE CEMENT-BASED GROUT FOR P-REACTOR VESSEL IN-SITU DECOMMISSIONING

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C.; Stefanko, D.

    2011-03-10

    The objective of this report is to document laboratory testing of blended calcium aluminate - calcium hemihydrate grouts for P-Reactor vessel in-situ decommissioning. Blended calcium aluminate - calcium hemihydrate cement-based grout was identified as candidate material for filling (physically stabilizing) the 105-P Reactor vessel (RV) because it is less alkaline than portland cement-based grout which has a pH greater than 12.4. In addition, blended calcium aluminate - calcium hemihydrate cement compositions can be formulated such that the primary cementitious phase is a stable crystalline material. A less alkaline material (pH {<=} 10.5) was desired to address a potential materials compatibility issue caused by corrosion of aluminum metal in highly alkaline environments such as that encountered in portland cement grouts [Wiersma, 2009a and b, Wiersma, 2010, and Serrato and Langton, 2010]. Information concerning access points into the P-Reactor vessel and amount of aluminum metal in the vessel is provided elsewhere [Griffin, 2010, Stefanko, 2009 and Wiersma, 2009 and 2010, Bobbitt, 2010, respectively]. Radiolysis calculations are also provided in a separate document [Reyes-Jimenez, 2010].

  1. Preparation of lunar regolith based geopolymer cement under heat and vacuum

    Science.gov (United States)

    Davis, Gabrielle; Montes, Carlos; Eklund, Sven

    2017-04-01

    Ever since the beginning of the space program, lunar habitation has always been on peoples' minds. Prior researchers have explored habitat building materials - some based on earth-based construction materials, some based on in-situ lunar resources. Geopolymer cement is a cementitious binder made of aluminosilicate materials such as lunar regolith. A cementitious binder made of lunar regolith as the main geopolymer precursor, instead of as an added aggregate, is a solution that has not been deeply explored in prior works. This research explores the curing process of lunar regolith based geopolymer cement in an environment that loosely approximates the lunar environment, using the lunar average daytime temperature and a vacuum. The results did not show much promise for the samples cured under both heat and vacuum as the longest-cured data point did not meet compressive strength standards, but another pathway to lunar habitation may be found in a separate set of samples that cured under heat and ambient atmospheric pressure.

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

    Directory of Open Access Journals (Sweden)

    Janneth Torres Agredo

    2014-03-01

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

  3. Severe particulate pollution from deposition practices of primary materials of cement plants

    Science.gov (United States)

    Kourtidis, Konstantinos; Rapsomanikis, Spyridon; Zerefos, Christos; Georgoulias, Aristeidis; Pavlidou, Eleni

    2014-05-01

    Analysis of ambient particulates sampled at a residential area near a cement manufacturing plant in Greece, showed total aerosol mass in the sampled air 1.3-30.4 mg/m3 and PM10 concentrations 0.04-3 mg/m3. These concentrations are very high and seriously exceed air quality standards. Morphological examination and elemental analysis of air samples and primary materials with Scanning Electron Microscopy (SEM)/Energy Dispersive X-Ray Spectroscopy (EDS) showed that ambient particulates shared appearance features and had similar elemental synthesis to clinker and fly ash, showing heavy impacts on the ambient aerosol load from the cement plant practice of open deposition of primary materials. Satellite-derived AOD over the area during the period 2000-2010 shows extended spatial impact, while satellite overpass data indicate a 33% decrease in AOD over this period, possibly due to changing production and primary material deposition practices. Although the sampling was performed more than one decade ago in Greece, environmental legislation and its reinforcement practices at that time in Greece are similar to current ones in many parts of the world. The global increase in cement production, especially in south-east Asia, make these measurements particularly relevant.

  4. Pore Distribution and Water Uptake in a Cenosphere-Cement Paste Composite Material

    Science.gov (United States)

    Baronins, J.; Setina, J.; Sahmenko, G.; Lagzdina, S.; Shishkin, A.

    2015-11-01

    Alumina silicate cenospheres (CS) is a significant waste material from power plants that use a coal. Use CS as Portland cement replacement material gives opportunity to control physical and mechanical properties and makes a product lighter and more cost-effective. In the frame of this study, Portland cement paste samples were produced by adding CS in the concentration range from 0 to 40 volume %. Water uptake of hardened samples was checked and pore size distribution by using the mercury porosimetry was determined. In a cold climate where the temperature often falls below 0 °C, it is important to avoid the amount of micrometer sized pores in the final structure and to decrease water absorption capacity of material. In winter conditions, water fills such pores and causes additional stresses to their walls by expansion while freezing. It was found that generally water uptake capacity for cement paste samples decreased up to 20% by increasing the concentration of CS up to 40 volume %, at the same time, the volume of micrometer sized opened pores increases.

  5. Alternative cementing materials for completion of deep, hot oil wells; Sementeringsmateriale med regulert herdetid, for anvendelse i dype, varme oljebroenner

    Energy Technology Data Exchange (ETDEWEB)

    Justnes, H.; Dahl-Joergensen, E.

    1995-03-06

    The invention deals with alternative cementing materials for use in oil well completion. A cementing material with controlled curing time, for use in the primary secondary cementing of deep hot oil wells with a static background temperature in the range of 120 to 200{sup o}C, comprising a resin consisting of ortho-, meta- and/or para-diallyl phthalates and/or prepolymers and/or oligomers thereof; a curing agent in the form of a dissolved organic peroxide generating free radicals, and an inhibitor for stabilizing free radicals so as to obtain the required open time for pumping the resin in place, and optionally the following, one or more heavy weight filler(s) for controlling the density of the cement; extender materials controlling the consistency and materials compensating inherent shrinkage. 6 figs.

  6. 水泥基整体防水复合材料在弯曲应力作用下渗透性研究%Study on the permeability of cement-based materials addition of silane emulsion under crack environment

    Institute of Scientific and Technical Information of China (English)

    赵炜; 马志鸣; 黄巍林

    2014-01-01

    It was prepared within the cement-based materials specimen addition with silane emulsion.Through the four-point bending test,the specimen was measured at different stress,different strain resistant to water resistance.The result shows that the cement-based ma-terials specimen addition with silane emulsions have a good performance on penetration resistance compared with the blank sample.Even though under the high strain environment,the sample could resistance to water penetration,which promotes the durability of the concrete.%向水泥基复合材料中添加硅烷乳液制备整体防水试件,通过四点弯曲试验,测定试件在不同应力、应变的多缝开裂环境下抗水渗透性能。试验结果表明:对比未掺入硅烷乳液的空白试件,水泥基整体防水试件具有良好的抗水渗透性能,即使在较高的应变环境下,仍能有效的抵抗水分的侵入,从而提高了试件的耐久性能。

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

    OpenAIRE

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

    2013-01-01

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

  8. Hybrid Polyvinyl Alcohol and Cellulose Fiber Pulp Instead of Asbestos Fibers in Cement-Based Composites

    Science.gov (United States)

    Shokrieh, M. M.; Mahmoudi, A.; Shadkam, H. R.

    2015-05-01

    The Taguchi method was used to determine the optimum content of a four-parameters cellulose fiber pulp, polyvinyl alcohol (PVA) fibers, a silica fume, and bentonite for cement-based composite sheets. Then cement composite sheets from the hybrid of PVA and the cellulose fiber pulp were manufactured, and their moduli of rapture were determined experimentally. The result obtained showed that cement composites with a hybrid of PVA and cellulose fiber pulp had a higher flexural strength than cellulose-fiber- reinforced cement ones, but this strength was rather similar to that of asbestos-fiber-reinforced cement composites. Also, using the results of flexural tests and an analytical method, the tensile and compressive moduli of the hybrid of PVA and cement sheet were calculated. The hybrid of PVA and cellulose fiber pulp is proposed as an appropriate alternative for substituting asbestos in the Hatschek process.

  9. Asphalt cement poisoning

    Science.gov (United States)

    ... petroleum material that hardens when it cools. Asphalt cement poisoning occurs when someone swallows asphalt. If hot ... found in: Road paving materials Roofing materials Tile cements Asphalt may also be used for other purposes.

  10. Dynamic intratubular biomineralization following root canal obturation with pozzolan‐based mineral trioxide aggregate sealer cement

    Science.gov (United States)

    Yoo, Yeon‐Jee; Baek, Seung‐Ho; Kum, Kee‐Yeon; Shon, Won‐Jun; Woo, Kyung‐Mi

    2015-01-01

    Summary The application of mineral trioxide aggregates (MTA) cement during the root canal obturation is gaining concern due to its bioactive characteristic to form an apatite in dentinal tubules. In this regard, this study was to assess the biomineralization of dentinal tubules following root canal obturation by using pozzolan‐based (Pz‐) MTA sealer cement (EndoSeal MTA, Maruchi). Sixty curved roots (mesiobuccal, distobuccal) from human maxillary molars were instrumented and prepared for root canal obturation. The canals were obturated with gutta‐percha (GP) and Pz‐MTA sealer by using continuous wave of condensation technique. Canals obturated solely with ProRoot MTA (Dentsply Tulsa Dental) or Pz‐MTA sealer were used for comparison. In order to evaluate the biomineralization ability under different conditions, the PBS pretreatment before the root canal obturation was performed in each additional samples. At dentin‐material interfaces, the extension of intratubular biomineralization was analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy. When the root canal was obturated with GP and Pz‐MTA sealer, enhanced biomineralization of the dentinal tubules beyond the penetrated sealer tag was confirmed under the SEM observation (p cement can be used as a promising bioactive root canal sealer to enhance biomineralization of dentinal tubules under controlled environment. SCANNING 38:50–56, 2016. © 2015 The Authors. Scanning Published by Wiley Periodicals, Inc. PMID:26179659

  11. Dynamic intratubular biomineralization following root canal obturation with pozzolan-based mineral trioxide aggregate sealer cement.

    Science.gov (United States)

    Yoo, Yeon-Jee; Baek, Seung-Ho; Kum, Kee-Yeon; Shon, Won-Jun; Woo, Kyung-Mi; Lee, WooCheol

    2016-01-01

    The application of mineral trioxide aggregates (MTA) cement during the root canal obturation is gaining concern due to its bioactive characteristic to form an apatite in dentinal tubules. In this regard, this study was to assess the biomineralization of dentinal tubules following root canal obturation by using pozzolan-based (Pz-) MTA sealer cement (EndoSeal MTA, Maruchi). Sixty curved roots (mesiobuccal, distobuccal) from human maxillary molars were instrumented and prepared for root canal obturation. The canals were obturated with gutta-percha (GP) and Pz-MTA sealer by using continuous wave of condensation technique. Canals obturated solely with ProRoot MTA (Dentsply Tulsa Dental) or Pz-MTA sealer were used for comparison. In order to evaluate the biomineralization ability under different conditions, the PBS pretreatment before the root canal obturation was performed in each additional samples. At dentin-material interfaces, the extension of intratubular biomineralization was analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy. When the root canal was obturated with GP and Pz-MTA sealer, enhanced biomineralization of the dentinal tubules beyond the penetrated sealer tag was confirmed under the SEM observation (p cement can be used as a promising bioactive root canal sealer to enhance biomineralization of dentinal tubules under controlled environment.

  12. Effect of physicochemical properties of a cement based on silicocarnotite/calcium silicate on in vitro cell adhesion and in vivo cement degradation.

    Science.gov (United States)

    Aparicio, Julia Lucas; Rueda, Carmen; Manchón, Ángel; Ewald, Andrea; Gbureck, Uwe; Alkhraisat, Mohammad Hamdan; Jerez, Luis Blanco; Cabarcos, Enrique López

    2016-08-02

    A silicon calcium phosphate cement (Si-CPC) was developed to produce a composite of calcium phosphate and calcium silicate. The silicon cements prepared with low silicon (Si) content were composed of crystalline phases of brushite and silicocarnotite. However, the cements prepared with high Si content were mainly composed of amorphous phases of silicocarnotite, hydroxyapatite and calcium silicate. The cement porosity was about 40% with a shift of the average pore diameter to the nanometric range with increasing Si content. Interestingly, this new cement system provides a matrix with a high specific surface area of up to 29 m(2) g(-1). The cytocompatibility of the new Si-doped cements was tested with a human osteoblast-like cell line (MG-63) showing an enhancement of cell proliferation (up to threefold) when compared with unsubstituted material. Cements with a high silica content also improved the cell attachment. The in vivo results indicated that Si-CPCs induce the formation of new bone tissue, and modify cement resorption. We conclude that this cement provides an optimal environment to enhance osteoblast growth and proliferation that could be of interest in bone engineering.

  13. [Development and evaluation of fertilizers cemented and coated with organic-inorganic materials].

    Science.gov (United States)

    Xiao, Qiang; Wang, Jia-Chen; Zuo, Qiang; Zhang, Lin; Liu, Bao-Cun; Zhao, Tong-Ke; Zou, Guo-Yuan; Xu, Qiu-Ming

    2010-01-01

    Four kinds of organic-inorganic cementing and coating materials were prepared by a coating method using water as the solvent, and the corresponding cemented and coated fertilizers (B2, PS, F2, and F2F) were produced by disc pelletizer. The tests on the properties of these fertilizers showed that the granulation rate, compression strength, and film-forming rate were B2 > PS > F2 > F2F. Soil column leaching experiment showed that the curve of accumulated nitrogen-dissolving rate was the gentlest for B2. In 48 days, the accumulated nitrogen-dissolving rate was in the order of B2, 54.65% fertilizers had better effects on corn yield, among which, B2 was the best, with the corn yield and fertilizer use efficiency increased by 19.72% and 20.30%, respectively. The yield-increasing effect of other test fertilizers was in the order of PS > F2 > F2F.

  14. Interaction between pollutants produced in sewage sludge combustion and cement raw material.

    Science.gov (United States)

    Gálvez, Araceli; Conesa, Juan A; Martín-Gullón, Ignacio; Font, Rafael

    2007-09-01

    Nowadays the use of waste as secondary fuel in clinker kilns is an extensive practice, but the interaction between cement raw material (CRM) and the combustion gases of the fuels has not been extensively studied. Because of that, in this work the effect of the interaction of exhaust from the combustion of sewage sludge and CRM has been studied in a laboratory furnace. The experiments were performed at 300 degrees C, close to the temperature at the cyclones in a cement industry. The behavior of volatile compounds, polycyclic aromatic compounds (PAH) and polychloro dibenzo-p-dioxin and polychloro dibenzofurans (PCCD/F) were analysed in the presence or absence of CRM. The results obtained show that the presence of CRM at the outlet of the combustion gases is beneficial for the decrease of pollutant emissions.

  15. Development of Mechanistic-Empirical Pavement Design for Tropical Climate Using Cement-Treated Base Layer

    Directory of Open Access Journals (Sweden)

    O. S. Aderinola

    2016-08-01

    Full Text Available A mechanistic-empirical pavement design method is developed characterising cement-treated base layers for pavement design in Nigeria or other similar tropical and subtropical countries. Asphalt Concrete surface, Subbase and Aggregate base were characterised based on back calculation data from Claros et al (1986 while cement-treated base layer was based on modulus tests that had been conducted by past researchers. Failure criteria for the Asphalt Concrete fatigue failure and the subgrade rutting failure were based on those by Claros and Ijeh (1987 for Nigerian pavements. Cracking criterion used for the cement-treated layer was that developed by Otee et al. (1982. The comparison between the Soil-Cement and Aggregate base showed that at a low Equivalent Single Axle Load (ESAL (0.5 million repetitions was considered, the use of Aggregate base was better than Soil-Cement base. That for Aggregate base and Cement-Treated Gravel Base showed that the Cement-Treated Gravel Base was better than the Aggregate base at high ESAL (2.5 million repetitions was considered

  16. Microstructure of a Planting Material Consisting of Nutrition-Expansive Perlitic-Cement Composites

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ji-ru; LIU Zu-de

    2003-01-01

    An ecotypic revetment material consisting of nutrition-expansive perlitic-cement composites is introduced. This planting material can combine vegetation recovery with slope protection. The XRD, SEM and image analysis techniques were used to study its composition and microstructure. Its strength was measured by an electro-hydraulic servo-controlled testing machine. The results show the unconfined compressive strength is about 393.6 kPa, and the average elastic modulus is about 47.0 MPa. The quartz, felspar, chlorite and calcite are the main non-clay minerals in the planting material. Its particles are mainly spherical,and the range of the equivalent diameter is 1.83 to 15.96 μm. The results also show the planting material contains a large amount of micro non-capillary and capillary pores, and has a microstructure characteristic of honeycomb and coralline. CSH gel produced by hydration of cement increases the strength and water stability of the particles. The anisotropy and slight orientation of the particles increase the void cross-section area,providing an explanation of the high permeability for the planting material.The better porosity of the planting material is apt tokeep moisture and nutriment, provides oxygen for plant root breathing, and aids to exhaust the carbon dioxide by means of exchanging with atmosphere, hence it can facilitate vegetation.

  17. ASHES AS AN AGENT FOR CEMENT-LIME BASED SOLIDIFICATION/STABILIZATION OF THE HAZARDOUS WASTE

    Directory of Open Access Journals (Sweden)

    Barbora Lyčkova

    2008-12-01

    Full Text Available One of the common treatment methods for the hazardous waste is the cement and cement-lime based solidification/stabilization (S/S. This article deals with the possibility of currently used recipe modification using fluidized bed heating plant ashes as an agent.

  18. Synthesis of partial stabilized cement-gypsum as new dental retrograde filling material

    Energy Technology Data Exchange (ETDEWEB)

    Sadhasivam, S. [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Division of Medical Engineering Research, National Health Research Institute, Zhunan, Miaoli County, Taiwan (China); Chen, Jung-Chih [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Medical Device Innovation Center, National Cheng Kung University, Tainan,Taiwan (China); Savitha, S. [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Hsu, Ming-Xiang; Hsu, Chung-King [Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei, Taiwan (China); Lin, Chun-Pin [School of Dentistry and Graduate Institute of Clinical Dentistry, College of Medicine, National Taiwan University and National Taiwan University Hospital, Taipei, Taiwan (China); Lin, Feng-Huei, E-mail: double@ntu.edu.tw [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Division of Medical Engineering Research, National Health Research Institute, Zhunan, Miaoli County, Taiwan (China)

    2012-10-01

    The study describes the sol-gel synthesis of a new dental retrograde filling material partial stabilized cement (PSC)-gypsum by adding different weight percentage of gypsum (25% PSC + 75% gypsum, 50% PSC + 50% gypsum and 75% PSC + 25% gypsum) to the PSC. The crystalline phase and hydration products of PSC-gypsum were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. The handling properties such as setting time, viscosity, tensile strength, porosity and pH, were also studied. The XRD and microstructure analysis demonstrated the formation of hydroxyapatite and removal of calcium dihydrate during its immersion in simulated body fluid (SBF) on day 10 for 75% PSC + 25% gypsum. The developed PSC-gypsum not only improved the setting time but also greatly reduced the viscosity, which is very essential for endodontic surgery. The cytotoxic and cell proliferation studies indicated that the synthesized material is highly biocompatible. The increased alkaline pH of the PSC-gypsum also had a remarkable antibacterial activity. - Highlights: Black-Right-Pointing-Pointer A new dental retrograde filling material PSC-gypsum was developed. Black-Right-Pointing-Pointer PSC-gypsum cement has shown excellent initial and final setting time as 15-35 min. Black-Right-Pointing-Pointer It not only improved the setting time but also retain the viscosity, 2 Pa{center_dot}s. Black-Right-Pointing-Pointer High alkaline pH of the cement had a remarkable antibacterial activity. Black-Right-Pointing-Pointer Cytotoxicity studies revealed that the synthesized material is highly biocompatible.

  19. Effect of Material Ion Exchanges on the Mechanical Stiffness Properties and Shear Deformation of Hydrated Cement Material Chemistry Structure C-S-H Jennit - A Computational Modeling Study

    Science.gov (United States)

    2014-01-01

    and high versatility, cement has remained the most widely utilized material in the world [2]. The starting material of cement is the clinker phase...things of God. v Dedication This work is dedicated to God almighty the giver of life and strength . It is also dedicated to my parents Mr...Jennite Structures (% Weight) ................................................ 34 Table 5 Shear Modulus, Strength and Maximum Shear Deformation of cb

  20. Development of Mechanistic-Empirical Pavement Design for Tropical Climate Using Cement-Treated Base Layer

    OpenAIRE

    Aderinola, O.S

    2016-01-01

    A mechanistic-empirical pavement design method is developed characterising cement-treated base layers for pavement design in Nigeria or other similar tropical and subtropical countries. Asphalt Concrete surface, Subbase and Aggregate base were characterised based on back calculation data from Claros et al (1986) while cement-treated base layer was based on modulus tests that had been conducted by past researchers. Failure criteria for the Asphalt Concrete fatigue failure and the s...

  1. Potential Use Of Carbide Lime Waste As An Alternative Material To Conventional Hydrated Lime Of Cement-Lime Mortars

    OpenAIRE

    Al Khaja, Waheeb A.

    1992-01-01

    The present study aimed at the possibility of using the carbide lime waste as an alternative material to the conventional lime used for cement-lime mortar. The waste is a by-product obtained in the generation of acetylene from calcium carbide. Physical and chemical properties of the wastes were studied. Two cement-lime-sand mix proportions containing carbide lime waste were compared with the same mix proportions containing conventional lime along with a control mix without lime. Specimens wer...

  2. Comparison of the sealing ability of two root-end filling materials (MTA and CEM cement following retropreparation with ultrasonic or Er,Cr:YSGG laser

    Directory of Open Access Journals (Sweden)

    Razmi H

    2010-01-01

    Full Text Available "nBackground and Aims: Considering advantages and disadvantages of mineral trioxide aggregate (MTA, Calcium Enriched Mixture (CEM cement has been developed recently. The purpose of this study was to compare the apical microleakage of the root-end cavities prepared by ultrasonic or Er,Cr:YSGG laser and filled with MTA or CEM cement. "nMaterials and Methods: Eighty single-rooted, extracted human teeth were instrumented and obturated. Root-end resection was made by removing 3 mm of the apex. The teeth were randomly divided into two experimental (n=30 and two positive and negative control (n=10 groups. After that, the retrograde cavities were prepared using ultrasonic or Er,Cr: YSGG Laser. According to the root-end filling materials (MTA or CEM cement, each group was then divided into two subgroups. Finally, specimens were cleared for assessing the amount of apical dye (Indian ink penetration. The data were analyzed using Kruskall-Wallis and Dunn tests. "nResults: Laser/CEM cement group showed significantly the lowest mean apical dye penetration. There were no statistically significant differences between Laser/MTA, ultrasonic/MTA and ultrasonic/CEM cement groups. "nConclusion: Based on the findings of this study, CEM cement demonstrated lower rate of apical leakage compared with MTA, when the root-end cavities prepared with Er,Cr:YSGG Laser. The sealing ability of MTA was not different following root-end preparation by ultrasonic or Er,Cr:YSGG Laser.

  3. Evaluation of sealing ability of two temporary resin-based cements used in Endodontics

    Directory of Open Access Journals (Sweden)

    Paloma Mariana Ramos Bitencourt

    2010-07-01

    Full Text Available Introduction: The outcome of endodontic treatment is related to the sealing ability of temporary dental restoration, which aims to prevent bacterial infiltration and recontamination of the root canal system.Objective: The purpose of this study was to evaluate the sealing ability of two temporary resin-based cements: Fill Magic Tempo and Bioplic.Material and methods: Twenty-four third molars were used, and twenty-two of them were opened to the pulp chamber (resulting in a class I cavity and randomly divided: group 1 was restored using Fill Magic Tempo (n = 10 and group 2 was restored using Bioplic (n = 10.The negative control group was not opened (n = 2, and the positive control group was opened but not restored (n = 2. Then the root and apex of the teeth were varnished to become impermeable. All samples were immersed in 2% methylene blue and kept at 37°C for 72h.After longitudinal sectioning, the linear leakage was measured in mm.In sequence, the statistical analysis was performed using Mann-Whitney test with a level of significance of 5%. Results: Most part of the samples showed leakage of 1 mm, and only the negative control group showed total leakage. There was no significant difference between the tested materials. Conclusion: It is possible to conclude that both resin-based cements showed satisfactory results on sealing ability during endodontic treatment.

  4. Development programs in the United States of America for the application of cement-based grouts in radioactive waste management

    Energy Technology Data Exchange (ETDEWEB)

    Dole, L.R.; Row, T.H.

    1984-01-01

    This paper briefly reviews seven cement-based waste form development programs at six of the US Department of Energy (DOE) sites. These sites have developed a variety of processes that range from producing 25 mm (1 in.) diameter pellets in a glove box to producing 240 m (800 ft.) diameter grout sheets within the bedding planes of a deep shale formation. These successful applications of cement-based waste forms to the many radioactive waste streams from nuclear facilities bear witness to the flexibility and reliability of this class of materials. This paper also discusses the major issues regarding the application of cement-based waste forms to radioactive waste management problems. These issues are (1) leachability, (2) radiation stability, (3) thermal stability, (4) phase complexity of the matrix, and (5) effects of the waste stream composition. A cursory review of current research in each of these areas is given This paper also discusses future trends in cement-based waste form development and applications. 31 references, 11 figures.

  5. Cementing Material From Rice Husk-Broken Bricks-Spent Bleaching Earth-Dried Calcium Carbide Residue

    Directory of Open Access Journals (Sweden)

    Muthengia Jackson Washira

    2012-10-01

    Full Text Available A cementious material, coded CSBR (Carbide residue Spent bleaching earth Broken bricks and Rice husks, was made from dried calcium carbide residue (DCCR and an incinerated mix of rice husks (RH, broken bricks (BB and spent bleaching earth (SBE. Another material, coded SBR (Spent bleaching earth Broken bricks and Rice husk ash, was made from mixing separately incinerated RH, SBE and ground BB in the same ash ratio as in CSBR. When CSBR was inter-ground with Ordinary Portland Cement (OPC, it showed a continued decrease in Ca(OH2 in the hydrating cement as a function of curing time and replacement levels of the cement. Up to 45 % replacement of the OPC by CSBR produced a Portland pozzolana cement (PPC material that passed the relevant Kenyan Standard. Incorporation of the CSBR in OPC reduces the resultant calcium hydroxide from hydrating Portland cement. The use of the waste materials in production of cementitious material would rid the environment of wastes and lead to production of low cost cementitious material.

  6. 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.

  7. Comparison of the fixation effects of heavy metals by cement rotary kiln co-processing and cement based solidification/stabilization.

    Science.gov (United States)

    Zhang, Junli; Liu, Jianguo; Li, Cheng; Jin, Yiying; Nie, Yongfeng; Li, Jinhui

    2009-06-15

    Cement rotary kiln co-processing of hazardous wastes and cement based solidification/stabilization could both immobilize heavy metals. The different retention mechanisms of the two technologies lead to different fixation effects of heavy metals. The same amount of heavy metal compounds were treated by the two types of fixation technologies. Long-term leaching test (160 days), the maximum availability leaching test (NEN 7341) and a modified three-step sequential extraction procedure, proposed by the Commission of the European Communities Bureau of Reference (BCR) were employed to compare the fixation effects of the two fixation technologies. The leaching concentrations in NEN 7341 and long-term leaching tests were compared with identification standard for hazardous wastes (GB5085.3-1996) and drinking water standard (GB5749-2005). The results indicate that the leaching concentrations of the long-term leaching test and NEN 7341 test were lower than the regulatory limits and the leached ratios were small. Both cement based solidification/stabilization and cement rotary kiln co-processing could effectively fix heavy metals. Calcination in a cement rotary kiln and the following hydration that follows during cement application could fix As, Cd, Pb and Zn more effectively and decrease the release to the environment. Cement solidification/stabilization technology has better effect in immobilizing Cr and Ni. Cr wastes are more fitful to be treated by cement solidification/stabilization.

  8. Microstructure and mechanical properties of WC-Ni-Al based cemented carbides developed for engineering applications

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Edmilson O.; Santos, Julio N. [Universidade Federal de Itajuba, Minas Gerais (Brazil). Inst. de Engenharia Mecanica; Klein, Aloisio N. [Universidade Federal de Santa Catarina, Florianopolis (Brazil). Dept. de Engenharia de Materiais

    2011-11-15

    In this paper the influence of the Ni binder metal and Al as an additional alloying element on the microstructure and mechanical properties of WC-based cemented carbides processed by conventional powder metallurgy was studied. Microstructural examinations of the cemented carbides with 3 and 5 wt.% of Al in the binder metal indicated the presence of a very low and evenly distributed porosity as well as the presence of islands of metal binder in the microstructure. With the cemented carbide with 7 wt.% of Al in the metal binder, the presence of brittle needle-like regions was observed. The WC particles inside these regions were rounded and had a larger mean free path. Vickers hardness and flexural strength tests indicated that the cemented carbide WC-Ni - Al with addition of 5 wt.% of Al in the binder metal presented bulk hardness similar to the conventional WC-Co cemented carbides as well as superior flexure strength and fracture toughness. (orig.)

  9. Nanohydroxyapatite Silicate-Based Cement Improves the Primary Stability of Dental Implants: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    Hooman Khorshidi

    2017-01-01

    Full Text Available Objectives. Insufficient cortical bone volume when placing implants can lead to lack of primary stability. The use of cement as a bone fill material in bone defects around dental implant could result in better clinical outcome. HA has shown excellent biological properties in implant dentistry. The purpose of this study was to evaluate the effect of nanohydroxyapatite powder (Nano-HA in combination with accelerated Portland cement (APC on implant primary stability in surgically created circumferential bone defects in a bovine rib in vitro model. Materials and Methods. Sixteen bovine rib bones and thirty-six implants of same type and size (4 mm × 10 mm were used. Implants were divided into six groups: no circumferential bone defect, defect and no grafting, bone chips grafting, Nano-HA grafting, APC grafting, and Nano-HA mixed to APC grafting (Nano-HA-APC. Circumferential defects around the implants were prepared. The implant stability quotient (ISQ values were measured before and after the grafting. Results. APC exhibited the highest ISQ values. A significant increase of ISQ values following the grafting of Nano-HA-APC (18.08±5.82 and APC alone (9.50±4.12 was achieved. Increase of ISQ values after 72 hours was 24.16±5.01 and 17.58±4.89, respectively. Nano-HA grafting alone exhibited the least rise in ISQ values. Conclusions. Nanohydroxyapatite silicate-based cement could improve the primary stability of dental implants in circumferential bone defect around implants.

  10. Preparation of Electrolytic Manganese Residue Composite Cementing Material%电解锰渣复合胶凝材料的研制

    Institute of Scientific and Technical Information of China (English)

    王智; 高翠翠; 王庆珍

    2013-01-01

    Electrolytic manganese residue and calcined lime were used to stimulate the activity of the pozzolanic material of fly ash,and electrolytic manganese residue composite cementing material was researched and developed.The influence of electrolytic manganese residue and cement to composite cementing material was studied,and based on this,the optimal mix proportion was concluded.When the mass ratio of electrolytic manganese residue,fly ash,lime and cement was 50 ∶ 30 ∶ 10 ∶ 10,water to binder ratio was 0.55,28 d flexural,compressive strength of electrolytic manganese residue composite cementing material were 2.50 MPa,10.05 MPa.%利用电解锰渣和生石灰激发火山灰质材料粉煤灰的火山灰活性,制备电解锰渣复合胶凝材料.研究了电解锰渣和水泥对复合胶凝材料性能的影响,并在此基础上得出了最佳配合比,当电解锰渣复合胶凝材料中电解锰渣、粉煤灰、生石灰与水泥的质量比为50∶30∶ 10∶10,取水胶质量比为0.55,其28d抗折、抗压强度分别为2.50 MPa、10.05 MPa.

  11. Binding Materials of Dehydrated Phases of Waste Hardened Cement Paste and Pozzolanic Admixture

    Institute of Scientific and Technical Information of China (English)

    LU Linnu; HE Yongjia; HU Shuguang

    2009-01-01

    Fly ash (FA) and ground granulated blast-furnace slag (GGBFS) were added to improve the performances of regenerated binding materials (RBM) which refer to dehydrated phases with rebinding ability of waste hardened cement paste. Flowability tests, compressive strength tests,SEM, TG-DSC, and non-evaporable water content tests were employed to study the performances of the combined binding materials and the interactions between RBM, FA, and GGBFS. Results show that adding FA or GGBFS can improve the workability of RBM paste, and GGBFS has positive effects on strength of RBM. Pozzolanic reactions happen between RBM, FA, and GGBFS. And the activation effect of RBM to FA and GGBFS is superior to that of P.O grade-32.5 cement, especially at earlier ages, because of the high reactive f-CaO existing in RBM. On the advantages of the synergetic effects of RBM and pozzolanic admixtures such as FA and GGBFS, new combined binding materials can be prepared by blending them together.

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

    Science.gov (United States)

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

    2014-03-01

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

  13. Rapid Set Materials for Advanced Spall Repair

    Science.gov (United States)

    2010-08-01

    cement -based polymer- cement mortar and concrete • Magnesium -ammonium- phosphate - cement mortar and concrete • Polymer-based mortar and concrete...material or lodged debris from the joint or crack. • Place a small bead of caulk over the joint or crack. • If using a cement -based repair material, soak...placement equipment immediately after use. • When using cement repair materials, either wet cure or apply curing compound. • Remove the compressible spacer

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

    Directory of Open Access Journals (Sweden)

    Frías, M.

    2005-12-01

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

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

  15. Novel phosphate-based cements for clinical applications

    OpenAIRE

    2012-01-01

    This Thesis aims at the development of two novel families of inorganic phosphate cements with suitable characteristics for clinical applications in hard tissue regeneration or replacement. It is organized in two distinct parts. The first part focuses at the development of silicon-doped a-tricalcium phosphate and the subsequent preparation of a silicon-doped calcium phosphate cement for bone regeneration applications. For this purpose, silicon-doped a-tricalcium phosphate was synthesized b...

  16. Decomposition of paper wastes in presence of ceramics and cement raw material.

    Science.gov (United States)

    Conesa, Juan A; Gálvez, Araceli; Fullana, Andrés

    2008-05-01

    Paper recycling is an environmental important activity that is carried out in all the countries, but during the recycling process a paper waste is produced. Generally these wastes are placed in landfill sites but it is possible to profit it as secondary fuel and raw material in manufacture furnaces. In this work the combustion of the waste papers with cement and ceramic raw material has been studied with the objective to analyse the interaction of these substances with the emitted pollutants like PAHs and PCDD/Fs. The results of the study show that the presence of inorganic material produces an increment in the lighter PAH emission but chlorinated compounds are not affected. The PCDD/F emission level found in the combustion of this waste is quite low compared with other wastes subjected to similar conditions.

  17. Summary report on the development of a cement-based formula to immobilize Hanford facility waste

    Energy Technology Data Exchange (ETDEWEB)

    Gilliam, T.M.; McDaniel, E.W.; Dole, L.R.; Friedman, H.A.; Loflin, J.A.; Mattus, A.J.; Morgan, I.L.; Tallent, O.K.; West, G.A.

    1987-09-01

    This report recommends a cement-based grout formula to immobilize Hanford Facility Waste in the Transportable Grout Facility (TGF). Supporting data confirming compliance with all TGF performance criteria are presented. 9 refs., 24 figs., 50 tabs.

  18. Properties and Mechanism of CFBC Fly Ash-cement based Stabilizers for Lake Sludge

    Institute of Scientific and Technical Information of China (English)

    TANG Hua; LIXiangguo; LI Menglei; SONG Liuqing; WU Zhenjun; XU Haixing

    2012-01-01

    Circulating fluidized bed combustion (CFBC) fly ash was mixed with cement or lime at a different ratio as a stabilizer to stabilize lake sludge.In order to understand the influences of stabilizers on the lake sludge properties,tests unconfined compressive strength,water stability and SEM observation were performed.The experimental results show that with the increase of the curing time,the strength of all the stabilized specimens increase,especially the samples containing cement.The strength of the specimens is decreased with the increasing of the CFBC fly ash/cement ratio,the optimum ratio between CFBC fly ash and cement is 2:3.The water stability of CFBC fly ash-cement based stabilizers is higher than those of cement and lime.Moreover,the lake sludge stabilization mechanism of CFBC fly ash-cement based stabilizers includes gelation and filling of the hydration products,i e,C-S-H gel and the AFt crystal,which act as benders to solidify those particles together and fill in the packing void of the aggregates.

  19. β-Dicalcium silicate-based cement: synthesis, characterization and in vitro bioactivity and biocompatibility studies.

    Science.gov (United States)

    Correa, Daniel; Almirall, Amisel; García-Carrodeguas, Raúl; dos Santos, Luis Alberto; De Aza, Antonio H; Parra, Juan; Delgado, José Ángel

    2014-10-01

    β-dicalcium silicate (β-Ca₂ SiO₄, β-C₂ S) is one of the main constituents in Portland cement clinker and many refractory materials, itself is a hydraulic cement that reacts with water or aqueous solution at room/body temperature to form a hydrated phase (C-S-H), which provides mechanical strength to the end product. In the present investigation, β-C₂ S was synthesized by sol-gel process and it was used as powder to cement preparation, named CSiC. In vitro bioactivity and biocompatibility studies were assessed by soaking the cement samples in simulated body fluid solutions and human osteoblast cell cultures for various time periods, respectively. The results showed that the sol-gel process is an available synthesis method in order to obtain a pure powder of β-C₂ S at relatively low temperatures without chemical stabilizers. A bone-like apatite layer covered the material surface after soaking in SBF and its compressive strength (CSiC cement) was comparable with that of the human trabecular bone. The extracts of this cement were not cytotoxic and the cell growth and relative cell viability were comparable to negative control.

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

    Science.gov (United States)

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

    2016-03-01

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

  1. Lignin-based cement fluid loss control additive

    Energy Technology Data Exchange (ETDEWEB)

    Schilling, P.

    1990-05-22

    This patent describes a hydraulic cement slurry composition. It comprises: a hydraulic cement, and the following expressed as parts by weight per 100 parts of the hydraulic cement, water from about 25 to 105 parts, and from abut 0.5 to 2.5 parts of a compound selected from the group consisting of a sulfonated lignin and a sulfomethylated lignin, wherein the lignin has been sequentially crosslinked by reacting the lignin with a member of the group consisting of formaldehyde and epichlorohydrin and alkoxylated with between about 2 to about 6 moles of a compound selected from the group consisting of ethylene oxide, propylene oxide, butylene oxide and a combination thereof per 1000 g of the lignin.

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

    Science.gov (United States)

    Salaita, Ghaleb N.; Tate, Philip H.

    1998-05-01

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

  3. Improve the performance of coated cemented hip stem through the advanced composite materials.

    Science.gov (United States)

    Hedia, H S; Fouda, N

    2015-01-01

    Design of hip joint implant using functionally graded material (FGM) (advanced composite material) has been used before through few researches. It gives great results regarding the stress distribution along the implant and bone interfaces. However, coating of orthopaedic implants has been widely investigated through many researches. The effect of using advanced composite stem material, which mean by functionally graded stem material, in the total hip replacement coated with the most common coated materials has not been studied yet. Therefore, this study investigates the effect of utilizing these two concepts together; FGM and coating, in designing new stem material. It is concluded that the optimal FGM cemented stem is consisting from titanium at the upper stem layers graded to collagen at a lower stem layers. This optimal graded stem coated with hydroxyapatite found to reduce stress shielding by 57% compared to homogenous titanium stem coated with hydroxyapatite. However, the optimal functionally graded stem coated with collagen reduced the stress shielding by 51% compared to homogenous titanium stem coated with collagen.

  4. Piezoresistive Response Extraction for Smart Cement-based Composites/Sensors

    Institute of Scientific and Technical Information of China (English)

    HAN Baoguo; QIAO Guofu; JIANG Haifeng

    2012-01-01

    A kind of piezoresistive response extraction method for smart cement-based composites/sensors was proposed.Two kinds of typical piezoresistive cement-based composites/sensors were fabricated by respectively adding carbon nanotubes and nickel powders as conductive fillers into cement paste or cement mortar.The variation in measured electrical resistance of such cement-based composites/sensors was explored without loading and under repeated compressive loading and impulsive loading.The experimental results indicate that the measured electrical resistance of piezoresistive cement-based composites/sensors exhibits a two-stage variation trend of fast increase and steady increase with measurement time without loading,and an irreversible increase after loading.This results from polarization caused by ionic conduction in these composites/sensors.After reaching a plateau,the measured electrical resistance can be divided into an electrical resistance part and an electrical capacity part.The piezoresistive responses of electrical resistance part in measured electrical resistance to loading can be extracted by eliminating the linear electrical capacity part in measured electrical resistance.

  5. Maximizing the Sustainability of Cement Utilization in Building Projects through the Use of Greener Materials

    Directory of Open Access Journals (Sweden)

    Mark Bediako

    2016-01-01

    Full Text Available Greener technologies and sustainable developments are currently among the main tools used by many industries in shaping the world for a better future. The construction industry that is known to have numerous negative impact on sustainability is now wide awake on sustainable measures which can aid in reducing its negative impact. In this work, green cement was produced from pyroprocessed clay (PC at 800°C and mixed together with Portland cement. This paper presents both laboratory tests and some field applications of green cement application. Laboratory tests performed included setting times, compressive strength, and shrinkage. Field applications of the green cement are shown. Results from the work showed that well-proportioned greener cement gained strengths between 11% and 30% more than Portland cement at standard curing period of 3, 7, 14, and 28 days. However, in real statistical terms, there was no difference between Portland cement and green cement strength performance. Shrinkage from both total and autogenous tests also showed insignificant differences between the two cements. The study recommends the use of green cements with pozzolanic origin than only Portland cement as a way to maximize sustainability in building projects.

  6. The research of concrete pavement patching material based on magnesium phosphate cement%磷酸盐水泥基普通混凝土路面修补剂的研究

    Institute of Scientific and Technical Information of China (English)

    周启兆; 焦宝祥; 丁胜; 刘孝江; 蔡玉斌; 成扬

    2011-01-01

    A kind of magnesium phosphate cement(MPC) cementing agent for the use of cement concrete pavement patching is researched. The main factora influencing final setting time and compressive strength of MPC were explored. The results show that the final setting time of the optimizing MPC samples reaches 20 min.thP compressive strength of samples cured for 3 d and 28 d reaches respectively 43 MPa and 62 MPa,and its bond strength reaches respectively 6.2 MPa and 8.6 MPa when MPC made by horax and magnesium oxide which has a surface area of 1889cm2/g.the mol ratio of disodium hydrogen phosphate and potassium dihydrogen phosphate to be 1/5.%研究了一种用于水泥混凝土路面修补用的磷酸镁水泥(MPC)胶结剂,探讨了影响磷酸镁水泥终凝时间和抗压强度的主要因素.结果表明,以比表面积为1889 cm2/g的氧化镁粉末,与磷酸氢二钠/磷酸二氧钾(摩尔比)=1/5复合,并掺加硼砂可以制备终凝时间20min,3d和28d抗压强度分别达43、62MPa,粘结强度达6.2、8.6 MPa的磷酸镁水泥.

  7. Strength of Limestone-based Non-calcined Cement and its Properties

    Institute of Scientific and Technical Information of China (English)

    LIN Zongshou; ZHAO Qian

    2009-01-01

    A new type of cement was prepared with ground limestone powder,blastfurnace slag,steel slag and gypsum without calcination.The fraction of ground limestone powder in the cement was as high as 40 wt%-60 wt%without Portland clinker.All of its physical properties can meet the requirements of masonry cement standards.The impact of limestone content on physical properties of the cement and determined its impact on law was investigated.The steel slag can excit the aquation activity of this cement effectively,and the influence of its quantity on the strength of the materials was studied,which shows that the optimum quantity of mixing is 10%.By way of changing the different content of the lime stone by quartzy sample,the law of the compression strength and the PH value was determined,confirming that the lime stone can promote the early aquation of the slag and improve the early strength.The main hydration product of this cement is calcium aluminate hydrate, ettringite and calcium silicate hydrate,as indicated by XRD and SEM analysis.

  8. Valorisation of electric arc furnace steel slag as raw material for low energy belite cements.

    Science.gov (United States)

    Iacobescu, R I; Koumpouri, D; Pontikes, Y; Saban, R; Angelopoulos, G N

    2011-11-30

    In this paper, the valorisation of electric arc furnace steel slag (EAFS) in the production of low energy belite cements is studied. Three types of clinkers were prepared with 0 wt.% (BC), 5 wt.% (BC5) and 10 wt.% (BC10) EAFS, respectively. The design of the raw mixes was based on the compositional indices lime saturation factor (LSF), alumina ratio (AR) and silica ratio (SR). The clinkering temperature was studied for the range 1280-1400°C; firing was performed at 1380°C based on the results regarding free lime and the evolution of microstructure. In order to activate the belite, clinkers were cooled fast by blown air and concurrent crushing. The results demonstrate that the microstructure of the produced clinkers is dominated by belite and alite crystals, with tricalcium aluminate and tetracalcium-alumino-ferrite present as micro-crystalline interstitial phases. The prepared cements presented low early strength development as expected for belite-rich compositions; however the 28-day results were 47.5 MPa, 46.6 MPa and 42.8 MPa for BC, BC5 and BC10, respectively. These values are comparable with OPC CEMI 32.5 N (32.5-52.5 MPa) according to EN 197-1. A fast setting behaviour was also observed, particularly in the case of BC10, whereas soundness did not exceed 1mm.

  9. Film Thickness and Flow Properties of Resin-Based Cements at Different Temperatures

    Directory of Open Access Journals (Sweden)

    Bagheri R.

    2013-06-01

    Full Text Available Statement of Problem: For a luting agent to allow complete seating of prosthetic restorations, it must obtain an appropriate flow rate maintaining a minimum film thickness. The performance of recently introduced luting agents in this regard has not been evaluated. Purpose: To measure and compare the film thickness and flow properties of seven resin-containing luting cements at different temperatures (37°C, 25°C and10°C. Material and Methods: Specimens were prepared from five resin luting cements; seT (SDI, Panavia F (Kuraray, Varioloink II (Ivoclar, Maxcem (Kerr, Nexus2 (Kerr and two resin-modified glass-ionomer luting cements (RM-GICs; GC Fuji Plus (GC Corporation, and RelyX Luting 2 (3 M/ESPE. The film thickness and flow rate of each cement (n=15 was determined using the test described in ISO at three different temperatures. Results: There was a linear correlation between film thickness and flow rate for most of the materials. Cooling increased fluidity of almost all materials while the effect of temperature on film thickness was material dependent. At 37°C, all products revealed a film thickness of less than 25µm except for GC Fuji Plus. At 25°C, all cements pro-duced a film thickness of less than 27 µm except for seT. At 10°C, apart from seT and Rely X Luting 2, the remaining cements showed a film thickness smaller than 20 µm.Conclusion: Cooling increased fluidity of almost all materials, however. the film thickness did not exceed 35 µm in either condition, in spite of the lowest film thickness being demonstrated at the lowest temperature.

  10. Assessment of radiological hazards of naturally occurring radioactive materials in cement industry.

    Science.gov (United States)

    Aslam, Muhammad; Gul, Rahmat; Ara, Tauseef; Hussain, Manzur

    2012-09-01

    A study on the radiological hazard in Portland cement due to the presence of naturally occurring radioactive materials is being carried out. The Portland cement manufactured in the Islamabad/Rawalpindi region of Pakistan, intermediate products (clinker) and the various raw materials which compose the product have been analysed for (226)Ra, (232)Th and (40)K using a gamma spectrometry system with a N-type high-purity germanium detector of 80 % relative efficiency. From the measured gamma ray spectra, specific activities were determined. The mean values of the total specific activity of (226)Ra, (232)Th and (40)K are 34.2±11.9, 29.1±3.6 and 295.1±66.9 Bq kg(-1), respectively in Portland cement, 28.4±8.7, 11.3±1.7 and 63.1±17.3 Bq kg(-1), respectively in lime stone, 8.2±1.9, 16.2±3.9 and 187.7±53.2 Bq kg(-1), respectively in gypsum, 34.7±13.1, 41.2±6.7 and 187.6±17.2 Bq kg(-1), respectively in clay, 41.1±11.8, 39.3±6.9 and 195.1±29.2 Bq kg(-1), respectively in latrite and 51.1±18.2, 23.2±1.2 and 258.4±15.3 Bq kg(-1), respectively in clinker. The radium equivalent activities (Ra(eq)), external hazard index (H(ex)), internal hazard index (H(in)), absorbed dose rate in air (D) and annual effective dose rate (E(eff)) were also determined. The measured activity concentrations for these radio nuclides and radiological indices were compared with the reported national and international data. All these measured values are comparable with the worldwide data reported in UNSCEAR publications.

  11. Temperature prediction and analysis based on BP and Elman neural network for cement rotary kiln

    Science.gov (United States)

    Yang, Baosheng; Ma, Xiushui

    2011-05-01

    In order to reduce energy consumption and improve the stability of cement burning system production, it is necessary to conduct in-depth analysis of the cement burning system, control the operation state and law of the system. In view of the rotary kiln consumes most of the fuel, we establish the simulation model of the cement kiln used to find effective control methods. It is difficult to construct mathematical model for the rotary cement kiln as the complex parameters, so we expressed directly using neural network method to establish the simulation model for the kiln. Choosing reasonable state and control variables and collecting actual operation data to train neural network weights. We first in-depth analyze mechanism and working parameters correlation to determine factors of the yield and quality as the model input variables; then constructed cement kiln model based on BP and Elman network, both achieved good fitting results. Elman network model has a faster convergence speed, high precision and good generalization ability. So the Elman network based model can be used as simulation model of the cement rotary kiln for exploring new control method.

  12. Environmental assessment of sewage sludge as secondary raw material in cement production--a case study in China.

    Science.gov (United States)

    Hong, Jinglan; Li, Xiangzhi

    2011-06-01

    A life cycle assessment was carried out to estimate the environmental impact of sewage sludge as secondary raw material in cement production. To confirm and add credibility to the study, uncertainty analysis was conducted. Results showed the impact generated from respiratory inorganics, terrestrial ecotoxicity, global warming, and non-renewable energy categories had an important contribution to overall environmental impact, due to energy, clinker, and limestone production stages. Also, uncertainty analysis results showed the technology of sewage sludge as secondary raw material in cement production had little or no effect on changing the overall environmental potential impact generated from general cement production. Accordingly, using the technology of sewage sludge as secondary raw material in cement production is a good choice for reducing the pressure on the environment from dramatically increased sludge disposal. In addition, increasing electricity recovery rate, choosing natural gas fired electricity generation technology, and optimizing the raw material consumption in clinker production are highly recommended to reduce the adverse effects on the environment.

  13. Optimization of a novel two-solution poly(methyl methacrylate) bone cement: Effect of composition on material properties and polymerization kinetics

    Science.gov (United States)

    Hasenwinkel, Julie Miller

    strongly influence the reaction rates, but had little effect on the propagation and termination rate constants. These kinetic rates yield different microstructural properties within the materials, such as set molecular weight and residual monomer content, which can be related to the mechanical properties. These relationships can be used to refine the initiation chemistry and optimize the cement performance. Based on this research, an equimolar BPO:DMPT ratio and DMPT concentrations of 1.4 ml/100 ml MMA or less are recommended for the initiation chemistry of this novel two-solution bone cement.

  14. POZZOLAN AND CEMENTS WITH POZZOLAN

    OpenAIRE

    Hasan KAPLAN; Hanifi BİNİCİ

    1995-01-01

    Cement, one of the basic material of construction engineering, has an important place in view of strength and cost of structures. Cement consumption is increasing parallel to development of building construction sector. For cement producers, minimal cost is desired by using new and economical material sources. On the other hand, the controllers and contractors need cheaper, safer and higher strength materials. From this respect cement industry tends to use cement with pozzolan. In Türkiye, ce...

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

    Directory of Open Access Journals (Sweden)

    Stephen O. Ekolu

    2012-01-01

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

  16. PART II. HYDRATED CEMENTS

    Directory of Open Access Journals (Sweden)

    Milan Drabik

    2014-09-01

    Full Text Available Essential focus of the study has been to acquire thermoanalytical events, incl. enthalpies of decompositions - ΔH, of technological materials based on two types of Portland cements. The values of thermoanalytical events and also ΔH of probes of technological compositions, if related with the data of a choice of minerals of calcium-silicate-sulfate-aluminate hydrates, served as a valued input for the assessment of phases present and phase changes due to the topical hydraulic processes. The results indicate mainly the effects of "standard humidity" or "wet storage" of the entire hydration/hydraulic treatment, but also the presence of cement residues alongside calcium-silicate-sulfate-aluminate hydrates (during the tested period of treatment. "A diluting" effect of unhydrated cement residues upon the values of decomposition enthalpies in the studied multiphase system is postulated and discussed

  17. Push-out bond strength of MTA HP, a new high-plasticity calcium silicate-based cement.

    Science.gov (United States)

    Silva, Emmanuel Jnl; Carvalho, Nancy Kudsi; Zanon, Mayara; Senna, Plínio Mendes; DE-Deus, Gustavo; Zuolo, Mário Luis; Zaia, Alexandre Augusto

    2016-06-14

    This study was designed to investigate the resistance to dislodgment provided by MTA HP, a new high-plasticity calcium silicate-based cement. Biodentine and White MTA Angelus were used as reference materials for comparison. Three discs 1 ± 0.1 mm thick were obtained from the middle third of the roots of 5 maxillary canines. Three 0.8-mm-wide holes were drilled on the axial surface of each root disc. Standardized irrigation was performed. Then the holes were dried with paper points and filled with one of the three tested cements. The filled dental slices were immersed in a phosphate-buffered saline (PBS) solution (pH 7.2) for 7 days before the push-out assessment. The Kruskal-Wallis test was applied to assess the effect of each endodontic cement on the push-out bond strength. Mann-Whitney with Bonferroni correction was used to isolate the differences. The alpha-type error was set at 0.05. All specimens had measurable push-out values and no premature failure occurred. There were significant differences among the materials (p MTA HP had significantly higher bond strength than White MTA (p MTA HP showed better push-out bond strength than its predecessor, White MTA; however, Biodentine had higher dislodgment resistance than both MTA formulations.

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

    Directory of Open Access Journals (Sweden)

    Ortega, J. M.

    2014-03-01

    Full Text Available Special foundations, most prominently micropiles and soil anchors, are frequently used in construction today. In Spain, the grout for these special technical applications is generally prepared with portland cement, although the codes and standards in place stipulate only the minimum compressive strength required, with no mention of cement type. Those texts also establish a range of acceptable water:cement ratios. In the present study, durability and compressive strength in cement grout prepared with blast furnace slag cement at different w/c ratios are characterised and compared to the findings for a reference portland cement grout. The results show that slag grout exhibits greater durability than the portland cement material and complies with the compressive strength requirements laid down in the respective codes.Actualmente es muy frecuente el empleo de cimentaciones especiales, entre las que destacan los micropilotes y los anclajes. En España, las lechadas de cemento para estos trabajos geotécnicos especiales se preparan habitualmente con cemento Portland, aunque las diferentes normativas al respecto no restringen el tipo de cemento a emplear, siempre que se alcance una determinada resistencia a compresión. Respecto a la dosificación de las lechadas, la normativa permite emplear diferentes relaciones agua/cemento dentro de un determinado rango. En vista de ello, en este trabajo se han caracterizado las propiedades de durabilidad y resistencia a compresión de lechadas de cemento preparadas con un cemento con escoria de alto horno y con diferentes relaciones a/c, tomando como referencia de comportamiento lechadas de cemento Portland. El uso de un cemento con escoria conlleva una mejora en la durabilidad de las lechadas, cumpliendo los requisitos de resistencia a compresión establecidos por la normativa.

  19. Control of in vivo mineral bone cement degradation.

    Science.gov (United States)

    Kanter, Britta; Geffers, Martha; Ignatius, Anita; Gbureck, Uwe

    2014-07-01

    The current study aimed to prevent the formation of hydroxyapatite reprecipitates in brushite-forming biocements by minimizing the availability of free Ca(2+) ions in the cement matrix. This was achieved by both maximizing the degree of cement setting to avoid unreacted, calcium-rich cement raw materials which can deliver Ca(2+) directly to the cement matrix after dissolution, and by a reduction in porosity to reduce Ca(2+) diffusion into the set cement matrix. In addition, a biocement based on the formation of the magnesium phosphate mineral struvite (MgNH4PO4·6H2O) was tested, which should prevent the formation of low-solubility hydroxyapatite reprecipitates due to the high magnesium content. Different porosity levels were fabricated by altering the powder-to-liquid ratio at which the cements were mixed and the materials were implanted into mechanically unloaded femoral defects in sheep for up to 10 months. While the higher-porosity brushite cement quantitatively transformed into crystalline octacalcium phosphate after 10 months, slowing down cement resorption, a lower-porosity brushite cement modification was found to be chemically stable with the absence of reprecipitate formation and minor cement resorption from the implant surface. In contrast, struvite-forming cements were much more degradable due to the absence of mineral reprecipitates and a nearly quantitative cement degradation was found after 10 months of implantation.

  20. Lime mud from cellulose industry as raw material in cement mortars

    Directory of Open Access Journals (Sweden)

    Modolo, R. C.E.

    2014-12-01

    Full Text Available This study reports the use of lime mud (LM in cement-based-mortars. Lime mud is a waste generated in the production of cellulose by the kraft mill process. It is mainly composed of CaCO3, a small amount of magnesium carbonate and other trace minerals. Mortars were prepared by adding different amounts of LM (10, 20 and 30% by weight of cement in dry weight. The mortar compositions were evaluated through rheology and flow table measurements, assuring that all the samples exhibited adequate conditions for testing in both equipments. The hardened state properties were also evaluated through mechanical strengths at 7, 28 and 90 days of curing. Following a waste management solution perspective, this work intend to provide a general evaluation of LM application in cement based mortars, looking at both fresh and hardened properties in order to guarantee that the final application requirements are not hindered.Este estudio revela el uso de lodo de carbonato (LM en morteros de cemento. El LM es un residuo compuesto principalmente por CaCO3 generado en la producción de pasta de papel por el método Kraft. Los morteros se prepararon a partir de la adición de diferentes niveles de LM (10, 20 y 30% en peso de cemento en peso seco. Las composiciones de los morteros fueron caracterizadas através de mediciones de reología de mesa y de flujo, asegurando que las muestras exhibían condiciones adecuadas para su caracterización en ambos equipamientos. Las propiedades en estado endurecido también se evaluaron através de resistencias mecánicas a los 7, 28 y 90 días de cura. Con objeto de gestión de residuos, este trabajo tiene la intención de proporcionar una visión general de la aplicación de LM en los morteros, haciendo hincapié en las propiedades con el fin de garantizar que los requisitos para su aplicación final no se vean obstaculizados.

  1. Use of precalciners to remove alkali from raw materials in the cement industry. Final report, July 1978-July 1980

    Energy Technology Data Exchange (ETDEWEB)

    Gartner, E.M.

    1980-07-01

    The objective of this work was to develop an efficient means of removing alkali metal compounds (alkalies) from high-alkali aluminosilicate raw materials of the type commonly used as part of cement raw mixes in order to increase the energy efficiency of cement manufacture. The intention of this project was to determine whether the high-alkali raw materials could be pyroprocessed separately to remove the alkalies before they entered the rotary kiln, where they would be mixed with the other raw feed components. If this could be achieved, considerable savings could be made in the energy required to remove alkalies, compared to conventional methods in which the cement raw mix must be treated as a whole. Two different methods of alkali removal were examined, namely, vaporization of alkalies at relatively low temperatures; and alkali-rich melt separation at relativey high temperatures. The results showed that the removal of alkalies by pyroprocessing of high-alkali raw feed components separate from the other cement raw mix components is not likely to be a practical alternative to the best available conventional precalciner technology. (LCL)

  2. [Allergy of calcium phosphate cement material following skull reconstruction: a case report].

    Science.gov (United States)

    Mizowaki, Takashi; Miyake, Shigeru; Yoshimoto, Yuji; Matsuura, Yoshitaka; Akiyama, Sou

    2013-04-01

    The paste form of calcium phosphate cement is often used in skull reconstruction because of the biocompatibility and early handling of these cements. Although it had rarely been shown to produce a foreign body reaction, we encountered a patient who experienced an allergic reaction to calcium phosphate cements(Biopex®. A patch test was performed and a positive reaction to magnesium phosphate was obtained. Biopex® contains magnesium phosphate, so we diagnosed this case as allergic reaction. Pathological analysis revealed infiltration of plasmacytes in the bone flap around the calcium phosphate cement. The postoperative course was uneventful 3 years after surgery. Allergy to calcium phosphate cements is rare, but must be considered in differential diagnosis of its side effects.

  3. Impact of zeolite-based nanomodified additive on the structure and strength of the cement stone

    Science.gov (United States)

    Egorova, A. D.; Filippova, K. E.

    2015-01-01

    Portland cement is the main binder in the building materials industry; its properties strongly influence properties of mortars and concretes. Some regions experience difficulties with delivery and storage of Portland cement, raising the need to develop an effective additive from the available raw materials. Such materials for the Republic of Sakha (Yakutia) are zeolite-containing rocks. Studies have shown that introducing of dibutylphthalate to the composition of modified additive during mechanochemical activation leads to achievement of up to 11% of total amount particles with the size of 3-30 nm. After introducing 0.5% of the obtained additives, the compressive strength of cement-sand slurry samples increases up to 28%. Positive effect of additives introduction is also observed at high flow rate of water (W / C = 0.7). Gaining strength reaches 23%, allowing the efficient use of additive for movable mixtures with enhanced strength properties. In general, the proposed supplement allows reducing the water flow in the solution without decreasing its mobility, and increasing strength properties, which makes it possible to obtain a whole class of solutions of modified cement binder. The market value of the developed additives is 18 rubles per 1 kg, making sound competition in the market of modifying additives.

  4. Sustainable development of the cement industry and blended cements to meet ecological challenges.

    Science.gov (United States)

    Sobolev, Konstantin

    2003-05-05

    The world production of cement has greatly increased in the past 10 years. This trend is the most significant factor affecting technological development and the updating of manufacturing facilities in the cement industry. Existing technology for the production of cement clinker is ecologically damaging; it consumes much energy and natural resources and also emits pollutants. A new approach to the production of blended or high-volume mineral additive (HVMA) cement helps to improve its ecological compatibility. HVMA cement technology is based on the intergrinding of portland cement clinker, gypsum, mineral additives, and a special complex admixture. This new method increases the compressive strength of ordinary cement, improves durability of the cement-based materials, and--at the same time--uses inexpensive natural mineral additives or industrial by-products. This improvement leads to a reduction of energy consumption per unit of the cement produced. Higher strength, better durability, reduction of pollution at the clinker production stage, and decrease of landfill area occupied by industrial by-products, all provide ecological advantages for HVMA cement.

  5. Sustainable Development of the Cement Industry and Blended Cements to Meet Ecological Challenges

    Directory of Open Access Journals (Sweden)

    Konstantin Sobolev

    2003-01-01

    Full Text Available The world production of cement has greatly increased in the past 10 years. This trend is the most significant factor affecting technological development and the updating of manufacturing facilities in the cement industry. Existing technology for the production of cement clinker is ecologically damaging; it consumes much energy and natural resources and also emits pollutants. A new approach to the production of blended or high-volume mineral additive (HVMA cement helps to improve its ecological compatibility. HVMA cement technology is based on the intergrinding of portland cement clinker, gypsum, mineral additives, and a special complex admixture. This new method increases the compressive strength of ordinary cement, improves durability of the cement-based materials, and - at the same time - uses inexpensive natural mineral additives or industrial by-products. This improvement leads to a reduction of energy consumption per unit of the cement produced. Higher strength, better durability, reduction of pollution at the clinker production stage, and decrease of landfill area occupied by industrial by-products, all provide ecological advantages for HVMA cement.

  6. Comparison of in vitro cytotoxicity and genotoxicity of MMA-based polymeric materials and various metallic materials

    OpenAIRE

    İZ, Sultan GÜLÇE; GÜRHAN, Saime İsmet DELİLOĞLU; ŞEN, Bilge Hakan

    2010-01-01

    To determine the in vitro cytotoxicity and genotoxicity of some polymeric and metallic implant materials used as base materials in dentistry, based on ISO (International Organization for Standardization) and OECD (Organization for Economic Co-Operation and Development) test protocols. Materials and methods: Three different acrylate-based polymeric materials were tested for their in vitro cytotoxicity and genotoxicity (polymethylmethacrylate microspheres [PMMA], a solid cement prepared by mi...

  7. Electrical Response of Cement-Based Piezoelectric Ceramic Composites under Mechanical Loadings

    Directory of Open Access Journals (Sweden)

    Biqin Dong

    2011-01-01

    Full Text Available Electrical responses of cement-based piezoelectric ceramic composites under mechanical loadings are studied. A simple high order model is presented to explain the nonlinear phenomena, which is found in the electrical response of the composites under large mechanical loadings. For general situation, this nonlinear piezoelectric effect is quite small, and the composite is suitable for dynamic mechanical sensor as holding high static stability. The experimental results are consistent with the relationship quite well. The study shows that cement-based piezoelectric composite is suitable for potential application as dynamic mechanical sensor with excellent dynamic response and high static stability.

  8. Microstructure of TiC-Based Coatings on Cemented Carbide Derived by Sol-Gel Routes

    Science.gov (United States)

    Yang, Mei; Guo, Zhixing; Qi, Kaifeng; Huang, Kun; Deng, Jianxiong; Liu, Jia

    2016-12-01

    TiC-based coating is prepared by depositing TiO2 sol on cemented carbide compact and liquid phase sintering. TiC forms due to carbothermal reduction reaction of TiO2 and then reacts with WC and transforms to TiC-based solid solution. Ti content changes the WC growth mechanism and results in the multi-stepped morphology. When sintered cemented carbide is used as substrate, WC keeps the equilibrium truncated triangle prism morphology due to the relatively weak diffusion among Ti, WC, and Co.

  9. Microstructure of TiC-Based Coatings on Cemented Carbide Derived by Sol-Gel Routes

    Science.gov (United States)

    Yang, Mei; Guo, Zhixing; Qi, Kaifeng; Huang, Kun; Deng, Jianxiong; Liu, Jia

    2017-02-01

    TiC-based coating is prepared by depositing TiO2 sol on cemented carbide compact and liquid phase sintering. TiC forms due to carbothermal reduction reaction of TiO2 and then reacts with WC and transforms to TiC-based solid solution. Ti content changes the WC growth mechanism and results in the multi-stepped morphology. When sintered cemented carbide is used as substrate, WC keeps the equilibrium truncated triangle prism morphology due to the relatively weak diffusion among Ti, WC, and Co.

  10. Polymeric-Calcium Phosphate Cement Composites-Material Properties: In Vitro and In Vivo Investigations

    Science.gov (United States)

    Khashaba, Rania M.; Moussa, Mervet M.; Mettenburg, Donald J.; Rueggeberg, Frederick A.; Chutkan, Norman B.; Borke, James L.

    2010-01-01

    New polymeric calcium phosphate cement composites (CPCs) were developed. Cement powder consisting of 60 wt% tetracalcium phosphate, 30 wt% dicalcium phosphate dihydrate, and 10 wt% tricalcium phosphate was combined with either 35% w/w poly methyl vinyl ether maleic acid or polyacrylic acid to obtain CPC-1 and CPC-2. The setting time and compressive and diametral tensile strength of the CPCs were evaluated and compared with that of a commercial hydroxyapatite cement. In vitro cytotoxicity and in vivo biocompatibility of the two CPCs and hydroxyapatite cement were assessed. The setting time of the cements was 5–15 min. CPC-1 and CPC-2 showed significantly higher compressive and diametral strength values compared to hydroxyapatite cement. CPC-1 and CPC-2 were equivalent to Teflon controls after 1 week. CPC-1, CPC-2, and hydroxyapatite cement elicited a moderate to intense inflammatory reaction at 7 days which decreased over time. CPC-1 and CPC-2 show promise for orthopedic applications. PMID:20811498

  11. Polymeric-Calcium Phosphate Cement Composites-Material Properties: In Vitro and In Vivo Investigations

    Directory of Open Access Journals (Sweden)

    Rania M. Khashaba

    2010-01-01

    Full Text Available New polymeric calcium phosphate cement composites (CPCs were developed. Cement powder consisting of 60 wt% tetracalcium phosphate, 30 wt% dicalcium phosphate dihydrate, and 10 wt% tricalcium phosphate was combined with either 35% w/w poly methyl vinyl ether maleic acid or polyacrylic acid to obtain CPC-1 and CPC-2. The setting time and compressive and diametral tensile strength of the CPCs were evaluated and compared with that of a commercial hydroxyapatite cement. In vitro cytotoxicity and in vivo biocompatibility of the two CPCs and hydroxyapatite cement were assessed. The setting time of the cements was 5–15 min. CPC-1 and CPC-2 showed significantly higher compressive and diametral strength values compared to hydroxyapatite cement. CPC-1 and CPC-2 were equivalent to Teflon controls after 1 week. CPC-1, CPC-2, and hydroxyapatite cement elicited a moderate to intense inflammatory reaction at 7 days which decreased over time. CPC-1 and CPC-2 show promise for orthopedic applications.

  12. CALIBRATIONS BASED ON NEAR INFRARED SPECTROSCOPIC DATA TO ESTIMATE WOOD-CEMENT PANEL PROPERTIES

    Directory of Open Access Journals (Sweden)

    Paulo Ricardo Gherardi Hein

    2009-11-01

    Full Text Available Some scientific contributions have used near infrared (NIR spectroscopy as a rapid and reliable tool for characterizing engineered wood products. However, to our knowledge, there are no published papers that used this technique in order to evaluate wood-cement panels. The main objective of this paper was to evaluate the ability of NIR spectroscopy to estimate physical and mechanical properties in wood-cement panels. The wood-cement panels were produced using Eucalyptus grandis x E. urophylla, Pinus taeda, and Toona ciliata woods with Portland cement under different manufacturing conditions. Wood-cement panels were characterized by traditional methods, and Partial Least Squares regressions were used to build calibrations. Our cross-validated models for MOR, IB, and TS24h of the panels yielded good coefficients of determination (0.80, 0.82, and 0.91, respectively. Based on the significant absorption bands and regression coefficients of the PLS models, our results indicate that cellulose and aromatic groups in lignin are components that play an important role in the calibrations.

  13. Marginal gap, cement thickness, and microleakage of 2 zirconia crown systems luted with glass ionomer and MDP-based cements.

    Science.gov (United States)

    Sener, Isil; Turker, Begum; Valandro, Luiz Felipe; Ozcan, Mutlu

    2014-01-01

    This in vitro study evaluated the marginal gap, cement thickness, and microleakage of glass-ionomer cement (GIC) and phosphate monomer-containing resin cement (MDP-RC) under 2 zirconia crown systems (Cercon and DC-Zirkon). Forty human premolars were prepared for all-ceramic zirconia crowns with a 1 mm circumferential finish line and a 1.5 mm occlusal reduction. The crowns (n = 10 per group) from each zirconia system were randomly divided into 2 groups and cemented either with GIC (Vivaglass CEM) or MDP-RC (Panavia F 2.0) cement. The cemented crowns were thermocycled 5000 times (5°-55°C). The crowns were immersed in 0.5% basic fuchsine dye solution for 24 hours and sectioned buccolingually and mesiodistally. Specimens were examined under optical microscope (100X). Data were analyzed using Student t-test and chi-square tests (α = 0.05). Mean marginal gap values for Cercon (85 ± 11.4 μm) were significantly higher than for DC-Zircon (75.3 ± 13.2 μm) (P = 0.018). The mean cement thickness values of GIC (81.7 ± 13.9 μm) and MDP-RC (78.5 ± 12.5 μm) were not significantly different (P = 0.447). Microleakage scores did not demonstrate significant difference between GIC (P = 0.385) and MDP-RC (P = 0.631) under Cercon or DC-Zircon. Considering the cement thickness values and microleakage scores obtained, both zirconia crown systems could be cemented in combination with either GIC or MDP-RC.

  14. The Effect of abutment wall modification, filling material & copying design on retention of cement retained implant supported crown

    Directory of Open Access Journals (Sweden)

    Shima Aalaei

    2016-12-01

    Full Text Available Background and aim: Factors which can effect of tooth supported crowns are well known. On the other side, low information are existed about retention of implant supported crowns. The aim of the present study was to evaluate the effect of abutment wall modification, filling material & copying design on retention of cement retained implant supported crown. Materials and methods: In this study, 4 straight abutments were attached to their implant analogues and were embedded in the acrylic resin block. Abutments were modified to one, two, three and four walls. Then, two type copying were made: conventional and with metal extension in two screw access cavity. Access cavities were filled incompletely by three methods: copying with extension spread into the access cavity without material and conventional copying with polytetrafluoroethylene (PTFE or composite. Then cemented with temporary agent (TempBond. Required tensile force for separation of copying was measured by universal testing machine. Data were analyzed using ANOVA as statistical test. Results: About findings of this research, no significant difference were detected among two methods of filling of access cavity and engaging screw access channel (P>0.05. Four wall abutment shown significantly higher retention than the others (P<0.05 and three other abutments have no significant difference in retention. Conclusion: The type of filling material of access cavity (PTFE and composite and engaging of the copying design have no significant effects on the cemented retained of implant supported restoration but existence of all four septums increase the veneer retention significantly.

  15. 7th NCB international seminar on cement and building materials. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    Topics covered include: mining and mine environment (including CO{sub 2} mitigation in cement concrete industries), and project engineering and management (in volume 1); productivity enhancement and process optimisation (upgrading/cost reduction, grinding/refractories, process optimisation and control, and maintenance) (in volume 2); plant environment and pollution control (including global climate change) performance of concrete, and Portland and blended cements (in volume 3); special cements and binders, total quality management and energy management (in volume 4); and supplementary papers in volume 5.

  16. Effect of light-curing method and indirect veneering materials on the Knoop hardness of a resin cement

    Directory of Open Access Journals (Sweden)

    Nelson Tetsu Iriyama

    2009-06-01

    Full Text Available This study evaluated the Knoop hardness of a dual-cured resin cement (Rely-X ARC activated solely by chemical reaction (control group or by chemical / physical mode, light-cured through a 1.5 mm thick ceramic (HeraCeram or composite (Artglass disc. Light curing was carried out using conventional halogen light (XL2500 for 40 s (QTH; light emitting diodes (Ultrablue Is for 40 s (LED; and Xenon plasma arc (Apollo 95E for 3 s (PAC. Bovine incisors had their buccal face flattened and hybridized. On this surface a rubber mold (5 mm in diameter and 1 mm in height was bulk filled with the resin cement. A polyester strip was seated for direct light curing or through the discs of veneering materials. After dry storage in the dark (24 h 37°C, the samples (n = 5 were sectioned for hardness (KHN measurements, taken in a microhardness tester (50 gF load 15 s. The data were statistically analyzed by ANOVA and Tukey's test (α = 0.05. The cement presented higher Knoop hardness values with Artglass for QTH and LED, compared to HeraCeram. The control group and the PAC/Artglass group showed lower hardness values compared to the groups light-cured with QTH and LED. PAC/HeraCeram resulted in the worst combination for cement hardness values.

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

    Directory of Open Access Journals (Sweden)

    Zarabian M.

    2005-07-01

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

  18. 水泥基材料极早期水化机理及微观结构分析%Early Hydration Mechanism and Microstructural Analysis of Cement-based Materials

    Institute of Scientific and Technical Information of China (English)

    张文强; 李海玉; 陈帅

    2014-01-01

    The issue about the study of ion concentration of pore solution in hydration of cement will try to explain the very early hydration process and its mechanism of hydration.In addition,the issue uses the method of corrupting fly ash by alkaline solution to simulate the impact of pore solution alkalinity reacting hydration and hydration products. The results show that the basic trend of the ion concentration is consistent,which mixed 0,10%,20% of ash respec-tively.Its change is different to the ion concentration of pore solution,because in the beginning stages of hydration,it is mainly controlled by the alkaline soluble substances.Additionally to AFM observation,the change of microstructure of fly ash is closely related to the concentration of alkali ions.%测试了水泥浆体中孔溶液离子浓度在水化极早期的演变规律;运用原子力显微镜(AFM),采用碱性模拟溶液腐蚀粉煤灰的方法来研究了水化过程中孔溶液碱度对粉煤灰化学反应活性以及水化反应和水化产物生成的影响。研究结果表明:粉煤灰掺量分别为0、10%、20%的三种水泥水化孔溶液各离子浓度随水化时间的推移,其变化趋势基本是相同的。水化最开始的阶段孔溶液离子浓度主要是由碱性物溶解控制,其变化呈现差异性。AFM观察结果表明,碱性溶液可以侵蚀粉煤灰颗粒表面,改变其微观结构,改变的程度与侵蚀溶液碱离子浓度密切相关。经侵蚀的粉煤灰颗粒表面有纤维状水化产物形成。

  19. LDEF materials data bases

    Science.gov (United States)

    Funk, Joan G.; Strickland, John W.; Davis, John M.

    1993-01-01

    The Long Duration Exposure Facility (LDEF) and the accompanying experiments were composed of and contained a wide variety of materials representing the largest collection of materials flown in low Earth orbit (LEO) and retrieved for ground based analysis to date. The results and implications of the mechanical, thermal, optical, and electrical data from these materials are the foundation on which future LEO space missions will be built. The LDEF Materials Special Investigation Group (MSIG) has been charged with establishing and developing data bases to document these materials and their performance to assure not only that the data are archived for future generations but also that the data are available to the spacecraft user community in an easily accessed, user-friendly form. This paper discusses the format and content of the three data bases developed or being developed to accomplish this task. The hardware and software requirements for each of these three data bases are discussed along with current availability of the data bases. This paper also serves as a user's guide to the MAPTIS LDEF Materials Data Base.

  20. New high temperature cementing materials for geothermal wells: stability and properties. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Roy, D.M.; White, E.L.; Langton, C.A.; Grutzeck, M.W.

    1980-07-01

    Potential high-temperature cements have been formulated and evaluated in terms of their properties for geothermal well cementing. Phase formation and compatibility in two major compositional regions were investigated in the temperature region between 200 and 400/sup 0/C and pressures up to 69 MPa (10,000 psi). These were followed by an evaluation of properties of the cements formed. One area in the system Ca0-Mg0-Si0/sub 2/-H/sub 2/0 centered around the xonotlite-chrysotile join while the other area of interest centered around the anorthite composition in the system Ca0-Al/sub 2/O/sub 3/-SiO/sub 2/-H/sub 2/O. After numerous exploratory studies, the magnesia-containing mixtures were prepared by mixing a Class J cement with various sources of magnesia such as calcined chrysotile, or magnesium oxide. Calcium oxide and silica fine quartz powder were also added to adjust the compositions. The aluminous system cements were formulated from high-alumina cements which were mixed with various silica sources.

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

    Science.gov (United States)

    Apih, T.; Lebar, A.; Pawlig, O.; Trettin, R.

    2001-06-01

    Proton nuclear magnetic relaxation is a well-established technique for continuous and non destructive monitoring of hydration of conventional Portland building cements. Here, we demonstrate the feasibility of nuclear magnetic resonance (NMR) monitoring of the setting reaction of zinc-phosphate acid-base dental cements, which harden in minutes as compared to days, as in the case of Portland cements. We compare the setting of cement powder (mainly, zinc oxide) prepared with clinically used aluminum-modified orthophosphoric acid solution with the setting of a model system where cement powder is mixed with pure orthophosphoric acid solution. In contrast to previously published NMR studies of setting Portland cements, where a decrease of spin-lattice relaxation time is attributed to enhanced relaxation at the growing internal surface, spin-lattice relaxation time T1 increases during the set of clinically used zinc-phosphate cement. Comparison of these results with a detailed study of diffusion, viscosity, and magnetic-field dispersion of T1 in pure and aluminum-modified orthophosphoric acid demonstrates that the increase of T1 in the setting cement is connected with the increase of molecular mobility in the residual phosphoric acid solution. Although not taken into account so far, such effects may also significantly influence the relaxation times in setting Portland cements, particularly when admixtures with an effect on water viscosity are used.

  2. Piezoresistivity of Carbon Fiber Graphite Cement-based Composites with CCCW

    Institute of Scientific and Technical Information of China (English)

    FAN Xiaoming; FANG Dong; SUN Mingqing; LI Zhuoqiu

    2011-01-01

    The electrical conductivity and piezoresistivity of carbon fiber graphite cement-matrix composites(CFGCC) with carbon fiber content(l% by the weight of cement), graphite powder contents (0%-50% by the weight of cement) and CCCW(cementitious capillary crystalline waterproofing materials, 4% by the weight of cement) were studied. The experimental results showed that the relationship between the resistivity of CFGCC and the concentration of graphite powders had typical features of percolation phenomena. The percolation threshold was about 20%. A clear piezoresistive effect was observed in CFGCC with 1 wt% of carbon fibers, 20wt% or 30wt% of graphite powders under uniaxial compressive tests, indicating that this type of smart composites was a promising candidate for strain sensing. The measured gage factor (defined as the fractional change in resistance per unit strain) of CFGCC with graphite content of 20wt% and 30wt% were 37 and 22, respectively. With the addition of CCCW, the mechanical properties of CFGCC were improved, which benefited CFGCC piezoresistivity of stability.

  3. Mechanical Properties and Biocompatibility of a Biomaterial Based on Deproteinized Hydroxyapatite and Endodentine Cement

    Directory of Open Access Journals (Sweden)

    Rupeks Lauris

    2016-05-01

    Full Text Available Hydroxyapatite is used for bone reconstruction, in order to improve its mechanical properties different substances can be added. In our study new biomaterial is created from deproteinised hydroxyaptite and endodentic cement, its mechanical properties were tested. Material was implanted subcutaneous in rats, then histological and biocompatability tests were performed. Results indicate that stuff has good mechanical properties, short setting time and gradual resorption creating porosity and ability to integrate in bone.

  4. Microleakage of conventional, resin-modified, and nano-ionomer glass ionomer cement as primary teeth filling material

    Directory of Open Access Journals (Sweden)

    Dita Madyarani

    2014-12-01

    Full Text Available Background: Glass ionomer cements are one of many dental materials that widely used in pediatric dentistry due to their advantage of fluoride release and chemical bond to tooth structure. Adherence of the filling material to the cavity walls is one of the most important characteristic that need to be examined its effect on microleakage. Purpose: This study was conducted to examine the microleakage of nano-ionomer glass ionomer cement compared with the conventional and resin-modified glass ionomer cements. Methods: Standard class V cavities sized 3 mm x 2 mm x 2 mm were made on a total of 21 extracted maxillary primary canine teeth and restored with the conventional, resin-modified, dan nano-ionomer glass ionomer cements. All the teeth were immersed in a 2% methylene blue dye for 4 hours. The depth of dye penetration was assessed using digital microscope after sectioning the teeth labio-palatally. The results were statistically analyzed using Kruskal-Wallis test. Results: All type of glass ionomer material showed microleakage. Conventional glass ionomer cement demonstrated the least microleakage with mean score 1.29. the resin-modified glass ionomer cements (mean score 1.57 and nano-ionomer glass ionomer cement (mean score 2.57. Conclusion: The conventional glassionomer, resin modified glassionomer, and nano-ionomer glassionomer showed micro leakage as filling material in primary teeth cavity. The micro leakage among three types was not significant difference. All three material were comparable in performance and can be used for filling material but still needs a coating material to fill the microleakage.Latar belakang: Semen ionomer kaca adalah salah satu dari banyak bahan gigi yang banyak digunakan dalam praktek kedokteran gigi anak karena bahan tersebut merilis fluoride dan berikatan kimia dengan struktur gigi. Perlekatan bahan tumpatan pada dinding kavitas adalah salah satu karakteristik paling penting yang perlu diteliti efeknya terhadap

  5. Bioactive materials improve some physical properties of a MTA-like cement.

    Science.gov (United States)

    Flores-Ledesma, A; Barceló Santana, F; Bucio, L; Arenas-Alatorre, J A; Faraji, M; Wintergerst, A M

    2017-02-01

    One of the main disadvantages of MTA is its long setting time which could result in higher solubility and microleakage, producing a failed treatment. Studies have shown that the addition of bioactive glass may decrease the setting time. The aim of this study is to evaluate the compressive strength, setting time, solubility and radiopacity of a MTAlike experimental cement to which different percentage of wollastonite and bioactive glass are added. White MTA Angelus® was used as control; an experimental MTA-like cement (ExpC) was prepared using white Portland cement with 20wt% of Bi2O3; three wollastonite cement composites were prepared adding 10, 20 and 30wt% of wollastonite to ExpC, and three more adding the same proportions of bioactive glass. Compressive strength was tested according to ADA 30; radiopacity, setting time and solubility were tested according to ISO 6876. SEM observations of the surface were made after the solubility test. Compressive strength, setting time, solubility and radiopacity were reduced as the wollastonite increased; solubility increased with the addition of bioactive glass. The surfaces of MTA Angelus® and ExpC were smoother than Wollastonite and Bioactive glass groups. Addition of wollastonite and bioactive glass improved the physical properties of a MTA-like experimental cement, reducing the setting time with good solubility percentages, which would be an advantage in its clinical use.

  6. Shrinkage Properties of Cement Stabilized Gravel

    DEFF Research Database (Denmark)

    Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard

    2014-01-01

    Cement stabilized gravel is an attractive material in road construction because its strength prop-erties are accommodating the increasingly higher requirements to the bearing capacity of a base course. However, reflection cracking of cement stabilized gravel is a major concern. In this pa......-per the shrinkage properties of cement stabilized gravel have been documented under various temperature and relative humidity conditions. Two cement contents corresponding to a 28-days compressive strength of 6.2 MPa and 12.3 MPa have been tested and compared. It is found that the coefficient of linear expansion...... for the two cement contents is 9.9 × 10-6 ⁰C-1 and 11.3 × 10-6 ⁰C-1, respectively. Furthermore, it is found that reflecting cracking can mainly be explained by temperature dependent shrinkage rather than moisture dependent shrinkage....

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

    Directory of Open Access Journals (Sweden)

    Maura Cristiane Gonçales Orçati Dorileo

    2014-01-01

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

  8. Biomonitoring Study of Heavy Metals in Blood from a Cement Factory Based Community

    Directory of Open Access Journals (Sweden)

    Bank M.S.

    2014-07-01

    Full Text Available Little is known about the effects of cement factory pollution, emissions, and kiln dust on contaminant exposure in human populations, including school environments, in close proximity to these point sources. In Ravena, New York, USA and vicinity, environmental pollution from a local cement plant is considered significant and substantial according to the United States Environmental Protection Agency’s Toxic Release Inventory, published in 2006, 2007, and 2010. We hypothesized that cement factory based communities, such as the one in Ravena, NY, may be differentially exposed to heavy metals, including mercury, via dust, soil, and air in addition to any contributions from fish consumption, dental amalgams, smoking habits, and occupational exposures, etc. Here we report measurements of several heavy metals in blood (Pb, Cd, As, Hg, Se and Al and, for comparative purposes, total mercury in hair from a local (six-mile radius population of Caucasian adults and children. We also report and synthesize local atmospheric emissions inventory information and new indoor air data (NYSERDA, 2011 from the local school which is situated directly across the street (within 750 feet from the cement factory and quarry. In addition, to our human and environmental heavy metal results we also discuss scientific outreach coordination, and public health action opportunities that will likely have wide applicability for other community and environmental health studies confronting similar pollution issues.

  9. Development and comparison of neural network based soft sensors for online estimation of cement clinker quality.

    Science.gov (United States)

    Pani, Ajaya Kumar; Vadlamudi, Vamsi Krishna; Mohanta, Hare Krishna

    2013-01-01

    The online estimation of process outputs mostly related to quality, as opposed to their belated measurement by means of hardware measuring devices and laboratory analysis, represents the most valuable feature of soft sensors. As of now there have been very few attempts for soft sensing of cement clinker quality which is mostly done by offline laboratory analysis resulting at times in low quality clinker. In the present work three different neural network based soft sensors have been developed for online estimation of cement clinker properties. Different input and output data for a rotary cement kiln were collected from a cement plant producing 10,000 tons of clinker per day. The raw data were pre-processed to remove the outliers and the resulting missing data were imputed. The processed data were then used to develop a back propagation neural network model, a radial basis network model and a regression network model to estimate the clinker quality online. A comparison of the estimation capabilities of the three models has been done by simulation of the developed models. It was observed that radial basis network model produced better estimation capabilities than the back propagation and regression network models.

  10. Acoustic emission for characterising the crack propagation in strain-hardening cement-based composites (SHCC)

    Energy Technology Data Exchange (ETDEWEB)

    Paul, S.C. [Department of Civil Engineering, Stellenbosch University (South Africa); Pirskawetz, S. [BAM Federal Institute for Materials Research and Testing (Germany); Zijl, G.P.A.G. van, E-mail: gvanzijl@sun.ac.za [Department of Civil Engineering, Stellenbosch University (South Africa); Schmidt, W. [BAM Federal Institute for Materials Research and Testing (Germany)

    2015-03-15

    This paper presents the analysis of crack propagation in strain-hardening cement-based composite (SHCC) under tensile and flexural load by using acoustic emission (AE). AE is a non-destructive technique to monitor the development of structural damage due to external forces. The main objective of this research was to characterise the cracking behaviour in SHCC in direct tensile and flexural tests by using AE. A better understanding of the development of microcracks in SHCC will lead to a better understanding of pseudo strain-hardening behaviour of SHCC and its general performance. ARAMIS optical deformation analysis was also used in direct tensile tests to observe crack propagation in SHCC materials. For the direct tensile tests, SHCC specimens were prepared with polyvinyl alcohol (PVA) fibre with three different volume percentages (1%, 1.85% and 2.5%). For the flexural test beam specimens, only a fibre dosage of 1.85% was applied. It was found that the application of AE in SHCC can be a good option to analyse the crack growth in the specimens under increasing load, the location of the cracks and most importantly the identification of matrix cracking and fibre rupture or slippage.

  11. Study on the Compressive Performance of a New Type Cemented-Filling Material Based on Industrial Waste Slag and Tailings%新型工业废渣-尾矿基胶结充填材料的抗压性能研究

    Institute of Scientific and Technical Information of China (English)

    杨明录; 刘允秋

    2016-01-01

    为缓解高炉渣、尾矿等工业废渣的大量堆存对环境的危害,降低矿山开采胶结充填成本,探讨以尾矿和高炉渣、石膏、赤泥等工业废渣为主要原材料,以固体水玻璃为激活剂,制备新型工业废渣-尾矿基胶结充填材料的试验。得出最佳配方为:浆料浓度70%、灰砂比1∶3.89,高炉渣78.70%、石灰11.11%、石膏2.78%、固体水玻璃7.41%,并对高炉矿渣在胶结充填中的胶凝机理进行了研究,对尾矿资源再利用及工业生产具有重要的指导意义。%In order to alleviate the harm of the stockpiling of blast furnace slag to environment and reduce the cost mining cemented filling,the tailings,blast furnace slag,gypsum,red mud and other indus-trial waste slag are taken as the main raw materials,the solid sodium silicate is taken as the activator to conduct the experiment of producting the new cemented-filling material.The experimental results show that the optimal formular of the new cemented-filling material including slurry concentration (70%),ce-ment sand ratio (1∶3.89),blast furnance slag (78.70%),lime (11.11%),gypsum (2.78%)and sol-id sodium silicate (7.41%),besides that,the gelation mechanism of blast furnace slag in the new cemen-ted-filling material is also analyzed in detail,the above analysis results have some the important instruction significance to the resources reutilization and industrial production.

  12. 不同养护条件下煤矸石集料-水泥基材料力学性能影响的试验研究%Experimental research on the influence of coal gangue aggregate-cement-based materials on the mechanical properties under different curing conditions

    Institute of Scientific and Technical Information of China (English)

    段晓牧; 夏军武; 曹极昌; 杨风州

    2014-01-01

    It selected spontaneous combustion(active) and non-spontaneous combustion(inactive) two kinds of coal gangues as concrete aggregates,the development trend of mechanical properties of coal gangue aggregates-cement-based materials under the standard curing and high-temperature-water curing conditions were observed,the results can provided the basis of application on the coal gangue as con-crete aggregates.Results of the trial indicated that for the coal gangue as fine aggregates-cement-based materials ,under the high-tem pera-ture-water curing,could improved the early (3,7 d) compressive strength,but it could generated the negative effect in the later period under the high temperature curing,however,the impact on the concrete flexural strength were opposite;for the coal gangue aggregates concrete,the high-temperature-water curing was beneficial to the mechanical properties of concrete,especially to the spontaneous combustion gangues concrete,because the high-temperature-water curing could stimulated the gangues activity,and hadn't generated the negative effect.%选用自燃(活性)和非自燃(非活性)煤矸石作为粗、细集料,研究标准养护和高温水养护条件下两种矸石集料-水泥基材料力学性能的发展规律,为解决煤矸石集料在水泥混凝土中的应用提供依据。试验结果表明:对于煤矸石细集料-水泥浆体而言,高温水养护条件下,有利于提高两种矸石细集料-水泥基材料早期(3、7d)的抗压强度,但对矸石细集料-水泥基材料的后期抗压强度的发展会产生高温负效应,但是对抗折强度的影响正好相反;对于煤矸石集料混凝土,高温水养护对其力学性能发的展是有利的,特别是对自燃矸石集料混凝土,高温水养护能够在一定程度上激发其火山灰活性,对其强度的发展有利,并不会产生“高温负效应”。

  13. 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.

  14. Analysis of an Orthotropic Deck Stiffened with a Cement-Based Overlay

    DEFF Research Database (Denmark)

    Walter, Rasmus; Olesen, John Forbes; Stang, Henrik;

    2007-01-01

    Over the past years, with increasing traffic volumes and higher wheel loads, fatigue damage in steel parts of typical orthotropic steel bridge decks has been experienced on heavily trafficked routes. A demand exists to find a durable system to increase the fatigue safety of orthotropic steel bridge...... decks. A solution might be to enhance the stiffness of the traditional orthotropic bridge deck by using a cement-based overlay. In this paper, an orthotropic steel bridge deck stiffened with a cement-based overlay is analyzed. The analysis is based on nonlinear fracture mechanics, and utilizes...... the finite-element method. The stiffness of the steel deck reinforced with an overlay depends highly on the composite action. The composite action is closely related to cracking of the overlay and interfacial cracking between the overlay and underlying steel plate (debonding). As an example, a real size...

  15. The contemporary cement cycle of the United States

    Science.gov (United States)

    Kapur, A.; Van Oss, H. G.; Keoleian, G.; Kesler, S.E.; Kendall, A.

    2009-01-01

    A country-level stock and flow model for cement, an important construction material, was developed based on a material flow analysis framework. Using this model, the contemporary cement cycle of the United States was constructed by analyzing production, import, and export data for different stages of the cement cycle. The United States currently supplies approximately 80% of its cement consumption through domestic production and the rest is imported. The average annual net addition of in-use new cement stock over the period 2000-2004 was approximately 83 million metric tons and amounts to 2.3 tons per capita of concrete. Nonfuel carbon dioxide emissions (42 million metric tons per year) from the calcination phase of cement manufacture account for 62% of the total 68 million tons per year of cement production residues. The end-of-life cement discards are estimated to be 33 million metric tons per year, of which between 30% and 80% is recycled. A significant portion of the infrastructure in the United States is reaching the end of its useful life and will need to be replaced or rehabilitated; this could require far more cement than might be expected from economic forecasts of demand for cement. ?? 2009 Springer Japan.

  16. Modelling of the interaction between chemical and mechanical behaviour of ion exchange resins incorporated into a cement-based matrix

    Directory of Open Access Journals (Sweden)

    Le Bescop P.

    2013-07-01

    Full Text Available In this paper, we present a predictive model, based on experimental data, to determine the macroscopic mechanical behavior of a material made up of ion exchange resins solidified into a CEM III cement paste. Some observations have shown that in some cases, a significant macroscopic expansion of this composite material may be expected, due to internal pressures generated in the resin. To build the model, we made the choice to break down the problem in two scale’s studies. The first deals with the mechanical behavior of the different heterogeneities of the composite, i.e. the resin and the cement paste. The second upscales the information from the heterogeneities to the Representative Elementary Volume (REV of the composite. The heterogeneities effects are taken into account in the REV by applying a homogenization method derived from the Eshelby theory combined with an interaction coefficient drawn from the poroelasticity theory. At the first scale, from the second thermodynamic law, a formulation is developed to estimate the resin microscopic swelling. The model response is illustrated on a simple example showing the impact of the calculated internal pressure, on the macroscopic strain.

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

    Science.gov (United States)

    Edwards, Christopher Lane

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

  18. Human tooth germ stem cell response to calcium-silicate based endodontic cements

    Directory of Open Access Journals (Sweden)

    Esra Pamukcu Guven

    2013-07-01

    Full Text Available OBJECTIVE: The aim of this study was to compare the cytotoxic effects of endodontic cements on human tooth germ stem cells (hTGSCs. MTA Fillapex, a mineral trioxide aggregate (MTA-based, salicylate resin containing root canal sealer, was compared with iRoot SP, a bioceramic sealer, and AH Plus Jet, an epoxy resin-based root canal sealer. MATERIAL AND METHODS: To evaluate cytotoxicity, all materials were packed into Teflon rings (4 mmµ3 mm and co-cultured with hTGSCs with the aid of 24-well Transwell permeable supports, which had a pore size of 0.4 µm. Coverslips were coated with MTA Fillapex, iRoot SP and AH Plus Jet and each coverslip was placed onto the bottom of one well of a six-well plate for scanning electron microscopy (SEM analysis. Before the cytotoxicity and SEM analysis, all samples were stored at 37ºC and at 95% humidity and 5% CO2 for 24 hours to set. The cellular viability was analyzed using MTS test (3-(4,5-dimethyl-thiazol-2-yl-5-(3-carboxy-methoxy-phenyl-2-(4-sulfo-phenyl-2H-tetrazolium. The cytotoxic effects and SEM visualization of the tested materials were analyzed at 24-hour, 72-hour, one-week and two-week periods. RESULTS: On the 1st day, only MTA Fillapex caused cytotoxicity compared to negative control (NC group (p0.05. After 14 days of incubation with the test materials, MTA Fillapex exhibited significantly higher cytotoxicity compared with iRoot SP, AH Plus Jet and the NC group (P<0.008. In the SEM analysis, the highest levels of cell attachment were observed for iRoot SP and the control group. After 24 hours, MTA Fillapex reduced the number of cells attached to the surface. CONCLUSIONS: Within the limitations of this study, sealers exerted different cytotoxic effects on hTGSCs. Although all materials have exerted cellular toxicity, iRoot SP and AH Plus Jet may promote better attachment to hTGSCs.

  19. Utilization of cement treated recycled concrete aggregates as base or subbase layer in Egypt

    Directory of Open Access Journals (Sweden)

    Ahmed Ebrahim Abu El-Maaty Behiry

    2013-12-01

    Full Text Available Recently, environmental protection has a great concern in Egypt where recycling of increased demolition debris has become a viable option to be incorporated into roads applications. An extensive laboratory program is conducted to study the feasibility of using recycled concrete aggregate (RCA mixed with traditional limestone aggregate (LSA which is currently being used in base or subbase applications in Egypt. Moreover, the influence of mixture variables on the mechanical properties of cement treated recycled aggregate (CTRA is investigated. Models to predict the compressive and tensile strengths based on mixture parameters are established. The results show that the adding of RCA improves the mechanical properties of the mixture where the unconfined compressive strength (UCS is taken as an important quality indicator. Variables influencing the UCS such as cement content, curing time, dry density play important roles to determine the performance of CTRA.

  20. Influence of adjuvants on the properties of underwater cast concrete on base of cement (HRS 32.5 N

    Directory of Open Access Journals (Sweden)

    Rouis Mohamed Jamel

    2014-04-01

    *The characterization tests of concrete in the hardened state including destructive and non destructive tests performed on specimens made in concrete (based on portland cement, with varying dosages and adjuvants at different times (28d and 90d.

  1. Cement Conundrum

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    China aims to streamline the crowded cement industry Policymakers are looking to build a concrete wall around the cement-making industry as they seek to solidify the fluid cement market and cut excessive production.

  2. Production of cement requiring low energy expenditure. An industrial test

    Energy Technology Data Exchange (ETDEWEB)

    Gimenez, S.; Blanco, M.T.; Palomo, A.; Puertas, F. (Instituto de Ciencias de la Construccion, Madrid (Spain))

    1991-01-01

    A new method for making cement is proposed. It is based on the use of CaF{sub 2} and CaSO{sub 4} for partial replacement of the usual raw materials in cement manufacturing. This paper shows the feasibility of the proposed method on an industrial scale. A test carried out in a Spanish cement factory (1500 t yield of the new cement) has revealed that the mehtod can not only be adapted to the current technology but also requires a much lower energy expenditure. The final product is shown to have excellent properties in comparison with OPC. (orig.).

  3. 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.

  4. Surface characterization of the cement for retention of implant supported dental prostheses: In vitro evaluation of cement roughness and surface free energy

    Energy Technology Data Exchange (ETDEWEB)

    Brajkovic, Denis [Clinic for Dentistry, Department of Maxillofacial Surgery, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34000 Kragujevac (Serbia); Antonijevic, Djordje; Milovanovic, Petar [Laboratory for Anthropology, Institute of Anatomy, School of Medicine, University of Belgrade, Dr. Subotica 4/2, 11000 Belgrade (Serbia); Kisic, Danilo [Laboratory for Atomic Physics, Institute of Nuclear Sciences “Vinca”, University of Belgrade, Belgrade (Serbia); Zelic, Ksenija; Djuric, Marija [Laboratory for Anthropology, Institute of Anatomy, School of Medicine, University of Belgrade, Dr. Subotica 4/2, 11000 Belgrade (Serbia); Rakocevic, Zlatko, E-mail: zlatkora@vinca.rs [Laboratory for Atomic Physics, Institute of Nuclear Sciences “Vinca”, University of Belgrade, Belgrade (Serbia)

    2014-08-30

    Graphical abstract: - Highlights: • Surface free energy and surface roughness influence bacterial adhesion. • Bacterial colonization causes periimplantitis and implant loss. • Zinc-based, glass-ionomers and resin-cements were investigated. • Glass-ionomers-cements present the lowest values of surface free energy and roughness. • Glass-ionomer-cements surface properties result with reduced bacterial adhesion. - Abstract: Background: Material surface free energy and surface roughness strongly influence the bacterial adhesion in oral cavity. The aim of this study was to analyze these two parameters in various commercial luting agents used for cementation of implant restorations. Materials and methods: Zinc-based, glass-ionomers, resin modified glass-ionomer and resin-cements were investigated. Contact angle and surface free energy were measured by contact angle analyzer using Image J software program. Materials’ average roughness and fractal dimension were calculated based on Atomic Force Microscope topography images. Results: Zinc phosphate cements presented significantly higher total surface free energy and significantly lower dispersive component of surface free energy compared to other groups, while resin-cements showed significantly lower polar component than other groups. The surface roughness and fractal dimension values were statistically the highest in the zinc phosphate cements and the lowest for the glass-ionomers cements. Conclusion: Glass-ionomers-cements presented lower values of surface free energy and surface roughness than zinc phosphate and resin cements, indicating that their surfaces are less prone to biofilm adhesion. Practical implications: Within limitations of an in vitro trial, our results indicate that glass-ionomers-cements could be the cements of choice for fixation of cement retained implant restorations due to superior surface properties compared to zinc phosphate and resin cements, which may result in reduced plaque formation

  5. 水泥中放射性物质与比活度%Radioactive Material and Radionuclide Than Activity in Cement

    Institute of Scientific and Technical Information of China (English)

    秦宗会; 唐博; 谢兵; 高兵

    2011-01-01

    Radioactive pollution was the main mode of environmental contamination of building materials.Cement and cement products was one of the important radioactive sources of construction materials.Radioactive contamination of building materials was serious harm for human health in their daily work and life and therefore the cement and cement related products in the radioactive pollution needed to be focued on and discussed.The types of radioactive contaminants in cement and their impact on the health hazards were mainly discussed,the content of the main radioactive materials in cement products of our country were analyzed and the national standards were compared to,understand the existing cement products,radioactive material impact on the human body.%放射性污染是建筑材料主要的环境污染方式之一,水泥以及水泥制品是建筑材料中重要的放射性污染源之一。建筑材料的放射性污染会在日常的工作和生活中严重危害人体的健康,故而水泥以及水泥相关制品中的放射性污染需要重点关注和讨论。本文主要讨论水泥中放射性污染物质的种类以及其对人体的危害,同时对我国水泥产品中主要放射性物质的含量进行分析,对比国家相关标准,了解现有水泥产品中放射性物质对人体的影响程度。

  6. Minimally invasive maxillofacial vertical bone augmentation using brushite based cements

    NARCIS (Netherlands)

    Tamimi, Faleh; Torres, Jesus; Lopez-Cabarcos, Enrique; Bassett, David C.; Habibovic, Pamela; Luceron, Elena; Barralet, Jake E.

    2009-01-01

    An ideal material for maxillofacial vertical bone augmentation procedures should not only be osteoconductive, biocompatible and mechanically strong, but should also be applied using minimally invasive procedures and remain stable with respect to the original bone surfaces. This way, implant exposure

  7. Cement-based composites: Strain rate effects on fracture

    Energy Technology Data Exchange (ETDEWEB)

    Mindess, S.; Shah, S.P.

    1986-01-01

    This book contains over 20 selections. Some of the titles are: Continuum damage mechanics studies on the dynamic fracture of concrete; Dynamic compressive strength of cementitious materials; Rate-sensitivity of mode I and mode II fracture concrete; and An impact damage model of concrete.

  8. Study on the effects of white rice husk ash and fibrous materials additions on some properties of fiber-cement composites.

    Science.gov (United States)

    Hamzeh, Yahya; Ziabari, Kamran Pourhooshyar; Torkaman, Javad; Ashori, Alireza; Jafari, Mohammad

    2013-03-15

    This work assesses the effects of white rice husk ash (WRHA) as pozzolanic material, virgin kraft pulp (VKP), old corrugated container (OCC) and fibers derived from fiberboard (FFB) as reinforcing agents on some properties of blended cement composites. In the sample preparation, composites were manufactured using fiber-to-cement ratio of 25:75 by weight and 5% CaCl(2) as accelerator. Type II Portland cement was replaced by WRHA at 0%, 25% and 50% by weight of binder. A water-to-binder ratio of 0.55 was used for all blended cement paste mixes. For parametric study, compressive strength, water absorption and density of the composite samples were evaluated. Results showed that WRHA can be applied as a pozzolanic material to cement and also improved resistance to water absorption. However, increasing the replacement level of WRHA tends to reduce the compressive strength due to the low binding ability. The optimum replacement level of WRHA in mortar was 25% by weight of binder; this replacement percentage resulted in better compressive strengths and water absorption. OCC fiber is shown to be superior to VKF and FFB fibers in increasing the compressive strength, due to its superior strength properties. As expected, the increase of the WRHA content induced the reduction of bulk density of the cement composites. Statistical analysis showed that the interaction of above-mentioned variable parameters was significant on the mechanical and physical properties at 1% confidence level.

  9. Effect of carbon nanotubes on properties of cement-sand-based piezoelectric composites

    Science.gov (United States)

    Kim, Sunjung; Zhao, Ping; Enemuoh, Emmanuel

    2015-04-01

    Carbon Nanotubes (CNTs) were dispersed in a cement-sand-based piezoelectric smart composite as conductive fillers to improve its poling efficiency, leading to a desirable piezoelectric effect. By introducing a small amount of CNTs, continuous electric networks between Lead Zirconate Titanate (PZT) particles were created, thus making the composite poling easier. Specimens were prepared by mixing PZT powders, Portland cement and sand with CNTs, followed by pressing it with a load frame system. The effect of quantity of CNTs ranging from 0 to 1.0 volume percent on properties of the composite, including its piezoelectric coefficient, dielectric constant and loss, and sensing effects, were characterized. It was found that the addition of CNTs facilitated effective poling at room temperature and improved the piezoelectric and dielectric properties of the composite. The composite modified by CNTs achieved optimal properties when the CNTs content was 0.7 vol.%.

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

    OpenAIRE

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

    2014-01-01

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

  11. Model of Coherent Interface Formation in Cement-Based Composites Containing Polyblend of Polyvinyl Alcohol and Methylcellulose

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The texture of interfacial zone between cement paste and quartz in the cement-based composites containing polyvinyl alcohol (PVA),methylcellulose (MC) and their polyblend in an amount of 10 wt % with respect to cement,as well as the texture of dehydrated bodies of PVA,MC,and the polyblend solutions,were investigated with SEM.The network texture of the dehydrated polyblend is confirmed by comparing the texture of dehydrated bodies of PVA and MC.The network texture has restrained the movement of polyblend molecules in the cement mortar but is helpful to forming a coherent interface between cement paste and quartz.The key factor of forming the coherent interface is not the neutralization reaction between H+ from hydrolysis of quartz and OH- from hydration of cement,but the electrostatic attraction and the chemical reaction between polar groups on the polyblend molecule and cations and anions from hydrolysis of quartz and hydration of cement,respectively.The model of the coherent interface formation is that excessive [HSiO3]- and [SiO3]2- anions are bonded with the hydrated cations such as Ca2+ and Al3+,which is confirmed by the gel containing Ca and Si on the quartz surface.

  12. Material properties and in vitro biocompatibility of a newly developed bone cement

    Directory of Open Access Journals (Sweden)

    Elke Mitzner

    2009-01-01

    Full Text Available In this study mechanical properties and biocompatibility (In Vitro of a new bone cement were investigated. A new platform technology named COOL is a variable composite of dissolved, chemically modified PMMA and different bioceramics. COOL cures at body temperature via a classical cementation reaction. Compressive strengths ranging from 3.6 ± 0.8 to 62.8 ± 1.3 MPa and bending strengths ranging from 9.9 ± 2.4 to 26.4 ± 3.0 MPa were achieved with different COOL formulations. Porosity varied between 31 and 43%. Varying the components of each formulation mechanical properties and porosity could be adjusted. In Vitro biocompatibility studies with primary human osteoblasts (pHOB in direct contact with different COOL formulations, did not reveal any signs of toxicity. In contrast to Refobacin® R, cells incubated with COOL showed similar density, viability and ALP activity compared to control, if specimen were added immediately to the cell monolayer after preparation. In conclusion, COOL has promising mechanical properties in combination with high biocompatibility In Vitro and combines different advantages of both CPCs and PMMA cements by avoiding some of the respective shortcomings.

  13. Observation and quantification of water penetration into Strain Hardening Cement-based Composites (SHCC) with multiple cracks by means of neutron radiography

    Science.gov (United States)

    Zhang, P.; Wittmann, F. H.; Zhao, T. J.; Lehmann, E. H.; Tian, L.; Vontobel, P.

    2010-08-01

    Durability of reinforced concrete structures has become a crucial issue with respect to economy, ecology and sustainability. One major reason for durability problems of concrete structures is the limited strain capacity of cement-based materials under imposed tensile stress. By adding PVA fibers, a new material named Strain Hardening Cement-based Composites (SHCC) with high strain capacity can be produced. Due to the formation of multiple micro-cracks, wide cracks can be avoided in SHCC under an imposed strain. The high strain capacity, however, is beneficial with respect to durability only if the multi-crack formation in SHCC does not lead to significantly increased water penetration. If water and aggressive chemical compounds such as chlorides and sulfates dissolved in water penetrate into the cement-based matrix and reach the steel reinforcement service-life of reinforced concrete structures will be reduced significantly. In this project, neutron radiography was applied to observe and quantify the process of water penetration into uncracked SHCC and after the multi-crack formation. In addition, water penetration into integral water repellent cracked and uncracked SHCC, which has been produced by adding a silane-based water repellent agent to the fresh SHCC mortar has been investigated. Results will be discussed with respect to durability.

  14. Observation and quantification of water penetration into Strain Hardening Cement-based Composites (SHCC) with multiple cracks by means of neutron radiography

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, P. [Center for Durability and Sustainability Studies of Shandong Province, Qingdao Technological University, Qingdao 266033 (China); Wittmann, F.H., E-mail: wittmann@aedificat.d [Center for Durability and Sustainability Studies of Shandong Province, Qingdao Technological University, Qingdao 266033 (China); Aedificat Institute Freiburg, D-79100 Freiburg (Germany); Zhao, T.J. [Center for Durability and Sustainability Studies of Shandong Province, Qingdao Technological University, Qingdao 266033 (China); Lehmann, E.H. [Department of Spallation Neutron Source (ASQ), Paul Scherrer Institute (PSI), CH-5232 Villigen (Switzerland); Tian, L. [Center for Durability and Sustainability Studies of Shandong Province, Qingdao Technological University, Qingdao 266033 (China); Vontobel, P. [Department of Spallation Neutron Source (ASQ), Paul Scherrer Institute (PSI), CH-5232 Villigen (Switzerland)

    2010-08-21

    Durability of reinforced concrete structures has become a crucial issue with respect to economy, ecology and sustainability. One major reason for durability problems of concrete structures is the limited strain capacity of cement-based materials under imposed tensile stress. By adding PVA fibers, a new material named Strain Hardening Cement-based Composites (SHCC) with high strain capacity can be produced. Due to the formation of multiple micro-cracks, wide cracks can be avoided in SHCC under an imposed strain. The high strain capacity, however, is beneficial with respect to durability only if the multi-crack formation in SHCC does not lead to significantly increased water penetration. If water and aggressive chemical compounds such as chlorides and sulfates dissolved in water penetrate into the cement-based matrix and reach the steel reinforcement service-life of reinforced concrete structures will be reduced significantly. In this project, neutron radiography was applied to observe and quantify the process of water penetration into uncracked SHCC and after the multi-crack formation. In addition, water penetration into integral water repellent cracked and uncracked SHCC, which has been produced by adding a silane-based water repellent agent to the fresh SHCC mortar has been investigated. Results will be discussed with respect to durability.

  15. Low pH Cements

    Energy Technology Data Exchange (ETDEWEB)

    Savage, David; Benbow, Steven [Quintessa Ltd., Henley-on-Thames (United Kingdom)

    2007-05-15

    The development of low-pH cements for use in geological repositories for radioactive waste stems from concerns over the potential for deleterious effects upon the host rock and other EBS materials (notably bentonite) under the hyperalkaline conditions (pH > 12) of cement pore fluids. Low pH cement (also known as low heat cement) was developed by the cement industry for use where large masses of cement (e.g. dams) could cause problems regarding heat generated during curing. In low pH cements, the amount of cement is reduced by substitution of materials such as fly ash, blast furnace slag, silica fume, and/or non-pozzolanic silica flour. SKB and Posiva have ruled out the use of blast furnace slag and fly-ash and are focusing on silica fume as a blending agent. Currently, no preferred composition has been identified by these agencies. SKB and Posiva have defined a pH limit {<=} 11 for cement grout leachates. To attain this pH, blending agents must comprise at least 50 wt % of dry materials. Because low pH cement has little, or no free portlandite, the cement consists predominantly of calcium silicate hydrate (CSH) gel with a Ca/Si ratio {<=} 0.8. Although there are potential implications for the performance of the spent fuel and cladding due to the presence of hyperalkaline fluids from cement, the principal focus for safety assessment lies with the behaviour of bentonite. There are a number of potential constraints on the interaction of hyperalkaline cement pore fluids with bentonite, including mass balance, thermodynamic issues, mass transport, and kinetics, but none of these is likely to be limiting if conventional OPC cements are employed in repository construction. Nevertheless: Low-pH cements may supply approximately 50 % less hydroxyl ions than conventional OPC for a given volume of cement, but mass balance constraints are complicated by the uncertainty concerning the type of secondary minerals produced during cement-bentonite interaction. The change of aqueous

  16. Low pH Cements

    Energy Technology Data Exchange (ETDEWEB)

    Savage, David; Benbow, Steven [Quintessa Ltd., Henley-on-Thames (United Kingdom)

    2007-05-15

    The development of low-pH cements for use in geological repositories for radioactive waste stems from concerns over the potential for deleterious effects upon the host rock and other EBS materials (notably bentonite) under the hyperalkaline conditions (pH > 12) of cement pore fluids. Low pH cement (also known as low heat cement) was developed by the cement industry for use where large masses of cement (e.g. dams) could cause problems regarding heat generated during curing. In low pH cements, the amount of cement is reduced by substitution of materials such as fly ash, blast furnace slag, silica fume, and/or non-pozzolanic silica flour. SKB and Posiva have ruled out the use of blast furnace slag and fly-ash and are focusing on silica fume as a blending agent. Currently, no preferred composition has been identified by these agencies. SKB and Posiva have defined a pH limit {<=} 11 for cement grout leachates. To attain this pH, blending agents must comprise at least 50 wt % of dry materials. Because low pH cement has little, or no free portlandite, the cement consists predominantly of calcium silicate hydrate (CSH) gel with a Ca/Si ratio {<=} 0.8. Although there are potential implications for the performance of the spent fuel and cladding due to the presence of hyperalkaline fluids from cement, the principal focus for safety assessment lies with the behaviour of bentonite. There are a number of potential constraints on the interaction of hyperalkaline cement pore fluids with bentonite, including mass balance, thermodynamic issues, mass transport, and kinetics, but none of these is likely to be limiting if conventional OPC cements are employed in repository construction. Nevertheless: Low-pH cements may supply approximately 50 % less hydroxyl ions than conventional OPC for a given volume of cement, but mass balance constraints are complicated by the uncertainty concerning the type of secondary minerals produced during cement-bentonite interaction. The change of aqueous

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

    OpenAIRE

    2015-01-01

    Cement production contributes to extensive CO2 emissions. However, the climate impact can vary significantly between different production systems and different types of cement products. The market is dominated by ordinary Portland cement, which is based on primary raw materials and commonly associated with combustion of vast amounts of fossil fuels. Therefore, the production of Portland cement can be described as a rather linear process. But there are alternative options, for example, involvi...

  18. Thermo-hydro-mechanical modeling and analysis of cement-based energy storages for small-scale dwellings

    Science.gov (United States)

    Hailemariam, Henok; Wuttke, Frank

    2016-04-01

    One of the common technologies for balancing the energy demand and supply in district heating, domestic hot water production, thermal power plants and thermal process industries in general is thermal energy storage. Thermal energy storage, in particular sensible heat storage as compared to latent heat storage and thermo-chemical storage, has recently gained much interest in the renewable energy storage sector due to its comparatively low cost and technical development. Sensible heat storages work on the principle of storing thermal energy by raising or lowering the temperature of liquid (commonly water) or solid media, and do not involve material phase change or conversion of thermal energy by chemical reactions or adsorption processes as in latent heat and thermo-chemical storages, respectively. In this study, the coupled thermo-hydro-mechanical behaviour of a cement-based thermal energy storage system for domestic applications has been modeled in both saturated as well as unsaturated conditions using the Finite Element method along with an extensive experimental analysis program for parameter detection. For this purpose, a prototype model is used with three well-known thermal energy storage materials, and the temperature and heat distribution of the system were investigated under specific thermo-hydro-mechanical conditions. Thermal energy samples with controlled water to solids ratio and stored in water for up to 28 days were used for the experimental program. The determination of parameters included: thermal conductivity, specific heat capacity and linear coefficient of thermal expansion (CTE) using a transient line-source measurement technique as well as a steady-state thermal conductivity and expansion meter; mechanical strength parameters such as uni-axial strength, young's modulus of elasticity, poisson's ratio and shear parameters using uniaxial, oedometer and triaxial tests; and hydraulic properties such as hydraulic permeability or conductivity under

  19. A literature review of mixed waste components: Sensitivities and effects upon solidification/stabilization in cement-based matrices

    Energy Technology Data Exchange (ETDEWEB)

    Mattus, C.H.; Gilliam, T.M.

    1994-03-01

    The US DOE Oak Ridge Field Office has signed a Federal Facility Compliance Agreement (FFCA) regarding Oak Ridge Reservation (ORR) mixed wastes subject to the land disposal restriction (LDR) provisions of the Resource conservation and Recovery Act. The LDR FFCA establishes an aggressive schedule for conducting treatability studies and developing treatment methods for those ORR mixed (radioactive and hazardous) wastes listed in Appendix B to the Agreement. A development, demonstration, testing, and evaluation program has been initiated to provide those efforts necessary to identify treatment methods for all of the wastes that meet Appendix B criteria. The program has assembled project teams to address treatment development needs in a variety of areas, including that of final waste forms (i.e., stabilization/solidification processes). A literature research has been performed, with the objective of determining waste characterization needs to support cement-based waste-form development. The goal was to determine which waste species are problematic in terms of consistent production of an acceptable cement-based waste form and at what concentrations these species become intolerable. The report discusses the following: hydration mechanisms of Portland cement; mechanisms of retardation and acceleration of cement set-factors affecting the durability of waste forms; regulatory limits as they apply to mixed wastes; review of inorganic species that interfere with the development of cement-based waste forms; review of radioactive species that can be immobilized in cement-based waste forms; and review of organic species that may interfere with various waste-form properties.

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

    OpenAIRE

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

    2014-01-01

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

  1. Apical Sealing Ability of Mineral Trioxide Aggregate, Intermediate Restorative Material and Calcium Enriched Mixture Cement: A Bacterial Leakage Study

    Science.gov (United States)

    Shahriari, Shahriar; Faramarzi, Farhad; Alikhani, Mohammad-Yousef; Farhadian, Maryam; Hendi, Seyedeh Sareh

    2016-01-01

    Introduction: This in vitro study compared the apical sealing ability of three common root end filling materials namely mineral trioxide aggregate (MTA), intermediate restorative material (IRM) and calcium-enriched mixture (CEM) cement using a bacterial leakage model. Methods and Materials: The study was conducted on 83 single-rooted human teeth. Tooth crowns were cut and root canals were prepared using the step-back technique. Apical 3 mm of the roots were cut and a three-mm-deep cavity was prepared using an ultrasonic instrument. The samples were divided into three groups (n=25) according to the root-end filling material including MTA, IRM and CEM cement. The roots were inserted into cut-end microtubes. After sterilization with ethylene oxide, microtubes were placed in sterile vials containing 10 mL of Brain Heart Infusion (BHI) broth and incubated at 37°C and 0.1 mL of Enterococcus faecalis suspension compatible with 0.5 McFarland standard (1.5×108 cell/ ml), which was refreshed daily. This procedure was continued for 70 days. The data were analyzed using the chi-square, Kruskal-Wallis and log rank tests. The level of significance was set at 0.05. Results: No significant difference was found in bacterial microleakage among three groups; MTA showed slightly (but not significantly) less microleakage than IRM and CEM. However, the difference in the mean time of microleakage was significant among the groups (P<0.04) and in MTA samples leakage occurred in a longer time than CEM (P<0.012). Conclusion: The three tested root end filling materials had equal sealing efficacy for preventing bacterial leakage. PMID:27790267

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-15

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

  3. Advances in glass-ionomer cements

    OpenAIRE

    Davidson, Carel Leon

    2006-01-01

    This article describes the properties, advances and shortcomings of glass-ionomer cement as a restorative material. The adhesion of glass-ionomer to tooth structure is less technique sensitive than composite resins and its quality increases with time. Therefore glass-ionomer might turn out to the more reliable restorative material in minimal invasive dentistry based on adhesive techniques.

  4. Advances in glass-ionomer cements.

    Science.gov (United States)

    Davidson, Carel Leon

    2006-01-01

    This article describes the properties, advances and shortcomings of glass-ionomer cement as a restorative material. The adhesion of glass-ionomer to tooth structure is less technique sensitive than composite resins and its quality increases with time. Therefore glass-ionomer might turn out to the more reliable restorative material in minimal invasive dentistry based on adhesive techniques.

  5. Mechanical Behavior and Thermal Stability of Acid-Base Phosphate Cements and Composites Fabricated at Ambient Temperature

    Science.gov (United States)

    Colorado Lopera, Henry Alonso

    This dissertation presents the study of the mechanical behavior and thermal stability of acid-base phosphate cements (PCs) and composites fabricated at ambient temperature. These materials are also known as chemically bonded phosphate ceramics (CBPCs). Among other advantages of using PCs when compared with traditional cements are the better mechanical properties (compressive and flexural strength), lower density, ultra-fast (controllable) setting time, controllable pH, and an environmentally benign process. Several PCs based on wollastonite and calcium and alumino phosphates after thermal exposure up to 1000°C have been investigated. First, the thermo-mechanical and chemical stability of wollastonite-based PC (Wo-PC) exposed to temperatures up to 1000°C in air environment were studied. The effects of processing conditions on the curing and shrinkage of the wollastonite-based PC were studied. The chemical reactions and phase transformations during the fabrication and during the thermal exposure are analyzed in detail using scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermo-gravimetric analysis (TGA Then, the thermo-mechanical and chemical stability of glass, carbon and basalt fiber reinforced Wo-PC composites, were studied using SEM, XRD, TGA. The flexural strength and Weibull statistics were analyzed. A significant strength degradation in the composites were found after the thermal exposure at elevated temperatures due to the interdifusion and chemical reactions across the fibers and the matrix at temperatures over 600°C. To overcome this barrier, we have developed a new PC based on calcium and alumino-phosphates (Ca-Al PCs). The Ca-Al PCs were studied in detail using SEM, XRD, TGA, curing, shrinkage, Weibull statistics, and compression tests. Our study has confirmed that this new composite material is chemically and mechanically stable at temperatures up to 1000°C. Moreover, the compression strength increases after exposure to 1000

  6. HYDRAULIC AND LEACHING BEHAVIOUR OF BELITE CEMENTS PRODUCED WITH ELECTRIC ARC FURNACE STEEL SLAG AS RAW MATERIAL

    Directory of Open Access Journals (Sweden)

    Iacobescu R. I.

    2013-06-01

    Full Text Available Three belite-rich cements consisting of a clinker made with 0 (BC, 5 (BC5 and 10 wt. % (BC10 electric arc furnace steel slag (EAFS as raw material, were studied for their hydraulic and leaching behaviour. Hydration behaviour was studied by FTIR, TG/DTG and SEM analyses. The cements with EAFS resulted in a higher C2S/C3S and C4AF/C3A ratio compared to the reference body. As a result, the rate of hydration was low at early days whereas the structure was porous with scattered AFm and C–S–H crystals. At 28 days, a comparable dense microstructure consisting largely of C–S–H is observed in all mortars. Leaching was studied for V and Cr by means of tank test according to standard NEN 7345. The results showed V release below 2 μg/l. Chromium release calculated per 24 h was 1.4 μg/l in BC5 and 2.4 μg/l in BC10, which is much lower than the parametric value of 50 μg/l specified by the European Directive for drinking water (98/83/EC.

  7. Study on properties of rice husk ash and its use as cement replacement material

    Directory of Open Access Journals (Sweden)

    Ghassan Abood Habeeb

    2010-06-01

    Full Text Available This paper investigates the properties of rice husk ash (RHA produced by using a ferro-cement furnace. The effect of grinding on the particle size and the surface area was first investigated, then the XRD analysis was conducted to verify the presence of amorphous silica in the ash. Furthermore, the effect of RHA average particle size and percentage on concrete workability, fresh density, superplasticizer (SP content and the compressive strength were also investigated. Although grinding RHA would reduce its average particle size (APS, it was not the main factor controlling the surface area and it is thus resulted from RHA's multilayered, angular and microporous surface. Incorporation of RHA in concrete increased water demand. RHA concrete gave excellent improvement in strength for 10% replacement (30.8% increment compared to the control mix, and up to 20% of cement could be valuably replaced with RHA without adversely affecting the strength. Increasing RHA fineness enhanced the strength of blended concrete compared to coarser RHA and control OPC mixtures.

  8. Sorption of Arsenic from Drinking Water to Mg(OH)2 Sorrel's Cements, and Zirconium Doped Materials

    Energy Technology Data Exchange (ETDEWEB)

    MOORE, ROBERT C.; ZHAO, HONGTING; SANCHEZ, CHARLES ANTHONY; HOLT, KATHLEEN C.; SALAS, FRED; HASAN, AHMED ALI MOHAMED; LUCERO, DANIEL A.

    2002-11-01

    It was discovered that MgO or Mg(OH){sub 2} when it reacts with water is a very strong sorbent for arsenic. Distribution constants, or K{sub d} values, are as high as 1 x 10{sup 6} L/mole. In this work, Mg(OH){sub 2} and other compounds have been investigated as sorbents for arsenic and other contaminants. This work has resulted in several major accomplishments including: (1) design, construction, and testing of a pressure sand filter to remove Mg(OH){sub 2} after it has sorbed arsenic from water, (2) stabilization of Mg(OH){sub 2} as a Sorrel's cement against reaction with carbonate that results in MgCO{sub 3} formation decreasing the efficiency of Mg(OH){sub 2} to sorb arsenic, and (3) the development of a new, very promising sorbent for arsenic based on zirconium. Zirconium is an environmentally benign material found in many common products such as toothpaste. It is currently used in water treatment and is very inexpensive. In this work, zirconium has been bonded to activated carbon, zeolites, sand and montmorillonite. Because of its high charge in ionic form (+6), zirconium is a strong sorbent for many anions including arsenic. In equilibrium experiments arsenic concentrations in water were reduced from 200 ppb to less than 1 ppb in less than 1 minute of contact time. Additionally, analytical methods for detecting arsenic in water have also been investigated. Various analytical techniques including HPLC, AA and ICP-MS are used for quantification of arsenic. Due to large matrix interferences HPLC and AA techniques are not very selective and are time consuming. ICP-MS is highly efficient, requires a low sample volume and has a high tolerance for interferences. All these techniques are costly and require trained staff, and with the exception of ICP-MS, these methods cannot be used at low ppb arsenic concentration without using a pre-concentration step. An alternative to these traditional techniques is to use a colorimetric method based on leucocrystal violet

  9. To what extent does the longevity of fixed dental prostheses depend on the function of the cement? Working Group 4 materials : cementation

    NARCIS (Netherlands)

    Edelhoff, Daniel; Ozcan, Mutlu

    2007-01-01

    Aims/Background: The objective of this review was to define the impact of cementation mode on the longevity of different types of single tooth restorations and fixed dental prostheses (FDP). Methods: Literature search by PubMed as the major database was used utilizing the terms namely, adhesive tech

  10. Development of a novel aluminum-free glass ionomer cement based on magnesium/strontium-silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong-Ae [Department of Biomaterials Science, College of Dentistry, Dankook University, Cheonan 330-714 (Korea, Republic of); Department of Nanobiomedical Science and BK21 Plus NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Cheonan 330-714 (Korea, Republic of); Abo-Mosallam, Hany A. [Glass Research Department, National Research Centre, Dokki, Cairo (Egypt); Lee, Hye-Young [Department of Nanobiomedical Science and BK21 Plus NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Cheonan 330-714 (Korea, Republic of); Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 330-714 (Korea, Republic of); Kim, Gyu-Ri [Department of Biomaterials Science, College of Dentistry, Dankook University, Cheonan 330-714 (Korea, Republic of); Department of Nanobiomedical Science and BK21 Plus NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Cheonan 330-714 (Korea, Republic of); Kim, Hae-Won [Department of Biomaterials Science, College of Dentistry, Dankook University, Cheonan 330-714 (Korea, Republic of); Department of Nanobiomedical Science and BK21 Plus NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Cheonan 330-714 (Korea, Republic of); Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 330-714 (Korea, Republic of); Lee, Hae-Hyoung, E-mail: haelee@dku.edu [Department of Biomaterials Science, College of Dentistry, Dankook University, Cheonan 330-714 (Korea, Republic of); Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 330-714 (Korea, Republic of)

    2014-09-01

    The effects of strontium substitution for magnesium in a novel aluminum-free multicomponent glass composition for glass ionomer cements (GICs) were investigated. A series of glass compositions were prepared based on SiO{sub 2}-P{sub 2}O{sub 5}-CaO-ZnO-MgO{sub (1-X)}-SrO{sub X}-CaF{sub 2} (X = 0, 0.25, 0.5 and 0.75). The mechanical properties of GICs prepared were characterized by compressive strength, flexural strength, flexural modules, and microhardness. Cell proliferation was evaluated indirectly by CCK-8 assay using various dilutions of the cement and rat mesenchyme stem cells. Incorporation of strontium instead of magnesium in the glasses has a significant influence on setting time of the cements and the properties. All mechanical properties of the GICs with SrO substitution at X = 0.25 were significantly increased, then gradually decreased with further increase of the amount of strontium substitution in the glass. The GIC at X = 0.25, also, showed an improved cell viability at low doses of the cement extracts in comparison with other groups or control without extracts. The results of this study demonstrate that the glass compositions with strontium substitution at low levels can be successfully used to prepare aluminum-free glass ionomer cements for repair and regeneration of hard tissues. - Highlights: • We developed multicomponent glass compositions for a novel aluminum-free glass ionomer cement (GIC). • The effects of MgO replacement with SrO in the glasses on the mechanical properties and cell proliferation were evaluated. • Substitution of MgO with SrO at low levels led to improvement of mechanical properties and cell viability of the cements. • Microstructural degradations in the cement matrix of the GICs with strontium at high levels were observed after aging.

  11. Comparison of one-dimensional and two-dimensional functionally graded materials for the backing shell of the cemented acetabular cup.

    Science.gov (United States)

    Hedia, H S

    2005-08-01

    Among the factors that have been suggested as contributing to the failure of a total joint replacement are stress shielding and the subsequent bone resorption. Recent studies have shown that when a backing shell made from a Ti alloy is used, high stresses are generated in the cement at the edges of the cup, and low stresses are generated at the dome of the bone in the acetabulum; thus, the bone at the dome suffers stress shielding and the cement edge suffers high stresses. The aim of this study was to investigate the effect of using a functionally graded material (FGM), instead of Ti alloy, for the backing shell (BS) on the stress distribution in the BS-cement-bone system. Finite-element and optimization techniques were used to obtain the optimal distribution of materials in the tangential direction only of the backing (1D FGM) as well as in the tangential and radial directions of the backing (2D FGM). It was found that the stress distribution in the BS-cement-bone system was about the same, regardless of whether the BS was fabricated from a 1D or 2D FGM. The stress-shielding factor in the bone at the dome of the acetabulum and the maximum von Mises stress in cement at the cement interfaces for 1D and 2D FGM were reduced by about 51%, 69%, and 50%, respectively, compared to the case when the shell was fabricated from a Ti alloy. The optimal elastic modulus of the 1D FGM was obtained with the materials graded from HA at the dome of the acetabulum to a Ti alloy at the rim of the shell. The optimal elastic modulus of the 2D FGM was obtained with the materials graded from Ti alloy at the right edge of the rim, to Bioglass 45S5 at the left edge of the rim, and to HA at the dome of the shell.

  12. Natural Radionuclide Contents in Raw Materials and the Aggregate Finished Product from Dangote Cement Plc, Obajana, Kogi State, North Central Nigeria

    Directory of Open Access Journals (Sweden)

    J.O. Ajayi

    2012-11-01

    Full Text Available Assessment of gamma ray activity in raw materials and the end product in Dangote Cement from Dangote Cement Plc, Obajana and Kogi State has been investigated in this study. Gamma ray spectrometry that possesses scintillation detector was used to analyze the samples collected from the company. Samples collected as raw materials are limestone, clay, gypsum and laterite and cement as finished product. The 40K, 238U, 232Th activity concentration were detected. The concentration of 40K range from 4649±366 to 0±65 Bq/Kg with highest value in limestone and lowest in laterite. The 238U concentration is highest in gypsum range from 696±233 to 41±27 Bq/Kg in laterite. 232Th activity is below detectable limit in all the raw materials but it has activity concentration of 40±26 Bq/Kg in the finished product which may be traceable to the fact that some finished additives are present which are not in the basic raw materials of this cement under investigation. It is concluded that the natural radionuclide measured for 40K, 238U and 232Th has mean activities of 2189.75±219.5, 331.25±132.25 and 0±31 Bq/Kg respectively, while its corresponding mean absorbed dose rate in air at 1 m above the ground was calculated to be 235.61 nGy/h or 2.064 mSv/y and the aggregate finished product (cement has absorbed dose rate of 342.22 nGy/h and an effective dose equivalent of 2.998 mSv/y. The calculated absorbed doses in nGy/h and mSv/y shows that Dangote cement under consideration has higher activities of the isotopes than the permissible level suggested by ICRP (80 nGy/h or 0.7 mSv/y

  13. Abnormal gradient microstructure in Cr3C2 based cemented carbide

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    With OLYMPUS PMG3 metallograph, an abnormal throe-layer gradient structure , i. e. coarsegrain zone, binder enrichment zone and normal structure zone from surface to inner, was observed in Cr3C2based cemented carbide. In the binder enrichment zone, three different shapes of anomalous coarse carbideswere observed. It is shown that the transverse rapture strength can be raised remarkably, up 20.7% from thealloy with abnormal gradient structure by removing the abnormal gradient structure. The results suggested thatthe abnormal gradient structure in the surface, especially the anomalous coarse carbides in the binder enrichment zone is the mair reason for the lower strength.

  14. ALKALI-ACTIVATED CEMENT MORTARS CONTAINING RECYCLED CLAY-BASED CONSTRUCTION AND DEMOLITION WASTE

    OpenAIRE

    Puertas, F.; Santos, R.; Alonso M. M.; Del Rio M.

    2015-01-01

    The use of clay-based waste as an aggregate for concrete production is an amply studied procedure. Nonetheless, research on the use of this recycled aggregate to prepare alkaline cement mortars and concretes has yet to be forthcoming. The present study aimed to determine: the behaviour of this waste as a pozzolan in OPC systems, the mechanical strength in OPC, alkali-activated slag (AAS) and fly ash (AAFA) mortars and the effect of partial replacement of the slag and ash themselves with groun...

  15. Investigation of Phosphate Cement-based Binder with Super High Early Strength for Repair of Concrete

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Magnesium phosphate cement-based binder (MPB) for repair of concrete was prepared by proportionally mixing over burned MgO powder (M) with NHH2PO4 powder (P) and set modifying admixtures. It is characteristic by excellent properties such as rapid setting,high strength and high bond strength to old concrete.. The study is focused on the key factors influencing the setting time and strength of MPB, the bond property of MPB to old concrete and the kinetic feature of the hydration of MPB.

  16. Possibility of Using Wood Pulp in the Preparation of Cement Composites

    Science.gov (United States)

    Kidalova, Lucia; Stevulova, Nadezda; Geffert, Anton

    2014-06-01

    Sustainable building materials are based on the use of renewable materials instead of non-renewable. Large group of renewable materials composes of plant fibres having high tensile strength are used as fillers into building material with reinforcement function of composite. This study aimed to establish the mechanical and physical properties of cement composites with organic fillers, such as wood pulp. Wood pulp cellulose is very interesting material as reinforcement in cement which contributes to a reduction of pollutants. Varying the producing technology (wood pulp and cement ratio in mixture) it is possible to obtain composites with density from 940 to 1260 kgm-3 and with compressive strength from 1.02 to 5.44 MPa after 28 days of hardening. Based on the experimental results, cement composites with using unbleached wood pulp reach higher values than composites based on bleached wood pulp. Volume ratio of unbleached wood pulp in composites influences water absorbability of cement composites

  17. Possibility of Using Wood Pulp in the Preparation of Cement Composites

    Directory of Open Access Journals (Sweden)

    Kidalova Lucia

    2014-06-01

    Full Text Available Sustainable building materials are based on the use of renewable materials instead of non-renewable. Large group of renewable materials composes of plant fibres having high tensile strength are used as fillers into building material with reinforcement function of composite. This study aimed to establish the mechanical and physical properties of cement composites with organic fillers, such as wood pulp. Wood pulp cellulose is very interesting material as reinforcement in cement which contributes to a reduction of pollutants. Varying the producing technology (wood pulp and cement ratio in mixture it is possible to obtain composites with density from 940 to 1260 kgm-3 and with compressive strength from 1.02 to 5.44 MPa after 28 days of hardening. Based on the experimental results, cement composites with using unbleached wood pulp reach higher values than composites based on bleached wood pulp. Volume ratio of unbleached wood pulp in composites influences water absorbability of cement composites

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

    Science.gov (United States)

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

    2011-12-01

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

  19. Predicting composition-property relationships for glass ionomer cements: a multifactor central composite approach to material optimization.

    Science.gov (United States)

    Kiri, Lauren; Boyd, Daniel

    2015-06-01

    Adjusting powder-liquid ratio (P/L) and polyacrylic acid concentration (AC) has been documented as a means of tailoring the handling and mechanical properties of glass ionomer cements (GICs). This work implemented a novel approach in which the interactive effects of these two factors on three key GIC properties (working time, setting time, and compressive strength) were investigated using a central composite design of experiments. Using nonlinear regression analysis, formulation-property relationships were derived for each property, which enabled prediction of an optimal formulation (P/L and AC) through application of the desirability approach. A novel aluminum free GIC was investigated, as this material may present the first clinically viable GIC for use in injectable spinal applications, such as vertebroplasty. Ultimately, this study presents the first series of predictive regression models that explain the formulation-dependence of a GIC, and the first statistical method for optimizing both P/L and AC depending on user-defined inputs.

  20. Cement-base bearing pads mortar for connections in the precast concrete: study of surface roughness

    Directory of Open Access Journals (Sweden)

    M. K. El Debs

    Full Text Available Bearing pads are used in precast concrete connections to avoid concentrated stresses in the contact area between the precast elements. In the present research, the bearing pads are Portland cement mortar with styrene-butadiene latex (SB, lightweight aggregate (expanded vermiculite-term and short fibers (polypropylene, glass and PVA, in order to obtain a material with low modulus of elasticity and high tenacity, compared with normal Portland cement mortar. The objective of this paper is to analyze the influence of surface roughness on the pads and test other types of polypropylene fibers. Tests were carried out to characterize the composite and test on bearing pads. Characterization tests show compressive strength of 41MPa and modulus of elasticity of 12.8GPa. The bearing pads tests present 30% reduction of stiffness in relation to a reference mortar. The bearing pads with roughness on both sides present a reduction up to 30% in stiffness and an increase in accumulated deformation of more than 120%, regarding bearing pads with both sides smooth.

  1. Development of nanosilica bonded monetite cement from egg shells

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Huan, E-mail: huanzhou@cczu.edu.cn [Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu (China); Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Luchini, Timothy J.F.; Boroujeni, Nariman Mansouri [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Agarwal, Anand K.; Goel, Vijay K. [Department of Bioengineering, The University of Toledo, Toledo, OH (United States); Bhaduri, Sarit B. [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Division of Dentistry, The University of Toledo, Toledo, OH (United States)

    2015-05-01

    This work represents further effort from our group in developing monetite based calcium phosphate cements (CPC). These cements start with a calcium phosphate powder (MW-CPC) that is manufactured using microwave irradiation. Due to the robustness of the cement production process, we report that the starting materials can be derived from egg shells, a waste product from the poultry industry. The CPC were prepared with MW-CPC and aqueous setting solution. Results showed that the CPC hardened after mixing powdered cement with water for about 12.5 ± 1 min. The compressive strength after 24 h of incubation was approximately 8.45 ± 1.29 MPa. In addition, adding colloidal nanosilica to CPC can accelerate the cement hardening (10 ± 1 min) process by about 2.5 min and improve compressive strength (20.16 ± 4.39 MPa), which is more than double the original strength. The interaction between nanosilica and CPC was monitored using an environmental scanning electron microscope (ESEM). While hardening, nanosilica can bond to the CPC crystal network for stabilization. The physical and biological studies performed on both cements suggest that they can potentially be used in orthopedics. - Highlights: • Cement raw powder is derived from egg shells. • A microwave assisted system is used for preparing monetite bone cement. • Colloidal silica is used to reinforce cement.

  2. Synthesis of a Cementitious Material Nanocement Using Bottom-Up Nanotechnology Concept: An Alternative Approach to Avoid CO2 Emission during Production of Cement

    Directory of Open Access Journals (Sweden)

    Byung Wan Jo

    2014-01-01

    Full Text Available The world’s increasing need is to develop smart and sustainable construction material, which will generate minimal climate changing gas during their production. The bottom-up nanotechnology has established itself as a promising alternative technique for the production of the cementitious material. The present investigation deals with the chemical synthesis of cementitious material using nanosilica, sodium aluminate, sodium hydroxide, and calcium nitrate as reacting phases. The characteristic properties of the chemically synthesized nanocement were verified by the chemical composition analysis, setting time measurement, particle size distribution, fineness analysis, and SEM and XRD analyses. Finally, the performance of the nanocement was ensured by the fabrication and characterization of the nanocement based mortar. Comparing the results with the commercially available cement product, it is demonstrated that the chemically synthesized nanocement not only shows better physical and mechanical performance, but also brings several encouraging impacts to the society, including the reduction of CO2 emission and the development of sustainable construction material. A plausible reaction scheme has been proposed to explain the synthesis and the overall performances of the nanocement.

  3. Effect of copolymer latexes on physicomechanical properties of mortar containing high volume fly ash as a replacement material of cement.

    Science.gov (United States)

    Negim, El-Sayed; Kozhamzharova, Latipa; Gulzhakhan, Yeligbayeva; Khatib, Jamal; Bekbayeva, Lyazzat; Williams, Craig

    2014-01-01

    This paper investigates the physicomechanical properties of mortar containing high volume of fly ash (FA) as partial replacement of cement in presence of copolymer latexes. Portland cement (PC) was partially replaced with 0, 10, 20, 30 50, and 60% FA. Copolymer latexes were used based on 2-hydroxyethyl acrylate (2-HEA) and 2-hydroxymethylacrylate (2-HEMA). Testing included workability, setting time, absorption, chemically combined water content, compressive strength, and scanning electron microscopy (SEM). The addition of FA to mortar as replacement of PC affected the physicomechanical properties of mortar. As the content of FA in the concrete increased, the setting times (initial and final) were elongated. The results obtained at 28 days of curing indicate that the maximum properties of mortar occur at around 30% FA. Beyond 30% FA the properties of mortar reduce and at 60% FA the properties of mortar are lower than those of the reference mortar without FA. However, the addition of polymer latexes into mortar containing FA improved most of the physicomechanical properties of mortar at all curing times. Compressive strength, combined water, and workability of mortar containing FA premixed with latexes are higher than those of mortar containing FA without latexes.

  4. Effect of Copolymer Latexes on Physicomechanical Properties of Mortar Containing High Volume Fly Ash as a Replacement Material of Cement

    Directory of Open Access Journals (Sweden)

    El-Sayed Negim

    2014-01-01

    Full Text Available This paper investigates the physicomechanical properties of mortar containing high volume of fly ash (FA as partial replacement of cement in presence of copolymer latexes. Portland cement (PC was partially replaced with 0, 10, 20, 30 50, and 60% FA. Copolymer latexes were used based on 2-hydroxyethyl acrylate (2-HEA and 2-hydroxymethylacrylate (2-HEMA. Testing included workability, setting time, absorption, chemically combined water content, compressive strength, and scanning electron microscopy (SEM. The addition of FA to mortar as replacement of PC affected the physicomechanical properties of mortar. As the content of FA in the concrete increased, the setting times (initial and final were elongated. The results obtained at 28 days of curing indicate that the maximum properties of mortar occur at around 30% FA. Beyond 30% FA the properties of mortar reduce and at 60% FA the properties of mortar are lower than those of the reference mortar without FA. However, the addition of polymer latexes into mortar containing FA improved most of the physicomechanical properties of mortar at all curing times. Compressive strength, combined water, and workability of mortar containing FA premixed with latexes are higher than those of mortar containing FA without latexes.

  5. Wide-scale utilization of MSWI fly ashes in cement production and its impact on average heavy metal contents in cements: The case of Austria.

    Science.gov (United States)

    Lederer, Jakob; Trinkel, Verena; Fellner, Johann

    2017-02-01

    A number of studies present the utilization of fly ashes from municipal solid waste incineration (MSWI) in cement production as a recycling alternative to landfilling. While there is a lot of research on the impact of MSWI fly ashes utilization in cement production on the quality of concrete or the leaching of heavy metals, only a few studies have determined the resulting heavy metal content in cements caused by this MSWI fly ashes utilization. Making use of the case of Austria, this study (1) determines the total content of selected heavy metals in cements currently produced in the country, (2) designs a scenario and calculates the resulting heavy metal contents in cements assuming that all MSWI fly ashes from Austrian grate incinerators were used as secondary raw materials for Portland cement clinker production and (3) evaluates the legal recyclability of demolished concretes produced from MSWI fly ash amended cements based on their total heavy metal contents. To do so, data from literature and statistics are combined in a material flow analysis model to calculate the average total contents of heavy metals in cements and in the resulting concretes according to the above scenario. The resulting heavy metal contents are then compared (i) to their respective limit values for cements as defined in a new technical guideline in Austria (BMLFUW, 2016), and (ii) to their respective limit values for recycling materials from demolished concrete. Results show that MSWI fly ashes utilization increases the raw material input in cement production by only +0.9%, but the total contents of Cd by +310%, and Hg, Pb, and Zn by +70% to +170%. However these and other heavy metal contents are still below their respective limit values for Austrian cements. The same legal conformity counts for recycling material derived from concretes produced from the MSWI fly ash cements. However, if the MSWI fly ash ratio in all raw materials used for cement production were increased from 0.9% to 22

  6. 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...

  7. Materials engineering data base

    Science.gov (United States)

    1995-01-01

    The various types of materials related data that exist at the NASA Marshall Space Flight Center and compiled into databases which could be accessed by all the NASA centers and by other contractors, are presented.

  8. Two-stage revision total hip arthroplasty for periprosthetic infections using antibiotic-impregnated cement spacers of various types and materials.

    Science.gov (United States)

    Uchiyama, Katsufumi; Takahira, Naonobu; Fukushima, Kensuke; Moriya, Mitsutoshi; Yamamoto, Takeaki; Minegishi, Yojiro; Sakai, Rina; Itoman, Moritoshi; Takaso, Masashi

    2013-01-01

    Antibiotic-impregnated hip cement spacers of various types and materials have been used in the treatment of periprosthetic hip infections. We developed a handmade spacer by using polymethylmethacrylate (PMMA) and/or α -tricalcium phosphate ( α -TCP). In this study, we retrospectively reviewed the surgical outcomes in 36 consecutive patients treated with 2-stage revision total hip arthroplasty by using our antibiotic-impregnated hip cement spacers. We aimed to analyze the infection control and reinfection rates after revision surgery. Moreover, we analyzed the possible predictors of postoperative reinfection. After exclusion of 1 patient who died immediately after the first-stage surgery, infection was controlled in 33 of the 36 hips (success rate, 91.7%). Two of these 33 hips underwent resection arthroplasty. Of the 36 hips that had been treated with the antibiotic-cement spacer, 31 hips (86.1%) were eligible for the second-stage prosthesis re-implantation. The 31 protocol hip joints of patients followed up for >6 months (mean, 48.6 months). Ten of these 31 hips (32.3%) became reinfected. No possible predictor examined differed significantly between the reinfection-positive and reinfection-negative groups. However, spacers consisting of PMMA cement alone were associated with the highest risk of reinfection. Therefore, α -TCP-containing antibiotic-impregnated hip cement spacers might decrease the reinfection rate in patients undergoing re-implantation.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-12-31

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

  10. Research on a Defects Detection Method in the Ferrite Phase Shifter Cementing Process Based on a Multi-Sensor Prognostic and Health Management (PHM) System.

    Science.gov (United States)

    Wan, Bo; Fu, Guicui; Li, Yanruoyue; Zhao, Youhu

    2016-08-10

    The cementing manufacturing process of ferrite phase shifters has the defect that cementing strength is insufficient and fractures always appear. A detection method of these defects was studied utilizing the multi-sensors Prognostic and Health Management (PHM) theory. Aiming at these process defects, the reasons that lead to defects are analyzed in this paper. In the meanwhile, the key process parameters were determined and Differential Scanning Calorimetry (DSC) tests during the cure process of resin cementing were carried out. At the same time, in order to get data on changing cementing strength, multiple-group cementing process tests of different key process parameters were designed and conducted. A relational model of cementing strength and cure temperature, time and pressure was established, by combining data of DSC and process tests as well as based on the Avrami formula. Through sensitivity analysis for three process parameters, the on-line detection decision criterion and the process parameters which have obvious impact on cementing strength were determined. A PHM system with multiple temperature and pressure sensors was established on this basis, and then, on-line detection, diagnosis and control for ferrite phase shifter cementing process defects were realized. It was verified by subsequent process that the on-line detection system improved the reliability of the ferrite phase shifter cementing process and reduced the incidence of insufficient cementing strength defects.

  11. Research on a Defects Detection Method in the Ferrite Phase Shifter Cementing Process Based on a Multi-Sensor Prognostic and Health Management (PHM System

    Directory of Open Access Journals (Sweden)

    Bo Wan

    2016-08-01

    Full Text Available The cementing manufacturing process of ferrite phase shifters has the defect that cementing strength is insufficient and fractures always appear. A detection method of these defects was studied utilizing the multi-sensors Prognostic and Health Management (PHM theory. Aiming at these process defects, the reasons that lead to defects are analyzed in this paper. In the meanwhile, the key process parameters were determined and Differential Scanning Calorimetry (DSC tests during the cure process of resin cementing were carried out. At the same time, in order to get data on changing cementing strength, multiple-group cementing process tests of different key process parameters were designed and conducted. A relational model of cementing strength and cure temperature, time and pressure was established, by combining data of DSC and process tests as well as based on the Avrami formula. Through sensitivity analysis for three process parameters, the on-line detection decision criterion and the process parameters which have obvious impact on cementing strength were determined. A PHM system with multiple temperature and pressure sensors was established on this basis, and then, on-line detection, diagnosis and control for ferrite phase shifter cementing process defects were realized. It was verified by subsequent process that the on-line detection system improved the reliability of the ferrite phase shifter cementing process and reduced the incidence of insufficient cementing strength defects.

  12. Research on a Defects Detection Method in the Ferrite Phase Shifter Cementing Process Based on a Multi-Sensor Prognostic and Health Management (PHM) System

    Science.gov (United States)

    Wan, Bo; Fu, Guicui; Li, Yanruoyue; Zhao, Youhu

    2016-01-01

    The cementing manufacturing process of ferrite phase shifters has the defect that cementing strength is insufficient and fractures always appear. A detection method of these defects was studied utilizing the multi-sensors Prognostic and Health Management (PHM) theory. Aiming at these process defects, the reasons that lead to defects are analyzed in this paper. In the meanwhile, the key process parameters were determined and Differential Scanning Calorimetry (DSC) tests during the cure process of resin cementing were carried out. At the same time, in order to get data on changing cementing strength, multiple-group cementing process tests of different key process parameters were designed and conducted. A relational model of cementing strength and cure temperature, time and pressure was established, by combining data of DSC and process tests as well as based on the Avrami formula. Through sensitivity analysis for three process parameters, the on-line detection decision criterion and the process parameters which have obvious impact on cementing strength were determined. A PHM system with multiple temperature and pressure sensors was established on this basis, and then, on-line detection, diagnosis and control for ferrite phase shifter cementing process defects were realized. It was verified by subsequent process that the on-line detection system improved the reliability of the ferrite phase shifter cementing process and reduced the incidence of insufficient cementing strength defects. PMID:27517935

  13. The Use of Micro and Nano Particulate Fillers to Modify the Mechanical and Material Properties of Acrylic Bone Cement

    Science.gov (United States)

    Slane, Joshua A.

    Acrylic bone cement (polymethyl methacrylate) is widely used in total joint replacements to provide long-term fixation of implants. In essence, bone cement acts as a grout by filling in the voids left between the implant and the patient's bone, forming a mechanical interlock. While bone cement is considered the `gold standard' for implant fixation, issues such as mechanical failure of the cement mantle (aseptic loosening) and the development of prosthetic joint infection (PJI) still plague joint replacement procedures and often necessitate revision arthroplasty. In an effort to address these failures, various modifications are commonly made to bone cement such as mechanical reinforcement with particles/fibers and the addition of antibiotics to mitigate PJI. Despite these attempts, issues such as poor particle interfacial adhesion, inadequate drug release, and the development of multidrug resistant bacteria limit the effectiveness of bone cement modifications. Therefore, the overall goal of this work was to use micro and nanoparticles to enhance the properties of acrylic bone cement, with particular emphasis placed on improving the mechanical properties, cumulative antibiotic release, and antimicrobial properties. An acrylic bone cement (Palacos R) was modified with three types of particles in various loading ratios: mesoporous silica nanoparticles (for mechanical reinforcement), xylitol microparticles (for increased antibiotic release), and silver nanoparticles (as an antimicrobial agent). These particles were used as sole modifications, not in tandem with one another. The resulting cement composites were characterized using a variety of mechanical (macro to nano, fatigue, fracture, and dynamic), imaging, chemical, thermal, biological, and antimicrobial testing techniques. The primary outcomes of this dissertation demonstrate that: (1) mesoporous silica, as used in this work, is a poor reinforcement phase for acrylic bone cement, (2) xylitol can significantly

  14. Compressive strength and frost heave resistance of different types of semi-rigid base materials after freeze-thaw cycles

    Institute of Scientific and Technical Information of China (English)

    ZhenYa Liu; JingYu Liu; QingZhi Wang; JianKun Liu

    2015-01-01

    Freeze-thaw damage is the most common disease of semi-rigid bases in cold regions, which may greatly affect the dura-bility of roadways. In this study, the compressive strength and frost resistance of four different types of semi-rigid bases (lime-fly ash-stabilized sand, cement-stabilized sand, lime-fly ash-stabilized gravel, and cement-stabilized gravel) are assessed by varying the materials content. Based on freeze-thaw and compressive strength tests, this paper presents the performance of the different materials, each having different physical properties, and the optimal amounts of materials contents are proposed.

  15. Corrosion-resistant Foamed Cements for Carbon Steels

    Energy Technology Data Exchange (ETDEWEB)

    Sugama T.; Gill, S.; Pyatina, T., Muraca, A.; Keese, R.; Khan, A.; Bour, D.

    2012-12-01

    The cementitious material consisting of Secar #80, Class F fly ash, and sodium silicate designed as an alternative thermal-shock resistant cement for the Enhanced Geothermal System (EGS) wells was treated with cocamidopropyl dimethylamine oxide-based compound as foaming agent (FA) to prepare numerous air bubble-dispersed low density cement slurries of and #61603;1.3 g/cm3. Then, the foamed slurry was modified with acrylic emulsion (AE) as corrosion inhibitor. We detailed the positive effects of the acrylic polymer (AP) in this emulsion on the five different properties of the foamed cement: 1) The hydrothermal stability of the AP in 200 and #61616;C-autoclaved cements; 2) the hydrolysis-hydration reactions of the slurry at 85 and #61616;C; 3) the composition of crystalline phases assembled and the microstructure developed in autoclaved cements; 4) the mechanical behaviors of the autoclaved cements; and, 5) the corrosion mitigation of carbon steel (CS) by the polymer. For the first property, the hydrothermal-catalyzed acid-base interactions between the AP and cement resulted in Ca-or Na-complexed carboxylate derivatives, which led to the improvement of thermal stability of the AP. This interaction also stimulated the cement hydration reactions, enhancing the total heat evolved during cement’s curing. Addition of AP did not alter any of the crystalline phase compositions responsible for the strength of the cement. Furthermore, the AP-modified cement developed the porous microstructure with numerous defect-free cavities of disconnected voids. These effects together contributed to the improvement of compressive-strength and –toughness of the cured cement. AP modification of the cement also offered an improved protection of CS against brine-caused corrosion. There were three major factors governing the corrosion protection: 1) Reducing the extents of infiltration and transportation of corrosive electrolytes through the cement layer deposited on the underlying CS

  16. Cementing Properties of Oil Shale Ash

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The oil crisis has prompted renewed interest in direct burning of oil shale as an alternative energy source.A major problem in this process is the large portion of ash produced.The cementing properties of this ash were investigated to determine its applicability as a building material.By means of XRD, IR, NMR and ICP, we have studied the effects of burning temperature on the reactivity of ash.Maximum reactivity was obtained with ash samples produced at 700 °C to 900 °C.In this range, the strength of oil-shale-based material, with properties similar to cement, which is composed of oil shale and several other kinds of solid wastes, can achieve the standard of 42.5# cement.Our study has provided an experimental foundation and theoretical base for a massive utilization of oil shale.

  17. Brushite-based calcium phosphate cement with multichannel hydroxyapatite granule loading for improved bone regeneration.

    Science.gov (United States)

    Sarkar, Swapan Kumar; Lee, Byung Yeol; Padalhin, Andrew Reyas; Sarker, Avik; Carpena, Nathaniel; Kim, Boram; Paul, Kallyanshish; Choi, Hwan Jun; Bae, Sang-Ho; Lee, Byong Taek

    2016-01-01

    In this work, we report brushite-based calcium phosphate cement (CPC) system to enhance the in vivo biodegradation and tissue in-growth by incorporation of micro-channeled hydroxyapatite (HAp) granule and silicon and sodium addition in calcium phosphate precursor powder. Sodium- and silicon-rich calcium phosphate powder with predominantly tri calcium phosphate (TCP) phase was synthesized by an inexpensive wet chemical route to react with mono calcium phosphate monohydrate (MCPM) for making the CPC. TCP nanopowder also served as a packing filler and moderator of the reaction kinetics of the setting mechanism. Strong sintered cylindrical HAp granules were prepared by fibrous monolithic (FM) process, which is 800 µm in diameter and have seven micro-channels. Acid sodium pyrophosphate and sodium citrate solution was used as the liquid component which acted as a homogenizer and setting time retarder. The granules accelerated the degradation of the brushite cement matrix as well as improved the bone tissue in-growth by permitting an easy access to the interior of the CPC through the micro-channels. The addition of micro-channeled granule in the CPC introduced porosity without sacrificing much of its compressive strength. In vivo investigation by creating a critical size defect in the femur head of a rabbit model for 1 and 2 months showed excellent bone in-growth through the micro-channels. The granules enhanced the implant degradation behavior and bone regeneration in the implanted area was significantly improved after two months of implantation.

  18. Working group report on simulation and in-situ observation of cement paste fluidity

    OpenAIRE

    Asakura, Etsuro; Tanaka, Hisanobu; Shimosaka, Kenichi; Tsukamoto, Katsuo; Komatsu, Ryuichi; Yoshizaki, Izumi; 朝倉 悦郎; 田中 久順; 下坂 建一; 塚本 勝男; 小松 隆一; 吉崎 泉

    2007-01-01

    We are studying the use of cement on the moon as a building material and the control of its properties, especially fluidity. The viscosity of cement paste in the space may be predicted by the general viscosity equation of Hattori and Izumi based on the DLVO (Derjaguin, Landau, Verway, Overbeek) theory that requires some parameters such as the particle friction coefficient, etc. In situ observation of dispersed particles in cement paste will be a key technology to clarify the mechanisms of the...

  19. The Effect Of Pozzolan Surface Properties On Physical And Mechanical Properties Of Cement Mortars

    OpenAIRE

    KOÇAK, YILMAZ; DORUM, Atila; Bülent YILMAZ; UCAR, Ali

    2010-01-01

    This study aims to determine mutual influence on blast furnace slag, fly ash and cement with added trass with Portland cement. For this purpose, physical, chemical, XRD, FT-IR, zeta (electrokinetic) potential and standard cement tests were applied to materials. In this study, it is shown that physical characteristics of pozzolan mostly depend on their molecular structures. Properties of molecular structure, in addition to its chrystal and amorphous character, change based on the existence of ...

  20. Development of a novel aluminum-free glass ionomer cement based on magnesium/strontium-silicate glasses.

    Science.gov (United States)

    Kim, Dong-Ae; Abo-Mosallam, Hany A; Lee, Hye-Young; Kim, Gyu-Ri; Kim, Hae-Won; Lee, Hae-Hyoung

    2014-09-01

    The effects of strontium substitution for magnesium in a novel aluminum-free multicomponent glass composition for glass ionomer cements (GICs) were investigated. A series of glass compositions were prepared based on SiO2-P2O5-CaO-ZnO-MgO(1-X)-SrOX-CaF2 (X=0, 0.25, 0.5 and 0.75). The mechanical properties of GICs prepared were characterized by compressive strength, flexural strength, flexural modules, and microhardness. Cell proliferation was evaluated indirectly by CCK-8 assay using various dilutions of the cement and rat mesenchyme stem cells. Incorporation of strontium instead of magnesium in the glasses has a significant influence on setting time of the cements and the properties. All mechanical properties of the GICs with SrO substitution at X=0.25 were significantly increased, then gradually decreased with further increase of the amount of strontium substitution in the glass. The GIC at X=0.25, also, showed an improved cell viability at low doses of the cement extracts in comparison with other groups or control without extracts. The results of this study demonstrate that the glass compositions with strontium substitution at low levels can be successfully used to prepare aluminum-free glass ionomer cements for repair and regeneration of hard tissues.

  1. Characterization of a calcium phosphate cement based on alpha-tricalcium phosphate obtained by wet precipitation process

    Energy Technology Data Exchange (ETDEWEB)

    Thurmer, M.B.; Diehl, C.E.; Vieira, R.S.; Coelho, W.T.G.; Santos, L.A., E-mail: monicathurmer@yahoo.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Dept. de Engenharia de Materiais

    2012-07-01

    There are several systems of calcium phosphate cements being studied. Those based on alpha-tricalcium phosphate are of particular interest. After setting they produce calcium deficient hydroxyapatite similar to bone like hydroxyapatite. This work aims to obtain alpha-tricalcium phosphate powders by the wet precipitation process, using calcium nitrate and phosphoric acid as reagents. This powder was characterized by infrared spectroscopy, X-ray diffraction and particle size distribution. In order to prepare the calcium phosphate cement, the powder was mixed with an accelerator in an aqueous solution. The mechanical properties of the cement were assessed and it was evaluated by means of apparent density, X-ray diffraction and scanning electron microscopy. The described method produced crystalline alpha-tricalcium phosphate as the major phase. The calcium phosphate cement showed high values of compression strength (50 MPa). The soaking of the cement in a simulated body fluid (SBF) formed a layer of hydroxyapatite like crystals in the surface of the samples. (author)

  2. Comparison of Biocompatibility of Cemented vs. Cementless Hip Joint Endoprostheses Based on Postoperative Evaluation of Proinflammatory Cytokine Levels

    Science.gov (United States)

    Szypuła, Jan; Cabak, Anna; Kiljański, Marek; Boguszewski, Dariusz; Tomaszewski, Wiesław

    2016-01-01

    Background The yearly increase in the number of procedures involving implantation of hip joint endoprostheses forces prosthetics manufacturers to search for biologically neutral implants. The goal of this study was to assess the concentration of Interleukin-6 (IL-6) and its correlation with C-reactive protein (CRP), depending on the type of hip joint endoprosthesis (cemented or cementless endoprosthesis) in order to determine implant biotolerance during the early postoperative period. Material/Methods The sample comprised 200 patients [mean age=64 (31–81) years] with coxarthrosis. All patients underwent hip joint arthroplasty using a cemented or cementless endoprosthesis. Blood samples were collected 3 times: before the procedure, on the first day after the procedure, and after 6 weeks. IL-6 and CRP levels were assayed using immunoenzymatic methods. The results were subjected to statistical analysis using the Shapiro-Wilk test. Results On the 1st day after the procedure, CRP and IL-6 concentration increased rapidly after implantation of both cemented and cementless endoprostheses. At 6 weeks postoperatively, the CRP value remained at a similar level in patients after cemented arthroplasty and was almost 2-fold lower in patients who underwent cementless arthroplasty. The IL-6 value returned to the baseline level in patients after cementless arthroplasty and showed an ongoing increasing tendency in patients after cemented arthroplasty. Conclusions 1. The measurement of C-reactive protein and Interleukin-6 is a high-sensitivity test, assessing implant biotolerance. 2. The implantation of a cemented endoprosthesis induces a higher increase in the level of proinflammatory cytokines as compared with a cementless endoprosthesis. 3. For a complete assessment of both early and later body responses to implantation and the related surgical procedure, further studies using available approaches and tools are recommended. PMID:27935873

  3. Cement and concrete

    Science.gov (United States)

    Corley, Gene; Haskin, Larry A.

    1992-01-01

    To produce lunar cement, high-temperature processing will be required. It may be possible to make calcium-rich silicate and aluminate for cement by solar heating of lunar pyroxene and feldspar, or chemical treatment may be required to enrich the calcium and aluminum in lunar soil. The effects of magnesium and ferrous iron present in the starting materials and products would need to be evaluated. So would the problems of grinding to produce cement, mixing, forming in vacuo and low gravity, and minimizing water loss.

  4. Influence of pore structure on compressive strength of cement mortar.

    Science.gov (United States)

    Zhao, Haitao; Xiao, Qi; Huang, Donghui; Zhang, Shiping

    2014-01-01

    This paper describes an experimental investigation into the pore structure of cement mortar using mercury porosimeter. Ordinary Portland cement, manufactured sand, and natural sand were used. The porosity of the manufactured sand mortar is higher than that of natural sand at the same mix proportion; on the contrary, the probable pore size and threshold radius of manufactured sand mortar are finer. Besides, the probable pore size and threshold radius increased with increasing water to cement ratio and sand to cement ratio. In addition, the existing models of pore size distribution of cement-based materials have been reviewed and compared with test results in this paper. Finally, the extended Bhattacharjee model was built to examine the relationship between compressive strength and pore structure.

  5. Preparation and Characterization of Injectable Brushite Filled-Poly (Methyl Methacrylate Bone Cement

    Directory of Open Access Journals (Sweden)

    Lucas C. Rodriguez

    2014-09-01

    Full Text Available Powder-liquid poly (methyl methacrylate (PMMA bone cements are widely utilized for augmentation of bone fractures and fixation of orthopedic implants. These cements typically have an abundance of beneficial qualities, however their lack of bioactivity allows for continued development. To enhance osseointegration and bioactivity, calcium phosphate cements prepared with hydroxyapatite, brushite or tricalcium phosphates have been introduced with rather unsuccessful results due to increased cement viscosity, poor handling and reduced mechanical performance. This has limited the use of such cements in applications requiring delivery through small cannulas and in load bearing. The goal of this study is to design an alternative cement system that can better accommodate calcium-phosphate additives while preserving cement rheological properties and performance. In the present work, a number of brushite-filled two-solution bone cements were prepared and characterized by studying their complex viscosity-versus-test frequency, extrusion stress, clumping tendency during injection through a syringe, extent of fill of a machined void in cortical bone analog specimens, and compressive strength. The addition of brushite into the two-solution cement formulations investigated did not affect the pseudoplastic behavior and handling properties of the materials as demonstrated by rheological experiments. Extrusion stress was observed to vary with brushite concentration with values lower or in the range of control PMMA-based cements. The materials were observed to completely fill pre-formed voids in bone analog specimens. Cement compressive strength was observed to decrease with increasing concentration of fillers; however, the materials exhibited high enough strength for consideration in load bearing applications. The results indicated that partially substituting the PMMA phase of the two-solution cement with brushite at a 40% by mass concentration provided the best

  6. Correlation between microstructure, phase composition and mechanical properties of thermo-insulation bonding agents based on waste material

    Directory of Open Access Journals (Sweden)

    Terzić Anja

    2012-01-01

    Full Text Available Building composites - thermo-insulating and/or high-temperature resistant bonding agents in which fly ash, as potentially environmentally harmful waste material, is combined with ordinary and refractory cement is new option for reapplication of this waste material. In this study, investigated bonding agents were based on two types of fly ashes from coal combustion process and cements - ordinary Portland cement and highaluminate cement. Change of mineral phase composition of the composites with increasing temperature was analyzed by means of XRD method. Microstructural changes within investigated composites were investigated by means of scanning electron microscopy (SEM. Macro-performance - mechanical properties of the investigated bonding agents was finally correlated with its microstructure. The investigated bonding agents showed excellent compressive strength, while SEM and XRD analysis indicated its valuable refractory and thermo-insulation properties. [Projekat Ministarstva nauke Republike Srbije, br. 172057 i br. 45008

  7. Cement Formation

    DEFF Research Database (Denmark)

    Telschow, Samira; Jappe Frandsen, Flemming; Theisen, Kirsten

    2012-01-01

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

  8. Biomonitoring Study of Heavy Metals in Blood from a Cement Factory Based Community

    OpenAIRE

    Bank M.S.; Spengler J.D.

    2014-01-01

    Little is known about the effects of cement factory pollution, emissions, and kiln dust on contaminant exposure in human populations, including school environments, in close proximity to these point sources. In Ravena, New York, USA and vicinity, environmental pollution from a local cement plant is considered significant and substantial according to the United States Environmental Protection Agency’s Toxic Release Inventory, published in 2006, 2007, and 2010. We hypothesized that cement facto...

  9. The Materials and Energy Potential Method for the quantitative distincion between Valorization and Elimination in the Cement Industry

    NARCIS (Netherlands)

    Zeevalkink, J.A.; Alkemade, M.M.C.

    1996-01-01

    This report proposes a quantitative method to distinguish between valorization and elimination of waste in a cement kiln. Examples are calculated to illustrate the consequences of the developed approach. Valorization is defined as the processing of a waste in a cement kiln to substi-tute raw materia

  10. Pavement structure mechanics response of flexible on semi-flexible overlay that based on the old cement concrete pavement damage

    Directory of Open Access Journals (Sweden)

    Jiang Ruinan

    2015-01-01

    Full Text Available The old cement pavement damage status directly affect the design of the paving renovation. Based on the state of the old road investigation, combined with the research data at home and abroad, use the control index that average deflection, deflection value and CBR value to determine the reasonable time to overlay. Draw up the typical pavement structure according to the principle of combination of old cement pavement overlay structure design, and calculated that the tensile stress and shear stress in asphalt layer ,semi-flexible layer and the tensile in the old cement pavement adopting BISA3.0 statics finite element analysis model when modulus in the old road was diminishing. Use the computed result to analyses the influence of old road damage condition the influence of pavement structure.

  11. POZZOLAN AND CEMENTS WITH POZZOLAN

    Directory of Open Access Journals (Sweden)

    Hasan KAPLAN

    1995-02-01

    Full Text Available Cement, one of the basic material of construction engineering, has an important place in view of strength and cost of structures. Cement consumption is increasing parallel to development of building construction sector. For cement producers, minimal cost is desired by using new and economical material sources. On the other hand, the controllers and contractors need cheaper, safer and higher strength materials. From this respect cement industry tends to use cement with pozzolan. In Türkiye, cement with pozzolan is produced by adding the pozzolan, which has a large reservoir in the country, in cement in sertain amount. However this type of cement is consumed in the construction sector, sortage of scientific investigation and speculative news on the subject.are worried the users and producers. In this paper, prior to an experimental study on the cements having pozzolan additive, historical development of pozzolan, reservoir of Turkiye, and comparison with portland cement is carried out. Advantages and disadvantages of pozzolan are also discussed in some points.

  12. In Vitro Evaluation of Planktonic Growth on Experimental Cement-Retained Titanium Surfaces.

    Science.gov (United States)

    Balci, Nur; Cakan, Umut; Aksu, Burak; Akgul, Oncu; Ulger, Nurver

    2016-04-08

    BACKGROUND The purpose of this study was to compare the effects of selected cements, or their combination with titanium, on the growth of two periodontopathic bacteria: Prevotella intermedia (Pi) and Fusobacterium nucleatum (Fn). MATERIAL AND METHODS This study was comprised of several experimental groups: 1) Dental luting cements (glass ionomer cement, methacrylate-based resin cement, zinc-oxide eugenol cement, eugenol-free zinc oxide cement; 2) titanium discs; and 3) titanium combination cement discs. The disks were submerged in bacterial suspensions of either Fn or Pi. Planktonic bacterial growth within the test media was measured by determining the optical density of the cultures (OD600). Mean and standard deviations were calculated for planktonic growth from three separate experiments. RESULTS Intergroup comparison of all experimental groups revealed increased growth of Pi associated with cement-titanium specimens in comparison with cement specimens. Regarding the comparison of all groups for Fn, there was an increased amount of bacterial growth in cement-titanium specimens although the increase was not statistically significant. CONCLUSIONS The combination of cement with titanium may exacerbate the bacterial growth capacity of Pi and Fn in contrast to their sole effect.

  13. Lignin-Based Thermoplastic Materials.

    Science.gov (United States)

    Wang, Chao; Kelley, Stephen S; Venditti, Richard A

    2016-04-21

    Lignin-based thermoplastic materials have attracted increasing interest as sustainable, cost-effective, and biodegradable alternatives for petroleum-based thermoplastics. As an amorphous thermoplastic material, lignin has a relatively high glass-transition temperature and also undergoes radical-induced self-condensation at high temperatures, which limits its thermal processability. Additionally, lignin-based materials are usually brittle and exhibit poor mechanical properties. To improve the thermoplasticity and mechanical properties of technical lignin, polymers or plasticizers are usually integrated with lignin by blending or chemical modification. This Review attempts to cover the reported approaches towards the development of lignin-based thermoplastic materials on the basis of published information. Approaches reviewed include plasticization, blending with miscible polymers, and chemical modifications by esterification, etherification, polymer grafting, and copolymerization. Those lignin-based thermoplastic materials are expected to show applications as engineering plastics, polymeric foams, thermoplastic elastomers, and carbon-fiber precursors.

  14. Modelling and simulation of acrylic bone cement injection and curing within the framework of vertebroplasty

    CERN Document Server

    Landgraf, Ralf; Kolmeder, Sebastian; Lion, Alexander; Lebsack, Helena; Kober, Cornelia

    2013-01-01

    The minimal invasive procedure of vertebroplasty is a surgical technique to treat compression fractures of vertebral bodies. During the treatment liquid bone cement gets injected into the affected vertebral body and therein cures to a solid. In order to investigate the treatment and the impact of injected bone cement on the vertebra, an integrated modelling and simulation framework has been developed. The framework includes (i) the generation of computer models based on microCT images of human cancellous bone, (ii) CFD simulations of bone cement injection into the trabecular structure of a vertebral body as well as (iii) non-linear FEM simulations of the bone cement curing. Thereby, microstructural models of trabecular bone structures are employed. Furthermore, a detailed description of the material behaviour of acrylic bone cements is provided. More precisely, a non-linear fluid flow model is chosen for the representation of the bone cement behaviour during injection and a non-linear viscoelastic material mo...

  15. PRINCIPLES OF RE-ENGINEERING METHODOLOGY FOR TECHNOLOGICAL PROCESS IN PROCESSING OF RAW MATERIAL COMPONENTS WHILE PRODUCING CEMENT AND SILICATE PRODUCTS

    Directory of Open Access Journals (Sweden)

    I. A. Busel

    2014-01-01

    Full Text Available Grinding process is characterized by high energy consumption and low productivity. Nowadays efficiency of the ball mills applied for grinding is rather low. Only 3-6 % of the supplied power energy is used for material grinding. The rest part of the energy disappears in the form of heat, vibration and noise. So matter concerning reduction of energy consumption is of great importance.Improvement of efficiency and quality of technological process in grinding of raw material components while producing construction materials is considered as one of priority-oriented targets of power- and resource saving in construction industry with the purpose to reduce energy consumption for grinding. Grinding efficiency at operating enterprises is reasonable to improve by modernization of the equipment and existing technological, management and other processes which are related to grinding of mineral raw material. In order to reduce grinding power consumption it is necessary to carry out a complex re-engineering of technological process in grinding of various materials which is based on usage of new modifications of grinding bodies, physical and chemical grinding aids, modern information technologies and industrial automation equipment. Application of modern information technologies and industrial automation equipment makes it possible to execute the grinding process with maximum achievable productivity for existing capacity due to automatic control and consideration of continuous changes in technological parameters. In addition to this such approach gives an opportunity to control processes in real time by immediate adjustments of technological equipment operational modes.The paper considers an approach to the development of re-engineering methodology for technological process in grinding of raw material components while producing construction materials. The present state of technological grinding process is presented in the paper. The paper points out the

  16. Topological calculation of key parameters of fibre for production of foam concrete based on cement-free nanostructured binder

    Directory of Open Access Journals (Sweden)

    KHARKHARDIN Anatoly Nikolaevich

    2016-08-01

    Full Text Available Fiber reinforcement is the process of introduction of fibers of different origins into binding system to enhance strength, stress-strain behavior of products and structures. Maximal effect of reinforcing process is possible when optimal parameters (length and consumption of fibre are determined. Moreover one need to consider particle-size composition and hardening process of binding system. In this paper the critical length of natural and sinthesized fibres as well as minimally required content in cellular systems is calculated with the mathematical apparatus of structural topology. As an example the foam concrete based on cement-free nanostructured binder with basalt fibre and microreinforcing constructional polymeric fibre is studied. Fiber diameter, refined with microstructure analysis, accomplished by SEM-microscopy and experimentally determined packing density in loose and compact state are applied as input parameters. Measurement of the fibre topological characteristics with acceptable is accomplished according to material porosity and pore size. So the minimal effective fibre length taking into account homogeneous distribution in bulk of composite matrix is less of 1 mm; minimal fibre consumption is 0,2–0,5 (by wt. %. Irrational optimization leads to unreasonable cost growth of final materials as well as formation of balling inclusions that negatively affects on final performance of composite.

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

    Directory of Open Access Journals (Sweden)

    F. Sasani

    2004-09-01

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

  18. EVALUATION OF CHEMICALS INCORPORATED WOOD FIBRE CEMENT MATRIX PROPERTIES

    Directory of Open Access Journals (Sweden)

    MST. SADIA MAHZABIN

    2013-08-01

    Full Text Available Wood fibre cement (WFC boards are well established commercially and widely used in many developed countries. The combination of the properties of two important materials, i.e., cement, and previously treated fibrous materials like wood or agricultural residues; which made up the board, contributed in the performance of the board as building material. In this work, the WFC matrix (WFCM samples are produced to determine the physical properties of WFCM such as the density and water absorption. The wood fibres are incorporated/treated with three different chemical additives; calcium formate (Ca(HCOO2, sodium silicate (Na2.SiO3 and magnesium chloride (MgCl2 prior to mixing with cement. The mechanical properties of the WFCM, with or without chemicals treatment of fibres, such as the compressive strength and flexural strength are evaluated. Three wood/cement ratios (50:50, 40:60, 30:70 are used and the percentages of water and accelerator were 80% and 3% based on the cement weight, respectively. Three moisture-conditioned samples; accelerated aging, dry and wet conditions are used for flexural test. The results reveal that the wood/cement ratio, chemical additives and moisture content had a marked influence on the physical and mechanical properties of the matrix. Finally, it has been shown that the 40:60 wood/cement ratio samples with prior chemicals treatment of the fibres that undergo accelerated aging conditioning achieve higher strength then dry and wet-conditioned boards.

  19. Mechanism of Functional Responses to Loading of Carbon Fiber Reinforced Cement-based Composites

    Institute of Scientific and Technical Information of China (English)

    JIANG Cuixiang; LI Zhuoqiu; SONG Xianhui; LU Yong

    2008-01-01

    Single fiber pull-out testing was conducted to study the origin of the functional responses to loading of carbon fiber reinforced cement-based composites.The variation of electrical resistance with the bonding force on the fiber-matrix interface was measured.Single fiber electromechanical testing was also conducted by measuring the electrical resistance under static tension.Comparison of the results shows that the resistance increasing during single fiber pull-out is mainly due to the changes at the interface.The conduction mechanism of the composite can be explained by the tunneling model.The interfacial stress causes the deformation of interfacial structure and the interfacial debonding.which have influences on the tunneling effect and result in the change of resistance.

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

    Directory of Open Access Journals (Sweden)

    Huimei ZHU

    2014-09-01

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

  1. The effect of different surfactants/plastisizers on the electrical behavior of CNT nano-modified cement mortars

    Science.gov (United States)

    Dalla, P. T.; Alafogianni, P.; Tragazikis, I. K.; Exarchos, D. A.; Dassios, K.; Barkoula, N.-M.; Matikas, T. E.

    2015-03-01

    Cement-based materials have in general low electrical conductivity. Electrical conductivity is the measure of the ability of the material to resist the passage of electrical current. The addition of a conductive admixture such as Multi-Walled Carbon Nanotubes (MWCNTs) in a cement-based material increases the conductivity of the structure. This research aims to characterize nano-modified cement mortars with MWCNT reinforcements. Such nano-composites would possess smartness and multi-functionality. Multifunctional properties include electrical, thermal and piezo-electric characteristics. One of these properties, the electrical conductivity, was measured using a custom made apparatus that allows application of known D.C. voltage on the nano-composite. In this study, the influence of different surfactants/plasticizers on CNT nano-modified cement mortar specimens with various concentrations of CNTs (0.2% wt. cement CNTs - 0.8% wt. cement CNTs) on the electrical conductivity is assessed.

  2. Si-based thin film coating on Y-TZP: Influence of deposition parameters on adhesion of resin cement

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, José Renato Cavalcanti, E-mail: joserenatocq@hotmail.com [Potiguar University, Department of Biotechnology, Natal (Brazil); Nogueira Junior, Lafayette [São Paulo State University, Department of Prosthodontics and Dental Materials, São José dos Campos (Brazil); Massi, Marcos [Federal University of São Paulo, Institute of Science and Technology, São José dos Campos (Brazil); Silva, Alecssandro de Moura; Bottino, Marco Antonio [São Paulo State University, Department of Prosthodontics and Dental Materials, São José dos Campos (Brazil); Sobrinho, Argemiro Soares da Silva [Technological Institute of Aeronautics, Department of Physics, São José dos Campos (Brazil); Özcan, Mutlu [University of Zurich, Dental Materials Unit, Center for Dental and Oral Medicine, Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Zurich (Switzerland)

    2013-10-01

    This study evaluated the influence of deposition parameters for Si-based thin films using magnetron sputtering for coating zirconia and subsequent adhesion of resin cement. Zirconia ceramic blocks were randomly divided into 8 groups and specimens were either ground finished and polished or conditioned using air-abrasion with alumina particles coated with silica. In the remaining groups, the polished specimens were coated with Si-based film coating with argon/oxygen magnetron discharge at 8:1 or 20:1 flux. In one group, Si-based film coating was performed on air-abraded surfaces. After application of bonding agent, resin cement was bonded. Profilometry, goniometry, Energy Dispersive X-ray Spectroscopy and Rutherford Backscattering Spectroscopy analysis were performed on the conditioned zirconia surfaces. Adhesion of resin cement to zirconia was tested using shear bond test and debonded surfaces were examined using Scanning Electron Microscopy. Si-based film coating applied on air-abraded rough zirconia surfaces increased the adhesion of the resin cement (22.78 ± 5.2 MPa) compared to those of other methods (0–14.62 MPa) (p = 0.05). Mixed type of failures were more frequent in Si film coated groups on either polished or air-abraded groups. Si-based thin films increased wettability compared to the control group but did not change the roughness, considering the parameters evaluated. Deposition parameters of Si-based thin film and after application of air-abrasion influenced the initial adhesion of resin cement to zirconia.

  3. Biocompatibility of alendronate-loaded acrylic cement for vertebroplasty

    Directory of Open Access Journals (Sweden)

    T Calvo-Fernández

    2010-10-01

    Full Text Available This paper reports a biological evaluation of a non-resorbable acrylic cement loaded with alendronate for the treatment of osteoporotic vertebral compression fractures. The cement formulation was based on polymethyl methacrylate and acrylic monomers; one of these had covalently linked vitamin E residues. The same cement in the absence of alendronate was used as a control. The setting of the charged cement presented a maximum polymerization temperature of 44ºC, a setting time of 24 min, a residual monomer content lower than 3 wt.%, a compressive strength of 99±10 MPa and an elastic modulus of 1.2±0.2 GPa. Cytotoxicity studies using human osteoblast cultures revealed that the leachable substances of the alendronate loaded cement collected between 1 and 7 days decreased cell viability to values lower than 80%. However, morphological changes and cellular damage in cells produced by the extracts decreased with the leak time. Cell adhesion and growth on charged cement was significantly lower than on the control. Implantation of the cement paste in the intra-femoral cavity of rabbits showed that initially the osteogenic activity was evident for the cement charged with alendronate, and the osteosynthesis process took place mainly in the trabeculae and was manifested by the presence of a non-mineralised osseous spicule. The interface between material and adjacent bone tissue was initially characterized by a variable fibrous response that in many cases it appeared reduced to thin connective tissue after a 24-week-period.

  4. Acoustic response of cemented granular sedimentary rocks: molecular dynamics modeling.

    Science.gov (United States)

    García, Xavier; Medina, Ernesto

    2007-06-01

    The effect of cementation processes on the acoustical properties of sands is studied via molecular dynamics simulation methods. We propose numerical methods where the initial uncemented sand is built by simulating the settling process of sediments. Uncemented samples of different porosity are considered by emulating natural mechanical compaction of sediments due to overburden. Cementation is considered through a particle-based model that captures the underlying physics behind the process. In our simulations, we consider samples with different degrees of compaction and cementing materials with distinct elastic properties. The microstructure of cemented sands is taken into account while adding cement at specific locations within the pores, such as grain-to-grain contacts. Results show that the acoustical properties of cemented sands are strongly dependent on the amount of cement, its stiffness relative to the hosting medium, and its location within the pores. Simulation results are in good correspondence with available experimental data and compare favorably with some theoretical predictions for the sound velocity within a range of cement saturation, porosity, and confining pressure.

  5. Analysis of Cement-Based Pastes Mixed with Waste Tire Rubber

    Science.gov (United States)

    Sola, O. C.; Ozyazgan, C.; Sayin, B.

    2017-03-01

    Using the methods of thermal gravimetry, differential thermal analysis, Furier transform infrared analysis, and capillary absorption, the properties of a cement composite produced by introducing waste tyre rubber into a cement mixture were investigated. It was found that the composite filled with the rubber had a much lower water absorption ability than the unfilled one.

  6. Cytotoxic effects of new MTA-based cement formulations on fibroblast-like MDPL-20 cells.

    Science.gov (United States)

    Garcia, Lucas da Fonseca Roberti; Santos, Alailson Domingos dos; Moraes, João Carlos Silos; Costa, Carlos Alberto de Souza

    2016-01-01

    The present study aimed at evaluating the cytotoxic effects of a novel cement called CER on periodontal fibroblast-like cells of mice (MDPL-20), in comparison with different formulations of Mineral Trioxide Aggregate (MTA), by means of the cell viability test (MTT) and cell morphology analysis. Thirty-two round-shaped samples were fabricated with the following cements: white MTA, white and gray CER and experimental white MTA. The samples were immersed in serum-free culture medium for 24 hours or 7 days (n = 16). The extracts (culture medium + components released from the cements) were applied for 24 hours to previously cultured cells (40.000 cells/cm2) in the wells of 24-well plates. Cells seeded in complete culture medium were used as a negative control. Cell viability was assessed using the MTT assay. Two samples of each cement were used for cell morphology analysis by Scanning Electron Microscopy (SEM). The extracts obtained at the 7-day period presented higher cytotoxicity compared with the 24-hour period (p MTA presented the lowest, similar to the control (p > 0.05). However, at the 7-day period, the experimental white MTA presented no significant difference in comparison with the other cements (p > 0.05). At the 7-day period, CER cement presented cytotoxic effects on fibroblast-like cells, similar to different MTA formulations. However, the immersion period in the culture medium influenced the cytotoxicity of the cements, which was greater for CER cement at 24 hours.

  7. Pore Structure of Cement Pastes Blended with Volcanic Rock

    Institute of Scientific and Technical Information of China (English)

    YU Lehua; ZHOU Shuangxi; LI Liling

    2016-01-01

    The pore parameters of cement pastes blended with volcanic rock at the curing age of 1, 28 and 90 d were de-termined by a mercury intrusion porosimetry. The pore structure of the pastes was characterized through the analysis of porosity, average pore diameter, the most probable pore aperture, pore size distribution, as well as total pore volume. For the improvement of mechanical property and durability of cement-based material, the correlation of the formed pore structure with hydration time and replacement level of volcanic rock for cement was revealed. The results indicate that volcanic rock can diminish porosity and reduce pore size in cement paste when curing time prolongs, which is particu-larly prominent with replacement level of less than 20% in late period. The more harmful pores (i.e., capillary pore) are gradually transformed into harmless pore (i.e., gel pores or micropore), even fully filled and disappeared when hydration products increase. The pore structure of the cement paste is thus refined. The beneficial effect of volcanic rock on the pore structure of cement paste could enhance the mechanical property and durability of cement-based material.

  8. Effect of metakaolin on strength and efflorescence quantity of cement-based composites.

    Science.gov (United States)

    Weng, Tsai-Lung; Lin, Wei-Ting; Cheng, An

    2013-01-01

    This study investigated the basic mechanical and microscopic properties of cement produced with metakaolin and quantified the production of residual white efflorescence. Cement mortar was produced at various replacement ratios of metakaolin (0, 5, 10, 15, 20, and 25% by weight of cement) and exposed to various environments. Compressive strength and efflorescence quantify (using Matrix Laboratory image analysis and the curettage method), scanning electron microscopy, and X-ray diffraction analysis were reported in this study. Specimens with metakaolin as a replacement for Portland cement present higher compressive strength and greater resistance to efflorescence; however, the addition of more than 20% metakaolin has a detrimental effect on strength and efflorescence. This may be explained by the microstructure and hydration products. The quantity of efflorescence determined using MATLAB image analysis is close to the result obtained using the curettage method. The results demonstrate the best effectiveness of replacing Portland cement with metakaolin at a 15% replacement ratio by weight.

  9. Effect of Lime on Mechanical and Durability Properties of Blended Cement Based Concrete

    Science.gov (United States)

    Acharya, Prasanna Kumar; Patro, Sanjaya Kumar; Moharana, Narayana C.

    2016-06-01

    This work presents the results of experimental investigations performed to evaluate the effect of lime on mechanical and durability properties of concrete mixtures made with blended cement like Portland Slag Cement (PSC) and Portland Pozzolana Cement (PPC) with lime content of 0, 5, 7 and 10 %. Test result indicated that inclusion of hydraulic lime on replacement of cement up to 7 % increases compressive strength of concrete made with both PSC and PPC. Flexural strength increased with lime content. Highest flexural strength is reported at 7 % lime content for both PSC and PPC. Workability is observed to decrease with lime addition which could be compensated with introduction of super plasticizer. Acid and sulphate resistance increase slightly up to 7 % of lime addition and is found to decrease with further addition of lime. Lime addition up to 10 % does not affect the soundness of blended cements like PSC and PPC.

  10. Setting mechanisms of an acidic premixed calcium phosphate cement

    OpenAIRE

    2013-01-01

    Premixed calcium phosphate cements (pCPC), where glycerol is used instead of water as mixing liquid, present better handling characteristics than water-based cements. However, the setting mechanisms of pCPC have not been described thoroughly. The aim of this paper is to increase the understanding of the setting mechanism of pCPC. The investigated cement starts to set when glycerol is exchanged with water via diffusion of glycerol out to the surrounding body fluid and water into the material. ...

  11. Early age monitoring of cement mortar using embedded piezoelectric sensors

    Science.gov (United States)

    Narayanan, Arun; Subramaniam, Kolluru V. L.

    2016-04-01

    A piezoceramic based sensor consisting of embedded Lead Zirconate Titanate (PZT) patch is developed for assessing the progression of hydration and evolution of properties of cement mortar. A method for continuous assessment of cement mortar with different water to cement ratios after casting is presented. The method relies on monitoring changes in the electromechanical (EM) conductance of a PZT patch embedded in mortar. Changes in conductance are shown to sensitively reflect the changes in the mechanical impedance of the cementitious material as it transforms from fluid to solid state.

  12. Global warming impact on the cement and aggregates industries

    Energy Technology Data Exchange (ETDEWEB)

    Davidovits, J. (Cordi-Geopolymere SA, Saint-Quentin (France). Geopolymer Inst.)

    1994-06-01

    CO[sub 2] related energy taxes are focusing essentially on fuel consumption, not on actual CO[sub 2] emission measured at the chimneys. Ordinary Portland cement, used in the aggregates and industries, results from the calcination of limestone and silica. The production of 1 ton of cement directly generates 0.55 tons of chemical-CO[sub 2] and requires the combustion of carbon-fuel to yield an additional 0.40 tons of CO[sub 2]. The 1987 1 billion metric tons world production of cement accounted for 1 billion metric tons of CO[sub 2], i.e., 5% of the 1987 world CO[sub 2] emission. A world-wide freeze of CO[sub 2] emission at the 1990 level as recommended by international institutions, is incompatible with the extremely high cement development needs of less industrialized countries. Present cement production growth ranges from 5% to 16% and suggests that in 25 years from now, world cement CO[sub 2] emissions could equal 3,500 million tons. Eco-taxes when applied would have a spectacular impact on traditional Portland cement based aggregates industries. Taxation based only on fuel consumption would lead to a cement price increase of 20%, whereas taxation based on actual CO[sub 2] emission would multiply cement price by 1.5 to 2. A 25--30% minor reduction of CO[sub 2] emissions may be achieved through the blending of Portland cement with replacement materials such as coal-fly ash and iron blast furnace slag.

  13. Polyphosphazine-based polymer materials

    Science.gov (United States)

    Fox, Robert V.; Avci, Recep; Groenewold, Gary S.

    2010-05-25

    Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-02-01

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

  15. Use of Fluidized Bed Combustion Ash and Other Industrial Wastes as Raw Materials for the Manufacture of Calcium Sulphoaluminate Cements

    Science.gov (United States)

    Marroccoli, M.; Montagnaro, F.; Pace, M. L.; Telesca, A.; Valenti, G. L.

    Calcium sulphoaluminate cements, mainly composed by 4CaO·3Al2O3·SO3 and 2CaO·SiO2, are special hydraulic binders which require limestone, bauxite and gypsum as natural raw materials for their manufacture. In order to save bauxite and natural gypsum, it has been explored the possibility of using, among the raw mix components, FBC waste together with pulverised coal fly ash or anodization mud and, when necessary, flue gas desulphurization gypsum. Mixtures containing limestone (29-39%), FBC waste (30-44%), pulverised coal fly ash (0-13%) or anodization mud (0-32%), bauxite (0-18%) and flue gas desulphurization gypsum (0-8%) were heated for 2 hours in a laboratory electric oven at temperatures ranging from 1150° to 1300°C. The X-ray diffraction patterns on the burnt products generally showed a good conversion of the reactants and a high selectivity degree towards 4CaO·3Al2O3·SO3, particularly at 1250°C.

  16. Usage of soil-cement for levee protection

    OpenAIRE

    2016-01-01

    In this thesis a comparison between various designs of embankments using soil-cement was made. In the first section history and usage history is described, based on a literature overview. Materials, properties and construction technologies are also desribed. In the second section seepage control is conducted using Feflow and GeoStudio Seep software. The analysis was made on an embankment with upstream soilcement protection and on an embankment with soil-cement central core. From the results o...

  17. Propriedades e bioatividade de um cimento endodôntico à base de aluminato de cálcio Properties and bioactivity of endodontic calcium aluminate cement

    Directory of Open Access Journals (Sweden)

    I. R. Oliveira

    2011-09-01

    Full Text Available Desde sua introdução na endodontia como um material retro-obturador e selador de defeitos da raiz dental, o agregado de trióxido mineral (MTA tem sido considerado como um material endodôntico revolucionário. Apesar disso, este material apresenta algumas propriedades limitantes, necessitando alterações em sua composição bem como desenvolvimento de novos materiais. Assim, o objetivo desse trabalho foi mostrar a influência de aditivos no desenvolvimento de um cimento endodôntico à base de cimento de aluminato de cálcio (ECAC. Além disso, foram avaliadas as propriedades do ECAC em comparação com o MTA, quando em contato com solução de fluido corporal simulado (SBF. Testes de manipulação e medidas de resistência à compressão, porosidade aparente, tempo de endurecimento, pH e condutividade iônica, foram realizados para os materiais MTA puro e ECAC contendo aditivos. Considerando as propriedades apresentadas pelo ECAC, este material alternativo pode ser indicado para múltiplas aplicações em endodontia.The mineral trioxide aggregate (MTA, a material primarily developed as a root-end filling has been extensively investigated as an innovative product for endodontic applications. However, changes in its formulation/composition involving its mineral aggregates and the development of alternatives of materials have been proposed in an attempt to overcome its negative physical-chemical characteristics. In this work, the influence of additives addition on the development of a novel endodontic cement based on calcium aluminate, has been evaluated. In addition, the properties of endodontic calcium aluminate cement (ECAC were compared with the gold standard mineral-trioxide-aggregate in contact with simulated body fluid (SBF. Manipulation tests and measurements of compressive strength, apparent porosity, setting time, pH and ionic conductivity were carried out on plain MTA and calcium aluminate cement with and without various additives

  18. Influence of supplementary cementitious materials on water transport kinetics and mechanical properties of hydrated lime and cement mortars

    Directory of Open Access Journals (Sweden)

    Ince, C.

    2015-06-01

    Full Text Available The purpose of this paper is an investigation of the possible role of supplementary cementitious materials (SCMs on water transport kinetics and mechanical properties of hydrated lime (CL90 and Portland cement (PC mortars. The properties of hydrated lime are significantly different from those of cement and therefore modifying fresh and hardened properties of these mortars are vital for mortar/substrate optimisation in masonry construction. The parameters investigated in this paper often are the main barriers to the use of hydrated lime in construction practice. The results show that transfer sorptivity and time to dewater freshly-mixed hydrated lime mortars can be modified when binder is partially replaced with SCMs. Compressive strength of CL90 mortars is increased systematically with the increased replacement levels of SCMs and the results are supported with the microstructural images. The ability to modify the water transport kinetics and mechanical properties allows compatibility between the mortar and the substrate unit in masonry construction.El objetivo de este artículo es investigar el papel de los materiales cementantes suplementarios (SCMs en la cinética de transporte del agua y en las propiedades mecánicas de los morteros de cal hidratada (CL90 y cemento Portland. Las propiedades de la cal hidratada son significativamente diferentes a las del cemento y por lo tanto el control de las propiedades de los morteros frescos y endurecidos es fundamental en la optimización mortero/substrato en albañilería. Los parámetros estudiados en este trabajo son a menudo las principales barreras para el uso de la cal hidratada en la práctica de la construcción. Los resultados indican que la absortividad y el tiempo necesario para deshidratar morteros de cal hidratada recién mezclados pueden ser controlados cuando el conglomerante es parcialmente remplazado por SCMs. La resistencia a compresión de los morteros CL90 aumenta sistem

  19. Accelerated carbonation testing of mortar with supplementary cement materials. Limitation of the acceleration due to drying

    NARCIS (Netherlands)

    Visser, J.H.M.

    2012-01-01

    In the design stage of a concrete structure, decisions have to be made on how to fulfil the required service life and consequently, what concrete composition to use. Concrete compositions can be chosen on account of known performances but this will limit the choice of compositions and materials to t

  20. Lithological and land-use based assessment of heavy metal pollution in soils surrounding a cement plant in SW Europe.

    Science.gov (United States)

    Cutillas-Barreiro, Laura; Pérez-Rodríguez, Paula; Gómez-Armesto, Antía; Fernández-Sanjurjo, María José; Álvarez-Rodríguez, Esperanza; Núñez-Delgado, Avelino; Arias-Estévez, Manuel; Nóvoa-Muñoz, Juan Carlos

    2016-08-15

    We study the influence of phasing out a cement plant on the heavy metal (Hg, Pb and Cr) content in the surrounding soils, taking into account factors often neglected, such as contributions due to local lithology or land use. The range of total Hg was 10-144µg kg(-1), reaching up to 41 and 145mgkg(-1) for total contents of Pb and Cr, respectively. Forest soils showed higher concentration of Hg than prairie soils, indicating the importance of land use on the accumulation of volatile heavy metals in soils. In forest soils, total Hg showed a trend to decrease with soil depth, whereas in prairie soils the vertical pattern of heavy metal concentrations was quite homogeneous. In most cases, the distance to the cement plant was not a factor of influence in the soils content of the analyzed heavy metals. Total Pb and Cr contents in soils nearby the cement plant were quite similar to those found in the local lithology, resulting in enrichment factor values (EF's) below 2. This suggests that soil parent material is the main source of these heavy metals in the studied soils, while the contribution of the cement plant to Pb and Cr soil pollution was almost negligible. On the contrary, the soils surrounding the cement plant accumulate a significant amount of Hg, compared to the underlying lithology. This was especially noticeable in forest soils, where Hg EF achieved values up to 36. These results are of relevance, bearing in mind that Hg accumulation in soils may be an issue of environmental concern, particularly in prairie soils, where temporal flooding can favor Hg transformation to highly toxic methyl-Hg. In addition, the concurrence of acid soils and total-Cr concentrations in the range of those considered phytotoxic should be also stressed.

  1. Study on the hydration activity of ground dolomite in cementing material%白云石粉在水泥基材料中的水化活性研究

    Institute of Scientific and Technical Information of China (English)

    肖佳; 吴婷; 郭明磊

    2016-01-01

    研究了白云石粉在水泥基材料中的水化活性,分析了白云石粉掺量和细度的影响。研究表明,白云石粉掺量为0~30%时,白云石粉在水泥基材料中的强度贡献率大于零,提高了水泥基材料的比强度;随白云石粉掺量增加,水泥-白云石粉胶凝体系的强度及白云石粉在水泥基材料中的活性指数先增大后减小,白云石粉掺量为5%时均达到峰值。随白云石粉细度增大,水泥-白云石粉胶凝体系强度和比强度及白云石粉在水泥基材料中强度贡献率及活性指数均先增大后减小。白云石粉在水泥基材料中发生了去白云石化反应,阻止钙矾石向单硫型水化硫铝酸钙转化,并反应生成了水化碳铝酸钙(C3A·CaCO3·11H2O)。%The hydration activity of ground dolomite in cement based materials was studied,and the influence of the content and fine-ness of ground dolomite were analyzed.The results show that,when the ground dolomite content is 0~30%, the strength contribution rate of ground dolomite was greater than zero and the ground dolomite improved the specific strength of the cementing materi