WorldWideScience

Sample records for cementing materials modelisation

  1. 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.

  2. 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

  3. Performance of Cement Containing Laterite as Supplementary Cementing Material

    Directory of Open Access Journals (Sweden)

    Abbas Bukhari, Z. S.

    2013-03-01

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

  4. Contribution to the modeling of elaborate cement barriers behaviour with respect to radioelements migration by the study of ancient analogue materials; Apport de l`etude de materiaux analogues anciens a la modelisation du comportement des barrieres ouvragees en ciment vis-a-vis de la migration des radioelements

    Energy Technology Data Exchange (ETDEWEB)

    Rougeau, P.

    1994-10-13

    The durability of cement matrices and their capacity of radioelements retention are determining factors for their use as elaborate barriers in radioactive waste disposal facilities. This study focusses on the observation of concretes in real situation of alteration or in contact with radioelements for predictive modelling. Two materials have been selected. One is a concrete from a gallery wall of the Margnac uranium mine (Cogema, France) submitted to uranium-rich infiltration waters. The alteration concentrates in two characteristic successive zones: the first is composed of calcium depleted and aluminum enriched calcite and calcium hydro-silicates and the second, between the first zone and the sound matrix, is characterized by a self-filling in process due to massive ettringite precipitation induced by sulfate ions transport. Uranium migration depends closely on the fissures and porosity of the cement matrix. The second series of samples correspond to 2000 years old archaeological cements from Pompei (Italy) made of volcanic ashes and carrying uranium traces. These samples were submitted to burying and alteration is characterized by a carbonation of the cement matrix. The mineralogy is closed to the one defined in the first alteration zone of the uranium mine concrete. Both studies demonstrate that the presence of carbonate ions in the percolation water plays a major role in the alteration process. Sulfate reactions must be considered too and tend to diminish the materials porosity and to increase the delay in radionuclides migration processes. (J.S.). 131 refs., 92 figs., 55 tabs., 51 photos., 15 appends.

  5. Cement replacement materials. Properties, durability, sustainability

    Energy Technology Data Exchange (ETDEWEB)

    Ramezanianpour, Ali Akbar [Amirkabir Univ. of Technology, Tehran (Iran, Islamic Republic of). Concrete Technology Center

    2014-04-01

    The aim of this book is to present the latest findings in the properties and application of Supplementary Cementing Materials and blended cements currently used in the world in concrete. Sustainability is an important issue all over the world. Carbon dioxide emission has been a serious problem in the world due to the greenhouse effect. Today many countries agreed to reduce the emission of CO2. Many phases of cement and concrete technology can affect sustainability. Cement and concrete industry is responsible for the production of 7% carbon dioxide of the total world CO2 emission. The use of supplementary cementing materials (SCM), design of concrete mixtures with optimum content of cement and enhancement of concrete durability are the main issues towards sustainability in concrete industry.

  6. A novel cement-based hybrid material

    International Nuclear Information System (INIS)

    Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) are known to possess exceptional tensile strength, elastic modulus and electrical and thermal conductivity. They are promising candidates for the next-generation high-performance structural and multi-functional composite materials. However, one of the largest obstacles to creating strong, electrically or thermally conductive CNT/CNF composites is the difficulty of getting a good dispersion of the carbon nanomaterials in a matrix. Typically, time-consuming steps of purification and functionalization of the carbon nanomaterial are required. We propose a new approach to grow CNTs/CNFs directly on the surface of matrix particles. As the matrix we selected cement, the most important construction material. We synthesized in a simple one-step process a novel cement hybrid material (CHM), wherein CNTs and CNFs are attached to the cement particles. The CHM has been proven to increase 2 times the compressive strength and 40 times the electrical conductivity of the hardened paste, i.e. concrete without sand.

  7. A consistent thermodynamic database for cement materials

    International Nuclear Information System (INIS)

    In the context of waste confinement and, more specifically, waste from the nuclear industry, concrete is used both as a confinement and as a building material. Alteration processes in contact with clayey formations are also of interest in the context of deep disposal. The present work aims to propose a collection of thermodynamic properties for geochemical calculation in cementitious media. This selection is extended to zeolites and clay minerals in the context of cement/clay interactions. Finally, because temperature is of importance in such contexts, the temperature dependency of the thermodynamic functions is also considered here. Uncertainties remain concerning especially katoite, and some low temperature zeolites like phillipsite, chabazite or gismondine

  8. Municipal solid waste ash as a cement raw material substitute

    OpenAIRE

    Somnuk Tangtermsirikul; Pichaya Rachdawong; Kritsada Sisomphon

    2000-01-01

    An investigation of using municipal solid waste (MSW) ash as a cement raw material substitute was performed to evaluate the potential use of ash in construction. The use of incineratior ash in cement production would not only get rid of the ash, but also alleviate many environmental problems, for example, reducing raw materials required for cement production, reducing CO2 emission into the atmosphere, and reducing landfill space requirement for the residue ash disposal. The metallic oxide con...

  9. 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...

  10. 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...

  11. Experimental evaluation of cement materials for solidifying sodium nitrate

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  13. 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

  14. Natural Radioactivity in Tanzania Cements and their Raw Materials

    OpenAIRE

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

    2014-01-01

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

  15. 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.

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

    International Nuclear Information System (INIS)

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

  17. 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.

  18. 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.

  19. 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...... was observed to increase when (a) the inlet oxygen concentration decreased, (b) the temperature increased, and (c) when the total surface area of the fuel particles increased. The type of fuel also had a significant effect on the SO2 release. The sequence of SO2 release for fuel particles in the size interval...

  20. 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

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

    OpenAIRE

    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 shrinkage. Continuous cement hydration also guarantees a strong bond between aggregate, fewer voids, and depercoliation of capillary pores. Thus, a properly cured cement-based material is prepared for...

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. Utilization of Palm Oil Clinker as Cement Replacement Material

    OpenAIRE

    Jegathish Kanadasan; Hashim Abdul Razak

    2015-01-01

    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 pa...

  8. 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

  9. Chloride binding of cement-based materials subjected to external chloride environment - A review

    OpenAIRE

    Yuan, Q.; Shi, C; Schutter, G. de; Audenaert, K.; Deng, D.

    2009-01-01

    This paper reviews the chloride binding of cement-based materials subjected to external chloride environments. Chloride ion exist either in the pore solution, chemically bound to the hydration products, or physically held to the surface of the hydration products. Chloride binding of cement-based material is very complicated and influenced by many factors, such as chloride concentration, cement composition, hydroxyl concentration, cation of chloride salt, temperature, supplementary cementing m...

  10. International Workshop Sustainable and Science-driven Engineering of Cement-based Materials (SSEC 2011)

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    On fundamental scientific research, the thermodynamics and kinetics of hydration of cements are introduced and used to optimize the formation of cement hydrates and accordingly the microstructure of cement-based materials.

  11. CO2 Sequestraion by Mineral Carbonation of Cement Material

    Science.gov (United States)

    Jo, H.; Jang, Y.

    2010-12-01

    CO2 sequestration by mineral carbonation with cement materials was investigated in this study. Ca extraction and CO2 injection tests were conducted on three different materials (lime, Portland cement, waste concrete) using different extract reagents (NH4Cl, CH3COOH, HCl, and Deionized water) under ambient temperature and pressure conditions. CO2 gas (99.9%) was injected to either supernatant without solids or suspension with solids obtained from extraction tests at 4 ml/min of flow rate. Ca concentrations were measured from filtered solutions before and after CO2 injection. The chemical and mineralogical composition of raw materials and precipitates were determined using X-ray fluorescence and X-ray diffraction, respectively. The morphology and chemical composition of precipitates were analyzed with Field Emission Scanning Electron Microscopy equipped with the Energy Dispersive X-ray analysis. For the extraction tests, Ca concentrations of the extracts were related with the CaO content and type of CaO bearing minerals of the materials, regardless of the extraction solutions. Lime had a higher Ca concentration ranging between 942.7 and 39945.0 mg/L in the extracts than waste concrete (188.4 ~ 2978.1 mg/L) in the extracts due to its higher content of CaO (CaO : 24.5% and waste concrete : 20.3%). In contrast, the Portland cement (6346.0 and 28903.5 mg/L) had lower Ca concentrations than lime (94.27 ~ 39945.0 mg/L), even though the Portland cement (56.3%) had a higher CaO content than lime (24.5%). For a given extraction solution, lime had the highest CO2 carbonation efficiency. In addition, for a given material, the CO2 carbonation efficiency was the highest when NH4Cl solution was used as an extraction solution. Results of material analyses indicate that precipitates from the CO2 injection tests consisted of mostly CaCO3, regardless of types of materials and extraction solutions.

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

    DEFF Research Database (Denmark)

    Krejcirikova, Barbora; Goltermann, Per; Hodicky, Kamil

    2013-01-01

    Sewage sludge ash is characterized by its pozzolanic properties, as cement is. This predetermines its use in a substitution of cement and cementitious materials. Utilization of sewage sludge ash does not only decrease the consumption of cement, one of the largest cause of CO2 emissions, but also...

  13. Characterization of cement-based ancient building materials in support of repository seal materials studies

    International Nuclear Information System (INIS)

    Ancient mortars and plasters collected from Greek and Cypriot structures dating to about 5500 BC have been investigated because of their remarkable durability. The characteristics and performance of these and other ancient cementitious materials have been considered in the light of providing information on longevity of concrete materials for sealing nuclear waste geological repositories. The matrices of these composite materials have been characterized and classified into four categories: (1) gypsum cements; (2) hydraulic hydrated lime and hydrated-lime cements; (3) hydraulic aluminous and ferruginous hydrated-lime cements (+- siliceous components); and (4) pozzolana/hydrated-lime cements. Most of the materials investigated, including linings of ore-washing basins and cisterns used to hold water, are in categories (2) and (3). The aggregates used included carbonates, sandstones, shales, schists, volcanic and pyroclastic rocks, and ore minerals, many of which represent host rock types of stratigraphic components of a salt repository. Numerous methods were used to characterize the materials chemically, mineralogically, and microstructurally and to elucidate aspects of both the technology that produced them and their response to the environmental exposure throughout their centuries of existence. Their remarkable properties are the result of a combination of chemical (mineralogical) and microstructural factors. Durability was found to be affected by matrix mineralogy, particle size and porosity, and aggregate type, grading, and proportioning, as well as method of placement and exposure conditions. Similar factors govern the potential for durability of modern portland cement-containing materials, which are candidates for repository sealing. 29 references, 29 figures, 6 tables

  14. 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

  15. Alkali hydrolysis experiment of organic materials such as cement additives

    Energy Technology Data Exchange (ETDEWEB)

    Fukumoto, M. [Japan Nuclear Cycle Development Inst., Tokai Works, Waste Management and Fuel Cycle Research Center, Tokai, Ibaraki (Japan); Nishikawa, Y. [Inspection Development Company Ltd., Tokai, Ibaraki (Japan)

    2001-03-01

    The alkali hydrolysis experiments which seem to be important from the view point of the alteration mechanism using the following seven organic materials was performed as a part of the evaluation of the influence on the disposal of the organic materials contained in the TRU wastes. As a result of the alkali hydrolysis experiments (90degC and 91d), each organic materials became those of lower molecular weight. The degradation products were able to be detected in the solution. The organic materials seem to be degraded to the organic matters which were confirmed in this study in a long term of disposal. The degradation products were shown below. Therefore, the evaluation of the influence on the migration of radionuclides by degradation products becomes important in the future. 1) Cement additives of Naphthalenesulfonic acid and Ligninsulfonic acid ({yields} Naphthalenedisulfonic acid etc.). 2) Cement additives of polycarboxylic acid ({yields} Oligomer of distal methoxypoly ethylene glycol.) 3) Ethylenediamine-N,N,N',N'-tetraacetic acid disodium salt ({yields} Acetic acid desorbed and cyclized organic matters from EDTA). 4) Tributyl phosphate ({yields} Dibutyl phthalate, n-butanol). 5) Poly vinyl acetate ({yields} Acetic acid). 6) Nylon66 ({yields} Adipic acid, Hexamethylenediamine). 7) Cured epoxy resin ({yields} Glycerol poly glycidyl ether, Carboxylic acid). (author)

  16. Properties of Cement Based Materials Containing Copper Tailings

    OpenAIRE

    Onuaguluchi, Obinna

    2012-01-01

    ABSTRACT: Increasing demands for copper and copper allied products have made the processing of low grade ores with high volume waste output unavoidable. Presently, billions of tons of copper tailings can be found in major copper producing countries. This study explored the possibility of using these copper tailings either as a cement replacement or additive material in pastes, mortars and concretes of 0.65, 0.57 and 0.50 w/b ratios. Fresh properties of mixtures such as paste consistencies an...

  17. Sodium Metasilicate Cemented Analogue Material and Its Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Songlin Yue

    2016-01-01

    Full Text Available Analogue material with appropriate properties is of great importance to the reliability of geomechanical model test, which is one of the mostly used approaches in field of geotechnical research. In this paper, a new type of analogue material is developed, which is composed of coarse aggregate (quartz sand and/or barite sand, fine aggregate (barite powder, and cementitious material (anhydrous sodium silicate. The components of each raw material are the key influencing factors, which significantly affect the physical and mechanical parameters of analogue materials. In order to establish the relationship between parameters and factors, the material properties including density, Young’s modulus, uniaxial compressive strength, and tensile strength were investigated by a series of orthogonal experiments with hundreds of samples. By orthogonal regression analysis, the regression equations of each parameter were obtained based on experimental data, which can predict the properties of the developed analogue materials according to proportions. The experiments and applications indicate that sodium metasilicate cemented analogue material is a type of low-strength and low-modulus material with designable density, which is insensitive to humidity and temperature and satisfies mechanical scaling criteria for weak rock or soft geological materials. Moreover, the developed material can be easily cast into structures with complex geometry shapes and simulate the deformation and failure processes of prototype rocks.

  18. 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.

  19. 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

  20. 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.

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

    OpenAIRE

    Li Luo; Yimin Zhang; Shenxu Bao; Tiejun Chen

    2016-01-01

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

  2. Pulmonary bone cement embolism: CT angiographic evaluation with material decomposition using gemstone special imaging

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Sun; Lee, Heon [Dept. of Radiology, Soonchunhyang University Hospital Bucheon, Bucheon (Korea, Republic of)

    2014-08-15

    We report a case of pulmonary bone cement embolism in a female who presented with dyspnea following multiple sessions of vertebroplasty. She underwent spectral CT pulmonary angiography and the diagnosis was made based on enhanced visualization of radiopaque cement material in the pulmonary arteries and a corresponding decrease in the parenchymal iodine content. Here, we describe the CT angiography findings of bone cement embolism with special emphasis on the potential benefits of spectral imaging, providing additional information on the material composition.

  3. 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.

  4. Performance Comparison between EAFD and Conventional Supplementary Cementing Materials

    Directory of Open Access Journals (Sweden)

    Amir Fauzi Hasbi

    2016-02-01

    Full Text Available Sustainability of concrete construction necessitates exploring potential renewable resource, especially from industrial waste products.  Electric arc furnace dust (EAFD, a by-product of the modern electric arc furnace (EAF process from the steel manufacturing industry has an adverse impact on the environment. Utilizing EAFD in concrete production as a cement replacement material together with silica fume (SF and fly ash (FA has raised the interest of many researchers.  This study investigates the use optimum 5% EAFD content refers to both 15% SF and 20% FA in water binder ratio of 0.5 and sand to cement ratio of 2. The aim of this study is to obtain the percentage replacement levels of EAFD that are equivalent to the SF and FA regarding workability, setting time, compressive strength and resistance to rapid chloride permeability. The compressive strength results showed that replacement of 5% SF and 15% FA are the equivalent replacement levels to 3% EAFD. Similarly, results from resistance to rapid chloride permeability showed that the optimum EAFD content performed better than the replacement levels of FA.  However, SF replacement levels showed the best resistance to rapid chloride permeability. Therefore, 3% replacement of EAFD provided an intermediate performance between the optimum SF and FA contents and exceeded that of the control.

  5. 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.

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

    OpenAIRE

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

  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. 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.

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

    OpenAIRE

    Miroslav Matijaca; Slavko Vujec

    1990-01-01

    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 signific...

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

    Directory of Open Access Journals (Sweden)

    Li Luo

    2016-01-01

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

  12. 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.

  13. Experimental research on reflected neutrons from cement material

    International Nuclear Information System (INIS)

    Neutrons reflected by the cement material were studied by nuclear fission and activation methods with a D-T neutron source. With the small enriched uranium and depleted uranium fission ionization chambers combining to the capturing detector, the 235U (wrapped by Cd foil) and 238U fission reaction rates induced by reflected neutrons are measured on the horizontal equator of the Fe shell's outer surface. The standard experimental uncertainties of fission reaction rates were 6.1%-7.3% for 235U(wrapped by Cd foil) and 6.4%-7.4% for 238U. With five kinds of activation foils of different threshold energy, the 56Fe, 27Al, 93Nb, 19F and 63Cu reaction rates induced by reflected neutrons were measured. The standard experimental uncertainties of activation reaction rates were 7.2%-8.0%. The 235U(wrapped by Cd foil) fission reaction rates with a 252Cf neutron source were compared to the ones with a D-T neutron source. The experimental results were discussed and analyzed. (authors)

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

    International Nuclear Information System (INIS)

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

  15. 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 ...

  16. 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...

  17. Microwave processing of cement and concrete materials – towards an industrial reality?

    Energy Technology Data Exchange (ETDEWEB)

    Buttress, Adam, E-mail: adam.buttress@nottingham.ac.uk; Jones, Aled; Kingman, Sam

    2015-02-15

    Each year a substantial body of literature is published on the use of microwave to process cement and concrete materials. Yet to date, very few if any have lead the realisation of a commercial scale industrial system and is the context under which this review has been undertaken. The state-of the–art is evaluated for opportunities, and the key barriers to the development of new microwave-based processing techniques to enhance production, processing and recycling of cement and concrete materials. Applications reviewed include pyro-processing of cement clinker; accelerated curing, non-destructive testing and evaluation (NDT&E), and end-of-life processing including radionuclide decontamination.

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

    OpenAIRE

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

    2011-01-01

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

  19. 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.

  20. 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.

  1. 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

  2. Properties of low-ph cement grout as a sealing material for the geological disposal of radioactive waste

    International Nuclear Information System (INIS)

    The current solution to the problem of using cementitious material for sealing purposes in a final radioactive waste repository is to develop a low-pH cement grout. In this study, the material properties of a low-pH cement grout based on a recipe used at ONKALO are investigated by considering such factors as pH variation, compressive strength, dynamic modulus, and hydraulic conductivity by using silica fume and micro-cement. From the pH measurements of the hardened cement grout, the required pH (< pH 11) is obtained after 130 days of curing. Although the engineering properties of the low-pH cement grout used in this study are inferior to those of conventional high-pH cement grout, the utilization of silica fume and micro-cement effectively meets the long-term environmental and durability requirements for cement grout in a radioactive waste repository

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

    OpenAIRE

    Wei-Wen Li; Wei-Ming Ji; Yi Liu; Feng Xing; Yu-Kai Liu

    2015-01-01

    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 Porosi...

  4. 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

  5. Failure of cemented granular materials under simple compression - Experiments and numerical simulations

    OpenAIRE

    Delenne, Jean-Yves; Topin, Vincent; Radjai, Farhang

    2009-01-01

    We investigate the strength and failure properties of a model cemented granular material under simple compressive deformation. The particles are LECA beads coated by a controlled volume fraction of silicone. The beads are mixed with a joint seal paste (the matrix) and moulded to obtain dense cemented granular samples of cylindrical shape. Several samples are prepared for different volume fractions of the matrix, controlling the porosity, and silicone coating upon which depends the effective p...

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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...... several requirements on its moisture properties. In this paper the frost resistance, the liquid water permeability and the water vapour permeability of cement stabilized gravel are examined for two different cement contents. It is found that a small increase in cement content from 4% to 5% increases...... the 28-days compressive strength from 6.2 MPa to 12.3 MPa. The frost resistance of cement stabilized gravel with 5% cement content is better than for cement stabilized gravel with 4% cement content. The liquid water permeability coefficient and the water vapour permeability coefficient are significantly...

  12. 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...

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

    OpenAIRE

    Syed Zaighum Abbass; Syed Shahid Ali; Jabar Zaman Khan Khattak; Zubair Anwar

    2013-01-01

    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 ...

  14. 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.

  15. 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......-based materials. Beyond the discussion of whether or not the introduction of superabsorbent polymers leads to a strength reduction, this paper uses both experimental and theoretical background to separate the effect of SAP in both pore structure and internal relative humidity and the effect from the active...

  16. 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).

  17. 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......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...

  18. 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

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

    NARCIS (Netherlands)

    Wang, Y.

    2013-01-01

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

  20. 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.

  1. Application progress of solid 29Si, 27Al NMR in the research of cement-based materials

    International Nuclear Information System (INIS)

    Background: The solid-state Nuclear Magnetic Resonance (NMR) is an effective method for the research of cement-based materials. Now it focuses on using solid 29Si and 27Al NMR to research the hydration structure of the cement-based materials in cement chemistry. Purpose: A theoretical guidance is proposed for solid 29Si and 27Al NMR technology used in cement chemistry research. Methods: We reviewed the application of solid 29Si and 27Al NMR in the cement-based materials and analyzed the problem among the researches. Results: This paper introduced an fundamental, relevant-conditions and basic parameters of NMR, and studied the technical parameters of solid 29Si and 27Ai NMR together with the relationship among the hydration structure of cement based material. Moreover, this paper reviewed the related domestic and overseas achievements in the research of hydration structure of the cement-based materials using solid 29Si and 27Al NMR. Conclusion: There were some problems in the research on cement-based materials by technology of solid 29Si and 27Al NMR. NMR will promote the Hydration theory of cement-based material greatly. (authors)

  2. 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. PMID:24840196

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

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

    DEFF Research Database (Denmark)

    Wu, Min

    Pore structure is one of the most important characteristics of cement based materials. This PhD study focused on using a low (micro-)temperature calorimetry (LTC) and a moisture fixation method to study the pore structure of cement based materials, especially at the nanometric level. Special...

  9. 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.

  10. Patch microstructure in cement-based materials: Fact or artefact?

    International Nuclear Information System (INIS)

    The appearance of patch microstructure, i.e. broad dense and porous regions separated by sharp and distinct boundaries and occurring randomly in bulk and interfacial transition zones, has been reported previously in various site- and laboratory-mixed concretes and mortars. In this paper, evidence is presented to show that patch microstructure is an artefact of sample preparation and does not reflect the true nature of the hydrated cement paste. The appearance of dense patches comes from paste areas that have been ground and polished beyond the epoxy resin intrusion depth. In a backscattered electron image, pores not filled with epoxy are not visible because the signal is generated from the base or side walls of the pores. A modified method for epoxy impregnation, which can achieve a much deeper epoxy penetration than conventional vacuum impregnation, is presented

  11. 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.

  12. DC current-induced curing and ageing phenomena in cement-based materials

    NARCIS (Netherlands)

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

    2014-01-01

    This paper investigates DC current-induced “curing” and ageing phenomena in cement-based materials. Two current densities were used in a DC current regime i.e. mortar cubes were subjected to DC current flow of 1 A/m2 and 100 mA/m2; tap water and calcium hydroxide were external environment. Condition

  13. 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.

  14. 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...

  15. 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).

  16. 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

  17. 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.

  18. Nano-modified cement composites and its applicability as concrete repair material

    Science.gov (United States)

    Manzur, Tanvir

    Nanotechnology or Nano-science, considered the forth industrial revolution, has received considerable attention in the past decade. The physical properties of a nano-scaled material are entirely different than that of bulk materials. With the emerging nanotechnology, one can build material block atom by atom. Therefore, through nanotechnology it is possible to enhance and control the physical properties of materials to a great extent. Composites such as concrete materials have very high strength and Young's modulus but relatively low toughness and ductility due to their covalent bonding between atoms and lacking of slip systems in the crystal structures. However, the strength and life of concrete structures are determined by the microstructure and mass transfer at nano scale. Cementitious composites are amenable to manipulation through nanotechnology due to the physical behavior and size of hydration products. Carbon nanotubes (CNT) are nearly ideal reinforcing agent due to extremely high aspect ratios and ultra high strengths. So there is a great potential to utilize CNT in producing new cement based composite materials. It is evident from the review of past literature that mechanical properties of nanotubes reinforced cementitious composites have been highly variable. Some researches yielded improvement in performance of CNT-cement composites as compared to plain cement samples, while other resulted in inconsequential changes in mechanical properties. Even in some cases considerable less strengths and modulus were obtained. Another major difficulty of producing CNT reinforced cementitious composites is the attainment of homogeneous dispersion of nanotubes into cement but no standard procedures to mix CNT within the cement is available. CNT attract more water to adhere to their surface due to their high aspect ratio which eventually results in less workability of the cement mix. Therefore, it is extremely important to develop a suitable mixing technique and an

  19. The influence of superabsorbent polymers on the autogenous shrinkage properties of cement pastes with supplementary cementitious materials

    DEFF Research Database (Denmark)

    Snoeck, D.; Jensen, Ole Mejlhede; De Belie, N.

    2015-01-01

    shrinkage was determined by manual and automated shrinkage measurements. Autogenous shrinkage was reduced in cement pastes with the supplementary cementitious materials versus Portland cement pastes. At later ages, the rate of autogenous shrinkage is higher due to the pozzolanic activity. Internal curing...

  20. Modified sulphur cement: A low porosity encapsulation material for low, medium and alpha waste

    International Nuclear Information System (INIS)

    Modified sulphur cement, available under the trade name Chement 2000, is a thermoplastic candidate material for the matrix of low, intermediate and alpha radioactive waste. The main source of sulphur is the desulphurization of fossil fuels. In view of the future increase of this product a modified compound of sulphur has been developed at the US Bureau of Mines. Modified sulphur cement as matrix material has properties in common with Portland or blast furnace cement and bitumen. The mechanical strength is comparable to hydraulic cement products. The process to incorporate waste materials is identical to bitumization. The leachability and the resistance to attack by chemicals is nearly the same as for bituminized products. This study showed also that the radiation resistance is high without radiolytic gas production and without change in dimensions (swelling). The rigidity of the matrix is a disadvantage when internal pressures are built up. The thermal conductivity and the heat of combustion of sulphur is low resulting in slow damage to the waste form under fire conditions, even when the temperature of self ignition in air is 2200C. The low leachability, the very slow effective diffusion of H2O and HTO, and the low permeability is due to the small pore diameters in the modified sulphur matrix. The loading capacity of modified sulphur cement depends on grain size and distribution and is for ungraded ashes, precipitates, dried sludges, etc., in the order of 40-50% of weight. The price of Chement 2000 per tonne is equal to those of blown bitumen

  1. 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......In fibre reinforced brittle matrix composites the mechanicalbehaviour of the interface between the fibres and the matrix has avery significant influence on the overall mechanical behaviour ofthe composite material. Since brittle matrix composites are designed primarilywith the aim of improving...... debonding of the fibre-matrix interface, it is clear thatspecial emphasis should be put on the mechanical and strengthproperties of the interface. The present paper gives an overview of the different modelsapplied in the literature in the description of interfaces incementitious composite materials...

  2. 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.

  3. Calibration curves of a PGNAA system for cement raw material analysis using the MCNP code

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Carlos; Salgado, Jose

    1998-12-01

    In large samples, the {gamma}-ray count rate of a prompt gamma neutron activation analysis system is a multi-variable function of the elemental dry composition, density, water content and thickness of the material. The experimental calibration curves require tremendous laboratory work, using a great number of standards with well-known compositions. Although a Monte Carlo simulation study does not avoid the experimental calibration work, it reduces the number of experimental calibration standards. This paper is part of a feasibility study for a PGNAA system for on-line continuous characterisation of cement raw material conveyed on a belt (Oliveira, C., Salgado, J. and Carvalho, F. G. (1997) Optimisation of PGNAA instrument design for cement raw materials using the MCNP code. J. Radioanal. Nucl. Chem. 216(2), 191-198; Oliveira, C., Salgado, J., Goncalves, I. F., Carvalho, F. G. and Leitao, F. (1997a) A Monte Carlo study of the influence of geometry arrangements and structural materials on a PGNAA system performance for cement raw materials analysis. Appl. Radiat. Isot. (accepted); Oliveira, C., Salgado, J. and Leitao, F. (1997b) Density and water content corrections in the gamma count rate of a PGNAA system for cement raw material analysis using the MCNP code. Appl. Radiat. Isot. (accepted).]. It reports on the influence of the density, mass water content and thickness on the calibration curves of the PGNAA system. The MCNP-4A code, running in a Pentium-PC and in a DEC workstation, was used to simulate the PGNAA configuration system.

  4. Calibration curves of a PGNAA system for cement raw material analysis using the MCNP code

    International Nuclear Information System (INIS)

    In large samples, the γ-ray count rate of a prompt gamma neutron activation analysis system is a multi-variable function of the elemental dry composition, density, water content and thickness of the material. The experimental calibration curves require tremendous laboratory work, using a great number of standards with well-known compositions. Although a Monte Carlo simulation study does not avoid the experimental calibration work, it reduces the number of experimental calibration standards. This paper is part of a feasibility study for a PGNAA system for on-line continuous characterisation of cement raw material conveyed on a belt (Oliveira, C., Salgado, J. and Carvalho, F. G. (1997) Optimisation of PGNAA instrument design for cement raw materials using the MCNP code. J. Radioanal. Nucl. Chem. 216(2), 191-198; Oliveira, C., Salgado, J., Goncalves, I. F., Carvalho, F. G. and Leitao, F. (1997a) A Monte Carlo study of the influence of geometry arrangements and structural materials on a PGNAA system performance for cement raw materials analysis. Appl. Radiat. Isot. (accepted); Oliveira, C., Salgado, J. and Leitao, F. (1997b) Density and water content corrections in the gamma count rate of a PGNAA system for cement raw material analysis using the MCNP code. Appl. Radiat. Isot. (accepted).]. It reports on the influence of the density, mass water content and thickness on the calibration curves of the PGNAA system. The MCNP-4A code, running in a Pentium-PC and in a DEC workstation, was used to simulate the PGNAA configuration system

  5. ASR mitigation by the use of supplementary cementing materials : evaluation of the available alkali content

    Energy Technology Data Exchange (ETDEWEB)

    Duchesne, J. [Laval Univ., Quebec City, PQ (Canada). Dept. of Geology and Geological Engineering

    2006-07-01

    Cement companies in Canada are involved in the global initiative to voluntarily implement strategies to address global warming, enhance occupational health and safety, reduce emissions, and use fuels and raw materials in a sustainable manner. This paper reported on a study in which the behaviour of common supplementary cementing materials (SCMs) were compared with an industrial by-product from the aluminium industry (ABP). The alkali content in SCMs is particularly critical in terms of its ability to prevent excessive expansion due to alkali-silica reactivity (ASR). The 6 common SCMs with various total alkali contents were: 2 condensed silica fumes, 3 pulverized fly ashes and 1 ground granulated blast furnace slag. The ABP was also investigated as a suitable candidate to replace Portland cement. The testing program involved measuring the expansion and alkali content. The methods used to evaluate the amount of available alkalies were ASTM C114; ASTM C311; modified ASTM C311; pore fluid expression; and, the accelerated mortar bar method. The main objectives of this study were to determine the best procedure for evaluating the amount of available alkalies from SCMs and to discuss the relationship between concrete expansion and alkali content. The recommended methods to evaluate the performance of non usual SCM as suitable candidates to replace Portland cement in the presence of potentially reactive aggregates were accelerated mortar bar method CSA A23.2-25A as well as the available alkalies from cement-SCM paste samples measured by the pore solution expression method. 10 refs., 2 tabs., 2 figs.

  6. Evaluation of meteoric calcite cements as a proxy material for mass-47 clumped isotope thermometry

    Science.gov (United States)

    Defliese, William F.; Lohmann, Kyger C.

    2016-01-01

    Meteoric diagenetic cements are ubiquitous throughout geologic history, affecting most carbonate exposures worldwide. They can often be difficult to interpret, as it is usually difficult to separate the influences of water δ18O and temperature on isotopic signals contained within the carbonate rock body. Despite this difficulty in interpretation, meteoric phreatic cements can potentially be a useful proxy material, as they form slowly in equilibrium at mean annual temperature and are not affected by any biogenic effects that can bias other proxy materials. We applied the mass-47 clumped isotope paleothermometer to Pleistocene and Holocene carbonates from Bermuda and Barbados in order to investigate the effects of meteoric diagenesis on Δ47 signals, and to determine their suitability as a paleotemperature proxy. Phreatic calcite cements are found to record the same temperatures as unaltered carbonate sediments, while any sample exhibiting vadose characteristics is biased towards unreasonably hot apparent formation temperatures. Burial heating and re-equilibration are not geologically viable explanations for the anomalously hot temperatures recorded in vadose cements, as neither Bermuda or Barbados has any burial history. Instead, it is likely that precipitation in the vadose zone occurs on timescales quicker than isotopic equilibrium can be achieved, driven by a combination of CO2 degassing and evaporation, which have been previously shown to cause problems in speleothems and pedogenic carbonates. We conclude by suggesting that meteoric phreatic calcites may be an ideal phase for paleotemperature reconstruction, as they accurately record mean annual temperatures and form under equilibrium conditions, while also being resistant to further mineral driven diagenesis. Vadose cements, and any sample likely affected by processes similar to vadose diagenesis, should be avoided for climate reconstructions using the mass-47 clumped isotope thermometer.

  7. Mechanistic study and modeling of radionuclides retention by the hydrated calcium silicates (HCS) of cements; Etude mecanistique et modelisation de la retention de radionucleides par les silicates de calcium hydrates (CSH) des ciments

    Energy Technology Data Exchange (ETDEWEB)

    Pointeau, I

    2000-09-01

    This work attempts to investigate the modelling of radioisotopes (Cs{sup +}, Pb{sup 2+}, Eu{sup 3+}) immobilization in cement matrix, in the frame of the design of engineered barrier of a deep radwaste repository. The model development concept consists of three major steps: - surface chemistry modelling of the calcium silicate hydrate CSH, used to simulate hydrated cement behaviour; - solid analysis of the batch sorption experiments: identification of the uptake mechanism; - both previous steps are used, with isotherm data, in the modelling of the radioisotopes immobilization in the CSH matrix. Final results: (all modelling are available for all the range of studied Ca/Si ratios and have been validated with predictive calculations). - A thermodynamic modelling of the CSH surface chemistry has been developed. The labile calcium and proton sorption constants on silanol sites (>SiOH) have been extracted. - Cs{sup +} is sorbed on two sites. The silanol site (weak site) has a high site density (10 sites.nm{sup -2}), which accounts for the CSH unsaturation in high [CS{sup +}]. A strong site is also identified. - Pb{sup 2+} immobilization in CSH matrix is modelled with surface equilibria and solubility equilibrium. - Eu{sup 3+} fixation has been investigated with solid analysis: Site-Selective anti Time-Resolved Luminescence Spectroscopy, XPS and SEM-EDS. Eu{sup 3+} thus does not precipitate in CSH water but is sorbed on the CSH surface (high hydroxylated environment). Europium is also (minority site) inserted in the CSH framework. (author)

  8. Study of Concrete Strain for T-Beams Retrofitting by Poly-Urethane-Cement Material (PUC

    Directory of Open Access Journals (Sweden)

    Haleem K. Hussain

    2013-03-01

    Full Text Available Based on the use of Poly-Urethane-Cement composite material to strengthen the concrete structure element, this study concern of the strain induced in concrete and steel bar of control beam and retrofitted beams with PUC. This is a new technique of externally strengthen the Concrete girder beams, control beam (RC were constructed same in all cases and tested under four-point bending load. The objectives of this study are to examine the flexural bending strain of retrofitted beam with Poly-Urethane-Cement material (PUC. Experimental results show the PUC have highly deformation and improving the stiffness of beams. The retrofitting beams with PUC have highly deformed comparing with control beam.

  9. 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

    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...... 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...... under reducing conditions. Particularly, CaSO4 was sensitive to reducing conditions. The sulfur release was most significant if the gas atmosphere frequently shifted between oxidizing and reducing conditions. An increasing temperature from 900 to 1100 °C under alternating oxidizing and reducing...

  10. NTERACTION BETWEEN SURFACE CHARGE PHENOMENA AND MULTI-SPECIES DIFFUSION IN CEMENT BASED MATERIALS

    DEFF Research Database (Denmark)

    Johannesson, Björn

    2008-01-01

    , is one possible explanation for the observed low global diffusion rates in the pore system of positively charged ions compared to the negatively charged ones. Here it is of interest to simulate the multi ionic diffusion behavior when assigning positively charged ions a comparably lower diffusion constant......Measurements strongly indicate that the ‘inner’ surface of the microscopic structure of cement based materials has a fixed negative charge. This charge contributes to the formation of so-called electrical double layers. In the case of cement based materials the ionic species located in such layers...... and also including a negatively charged ‘ion’ with an extremely low diffusion constant so as to represent a fixed negative surface charge. The theoretical results from such simulations, using a tailor made finite element technique, indicates a strong influence of surface charges on global diffusion...

  11. Moisture transport properties of cement-based materials for engineered barriers in radioactive waste disposal

    International Nuclear Information System (INIS)

    This paper reviews the multiphase modeling of moisture transport process in pore structure of cement-based materials used as engineered barriers in radioactive waste disposal. The emphasis is put on the fundamental relationship of moisture isotherm and the related hysteresis phenomenon. A typical cement-based material is retained for study and its properties for moisture transport were measured. The pore structure was characterized by mercury intrusion porosimetry (MIP) and gravimetry method. The moisture isotherm was measured in laboratory by humidity equilibrium method and the predicted isotherm from MIP pore structure is confronted with the measured isotherm. Afterwards, a numerical scheme is set up for the multiphase transport model and the model is applied to the moisture transport process of engineered barriers exposed to natural drying and drying-wetting cycles. It is observed that the ratio between drying and wetting periods has strong influence on the depth of surface convection zone. (authors)

  12. Potential of Carbon Nanotube Reinforced Cement Composites as Concrete Repair Material

    OpenAIRE

    Tanvir Manzur; Nur Yazdani; Md. Abul Bashar Emon

    2016-01-01

    Carbon nanotubes (CNTs) are a virtually ideal reinforcing agent due to extremely high aspect ratios and ultra high strengths. It is evident from contemporary research that utilization of CNT in producing new cement-based composite materials has a great potential. Consequently, possible practical application of CNT reinforced cementitious composites has immense prospect in the field of applied nanotechnology within construction industry. Several repair, retrofit, and strengthening techniques a...

  13. Silicon Carbide Coating for Carbon Materials Produced by a Pack-Cementation Process

    OpenAIRE

    Paccaud, O.; Derré, A.

    1995-01-01

    A pack-cementation process has been developed in order to produce SiC coating on carbon materials. At high temperature gaseous silicon monoxide generated from a SiC-SiO2 powders mixture reacts with carbon substrate by converting the outer surfaces into silicon carbide. The correlation between density measurements and thermochemical calculations allows to determine the reaction path mechanism for the SiC layer formation. Iridium marker experiments are proposed to localize the substrate initial...

  14. Indirect measurement of the ice content curve of partially frozen cement based materials

    OpenAIRE

    Fabbri, Antonin; FEN CHONG, Teddy

    2013-01-01

    The goal of this paper is to investigate the validity of indirectly built ice content curves from porous network characterization tests to predict the behavior of a freezing cement based material. To do so, the results obtained by the two classical methods, namely the mercury intrusion porosimetry (MIP) and the gravimetric water desorption (WD) tests, are compared with the direct measurement of the ice content with a dielectric capacitive apparatus. A corrective approach, based on an interfac...

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

    OpenAIRE

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

    2010-01-01

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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Grinding Characteristics of Multi-component Cement-based Material

    Institute of Scientific and Technical Information of China (English)

    LU Difen; TAO Longzhong; LI Ning; HU Haipeng

    2005-01-01

    The grinding characteristics of two or multi-component material of clinker with limestone, blast furnace slag and fly ash were studied. Investigation was carried out on the particle size distribution, the Blaine fineness and the sieve residue of the separate and interground products. The relative contents of clinker and limestone in different size fractions of the interground product were examined, and the interaction of two components, which have different grindabilities, was analyzed. The results show there exists a selective grinding effect during intergrinding, one component can help or hinder the grinding of the other. Making good use of this interaction appropriately not only enhances the grindabilities of two or multi-component mixtures, which can promote the grinding process of clinker with industrial wastes, but also improves their particle size distribution and properties.

  1. Immediate impact on the rim zone of cement based materials due to chemical attack

    International Nuclear Information System (INIS)

    Cement based materials are in their widespread application fields exposed to various aqueous environments. This can lead to serious chemical changes affecting the durability of the materials. In particular in the context of service life prediction a detailed knowledge of the reaction mechanisms is a necessary base for the evaluation of the aggressivity of an aqueous medium and this is deduced commonly from long term investigations. However, these processes start immediately at the material/water-interface, when a cementitious system comes into contact with an aqueous solution, altering here the chemical composition and microstructure. This rim zone represents the first hurdle that has to be overcome by an attacking aqueous solution. Therefore, the properties of the surface near area should be closely associated with the further course of deterioration processes by reactive transport. In this context short term exposure experiments with hardened cement paste over 4 and 48 h have been carried out with demineralized water, hard tap water and different sulfate solutions. In order to investigate immediate changes in the near-surface region, depth profile cuts have been performed on the cement paste samples by means of focused ion beam preparation techniques. A scanning beam of Gallium ions is applied to cut a sharp edge in the cement paste surface, providing insights into the composition and microstructure of the upper ten to hundred microns. Electron microscopic investigations on such a section of the rim zone, together with surface sensitive X-ray diffraction accompanied by a detailed characterization of the bulk composition confirm that the properties of the material/water interface are of relevance for the durability of cement based systems in contact with aqueous solutions. In this manner, focused ion beam investigations constitute auspicious tools to contribute to a more sophisticated understanding of the reaction mechanisms. - Highlights: • The chemical

  2. Immediate impact on the rim zone of cement based materials due to chemical attack

    Energy Technology Data Exchange (ETDEWEB)

    Schwotzer, M., E-mail: matthias.schwotzer@kit.edu [Karlsruhe Institute of Technology (KIT), Institute of Functional Interfaces (IFG), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Scherer, T. [Karlsruhe Institute of Technology (KIT), Institute of Nanotechnology (INT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Gerdes, A. [Karlsruhe Institute of Technology (KIT), Institute of Functional Interfaces (IFG), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); University of Applied Sciences Karlsruhe, Institute for Prevention in Construction, Moltkestr. 30, D-76133 Karlsruhe (Germany)

    2015-01-15

    Cement based materials are in their widespread application fields exposed to various aqueous environments. This can lead to serious chemical changes affecting the durability of the materials. In particular in the context of service life prediction a detailed knowledge of the reaction mechanisms is a necessary base for the evaluation of the aggressivity of an aqueous medium and this is deduced commonly from long term investigations. However, these processes start immediately at the material/water-interface, when a cementitious system comes into contact with an aqueous solution, altering here the chemical composition and microstructure. This rim zone represents the first hurdle that has to be overcome by an attacking aqueous solution. Therefore, the properties of the surface near area should be closely associated with the further course of deterioration processes by reactive transport. In this context short term exposure experiments with hardened cement paste over 4 and 48 h have been carried out with demineralized water, hard tap water and different sulfate solutions. In order to investigate immediate changes in the near-surface region, depth profile cuts have been performed on the cement paste samples by means of focused ion beam preparation techniques. A scanning beam of Gallium ions is applied to cut a sharp edge in the cement paste surface, providing insights into the composition and microstructure of the upper ten to hundred microns. Electron microscopic investigations on such a section of the rim zone, together with surface sensitive X-ray diffraction accompanied by a detailed characterization of the bulk composition confirm that the properties of the material/water interface are of relevance for the durability of cement based systems in contact with aqueous solutions. In this manner, focused ion beam investigations constitute auspicious tools to contribute to a more sophisticated understanding of the reaction mechanisms. - Highlights: • The chemical

  3. 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.

  4. 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.)

  5. 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.

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

    Science.gov (United States)

    Yilmaz, Arin; Degirmenci, Nurhayat

    2009-05-01

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

  7. Development of Carbon Nanotube Modified Cement Paste with Microencapsulated Phase-Change Material for Structural–Functional Integrated Application

    Science.gov (United States)

    Cui, Hongzhi; Yang, Shuqing; Memon, Shazim Ali

    2015-01-01

    Microencapsulated phase-change materials (MPCM) can be used to develop a structural–functional integrated cement paste having high heat storage efficiency and suitable mechanical strength. However, the incorporation of MPCM has been found to degrade the mechanical properties of cement based composites. Therefore, in this research, the effect of carbon nanotubes (CNTs) on the properties of MPCM cement paste was evaluated. Test results showed that the incorporation of CNTs in MPCM cement paste accelerated the cement hydration reaction. SEM micrograph showed that CNTs were tightly attached to the cement hydration products. At the age of 28 days, the percentage increase in flexural and compressive strength with different dosage of CNTs was found to be up to 41% and 5% respectively. The optimum dosage of CNTs incorporated in MPCM cement paste was found to be 0.5 wt %. From the thermal performance test, it was found that the cement paste panels incorporated with different percentages of MPCM reduced the temperature measured at the center of the room by up to 4.6 °C. Inverse relationship was found between maximum temperature measured at the center of the room and the dosage of MPCM. PMID:25867476

  8. The Properties of Road Base Course Materials of Granular Soils Stabilized by AGS Granular Soil Stabilizing Cement

    Institute of Scientific and Technical Information of China (English)

    SHEN Wei-guo; ZHOU Ming-kai; ZHAO Qing-lin; WU Shao-peng

    2003-01-01

    The properties of road base course materials of granular soils stabilized by AGS granular soil stabilizing cement[1]were studied.The AGS cement has an expansibility to a certain degree,so the dry shrinkage of AGS cement paste and AGS stabilized granular is much lower than that of Portland slag cement.AGS has a good suitability to granular soils.Granular soils stabilized by AGS have a much higher strength than that of soils stabilized by P S cement.The same strength can be reached with 20% reduction of cement dosage for AGS cement.And their elastic and resilient modulus are similar,but the former has a much higher tensile splitting strength,so the AGS stabilized granular has a much better anti-cracking performance than that of the P S stabilized granular.The reduced value of the strength and the density with the retard time for the granular soils stabilized by AGS is lower than that for P S cement.

  9. [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.

  10. 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.

  11. 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.

  12. 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.

  13. 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...

  14. 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. PMID:26037967

  15. 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

  16. 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.

  17. Characterization and modeling of the rheology of cement paste: With applications toward self-flowing materials

    Science.gov (United States)

    Saak, Aaron Wilbur

    The objective of this research is to better understand the important mechanisms that control the rheology of cement paste. In order to understand these mechanisms, new experimental techniques are developed. The insights gained through these studies are then applied toward designing self-flowing materials, particularly self-compacting concrete (SCC). A new testing program is developed where both the peak and equilibrium stress flow curves of cement paste are obtained by testing only one sample. Additionally, the influence of wall slip on yield stress and viscoelastic measurements is determined using a vane. The results indicate that a slip layer develops when the shear stress approaches the yield point. A three-dimensional model relating slump to yield stress is derived as a function of cone geometry. The results indicate that the model fits experimental data for cylindrical slumps over a wide range of yield stress values for a variety of materials. When compared to other published models, the results suggest that a fundamental relationship exists between yield stress and slump that is material independent and largely independent of cone geometry. The affect of various mixing techniques on the rheology of cement paste is investigated using a rheometer as a highly controlled mixer. The results suggest that there is a characteristic shear rate where the viscosity of cement paste is minimized. The influence of particle packing density, morphology and surface area on the viscosity of cement paste is quantified. The data suggest that even though packing density increases with the addition of fine particles, the benefits are largely overshadowed by a dramatic increase in surface area. Finally, a new methodology is introduced for designing self-compacting concrete. This approach incorporates a "self-flow zone" where the rheology of the paste matrix provides high workability, yet segregation resistance. The flow properties of fresh concrete are measured using a U

  18. 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

  19. Evaluation of red mud as pozzolanic material in replacement of cement for production of mortars

    International Nuclear Information System (INIS)

    Red mud is a by-product of the alkaline extraction of aluminum from the bauxite and represents a renewed environmental problem due the significant annual throughput by the plants. In the present work, the pozzolanic properties of Brazilian red mud fired at 600, 700, 800 and 900 deg C were investigated by monitoring lime consumption using DTA analysis and Brazilian standard methodology NBR 5772 (1992). Products and kinetics of hydration were determined in cement pastes produced with 5 and 15% red mud using x-ray diffraction and DTA analysis. Compressive strength and capillary absorption tests were realized on mortars constituted by 5, 10 and 15% red mud in replacement of cement. When calcined at 600 deg C, the red mud develops good pozzolanic properties, and the compressive strength of mortars produced with this waste meet values in accordance with regulatory standard. These results shown than red mud can be used, in partial replacement of cement, as new construction material to produce sustainable mortars with low environmental impact. (author)

  20. Near-field microwave inspection and characterization of cement based materials

    Science.gov (United States)

    Bois, Karl Joseph

    The objective of this research project has been to investigate the potential of correlating the near-field microwave reflection coefficient properties of hardened cement paste (water and cement powder), mortar (water, cement powder and sand) and concrete (water, cement powder, sand and coarse aggregate) specimens to their various constituent make-up and compressive strengths. The measurements were conducted using open-ended rectangular waveguide probes operating at various microwave frequencies and in-contact with cubic specimens. For each material, various properties of the measured microwave reflection coefficient, such as the mean of the measured magnitude of reflection coefficient, and the standard deviation of the measured magnitude of reflection coefficient at various frequencies were monitored. Subsequently, the measurements were correlated to important parameters such as w/c ratio, s/c ratio, ca/c ratio, cure-state, constituent volume content and compressive strength. Other issues such as the detection of aggregate segregation in concrete as well as the detection chloride in cement paste and mortar were also addressed. Other related issues such as the detection of grout in masonry blocks were also investigated. In achieving these objectives, several theoretical modeling efforts were required, constituting significant contributions to the available literature. A complete analytical full wave expression (i.e. inclusion of higher-order modes) for the fields at the aperture of an open-ended waveguide probe radiating into a dielectric infinite half-space was derived. Also a novel two-port transmission line dielectric property measurement technique for granular and liquid materials was developed. A decision making process, based on the maximum likelihood scheme, was also implemented to determine w/c, s/c and ca/c ratios from the measured mean and standard deviation of reflection coefficient at two frequency bands. Finally, the issue of non-contact measurement was

  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. 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.

  3. 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.

  4. 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.

  5. Study of Concrete Strain for T-Beams Retrofitting by Poly-Urethane-Cement Material (PUC)

    OpenAIRE

    Haleem K. Hussain; Lian Zhen Zhang; Gui Wei Liu

    2013-01-01

    Based on the use of Poly-Urethane-Cement composite material to strengthen the concrete structure element, this study concern of the strain induced in concrete and steel bar of control beam and retrofitted beams with PUC. This is a new technique of externally strengthen the Concrete girder beams, control beam (RC) were constructed same in all cases and tested under four-point bending load. The objectives of this study are to examine the flexural bending strain of retrofitted beam with Poly-Ure...

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

    OpenAIRE

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

    2008-01-01

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

  7. Development of porosity of cement paste blended with supplementary cementitious materials after carbonation

    OpenAIRE

    Wu, B.; YE, guang

    2015-01-01

    Supplementary cementitious materials (SCMs) like fly ash (FA) and blast furnace slag (BFS) are normally used to replace parts of Ordinary Portland cement (OPC) to reduce the cost and CO2 emission. Some consequences are the reduction of portlandite (CH) content and the formation of C-S-H with low Ca/Si ratio, due to pozzolanic reactions. It is known that carbonation of portlandite leads to a reduction in the porosity which is ascribed to the positive difference of molar volumes between CH and ...

  8. Effect of Compressive Loading on Transport Properties of Cement-Based Materials

    Science.gov (United States)

    Hoseini, Meghdad

    The durability of concrete is one of its most important properties and has been an attractive subject for research in recent years. One of the criteria that affect concrete durability is permeability. Transport processes in concrete have been investigated for several decades. However, the correlation between transport coefficients and applied stress has received only little attention. On the other hand, measuring permeability involves a time-consuming test, with attendant concerns about system equilibrium and load control. Non Destructive Testing (NDT) of concrete makes it possible to obtain many test results from a single specimen and thus gives the opportunity to follow the changes in the properties of the specimen with time and under external influences. The scope of this study encompasses two major points of research focus. The first involves developing an experimental model for relating the permeability of cement-based materials under stress through non-destructive means, by measuring the Ultrasonic Pulse Velocity. The second part of this study examines the change in microstructure in cement-based materials under stress by employing x-ray tomography. A new parameter, pore connectivity, is introduced and was found to relate better to the permeability and damage caused by compressive stress. In all cases, the effect of fibre inclusion in mix designs is examined. The results show that both permeability and ultrasonic pulse velocity are stress-dependent and there is a correlation between the change of permeability and ultrasonic pulse velocity in cement-based materials under stress. The proposed permeability-UPV model has shown to have a good accuracy in predicting the permeability of concrete via a Non-Destructive Test method. On the other hand, the presented method for determining the pore connectivity of cement-based materials, has shown a good agreement with the permeability results (which also depend on the interconnectivity of the voids and pores). This

  9. Ink-bottle effect in mercury intrusion porosimetry of cement-based materials.

    Science.gov (United States)

    Moro, F; Böhni, H

    2002-02-01

    Mercury intrusion porosimetry (MIP) is a widely used method for studying porous materials, in particular, cement-based materials. The usual interpretation of such measurements is based on certain assumptions. One of these is that each pore is connected to the sample surface directly or through larger pores. Pores not meeting this assumption are called ink-bottle pores. The effect that sample size has on the MIP characteristics of concrete samples, like the ink-bottle effect and hysteresis, was studied by measuring additional extrusion and intrusion cycles. In order to characterize the extrusion and ink-bottle behavior, the amount of entrapped mercury chi(p) was estimated. Superimposition of extrusion and second intrusion curves is achieved if the contact angle theta is adjusted from theta(i), the intrusion contact angle, to theta(e), the extrusion contact angle. The threshold radius is often assumed to be a dominant pore radius, yet in this study the entrapped mercury content shows no evidence for the presence of a dominant pore radius. Even if characteristic properties of cement-based materials can be estimated with MIP, comparison of results is rendered difficult by the significant effects of sample preparation techniques and sample size and the ink-bottle effect due to randomly present air bubbles. PMID:16290394

  10. 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.

  11. 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.

  12. Jordanian silica sand and cement as a reinforcement material for polystyrene matrix composites

    International Nuclear Information System (INIS)

    The behaviour of polystyrene matrix composites with different percentages of Jordaanian Silica Sand as a Reinforcement Materials (0, 5, 25, 50, and 75 wt%) and different mean grain sizes of sand particles (60, 75, 85, and 300μ m) and with cement as a boning materials in the amount fo 1/6 wt% of the wt% of silica sand were manufactured and tested under compression loading in the Industrial Engineering Department as the Uninersity of Jordan as a part of large study on local materials. The main conclusions of this investigation are: a long-term, durable structure of the polystyrene composite reinforced by silica sand and cement was achieved by mixing the constituents with water; the higher the volume fraction of the reinforcement, the higher the volume fraction of reinforcement, the higher the strength while for 75% of reinforcement, the strength dropped to an amount less than that of the matrix; the higher the grain size, the higher the strength; longitudinal brittle fracture was observed for the composites, and a homogeneous distribution of the sand particles helped in increasing the strength of the composite by playing an important role in distributing the applied load. (author). 11 refs., 6 tabs, 2 figs

  13. Radiolysis in cement-based materials ; application to radioactive waste-forms

    International Nuclear Information System (INIS)

    Cement-based materials appear to be an original environment with respect to radiolysis, due to their intrinsic complexity (porous, multiphasic and evolutional medium) or their very specific physico-chemical conditions (hyper-alkaline medium with pH ≥ 13, high content in calcium) or by the fact of numerous couplings existing between different phenomenologies. At the level of a radioactive cemented wasteform, a high degree of complexity is reached, in particular if the system communicates with the atmosphere (open system allowing regulation of the pressures but also the admission of O2, strong reactive with regards to radiolysis). Then, the radiolysis description exceeds widely the only one aspect of the decomposition of alkaline water under irradiation and makes necessary a global phenomenological approach. In this context, some 'outlying' phenomena, highly coupled with radiation chemistry, have to be taken into account because they contribute to deeply modify the net result of the radiolysis: radioactive decay of multiple αβγ emitters with filiation, phase changes (for example H2 aq → H2 gas) within the pores, gas transport by convection (Darcy law) and by diffusion (Fick law), precipitation/dissolution of solid phases, effect of the ionic strength and the temperature, disturbances connected to the presence of some solutes with redox potentialities (iron, sulphur). The integration work carried out on the previous points leads to an operational model (DOREMI) allowing the estimate of H2 amounts produced by radiolysis in different cemented radioactive waste-forms. As the final expression of the model, numerical simulations constitute a relevant tool of expertise and prospecting, contributing to accompany the thought on radiolysis in cement matrices in general and in cemented waste-forms in particular. Starting from different examples, simulations can be so used in order to test some hypotheses or illustrate the greatest influence of gas transport, dose rate

  14. Analysis of cement-bonded materials by multi-cycle mercury intrusion and nitrogen sorption.

    Science.gov (United States)

    Kaufmann, Josef; Loser, Roman; Leemann, Andreas

    2009-08-15

    The pore systems of cement-based materials are studied by N(2) sorption and mercury intrusion porosimetry (MIP). Pore size distributions and internal surfaces are derived. Especially in materials with a broad pore size distribution, these (and other) methods generally do not lead to coincident results. It is shown here, how the interpretation of the experimental data of the two methods may be modified in order to obtain coincident pore size distributions from both methods. The studied pore systems are described as array of chambers which are connected by smaller throats. N(2) adsorption is used to calculate the size of the pores, whereby no distinction between throat or chamber type is possible with this method. Assuming mercury entrapping in ink-bottle type pores (pores that are connected to an external surface through smaller pores only) being the dominant process for mercury snap-off during extrusion and applying multi-cycle MIP, the calculation of the size of the entrances of these ink-bottles is possible. It is shown that similar results also may be derived from mercury extrusion data by applying a contact angle correction for the retracting mercury meniscus. A good agreement of the pore size distribution of the connected, non-ink-bottle type pores derived from either N(2) sorption or mercury intrusion is obtained. Samples of cement paste and mortar are analysed. A significant difference between cement paste and mortar regarding the neck entrances of ink-bottle type pores is found and attributed to the coarse pore space around the aggregates, the interfacial transition zone. PMID:19505695

  15. 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.

  16. Selecting of Cementing Material in Green Lightweight Concrete with Oil Palm Shell (OPS

    Directory of Open Access Journals (Sweden)

    Mohamad Ibrahim Mohamad

    2012-06-01

    Full Text Available Floating urbanization could be the subject of a green flood mitigation strategy. The main part of any floating house is the buoyant part, which is made from concrete pontoons. Aggregates play the most important role in making concrete a lightweight material. Oil Palm Shell (OPS is an agricultural waste material, which is widely available in South East Asia. This study tries to select the best cementing material from waste and produced pozzolans, to improve the specifications of green lightweight concrete with Oil Palm Shell (OPS, using decision-making methods. The decision making model was conducted by the application of a Fuzzy Preference Selection Index (PSI. Quantitative data was obtained from laboratory testing, which was translated into fuzzy functions, and qualitative data was obtained through verbal interviews. Silica Fume (SF contributed the best performance of all pozzolans, with a 25% replacement in green lightweight concrete, with Oil Palm Shell (OPS.

  17. 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.

  18. 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.

  19. 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.

  20. Material characterization and non destructive testing by ultrasounds; modelling, simulation and experimental validation; Caracterisation des materiaux et controle non destructif par ultrasons; modelisation, simulation et validation experimentale

    Energy Technology Data Exchange (ETDEWEB)

    Noroy-Nadal, M.H

    2002-06-15

    This memory presents the research concerning the characterization of materials and the Non Destructive Testing (N.D.T) by ultrasonics. The different topics include three steps: modeling, computations and experimental validation. The studied materials concern mainly metals. The memory is divided in four parts. The first one concerns the characterization of materials versus temperature. The determination of the shear modulus G(T) is especially studied for a large temperature range, and around the melting point. The second part is devoted to studies by photothermal devices essentially focused on the modeling of the mechanical displacement and the stress field in coated materials. In this particular field of interest, applications concern either the mechanical characterization of the coating, the defect detection in the structure and finally the evaluation of the coating adhesion. The third section is dedicated to microstructural characterization using acoustic microscopy. The evaluation of crystallographic texture is especially approached, for metallic objects obtained by forming. Before concluding and pointing out some perspectives to this work, the last section concerns the introduction of optimization techniques, applied to the material characterization by acoustic microscopy. (author)

  1. Modelisation statistique de formes en imagerie cerebrale

    OpenAIRE

    Corouge, Isabelle

    2003-01-01

    Cette these traite de la modelisation statistique de formes en imageriecerebrale.Dans une premiere partie, nous proposons un modele statistique de la forme des sillons corticaux. Le modele est bati par apprentissage a partir de sillons extraits d'images IRM et dotes d'une representation parametrique. La definition d'un repere intrinseque a la forme sillon permet d'aligner l'ensemble des formes extraites et de construire une population d'apprentissage coherente sur laquelle appliquer une analy...

  2. Multi-scale modeling of materials: from ab-initio calculations to kinetic simulations; Modelisation multiechelle des materiaux de l'ab-initio a la cinetique

    Energy Technology Data Exchange (ETDEWEB)

    Willaime, F. [Division de l' energie nucleaire, CEA Centre de Saclay, 91191 Gif-sur-Yvette (France); Deutsch, T.; Pochet, P. [INAC, Direction des sciences de la matiere, CEA Centre de Grenoble, 38054 Grenoble Cedex 9 (France)

    2010-07-01

    Ab-initio calculation methods, for the purposes of computing electronic structures, have made it possible, since the early nineties, to simulate the properties of perfect crystalline materials (materials free of any defect). By improving such methods, and with the increasing power of supercomputers, it has now become feasible to simulate the properties of elementary defects, which may seldom be accessed directly through experiments. This has opened up a vast, fruitful field of multi-scale simulations, where such data yield the basis for realistic simulations of the kinetics of materials evolution. The kinetic Monte-Carlo method thus provides the means to model phenomena acting at the scale of a second, or even of a year. In the issue of self-diffusion in silicon, multi-scale simulation has been successful in predicting an asymmetrical behaviour: a speeding up of vacancy diffusion under compression and a tailing off under tension, and conversely, a speeding up of interstitial diffusion under tension and a falling off under compression. Multi-scale modeling has also been successful in simulating irradiation defects in iron. (A.C.)

  3. 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.

  4. 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.

  5. 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

  6. First principles simulation of the electrochemical behaviour of lithium battery materials; Modelisation du comportement electrochimique de materiaux pour batteries au lithium a partir de calculs de premiers principes

    Energy Technology Data Exchange (ETDEWEB)

    Rocquefelte, X.

    2001-10-01

    The functioning of a positive electrode in a lithium battery is based on the reversible intercalation of lithium. In some cases, such a reaction can lead to important structural modifications and therefore to an amorphization of the material. A theoretical approach is presented here that leads to structural predictions and simulations of electrochemical behaviour of positive electrode materials. In the first part, DFT (Density Functional Theory) formalisms and the respective advantages of FLAPW (Full potential Linearized Augmented Plane Waves) and PP/PW (Pseudopotential / Plane Waves) methods are discussed. In the second part are given some fundamental electrochemistry considerations related to the intercalation process, thermodynamics aspects and relationships with electronic structure. Then, an approach combining experimental data and geometry optimisation of structural hypotheses is given. This approach was first applied to a model compound LiMoS{sub 2}, and has been then generalised to systems of industrial interest such as Li{sub x}V{sub 2}O{sub 5} (0 {<=} x {<=} 3). The simulated X-ray diagrams of the optimised structures for LiMoS{sub 2} and {omega} - Li{sub 3}V{sub 2}O{sub 5} are in good agreement with experimental data. In the case of Li{sub x}V{sub 2}O{sub 5}, the first discharge curves starting from {alpha} - V{sub 2}O{sub 5} and {gamma}' - V{sub 2}O{sub 5} were then successfully simulated. A chemical bond analysis was carried out to help understand the origin of the distortion in LiMoS{sub 2} and the voltage variations in the electrochemical curves of Li{sub x}V{sub 2}O{sub 5}. This study clearly demonstrates that an approach combining first-principle calculations and available experimental data is invaluable in the structure determination of poorly crystallized compounds. Such a procedure contributes to the understanding of the phase transitions induced by the lithium intercalation in vanadium oxide compounds and can really be used in the research

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

    DEFF Research Database (Denmark)

    Esteves, Luis Pedro

    2015-01-01

    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 of...... superabsorbent polymers in cementitious environments is well determined. It is vital that a generalized agreement over which method should be utilized with this regard is obtained, so large-scale industrial applications can be developed with sufficient quality and safeguards. There ought to be a standard method...... 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...

  8. REMOVAL OF SOLUBLE CR(VI IN CEMENTS BY FERROUS SULPHATE MONOHYDRATE, SOLID LIGNIN AND OTHER MATERIALS

    Directory of Open Access Journals (Sweden)

    T. TUNÇ

    2011-03-01

    Full Text Available Various reducing agents such as ferrous sulphate heptahydrate (HH and monohydrate (MH, solid lignin (SL, Na2S2O4, NaHSO3, SnCl2·2H2O, N2H4·H2O and FeS are used to reduce Cr(VI contents of three types of cements under 2 mg/L, as it is requested by European Parliament Standards. Optimum conversion temperature of HH to MH was found as 130°C, for 20 min., by thermal analysis. Minimum amounts of various agents to be used as additives in cements to reduce Cr(VI contents under the standard value were determined. Minimum reducing agent amounts of SL, MH and their mixture of 1:3 mole fractions were found as 0.44 %, 0.14 %, 0.24 % by weight, respectively for Portland cement (CEM I 42.5 R, 0.40 %, 0.26 %, 0.24 % for Portland Pozzolanic cement (CEM II/A-P 42.5 N and 0.16 %, 0.05 %, 0.04 % for Pozzolanic cement (CEM IV/B (P 32.5 N. Minimum amounts of other materials to reduce Cr(VI content of three type cements under the required value, were found as 0.24 %, 0.16 %, 0.0 9 % (N2H4·H2O, 0.10 %, 0.07 %, 0.04 % (Na2S2O4, 0.04 %, 0.025 %, 0.01 % (SnCl2·2H2O and 0.28 %, 0.27 %, 0.12 % (NaHSO3, respectively. It was found that SL, the MH and their mixture of 1:3 mole fractions can be used successfully as additives for reducing Cr(VI contents of cement. There are two advantages of this usage of MH. It converts Cr(VI to Cr(III and extends the shelf-life of cement. On the other hand, SL reduces Cr(VI and increases durability of cements by lowered water/cement ratio.

  9. 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".

  10. 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...

  11. 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.

  12. POZZOLAN AND CEMENTS WITH POZZOLAN

    OpenAIRE

    Kaplan, Hasan; 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...

  13. The rim zone of cement based materials - barrier or fast lane for chemical degradation?

    International Nuclear Information System (INIS)

    This contribution focuses exemplarily on the chemical and mineralogical changes in the rim zone of cement paste samples exposed to different chloride solutions (NaCl, KCl, MgCl2 and CaCl2), to hard tap water and to demineralized water. The determination of the Ca(OH)2 and Mg(OH)2 content of the solid phases was performed by means of thermogravimetry with pulverized samples (TGA/SDTA 851, Mettler-Toledo). A potential relation between temperature and the time dependant development of the material due to reactive transport processes will also be addressed. The experiments with tap water showed that the contact between the cement paste samples and hard tap water did not lead to significant changes in the composition of the solid samples or of the reaction solution. This can be attributed to a rapid formation of a protective calcium carbonate layer on the surface of the cement paste. The slight decrease of the Ca2+ content in the solution indicates that the growth of this layer occurs within the first few hours. In contrast to the tap water exposure, the results of the experiments with the MgCl2 solutions show features of an intense attack despite the presence of crystalline covering layers. The quick formation of a thick and dense Mg(OH)2 layer does not provide any protection against reactive transport processes. In this experiment, the degradation rate of Ca(OH)2 as well as the Ca2+ release was higher than in all other experiments. In addition the rapid formation of a Mg(OH)2 layer starting already during the first hour of the experiment did not prevent the chloride ingress compared to the other experiments with chloride solutions. The pH value of the reaction solution remains stable and relatively low which indicates a crystallisation process. In the other experiments, performed with demineralized water, alkali chloride solutions, and the CaCl2 solution, no significant formation of potentially protective covering layers and no development of transport inhibiting

  14. Coupling between mechanical behaviour and drying of cementing materials: experimental study on mortars

    International Nuclear Information System (INIS)

    The aim of this work is to understand the desiccation effects on the mechanical behaviour of cement materials. Two mortars of ratio E/C=0.5 and 0.8 have been tested. All the tests have been implemented after a six months maturing in water. The experimental study has been carried out as follows: 1)tests characterizing the differed behaviour and the transport properties have been carried out 2)tests characterizing the short term multiaxial mechanical behaviour have been carried out. The desiccation shrinkage in terms of the weight loss presents three characteristic phases. The permeability measurement on the mortar 05 shows that the permeability of the specimens dried and crept is greater than those of the specimens dried before being crept, and the permeability of the specimens submitted to a desiccation creep and then dried is sensibly the same as the last one in spite of a very important differed deformation. The influence of the desiccation on the uniaxial and deviatoric compressions resistance depends of the binding agent: for a cement paste of good quality (E/C=0.5), the resistances increase with the desiccation because of the capillary depression and of the hydric gradients. For a cement paste of low quality (E/C=0.8), there is a competitive effect between the increase of the microcracks induced and the specimen rigidification; the microcracking becomes then the parameter controlling the rupture process. The elasto-plastic behaviour becomes a damageable elasto-plastic behaviour during desiccation which induces, as the decrease of the E/C ratio, a translation of the elastic limit surfaces and ruptures towards higher stresses. In parallel, the elastic properties and the incompressibility modulus are damaged and the volume deformations increase after the drying. At last, the decrease of the Young modulus and the passage to the third shrinkage phase in terms of the weight loss coincide. This can be attributed to the induced microcracking: this decrease of the

  15. 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.

  16. 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).

  17. Chloride corrosion of embedded reinforced steel on concrete elaborated from recycled coarse aggregates and supplementary cement materials

    OpenAIRE

    Corral Higuera, Ramón; Arredondo Rea, Susana Paola; Almaral Sánchez, Jorge Luis; Gómez Soberón, José Manuel Vicente

    2013-01-01

    As a result of contributive and sustainable strategies on concrete industry, researches are presently being developed, which are focused on improving durability of reinforced concrete structures as well as partially or completely replacing their components by recycled materials. In the case of steel bars, corrosion is considered as the major durability menace to reinforced concrete. The present research employed coarse aggregate from recycled concrete and supplementary cement materials,...

  18. Radon exhalation of cementitious materials made with coal fly ash: Part 1 - scientific background and testing of the cement and fly ash emanation

    International Nuclear Information System (INIS)

    Increased interest in measuring radionuclides and radon concentrations in fly ash, cement and other components of building products is due to the concern of health hazards of naturally occurring radioactive materials (NORM). The current work focuses on studying the influence of fly ash (FA) on radon-exhalation rate (radon flux) from cementitious materials. The tests were carried out on cement paste specimens with different FA contents. The first part of the paper presents the scientific background and describes the experiments, which we designed for testing the radon emanation of the raw materials used in the preparation of the cement-FA pastes. It is found that despite the higher 226Ra content in FA (more than 3 times, compared with Portland cement) the radon emanation is significantly lower in FA (7.65% for cement vs. 0.52% only for FA)

  19. 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...

  20. 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.

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

    Directory of Open Access Journals (Sweden)

    Glen E. Fryxell

    2008-03-01

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

  2. Modelisation of the SECMin molten salts environment

    Science.gov (United States)

    Lucas, M.; Slim, C.; Delpech, S.; di Caprio, D.; Stafiej, J.

    2014-06-01

    We develop a cellular automata modelisation of SECM experiments to study corrosion in molten salt media for generation IV nuclear reactors. The electrodes used in these experiments are cylindrical glass tips with a coaxial metal wire inside. As the result of simulations we obtain the current approach curves of the electrodes with geometries characterized by several values of the ratios of glass to metal area at the tip. We compare these results with predictions of the known analytic expressions, solutions of partial differential equations for flat uniform geometry of the substrate. We present the results for other, more complicated substrate surface geometries e. g. regular saw modulated surface, surface obtained by Eden model process, ...

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

    Directory of Open Access Journals (Sweden)

    Zornoza, E.

    2010-12-01

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

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

  4. 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

    The potential role of near-field colloids for the colloid-facilitated migration of radionuclides has stimulated investigations concerning the generation and presence of colloids in the near-field of a repository for low- and intermediate level waste (L/ILW). The highly gas permeable mortar (Nagra designation: mortar M1) is currently favoured as backfill material for the engineered barrier of the planned Swiss L/ILW repository. The cementitious backfill is considered to be a chemical environment with some potential for colloid generation. In a series of batch-style laboratory experiments the physico-chemical processes controlling the inventory of colloids in cement pore water of the backfill were assessed for chemical conditions prevailing in the initial stage of the cement degradation. In these experiments, backfill mortar M1 or quartz, respectively, which may be used as aggregate material for the backfill, were immersed in artificial cement pore water (a NaOH/KOH rich cement fluid). Colloid concentrations in the cement pore water were recorded as a function of time for different experimental settings. The results indicate that a colloid-colloid interaction process (coagulation) controlled the colloid inventory. The mass concentration of dispersed colloids was found to be typically lower than 0.02 ppm in undisturbed batch systems. An upper-bound value was estimated to be 0.1 ppm taking into account uncertainties on the measurements. To assess the potential for colloid generation in a dynamic system, colloid concentrations were determined in the pore water of a column filled with backfill mortar. The chemical conditions established in the mortar column corresponded to conditions observed in the second stage of the cement degradation (a Ca(OH){sub 2{sup -}} controlled cement system). In this dynamic system, the upper-bound value for the colloid mass concentration was estimated to be 0.1 ppm. Implications for radionuclide mobility were deduced taking into account the

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

    International Nuclear Information System (INIS)

    The potential role of near-field colloids for the colloid-facilitated migration of radionuclides has stimulated investigations concerning the generation and presence of colloids in the near-field of a repository for low- and intermediate level waste (L/ILW). The highly gas permeable mortar (Nagra designation: mortar M1) is currently favoured as backfill material for the engineered barrier of the planned Swiss L/ILW repository. The cementitious backfill is considered to be a chemical environment with some potential for colloid generation. In a series of batch-style laboratory experiments the physico-chemical processes controlling the inventory of colloids in cement pore water of the backfill were assessed for chemical conditions prevailing in the initial stage of the cement degradation. In these experiments, backfill mortar M1 or quartz, respectively, which may be used as aggregate material for the backfill, were immersed in artificial cement pore water (a NaOH/KOH rich cement fluid). Colloid concentrations in the cement pore water were recorded as a function of time for different experimental settings. The results indicate that a colloid-colloid interaction process (coagulation) controlled the colloid inventory. The mass concentration of dispersed colloids was found to be typically lower than 0.02 ppm in undisturbed batch systems. An upper-bound value was estimated to be 0.1 ppm taking into account uncertainties on the measurements. To assess the potential for colloid generation in a dynamic system, colloid concentrations were determined in the pore water of a column filled with backfill mortar. The chemical conditions established in the mortar column corresponded to conditions observed in the second stage of the cement degradation (a Ca(OH)2- controlled cement system). In this dynamic system, the upper-bound value for the colloid mass concentration was estimated to be 0.1 ppm. Implications for radionuclide mobility were deduced taking into account the experimental

  6. 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

  7. Environmental production : use of waste materials in cement kilns in China

    OpenAIRE

    Wang, Ning

    2008-01-01

    This report mainly talks about utilizing the cement kiln to dispose wastes. In China, there are huge amounts of wastes can be produced every year. China government pays more attention to the environmental protection. The government wants to dispose the wastes securely. The cement kiln is a good ‘place’ to take the wastes. The cement kiln has a high temperature, long remaining time, and can solidify the heavy metals, dispose the solid, semi-solid or liquid wastes. To dispose the wa...

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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 tenden...

  14. Studies on cement matrix materials used at the Radioactive Waste Treatment Plant for radwaste conditioning

    International Nuclear Information System (INIS)

    The research activities performed by Department of Radioactive Waste Management is focused on the treatment of LLAW products obtained by chemical precipitation and on the conditioning of these products by cementation. The individual mechanisms implied in the chemical precipitation processes are directly dependent on the precipitate properties and structure, which in turn are connected with the initial system composition and the precipitation procedure, i.e. reagent concentration, rate and orders of chemical addition, mixing rate and time and ageing conditions. In case of conditioning by cementation, the chemical nature and proportion of the sludges or concentrates affect both the hydrolysis of the initial cement components and the reactions of metastable hydration constituents, as well as the mechanical strength and chemical resistance of the hardened cemented matrix.Generally, the study of the precipitation products and their behaviour during cementation and the long-term disposal is extremely difficult because of the system complexity (phase composition and structure) and the lack of the non-destructive analytical methods. The experience accumulated by the countries who advanced nuclear programmes in military and socio-economic fields and which produced important volumes of radioactive wastes, leads us to study some of mineral additives to be used in the conditioning and disposal technology. Is well known that some mineral additives can diminish the leaching rate of the radionuclides in the disposal environment.The studies have the purpose to obtain the most propitious mixture of cement-bentonite and cement-volcanic tuff, which have the mechanical properties similar to the cement paste used for the conditioning of radioactive waste.Taking into account the characteristics of these mineral binders, namely a very good plasticity and capacity of adsorption, which lead at the decrease of porosity, the mixture is planned to be used in the future, at the Radioactive

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

    OpenAIRE

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

    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 i...

  16. 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.

  17. 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.

  18. Advanced technologies of production of cemented carbides and composite materials based on them

    International Nuclear Information System (INIS)

    The paper presents new technological processes of production of W, WC and (Ti, W)C powders, cemented carbides having a controlled carbon content, high-strength nonmagnetic nickel-bonded cemented carbides, cemented carbide-based composites having a wear-resistant antifriction working layer as well as processes of regeneration of cemented carbide waste. It is shown that these technological processes permit radical changes in the production of carbide powders and products of VK, TK, VN and KKhN cemented carbides. The processes of cemented carbide production become ecologically acceptable and free of carbon black, the use of cumbersome mixers is excluded, the power expenditure is reduced and the efficiency of labor increases. It becomes possible to control precisely the carbon content within a two-phase region -carbide-metal. A high wear resistance of parts of friction couples which are lubricated with water, benzine, kerosene, diesel fuel and other low-viscosity liquids, is ensured with increased strength and shock resistance. (author)

  19. 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.

  20. 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

    2016-01-01

    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. PMID:27406467

  1. 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.

  2. 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.

  3. 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.

  4. The Crack Self-healing Properties of Cement-based Material with EVA Heat-melt Adhesive

    Institute of Scientific and Technical Information of China (English)

    YUAN Xiongzhou; SUN Wei; ZUO Xiaobao; LI Hua

    2011-01-01

    An experimental program was carried out to investigate whether EVA(ethylene vinyl acetate copolymer)heat-melt adhesive can potentially act as a self-healing agent in cement-based material.The effects of incorporation of EVA and heating on the properties of mortar were studied.Self-healing capacity of EVA specimens was also verified.The experimental results show that the addition of EVA would not greatly affect original characteristics of the matrix when EVA content was less than 5%;the interface between EVA and cement matrix was well improved after heating,which allows a significant improvement in flexural strength and toughness of specimen;pre-damaged specimens in various degrees(30%,50% and 70%)were effectively repaired by EVA and the repair efficiency all exceeded 100%.

  5. Determination of Mass Attenuation Coefficients for Some Cement Types Used As Building Materials in Turkey

    International Nuclear Information System (INIS)

    This work presents experimental and theoretical mass attenuation coefficient values of six cement types used in building construction in Turkey. The experimental mass attenuation coefficients were measured at 14 different gamma ray energies from 81 to 1332.5 keV by using 109Cd, 57Co, 133Ba, 54Mn, 137Cs, 60Co and 22Na radioactive sources. Measurements were carried out by using gamma spectrometry with a high purity Ge detector with a resolution of 1.9 keV at the 1332.5 keV. The chemical compositions of cement types were analyzed using EDXRF system. Taking into account the elemental compositions of cement types, theoretical mass attenuation coefficients were calculated using XCOM programme

  6. Development of new types of geo cement binding materials based on natural minerals and technology of conditioning of radioactive absorbents (zeolites) and sludge immobilized in geo cement matrix

    International Nuclear Information System (INIS)

    Full text: Recently extensive work on development of decontamination technology of liquid radioactive waste (LRW) of the Armenian Nuclear Plant was carried out at the Yerevan State University within the frame of the project ISTC A-485 ('Efficient Treatment of Radioactive Liquid Waste by Zeolites Modified through Chemical and Radiation Methods '). Clinoptilolite based natural aluminosilicate and other zeolite-based sorbents were used for this purpose. During the work the optimization of the sorbent preparation procedures and of the Cs and Sr removal from radioactive effluents under dynamic and static conditions were implemented. Although a high degree LRW volume reduction (up to 400 - 600 times) was achieved. In the result of mentioned technology application a demand emerges to further management (conditioning) of used zeolites containing absorbed radionuclides which in the case of large-scale usage will be accumulated abundantly at NPPs. The new approach of the project (in the frame of ISTC project A- 1209) is a continuation of the above-mentioned project and it will be devoted to the development of technology of conditioning of spent zeolites which may be qualified as middle-active radioactive waste (MRW). The objectives of the project: the development of the low resource- and energy-saving technology for the conditioning of radioactive waste by immobilization into geo cement matrix materials based on readily available and inexpensive natural and technogenic materials of Armenia, the construction of the corresponding pilot plant and their testing at Armenian NPP

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. Mechanical, electrical and microstructural properties of cement-based materials in conditions of current flow

    NARCIS (Netherlands)

    Susanto, A.; Koleva, D.A.; Copuroglu, O.; Van Beek, C.; Van Breugel, K.

    2012-01-01

    Corrosion in reinforced concrete structures is not only induced by the penetration of aggressive substances (e.g. chlorides and/or CO2) but also influenced by stray currents. Further, the degradation mechanisms in reinforced cement-based systems due to the combined effect of stray current and chlori

  12. ULTRA-LIGHTWEIGHT CEMENT

    International Nuclear Information System (INIS)

    The objective of this project is to develop an improved ultra-lightweigh cement using ultralight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Problems, Task 2: Review Russian Ultra-Lightweight Cement Literature, and Task 3: Test Ultra-Lightweight Cements. Results reported this quarter include a review and summary surface pipe and intermediate casing cementing conditions historically encountered in the US and establishment of average design conditions for ULHS cements. Russian literature concerning development and use of ultra-lightweight cements employing either nitrogen or ULHS was reviewed, and a summary is presented. Quality control testing of materials used to formulate ULHS cements in the laboratory was conducted to establish baseline material performance standards. A testing protocol was developed employing standard procedures as well as procedures tailored to evaluate ULHS. This protocol is presented and discussed. finally, results of initial testing of ULHS cements is presented along with analysis to establish cement performance design criteria to be used during the remainder of the project

  13. Type II supernovae modelisation: neutrinos transport simulation

    International Nuclear Information System (INIS)

    A modelisation of neutrino transport in type II supernovae is presented. The first part is a description of hydrodynamics and radiative processes responsible of supernovae explosions. Macroscopic aspects of these are displayed in part two. Neutrino transport theory and usual numerical methods are also developed. A new technic of coherent scattering of neutrinos on nuclei or free nucleons is proposed in the frame work of the Lorentz bifluid approximation. This method deals with all numerical artifices (flux limiting schemes, closure relationship of Eddington moments) and allows a complete and consistent determination of the time-dependent neutrino distribution function for any value of the opacity, gradient of opacity and for all (relativistic) velocity fields of the diffusive medium. Part three is dedicated to microscopic phenomena (electronic capture, chimical composition, etc) which rule neutrinos emission-absorption mechanisms. The numerical treatments of those are presented, and some applications are useful for their parametrization. Finally, an extension of the method to inelastic scattering on light particules (electrons) is described in view to study neutrinos thermalization mechanism

  14. 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.

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

    OpenAIRE

    Wei-Wen Li; Wei-Ming Ji; Yao-Cheng Wang; Yi Liu; Ruo-Xu Shen; Feng Xing

    2015-01-01

    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...

  16. 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...

  17. 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.

  18. Effect of Relative Humidity and CO2 Concentration on the Properties of Carbonated Reactive MgO Cement Based Materials

    Science.gov (United States)

    Bilan, Yaroslav

    Sustainability of modern concrete industry recently has become an important topic of scientific discussion, and consequently there is an effort to study the potential of the emerging new supplementary cementitious materials. This study has a purpose to investigate the effect of reactive magnesia (reactive MgO) as a replacement for general use (GU) Portland Cements and the effect of environmental factors (CO2 concentrations and relative humidity) on accelerated carbonation curing results. The findings of this study revealed that improvement of physical properties is related directly to the increase in CO2 concentrations and inversely to the increase in relative humidity and also depends much on %MgO in the mixture. The conclusions of this study helped to clarify the effect of variable environmental factors and the material replacement range on carbonation of reactive magnesia concrete materials, as well as providing an assessment of the optimal conditions for the effective usage of the material.

  19. 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。

  20. Sulfate Attack of Cement-Based Material with Limestone Filler Exposed to Different Environments

    Science.gov (United States)

    Gao, Xiaojian; Ma, Baoguo; Yang, Yingzi; Su, Anshuang

    2008-08-01

    Mortar prisms made with OPC cement plus 30% mass of limestone filler were stored in various sulfate solutions at different temperatures for periods of up to 1 year, the visual appearance was inspected at intervals, and the flexural and compressive strength development with immersion time was measured according to the Chinese standard GB/T17671-1999. Samples were selected from the surface of prisms after 1 year immersion and examined by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), laser-raman spectroscopy and scanning electron microscopy (SEM). The results show that MgSO4 solution is more aggressive than Na2SO4 solution, and Mg2+ ions reinforce the thaumasite sulfate attack on the limestone filler cement mortars. The increase of solution temperature accelerates both magnesium attack and sulfate attack on the limestone filler cement mortar, and leads to more deleterious products including gypsum, ettringite and brucite formed on the surface of mortars after 1 year storage in sulfate solutions. Thaumasite forms in the mortars containing limestone filler after exposure to sulfate solutions at both 5 °C and 20 °C. It reveals that the thaumasite form of sulfate attack is not limited to low-temperature conditions.

  1. 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.

  2. New composite grouting materials:Modified urea-formaldehyde resin with cement

    Institute of Scientific and Technical Information of China (English)

    Duan Hongfei; Jiang Zhenquan; Zhu Shuyun; Yao Pu; Sun Qiang

    2012-01-01

    A new composite two component grout comprised of modified urea-formaldehyde resin and cement was formulated to take account of the advantages and disadvantages of both the cement grout and the chemical grout.The new grout is designed for water blocking by reinforcing as well as seepage control by bore grouting.The A component consists of a modified urea-formaldehyde resin A component,some cement,and some water.The B component is an alkaline coagulant.An orthogonal test of four factors at three levels showed that gel time increased with increased water content and with urea-formaldehyde resin content.Gel time decreased at increased levels of alkaline coagulant.The A component of this new composite grout is stable over time.A mixed cross-over test showed that as the volume ratio of A to B increases the gel time falls at first but then increases.The solid strength decreases with increasing levels of the B component.The solid strength increases over time and becomes stable by the 28th day after mixing.The viscosity increases with increasing levels of resin A component.The increase is exponential and may be fit to;μ = 8.162e0.0286x.

  3. 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

  4. 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.

  5. Modelisation et prevision des indices de prix sectoriels.

    OpenAIRE

    Jondeau, E.; Le Bihan, H.; Sedillot, F.

    1999-01-01

    Ce papier presente une modelisation de l'indice des prix francais. L'objectif est de permettre une analyse rapide et detaillee des tendances de court terme de l'inflation ainsi que de realiser des previsions a intervalles rapproches. Les caracteristiques de cet outil sont les suivantes: un petit nombre d'equations, une frequence mensuelle, un detail sectoriel assez fin et la publication d'intervalles de confiance relatifs a la prevision.

  6. Modelisation par elements finis du muscle strie

    Science.gov (United States)

    Leonard, Mathieu

    Ce present projet de recherche a permis. de creer un modele par elements finis du muscle strie humain dans le but d'etudier les mecanismes engendrant les lesions musculaires traumatiques. Ce modele constitue une plate-forme numerique capable de discerner l'influence des proprietes mecaniques des fascias et de la cellule musculaire sur le comportement dynamique du muscle lors d'une contraction excentrique, notamment le module de Young et le module de cisaillement de la couche de tissu conjonctif, l'orientation des fibres de collagene de cette membrane et le coefficient de poisson du muscle. La caracterisation experimentale in vitro de ces parametres pour des vitesses de deformation elevees a partir de muscles stries humains actifs est essentielle pour l'etude de lesions musculaires traumatiques. Le modele numerique developpe est capable de modeliser la contraction musculaire comme une transition de phase de la cellule musculaire par un changement de raideur et de volume a l'aide des lois de comportement de materiau predefinies dans le logiciel LS-DYNA (v971, Livermore Software Technology Corporation, Livermore, CA, USA). Le present projet de recherche introduit donc un phenomene physiologique qui pourrait expliquer des blessures musculaires courantes (crampes, courbatures, claquages, etc.), mais aussi des maladies ou desordres touchant le tissu conjonctif comme les collagenoses et la dystrophie musculaire. La predominance de blessures musculaires lors de contractions excentriques est egalement exposee. Le modele developpe dans ce projet de recherche met ainsi a l'avant-scene le concept de transition de phase ouvrant la porte au developpement de nouvelles technologies pour l'activation musculaire chez les personnes atteintes de paraplegie ou de muscles artificiels compacts pour l'elaboration de protheses ou d'exosquelettes. Mots-cles Muscle strie, lesion musculaire, fascia, contraction excentrique, modele par elements finis, transition de phase

  7. Determination of the effective diffusion coefficient of water through cement-based materials when applying an electrical field

    International Nuclear Information System (INIS)

    The safety and the reliability of a radioactive waste repository rely essentially on the confinement ability of the waste package and the storing structure. In the case of the low-level and intermediate level short-lived radioactive waste, the confinement property, relying on solid matrices made of cement-based materials, is assessed through a natural diffusion test, using a radioactive tracer, from which an effective diffusion coefficient is deduced. The evolution of the materials and more particularly the enhancement of the confinement properties of cement-based materials lead to test duration from a couple of months to a couple of years. The main objective of the present work involves the determination of the effective diffusion coefficient of reference chemical species, in our case the tritiated water, within a shorter time. The theoretical foundation is based on the description of ionic species mass transfer under the effects of an electrical field. With the definitions of a precise experimental protocol and of a formation factor, considered as an intrinsic topological feature of the porous network, it is possible to determine the effective diffusion coefficient of tritiated water for various types of concretes and mortars, and this within a few hours only. The comparison between the developed accelerated test, based on the application of a constant electrical field, and the normed natural diffusion test, using tritiated water, underlined two critical issues. First, omitting the impact of the radioactive decay of tritium during a natural diffusion test, leads to a non-negligible underestimation of the effective diffusion coefficient. Second, maintaining samples in high relative humidity conditions after casting is essential in order to avoid contrasted and unrelated results when performing the electrokinetic tests. Eventually, the validation of the electrokinetics technique, main objective of this work, rests on the assessment of the theoretical hypothesis

  8. Self-healing of Early Age Cracks in Cement-based Materials by Mineralization of Carbonic Anhydrase Microorganism

    Directory of Open Access Journals (Sweden)

    Chunxiang eQian

    2015-11-01

    Full Text Available This research investigated the self-healing potential of early age cracks in cement-based materials incorporating the bacteria which can produce carbonic anhydrase. Cement-based materials specimens were pre-cracked at the age of 7, 14, 28, 60 days to study the repair ability influenced by cracking time, the width of cracks were between 0.1 and 1.0 mm to study the healing rate influenced by width of cracks. The experimental results indicated that the bacteria showed excellent repairing ability to small cracks formed at early age of 7 days, cracks below 0.4 mm was almost completely closed. The repair effect reduced with the increasing of cracking age. Cracks width influenced self-healing effectiveness significantly. The transportation of CO2 and Ca2+ controlled the self-healing process. The computer simulation analyses revealed the self-healing process and mechanism of microbiologically precipitation induced by bacteria and the depth of precipitated CaCO3 could be predicted base on valid Ca2+.

  9. 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.

  10. Microleakage along glass-fibre posts cemented with three different materials after cyclic loading: a pilot study.

    Science.gov (United States)

    Barbić, Marija Rogić; Segović, Sanja; Baraba, Anja; Ribarić, Sonja Pezelj; Katunarić, Marina; Anić, Ivica

    2013-06-01

    The purpose of this in vitro study was to evaluate microleakage along glass-fibre posts cemented with three different cements after cyclic loading. After post-space preparation, fifty obturated root canals were randomly divided into three experimental groups and two control groups. In group 1, Glassix posts were cemented using Harvard cement, in group 2, Fuji PLUS cement was used and in group 3, Variolink II was used for post cementation. The specimens were artificially aged by loading in a special testing machine. Coronal leakage was evaluated using a fluid transport system. Posts cemented with Variolink II, showed significantly higher failure rate after loading, compared to group 1 and 2 (p = 0.009). Comparing microleakage in samples that have not failed, specimens cemented with Variolink II showed significantly less fluid transport than specimens cemented with zinc phosphate and glass ionomer cements (p = 0.04 and p = 0.006, respectively). Variolink II cement exibited significantly less fluid movement compared with Harvard and Fuji PLUS cement. PMID:23940985

  11. Rice husk derived waste materials as partial cement replacement in lightweight concrete Utilização de resíduos derivados da casca de arroz como substitutos parciais do cimento no concreto leve

    OpenAIRE

    Celso Yoji Kawabata; Holmer Savastano Junior; Joana Sousa-Coutinho

    2012-01-01

    In this study rice husk ash (RHA) and broiler bed ash from rice husk (BBA), two agricultural waste materials, have been assessed for use as partial cement replacement materials for application in lightweight concrete. Physical and chemical characteristics of RHA and BBA were first analyzed. Three similar types of lightweight concrete were produced, a control type in which the binder was just CEMI cement (CTL) and two other types with 10% cement replacement with, respectively, RHA and BBA. All...

  12. Effect of Cement and Compaction on the Physicochemical Behavior of a Material in the Region of Sidi Bel Abbes

    Directory of Open Access Journals (Sweden)

    N. S. Ikhlef

    2014-08-01

    Full Text Available Soil treatment describes the procedure under which a soil acquires certain characteristics that did not originally have. This paper is focused in the field of road earthworks and the treatment of a material found in the region of Sidi Bel Abbes, Algeria. This material has poor characteristics that do not meet the standards used in road geotechnics. To remedy this, firstly, the Proctor Standard characteristics of this material were improved using mechanical treatment that increased the compaction energy. Then a chemical treatment was employed, adding some cement dosages, and results show that the material classified in the A1h class, for an increased maximum dry density and a reduction in water content. A comparative study is made on the optimal properties of the material between the two modes of treatment. On the other hand, after treatment, one finds a decrease in the plasticity index and the methylene blue value. This material exhibits a change of class. Therefore, soil class CL turned into a soil class CL-ML (silt of low plasticity. This observation allows the material to be used as backfill or subgrade.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. Comparison of sealing ability of bioactive bone cement, mineral trioxide aggregate and Super EBA as furcation repair materials: A dye extraction study

    Directory of Open Access Journals (Sweden)

    Janani Balachandran

    2013-01-01

    Settings and Design: In vitro, dye extraction study. Materials and Methods: Forty mandibular molars were randomly divided according to the material used to repair perforation: Group I-MTA, Group II-bioactive bone cement, Group III-Super EBA, Group IV-Control (furcation left unrepaired. All samples were subject to ortho grade and retrograde methylene blue dye challenge followed by dye extraction with 65% nitric acid. Samples were then analyzed using Ultra violet (UV Visible Spectrophotometer. Statistical Analysis Used: One way analysis of variance (ANOVA, Tukey-Kramer Multiple Comparisons Test. Results: MTA and bioactive bone cement showed almost similar and lower absorbance values in comparison to Super EBA. Conclusions: Bioactive bone cement provi ded an excellent seal for furcal perforation repair and at the same time it provided comfortable handling properties, which could overcome the potential disadvantages as faced with MTA.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. A study on the technology for reducing cement-type materials used for tunnel supports at high-level radioactive waste disposal sites (Joint research)

    International Nuclear Information System (INIS)

    Cement-type materials that are used for supports or grouting at high-level radioactive waste disposal facilities leach into the groundwater and create a highly alkaline environment. Of concern in highly alkaline environments are the alteration of bentonite used as buffers or backfill materials, and of surrounding rock mass, and the increased uncertainty regarding the provision of performance of the disposal system over a long period of time. From such a background, The Japan Atomic Energy Agency and Shimizu Corporation carried out a Joint Research aimed for technology development to reduce the use of cement-type materials at high-level radioactive waste disposal facilities as much as possible. The Japan Atomic Energy Agency has been conducting research and development of low alkalinity cement with a view to controlling the effects of high alkalinity, and focusing on its use as support materials. In the meantime, Shimizu Corporation has been developing methods for constructing tunnels using the minimum quantities of cement-type support materials and suggesting the possibility of realization of support structures using greatly reduced quantities of cement. In this study, the quantities of cement used for supports were first presented under the geological condition (soft or hard rock) by the method of waste disposal (vertical or horizontal) described in the secondary report on geological disposal of high-level radioactive waste. Then, alternative supports mainly composed of rock and bentonite were proposed to ensure long-term provision of the performance of the disposal system. The mechanical characteristic values concerning the strength and deformation properties of the alternative supports and backfill materials (for filling the gap between the tunnel wall and the segmental ring) were examined. The supports were designed based on the physical properties of rock mass and earth pressure described in the secondary report, and on the physical property values of the

  7. 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.

  8. 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).

  9. Surface fractal dimension: An indicator to characterize the microstructure of cement-based porous materials

    Science.gov (United States)

    Zeng, Qiang; Luo, Mingyong; Pang, Xiaoyun; Li, Le; Li, Kefei

    2013-10-01

    This study investigates the surface fractal dimensions (SFDs) of pore structure of cement pastes and mortars with/without ground granulated blast-furnace slag (GGBS) incorporated into binder. The samples were subject to water curing and sealed curing. The fractal dimensions of samples are determined by Zhang’s model (Ind Eng Chem Res, 34 (1995):1383-1386) on the basis of mercury intrusion porosimetry (MIP) data. The results confirm the scale-dependent property of fractal dimension of pore structures and the micro-fractal, transition and macro-fractal regions are identified for all samples. The upper pore size range for micro-fractal regions is around 30 nm, the transition regions cover 0.5-2 magnitude orders of pore size and macro fractal regions cover 1.5-3 magnitude orders. Both curing conditions and GGBS in binder have impact on the fractal properties of pore structure, and samples incorporating GGBS have substantially larger values for micro-fractal regions.

  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. ULTRA-LIGHTWEIGHT CEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fred Sabins

    2003-01-31

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). This report discusses testing that was performed for analyzing the alkali-silica reactivity of ULHS in cement slurries. DOE joined the Materials Management Service (MMS)-sponsored joint industry project ''Long-Term Integrity of Deepwater Cement under Stress/Compaction Conditions.'' Results of the project contained in two progress reports are also presented in this report.

  12. The characterisation, improvement and modelling aspects of Frost Salt Scaling of Cement-Based Materials with a High Slag Content

    NARCIS (Netherlands)

    Copuroglu, O.

    2006-01-01

    Blast furnace slag cement concrete is used extensively in a number of countries. In comparison with OPC, it is particularly well known for its excellent performance in marine environments. One dis-advantage of slag cement is its vulnerability to scaling under the combined load of freezing-thawing an

  13. 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

  14. 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.

  15. Contribution to the modeling of elaborate cement barriers behaviour with respect to radioelements migration by the study of ancient analogue materials

    International Nuclear Information System (INIS)

    The durability of cement matrices and their capacity of radioelements retention are determining factors for their use as elaborate barriers in radioactive waste disposal facilities. This study focusses on the observation of concretes in real situation of alteration or in contact with radioelements for predictive modelling. Two materials have been selected. One is a concrete from a gallery wall of the Margnac uranium mine (Cogema, France) submitted to uranium-rich infiltration waters. The alteration concentrates in two characteristic successive zones: the first is composed of calcium depleted and aluminum enriched calcite and calcium hydro-silicates and the second, between the first zone and the sound matrix, is characterized by a self-filling in process due to massive ettringite precipitation induced by sulfate ions transport. Uranium migration depends closely on the fissures and porosity of the cement matrix. The second series of samples correspond to 2000 years old archaeological cements from Pompei (Italy) made of volcanic ashes and carrying uranium traces. These samples were submitted to burying and alteration is characterized by a carbonation of the cement matrix. The mineralogy is closed to the one defined in the first alteration zone of the uranium mine concrete. Both studies demonstrate that the presence of carbonate ions in the percolation water plays a major role in the alteration process. Sulfate reactions must be considered too and tend to diminish the materials porosity and to increase the delay in radionuclides migration processes. (J.S.). 131 refs., 92 figs., 55 tabs., 51 photos., 15 appends

  16. 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.

  17. Cementing porcelain-fused-to-metal crowns.

    Science.gov (United States)

    Vadachkoria, D

    2009-12-01

    The clinical success of fixed prosthodontic restorations can be complex and involve multifaceted procedures. Preparation design, oral hygiene/micro flora, mechanical forces, and restorative materials are only a few of the factors which contribute to overall success. One key factor to success is choosing the proper cement. Popular use of cements for PFM crowns has shifted from zinc phosphate and glass ionomer cements to resin-reinforced glass ionomer, or RRGI, cements. This change has been rapid and profound. Dental cements have always been less than ideal materials, but this is shift to the relatively new RRGI category justified. Resin-reinforced glass ionomer (RRGI) cements appear to be better than zinc phosphate and glass ionomer cements when placing porcelain-to-metal crowns. RRGI cements, such as RelyX Luting, Fuji Plus and Vitremer Luting Cement, satisfy more of the ideal characteristics of PFM cementation than any other previous cement. Expansion of all three cements has not caused any apparent problems with the cements when used with PFM or metal crowns, but these cements, however, should be avoided when cementing all-ceramic crowns. PMID:20090144

  18. 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

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

    OpenAIRE

    Wu, Min; Johannesson, Björn; Geiker, Mette Rica

    2014-01-01

    Porestrukturen er en af de vigtigste karakteristika ved cement baserede materialer. Dette PhD studium har fokuseret på brugen af lav (mikro-)temperatur calorimetri (LTC) og en fugt fikserings metode til bestemmelse af porestrukturen i cement baserede materialer, specielt på nano-skala. Der er specielt lagt vægt på undersøgelser af faktorer, som har indflydelse på analysen af målte data og brugen af LTC til at karakterisere porestrukturen i cement baserede materialer. Fugt fikserings metoden b...

  20. 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).

  1. 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

  2. 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

  3. Microscale Investigation of Arsenic Distribution and Species in Cement Product from Cement Kiln Coprocessing Wastes

    OpenAIRE

    Yufei Yang; Jingchuan Xue; Qifei Huang

    2013-01-01

    To improve the understanding of the immobilization mechanism and the leaching risk of Arsenic (As) in the cement product from coprocessing wastes using cement kiln, distribution and species of As in cement product were determined by microscale investigation methods, including electron probe microanalysis (EPMA) and X-ray absorption spectroscopy. In this study, sodium arsenate crystals (Na3AsO412H2O) were mixed with cement production raw materials and calcined to produce cement clinker. Then, ...

  4. Present and future of glass-ionomers and calcium-silicate cements as bioactive materials in dentistry: Biophotonics-based interfacial analyses in health and disease

    OpenAIRE

    Watson, Timothy F; Atmeh, Amre R.; Sajini, Shara; Cook, Richard J.; Festy, Frederic

    2014-01-01

    Objective Since their introduction, calcium silicate cements have primarily found use as endodontic sealers, due to long setting times. While similar in chemistry, recent variations such as constituent proportions, purities and manufacturing processes mandate a critical understanding of service behavior differences of the new coronal restorative material variants. Of particular relevance to minimally invasive philosophies is the potential for ion supply, from initial hydration to mature set i...

  5. 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。

  6. CEMENT SLURRIES FOR GEOTHERMAL WELLS CEMENTING

    OpenAIRE

    Nediljka Gaurina-Međimurec; Davorin Matanović; Gracijan Krklec

    1994-01-01

    During a well cementing special place belongs to the cement slurry design. To ensure the best quality of cementing, a thorough understanding of well parameters is essential, as well as behaviour of cement slurry (especially at high temperatures) and application of proven cementing techniques. Many cement jobs fail because of bad job planning. Well cementing without regarding what should be accomplished, can lead to well problems (channels in the cement, unwanted water, gas or fluid production...

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

    OpenAIRE

    Ashraf Fadiel; Fouad Al Rifaie; Taher Abu-Lebdeh; Ellie Fini

    2014-01-01

    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 exp...

  8. 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

    A novel two-solution poly(methyl methacrylate) bone cement was developed as an alternative to powder/liquid cements, which are used clinically for the fixation of total joint replacements. This material polymerizes via a free radical mechanism, initiated by the redox reaction of benzoyl peroxide (BPO) and N,N dimethyl-p-toluidine (DMPT). The two-solution concept is advantageous over powder/liquid formulations because it minimizes sources of porosity, produces a homogeneous microstructure, simplifies the mixing and delivery process, and reduces the dependence of material properties on surgical techniques. Experiments were performed to determine the effect of initiation chemistry on the material properties and polymerization kinetics of twelve cement compositions. Select material properties were also evaluated with respect to polymer/monomer ratio and initial polymer molecular weight. The results confirm the hypothesis that initiation chemistry affects material properties via the polymerization kinetics and resulting microstructural properties. The exotherm, setting time, flexural mechanical properties, fracture toughness, fatigue behavior, and residual monomer were evaluated, with respect to initiation chemistry. The flexural strength, modulus, and exotherm were maximized, while the residual monomer was minimized at a BPO:DMPT molar ratio of 1:1. High DMPT concentrations resulted in sub-optimal properties, with short setting times and reduced ductility, fracture toughness, and fatigue strength. Initial polymer molecular weight had no significant effect on the material properties. Polymer conversion and free radical concentration were measured by infrared (FTIR) and electron paramagnetic resonance (EPR) spectroscopy. These data were used to calculate the polymerization reaction rates and kinetic rate constants for each composition. Stoichiometric concentrations of BPO and DMPT maximized the radical concentration and conversion. The BPO and DMPT concentrations

  9. Manufacture and properties of fluoride cement

    Science.gov (United States)

    Malata-Chirwa, Charles David

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

  10. The application research of lightweight foam cement in the grouting materials%轻质泡沫水泥注浆材料的应用研究

    Institute of Scientific and Technical Information of China (English)

    胡焕校; 罗玮; 唐良智; 彭春雷; 夏凌云

    2011-01-01

    A preliminary study was made that inflatable foam cement slurry was used as grouting material by employing orthogonal experiment. The indicators such as specific density, viscosity, syneresis rate, stone density and stone rate of inflatable foam cement slurry had been tested, which depended on the different foaming and foam stabilizing agent by the orthogonal experimental method. The experimental results show that it can be used as grouting material for a variety of anti-seepage grouting works. The reasonable parameters and ratio were given by considering stone density and stone rate of inflatable foam cement slurry.%用不同的发泡剂和稳泡剂,采用正交实验,对轻质泡沫水泥浆液作为注浆材料作了初步研究,测试了轻质泡沫水泥浆液的比重、粘度、析水率、结石体密度和结石率等指标,根据实验结果进行了分析研究,从结石体密度和结石体的结石率考虑优选出一种作为注浆材料用于充填防渗注浆的轻质泡沫水泥浆液的合理参数配比.

  11. Comparison of push-out bond strength of mineral trioxide aggregate and calcium enriched mixture cement as root end filling materials

    Directory of Open Access Journals (Sweden)

    Alireza Adl

    2014-01-01

    Full Text Available Background: The purpose of this study was to compare the push-out bond strength of mineral trioxide aggregate (MTA and calcium enriched mixture (CEM as root end filling materials. Materials and Methods: A total of 40 root dentin slices (1 ± 0.2 mm were prepared from freshly extracted human maxillary central teeth and their lumens were enlarged to 1.3 mm. The slices were randomly divided into two groups (n = 20. MTA and CEM cement were mixed according to manufacturer′s instruction and introduced into the lumens. The specimens were wrapped in pieces of wet gauze soaked in distilled water and incubated at 37°C for 3 days. The push-out bond strength was measured using a universal testing machine. The slices were then examined under a light microscope at ×10 magnification to determine the nature of bond failure. The data were analyzed using Mann-Whitney test (P < 0.001. Results: The mean push-out bond strength for CEM cement and MTA were 1.68 ± 0.9 and 5.94 ± 3.99 respectively. The difference was statistically significant (P < 0.001. The bond failure was predominantly of adhesive type in MTA group and cohesive type in CEM group. Conclusion: CEM cement showed significantly lower bond strength to the dentinal wall compared to MTA.

  12. The cement recycling of the earthquake disaster debris by Hachinohe Cement Co., Ltd

    International Nuclear Information System (INIS)

    A tremendous quantity of earthquake disaster debris and tsunami sediment was resulted by the Great East Japan Earthquake on March 11, 2011. Hachinohe Cement Co., Ltd., a Sumitomo Osaka Cement subsidiary, was the first cement industry company to receive and process such waste materials outside of their usual prefecture area, while the company is performing their treatment and recycling services locally in Hachinohe City and Aomori Prefecture. This report provides an explanation about the recycling mechanism of waste materials and by-products in cement manufacturing process, and introduces an example of actual achievements for the disaster debris treatment by utilizing the cement recycling technologies at the Hachinohe Cement Plant. (author)

  13. 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.

  14. Solid phase characterization and gas transfers through unsaturated porous media: experimental study and modeling applied diffusion of hydrogen through cement-based materials

    International Nuclear Information System (INIS)

    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)

  15. Effect of an organic additive on the rheology of an aluminous cement paste and consequences on the densification of the hardened material

    Science.gov (United States)

    El Hafiane, Y.; Smith, A.; Bonnet, J. P.; Tanouti, B.

    2005-03-01

    The material used in the present work is Secar 71 (Lafarge) mixed with water containing an organic additive (acetic acid noted HOAc). The rheological behavior of these pastes is studied. The best dispersion is obtained when the mass content of the additive with respect to the cement is equal to 0.5%. The microstructural characterizations of samples aged 4 days at 20° C and 95 % relative humidity reveal a significant increase in the density and a reduction in porosity for very small percentages of additive. The remarkable effect of the acetic acid on the microstructure of hardened material is correlated with its good dispersing action.

  16. Effects of air abrasion with alumina or glass beads on surface characteristics of CAD/CAM composite materials and the bond strength of resin cements

    Directory of Open Access Journals (Sweden)

    ARAO Nobuaki

    2015-12-01

    Full Text Available ABSTRACT Objective The study aimed to evaluate effects of air abrasion with alumina or glass beads on bond strengths of resin cements to CAD/CAM composite materials. Material and Methods CAD/CAM composite block materials [Cerasmart (CS and Block HC (BHC] were pretreated as follows: (a no treatment (None, (b application of a ceramic primer (CP, (c alumina-blasting at 0.2 MPa (AB, (d AB followed by CP (AB+CP, and (e glass-beads blasting at 0.4 MPa (GBB followed by CP (GBB+CP. The composite specimens were bonded to resin composite disks using resin cements [G-CEM Cerasmart (GCCS and ResiCem (RC]. The bond strengths after 24 h (TC 0 and after thermal cycling (TC 10,000 at 4–60°C were measured by shear tests. Three-way ANOVA and the Tukey compromise post hoc tests were used to analyze statistically significant differences between groups (α=0.05. Results For both CAD/CAM composite materials, the None group exhibited a significant decrease in bond strength after TC 10,000 (p0.05. The AB+CP group showed a significantly higher bond strength after TC 10,000 than did the AB group for RC (p<0.05, but not for GCCS. The GBB+CP group showed the highest bond strength for both thermal cyclings (p<0.05. Conclusions Air abrasion with glass beads was more effective in increasing bond durability between the resin cements and CAD/CAM composite materials than was using an alumina powder and a CP.

  17. Micromechanical modelling of heterogeneous materials in transient conditions: contributions for the study of the ageing of structural components under service; Modelisation micromecanique des materiaux heterogenes en regimes transitoires: contributions en vue de l'etude du vieillissement des structures en service

    Energy Technology Data Exchange (ETDEWEB)

    Masson, R.

    2010-12-20

    considering the particular situation where regions of the representative volume element have ill-defined mechanical properties. In the linear elastic case, new bounds for the effective behaviour are derived by marrying the structural analysis and a variational approach. This last work opens on important prospects for further works: more tightened bounds, nonlinear behaviours,... Considering homogenisation methods, further works are precisely defined, in particular for polycrystalline materials. In that situation, the field of investigation widens clearly (Fatigue, Large strains,...) thanks to the internal variables formulation proposed. Lastly, the simulation of irradiation effects constitutes the third topic of interest for the years to come, the general objective being to better predict the effects of the swelling strains induced by irradiation on the behaviour of structural components under service. (author) [French] La modelisation du comportement mecanique des materiaux de structure se nourrit de plus en plus de parametres microstructuraux. Dans ce cadre, les methodes d'homogeneisation presentent l'avantage de fournir des methodes deductives qui, a partir des proprietes et de la repartition spatiale des heterogeneites, deduisent les proprietes effectives du materiau considere. Neanmoins de nombreuses applications soulevent encore des difficultes. C'est en particulier le cas des materiaux de structure presentant un comportement elasto-viscoplastique et soumis a un trajet de chargement non monotone et non isotherme. Progresser sur le traitement par homogeneisation de ces situations concretes constitue precisement le fil conducteur des differentes contributions presentees dans ce memoire d'HDR. Dans le cas elastique lineaire, de nouvelles expressions pour le calcul du tenseur d'Eshelby sont tout d'abord etablies afin d'ameliorer l'efficacite des methodes d'homogeneisation habituellement proposees. Toujours pour des comportements

  18. A contribution to the physical and chemical model of long-lived radioactive wastes by clayey materials; Contribution a la modelisation physico-chimique de la retention de radioelements a vie longue par des materiaux argileux

    Energy Technology Data Exchange (ETDEWEB)

    Gorgeon, L.

    1994-11-25

    This work deals with the high-level and long-lived radioactive wastes confinement which come from the irradiated fuels reprocessing. These wastes are generally coated in a deep geological structure confinement matrix. The radiation protection of a such storage requires that the coating matrix, the technological barriers which separate the storage and the geological medium and the reception rock does not let the radioactive wastes pass. The materials used in this work for the confinement studies are clayey minerals and the retention mechanisms studies are realized on cesium 135, neptunium 237, americium 241 and uranium 233. The first part of this thesis concerns the clayey minerals retention properties towards ions in aqueous solutions. More particularly the relations between these properties and the chemical structure of these solids are investigated. In the second part are presented the experimental works which have allowed to specify the intrinsic characteristics of the studied minerals. Indeed the knowledge of these parameters is essential to quantitatively explain the results of the radionuclides retention. The adsorption mechanisms are described in a third part. (O.L.). 112 refs., 59 figs., 51 tabs.

  19. 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.

  20. 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......−liquid reactions are discussed, as are the influences of particles sizes on clinker phase formation. Furthermore, a mechanism for clinker phase formation in an industrial rotary kiln reactor is outlined....

  1. 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

  2. A Comprehensive Study of Osteogenic Calcium Phosphate Silicate Cement: Material Characterization and In Vitro/In Vivo Testing.

    Science.gov (United States)

    Gong, Tianxing; Wang, Zhiqin; Zhang, Yixi; Zhang, Yubiao; Hou, Mingxiao; Liu, Xinwei; Wang, Yu; Zhao, Lejun; Ruse, N Dorin; Troczynski, Tom; Häfeli, Urs O

    2016-02-18

    Vertebral compression fractures can be successfully restored by injectable bone cements. Here the as-yet unexplored in vitro cytotoxicity, in vivo biodegradation, and osteoconductivity of a new calcium phosphate silicate cements (CPSC) are studied, where monocalcium phosphate (MCP; 5, 10, and 15 wt%) is added to calcium silicate cement (CSC). Setting rate and compressive strength of CPSC decrease with the addition of MCP. The crystallinity, microstructure, and porosity of hardened CPSC are evaluated by X-ray diffractometer, Fourier transform infrared spectroscopy, and microcomputed tomography (CT). It is found that MCP reacts with calcium hydroxide, one of CSC hydration products, to precipitate apatite. While the reaction accelerates the hydration of CSC, the formation of calcium silicate hydrate gel is disturbed and highly porous microstructures form, resulting in weaker compressive strength. In vitro studies demonstrate that CPSC is noncytotoxic to osteoblast cells and promotes their proliferation. In the rabbit tibia implantation model, clinical X-ray and CT scans demonstrate that CPSC biodegrades slower and osseointegrates better than clinically used calcium phosphate cement (CPC). Histological studies demonstrate that CPSC is osteoconductive and induces higher bone formation than CPC, a finding that might warrant future clinical studies. PMID:26677175

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. Density and water content corrections in the gamma count rate of a PGNAA system for cement raw material analysis using the MCNP Code

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Carlos; Salgado, Jose [Nuclear and Technological Institute, Sacavem (Portugal); Leitao, Francisco [Technical Centre, Cimpor, Lisbon (Portugal)

    1998-05-11

    A MCNP simulation study for a prompt gamma neutron activation analysis system for on-line characterisation of cement raw materials has been carried out. A neutron source is located below a conveyor belt. Two detector banks were used: a lower bank positioned symmetrically around the source to detect {gamma}-rays emitted downwards; an upper bank detects the radiation emitted upwards. The count rate of both detector banks for a given composition depends on the bulk density and water content. This paper reports a few corrections which linearise the dependence of the corrected count rate on the mass content.

  8. Effect of temporary cements on the shear bond strength of luting cements

    Directory of Open Access Journals (Sweden)

    Marco Fiori-Júnior

    2010-02-01

    Full Text Available OBJECTIVE: The purpose of this study was to evaluate, by shear bond strength (SBS testing, the influence of different types of temporary cements on the final cementation using conventional and self-etching resin-based luting cements. Material and Methods: Forty human teeth divided in two halves were assigned to 8 groups (n=10: I and V (no temporary cementation; II and VI: Ca(OH2-based cement; III and VII: zinc oxide (ZO-based cement; IV and VIII: ZO-eugenol (ZOE-based cement. Final cementation was done with RelyX ARC cement (groups I to IV and RelyX Unicem cement (groups V to VIII. Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. RESULTS: Means were (MPa: I - 3.80 (±1.481; II - 5.24 (±2.297; III - 6.98 (±1.885; IV - 6.54 (±1.459; V - 5.22 (±2.465; VI - 4.48 (±1.705; VII - 6.29 (±2.280; VIII - 2.47 (±2.076. Comparison of the groups that had the same temporary cementation (Groups II and VI; III and VII; IV and VIII showed statistically significant difference (p0.05 for the different luting cements (RelyX TM ARC and RelyX TM Unicem. The groups that had no temporary cementation (Groups I and V did not differ significantly from each other either (p>0.05. CONCLUSION: When temporary cementation was done with ZO- or ZOE-based cements and final cementation was done with RelyX ARC, there was an increase in the SBS compared to the control. In the groups cemented with RelyX Unicem, however, the use of a ZOE-based temporary cement affected negatively the SBS of the luting agent used for final cementation.

  9. REMOVAL OF SOLUBLE CR(VI) IN CEMENTS BY FERROUS SULPHATE MONOHYDRATE, SOLID LIGNIN AND OTHER MATERIALS

    OpenAIRE

    T. TUNÇ; K. ESEN; DONAT, R; Erdem, E.

    2011-01-01

    Various reducing agents such as ferrous sulphate heptahydrate (HH) and monohydrate (MH), solid lignin (SL), Na2S2O4, NaHSO3, SnCl2·2H2O, N2H4·H2O and FeS are used to reduce Cr(VI) contents of three types of cements under 2 mg/L, as it is requested by European Parliament Standards. Optimum conversion temperature of HH to MH was found as 130°C, for 20 min., by thermal analysis. Minimum amounts of various agents to be used as additives in cements to reduce Cr(VI) contents under the standard valu...

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

    OpenAIRE

    Baoguo Ma; Hainan Li; Junpeng Mei; Xiangguo Li; Fangjie Chen

    2015-01-01

    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 c...

  11. Engineering properties of cement mortar with pond ash in South Korea as construction materials: from waste to concrete

    Science.gov (United States)

    Jung, Sang; Kwon, Seung-Jun

    2013-09-01

    Among the wastes from coal combustion product, only fly ash is widely used for mineral mixture in concrete for its various advantages. However the other wastes including bottom ash, so called PA (pond ash) are limitedly reused for reclamation. In this paper, the engineering properties of domestic pond ash which has been used for reclamation are experimentally studied. For this, two reclamation sites (DH and TA) in South Korea are selected, and two domestic PAs are obtained. Cement mortar with two different w/c (water to cement) ratios and 3 different replacement ratios (0%, 30%, and 60%) of sand are prepared for the tests. For workability and physical properties of PA cement mortar, several tests like flow, setting time, and compressive strength are evaluated. Several durability tests including porosity measuring, freezing and thawing, chloride migration, and accelerated carbonation are also performed. Through the tests, PA (especially from DH area) in surface saturated condition is evaluated to have internal curing action which leads to reasonable strength development and durability performances. The results show a potential applicability of PA to concrete aggregate, which can reduce consuming natural resources and lead to active reutilization of coal product waste.

  12. 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

  13. Cements in radioactive waste management. Characterization requirements of cement products for acceptance and quality assurance purposes

    International Nuclear Information System (INIS)

    Cementitious materials are used as immobilizing matrices for low (LLW) and medium-level wastes (MLW) and are also components of the construction materials in the secondary barriers and the repositories. This report has concerned itself with a critical assessment of the quality assurance aspects of the immobilization and disposal of MLW and LLW cemented wastes. This report has collated the existing knowledge of the use and potential of cementitious materials in radioactive waste immobilization and highlighted the physico-chemical parameters. Subject areas include an assessment of immobilization objectives and cement as a durable material, waste stream and matrix characterization, quality assurance concepts, nature of cement-based systems, chemistry and modelling of cement hydration, role and effect of blending agents, radwaste-cement interaction, assessment of durability, degradative and radiolytic processes in cements and the behaviour of cement-based matrices and their near-field interactions with the environment and the repository conditions

  14. Mineralogical composition and phase-to-phase relationships in natural hydraulic lime and/or natural cement - raw materials and burnt products revealed by scanning electron microscopy

    Science.gov (United States)

    Kozlovcev, Petr; Přikryl, Richard; Racek, Martin; Přikrylová, Jiřina

    2016-04-01

    In contrast to modern process of production of cement clinker, traditional burning of natural hydraulic lime below sintering temperature relied on the formation of new phases from ion migration between neighbouring mineral grains composing raw material. The importance of the mineralogical composition and spatial distribution of rock-forming minerals in impure limestones used as a raw material for natural hydraulic lime presents not well explored issue in the scientific literature. To fill this gap, the recent study focuses in detailed analysis of experimentally burnt impure limestones (mostly from Barrandian area, Bohemian Massif). The phase changes were documented by optical microscopy, X-ray diffraction, and scanning electron microscopy with an energy dispersive spectrometer (SEM-EDS) coupled with x-ray elemental mapping. The latest allowed for visualization of distribution of elements within raw materials and burnt products. SEM/EDS study brought valuable data on the presence of transitional and/or minor phases, which were poorly detectable by other methods.

  15. Fly and bottom ashes from biomass combustion as cement replacing components in mortars production: rheological behaviour of the pastes and materials compression strength.

    Science.gov (United States)

    Maschio, Stefano; Tonello, Gabriele; Piani, Luciano; Furlani, Erika

    2011-10-01

    In the present research mortar pastes obtained by replacing a commercial cement with the equivalent mass of 5, 10, 20 and 30 wt.% of fly ash or bottom ash from fir chips combustion, were prepared and rheologically characterized. It was observed that the presence of ash modifies their rheological behaviour with respect to the reference blend due to the presence, in the ashes, of KCl and K2SO4 which cause precipitation of gypsum and portlandite during the first hydration stages of the pastes. Hydrated materials containing 5 wt.% of ash display compression strength and absorption at 28 d of same magnitude as the reference composition; conversely, progressive increase of ash cause a continuous decline of materials performances. Conversely, samples tested after 180 d display a marked decline of compression strength, as a consequence of potassium elution and consequent alkali-silica reaction against materials under curing.

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

    OpenAIRE

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

    2006-01-01

    For reasons of market demand and Portland cement production,the manufacture of cements with two or more separately ground additions to produce customized cements is becoming common practice.When pozzolan or slag content in this type of cements is high, however, the initial strength of the resulting product may be adversely impacted. This problem can be minimized by activating one or both of the replacement materials. The present study analyzes the effect of Portland cement additions such as p...

  17. 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.

  18. Effect of cements on fracture resistance of monolithic zirconia crowns

    OpenAIRE

    Nakamura, Keisuke; Mouhat, Mathieu; Nergård, John Magnus; Lægreid, Solveig Jenssen; Kanno, Taro; Milleding, Percy; Örtengren, Ulf

    2016-01-01

    Abstract Objectives The present study investigated the effect of cements on fracture resistance of monolithic zirconia crowns in relation to their compressive strength. Materials and methods Four different cements were tested: zinc phosphate cement (ZPC), glass-ionomer cement (GIC), self-adhesive resin-based cement (SRC) and resin-based cement (RC). RC was used in both dual cure mode (RC-D) and chemical cure mode (RC-C). First, the compressive strength of each cement was tested according to a...

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

    Directory of Open Access Journals (Sweden)

    Jagmeet Singh

    2016-04-01

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

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

    International Nuclear Information System (INIS)

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

  1. 掺加纳米材料水泥土无侧限抗压强度试验研究∗%Research on Unconfined Compressive Strength of Soil Cement with Nano Structured Materials

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    把纳米SiO2、纳米Al2 O3和纳米蒙脱土3种纳米材料加入普通水泥土中,制备掺加纳米材料的水泥土。通过室内无侧限抗压强度试验,研究不同纳米材料及其掺量、龄期、水泥掺量、水胶比对添加纳米材料水泥土无侧限抗压强度的影响,为添加纳米材料水泥土的进一步研究及其在实际工程中的应用提供了方向。%Nano⁃SiO2 , nano⁃Al2 O3 and nano⁃montmorillonite are added into plain soil cement as the admixtures. The influence of various factors including the variety and content of nano structured materials, the age, the content of cement, the water⁃to⁃binder ( the sum of cement and nano structured materials) ratio on the unconfined compressive strength of soil cement is studied. The direction of the further study and the practical application of soil cement with nano structured materials is provided.

  2. 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.

  3. 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.

  4. 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.

  5. Evaluation of the Luting Cement Space for Provisional Restoration by using Various Coats of Die Spacer Materials-An Invitro Study

    Science.gov (United States)

    Siddineni, Krishna Chaitanya; Jyothula, Ravi Rakesh Dev; Gade, Phani Krishna; Bhupathi, Deepthi; Kondaka, Sudheer; Hussain, Zakir; Paluri, Geetha Bhavani

    2014-01-01

    Aim: The present study was to evaluate the space provided for the temporary luting cement, after the application of various coats of die spacers, during the fabrication of provisional crowns and bridges. Materials and Methods: A total of 50 specimens of dental stone with provisional crowns on all these samples were prepared and were divided into five groups based on the application of various coats of different die spacers. Later these specimens were sectioned buccolingually and were observed using a stereomicroscope under 100X magnification. The images thus obtained were evaluated and noted for the amount of space between the inner surface of the provisional crown and the specimens at five different locations using Image Pro 6.0 Express software and the values were subjected to one-way ANOVA test, and unpaired t-test. Results: There was a significant increase of luting space thickness with various die spacer applications than the specimens of control group. Conclusion: Specimens of double coat applications of silver and gold die spacers showed higher luting cement space than the separating media application specimens. PMID:25386515

  6. Ruedersdorf cement works substitutes raw material and fuel by means of a circulating fluidised bed; Roh- und Brennstoffsubstitution mit einer Zirkulierenden Wirbelschicht im Zementwerk Ruedersdorf

    Energy Technology Data Exchange (ETDEWEB)

    Scur, P. [Ruedersdorfer Zement GmbH, Ruedersdorf (Germany)

    1998-09-01

    The purpose of the present paper is to point out the great potential the cement industry holds for the utilisation of waste materials. There are meanwhile sufficient studies and measuring results to demonstrate the environmental acceptability of the processes and products involved. The solution found for Ruedersdorf cement kiln of using a circulating a fluidised bed for waste utilisation is a good example of the potential still available for conserving natural resources and landfill area. Efficient industrial applications of this kind should become a future mainstay of the waste industry. [Deutsch] In dem vorliegenden Beitrag sollte gezeigt werden, dass die Zementindustrie ueber ein hohes Potential zur thermischen und stofflichen Verwertung von Abfallstoffen verfuegt. Es liegen ausreichende Untersuchungen und konkrete Messergebnisse vor, mit denen die Umweltvertraeglichkeit von Prozess und Produkt nachgewiesen werden kann. Die Loesung zur Abfallverwertung an der Ruedersdorfer Zementofenanlage mit Hilfe einer Zirkulierenden Wirbelschicht ist ein Beispiel fuer die Reserven zur Schonung natuerlicher Ressourcen und zur Einsparung von Deponieraeumen. Derartige sinnvolle industrielle Einsatzmoeglichkeiten sollten ein wichtiges Standbein fuer die zukuenftige Abfallwirtschaft sein. (orig.)

  7. Evaluation of red mud as pozzolanic material in replacement of cement for production of mortars; Avaliacao da lama vermelha como material pozolanico em substituicao ao cimento para producao de argamassas

    Energy Technology Data Exchange (ETDEWEB)

    Manfroi, E.P.; Cheriaf, M.; Rocha, J.C., E-mail: elizmanfroi@yahoo.com.b, E-mail: malik@valores.ufsc.b [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Engenharia Civil

    2010-07-01

    Red mud is a by-product of the alkaline extraction of aluminum from the bauxite and represents a renewed environmental problem due the significant annual throughput by the plants. In the present work, the pozzolanic properties of Brazilian red mud fired at 600, 700, 800 and 900 deg C were investigated by monitoring lime consumption using DTA analysis and Brazilian standard methodology NBR 5772 (1992). Products and kinetics of hydration were determined in cement pastes produced with 5 and 15% red mud using x-ray diffraction and DTA analysis. Compressive strength and capillary absorption tests were realized on mortars constituted by 5, 10 and 15% red mud in replacement of cement. When calcined at 600 deg C, the red mud develops good pozzolanic properties, and the compressive strength of mortars produced with this waste meet values in accordance with regulatory standard. These results shown than red mud can be used, in partial replacement of cement, as new construction material to produce sustainable mortars with low environmental impact. (author)

  8. 全尾砂新型充填胶凝材料开发及其水化机理探讨%Discussion on exploitation of new backfilling cementing materials with unclassified tailings and associated hydration mechanisms

    Institute of Scientific and Technical Information of China (English)

    李茂辉; 杨志强; 高谦; 王有团

    2015-01-01

    Based on the characteristics of unclassified tailings in the Sijiaying iron mine, experimental research on exploitation of new backfilling cementing materials that can replace the cement was carried out using lime, desulfurization gypsum, slag, and other solid wastes. Using scanning electron microscopy ( SEM) and X⁃ray diffraction ( XRD) analysis, the hydration mechanisms of the new backfilling cementing materials were analyzed, and the optimum ratio of activators was determined. The results show that the strength of the new backfilling cementing materials can meet the filling body strength requirements for safe mining in the Sijiaying iron mine when the mass fractions of slurry, lime, and desulfurization gypsum are 68%, 3. 5%, and 16. 0%, respectively, and the cement⁃sand ratio is 1∶8. The results also show that the new backfilling cementing materials have a more compact structure and coarser occurrence when compared with the cement. The hydration products of the new backfilling cementing materials are mainly AFt crystals and C⁃S⁃H gel, which greatly increases the age strength of the new backfilling cementing materials.%针对司家营铁矿全尾砂,利用石灰、脱硫石膏、矿渣等固体废弃物开展替代水泥的新型充填胶凝材料试验研究,并通过电镜扫描( SEM)和X射线衍射( XRD)分析,研究新型充填胶凝材料激发剂的水化机理,确定激发剂优化配比。研究表明,当料浆质量分数为68%、胶砂比为1∶8、石灰质量分数为3.5%、脱硫石膏质量分数为16.0%时能够满足司家营铁矿南区嗣后充填法采矿对充填体强度的要求。结果显示,新型充填胶凝材料胶砂体与水泥胶砂体相比,结构更致密、产状更粗大,水化产物主要为AFt晶体和无定型C⁃S⁃H凝胶,从而大幅度提高了新型充填胶凝材料胶砂体的龄期强度。

  9. Cements in Radioactive Waste Disposal

    International Nuclear Information System (INIS)

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

  10. Microscopic evaluation regarding time behavior of orthodontic cements used for disjunctor cementing

    Directory of Open Access Journals (Sweden)

    Ruxandra Bartok

    2015-11-01

    Full Text Available In order to fulfill their function, orthodontic devices must be cemented on teeth using orthodontic rings. The retention of the orthodontic ring is influenced mainly by the type of dental-ring adhesion. This study was initiated to determine possible microleakage events while using zinc phosphate cement Adhesor (Spofa Dental, conventional glass ionomer Ketac Cem (3M ESPE and Fuji Ortho (GC and a compomer Transbond Plus (3M Unitek. The results of the study are consistent with those reported in the literature reference, the compomer is the preferred adhesive material for cementing the orthodontic rings, compared to conventional glass ionomer cements and zinc-phosphate cement.

  11. Spanish LLW and MLW disposal: durability of cemented materials in (Na, K)Cl simulated radioactive liquid waste.

    Science.gov (United States)

    Goñi, S; Guerrero, A; Hernández, M S

    2001-01-01

    The microstructural stability or durability of a specific backfilling pozzolanic-cement mortar, which is employed in Spain, in concrete containers for the storage of low level liquid wastes (LLW) and medium level liquid wastes (MLW), has been studied by means of the Koch-Steinegger test at the temperatures of 20 and 40 degrees C during a period of 365 days. Mortar samples were immersed in salt solutions of 3.46 M NaCl and 3.46 M KCl to simulate the salinity of some radioactive liquid waste matrices. The resistance of the mortar to the saline solution attack is evaluated by the development of the relative flexural strength. The changes of the microstructure were followed by mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Pore solution was extracted and analyzed at different periods of time to know the possible diffusion of sodium, chloride and potassium inside the microstructure. PMID:11150135

  12. Characterization of cement composites with mineral additives

    OpenAIRE

    Korat, Lidija

    2015-01-01

    Doctoral dissertation is aimed at characterizing cement composites with mineral additives representing the industrial waste material (fly ash, granulated blast furnace slag and biomass fly ash). Their usage can replace high cement shares in individual cases and is, however, favourable due to the production costs reduction and environment burden decrease, including the decreased emission of greenhouse gases as well as lower energy use. Cement composites (in fresh or hardened state)...

  13. Premixed calcium silicate cement for endodontic applications

    OpenAIRE

    Persson, Cecilia; Engqvist, Håkan

    2011-01-01

    Calcium silicate-based materials (also called MTA) are increasingly being used in endodontic applications. However, the handling properties of MTA are not optimal when it comes to injectability and cohesion. Premixing the cements using glycerol avoids these issues. However, there is a lack of data on the effect of common cement variables on important properties of premixed cements for endodontic applications. In this study, the effects of liquid-to-powder ratio, amount of radiopacifier and am...

  14. Water dynamics in glass ionomer cements

    Science.gov (United States)

    Berg, M. C.; Jacobsen, J.; Momsen, N. C. R.; Benetti, A. R.; Telling, M. T. F.; Seydel, T.; Bordallo, H. N.

    2016-07-01

    Glass ionomer cements (GIC) are an alternative for preventive dentistry. However, these dental cements are complex systems where important motions related to the different states of the hydrogen atoms evolve in a confined porous structure. In this paper, we studied the water dynamics of two different liquids used to prepare either conventional or resin-modified glass ionomer cement. By combining thermal analysis with neutron scattering data we were able to relate the water structure in the liquids to the materials properties.

  15. Chemical alteration of cement materials in a radioactive waste repository environment. 1. Thermodynamic modelling for the dissolution and precipitation of calcium silicate hydrates

    International Nuclear Information System (INIS)

    Cementitious material, a potential waste packaging and backfilling material for the disposal of radioactive waste, is expected to provide both physical and chemical containment. In particular the ability to provide high-pH conditions, which depends on the solubility of the constituent hydrated minerals in cement matrices, is a very important parameter when considering the release of radionuclides from radio active wastes. For long-term safety assessment, it is necessary to develop a series of predictive calculation models. Several models have been proposed for the incongruent dissolution of calcium silicate hydrate (C-S-H) gel, which is the principal product of hydrated cement phases. In the repository, the re-precipitation of minerals would follow their dissolution when an equilibrated solution moves to the other regions and equilibrates with the constituent minerals there. However, previous models have not yet adequately quantitatively evaluated the re-precipitation or interaction of other minerals with the dissolution of C-S-H gel. In this study, therefore, a thermodynamic dissolution and precipitation model of C-S-H gel is proposed assuming a binary non-ideal solid solution of Ca(OH)2 and Si02. Dissolution and precipitation experiments on C-S-H gel were performed. C-S-H precipitates were prepared using two techniques. One was based on hydrolysis in a mixture of Ca and Si solutions and produced homogeneous gels. With the other technique, precipitates were prepared by contacting Ca(OH)2 solution with C-S-H gel with low Ca/Si ratios (0.47, 0.65, 0.9). The results were well predicted by the proposed model. Dissolution experiments on C-S-H gel coexisting with ettringite were also carried out. At Ca/Si>l.2 in C-S-H gel, the equilibrated pH and Ca and Si concentrations are nearly the same as those for C-S-H gel alone. At lower Ca/Si, interaction between ettringite and C-S-H dissolution was observed more clearly. The measured pH and Ca and Si concentrations were

  16. Modelisation et resolution de problemes d'optimisation combinatoire issus d'applications spatiales

    OpenAIRE

    Mancel, Catherine

    2004-01-01

    Nos travaux portent sur la modelisation et la resolution de problemes d'optimisation combinatoire emergeant dans le cadre de la planification de missions spatiales. Ces problemes de grande taille presentent des caracteristiques communes en termes de types de donnees, de contraintes et de criteres a optimiser. Nous nous focalisons sur l'apport de la programmation lineaire pour ces problemes, associee a des methodes de simplification de l'espace de recherche, par decomposition ou grace a des te...

  17. Shear bond strength of glass-ionomer cements to dentin: Effects of dentin depth and type of material activation Resistência ao cisalhamento da união de cimentos de ionômero de vidro à dentina: Efeitos da profundidade do substrato e do tipo de ativação do material

    OpenAIRE

    Elda PISANESCHI; Rubens Corte Real de CARVALHO; Edmir MATSON

    1997-01-01

    The purpose of this study was to determine, through the shear bond strength of in vitro tests, that the type of glass-ionomer cements (conventional or hybrid) and dentin depth (superficial or deep) are factors that may influence the adhesion of these materials to the dentin structure. Specimens of two conventional glass-ionomer cements (Vidrion R® - SS White and Chelon Fil®- Espe) and a hybrid-glass ionomer cement (Vitremer® - 3M) were separated in groups and prepared for the shea...

  18. 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.

  19. 水泥混凝土路面填缝料疲劳试验方法研究%Research on Fatigue Test Methods for Joint Sealing Materials for Cement Concrete Pavement

    Institute of Scientific and Technical Information of China (English)

    王宝松; 王进勇; 龙丽琴

    2012-01-01

    水泥混凝土路面填缝料在实际应用中,受气候、机械外力作用产生疲劳老化,使用寿命下降.填缝料疲劳导致地表水渗入基层是水泥混凝土路面破坏的重要原因之一.现有填缝料评价体系中无体现疲劳性能的评价指标.基于对现有水泥混凝土路面接缝料的力学研究和室内试验,提出适合于水泥混凝土路面填缝料疲劳性能检测的试验方法和仪器,其对于水泥混凝土路面填缝料的研究及应用具有重要意义.%Joint sealing materials for cement concrete pavement in practical application produce fatigue aging under effect of climate and mechanical force and the service life decreases. Penetration of surface water into base course caused by fatigue of joint sealing materials is one of important reasons for damage to cement concrete pavement. Existing evaluation system for joint sealing materials has no evaluation indices for fatigue performance. On the basis of mechanical research and indoor test for joint sealing materials for cement concrete pavement, this paper proposes test methods and instruments suitable for detection of fatigue performance of joint sealing materials for cement concrete pavement, which show importance significance for research and application of joint sealing materials for cement concrete pavement.

  20. 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.

  1. US cement industry

    Energy Technology Data Exchange (ETDEWEB)

    Nisbet, M.A.

    1997-12-31

    This paper describes the cement and concrete industry, and provides data on energy use and carbon dioxide emissions. The potential impact of an energy tax on the industry is briefly assessed. Opportunities identified for reducing carbon dioxide emissions include improved energy efficiency, alternative fuels, and alternative materials. The key factor in determining CO{sub 2} emissions is the level of domestic production. The projected improvement in energy efficiency and the relatively slow growth in domestic shipments indicate that CO{sub 2} emissions in 2000 should be about 5% above the 1990 target. However, due to the cyclical nature of cement demand, emissions will probably be above target levels during peak demand and below target levels during demand troughs. 7 figs., 2 tabs.

  2. Study on the Relation between Material Composition and Performance of the Porous Composites of Cement Treated Crushed Stone%水泥稳定碎石多孔性材料的组成与性能探讨

    Institute of Scientific and Technical Information of China (English)

    李立寒; 郭忠印

    2001-01-01

    Aggregate gradation and cement content are important factors that affect the porousness,the permeability coefficient, the strength and modulus of cement treated crushed stone. Samples of five open-graded aggregates, and four levels of cement content were tested in"drainage-lag"permeameter developed by Barber and Sawyer, and then the samples were tested in compressive strength and modulus of resilience. The relations between material composition and performance of cement treated crushed stone were discussed and the regression equations were developed on the basis of laboratory tests and stepwise regression analysis. These results provide valuable guide for the mix design of cement treated crushed stone.%根据室内试验结果,对水泥稳定碎石多孔性材料的组成与其孔隙率、渗透系数、强度和模量的关系进行了分析,探讨了集料级配、水泥用量等因素的影响.通过逐步回归分析,建立了水泥稳定碎石材料组成与性能之间的回归公式.在此基础上,探讨了水泥稳定碎石的组成设计方法。

  3. Effect ofAuxiliary Cementing Materials on the SulphateAluminium Cement%辅助凝胶材料对硫铝酸盐水泥性能影响研究

    Institute of Scientific and Technical Information of China (English)

    刘文斌

    2013-01-01

      研究普通硅酸盐水泥、石膏及石灰掺入硫铝酸盐水泥中后对其凝结时间和强度的影响。研究表明:普通硅酸盐水泥掺量增大使得硫铝酸盐水泥凝结时间缩短,强度下降;石灰和石膏的掺入对硫铝酸盐水泥水化有一定的促进作用,且适当的比例对硫铝酸盐水泥的后期强度无不利影响。普通硅酸盐水泥、石灰和石膏的混掺对硫铝酸盐水泥的影响大小则与其掺量的多少有关。%The setting time and strength of sulphate aluminium cement admixed with Portland cement, gypsum and lime were studied. The result indicated that the setting time shortened and the strength declined with Portland cement content increasing. Lime and gypsum could promote hydration of sulphate aluminium cement, and they would be not unfavorable to late strength of sulphate aluminium if there was an appropriate proportion. The performance of sulphate aluminium cement was relevant to their mixing content.

  4. A Blended Cement Containing Blast Furnace Slag and Phosphorous Slag

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Blended cement containing blast furnace slag(BFS) and phosphorous slag(PS) is a new kind of cement.The total content of blended materials could increase if two additives were used. Using the same admixtures, the properties of the blended cement with 70% additives could reach the standard of 525-grade slag cement according to GB.The strength of cement with 80% additives could reach the standard of 425-grade slag cement.The tests of strength, pore structure,hydration products,inhibiting alkali-aggregate reaction, resistance to sulfate corrosion of BFS-PSC were performed.

  5. Case Study of the California Cement Industry

    OpenAIRE

    Coito, Fred; Powell, Frank; Worrell, Ernst; Price, Lynn; Friedmann, Rafael

    2005-01-01

    California is the largest cement producing state in the U.S., accounting for between 10 percent and 15 percent of U.S. cement production and cement industry employment. The cement industry in California consists of 31 sites that consume large amounts of energy, annually: 1,600 GWh of electricity, 22 million therms of natural gas, 2.3 million tons of coal, 0.25 tons of coke, and smaller amounts of waste materials, including tires. The case study summarized in this paper focused on providi...

  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...

  7. Scanning electron microscopy analysis of dental cements

    Directory of Open Access Journals (Sweden)

    Radosavljević Radivoje D.

    2009-01-01

    Full Text Available The aim of this study was to compare in vitro the characteristics of different types of luting cements (zinc phosphate, glass-ionomer and resin based composite cement using scanning electron microscopy (SEM analysis and microleakage for the quality range of materials. Dental cements were mixed in accordance with the manufacturer's instructions and formed with posts in dental root canals of extracted teeth. The quality of cement was determined by SEM observation on horizontal sectioned roots with fixed posts according to specific pore and marginal gap diameter. The microleakage was measured on specimens immersed in Lofler (methylene blue solution. The mean values of the maximal diameter of pores, marginal gaps and microleakage of conventional cements are remarkably larger in comparison with composite luting agents. In conclusion, the quality and efficiency of composite luting agents in comparison with conventional cements are more successful in protecting the interior of tooth from penetration of oral fluids, bacteria and bacterial toxins into unprotected dentine.

  8. 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

    necessity to modernize technological equipment used for grinding raw material components with the purpose to improve efficiency and quality, power- and resource saving. The possibility of using various grinding aids that permit to increase grinding productivity is shown in the paper. The paper studies an automation concept of the control system which used for grinding process of mineral raw material. A conceptual model for complexation of various methods grinding aids has been proposed in the paper. The paper presents methodological principles for simulation of technological process used for processing of mineral raw material while producing cement and silicate products. The parameters which are to be controlled and which are necessary for development of computer simulations of technological grinding process have been determined in the paper. The paper justifies an application of imitation simulation for creation of computer models. Methodology for imitation simulation of the technological process has been studied in the paper. The paper confirms the possibility to use analytical and probability methods. Imitation simulations of a grinding mill operation have been developed on the basis of experimental data and probability functions. The possibility of controlling technological process of raw material grinding has been demonstrated in the paper.While implementing the proposed complex of organizational and technical recommendations it is possible to increase grinding productivity up to 30-50 % and significantly reduce и существенно снизить energy consumption for mineral raw material grinding during production of cement and silicate products. The combined reengineering methodology for grinding process including all the mentioned intensification methods substantially increases quality of final products and reduces its self-cost that will favour its compatibility and attractiveness for consumers.

  9. Flow and heat transfer thermohydraulic modelisation during the reflooding phase of a P.W.R.'s core

    International Nuclear Information System (INIS)

    Some generalities about L.O.C.A. are first recalled. The French experimental studies about Emergency Core Cooling System are briefly described. The different heat transfer mechanisms to take into account, according to the flow pattern in the dry zone, and the correlations or methods to calculate them, are defined. Then the Thermohydraulic code computer: FLIRA, which describe the reflooding phase, and a modelisation taking into account the different flow patterns are setted. A first interpretation of ERSEC experiments with a tubular test section shows that it is possible, with this modelisation and some classical heat transfer correlations, to describe the reflooding phase.

  10. 基于压汞法的水泥固化淤泥持水特性研究%Study on Water Retention Property of Cemented Dredged Material Based on MIP

    Institute of Scientific and Technical Information of China (English)

    胡孝彭; 赵仲辉

    2016-01-01

    The study on water retention property of cemented dredged material ( DM) is presented. Soil water characteristic curves ( SWCCs) of cemented DM with different initial water contents and cement contents were measured by filter paper methods and pore size distributions were measured by mercury intrusion porosimetry ( MIP ) . Water holding capacity of the cemented DM was discussed and the measured pore size distributions were used to predict the SWCCs of cemented DM. The test results show that water holding capacity of the cemented DM increases with increasing of the cement content for given initial water content and it decreases with increasing initial water content for a given cement content. Pore size distribution of cemented DM is unimodal. The predicted SWCCs are consistent with the measured curves if no remarkable drying shrinkage occurs. On the other side, the predicted SWCCs are higher than the measured curves for specimens subjected to remarkable drying shrinkage.%为深入探究固化淤泥的持水特性,通过试验量测不同初始含水率和水泥添加量下固化淤泥的土水特征曲线,基于压汞试验获得其孔径分布曲线,分析固化淤泥的持水特性并据其孔径分布预测了土水特征曲线。结果表明:同一初始含水率条件下固化淤泥的持水能力随水泥添加量的增加而增强,相同水泥添加量下其持水能力随初始含水率的增加而减弱;固化淤泥的孔径分布曲线呈单峰,若其在干燥过程中不发生收缩或收缩较小,则据孔径分布预测的土水特征曲线与实测曲线吻合较好,否则,预测的土水特征曲线高于实测曲线。

  11. The effects of ambient temperature and mixing time of glass ionomer cement material on the survival rate of proximal ART restorations in primary molars

    Directory of Open Access Journals (Sweden)

    Arthur M Kemoli

    2014-01-01

    Full Text Available Objective: Temperature fluctuations and material mixing times are likely to affect the consistency and integrity of the material mixture, and hence the restoration made out of it. The purpose of the present study was to determine the influence of the ambient temperature and the mixing time of glass ionomer cement (GIC restorative material on the survival rate of proximal atraumatic restorative treatment (ART restorations placed in primary molars. Materials and Methods: A total of 804 restorations were placed in the primary molars of 6-8-year-olds using the ART approach. The restorations were then followed for a period of 2 years and evaluated at given intervals. The data collected were analyzed using SPSS computer statistical program, and the results tested and compared using the Chi-square, Kaplan Meier survival analysis and Cox Proportional hazard statistical tests. Results: The cumulative survival rate of the restorations dropped from the initial 94.4% to 30.8% at the end of 2 years. The higher survival rate of the restorations was associated with the experienced operators and assistants when using the rubber dam isolation method. However, there was no statistically significant difference in the survival rate of the restorations when related to the room temperature and the mixing time of the GIC materials used in spite of the variations in the temperature recoded and the methods used in mixing the materials. Conclusion: The ambient temperature and mixing time of GIC did not have a significant effect on the survival of the proximal ART restorations.

  12. 胶凝材料性质对干混砂浆抗压强度的影响研究%Influence of the properties of cementing materials on the unconfined compressive strengths of dry-mixed mortar

    Institute of Scientific and Technical Information of China (English)

    郑娟荣; 赵雪飞

    2014-01-01

    为了研究胶凝材料性质对干混砂浆抗压强度的影响规律,共制备了24组样品,其中3组样品的微观形貌和孔结构采用扫描电子显微镜和压汞测孔仪(Autopore IV 9500)等测试手段进行了分析。试验结果表明:无论胶凝材料是100%水泥、50%水泥+50%矿渣粉和50%水泥+50%粉煤灰,7 d和28 d砂浆抗压强度均随胶凝材料总量增加而明显提高,增加水泥掺量对砂浆早期强度有利;与以100%水泥为胶凝材料制备的砂浆相比,当每吨干混砂浆中胶凝材料总量分别为100、150、200、250 kg时,以50%水泥+50%矿渣粉为胶凝材料制备的砂浆的抗压强度分别提高47%、55%、10%和0,而以50%水泥+50%粉煤灰为胶凝材料制备的砂浆的抗压强度分别降低77%、66%、56%和44%。与15%水泥制备的砂浆28 d硬化体相比,7.5%水泥+7.5%矿渣制备的砂浆28 d硬化体中水化产物更多或更分散、基体与骨料结合更密实、总孔隙更低及孔径更细;7.5%水泥+7.5%粉煤灰制备的砂浆28 d硬化体中水化产物更少、基体更松散、总孔隙更高及孔径更大。%24 groups of samples were made so as to investigating the influence of the properties of cementing materials on the uncon-fined compressive strengths (UCS) of dry-mixed mortar.The morphology and pore structure of 3 groups of 24 samples were investigated by scanning electron microscope(SEM) and mercury intrusion porosimeter(Autopore IV 9500)(MIP).The results showed that the 7 d and 28 d UCS of hardened mortars increased with the increase of the total content of cementing materials no matter what cementing materials were 100%cement and 50%cement+50%slag powder and 50%cement+50%fly-ash ,and the increase of cement content was in favour of early strength of hardened mortar.Comparing with the hardened mortar of 100%cement as cementing material ,the 28 d UCS of the hard-ened mortar of 50%cement+50%slag powder as cementing material respectively

  13. 粉煤灰对矿渣胶结充填材料性能的影响%Influence of Fly Ash Performance of Slag Cemented Backfilling Materials

    Institute of Scientific and Technical Information of China (English)

    董璐; 高谦; 南世卿; 何环莎

    2012-01-01

    In view of the features of fly ash as abundant resources,low costs and improving the construction of mortar, the influence of fly ash on strength and liquidity of slag cemented materials is studied through experiments. The results show that the slag cemented backfilling materials with the lime and desulfurization gypsum as the activator, the compressive strength of backfilling body gradually declined with the adding amount of fly ash increasing. 1% of fly ash is added each time,the intensity decreased by 1. 82% at 7 d and by 1. 61% at 28 d on average. Meanwhile,the yield stress and viscosity of the backfilling is getting lower,which indicates that fly ash can largely improve the rheology of backfilling materials,and make high concentration of mortars conveying by gravity flow. Comprehensively considering the strength and the rheology, the optimal dosage of the fly ash ranges from 10% to 20%.%针对粉煤灰具有来源广、价格低廉和能改善砂浆施工性能的特点,研究了粉煤灰对矿渣胶结充填材料强度和流动性的影响.结果表明:在以石灰和脱硫石膏为激发剂制备的矿渣胶凝材料中,随着粉煤灰添加量的不断增大,充填体的抗压强度逐渐下降,每添加1%的粉煤灰,7d强度平均降低1.82%,28 d强度平均降低1.61%;但是充填料的屈服应力和塑形黏度却在不断降低,说明粉煤灰的添加能够很好地改善充填料浆的流变性,实现砂浆高浓度自流输送.综合考虑强度和流变性的影响效果,粉煤灰的最优掺量范围为10%~ 20%.

  14. A new geopolymeric binder from hydrated-carbonated cement

    OpenAIRE

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

    2012-01-01

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

  15. Practical clinical considerations of luting cements: A review

    OpenAIRE

    Lad, Pritam P; Kamath, Maya; Tarale, Kavita; Kusugal, Preethi B

    2014-01-01

    The longevity of fixed partial denture depends on the type of luting cement used with tooth preparation. The clinician’s understating of various cements, their advantages and disadvantages is of utmost importance. In recent years, many luting agents cements have been introduced claiming clinically better performance than existing materials due to improved characteristics. Both conventional and contemporary dental luting cements are discussed here. The various agents discussed are: Zinc pho...

  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. 膏体充填专用胶结料的研究与应用%Research and Application of Cream-body Filling Special Cement Material

    Institute of Scientific and Technical Information of China (English)

    张旺; 李新磊

    2015-01-01

    膏体充填开采技术是绿色开采技术的重要组成部分,是解决煤矿开采环境问题的理想途径。但随着煤炭价格降低,充填材料在成本中的占比不断上涨,传统的膏体充填工艺成本太高,通过使用专用充填胶结料,优化充填配比,对充填成本起到较好的控制作用。%The cream-body iflling is an important part of the green mining,is the ideal way to solve environmental problems.But with a sudden turn for the worse in coal prices,the rising price of cream-body iflling materials, the cost is too high, through the use of special cementing material, optimization of cream-body ratio,have good control effect for the cost of cream-body iflling.

  18. A Numerical Comparison of Ionic Multi-Species Diffusion with and without Sorption Hysteresis for Cement-Based Materials

    DEFF Research Database (Denmark)

    Jensen, Mads Mønster; Johannesson, Björn; Geiker, Mette Rica

    2015-01-01

    A finite element solution for a mass transport model for porous materials accounting for sorption hysteresis is presented in this paper. The model is prepared for modeling of concrete durability, but the general presentation makes it suitable for other porous materials like soil and tissues...

  19. Effect of Abutment Modification and Cement Type on Retention of Cement-Retained Implant Supported Crowns

    OpenAIRE

    Mitra Farzin; Kianoosh Torabi; Ahmad Hasan Ahangari; Reza Derafshi

    2014-01-01

    Objective: Provisional cements are commonly used to facilitate retrievability of cement-retained fixed implant restorations; but compromised abutment preparation may affect the retention of implant-retained crowns.The purpose of this study was to investigate the effect of abutment design and type of luting agent on the retentive strength of cement-retained implant restorations. Materials and Method: Two prefabricated abutments were attached to their corresponding analogs and embedded in an ac...

  20. 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

  1. 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.

  2. Research of dynamic mechanical performance of cement rock

    Institute of Scientific and Technical Information of China (English)

    WANG Qiang; WANG Tong; WANG Xiang-lin

    2007-01-01

    As Daqing Oilfield is developing oil layer with a big potential, the requirement for the quality of well cementation is higher than ever before. Cement rock is a brittle material containing a great number of microcracks and defects. In order to reduce the damage to cement ring and improve sealed cementing property at the interface, it is necessary to conduct research on the modification of the cement rock available. According to the principle of super mixed composite materials, various fillers are added to the ingredients of cement rock. Dynamic fracture toughness of cement rock will be changed under the influence of filler. In order to study the damage mechanism of the cement circle during perforation and carry out comprehensive experiments on preventing and resisting connection, a kind of comprehensive experiment equipment used to simulate perforation and multifunctional equipment for testing the dynamic properties of the material are designed. Experimental study of the dynamical mechanical performance of original and some improved cement rock and experiment used to simulate the well cementation and perforation are carried out. Standard for dynamical mechanical performance of the cement rock with fine impact resistance and mechanical properties of some improved cement rock are also given.

  3. Antibacterial activity of selected glass ionomer cements

    Directory of Open Access Journals (Sweden)

    Elżbieta Łuczaj-Cepowicz

    2014-01-01

    Full Text Available Introduction: The aim of the paper was to determine the antibacterial activity of four glass ionomer cements against bacteria of the genera Streptococcus and Lactobacillus. Material and methods: Four capsulated glass ionomer cements were applied in the study: Fuji Triage (GC, Fuji IX (GC, Ketac Molar (3M Espe and Ketac Silver (3M Espe. Four standard bacterial strains were used to assess the antibacterial activity of the studied cements: Streptococcus mutans, S. sanguis, S. salivarius and Lactobacillus casei. The antibacterial activity was determined by the agar diffusion method. The bacterial suspension was spread with a cotton swab on TSA plates. For each material six wells (7 mm diameter, 5 mm deep were made with a cork borer. Each well was then filled with freshly prepared cements. The results were obtained by measuring the bacterial growth inhibition zone after 1, 2, 3 and 7 days. Results: Fuji Triage cement inhibited the growth of all bacterial strains. Fuji IX cement demonstrated the most potent antibacterial activity against S. sanguis. Ketac Molar showed antibacterial activity against S. sanguis and S. salivarius, whereas Ketac Silver was efficient against S. mutans as well. Neither of the Ketac cements inhibited growth of the standard L. casei strain. Discussion: Antibacterial activity of glass ionomer cements has attracted the interest of scientists in recent years. Most authors, including us, carried out experiments using the agar diffusion method and demonstrated antibacterial activity of glass ionomer cements. Different antibacterial activity of glass ionomer cements, observed in our study and studies of other authors, depended on the evaluated cement, bacterial strain and period of evaluation.

  4. Evaluation of long-term interaction between cement and bentonite for geological disposal (2) XAFS analysis of calcium silicate hydrate precipitates at cementitious and bentonite material interface

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Numerical analyses of the long-term alteration of the engineered barriers used for the disposal of TRU waste predicted precipitation of C-S-H minerals at the interface between the cementitious materials and the bentonite-based buffer. When the C-S-H precipitates at this interface, the diffusion coefficient in the engineered barriers will decrease, resulting in reduced mass transport, which feeds back to reduce the rate of subsequent alteration. The C-S-H predicted to form at the cement-bentonite interface could not be identified directly using conventional analytical tools, including XRD, due to its low crystallinity. The authors propose that XAFS analysis, which provides spectra sensitive to the valency and coordination of the element of interest regardless of its crystallinity, would be capable of characterizing the C-S-H. The presence of the C-S-H precipitated as a secondary mineral has already been confirmed by applying chemical and XAFS analyses to bentonite specimens collected from the compacted bentonite-cement interface. However, because of the limitations on the width of specimens that can be collected by cutting from block samples, i.e. approximately 1 mm, detailed concentration profiles could not be obtained for this secondary C-S-H. In this study, XAFS spectra of thin specimens were measured using an X-ray detector in order to obtain detailed concentration profiles for the C-S-H formed at the interface between the cementitious material and the bentonite-based buffer. The X-ray detector used in the XAFS analysis consists of 1024 photodiodes arranged in line with a 0.025 mm pitch (photodiode array; PDA). Ca-K-edge XAFS measurements were conducted at the Photon Factory of the KEK. The synchrotron was operated in top-up mode with 450 mA during the measurements. Specimens were taken from a contact sample of compacted bentonite (Kunigel V1; dry density of 1.6 g/cm3) and hardened OPC (w/c = 0.6) immersed in

  5. The hydrothermal stability of cement sealing materials in the potential Yucca Mountain high level nuclear waste repository

    International Nuclear Information System (INIS)

    Cementitious materials, together with other materials, are being considered to seal a potential repository at Yucca Mountain. A concern with cementitious materials is the chemical and mineralogic changes that may occur as these materials age while in contact with local ground waters. A combined theoretical and experimental approach was taken to determine the ability to theoretically predict mineralogic changes. The cementitious material selected for study has a relatively low Ca:Si ratio approaching that of the mineral tobermorite. Samples were treated hydrothermally at 200 degrees C with water similar to that obtained from the J-13 well on the Nevada Test Site. Post-test solutions were analyzed for pH as well as dissolved K, Na, Ca, Al, and Si. Solid phases formed during these experiments were characterized by scanning electron microscopy and X- ray diffraction. These findings were compared with predictions made by the geochemical modeling code EQ3NR/E06. It was generally found that there was good agreement between predicted and experimental results

  6. Migration of ions in cement paste as studied by SIMS

    Energy Technology Data Exchange (ETDEWEB)

    Prince, K.E.; Aldridge, L.P. [Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW (Australia); Rougeron, P. [Electricite de France Direction des Etudes et Recherches, Les Renardiers (France)

    1998-06-01

    Cement is often used to condition and encapsulate low level radioactive waste before it is disposed of in a repository. Ground water can attack these waste-forms by transporting aggressive ions into the cement paste and by removing radioactive ions from the paste. The extent of the attack will be governed by the diffusion of the ions in the cement paste. In this study we examine the migration of aggressive carbonate ions and inactive Cs and Sr through cement pastes. The use of SIMS for establishing the penetration depths and diffusion profiles for Cs and Sr in cement will be explored. The penetration profiles of Cs and Sr in a non-zeolite cement paste were examined and compared to those of a paste made with zeolite. The effects of the non-homogeneous nature of the cement was most pronounced in the study of the zeolite rich cement; Cs being preferentially accumulated in the zeolite material. (authors). 4 refs., 2 figs.

  7. 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) was cond......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...

  8. Self-cleaning and depollution of fiber reinforced cement materials modified by neutral TiO2/SiO2 hydrosol photoactive coatings

    Science.gov (United States)

    Wang, Jian; Lu, ChunHua; Xiong, JiRu

    2014-04-01

    Environmental pollution has an evidently adverse impact on the buildings that are constructed by the glass fiber reinforced cement (GRC) materials. In the present work, the stable, neutral TiO2/SiO2 hydrosols were prepared by using the Ti(SO4)2 as titanium source, HNO3 as peptizing agent, and SiO2 as stabilizer through a simple and low cost process. The morphologies and structures of TiO2/SiO2 hydrosol were further characterized by the TEM, SEM, XRD, and FTIR measurement. In the synthetic hydrosol, lots of nanoparticles with the diameters in the range of 10-20 nm can be observed. Tisbnd Osbnd Si band were formed, as observed from the FTIR spectrum. The Na2O·SiO2 was detected from the SEM. After drying the TiO2/SiO2 hydrosol, the XRD shown that the TiO2 has an anatase structure and the SiO2 is amorphous. The TiO2/SiO2 hydrosol can be compactly coated on the GRC surface due to the existence of Na2O·SiO2 binder and exhibited high photocatalytic activity and stability in the degradation of Rhodamine B.

  9. Compound effect of CaCO{sub 3} and CaSO{sub 4}·2H{sub 2}O on the strength of steel slag: cement binding materials

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Liqian; Liu, Jiaxiang; Liu, Qian, E-mail: ljxpost@263.net [Beijing Key Laboratory of Electrochemical Process and Technology for Materials, The State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing (China)

    2016-03-15

    In this study, we replaced 30% of the cement with steel slag to prepare binding material; additionally, small amounts of CaCO{sub 3} and CaSO{sub 4}·2H{sub 2}O were added. This was done to study the compound effect of CaCO{sub 3} and CaSO{sub 4}·2H{sub 2}O on the strength of steel slag-cement binding materials. The hydration degree of the steel slag cementitious material was analyzed by XRD, TG and SEM. The results showed that the optimum proportions of CaCO{sub 3} and CaSO{sub 4}·2H{sub 2}O were 3% and 2%, respectively. Compared with the steel slag-cement binders without adding CaCO{sub 3} and CaSO{sub 4}·2H{sub 2}O, the compressive strength increased by 59.9% at 3 days and by 17.8% at 28 days. Acting as the nucleation matrix, CaCO{sub 3} could accelerate the hydration of C{sub 3}S. In addition, CaCO{sub 3} was involved in the hydration reaction, generating a new hydration product, which could stably exist in a slurry. Meanwhile, CaSO{sub 4}·2H{sub 2}O could increase the number of AFt. The compound effect of CaCO{sub 3} and CaSO{sub 4}·2H{sub 2}O enhanced the intensity of steel slag-cement binding materials and improved the whole hydration behavior. (author)

  10. Processing and characterisation of Calcium SulfoAluminate (CSA) eco-cements coated with a hybrid organo-inorganic material for photocatalytic applications

    OpenAIRE

    Morales-Cantero, Alejandro; Cabeza, Aurelio; De la Torre, Ángeles G.; Aranda, M. A. G.; Santacruz, Isabel

    2015-01-01

    On the one hand, Calcium SulfoAluminate (CSA) eco-cements are receiving increasing attention since their manufacture produces up to 40% less CO2 than ordinary Portland cement (OPC). In addition, they show interesting properties such as high early-age strengths, short setting times, impermeability, sulfate and chloride corrosion resistance and low alkalinity. On the other hand, water treatment is a key issue and it will become much more important in the decades ahead. We have developed a p...

  11. 中国超细晶硬质合金及原料制备技术进展%Development on Preparation Technology of Ultrafine-Grained Cemented Carbides and Their Raw Materials in China

    Institute of Scientific and Technical Information of China (English)

    吴冲浒; 聂洪波; 肖满斗

    2012-01-01

    The sintered WC-Co with uhrafine grain sizes ( 〈 0. 5 rim) is called ultrafine cemented carbide, which pos- sesses optimized properties such as hardness and strength. Efficient tools prepared by uhrafine cemented carbides have been used in aerospace, nuclear energy, automotive, generating equipment, new energy and other fields of electronic communications. The development of uhrafine cemented carbides and raw materials was systematically introduced and reviewed, mainly in aspects of the preparation, property and characterization of uhrafine tungsten carbide powder, ultrafine cobalt powder, WC-Co composite powder and ultrafine cemented carbides in China. Prospects on technology of the ultra-fine cemented carbide were discussed finally.%超细晶硬质合金是WC晶粒度≤0.5μm的硬质合金,这类合金具有高强度和高硬度的优异性能。目前由超细晶硬质合金制备的高效刀具已经广泛用于航空航天、核能、汽车、发电设备、新能源和电子通讯等现代制造业。主要对中国超细晶硬质合金原料(例如超细碳化钨粉、钴粉、复合粉)和超细晶硬质合金制备技术、性能及表征方法作了系统的阐述。最后对超细晶硬质合金制备技术进行了展望。

  12. 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。

  13. Development of Clinical Cement of Nanoapatite and Polyamide Composite

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new type of inorganicorganic biomimetic bone cement consisting of nanohydroxyapatite and polyamide 66 composite was investigated. This cement can be handled as paste and easily shaped into any contour. Nanoapatite and polyamide composite cement has a reasonable setting time, excellent washout resistance, high mechanical strength and bioactivity, and it is easily handled and shaped, which can be developed as a clinical cement. It can be predicted that nanoapatite/polymer composite cement would be a new trend of biomedical material, showing a promising prospect.

  14. 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.

  15. Neutron Scattering Studies of Cement

    Science.gov (United States)

    Allen, Andrew

    2010-03-01

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

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

    Directory of Open Access Journals (Sweden)

    Marilia P. de Oliveira

    2006-06-01

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

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

    OpenAIRE

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

    2011-01-01

    The present paper addresses the alkali activation of Portland cements containing blast furnace slag (20 and 30% of the cement by weight) with a view to the possible use of these materials in oil well construction. The hydration studies conducted showed that in cement/slag blends, the sodium silicate activating solution partially inhibited the dissolution of the silicate phases in the Portland cement, retarding cement hydration and reducing the precipitation of reaction products. D...

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

    OpenAIRE

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

    2015-01-01

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

  19. 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.

  20. Stabilization effects of surplus soft clay with cement and GBF slag

    Institute of Scientific and Technical Information of China (English)

    LU Jiang; Chirdchanin MODMOLTIN; Katsutada ONITSUKA

    2004-01-01

    Utilization of industrial waste and surplus construction soft clay as construction material was recommended, and many attempts at geotechnical waste utilization were undertaken. This study aimed at the application of cement and a kind of industrial wastes, i.e. granulated blast furnace slag, on stabilization of surplus soft clay. The results showed that the cement and slag can successfully stabilize Ariake clays even though this high organic clay fails to be stabilized by lime and cement. Addition of slag in cement for stabilization induces higher strength than cement alone for longer curing time. The application of the cement with slag is more suitable than cement alone for stabilization because of economical consideration.

  1. 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.

  2. High levels of dioxin-like PCBs found in organic-farmed eggs caused by coating materials of asbestos-cement fiber plates: A case study.

    Science.gov (United States)

    Winkler, Jörg

    2015-07-01

    During a regional monitoring project of organic-farmed, free-range and cage-free eggs, high levels of dioxin-like compounds were detected in organic-farmed eggs, using the dioxin responsive chemical-activated luciferase gene expression (DR-CALUX®) bioassay. Further evaluations performed with GC-HRMS (gas chromatography in combination with high resolution mass spectrometry) revealed elevated amounts of non-dioxin-like (non-dl) polychlorinated biphenyls (PCBs) dominated by most lipophilic congeners like PCB 138, 153 and 180 and of dioxin-like (dl) PCBs, with a congener pattern in the descending order of PCB 118, 156, 167, 105, 189, 157, 105, 126 and PCB 77. Contaminations with polychlorinated dibenzo-p-dioxins (PCDDs) appeared of minor priority, with only hepta- and octa-substituted dioxins above their limits of quantification (LOQs). The pattern of polychlorinated dibenzofurans (PCDFs) was dominated by low amounts of tetra- and penta-chlorinated congeners. To identify the source of contamination, several samples of organic-farmed eggs, soil, laying hens, feedstuff, corrugated asbestos-cement cover plates (ACPs), stable dust and debris collected in the gutter of the stable, were analyzed. Comparing PCB congener-pattern of individual samples, the source was traced back to the coating of ACPs, which covered roof and sidewalls of the stable. Because coating materials probably have been used for roofing and cladding in many countries worldwide, there is a high probability that the presented case report is not a local incident but rather describes a new source of PCB contamination, yet widely unknown or underestimated. PMID:25898153

  3. Modeling of the ionic transfers in saturated porous media: application to the penetration of chlorides through cementing materials

    International Nuclear Information System (INIS)

    In this work, the problem of ionic species transport through concrete porous media has been documented. Chloride ions penetration in cementitious materials is one of the processes widely responsible for the degradation of concrete structures. Therefore there exists an immense need for its correct understanding and quantification. Different research groups worldwide have proposed different chloride ingress models. Here, a one-dimensional model based on a multi-species approach of the ionic transport is presented. It is the new version of a previous model MsDiff developed a few years ago in our group that describes the diffusion of ionic species with the Nernst-Planck equation instead of Fick's laws. This newer version is named, the package version of MsDiff after it requires a package of five input data at any given age of concrete. With a multi-species approach, it is possible to take into account the interactions, which exist among different ionic species in pore solution of concrete. The numerical scheme of the model is based on finite difference method with Crank-Nickolson and Law-Wendroff techniques. In order to run MsDiff, we do need an input data. Several experiments were performed accordingly to provide experimental feedback to MsDiff. Standard immersion tests were conducted to validate the outcomes of MsDiff. Special attention is given to the diffusion coefficients of the ions and the interactions between the ionic species and the solid phase. In addition to MsDiff, some other existing models were also tried for the sake of comparison with the experimental chloride profiles. Certain experimentation was conducted to watch the effect of exposure period, concrete age at exposure and concentration in the environmental solution. In the end, the simulations were performed with MsDiff in order to calculate the chloride-induced corrosion initiation time using the experimental data already achieved while making use of different criteria adopted by different research

  4. INFLUENCE OF GLASS CULLET IN CEMENT PASTES

    Institute of Scientific and Technical Information of China (English)

    A.Karamberi; E.Chaniotakis; D.Papageorgiou; A.Moutsatsou

    2006-01-01

    The present study investigates glass and cement compatibility with a view to use glass as a cement replacement. Amber, flint and green glasses were chosen due to their prevalence in the Greek market as packaging materials. The factors under investigation were the pozzolanicity of the glass cullet, the hydration rate and the mechanical strength development of the cement pastes, as well as the expansion of the specimens due to alkali-silica reaction.Moreover, the potential enhancement of glass pozzolanic activity was examined. The results of the study were encouraging to show the potentiality of utilising glass cullet in cementitious products.

  5. Operating experience with KRAFTWERK UNION cementation line

    International Nuclear Information System (INIS)

    A facility is described designed for fixation in a cement matrix of the radioactive concentrate produced by thickening waste water from the Bohunice nuclear power plant. The cementation line output is 0.6 m3 concentrate/h. The concentrate is put in 200 l drums. The individual operating units, cement management, air conditioning, dosimetric monitoring and the building part are described. The requirements for the operators and the assessment of the quality of raw materials and the product are discussed. (M.D.). 3 figs., 4 refs

  6. ULTRA-LIGHTWEIGHT CEMENT

    International Nuclear Information System (INIS)

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Issues, Task 2: Review Russian Ultra-Lightweight Cement Literature, Task 3: Test Ultra-Lightweight Cements, and Task 8: Develop Field ULHS Cement Blending and Mixing Techniques. Results reported this quarter include: preliminary findings from a literature review focusing on problems associated with ultra-lightweight cements; summary of pertinent information from Russian ultra-lightweight cement literature review; laboratory tests comparing ULHS slurries to foamed slurries and sodium silicate slurries for two different applications; and initial laboratory studies with ULHS in preparation for a field job

  7. Practical clinical considerations of luting cements: A review.

    Science.gov (United States)

    Lad, Pritam P; Kamath, Maya; Tarale, Kavita; Kusugal, Preethi B

    2014-02-01

    The longevity of fixed partial denture depends on the type of luting cement used with tooth preparation. The clinician's understating of various cements, their advantages and disadvantages is of utmost importance. In recent years, many luting agents cements have been introduced claiming clinically better performance than existing materials due to improved characteristics. Both conventional and contemporary dental luting cements are discussed here. The various agents discussed are: Zinc phosphate, Zinc polycarboxylate, Zinc oxide-eugenol, Glass-ionomer, Resin modified GIC, Compomers and Resin cement. The purpose of this article is to provide a discussion that provides a clinical perspective of luting cements currently available to help the general practitioner make smarter and appropriate choices. How to cite the article: Lad PP, Kamath M, Tarale K, Kusugal PB. Practical clinical considerations of luting cements: A review. J Int Oral Health 2014;6(1):116-20. PMID:24653615

  8. 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%

  9. Mesoscale texture of cement hydrates.

    Science.gov (United States)

    Ioannidou, Katerina; Krakowiak, Konrad J; Bauchy, Mathieu; Hoover, Christian G; Masoero, Enrico; Yip, Sidney; Ulm, Franz-Josef; Levitz, Pierre; Pellenq, Roland J-M; Del Gado, Emanuela

    2016-02-23

    Strength and other mechanical properties of cement and concrete rely upon the formation of calcium-silicate-hydrates (C-S-H) during cement hydration. Controlling structure and properties of the C-S-H phase is a challenge, due to the complexity of this hydration product and of the mechanisms that drive its precipitation from the ionic solution upon dissolution of cement grains in water. Departing from traditional models mostly focused on length scales above the micrometer, recent research addressed the molecular structure of C-S-H. However, small-angle neutron scattering, electron-microscopy imaging, and nanoindentation experiments suggest that its mesoscale organization, extending over hundreds of nanometers, may be more important. Here we unveil the C-S-H mesoscale texture, a crucial step to connect the fundamental scales to the macroscale of engineering properties. We use simulations that combine information of the nanoscale building units of C-S-H and their effective interactions, obtained from atomistic simulations and experiments, into a statistical physics framework for aggregating nanoparticles. We compute small-angle scattering intensities, pore size distributions, specific surface area, local densities, indentation modulus, and hardness of the material, providing quantitative understanding of different experimental investigations. Our results provide insight into how the heterogeneities developed during the early stages of hydration persist in the structure of C-S-H and impact the mechanical performance of the hardened cement paste. Unraveling such links in cement hydrates can be groundbreaking and controlling them can be the key to smarter mix designs of cementitious materials. PMID:26858450

  10. Microstructure Analysis of Heated Portland Cement Paste

    OpenAIRE

    Q. Zhang; Ye, G.

    2011-01-01

    When a concrete structure is exposed to high temperature, the mechanical damage and chemical transformation take place simultaneously, which will change the microstructure of material. On the other hand, the mechanical properties and transport properties depend on the development of microstructure of cement paste. In order to study the microstructure changes at high temperature, in this contribution the cement paste samples were firstly heated to varied temperatures from 100 °C to 1000 °C wit...

  11. Topics in Cement and Concrete Research

    OpenAIRE

    Brouwers, H. J. H.

    2006-01-01

    The present paper addresses several topics in regard to the sustainable design and use of concrete. First, major features concerning the sustainable aspects of the material concrete are summarised. Then the major constituent, from an environmental point of view, cement is discussed in detail, particularly the hydration and application of slag cement. The intelligent combining of mineral oxides, which are found in clinker, slag, fly ashes etc., is designated as mineral oxide engineering. It re...

  12. Stiffness and strength of composite acrylic bone cements

    Directory of Open Access Journals (Sweden)

    I. Knets

    2007-01-01

    Full Text Available Purpose: Different acrylic bone cements based upon PMMA-MMA system are applicable for implant fixation inbone tissue. The aim of present study is the optimisation of the structure of some new bone acrylic cements madeon the basis of PMMA-ethylmethacrylate-triethyleneglycoldimethacrylate and bone cements having additives (HAand radio pacifier, and the finding of the effect of these modifications on the flexural strength and stiffness.Design/methodology/approach: Different new bone cements on the basis of PMMA-EMA-TEGDMA system(ABC were developed experimentally. The stiffness and strength of the samples of these modified cements weredetermined in the special three point bending equipment.Findings: A comparison of the flexural properties of new PMMA-EMA-TEGDMA cements and commercialavailable PMMA-MMA cement showed that commercial bone cement had larger values of ultimate strengthand modulus of elasticity, but the difference is not very important. As concerns the polymerisation peaktemperature, then there is a significant difference between commercial PMMA-MMA cement (~ 800C andPMMA-EMA-TEGDMA modified cements (50 – 600C. The introduction of 10% and 18% of HA into solidphase does not influence essentially strength and modulus of elasticity of the PMMA-EMA-TEGDMA bonecements. The introduction of radio pacifier BaSO4 into bone cement leads to flexural strength diminishing.Low polymerisation peak temperature and appropriate mechanical properties of bone cements developed allowsregarding new 3-D structure acrylic bone cements as promising biomaterials.Research limitations/implications: It is supposed to carry out animal testing to learn more about reaction ofmodified implanted material on the biological environment.Practical implications: The new materials could be efficiently used as bone cements because they will notdamage surrounding biological tissue during curing.Originality/value: Paper is providing the new information about possibilities to

  13. [Microbial settlement of paint- and building-materials in the sphere of drinking water. 9. Communication: experimental examination of cement mortar for the lining with tiles (author's transl)].

    Science.gov (United States)

    Schoenen, D; Thofern, E

    1981-12-01

    The observation of a microbial growth in form of macrocolonies upon the joints of a tiled drinking water reservoir caused the microbiological testing of different pure mineral and some plastic containing cement mortar. Besides the conditions allowing the growth of macrocolonies on tiled plates with a construction like in a reservoir were examined.

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

    Directory of Open Access Journals (Sweden)

    Marcos O. de Paula

    2009-06-01

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

  15. EFFECT OF SHRINKAGE REDUING ADMIXTURE ON HYDRATION AND PORE STRUCTURE OF CEMENT-BASED MATERIALS%减缩剂对水泥基材料水化和孔结构的影响

    Institute of Scientific and Technical Information of China (English)

    张志宾; 徐玲玲; 唐明述

    2009-01-01

    The effect of shrinkage reducing admixture (SPA) on hydration process and pore structure of cement-based materials was studied. The hydration heat, chemically combined water and Ca(OH)2 content of cement paste and pore structure of mortar were measured by isothermal calorimeter, gravimetric method, X-ray diffraction and mercury intrusion porosimetry. The results indicate that the SPA has a slight retarding effect on hydration of cement, and the hydration of paste with and without the SPA tended to be the same with increasing the curing time. The appearance time of exothermic peak can be delayed, and the peak value as well as the hydration heat of cement can be lowered by adding the SPA. The chemically combined water of the SPA paste is less than that of the controlled sample. A difference of hydration between the controlled paste and the SPA paste is shortened with hydration age. The Ca(OH)2 content of the SPA paste is less than that of the controlled paste at 3 d, but they are similar at 28 d. Furthermore, the pore volume can be reduced and the innocuous pores can be increased by the SPA used. In addition, the resultant formation of the SRA in pore solution of cement-based materials was supposed.%通过对水泥净浆水化放热量、Ca(OH)2的含量和化学结合水量及水泥砂浆的孔结构的测定,研究减缩剂对水泥基材料水化和孔结构的影响.结果表明:减缩剂会延缓水泥的水化,且随着龄期的发展,延缓作用渐弱.具体表现为减缩剂会降低水泥水化放热的峰值,延迟峰值出现的时间,减小水化放热量;减缩剂能够减小水泥净浆的化学结合水量;龄期为3d时,掺减缩剂的净浆中Ca(OH)2的含量明显低于空白样的,28d时与空白样的相当;减缩剂能够减小水泥砂浆中多害孔和有害孔的孔体积,增加无害孔的孔体积.另外还对减缩剂在水泥基材料中存在的形态提出设想.

  16. Silica Transport and Cementation in Quartz Aggregates

    Science.gov (United States)

    Pebble, C.; Farver, J.; Onasch, C.; Winslow, D.

    2008-12-01

    Silica transport and cementation in quartz aggregates have been experimentally investigated. Starting materials include a natural quartz arenite (Pocono sandstone), sized clasts of synthetic quartz, and sized grains of disaggregated natural sandstones. Experimental charges consisted of amorphous silica powder (~25 mg), AlCl3 powder (~3 mg), 25 wt% NaCl brine solution (~20 mg), and the starting material (~150 mg). The charges were weld-sealed in gold capsules and run in cold-seal pressure vessels at 300°C to 600°C at 150 MPa confining pressure for up to 4 weeks. Detailed calibrations of the furnaces indicate the maximum temperature variation across the length of the sample charges (3-7mm) was vacuum impregnated with epoxy containing a blue dye and sawn in half along the long axis of the sample charge. The nature and amount of silica transport and cementation in the samples was determined by a combination of Cathodoluminescence (CL), Light Microscopy (LM), and Scanning Electron Microscopy (SEM). Photomosaics of the samples were collected and the amount of cement, porosity, and average grain sizes were determined by point-counting. The cement was easily recognized from the quartz grains by the difference in luminescence. The experiments indicate that the presence of amorphous silica results in rapid silica cementation in quartz aggregates (e.g., up to 12% cement by volume in 4 weeks at 450°C). The amount of cementation is a function of substrate type, time, temperature, and ionic strength of the brine. The rate of silica transport through the length of the experimental charge appears to be limited by the silica solubility and its rapid depletion by cementation. Although most of the cement was derived from the amorphous silica, evidence for local dissolution-precipitation was observed. The experiments demonstrate that the mobility of silica, and consequent precipitation of cement, does not require a temperature or pressure gradient as is commonly assumed. Rather

  17. Reinforcement of osteosynthesis screws with brushite cement.

    Science.gov (United States)

    Van Landuyt, P; Peter, B; Beluze, L; Lemaître, J

    1999-08-01

    The fixation of osteosynthesis screws remains a severe problem for fracture repair among osteoporotic patients. Polymethyl-methacrylate (PMMA) is routinely used to improve screw fixation, but this material has well-known drawbacks such as monomer toxicity, exothermic polymerization, and nonresorbability. Calcium phosphate cements have been developed for several years. Among these new bone substitution materials, brushite cements have the advantage of being injectable and resorbable. The aim of this study is to assess the reinforcement of osteosynthesis screws with brushite cement. Polyurethane foams, whose density is close to that of cancellous bone, were used as bone model. A hole was tapped in a foam sample, then brushite cement was injected. Trabecular osteosynthesis screws were inserted. After 24 h of aging in water, the stripping force was measured by a pull-out test. Screws (4.0 and 6.5 mm diameter) and two foam densities (0.14 and 0.28 g/cm3) were compared. Cements with varying solid/liquid ratios and xanthan contents were used in order to obtain the best screw reinforcement. During the pull-out test, the stripping force first increases to a maximum, then drops to a steady-state value until complete screw extraction. Both maximum force and plateau value increase drastically in the presence of cement. The highest stripping force is observed for 6.5-mm screws reinforced with cement in low-density foams. In this case, the stripping force is multiplied by 3.3 in the presence of cement. In a second experiment, cements with solid/liquid ratio ranging from 2.0 to 3.5 g/mL were used with 6.5-mm diameter screws. In some compositions, xanthan was added to improve injectability. The best results were obtained with 2.5 g/mL cement containing xanthan and with 3.0 g/mL cements without xanthan. A 0.9-kN maximal stripping force was observed with nonreinforced screws, while 1.9 kN was reached with reinforced screws. These first results are very promising regarding screw

  18. 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.

  19. Contamination effects of drilling fluid additives on cement slurry

    Directory of Open Access Journals (Sweden)

    Youzhi Zheng

    2015-10-01

    Full Text Available During the cementation of deep wells, contamination at the contact surface between cement slurry and drilling fluid will present a technical challenge, which may threaten operation safety. To deal with the problem, lab tests and analysis were performed specifically on the compatibility of fluids during cementation in Sichuan and Chongqing gas fields. Impacts of commonly used additives for drilling fluids were determined on fluidity and thickening time of conventional cement slurry. Through the infrared spectrum analysis, SEM and XRD, infrared spectrum data of kalium polyacrylamide (KPAM and bio-viscosifier were obtained, together with infrared spectrum, SEM and XRD data of cement slurry with additives. Contamination mechanisms of the cement slurry by conventional additives for drilling fluid were reviewed. Test results show that both KPAM and bio-viscosifier are such high-molecular materials that the long chains in these materials may easily absorb cement particles in the slurry to form mixed network structures; as a result, cement particles were prone to agglomeration and eventually lost their pumpability. Finally, assessment of and testing methods for the contamination effects of drilling fluid additives on cement slurry were further improved to form standards and codes that may help solve the said problems. This study will provide technological supports for the preparation of drilling fluids with desirable properties prior to cementation, the selection of optimal drilling fluids additives, and the development of innovative drilling fluids additives.

  20. Review of technologies for mercury removal from flue gas from cement production processes

    DEFF Research Database (Denmark)

    Zheng, Yuanjing; Jensen, Anker Degn; Windelin, Christian;

    2012-01-01

    kilns.Among the mercury control technologies, sorbent injection upstream of a particulate control device has shown the most promise. Due to material recirculation, and high moisture level in the cement kiln flue gas the application of sorbent injection to cement plants will be more challenging......Mercury is a pollutant of concern and mercury emissions from cement plants are under environmental regulation. After coal-fired power plants, mercury emissions from cement and mineral production are the second largest anthropogenic sources. Compared to fuels, cement raw materials are the major...... sources of mercury in the cement kiln flue gas. Cement plants are quite different from power plants and waste incinerators regarding the flue gas composition, temperature, residence time, and material circulation. Cement kiln systems have some inherent ability to retain mercury in the solid materials due...

  1. 水泥基材料早龄期相关概念研究与分析%Study and analysis on the related concepts of cement-based materials at early ages

    Institute of Scientific and Technical Information of China (English)

    黄杰; 徐轶安

    2015-01-01

    水泥基材料早龄期缺乏体积稳定性,是其非受力开裂的主要原因之一。在水泥基材料早龄期特性研究中,相关概念未有公认的定义,不同研究者的结论缺乏可比性和统计学意义,限制其深入研究。文中以相关文献中的成果进行对比分析,提出了水泥基材料早龄期的界定、早龄期收缩的分类以及自收缩与热膨胀的相互关系。%For cement-based materials at early ages,the lack of volume stability is one of the main rea-sons for non-stress cracking.In cement-based materials property research at early ages,some relevant concept definitions have not been accepted by researchers.The conclutions by different researchers lare ack of comparability and statistical significance,so the futher research is limited.The results about con-cept definitions in related literature have been comtrasted and analysed in this paper.The definition of cement-based materials at early ages,the classification of early age shrinkage,the relationsip between autogenous shrinkage and thermal expansion have been elaborated.

  2. Calcium phosphate cements properties with polymers addition

    International Nuclear Information System (INIS)

    Calcium phosphate cements (CPC) have attracted great interest to use in orthopedics and dentistry as replacements for damaged parts of the skeletal system, showing good biocompatibility and osseointegration, allowing its use as bone graft. Several studies have shown that the addition of polymer additives have a strong influence on the cement properties. The low mechanical strength is the main obstacle to greater use of CPC as an implant material. The objective of this study was to evaluate properties of a cement based on α-tricalcium phosphate (α-TCP), added polymers. PVA (10%, 8%, 6%), sodium alginate (2%) and polyacrylate ammonia (3%), all in weight, were added to the synthesized α-TCP powder. The samples were molded and evaluated for density, porosity in vitro test (Simulated Body Fluid), crystalline phases and mechanical strength. The results show increased the mechanical properties of the cement when added these polymers

  3. Curing time effect on the fraction of 137Cs from cement-ion exchange resins-bentonite clay composition

    Directory of Open Access Journals (Sweden)

    Plećaš Ilija

    2010-01-01

    Full Text Available To assess the safety of disposal of radioactive waste material in cement, curing conditions and time of leaching radionuclides 137Cs have been studied. Leaching tests in cement-ion exchange resins-bentonite matrix, were carried out in accordance with a method recommended by IAEA. Curing conditions and curing time prior to commencing the leaching test are critically important in leach studies since the extent of hydration of the cement materials determines how much hydration product develops and whether it is available to block the pore network, thereby reducing leaching. Incremental leaching rates Rn[cm/d] of 137Cs from cement-ion exchange resins-bentonite matrix after 240 days were measured. The results presented in this paper are examples of results obtained in a 30-year concrete testing project which will influence the design of the engineer trenches system for future central Serbian radioactive waste storing centre.

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

    OpenAIRE

    Antanas Kaziliunas

    2014-01-01

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

  5. Modifications induced by adding natural zeolitic pozzolans to cement paste

    OpenAIRE

    Blanco-Varela, M. T.; Martínez-Ramírez, S.; Gener, M.; Vázquez, T.

    2005-01-01

    Volcanic pozzolans owe their pozzolanic activity chiefly to the presence of vitreous or zeolitic material rich in SiO2, and Al20y compounds that react with the portlandite produced during cement hydration to generate amorphous gels with cementitious properties. The present study analyzes the modifications taking place in the composition, structure and micro structure of the hydra ted cement paste when 20% of the cement by we...

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

    Directory of Open Access Journals (Sweden)

    S Prakasam

    2014-01-01

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

  7. 水泥基复合材料氯离子扩散系数与孔隙率之间的关系%Relationship between porosity and chloride diffusivity in cement-based composite materials

    Institute of Scientific and Technical Information of China (English)

    高礼雄; 孙国文; 张云升; 孙伟

    2012-01-01

    For investigating the effect of porosity in cement-based composite materials on diffusion coefficient of chloride ion,a series of mortar specimens with different water-cement ratios,different volume fractions and different diameters and graduation of aggregates are cast,and then chloride diffusivity of mortar specimens are measured by steady-state electric acceleration method and pore structure parameters of corresponding samples are obtained by mercury intrusion porosimetry.At the same time,the pore size distributions are visualized by X-ray micro-focus computer tomography.The results show that porous interfacial transition zones between aggregate and bulk cement paste significantly change the distribution of pore structure in hardened cement paste,and the smaller water-cement ratio is,the more significant the effect of interfacial transition zones on pore structures of hardened cement paste is.A good correlation between the total porosity,capillary porosity and the diffusion coefficient of chloride ion in cement-based composite materials has been determined and the continuous pore diameter is linearly related to the diffusion coefficient of those.Furthermore,the larger the continuous pore diameter is,the larger the value of chloride diffusivity is.%为了研究水泥基复合材料中孔隙率对氯离子扩散系数的影响,成型了不同水灰比,含骨料体积分数、粒径与级配不同的砂浆试样;采用稳态电加速法测试氯离子扩散系数、压汞技术测试孔结构参数、微焦点计算机断层扫描技术(X-CT)可视化孔结构分布,系统地研究了水泥基复合材料氯离子扩散系数与其骨料体积分数、总孔隙率、毛细孔隙率、连通孔径之间的关系。结果表明:骨料与基体之间的界面过渡区(界面区)显著地改变了水泥石中孔结构分布,水灰比越小,多孔的界面区对材料孔隙率的影响越显著;水泥基复合材料的氯离子扩散系数与其总孔隙、

  8. Low-cycle fatigue of surgical cements

    Directory of Open Access Journals (Sweden)

    A. Balin

    2007-01-01

    Full Text Available Purpose: In case when surgical cement is used to fix endoprostheses of joints the fatigue character of mechanicalinterraction in the cement seems to be a significant importance. The paper suggests to adapt the research methodof low cycle fatigue for modelling the loads on surgical cements in an artificial hip joint. Surgical cements havealso been modified in order to improve their functional properties.Design/methodology/approach: Low cycle fatigue tests were conducted on samples made from Palamedcement without an addition and on samples modified with glassy carbon and titanium. The tests were conductedon a servohydraulic fatigue testing machine, MTS-810, with displacement control.Findings: Fatigue tests proved viscoelastic character of all the tested materials. During the fatigue tests, thephenomenon of stress cyclic relaxation was observed.Research limitations/implications: Modelling the loadings of cement in endoprostheses of joints with the lowcycle fatigue method takes into account all high value stresses, while cement is being used for endoprosthesesfor many years in the conditions of random stress and deformation courses. Therefore the obtained stress anddeformation values are bigger than those which would have been obtained in real conditions in the same time.Practical implications: The low cycle fatigue tests carried out showed how important is the factor of timefor the behavior of surgical cement in the conditions of changeable loadings. This fact is essential to assessits usability for endoprosthesoplasty of joints, specially of a hip joint. Post deformation return which is acharacteristic feature for material viscoelasticity enables its regeneration conditioning expected durability ofendoprosthesis of joints.Originality/value: Low cycle fatigue testing method for modelling of loads on surgical cement in artificial hipjoint enables to carry out the tests in a shorter period of time.

  9. 地聚合物水泥路面快速修补材料性能研究%Study on the Properties of Geopolymer Concrete Using as Rapid Repair Materials for Cement Pavement

    Institute of Scientific and Technical Information of China (English)

    常利; 艾涛; 延西利; 吕霖; 杨慧成

    2014-01-01

    针对水泥路面修补后开放交通时间偏长、耐久性较差和施工工艺复杂的问题,采用固体复合激发剂、粉煤灰和偏高岭土及其他外加剂制备一种地聚合物水泥快速修补材料,并对其混凝土力学性能、界面粘结性能、收缩率、抗冻性能进行测试.结果表明,当掺入10%的复合激发剂和10%的普通硅酸盐水泥时,地聚合物水泥的早期力学性能达到最优,所制备的地聚合物水泥混凝土修补材料具有快凝早强和优良的耐久性等特点,扫描电子显微镜(SEM)微观分析表明,由于碱激发反应和未激发粉煤灰的填充效应,地聚合物水泥混凝土具有致密的微观结构.%In order to solve long opening-to-traffic time,poor durability and complex process of concrete pavement repaired problem,a kind of rapid repair geopolymer material was prepared using the solid composite activator,fly ash,metakaolin and other admixtures.The properties of the working performance,mechanical properties,bonding performance between New and old Concrete,shrinkage,frost resistance of geopolymer-cement-concrete were tested.The experimental results show that with 10% compound activators and 10% ordinary Portland cement,the early mechanical properties of the geopolymer cement can achieve the optimal; the rapid repair geopolymer-cement-concrete has the advantages of quick setting early strength and excellent durability.The scanning electron microscopy (SEM) results indicatethat the geopolymer-cement-concrete has micro compact structure as the result of the filling effect of inactivated fly ash and alkali activated reaction.

  10. Replacement of asbestos cement fills in natural draft cooling towers

    Energy Technology Data Exchange (ETDEWEB)

    Gay, G.A.; Stackhouse, D.W.

    1986-01-01

    This paper describes some of the deterioration problems which have been encountered with asbestos cement materials, the environmental and regulatory problems associated with asbestos, and some of the concerns to be addressed replacing fill material in a natural draft tower.

  11. [Microbial settlement of paint- and building-materials in the sphere of drinking water. 5. Communication: Macrocolonies on the cement mortar lining in a water main (author's transl)].

    Science.gov (United States)

    Schoenen, D

    1980-09-01

    It is reported a microbial growth in form of macrocolonies on a cement mortar line in a potable water main. Simultaneously an increase of bacterial content in the water could be observed. The bacterial content could be reduced by chlorination, but the microbial growth on the surface of the lining was not suppressed. Macrocolonies could be observed the same as before at the last inspection 6 1/2 years after opening of the main.

  12. Modelisation of the growth of extended defects created by electron irradiation in CdTe

    International Nuclear Information System (INIS)

    After a brief review of the experimental features of dislocation loops created in cadmium telluride by high energy electron irradiation, we present a theoretical modelisation of the growth of extended defects. The basic method of the Chemical Reaction Rate Theory has been modified in order to take into account: the instability of small clusters, the effects of surfaces, the fact that CdTe is a binary compound. The comparison between theoretical and experimental results leads us to conclude that the vacancy-interstitial recombination energy (Ev) is different from the diinterstitial formation energy (Ei). The values of these energies have been determined: Ei=.35eV, Ev=.25eV, Ed=1.1eV (small clusters dissociation energy). This work has also shown that the lake of dislocation loops at high irradiation temperature (T>480K) is not only a thin film effect but is due to clusters instability

  13. Tympanoplasty with ionomeric cement

    DEFF Research Database (Denmark)

    Kjeldsen, A D; Grøntved, A M

    2000-01-01

    of > 10 dB, in 4 there was a slight improvement and in 2 a decline. The difference was not statistically significant. Hearing improvement using ionomeric cement in type II tympanoplasty was satisfactory. Reconstruction of the ossicular chain with ionomeric cement is recommended, as the procedure is easy...

  14. 不同胶凝材料的精细混凝土高温后力学性能%MECHANICAL PROPERTY OF FINE GRAINED CONCRETE WITH DIFFERENT CEMENTING MATERIAL AFTER EXPOSURE TO HIGH-TEMPERATURE

    Institute of Scientific and Technical Information of China (English)

    沈玲华; 王激扬; 徐世烺; 付晔

    2015-01-01

    为了改善用于纤维编织网增强混凝土基体材料的精细混凝土的耐高温性能,该文进行了120个40mim×40mm×160mm棱柱体的高温后抗折强度试验和240个40mm×40mm×40mm立方体的高温后抗压强度试验.考察了不同胶凝材料对精细混凝土试件高温后力学性能的影响,包括外掺纳米材料以及以高铝水泥作为主要胶凝材料的影响.结果表明:体积掺量为1.5%和3.0%纳米SiO2气凝胶粉末未能改善精细混凝十的耐高温性能,质量掺量为5.0%纳米陶瓷粉在目标温度TR=800℃时使基体混凝土的抗压和抗折强度分别提高84.2%和120.9%.当TR=800℃时,采用高铝水泥作为主要胶凝材料的试件力学性能均比普通精细混凝土试件大幅提高;各组掺入活性粉末的高铝水泥混凝土试件在TR=800℃时,相对抗压和抗折强度均比未掺活性粉末时有所提高.%To improve the high temperature resistance of fine grained concrete for textile reinforced concrete matrices,120 prism specimens (40mm×40mm×160mm) for flexural tests and 240 cube specimens (40mm×40mm×40mm) were prepared in this paper for compressive strength tests after exposure to high temperature.The effects of different cementing materials on mechanical properties of fine grained concrete were studied,including the effect of nanomaterial admixtures and the use of alumina cement as main cementing material.The results show that nanometer SiO2 aerogel powder cannot improve the high temperature resistance of fine grained concrete when volume fraction is 1.5% or 3.0%.Nanosized ceramic powder with quality content of 5.0% can improve the residual compressive and flexural strength of fine grained concrete by 84.2% and 120.9%,respectively,over that of concrete without nanosized ceramic powder at 800℃.When TR=800℃,mechanical properties of specimens with alumina cement as the main cementing material increase greatly compared with ordinary fine grained

  15. ULTRA-LIGHTWEIGHT CEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fred Sabins

    2002-01-23

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). This report includes results from laboratory testing of ULHS systems along with other lightweight cement systems: foamed and sodium silicate slurries. Comparison studies of the three cement systems examined several properties: tensile strength, Young's modulus, water permeability, and shear bond. Testing was also done to determine the effect that temperature cycling has on the shear bond properties of the cement systems. In addition, analysis was carried out to examine alkali silica reactivity of slurries containing ULHS. Data is also presented from a study investigating the effects of mixing and pump circulation on breakage of ULHS. Information is also presented about the field application of ULHS in cementing a 7-in. intermediate casing in south Texas.

  16. 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.).

  17. Interactions between cement grouts and sulphate bearing ground water

    International Nuclear Information System (INIS)

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

  18. Test on Sensor Effect of Cement Matrix Piezoelectric Composite

    Institute of Scientific and Technical Information of China (English)

    YANG Xiaoming; LI Zhongxian; DING Yang; LI Zongjin

    2005-01-01

    A novel cement matrix smart piezoelectric composite and its application as sensing element are presented.A cement matrix smart piezoelectric composite piece encapsulated in a cement mortar formed a practical sensor, and it was tested on material test system with cyclic loading.According to the theoretical analysis, the function of the cement matrix piezoelectric sensor output voltage was expressed in terms of the magnitude of the input cyclic loading amplitude and frequency.The curve fitting of gain function that is defined as sensor′s gain factor under different frequencies of input loading was carried out. From the results of curve fitting, it is found that the cement matrix smart piezoelectric composite has a simple relationship between input loading and output voltage.Therefore the cement matrix piezoelectric composite sensor is suitable to be applied in structural health monitoring.

  19. The Pore Structure and Hydration Performance of Sulphoaluminate MDF Cement

    Institute of Scientific and Technical Information of China (English)

    HUANG Cong-yun; YUAN Run-zhang; LONG Shi-zong

    2004-01-01

    The hydration and pore structure of sulphoaluminate MDF cement were studied by X-ray diffractometer ( XRD ), scanning electron microscope (SEM) and mercury intrusion porosimeter ( MIP ) etc. The ex-perimental results indicate that hydration products of the materials are entringites ( Aft ), aluminium hydroxide andCSH (Ⅰ) gel etc. Due to its very low water-cement ratio, hydration function is only confined to the surfaces of ce-ment grains, and there is a lot of sulphoaluminate cement in the hardenite which is unhydrated yet. Hydration re-action was rapidly carried under the condition of the heat-pressing. Therefore cement hydrates Aft, CSH (Ⅰ) andaluminium hydroxide gel fill in pores. The expansibility of Aft makes the porosity of MDF cement lower ( less than1 percent ) and the size of pore smaller (80 percent pore was less than 250A), and enhances its strength.

  20. Solidification of Spent Ion Exchange Resin Using ASC Cement

    Institute of Scientific and Technical Information of China (English)

    周耀中; 云桂春; 叶裕才

    2002-01-01

    Ion exchange resins (IERs) have been widely used in nuclear facilities. However, the spent radioactive IERs result in major quantities of low and intermediate level radioactive wastes. This article describes a laboratory experimental study on solidification processing of IERs using a new type of cement named ASC cement. The strength of the cementation matrix is in the range of 18-20 MPa (28 d); the loading of the spent IER in the cement-resin matrix is over 45% and leaching rates of 137Cs, 90Sr and 60Co are 7.92×10-5, 5.7×10-6, and 1.19×10-8 cm/d. The results show that ASC cement can be a preferable cementation material for immobilization of radioactive spent IER.

  1. 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.

  2. Modified-sulfur cements for use in concretes, flexible pavings, coatings, and grouts

    Science.gov (United States)

    McBee, W. C.; Sullivan, T. A.; Jong, B. W.

    1981-05-01

    A family of modified-sulfur cements was developed for the preparation of construction materials with improved properties. Various types of sulfur cements were prepared by reacting sulfur with mixtures of dicyclopentadiene and oligomers of cyclopentadiene. Durable cements were prepared with structural characteristics ranging from rigid to flexible. These cements were used to prepare corrosion-resistant materials for use in a wide variety of industrial applications where resistance to acidic and salt conditions is needed. These materials were prepared as rigid concretes, flexible pavings, spray coatings, and grouts. Production of modified-sulfur cements in a commercial-size plant was demonstrated.

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

  4. Portland Cement (KS and API Class G) and Relative Quantitative Analysis

    Science.gov (United States)

    LEE, Seung-Woo; CHAE, Gi-Tak; KIM, Taehee

    2015-04-01

    Portland cement is a common component consisting of a sealing material for wellbores for geological carbon storage to prevent vertical fluid migration and provide mechanical support. Portland cement was reacted with carbon dioxide (CO2) in supercritical, gaseous, and aqueous phases at various pressure and temperature conditions to simulate a cement-CO2 reaction along the wellbore from the carbon injection depth to the near surface. The reaction of the cement phase with CO2 can lead to important changes in its structure and properties. In this study, two types of cement were used: KS Portland cement and API Class G Portland cement. The hydrated cement sample columns (14 mm diameter X 90 mm long; water-to-cement ratio = 0.5) were reacted with CO2 in the saturated and the unsaturated condition. Fly-ash was used as additives to promote carbonation. These conditions were maintained under high pressure (8 MPa) and temperature (40 degree Celsius) for 10 and 100 days. To analyze the degree of carbonation after cement carbonation, relative quantitative analysis was proposed. And Rietveld method were conducted to evaluate a relative quantitative analysis (RQA) with an aragonite-calcite equation. This method can be an alternative to the general quantitative analysis method to identify the state of cement carbonation between Portland cement and CO2. Based on an understanding of cement carbonation and its relative quantification, we propose that our method should be used to select the optimized cement for CO2 storage. Using our method, KS (Korea Standard) Portland cement (type I) and API Class G Portland cement have been compared with respect to the characterization of each cement and to the cement carbonation of each cement.

  5. EFFECT OF NANOMATERIALS IN CEMENT MORTAR CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    WAIL N. AL-RIFAIE

    2016-09-01

    Full Text Available Concrete is considered as brittle materials and widely used due to high compressive strength but unfortunately having and has low tensile strength that has a numerous negative impacts on the lifespan of concrete made structures. Therefore, mechanical properties of cement mortar have been investigated experimentally using different types and ratios of nano material to improve the properties. Since the strength of the concrete is of high importance, different materials have been used to enhance the compressive and the tensile characteristics of the cement mortar compressive and tensile strength. Mainly, this objective has been implemented through using micro cement, micro sand, nano silica, and nano clay in developing a nano-cement mortar which can to improve the concrete for the constructional applications. The samples were prepared and tested under tensile and compressive mode according to ASTM-2011 regulations for concrete. The parameters that are taken consideration during the investigation were micro sand, micro cement, nano silica, developed nano clay, and naphthalene sulphonate as super- plasticizers. In general, it has been observed that the results showed a significant increase in both compressive and tensile strength of the mortar at early stages of hardening, where a maximum increase of 22% in the compressive strength was achieved , whereas 3.7 time increase in the compressive strength was recorded over the tradition levels of the concrete strength.

  6. In-situ Mechanical Manipulation of Wellbore Cements as a Solution to Leaky Wells

    Science.gov (United States)

    Kupresan, D.; Radonjic, M.; Heathman, J.

    2013-12-01

    Wellbore cement provides casing support, zonal isolation, and casing protection from corrosive fluids, which are essential for wellbore integrity. Cements can undergo one or more forms of failure such as debonding at cement/formation and cement/casing interface, fracturing and defects within cement matrix. Failures and defects within cement will ultimately lead to fluids migration, resulting in inter-zonal fluid migration and premature well abandonment. There are over 27,000 abandoned oil and gas wells only in The Gulf of Mexico (some of them dating from the late 1940s) with no gas leakage monitoring. Cement degradation linked with carbon sequestration can potentially lead to contamination of fresh water aquifers with CO2. Gas leaks can particularly be observed in deviated wells used for hydraulic fracking (60% leakage rate as they age) as high pressure fracturing increases the potential for migration pathways. Experimental method utilized in this study enables formation of impermeable seals at interfaces present in a wellbore by mechanically manipulating wellbore cement. Preliminary measurements obtained in bench scale experiments demonstrate that an impermeable cement/formation and cement/casing interface can be obtained. In post-modified cement, nitrogen gas flow-through experiments showed complete zonal isolation and no permeability in samples with pre-engineered microannulus. Material characterization experiments of modified cement revealed altered microstructural properties of cement as well as changes in mineralogical composition. Calcium-silicate-hydrate (CSH), the dominant mineral in hydrated cement which provides low permeability of cement, was modified as a result of cement pore water displacement, resulting in more dense structures. Calcium hydroxide (CH), which is associated with low resistance of cement to acidic fluids and therefore detrimental in most wellbore cements, was almost completely displaced and/or integrated in CSH as a result of

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

    Science.gov (United States)

    Walling, Sam A; Provis, John L

    2016-04-13

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

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

    Science.gov (United States)

    2011-05-17

    ... emission limits applicable to the Portland cement industry. See 75 FR 54970 (Sept. 9, 2010). The rule... that ``some Portland cement kilns combust secondary materials as alternative fuels''. 74 FR at 21138... as solid wastes or not) does not appreciably affect cement kilns' HAP emissions. 74 FR at...

  9. From Rocks to Cement. What We Make. Science and Technology Education in Philippine Society.

    Science.gov (United States)

    Philippines Univ., Quezon City. Science Education Center.

    This module deals with the materials used in making concrete hollow blocks. Topics discussed include: (1) igneous, metamorphic, and sedimentary rocks; (2) weathering (the process of breaking down rocks) and its effects on rocks; (3) cement; (4) stages in the manufacturing of Portland cement; and (5) the transformation of cement into concrete…

  10. POLYMER AND CEMENT MORTARS FOR THE CONSTRUCTION AND REPAIR OF BUILDINGS AND STRUCTURE

    Directory of Open Access Journals (Sweden)

    O. M. Pshinko

    2009-02-01

    Full Text Available In the article the analysis of polymer-cement mortars for their application in construction and repair of buildings and structures is presented. The main properties of known polymer-cement mortars used for this purpose are described. The advantages of application of polymer-cement mortars as repair materials are shown.

  11. Strength and Durability of Concrete: Effects of Cement Paste-Aggregate Interfaces, Part I: Theoretical Study on Influence of Interfacial Transition Zone on Properties of Concrete Materials

    OpenAIRE

    Zhang, Yiguo; Chen, Wai-Fah

    1998-01-01

    This research was based on a two-part basic research investigation studying the effects of cement paste-aggregate interfaces (or interfacial transition zones-HZ) on strength and durability of concrete. Part I dealt with the theoretical study and Part II dealt with the experimental. Part I, the theoretical part, illustrates the effect of ITZ on the concrete properties by assuming its elastic moduli to be varied continuously in the region. A four-phase composite model is employed and three func...

  12. 骨料对氯离子在水泥基复合材料中扩散系数的影响%Influence of Aggregates on Chloride Ion Diffusion Coefficient in Cement-Based Composite Materials

    Institute of Scientific and Technical Information of China (English)

    孙国文; 孙伟; 张云升; 刘志勇; 王彩辉

    2011-01-01

    To determine the influence of aggregates on chloride ion diffusion coefficient in cement-based composite materials, mortar and concrete specimens were cast with different aggregates, aggregate size distributions and aggregate volume fractions. Pore size distributions and chloride ion diffusion coefficients of the specimens were measured by mercury intrusion porosimetry test and steady-state accelerated migration test, respectively. The volume fraction of interracial transition zone (ITZ) could be calculated according to the mix proportions of specimens, size distribution of aggregates and ITZ thickness. The results show that the chloride diffusivity in cement-based composite materials is related to the chloride diffusion coefficient of matrix and ITZ, volume fraction of aggregate and ITZ. The volume fraction of ITZ is affected by the aggregate size distribution, the volume fraction of aggregate and thickness of ITZ. The presence of aggregates in cement-based materials might modify the pore structure of hardened cement paste,and its dilution effect and tortuosity effect could reduce chloride transport properties. The special microstmctures of ITZ could increase chloride transport. The influence of ITZ could be dominant to chloride diffusion in cement-based materials. Based on the experimental and analytical results, the approximate chloride ion diffusion coefficient of ITZ is 13.26 or 18.45 times greater than the matrix migration coefficient for mortar or concrete, respectively.%为了确定骨料对氯离子在水泥基复合材料中扩散系数的影响,利用压汞技术和稳态电迁移法分别对含不同类型、不同粒径分布、不同体积分数骨料的砂浆和混凝土试样,进行了孔结构和氯离子扩散系数的测试,并根据试样配合比、骨料的粒径分布以及界面过渡区(简称界面区)厚度进行了界面区体积分数计算,最后提出了界面区有效扩散系数的预测模型.结果表

  13. Orthodontic Cements and Demineralization: An In Vitro Comparative Scanning Electron Microscope Study

    OpenAIRE

    Prabhavathi, V; Jacob, Josy; Kiran, M. Shashi; Ramakrishnan, Murugesan; Sethi, Esha; Krishnan, C S

    2015-01-01

    Background: Comparison of the demineralization potential of four luting cements, i.e. zinc phosphate, conventional glass ionomer cement (GIC), resin-modified GIC and acid modified composite resin. Materials and Methods: This study was conducted on 75 extracted premolar teeth, which were grouped into five, each group containing 15 teeth. Groups were non-banded control, teeth cemented with the above-mentioned cements. These were incubated at 37°C for 30 days in sealable plastic containers, afte...

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

    OpenAIRE

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

    2011-01-01

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

  15. Quantification of water content across a cement-clay interface using high resolution neutron radiography

    OpenAIRE

    Shafizadeh, A; Gimmi, Thomas; Van Loon, L.; Kaestner, A.; Lehmann, E; Mäder, Urs; Churakov, Sergey

    2015-01-01

    In many designs for radioactive waste repositories, cement and clay will come into direct contact. The geochemical contrast between cement and clay will lead to mass fluxes across the interface, which consequently results in alteration of structural and transport properties of both materials that may affect the performance of the multi-barrier system. We present an experimental approach to study cement-clay interactions with a cell to accommodate small samples of cement and clay. The cell des...

  16. Development of Production Technologies for Universal Hydraulic Cement (UHC)

    OpenAIRE

    Syal, Dr. S K

    2013-01-01

    It is based on our recent approaches of Modern construction materials utilizing existing wastes such as fly ashes slags and to save energies by technological developments.The article is essential in the direction of new materials called Durable Integral polymer-pigmented cement concretes. UHC is calcium aluminate cements with natural properties of durable earth materials. It is a step towards Research for Innovation in Indian Industries

  17. 水泥基浆材室内试验及其边坡加固应用研究%Laboratory Test of Cement Matrix Grouting Material and Its Application in Slope Reinforcement

    Institute of Scientific and Technical Information of China (English)

    黄晴; 饶军应; 谢涛; 刘强

    2015-01-01

    Slope is often associated with collapse, landslides, mudslides and other disasters, which is endangering the lives and property of the masses around the project seriously. It is significant to take a research on slope reinforcement. The slope stability can be reinforced by plunging the cement liquid into the fractured rock mass of the slope. The optimum mix ratio, physical and mechanical properties, initial setting time and final setting time of five different kinds of cement based grouting material were determined by the laboratory test. The equations pressure and diffusion radius of grouting were provided. The layout of grouting reinforcement was presented and put into effect on the base of a slope in Xu-Huai Highway. The reinforcement effect was verified by numerical simulation and field test. Results show: the physical and mechanical properties can be improved; the strength and bearing capacity of soil can be enhanced. It is practicable and remarkable for grouting reinforcement by the cement matrix comprised with cement, yellow ground and fly ash.%边坡常伴随崩塌、滑坡和泥石流等灾害,严重危害着工程周围群众的生命财产安全,研究边坡加固意义重大。将注浆液压入破碎边坡内部,通过对软弱岩土体的加固可提高边坡稳定性。通过室内试验,确定了5种水泥基注浆材料的最佳配比、物理力学性能和初凝终凝时间。在推导了注浆压力和注浆扩散半径的公式后,结合溆怀高速边坡加固工程实践,提出并实施了具体注浆加固方案。最后,通过数值模拟和现场检测对注浆加固效果进行了验证。结果表明:注浆改善了土层物理力学性质,提高了土体强度及承载力,水泥黄砂粉煤灰注浆加固切实可行,效果显著。

  18. Influence of Dosage of Blast-furnace Slag on Microstructure of Cement-based Materials%磨细矿渣掺量对水泥基复合材料微结构的影响

    Institute of Scientific and Technical Information of China (English)

    刘杰

    2013-01-01

    To determine the influence of blast-furnace slag on microstructure of cement-based materials and its the reasonable dosage, the harden hydrated cement with 10% -70% slag replacement at a fixed water to binder ratio of 0.48 was measured its porosity, pore size distribution, content of calcium hydroxide and non-e-vaporable water and the reaction degree of slag by using mercury intrusion porosimetry, backscattered electron microscopy, X-ray diffraction, thermogravimetry analysis-Differential Scanning Calorimetry and Chemical analysis methods. The results show that pore structure can be improved by adding slag even at high incorporating proportion. Comparatively speaking, the porosity of harden slag-cement paste is smallest under the conditions of the slag content in the range of 30% to 50 %. In addition, according to the non-evaporated water curve trend and the reaction degree of the slag, an optimum content can be obtained, that is the non-evaporated water content and the highest reaction degree of slag, when the slag is replaced with 30 per cement content.%利用压汞、背散射电镜、X射线衍射(XRD)和综合热分析以及化学测试手段系统研究了水胶比为0.48、矿渣掺量为10%~70%的硬化浆体中孔隙率、孔径分布、CH(OH)2(称简CH)含量、非蒸发水量和矿渣反应程度,以确定矿渣掺量对水泥基材料微结构的影响以及最佳掺量.结果表明:矿渣在大掺量情况下也能够改善浆体孔结构分布,相比较而言,矿渣掺量在30%~50%之间时浆体的孔隙率最小;非蒸发水曲线的变化趋势以及矿渣自身反应程度说明,在其掺量30%左右时,存在一个最佳掺量使非蒸发水含量和反应程度最高.

  19. Clinical application of temporary crown and cement materials: physical properties and biological safety%临时冠材料及黏结材料的临床应用:物理性能与生物安全性

    Institute of Scientific and Technical Information of China (English)

    聂二民; 姜瑞; 张春元; 曾尽娣; 谈济州

    2015-01-01

    背景:临时冠在临床应用较为广泛,临时冠及其黏结材料随着材料科学的发展不断更新,其临床应用、物理学性能及生物安全性方面也越来越优越.目的:综述临时冠及其黏结材料的临床应用现状、物理性能及生物安全性.方法:以"temporary crown,provisional crown,temporary restoration,provisional restoration,interim restoration"为英文检索词,应用计算机检索PubMed数据库中2004年1月至2014年12月发表的相关文章.纳入与临时冠及其黏结材料相关的研究文献,排除重复性研究.结果与结论:通过临床评价和实验研究得出,临时冠材料自身聚合收缩、聚合产热、单体释放等物理特性和细胞毒性、对软组织的刺激性等生物安全性方面是临床要克服的关键问题.临时冠材料和黏结材料在临床上应用广泛,随着新材料筛选和新制作方法的出现其具有巨大的应用前景和较高的临床价值,但在其实验室研究和临床应用的探索过程中,还有许多亟待解决和深入探究的问题.%BACKGROUND:Temporary crown has been used widely in clinic. The physical properties and biological safety of temporary crown and cement materials are more superior along with the development of material science. OBJECTIVE:To summarize clinical application, physical properties and biological safety of the temporary crown and cement materials. METHODS:PubMed database was searched by the key words of "temporary crown, provisional crown, temporary restoration, provisional restoration, interim restoration" in English to retrieve relevant articles published from January 2004 to December 2014. Literatures addressing the temporary crown and cement materials were included, and the repetitive researches were excluded. RESULTS AND CONCLUSION:Through the clinical evaluation and experimental study, the physical properties (polymerization shrinkage, polymerization heat production, polymerization monomer release) and

  20. 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

  1. Cytotoxicity evaluation of five different dual-cured resin cements used for fiber posts cementation

    Science.gov (United States)

    Dioguardi, M; Perrone, D; Troiano, G; Laino, L; Ardito, F; Lauritano, F; Cicciù, M; Muzio, L Lo

    2015-01-01

    Custom-cast posts and cores are usually used to treat endodontically treated teeth. However, several researches have underlined how these devices may be a much higher elastic modulus than the supporting dentine and the difference in the modulus could lead to stress concentrating in the cement lute, leading to failure. The role of the cement seems to play a fundamental role in order to transfer the strength during the chewing phases. Aim of this research is to record the rate of cytotoxicity of five different dual-cured resin cements used for fiber posts cementation. We tested the cytotoxicity of this five materials on MG63 osteoblast-like cells through two different methods: MTT ([3-4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide succinate) assay which tests for mitochondrial enzyme activity6 and xCELLigence® system. PMID:26309592

  2. 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.

  3. Development of nanosilica bonded monetite cement from egg shells

    International Nuclear Information System (INIS)

    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

  4. Alternative Fuels in Cement Production

    DEFF Research Database (Denmark)

    Larsen, Morten Boberg

    in particular is influenced by insufficient carbon burnout in the calciner system, which results in reducing conditions in the material inlet of the rotary kiln and consequently an increased tendency to form deposits induced by sticky eutectic melts. Clinker quality is mainly affected by minor components from...... a decisive influence on the fuel carbon burnout in cement kiln systems. The oxidation kinetics of a char from TDF was investigated experimentally and by mathematical modelling. Experiments were performed in a fixed bed reactor under well - iii - defined conditions, where small particles (102-212μm) of TDF...

  5. 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.

  6. 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%.

  7. Effective Permeability Change in Wellbore Cement with Carbon Dioxide Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Um, Wooyong; Jung, Hun Bok; Martin, Paul F.; McGrail, B. Peter

    2011-11-01

    Portland cement, a common sealing material for wellbores for geological carbon sequestration was reacted with CO{sub 2} in supercritical, gaseous, and aqueous phases at various pressure and temperature conditions to simulate cement-CO{sub 2} reaction along the wellbore from carbon injection depth to the near-surface. Hydrated Portland cement columns (14 mm diameter x 90 mm length; water-to-cement ratio = 0.33) including additives such as steel coupons and Wallula basalt fragments were reacted with CO{sub 2} in the wet supercritical (the top half) and dissolved (the bottom half) phases under carbon sequestration condition with high pressure (10 MPa) and temperature (50 C) for 5 months, while small-sized hydrated Portland cement columns (7 mm diameter x 20 mm length; water-to-cement ratio = 0.38) were reacted with CO{sub 2} in dissolved phase at high pressure (10 MPa) and temperature (50 C) for 1 month or with wet CO{sub 2} in gaseous phase at low pressure (0.2 MPa) and temperature (20 C) for 3 months. XMT images reveal that the cement reacted with CO{sub 2} saturated groundwater had degradation depth of {approx}1 mm for 1 month and {approx}3.5 mm for 5 month, whereas the degradation was minor with cement exposure to supercritical CO{sub 2}. SEM-EDS analysis showed that the carbonated cement was comprised of three distinct zones; the innermost less degraded zone with Ca atom % > C atom %, the inner degraded zone with Ca atom % {approx} C atom % due to precipitation of calcite, the outer degraded zone with C atom % > Ca atom % due to dissolution of calcite and C-S-H, as well as adsorption of carbon to cement matrix. The outer degraded zone of carbonated cement was porous and fractured because of dissolution-dominated reaction by carbonic acid exposure, which resulted in the increase in BJH pore volume and BET surface area. In contrast, cement-wet CO{sub 2}(g) reaction at low P (0.2 MPa)-T (20 C) conditions for 1 to 3 months was dominated by precipitation of micron

  8. Post cementation sensitivity evaluation of glass Ionomer, zinc phosphate and resin modified glass Ionomer luting cements under class II inlays: An in vivo comparative study

    Directory of Open Access Journals (Sweden)

    Chandrasekhar V

    2010-01-01

    Full Text Available Objective: This study aims to compare the patient-perceived post-cementation sensitivity of class II metal restorations preoperatively, immediately after cementation, one week after cementation and one month after cementation with (1 Glass Ionomer luting cement (2 Zinc Phosphate cement and (3 Resin-modified Glass Ionomer luting cement. Materials and Methods: A total of 60 patients, irrespective of sex, in the age group of 15-50 years were selected and the teeth were randomly divided into three groups of 20 each. Twenty inlay cast restorations were cemented with three different luting cements. The criteria adapted to measure tooth sensitivity in the present study were objective examination for sensitivity.(1 Cold water test (2 Compressed air test and (3 Biting pressure test. Results: The patients with restorations cemented with Resin-modified Glass ionomer demonstrated the least postoperative sensitivity when compared with Glass Ionomer and zinc phosphate cement at all different intervals of time evaluated by different tests. Conclusion: The patients with restorations cemented with resin-modified Glass ionomer demonstrated the least postoperative sensitivity.

  9. Expansion control for cementation of incinerated ash

    International Nuclear Information System (INIS)

    A method, in which incinerated ash is solidified with a cement material, has been developed to dispose of radioactive incinerated ash waste. A small amount of metallic Al, which was not oxidized in the incineration, existed in the ash. When such ash was mixed with a cement material and water, alkaline components in the ash and the cement were dissolved in the mixing water and then metallic Al reaction with the alkaline compounds resulted in generation of H2. Because the H2 generation began immediately just after the mixing, H2 bubbles pushed up the mixed grout material and an expanded solidified form was obtained. The expansion leads to lowering the strength of the solidified form and making harmful void. In this study, we tried to control H2 generation from the reaction of metallic Al in the cementation by means of following two methods, one was a method to let metallic Al react prior to the cementation and the other was a method to add an expansion inhibitor that made an oxide film on the surface of metallic Al. In the pre-treatment, the ash was soaked in water in order to let metallic Al react with it, and then the ash with the immersion solution was dried at 105 Celsius degrees. The pre-treated ash was mixed with an ordinary portland cement and water. The inhibitor of lithium nitrite, sodium nitrite, phosphoric acid, or potassium dihydrogen phosphate was added at the mixing process. The solidified forms prepared using the pre-treated ash and lithium nitrite were not expanded. Phosphoric acid and sodium nitrite were effective for expansion control, but potassium dihydrogen phosphate did not work. (authors)

  10. Modelling of the mechanical behaviour of a material containing spherical cavities under pressure; example of the aging of a metal tritide; Modelisation du comportement mecanique d'un materiau contenant des cavites sous pression; cas du vieillissement d'un tritiure metallique

    Energy Technology Data Exchange (ETDEWEB)

    Chalon, F

    2001-07-01

    The study aims at modeling the mechanical behaviour of a material containing spherical cavities under pressure (bubbles) of nano-metric size. This work deals with research on tritium storage in metals. In this way, metal tritides are obtained. During time, helium is generated by tritium decay. Helium appears as a gas, which forms bubbles in the metal tritide. These bubbles subsequently cause damage within the material. The purpose of this work was therefore the following: (i) to determine the overall elastic moduli as a function of the volume fraction of cavities. thus providing an information about material damage, (ii) to analyze the macroscopic inflation of the material in order to solve storage problems, (iii) to determine the local stress fields for predicting the evolutions of the bubbles and the matrix. With the help of the scale change methods (homogenization) the macroscopic mechanical properties of the material can be determined as a function of its morphology on a microscopic scale. Thus the damage of the material can be estimated by experimental measurements of the global elastic moduli. Homogenization also allows the elastic inflation to be evaluated as well as the effects of cavity clusters and local variations of the elastic moduli. The internal stresses are determined on the microscopic scale (cavity scale). Two analytical methods (Eshelby-Mura and Legendre polynomials) and one numerical approach (Abaqus) are used to obtain more information and a best description of the material. It is shown that bubbles should attain the same size and same pressure and the plastic strain zones are determined. (author)

  11. 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

  12. Surface characterization of the cement for retention of implant supported dental prostheses: In vitro evaluation of cement roughness and surface free energy

    International Nuclear Information System (INIS)

    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

  13. 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.

  14. Research And Development Of A Pilot First Generation PGNAA OFF-BELT System For Analysing Of Composition Of Cement And Bauxite Raw Material

    International Nuclear Information System (INIS)

    With purpose of development of the PGNAA system which can operate on the field in the condition of considerably changing of temperature and moisture, a multi channel analyzer-MCA 2k was designed and developed, which can compatibly operate with BGO detector, connected with computer through USB 2.0 port. Beside that, a software for obtaining and displaying the prompt gamma spectrum, with the spectrum stability function and convenience in the data was also designed and developed. The first generation PGNAA system was experimented in the changing condition of temperature in the laboratory. The result give out that the prompt gamma spectrum was stability during temperature changing, the peak area of the elements in the samples changed about 7%. Besides that, the first generation PGNAA system was also experimented to analyze the cement and bauxite samples. The result was also matched with the other analysis methods such as chemistry method and INAA method with the difference about 10%. (author)

  15. Effects of aggregate volume content on sulfate resistance properties of cement based materials with supplementary cementitious materials%集料含量对掺矿物掺合料水泥基材料抗硫酸盐侵蚀性能的影响

    Institute of Scientific and Technical Information of China (English)

    吴凯; 徐玲琳; 施惠生; 高云

    2016-01-01

    The degradation of cement-based materials with different aggregate volume contents and ad-ditions, was analyzed when they were exposed to 5 and 50 g/L Na2 SO4 at 20℃.The microstructures of the corresponding cement-based materials was determined by mercury intrusion porosimetry (MIP), scanning electron microscopy backscattered electron ( SEM-BSE) image, and energy dispersive spec-trum ( EDS) analysis.The influence mechanism of the mineral addition and the aggregate volume con-tent on the sulfate resistance properties of cement-based materials was investigated.Results show that the addition of limestone powder ( LP) causes an increase in the porosity of hardened paste, exerting an adverse effect on the sulfate-resistance ability of cement-based materials.The incorporation of high amount of slag increases the total porosity, but refines the slurry pore structure from coarse pore to fi-ner one (>10 nm) .Moreover, the addition of slag strengthens the sulfate-resistance ability of ce-ment-based materials significantly.After corrosion by Na2 SO4 , the degradation of cement-based mate-rials prepared with pure Portland cement or Portland cement-limestone powder binary binders is more severe as the aggregate volume content increases.However, this negative effect caused by the aggre-gate is less remarkable in case of the slag blended system.From the BSE image and EDS analysis, the preferable deposition of gypsum in the region close to the aggregate is the main reason for the expand-ed degradation of specimens with a relative high amount of aggregate.%对不同集料体积掺量及掺合料配制的水泥基材料在室温、Na2 SO4溶液浓度为5和50 g/L时的损伤破坏过程进行分析,并采用压汞法、扫描电镜背散射电子图像分析和能谱扫描等方法得到相应水泥基材料的微观结构,研究了矿物掺合料和集料含量对水泥基材料抗硫酸盐侵蚀性能的影响机理。结果表明:单掺石灰石粉造成的硬化浆体

  16. 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

  17. New modelling method for fast reactor neutronic behaviours analysis; Nouvelles methodes de modelisation neutronique des reacteurs rapides de quatrieme Generation

    Energy Technology Data Exchange (ETDEWEB)

    Jacquet, P.

    2011-05-23

    Due to safety rules running on fourth generation reactors' core development, neutronics simulation tools have to be as accurate as never before. First part of this report enumerates every step of fast reactor's neutronics simulation implemented in current reference code: ECCO. Considering the field of fast reactors that meet criteria of fourth generation, ability of models to describe self-shielding phenomenon, to simulate neutrons leakage in a lattice of fuel assemblies and to produce representative macroscopic sections is evaluated. The second part of this thesis is dedicated to the simulation of fast reactors' core with steel reflector. These require the development of advanced methods of condensation and homogenization. Several methods are proposed and compared on a typical case: the ZONA2B core of MASURCA reactor. (author) [French] Les criteres de surete qui regissent le developpement de coeurs de reacteurs de quatrieme generation implique l'usage d'outils de calcul neutronique performants. Une premiere partie de la these reprend toutes les etapes de modelisation neutronique des reacteurs rapides actuellement d'usage dans le code de reference ECCO. La capacite des modeles a decrire le phenomene d'autoprotection, a representer les fuites neutroniques au niveau d'un reseau d'assemblages combustibles et a generer des sections macroscopiques representatives est appreciee sur le domaine des reacteurs rapides innovants respectant les criteres de quatrieme generation. La deuxieme partie de ce memoire se consacre a la modelisation des coeurs rapides avec reflecteur acier. Ces derniers necessitent le developpement de methodes avancees de condensation et d'homogenisation. Plusieurs methodes sont proposees et confrontees sur un probleme de modelisation typique: le coeur ZONA2B du reacteur maquette MASURCA

  18. 低温硫酸盐侵蚀环境中水泥石腐蚀产物%EROSION SUBSTANCE OF CEMENT-BASED MATERIAL IN SULFATE ATTACK ENVIRONMENT AT LOW TEMPERATURE

    Institute of Scientific and Technical Information of China (English)

    张风臣; 马保国; 尹耿; 吴媛媛; 朱艳超

    2008-01-01

    研究了水胶比为0.45,掺35%石灰石粉水泥基材料标准养护28d后在(5±2)℃浸泡于SO2-4质量分数为3.38%的钠盐、镁盐、铝盐3种硫酸盐侵蚀溶液中15周时的破坏状况和强度损失率.采用Fourier红外光谱、X射线衍射、扫描电子显微镜、能谱以及Raman光谱确定水泥石腐蚀物相和组成.结果表明:镁盐溶液中试件抗压强度损失率最大,其次是钠盐溶液中试件,铝盐溶液中试件抗压强度损失率最小;钠盐溶液和铝盐溶液中水泥石主要腐蚀产物是钙矾石和石膏;镁盐溶液中水泥石主要腐蚀产物是钙矾石、石膏、碳硫硅酸钙和少量水镁石.%Cement-based material made at a water-binder ratio of 0.45, with 35% cement replacement ratio by limestone powder were cured under standard conditions for 28d and then immersed in three kinds of sulfate solutions (Na2SO4, MgSO4, Al2(SO4)318H2O) with 3.38% mass fraction of SO2-4 for 15 weeks at (5±2)℃. Exterior attack and ratio of compressive strength loss were studied, and ero-sion substances of cement-based material were investigated by means of Fourier transform infrared spectroscopy, X-ray diffraction,scanning electron microscopy, and energy dispersive spectrum as well as Raman spectra. The results show that the ratio of compres-sive strength loss in MgSO4 solution is the greatest, and that in Al2(SO4)318H2O solution is the lowest among these three kinds of sulfate solutions. In Na2SO4 and Al2(SO4)3?18H2O sulfate solutions, the main erosion substances are ettringite and gypsum. And in MgSO4 sulfate solution the main erosion substances are ettringite, gypsum, thaumasite and brucite.

  19. Alternative Fuel for Portland Cement Processing

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-30

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

  20. Alternative Fuel for Portland Cement Processing

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-30

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

  1. Microbial-influenced cement degradation: Literature review

    International Nuclear Information System (INIS)

    The Nuclear Regulatory Commission stipulates that disposed low-level radioactive waste (LLW) be stabilized. Because of apparent ease of use and normal structural integrity, cement has been widely used as a binder to solidify LLW. However, the resulting waste forms are sometimes susceptible to failure due to the actions of waste constituents, stress, and environment. This report reviews literature which addresses the effect of microbiologically influenced chemical attack on cement-solidified LLW. Groups of microorganisms are identified, which are capable of metabolically converting organic and inorganic substrates into organic and mineral acids. Such acids aggressively react with concrete and can ultimately lead to structural failure. Mechanisms inherent in microbial-influenced degradation of cement-based material are the focus of this report. This report provides sufficient evidence of the potential for microbial-influenced deterioration of cement-solidified LLW to justify the enumeration of the conditions necessary to support the microbiological growth and population expansion, as well as the development of appropriate tests necessary to determine the resistance of cement-solidified LLW to microbiological-induced degradation that could impact the stability of the waste form

  2. Pore structure in blended cement pastes

    DEFF Research Database (Denmark)

    Canut, Mariana Moreira Cavalcanti

    Supplementary cementitious materials (SCMs), such as slag and fly ash, are increasingly used as a substitute for Portland cement in the interests of improvement of engineering properties and sustainability of concrete. According to studies improvement of engineering properties can be explained...... supplement each other. Cement pastes (w/b=0.4) with and without slag and fly ash cured at two moisture (sealed and saturated) and temperature (20 and 55ºC) conditions were used to investigate the combined impact of SCMs addition and curing on the pore structure of pastes cured up to two years. Also...... volume and threshold pore size were found when comparing with plain cement paste at the same curing conditions. The porosity methods MIP, LTC and SEM have been shown to be suitable to characterise pore parameters of the pastes. MIP is a simple and fast method which covers a large range of pore sizes...

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

    OpenAIRE

    Barney, Christopher W; Erk, Kendra

    2013-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Folagbade S.O.

    2016-03-01

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

  5. Microstructural and Mechanical characterization of WC-Co cemented carbides

    OpenAIRE

    Zakia, Rizki

    2013-01-01

    WC-Co cemented carbides are ceramic-metal composite materials made of carbides embedded in a metal phase that acts as a binder. They exhibit an exceptional combination of strength, toughness and wear resistance as a result of the extremely different properties of their two constitutive phases. Consequently, cemented carbides have been positioned as suitable options when selecting materials for tribomechanical applications, and their implementation continues to gain a place in t...

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

    OpenAIRE

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

    2015-01-01

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

  7. In-situ monitoring of early-age electrical resistivity change process of cement-based materials%原位监测水泥基材料早期电阻率的变化过程

    Institute of Scientific and Technical Information of China (English)

    刘志勇; 张云升; 姜骞; 孙国文

    2012-01-01

    To explore the effect of the supplementary binders and fine aggregates on the hydration process, the early-age microstructure evolution process was in-situ continuously monitored by using a new electrodeless resistivity apparatus for various cement-based materials. The influence of the water-to-binder ratio, the silica fume replacement percentage, the slag replacement percentage, the fly ash replacement percentage, the volume percentage of fine aggregates and the grain size of fine aggregates on the electrical resistivity were systematically investigated. The experimental results show that according to the development curve of the electrical resistivity of the cement-based materials, the 3 000 min early-age hydration process of the cement-based materials can be clearly classified into four stages: the dissolution stage, the dormant stage, the acceleration stage, and the deceleration stage. The development rate in the electrical resistivity decreases with the increase in the water-to-binder ratio. The electrical resistivity of the mortar is greater than that of the cement paste at the same water-to-binder ratio. The change rate of the electrical resistivity in the late stage is reduced by the mineral admixtures, while the hydration acceleration stage is advanced by the addition of the silica fume. During the early-age hydration process, the silica fume has the highest activity followed by the slag, and the fly ash has the lowest activity. The larger the volume percentage and grain size of the fine aggregates, the higher the electrical resistivity of the mortar.%为了考察辅助性胶凝材料和细骨料对水泥水化的影响,利用新型无电极电阻率仪原位连续监测水泥基材料早期的微结构演变进程,系统分析了水胶比、硅灰掺量、矿渣掺量、粉煤灰掺量、细骨料体积分数和骨料粒级对水泥基材料电阻率的影响.试验结果表明:在水化3 000 min内,根据水泥基材料电阻率的发展曲线,可将水

  8. 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.

  9. In vitro bioactivity of a tricalcium silicate cement

    International Nuclear Information System (INIS)

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

  10. Influence of pore structure on compressive strength of cement mortar.

    Science.gov (United States)

    Zhao, Haitao; Xiao, Qi; Huang, Donghui; Zhang, Shiping

    2014-01-01

    This paper describes an experimental investigation into the pore structure of cement mortar using mercury porosimeter. Ordinary Portland cement, manufactured sand, and natural sand were used. The porosity of the manufactured sand mortar is higher than that of natural sand at the same mix proportion; on the contrary, the probable pore size and threshold radius of manufactured sand mortar are finer. Besides, the probable pore size and threshold radius increased with increasing water to cement ratio and sand to cement ratio. In addition, the existing models of pore size distribution of cement-based materials have been reviewed and compared with test results in this paper. Finally, the extended Bhattacharjee model was built to examine the relationship between compressive strength and pore structure. PMID:24757414

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

    Directory of Open Access Journals (Sweden)

    Haitao Zhao

    2014-01-01

    Full Text Available This paper describes an experimental investigation into the pore structure of cement mortar using mercury porosimeter. Ordinary Portland cement, manufactured sand, and natural sand were used. The porosity of the manufactured sand mortar is higher than that of natural sand at the same mix proportion; on the contrary, the probable pore size and threshold radius of manufactured sand mortar are finer. Besides, the probable pore size and threshold radius increased with increasing water to cement ratio and sand to cement ratio. In addition, the existing models of pore size distribution of cement-based materials have been reviewed and compared with test results in this paper. Finally, the extended Bhattacharjee model was built to examine the relationship between compressive strength and pore structure.

  12. Design of Fit-for-Purpose Cement to Restore Cement-Caprock Seal Integrity

    Science.gov (United States)

    Provost, R.

    2015-12-01

    This project aims to study critical research needs in the area of rock-cement interfaces, with a special focus on crosscutting applications in the Wellbore Integrity Pillar of the SubTER initiative. This study will focus on design and test fit-for-purpose cement formulations. The goals of this project are as follows: 1) perform preliminary study of dispersing nanomaterial admixtures in Ordinary Portland Cement (OPC) mixes, 2) characterize the cement-rock interface, and 3) identify potential high-performance cement additives that can improve sorption behavior, chemical durability, bond strength, and interfacial fracture toughness, as appropriate to specific subsurface operational needs. The work presented here focuses on a study of cement-shale interfaces to better understand failure mechanisms, with particular attention to measuring bond strength at the cement-shale interface. Both experimental testing and computational modeling were conducted to determine the mechanical behavior at the interface representing the interaction of cement and shale of a typical wellbore environment. Cohesive zone elements are used in the finite element method to computationally simulate the interface of the cement and rock materials with varying properties. Understanding the bond strength and mechanical performance of the cement-formation interface is critical to wellbore applications such as sequestration, oil and gas production and exploration and nuclear waste disposal. Improved shear bond strength is an indication of the capability of the interface to ensure zonal isolation and prevent zonal communication, two crucial goals in preserving wellbore integrity. Understanding shear bond strength development and interface mechanics will provide an idea as to how the cement-formation interface can be altered under environmental changes (temperature, pressure, chemical degradation, etc.) so that the previously described objectives can be achieved. Sandia National Laboratories is a multi

  13. ULTRA-LIGHTWEIGHT CEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fred Sabins

    2001-10-23

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). Work reported herein addresses tasks performed in the fourth quarter as well as the other three quarters of the past year. The subjects that were covered in previous reports and that are also discussed in this report include: Analysis of field laboratory data of active cement applications from three oil-well service companies; Preliminary findings from a literature review focusing on problems associated with ultra-lightweight cements; Summary of pertinent information from Russian ultra-lightweight cement literature review; and Comparison of compressive strengths of ULHS systems using ultrasonic and crush methods Results reported from the fourth quarter include laboratory testing of ULHS systems along with other lightweight cement systems--foamed and sodium silicate slurries. These comparison studies were completed for two different densities (10.0 and 11.5 lb/gal) and three different field application scenarios. Additional testing included the mechanical properties of ULHS systems and other lightweight systems. Studies were also performed to examine the effect that circulation by centrifugal pump during mixing has on breakage of ULHS.

  14. Glass powder blended cement hydration modelling

    Science.gov (United States)

    Saeed, Huda

    The use of waste materials in construction is among the most attractive options to consume these materials without affecting the environment. Glass is among these types of potential waste materials. In this research, waste glass in powder form, i.e. glass powder (GP) is examined for potential use in enhancing the characteristics of concrete on the basis that it is a pozzolanic material. The experimental and the theoretical components of the work are carried out primarily to prove that glass powder belongs to the "family" of the pozzolanic materials. The chemical and physical properties of the hydrated activated glass powder and the hydrated glass powder cement on the microstructure level have been studied experimentally and theoretically. The work presented in this thesis consists of two main phases. The first phase contains experimental investigations of the reaction of glass powder with calcium hydroxide (CH) and water. In addition, it includes experiments that are aimed at determining the consumption of water and CH with time. The reactivity, degree of hydration, and nature of the pore solution of the glass powder-blended cement pastes and the effect of adding different ratios of glass powder on cement hydration is also investigated. The experiments proved that glass powder has a pozzolanic effect on cement hydration; hence it enhances the chemical and physical properties of cement paste. Based on the experimental test results, it is recommended to use a glass powder-to-cement ratio (GP/C) of 10% as an optimum ratio to achieve the best hydration and best properties of the paste. Two different chemical formulas for the produced GP C-S-H gel due to the pure GP and GP-CH pozzolanic reaction hydration are proposed. For the pure GP hydration, the produced GP C-S-H gel has a calcium-to-silica ratio (C/S) of 0.164, water-to-silica ratio (H/S) of 1.3 and sodium/silica ratio (N/S) of 0.18. However, for the GP-CH hydration, the produced GP C-S-H gel has a C/S ratio of 1

  15. 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.

  16. 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.

  17. 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.

  18. Macrodefect-free cements: chemistry and impact of the environment

    Energy Technology Data Exchange (ETDEWEB)

    Drabik, M.; Galikova, L.; Mojumdar, S.C. [Slovak Academy of Sciences, Bratislava (Slovakia). Inst. of Inorganic Chemistry

    2002-07-01

    To control and improve the moisture resistance is a long felt necessity of the MDF cements, chemical approaches together with material science contribute to the progress. Present results support our previous hypothesis about the impregnation or barier effect of poly-P on the MDF cements and enlarge the validity of this hypothesis to the blends of SAFB clinker, Portland cement and HPMC or poly-P. Compactness of Al(Fe)-O-P cross-links increases the intrinsic density and, consequently, impregnates the system against the uptake of moisture. In a sense of the theory of functional polymers, the intensity of grafting of polymer chains to the surface of grains increases if poly-P is used and with the prolonged processing. The scope of moisture attack on MDF cements synthesized from the blends of SAFB clinker, Portland cement and HPMC or poly-P, as quantified using mass changes as measure of moisture resistance, is strongly affected by the nature of polymer. The addition of Portland cement in the raw mix improves the moisture resistance of MDF cements. Thermal analysis shows: (i) the irreversible mass gain of 3 - 10% is arisen from carbonation and secondary hydration of cement grains and (ii) the Al(Fe)-O-C(P) cross-links remain intact in the moist environment at either ambient or extreme levels of humidity. (orig.)

  19. Ageing of Dry Cement Mixes for Finishing Purposes

    Directory of Open Access Journals (Sweden)

    Bronius VEKTARIS

    2013-09-01

    Full Text Available Dry building mixes, stored in the air, absorb water vapor and CO2 gas and ageing because properties of binding materials, mostly Portland cement, deteriorate after its prehydration and carbonation. In this paper the ageing singularities of dry cement mixes for finishing purposes and additives for retarding this process has been determinated. Ordinary and quickly hardening Portland cements absorb H2O and CO2 more than white cement – about 70 % – 75 % and 30 % – 38 % per month of innitial mass, respectively. White cement is more resistant to prehydration and carbonation, because it contains less C3A, C4AF and alkali, characterized initial activity. Dry mixes with white cement, although slower, but still worse after stored. Influence of routine dry mortar mixes ingredients and additives (methyl cellulose, pigments, sand and lime on prehydration properties of the mixes for finishing purpose is not substantial. Significant positive influence comes from the addition of fatty acid salts (zinc stearate or sodium oleate. The dry cement mixes for finishing purpose has been recomended to hydrophobisate with one of these additives, adding about 1 % by weight of cement during preducing mixes. DOI: http://dx.doi.org/10.5755/j01.ms.19.3.5243

  20. Solubility of Three Luting Cements in Dynamic Artificial Saliva

    Directory of Open Access Journals (Sweden)

    S. Nikzad

    2008-09-01

    Full Text Available Objective: The purpose of this study was to evaluate the solubility of three luting cements in artificial saliva.Materials and Methods: Twenty disks (10×4 mm of polycarboxylate, zinc phosphate and glass ionomer cements were prepared according to manufactures’ instructions. After setting, they were desiccated and each ten specimens were immersed in artificial saliva with special pH (3 or 5, circulated with magnetic field for 10 days. Then disks were again desiccated and weighed. Solubility values were deduced from these different measures.Results: For the two pH, solubility were significantly lower in glass ionomer luting ce-ment, and polycarboxylate showed the most weight loss of all the materials tested (P<0.05. The solubility values were more in acidic environment (P<0.05.Conclusion: The pH of the environment strongly affected the solubility of the materials. Cement type also has significant effects on solubility values.

  1. Rice husk derived waste materials as partial cement replacement in lightweight concrete Utilização de resíduos derivados da casca de arroz como substitutos parciais do cimento no concreto leve

    Directory of Open Access Journals (Sweden)

    Celso Yoji Kawabata

    2012-10-01

    Full Text Available In this study rice husk ash (RHA and broiler bed ash from rice husk (BBA, two agricultural waste materials, have been assessed for use as partial cement replacement materials for application in lightweight concrete. Physical and chemical characteristics of RHA and BBA were first analyzed. Three similar types of lightweight concrete were produced, a control type in which the binder was just CEMI cement (CTL and two other types with 10% cement replacement with, respectively, RHA and BBA. All types of similar lightweight concrete were prepared to present the same workability by adjusting the amount of superplasticizer. Properties of concrete investigated were compressive and flexural strength at different ages, absorption by capillarity, resistivity and resistance to chloride ion penetration (CTH method and accelerated carbonation. Test results obtained for 10% cement replacement level in lightweight concrete indicate that although the addition of BBA conducted to lower performance in terms of the degradation indicative tests, RHA led to the enhancement of mechanical properties, especially early strength and also fast ageing related results, further contributing to sustainable construction with energy saver lightweight concrete.Neste trabalho, cinzas de casca de arroz (RHA e cinzas de cama de frango (BBA, dois resíduos agrícolas, foram avaliadas para uso como substitutos parciais do cimento para produção de concreto leve. Características físicas e químicas de RHA e BBA foram analisadas. Três tipos semelhantes de concreto leve foram produzidos, um controle em que o ligante era totalmente cimento CEM I (CTL e dois outros tipos de concreto, com substituição de 10% com RHA e BBA, respectivamente. Todos os tipos de concreto leve foram feitos através do ajuste da quantidade de superplastificante para apresentarem a mesma trabalhabilidade. Propriedades de concreto investigados foram resistência à compressão e à flexão em diferentes idades

  2. The Influence of Abutment Surface Treatment and the Type of Luting Cement on Shear Bond Strength between Titanium/Cement/Zirconia

    Directory of Open Access Journals (Sweden)

    Beata Śmielak

    2015-01-01

    Full Text Available Objectives. The objectives of this study were to evaluate the shear bond strength of zirconia cylinders on a modified titanium surface using different luting cement types. Material and Methods. Eighty titanium disks were divided into two groups (n=40, which were treated with either grinding or a combination of sandblasting and grinding. Then, each group was subdivided into 4 groups (n=10 and the disks were bonded to disks of sintered zirconia using one of four cement types (permanent: composite cement; temporary: polycarboxylate cement, zinc-oxide-eugenol cement, and resin cement. Shear bond strength (SBS was measured in a universal testing machine. Fracture pattern and site characteristic were recorded. A fractographic analysis was performed with SEM. The chemical analysis of the composition of the fractures was performed using energy-dispersive X-ray spectroscopy (EDS. The results of the experiment were analyzed with two-way analysis of variance and Tukey post hoc test. Results. The highest mean values of SBS were achieved when grinding was combined with sandblasting and when composite cement was used (18.18 MPa. In the temporary cement group, the highest mean values of SBS were for polycarboxylate cement after grinding (3.57 MPa. Conclusion. The choice of cement has a crucial influence on the titanium-cement-zirconia interface quality.

  3. Material Properies of Intermediate Materials between Concrete and Gravelly Soil

    Science.gov (United States)

    Uchimura, Taro; Kuramochi, Yuko; Thai, Bach Thuan

    Compaction and strength properties of cement-mixed well-graded gravel are studied. Such materials can also be considered as a kind of concrete materials which has much lower cement contents than usual. New concepts on material properties related to their mixture ratio of cement, gravel (aggregate) and water, as well as their compaction density, are proposed, unifying the concepts of geotechnical engineering and concrete engineering. For materials with higher cement contents, the compaction curve becomes flat, with lower maximum compaction density, and higher optimum water contents. The triaxial compressive strength are clearly affected by the dry density, as well as the cement contents.

  4. Modelisation and numerical simulation for bulk crystal growth processes

    International Nuclear Information System (INIS)

    The aim of this work is to study the relevance of numerical simulation for improving the process control in the field of crystal growth. This investigation focused on the growth of semiconductor and halide crystals by the Bridgman solidification technique, the principle of which is to cool a seeded feed material contained in a crucible, either by pulling the crucible or by decreasing the temperature in the furnace. Calculations are performed with the finite element method, and for comparison, experiments are carried out on Bridgman pulling machines operating either in a laboratory or in industrial plants. Calculations and experimental data have shown a good agreement and a satisfactory reliability

  5. Reducing cement's CO2 footprint

    Science.gov (United States)

    van Oss, Hendrik G.

    2011-01-01

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

  6. Cement Mason's Curriculum. Instructional Units.

    Science.gov (United States)

    Hendirx, Laborn J.; Patton, Bob

    To assist cement mason instructors in providing comprehensive instruction to their students, this curriculum guide treats both the skills and information necessary for cement masons in commercial and industrial construction. Ten sections are included, as follow: related information, covering orientation, safety, the history of cement, and applying…

  7. Cement og politik

    DEFF Research Database (Denmark)

    Lund, Joachim

    2012-01-01

    as well as in the public sphere. Most of the extensive job creating measures he carried out as a minister for public works necessarily involved the use of great amounts of cement – the primary produce of F.L. Smidth & Co. Gunnar Larsen thus became an easy target for Communist propaganda, picturing him...... of the Soviet Union (including an F.L. Smidth & Co. cement plant in former Estonia). He spent the last 15 months of the occupation in Sweden and was arrested after having returned to Copenhagen in May, 1945. Although a Copenhagen city court prison sentence for economic collaboration was reversed, he had...

  8. Technology Roadmaps: Cement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    To support its roadmap work focusing on key technologies for emissions reductions, the International Energy Agency (IEA) also investigated one particular industry: cement. Cement production includes technologies that are both specific to this industry and those that are shared with other industries (e.g., grinding, fuel preparation, combustion, crushing, transport). An industry specific roadmap provides an effective mechanism to bring together several technology options. It outlines the potential for technological advancement for emissions reductions in one industry, as well as potential cross-industry collaboration.

  9. 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.

  10. A CONSTITUTIVE LAW OF CEMENT-BASED MATERIAL AT LARGE RANGE OF CONFINING PRESSURE STATE%水泥基材料在宽围压范围的本构模型

    Institute of Scientific and Technical Information of China (English)

    张研; 邵建富

    2011-01-01

    The triaxial compression test and hydrostatic compression test have been performed at first.Based on the experimental data, different mechanism of cement paste has been analyzed. According to thermodynamics theory, a new constitutive law is established and the damage criterion, two plastic mechanisms have been taken into account. This modelling considers also the influence of confining pressure. Numerical simulation shows that this constitutive law for cement-based materials can well explicit the main mechanical behavior at a large range of confining pressure state.%论文首先进行了水泥石的三轴试验和静水试验,根据试验结果分析了宽围压范围下不同力学机理对水泥石宏观力学性能的影响.提出了基于热力学定律的剪切塑性、孔隙塑性与破坏准则相互作用的弹塑性损伤本构模型.该模型有效的考虑了围压对材料主要力学特征的影响,提出了与损伤准则相关联的塑性硬化函数.数值解答与试验结果比较表明,该本构模型可以很好地描述水泥石在低围压状态下的脆性、中围压下的脆-塑性转换以及高围压下的孔隙塑性为主的力学特征.

  11. 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.

  12. Modelisation of Nitrification under Inhibited Environment by Moving Bed Bio-Film Reactor Technique

    Directory of Open Access Journals (Sweden)

    Pham T.H. Duc

    2010-01-01

    Full Text Available Problem statement: Nitrification by Moving Bed Biofilm Reactor (MBBR involves physical, chemical and biological processes to remove toxic ammonia for aquaculture that are governed by a variety of parameters, like substrate and dissolved oxygen concentrations, organic matters, temperature, pH, alkalinity and turbulence level, which impact negatively or positively on nitrification kinetics. Approach: The situation becomes more serious as the reaction rate is inhibited by low ammonium concentration and high salinity. That problems usually occur in treatment systems of aquatic breeding hatcheries. Results: In this study, experiments have been conducted to evaluate the impact of salinity on nitrification rate through kinetic constant (k and reaction order (n based on general equation v = kCn. Moving bed biofilm reactor was operated continuously at same initial amounts of nitrogen and Phosphorus very low (oligotrophic conditions. Firstly, over view the impact of salinity on kinetic rate to modeling that effect k and n to modelisation that affects and obtained the impact of salinity content in the reaction medium (X and the acclimatization phase (Y on the kinetic constant (k = 0.097 e (-0.0003Yƒ{0.0346X and on the kinetic order (n = (0.0002Y-0.0195 X-0.009Y + 1.2382. Conclusion/Recommendations: Results from kinetic analysis allowed the prediction of the reaction rate and reaction yield with rather high accuracy, helping the design and operation of a biofilter under practical conditions.

  13. MTF performance: measurements, modelisation, and optimization for Sofradir II-VI IR photodetectors

    Science.gov (United States)

    Berthoz, Jocelyn; Rubaldo, Laurent; Maillard, Magalie; Taalat, Rachid; Grille, Romain; Péré-Laperne, Nicolas; Kerlain, Alexandre; Ferron, Alexandre; Gravrand, Olivier

    2015-01-01

    SOFRADIR is widely present on the IR detector market for high-performance space, military and security applications thanks to a well mastered Mercury Cadmium Telluride (MCT) technology, and to the recent acquisition of the III-V InSb, InGaAs, and QWIP technologies. As a result, strong and continuous development efforts are deployed to deliver cutting edge products with improved performances in terms of sensitivity, spatial and thermal resolution. The actual trend in quantum IR detector development is the design of very small pixel, with high operating temperature. The selfconfinement of neighboring diodes may not be efficient enough to maintain optimal modulation transfert function (MTF). This paper presents the recent developments achieved in Sofradir in terms of MTF measurements protocol challenged by the pitch reduction. An overview of state of the art MTF results with optimized measurement technic will be shown, from SWIR to VLWIR MCT focal plane. In order to optimize device performances and reduce development cycle time, this experimental approach has been coupled with finite elements modelisation (FEM). Optimized MTF results for 10μm pitch and HOT MCT technology will be exposed.

  14. Biological Rhythms Modelisation of Vigilance and Sleep in Microgravity State with COSINOR and Volterra's Kernels Methods

    Science.gov (United States)

    Gaudeua de Gerlicz, C.; Golding, J. G.; Bobola, Ph.; Moutarde, C.; Naji, S.

    2008-06-01

    The spaceflight under microgravity cause basically biological and physiological imbalance in human being. Lot of study has been yet release on this topic especially about sleep disturbances and on the circadian rhythms (alternation vigilance-sleep, body, temperature...). Factors like space motion sickness, noise, or excitement can cause severe sleep disturbances. For a stay of longer than four months in space, gradual increases in the planned duration of sleep were reported. [1] The average sleep in orbit was more than 1.5 hours shorter than the during control periods on earth, where sleep averaged 7.9 hours. [2] Alertness and calmness were unregistered yield clear circadian pattern of 24h but with a phase delay of 4h.The calmness showed a biphasic component (12h) mean sleep duration was 6.4 structured by 3-5 non REM/REM cycles. Modelisations of neurophysiologic mechanisms of stress and interactions between various physiological and psychological variables of rhythms have can be yet release with the COSINOR method. [3

  15. The mechanical effect of the existing cement mantle on the in-cement femoral revision.

    LENUS (Irish Health Repository)

    Keeling, Parnell

    2012-08-01

    Cement-in-cement revision hip arthroplasty is an increasingly popular technique to replace a loose femoral stem which retains much of the original cement mantle. However, some concern exists regarding the retention of the existing fatigued and aged cement in such cement-in-cement revisions. This study investigates whether leaving an existing fatigued and aged cement mantle degrades the mechanical performance of a cement-in-cement revision construct.

  16. CEMENT BONDED COMPOSITES – A MECHANICAL REVIEW

    Directory of Open Access Journals (Sweden)

    Stephan Frybort

    2008-05-01

    Full Text Available Over the last years promising cement bonded wood composites for structural purposes have evolved. Durability, toughness, high dimen-sional stability, resistance against environmental influences such as biodegradation or weathering but also availability of the raw material as well as economic factors are features which can make cement-bonded composites superior to conventionally bonded composites. This paper reviews the relationship of diverse parameters, including density and particle size on mechanical and physical properties of cement bonded composites, based on published sources from the last 60 years. For general and recent information about bonding mechanisms, compatibility and setting problems, determination and improvement of compatibility, the used raw materials as well as accelerators are discussed. The main part deals with failure mechanisms in connection with several production parameters. Furthermore, the influence of particle size and geometry, orientation of the particles, cement-wood ratio and the effect of accelerators and treatment of the particles on modulus of elasticity, modulus of rupture as well as thickness swelling are discussed.

  17. Kinetics of strength gain of biocidal cements

    Directory of Open Access Journals (Sweden)

    Rodin Aleksandr Ivanovich

    Full Text Available Biocorrosion becomes the determinative durability factor of buildings and constructions. Damages of construction materials caused by bacteria, filamentous fungi, actinomycetes constitute a serious danger to the constructions of a building or a structure and to the health of people. Biodeteriorations are typical both in old and new constructions. A great quantity of destruction factors of industrial and residential buildings under the influence of microorganisms was established in practice. Providing products and constructions based on concretes fungicidal and bactericidal properties is an important direction of modern construction material science. The most efficient way to solve this task is creation of biocidal cements. The article presents the results of experimental studies of kinetic dependences of strength gain by biocidal cements by physico-mechanical and physico-chemical analysis methods. The identical velocity character of initial hydration of the developed compositions of biocidal cements is set, as well as a more calm behavior of hardening processes at later terms. It has been established that the compositions of biocidal cements modified by sodium sulfate and sodium fluoride possess the greatest strength.

  18. Modeling temperature and moisture fields in conditioned spaces using zonal approach, including sorption phenomena in buildings materials; Modelisation thermo-hydro-aeraulique des locaux climatises selon l'approche zonale (prise en compte des phenomenes de sorption d'humidite)

    Energy Technology Data Exchange (ETDEWEB)

    Cordeiro Mendoca, K.

    2004-05-15

    Building simulation models represent in our days an important tool for building conception and performance analysis. Although moisture interacts in many ways with the whole building affecting therefore its behavior, frequently these models neglects the interactions between them. In addition, in most of them, indoor air conditions are considered uniform, which is a non-realistic assumption in conditioned spaces. In this work, a model to predict temperature and moisture fields in conditioned spaces, using zonal approach, is proposed. This method is based in dividing spatially a room in a relative small number of zones, typically on the order of tens to hundreds, where the state variables of air are considered uniform, with the exception of pressure that varies hydrostatically. While not as fine-grained as CFD simulation, zonal models do give useful information about temperature and moisture distributions that is important in comfort analysis. The proposed model was structured in three groups of sub-models representing the three building domains: indoor air, envelope and HVAC system. The indoor air sub-model is related to the indoor air space, where airflow speed can be considered weak. The envelope sub-model is related to the radiation exchanges between envelope and its neighborhood, and to the simultaneous heat and mass transfers across the envelope material. This latest can be represented by four sub-models of different complexity levels, with two of them taking into account moisture adsorption and desorption by building materials. Concerning to the HVAC system model, it refers to the whole system that means equipment, control and specific airflow from equipment. All sub-models were coupled into a modular simulation environment, SPARK, well-adapted to compare different models. The applicability of the proposed model is shown by two examples. The first one shows the importance of considering moisture sorption phenomena in the prediction of indoor air conditions

  19. Sulfate resistance evaluation of the cement with fly ash (using the Koch & Steinegger method)

    OpenAIRE

    Irassar, Edgardo F.; Jorge D Sota; Batic, Oscar R.

    1988-01-01

    The increase of active mineral admixtures consumption in contemporaneous cementiceous materials has stablished revision of some test methods. In the evaluation of blended cement durability, many accelerated tests of large application in portland cements become unvalid, because they don't allow to value the improvements produced by pozzolan materials. Koch-Steinegger Method appears as the most appropiate to evaluate sulfate resistance of cement with active mineral admixtures. ...

  20. Heterogeneous nucleation of ice from supercooled NaCl solution confined in porous cement paste

    OpenAIRE

    Zeng, Qiang; Li, Kefei; FEN CHONG, Teddy

    2015-01-01

    Clarifying the nucleation process of chloride-based deicing salt solution (e.g., NaCl solution) confined in cement-based porous materials remains an important issue to understand its detrimental effects on material substrates. In this study, the pore structures of hardened cement pastes were characterized by mercury-intrusion and nitrogen-sorption porosimetry. The ice nucleation temperature of NaCl solution of different concentrations confined in the hardened cement pastes was measured and an...

  1. 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.

  2. Cements with low Clinker Content

    Science.gov (United States)

    García-Lodeiro, I.; Fernández-Jiménez, A.; Palomo, A.

    2015-11-01

    Hybrid alkaline cements are multi-component systems containing a high percentage of mineral additions (fly ash, blast furnace slag), low proportions (alkaline activators. The substantially lower amount of clinker needed to manufacture these binders in comparison to ordinary Portland cement is both economically and ecologically beneficial. Their enormous versatility in terms of the raw materials used has made them the object of considerable interest. The present study explored the mechanical strength of binary blends mixes; B1= 20% clinker (CK) + 80% fly ash (FA) and B2=20% clinker + 80% blast furnace slag (BFS), both hydrated in the presence and absence of an alkaline activator specifically designed for this purpose. The use of the activator enhanced the development of early age strength considerably. All the hydrated matrices were characterised with XRD, SEM/EDX and (29Si and 27Al) NMR. The use of the alkaline activator generated reaction products consisting primarily of a mix of gels ((N,C)-A-S-H and C-A-S-H) whose respective proportions were found to depend upon system composition and initial reactivity.

  3. Methodological developments and qualification of calculation schemes for the modelling of photonic heating in the experimental devices of the future Jules Horowitz material testing reactor (RJH); Developpements methodologiques et qualification de schemas de calcul pour la modelisation des echauffements photoniques dans les dispositifs experimentaux du futur reacteur d'irradiation technologiques Jules Horowitz (RJH)

    Energy Technology Data Exchange (ETDEWEB)

    Blanchet, D

    2006-07-01

    The objective of this work is to develop the modelling of the nuclear heating of the experimental devices of the future Jules Horowitz material testing reactor (RJH). The strong specific nuclear power produced (460 kW/l), induces so intense photonic fluxes which cause heating and large temperature gradients that it is necessary to control it by an adequate design. However, calculations of heating are penalized by the very large uncertainties estimated at a value of about 30% (2*{sigma}) coming from the gaps and uncertainties of the data of gamma emission present in the libraries of basic nuclear data. The experimental program ADAPh aims at reducing these uncertainties. Measurements by thermoluminescent detectors (TLD) and ionisation chambers are carried out in the critical assemblies EOLE (Mox) and Minerve (UO{sub 2}). The rigorous interpretation of these measurements requires specific developments based on Monte-Carlo simulations of coupled neutron-gamma and gamma-electron transport. The developments carried out are made different in particular by the modelling of cavities phenomena and delayed gamma emissions by the decay of fission products. The comparisons calculation-measurement made it possible to identify a systematic bias confirming a tendency of calculations to underestimate measurements. A Bayesian method of adjustment was developed in order to re-estimate the principal components of the gamma heating and to transpose the results obtained to the devices of the RJH, under conditions clearly and definitely representative. This work made possible to reduce significantly the uncertainties on the determination of the gamma heating from 30 to 15 per cent. (author)

  4. Produktie van cement

    NARCIS (Netherlands)

    Smit JRK; Coenen PWHG; Matthijsen AJCM; LAE; TAUW

    1995-01-01

    This document on cement production has been published within the SPIN project. In this project information has been collected on industrial plants or industrial processes to afford support to governmental policy on emission reduction. This document contains information on the processes, emission sou

  5. Osteotransductive bone cements.

    Science.gov (United States)

    Driessens, F C; Planell, J A; Boltong, M G; Khairoun, I; Ginebra, M P

    1998-01-01

    Calcium phosphate bone cements (CPBCs) are osteotransductive, i.e. after implantation in bone they are transformed into new bone tissue. Furthermore, due to the fact that they are mouldable, their osteointegration is immediate. Their chemistry has been established previously. Some CPBCs contain amorphous calcium phosphate (ACP) and set by a sol-gel transition. The others are crystalline and can give as the reaction product dicalcium phosphate dihydrate (DCPD), calcium-deficient hydroxyapatite (CDHA), carbonated apatite (CA) or hydroxyapatite (HA). Mixed-type gypsum-DCPD cements are also described. In vivo rates of osteotransduction vary as follows: gypsum-DCPD > DCPD > CDHA approximately CA > HA. The osteotransduction of CDHA-type cements may be increased by adding dicalcium phosphate anhydrous (DCP) and/or CaCO3 to the cement powder. CPBCs can be used for healing of bone defects, bone augmentation and bone reconstruction. Incorporation of drugs like antibiotics and bone morphogenetic protein is envisaged. Load-bearing applications are allowed for CHDA-type, CA-type and HA-type CPBCs as they have a higher compressive strength than human trabecular bone (10 MPa).

  6. 基于中子成像的水泥基材料毛细吸水动力学研究%Water capillary suction dynamics of cement-based materials based on neutron radiography method

    Institute of Scientific and Technical Information of China (English)

    张鹏; 赵铁军; Wittmann F.H.; Lehmann E.

    2011-01-01

    总结了国内外有关水泥基材料毛细吸水的动力学机理及其现有模型,应用中子成像技术对其毛细吸水过程进行了可视化再现,对水分侵入的空间分布规律进行了定量分析.结果表明,在毛细孔吸附力作用下,水分前锋不断向水泥基材料内部推进,在吸水初期速度较快,后趋于平缓直至稳定;水分侵入曲线在深度和含量上同时增长,可以由线性+反S形模型来描述其空间分布特点,并与实测结果吻合良好;现有的"时间开方"及其修正模型对毛细吸水的后期预测不太合理,本文提出的渗透系数双曲线衰减模型更符合真实结果.%Dynamic mechanism and current models for water capillary suction of cement-based materials are summarized. Neutron Radiography method was applied to visualize the time dependent process of capillary suction and quantitatively to analyze the spatial moisture distribution in the material during water capillary suction. Results indicate that water front moved deeper into the cement-based materials with higher speed at the beginning of contact followed by lower penetration speed until nearly equilibrium. Both in the direction of depth and quantity the moisture distribution curve increased, which variation can be described by linear-plus-reverse-sigmoid model. For the relationship between water penetration depth and contact time, current square-root-of-time model and its modified models are not perfect to predict capillary suction at the late age. A hyperbolic regression model for coefficient of water penetration is developed which is well accord with the observed data.

  7. 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.

  8. Energy optimization and reduction of carbon footprint in cement manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Gallestey, Eduardo; Crosley, Gabriela; Wilson, Andrew; Maier, Urs; Hoppler, Rolf; Boerrnert, Thomas

    2010-09-15

    Cement producers are large consumers of thermal and electrical energy, which are only available at steadily increasing costs. Efforts to reduce demands by using higher efficiency equipment and substituting -fuels and raw materials to lower production costs have been addressed in recent years. Under the Kyoto Protocol industrialised countries agreed to reduce their collective greenhouse gas emissions. Cement producers as some of the largest emitters of CO2 have been especially challenged to find new and innovative ways to reduce greenhouse gas emissions. This paper summarise some ABB technologies developed to assist the cement industry to meet these goals.

  9. Industrial trial to produce a low clinker, low carbon cement

    OpenAIRE

    Vizcaíno-Andrés, L. M.; Sánchez-Berriel, S.; Damas-Carrera, S.; A. Pérez-Hernández; Scrivener, K. L.; Martirena-Hernández, J. F.

    2015-01-01

    A preliminary assessment of conditions for the industrial manufacture of a new cementitious system based on clinker-calcined clay and limestone, developed by the authors, referred as “low carbon cement” is presented. The new cement enables the substitution of more than 50% of the mass of clinker without compromising performance. The paper presents the follow-up of an industrial trial carried out in Cuba to produce 130 tonnes of the new cement at a cement plant. The new material proved to fulf...

  10. Porous surface modified bioactive bone cement for enhanced bone bonding.

    Directory of Open Access Journals (Sweden)

    Qiang He

    Full Text Available BACKGROUND: Polymethylmethacrylate bone cement cannot provide an adhesive chemical bonding to form a stable cement-bone interface. Bioactive bone cements show bone bonding ability, but their clinical application is limited because bone resorption is observed after implantation. Porous polymethylmethacrylate can be achieved with the addition of carboxymethylcellulose, alginate and gelatin microparticles to promote bone ingrowth, but the mechanical properties are too low to be used in orthopedic applications. Bone ingrowth into cement could decrease the possibility of bone resorption and promote the formation of a stable interface. However, scarce literature is reported on bioactive bone cements that allow bone ingrowth. In this paper, we reported a porous surface modified bioactive bone cement with desired mechanical properties, which could allow for bone ingrowth. MATERIALS AND METHODS: The porous surface modified bioactive bone cement was evaluated to determine its handling characteristics, mechanical properties and behavior in a simulated body fluid. The in vitro cellular responses of the samples were also investigated in terms of cell attachment, proliferation, and osteoblastic differentiation. Furthermore, bone ingrowth was examined in a rabbit femoral condyle defect model by using micro-CT imaging and histological analysis. The strength of the implant-bone interface was also investigated by push-out tests. RESULTS: The modified bone cement with a low content of bioactive fillers resulted in proper handling characteristics and adequate mechanical properties, but slightly affected its bioactivity. Moreover, the degree of attachment, proliferation and osteogenic differentiation of preosteoblast cells was also increased. The results of the push-out test revealed that higher interfacial bonding strength was achieved with the modified bone cement because of the formation of the apatite layer and the osseointegration after implantation in the bony

  11. Advanced cement solidification technique for spent resins

    International Nuclear Information System (INIS)

    In the past 40 years, the nuclear facilities of China Institute of Atomic Energy (CIAE) produced an amount of radioactive organic resins, a kind of problematic stream in nuclear industry. As these facilities were stepping into decommissioning, the treatment of the spent organic resins was put on the agenda. The various routes for spent resin treatment such as incineration, advanced oxidation, cement immobilization, etc, were considered. Each method has its advantages and disadvantages when applied in the treatment of spent resins. Since the quantities of the spent organic resins were relatively small and an experience with variety of cementation processes existed in CIAE, predominately for immobilization of the evaporated concentrates, the option of direct encapsulation of the spent organic resins into cementitious materials was adopted in 2003, as a preferred method from the point of view of saving the on the cost of the disposal. In order to realize the end goal, the main work consisted of: the survey of the source terms; cementitious material formula investigation; and the process development. This work, which was undertaken in the following years, is addressed as follows. Source terms of the spent resins in CIAE were to be made clear firstly. The results showed that a total of 24-29 m3 of spent resins was generated and accumulated in the past 40 years. Spent resin arose from two research reactors (heavy water reactor and light water reactor), and from the waste management plant. The amount of the spent resins from the heavy water reactor was 1m3 or so, but its radioactive concentration was high to ∼108-∼109Bq/m3. Two kinds of cements, ASC and OPC cement were selected next, as the solidifying matrix to be investigated. A mixture surface response approach was employed to design experiment and interpret data. In comparison, ASC was superior to OPC cement and it displayed preferable performances to encapsulate spent resins. The optimum formulation is:1) resin

  12. Monitoring of sulphate attack on hardened cement paste studied by synchrotron XRD

    Science.gov (United States)

    Stroh, J.; Meng, B.; Emmerling, F.

    2015-10-01

    The complex matter of external sulphate attack on cement-based construction materials is still not completely understood. The concentration of sulphate is a crucial factor for the formation of secondary phases and phase transitions of cement hydrates due to sulphate ingress into the microstructure. The sulphate attack on building materials for high and low sulphate concentrations was monitored by laboratory experiments. Hardened cement paste consisting of ordinary Portland cement (CEM I) were exposed to aqueous solutions of sodium sulphate for 18 months. Three sample compositions were used for this research, including different supplementary cementitious materials (SCM). The phase composition was determined for different time spans by high resolution synchrotron X-ray diffraction. Cross sections of exposed cement prisms were investigated as a representation of the microstructural profile. Based on the data, a temporal and spatial determination of the stages of the sulphate attack and the deterioration course was possible. Cement matrices blended with slag showed the highest resistance against sulphate attack.

  13. The crucial effect of early-stage gelation on the mechanical properties of cement hydrates

    Science.gov (United States)

    Ioannidou, Katerina; Kanduč, Matej; Li, Lunna; Frenkel, Daan; Dobnikar, Jure; Del Gado, Emanuela

    2016-07-01

    Gelation and densification of calcium-silicate-hydrate take place during cement hydration. Both processes are crucial for the development of cement strength, and for the long-term evolution of concrete structures. However, the physicochemical environment evolves during cement formation, making it difficult to disentangle what factors are crucial for the mechanical properties. Here we use Monte Carlo and Molecular Dynamics simulations to study a coarse-grained model of cement formation, and investigate the equilibrium and arrested states. We can correlate the various structures with the time evolution of the interactions between the nano-hydrates during the preparation of cement. The novel emerging picture is that the changes of the physicochemical environment, which dictate the evolution of the effective interactions, specifically favour the early gel formation and its continuous densification. Our observations help us understand how cement attains its unique strength and may help in the rational design of the properties of cement and related materials.

  14. Bone cements for percutaneous vertebroplasty and balloon kyphoplasty: Current status and future developments

    Directory of Open Access Journals (Sweden)

    Zhiwei He

    2015-01-01

    Full Text Available Osteoporotic vertebral compression fractures (OVCFs have gradually evolved into a serious health care problem globally. In order to reduce the morbidity of OVCF patients and improve their life quality, two minimally invasive surgery procedures, vertebroplasty (VP and balloon kyphoplasty (BKP, have been developed. Both VP and BKP require the injection of bone cement into the vertebrae of patients to stabilize fractured vertebra. As such, bone cement as the filling material plays an essential role in the effectiveness of these treatments. In this review article, we summarize the bone cements that are currently available in the market and those still under development. Two major categories of bone cements, nondegradable acrylic bone cements (ABCs and degradable calcium phosphate cements (CPCs, are introduced in detail. We also provide our perspectives on the future development of bone cements for VP and BKP.

  15. Exploitation and Application of a New Filling Cementing Materials with Full Tailings of Iron Mine%铁矿全尾砂新型充填胶凝材料的开发及应用研究

    Institute of Scientific and Technical Information of China (English)

    杨志强; 苏林; 高谦; 杨啸

    2015-01-01

    Mining with full tailing filling is the development tendency to exploit iron ore. Reducing the mining cost is the only way to keep iron ore filling stoping. With water-quenched slag as main raw material,alkali and salt as a composite activa-tor,a new type of full-tailing cementing material called as KWF (full tailings consolidated powder in mine) was obtained. Com-pared with the cement,the KWF has features of lower cost and higher strength. It has obvious advantage for the full tailing fill-ing with high clay. The KWF instead of cement to be used in filling mining can reduce the cost of filling mining,and also real-ize the comprehensive utilization of the solid waste,so as to protect the environment and realize no waste mining. The KWF has been produced by Tanglong New Building Material Co. ,Ltd. and applied in the iron mine in Dongkai mining company with sig-nificant economic and social benefits obtained. It lays a foundation for the filling stoping of large lean iron ore in Sijiaying dis-trict.%全尾砂充填法采矿是未来铁矿石开采的发展趋势,降低采矿成本是铁矿充填法采矿的必由之路。以水淬渣粉作为主要原料,采用碱和盐复合激发剂激发,获得了一种全尾砂新型充填胶凝材料—矿山尾砂固结粉(简称矿尾粉,代号为KWF)。与水泥材料相比,矿尾粉成本低、强度高,对含泥量高的全尾砂充填料优势更显著。采用矿尾粉替代水泥用于铁矿充填法采矿,不仅能够降低充填采矿成本,而且还能够实现固体废弃物资源化利用,从而保护环境和无废开采。矿尾粉新型充填胶凝材料已在唐龙新型建材有限公司工业化生产,在东凯矿业公司铁矿山应用,获得了显著的经济效益和社会效益;为在建设中的司家营地区大型贫铁矿充填法采矿奠定了基础。

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

    OpenAIRE

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

    2015-01-01

    Cement production contributes to extensive CO2 emissions. However, the climate impact can vary significantly between different production systems and different types of cement products. The market is dominated by ordinary Portland cement, which is based on primary raw materials and commonly associated with combustion of vast amounts of fossil fuels. Therefore, the production of Portland cement can be described as a rather linear process. But there are alternative options, for example, involvi...

  17. 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

  18. Preparation and characterization of nano-hydroxyapatite/carboxymethychitosan-sodium alginate bone cement composite material%纳米羟基磷灰石/羧甲基壳聚糖-海藻酸钠复合骨水泥的性能

    Institute of Scientific and Technical Information of China (English)

    肖海军; 薛锋; 何志敏; 金粉勤; 沈玉春

    2011-01-01

    BACKGROUND: Bone adhesives have more or few shortcomings themselves at present.OBJECTIVE: To develop a new kind of bioactive bone cement that can be used as fracture adhesion.METHODS: Nano-hydroxyapatite/carboxymethychitosan-sodium alginate bone cement composite material as solid phase wasprepared through a co-precipitation method, and citric acid derivant as liquid phase was prepared for solution. By optimizedexperimentation in situ setting, the appropriate prescription of the cement was screened out according to the test of setting time,compressive strength, tensile strength, anti -washout ability, and microstructure and crystal construction of the cement werecharacterized by using Fourier transform infrared spectroscopy and scanning electron microscope.RESULTS AND CONCLUSION: When the mass ratio of nano-hydroxyapatite/carboxymethychitosan-sodium alginate was 65/35(among carboxymethychitosan/sodium alginate 4∶1) and liquid/solid was 1.0∶ 0.5 (g: mL), the prepared cement was paste-likewith good plasti city and anti -washout ability; the setting time was 12 to 18 minutes; the compressive strength was (4.5±2.1) MPa;the tensile strength of the femoral head of pigs had no difference at 25 ℃ and 37 ℃ in vitro (P > 0.05); the tensile strength at2 hours was 94% similar as that at 24 hours after the setting; the range of the porous structure was 100-300 μm;Nano-hydroxyapatite was well-distributed in the porous structure. The nano-hydroxyapatite/carboxymethychitosan-sodiumalginate bone cement has good biological activity, appropriate compressive strength, and preferable adhesive strength.%背景:目前普遍使用的黏合剂对粉碎骨折块进行黏合复位或多或少都存在一些缺陷.目的:研制具有黏接骨骼作用的生物活性骨水泥.方法:应用共沉淀法制备纳米羟基磷灰石/羧甲基壳聚糖-海藻酸钠复合材料作为骨水泥的固相粉体,将柠檬酸衍生物配制成溶液作为液相.通过优化实验,从骨水泥

  19. Clay content of argillites: Influence on cement based mortars

    OpenAIRE

    Habert, Guillaume; CHOUPAY, Nathalie; Escadeillas, Gilles; MONTEL, Jean Marc; Guillaume, D

    2009-01-01

    The pozzolanic activity of four heated powders containing different clays has been tested. Mineral transformations during calcination from 20 to 900 °C have been followed by X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC). Compressive strength tests were performed at 1, 7 and 28 days on cement-clay mortars using 30% of pozzolanic material as a replacement by mass for cement. Calcination temperatures corresponded to the stages of potentially high reactivity identified by XR...

  20. Ternary blend cements concrete. Part II: Transport mechanism

    OpenAIRE

    Irassar, E. F.; Bonavetti, V. L.; Menéndez, G.

    2007-01-01

    With today’s extensive use of cements containing two or more additions (blended cements), predicting concrete durability on the grounds of its strength alone leads to errors that may affect the service life of the resulting structures. Indeed, concrete of a given strength class can be made from different materials and proportions of widely varying durability. The present study evaluated water absorption, sorptivity and initial surface absorption in concrete made with unadditi...