The Experts below are selected from a list of 216 Experts worldwide ranked by ideXlab platform
Cafer Celik - One of the best experts on this subject based on the ideXlab platform.
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determination of the optimum conditions for de icing salt scaling resistance of concrete by visual examination and surface scaling
Construction and Building Materials, 2010Co-Authors: Remzi şahin, Mehmet Ali Tasdemir, Cafer CelikAbstract:Abstract One of the main objectives of this work is to determine the most important parameter that affects the scaling resistance of concrete. Another objective is to investigate combined effects of finishing treatment and air-entrainment on the freeze–thaw scaling of horizontal concrete surfaces subjected to de-icing salt exposure. The parameters studied in this work were; water–cement ratio, cement content, curing condition, the air-Entraining Admixture, and second finishing treatment. The total number of freeze–thaw cycles was 50. In the experiments, both visual examination according to ASTM C 672 and scaling test methods were considered. The parameters studied were optimized using Taguchi Optimisation Method. It has been shown that the use of de-icing salt on concrete surface causes gradual deterioration from the surface into the inner section. There is a significant positive effect of air-entrainment on the freeze–thaw scaling at horizontal concrete surfaces. It can be concluded that the second finishing treatment has a positive effect on first cycles but loses its effect on the proceeding cycles.
Remzi şahin - One of the best experts on this subject based on the ideXlab platform.
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determination of the optimum conditions for de icing salt scaling resistance of concrete by visual examination and surface scaling
Construction and Building Materials, 2010Co-Authors: Remzi şahin, Mehmet Ali Tasdemir, Cafer CelikAbstract:Abstract One of the main objectives of this work is to determine the most important parameter that affects the scaling resistance of concrete. Another objective is to investigate combined effects of finishing treatment and air-entrainment on the freeze–thaw scaling of horizontal concrete surfaces subjected to de-icing salt exposure. The parameters studied in this work were; water–cement ratio, cement content, curing condition, the air-Entraining Admixture, and second finishing treatment. The total number of freeze–thaw cycles was 50. In the experiments, both visual examination according to ASTM C 672 and scaling test methods were considered. The parameters studied were optimized using Taguchi Optimisation Method. It has been shown that the use of de-icing salt on concrete surface causes gradual deterioration from the surface into the inner section. There is a significant positive effect of air-entrainment on the freeze–thaw scaling at horizontal concrete surfaces. It can be concluded that the second finishing treatment has a positive effect on first cycles but loses its effect on the proceeding cycles.
Robert B Lacount - One of the best experts on this subject based on the ideXlab platform.
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measurement of adsorption of air Entraining Admixture on fly ash in concrete and cement
Cement and Concrete Research, 2001Co-Authors: John P Baltrus, Robert B LacountAbstract:Abstract A method using UV–Vis spectrophotometry for measuring the adsorption of air-Entraining Admixture (AEA) on the components of cements was optimized. The method was then used to measure the adsorption of AEA on a series of Class F fly ash samples with carbon concentrations of up to 14.6%. Class F fly ash carbons were found to have a very low capacity for AEA compared to Portland cement. The adsorption capacities of the fly ashes were compared to their carbon concentrations and foam index values. A lack of correlation between adsorption capacity and foam index was primarily due to differences in equilibration times used for the two measurements. Ultimately the Foam Index Test was found to be unsatisfactory for measuring the adsorption of AEA by fly ash carbon. The UV–Vis method is not necessarily a better choice for measuring AEA adsorption by carbon because soluble Ca 2+ and Mg 2+ ions from the fly ash were found to interfere with the UV–Vis method due to the formation of precipitates.
Denis Beaupre - One of the best experts on this subject based on the ideXlab platform.
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Rheology and bonding characteristics of self-leveling concrete as a repair material
Materials and Structures, 1999Co-Authors: P. Lacombe, Denis Beaupre, N. PouliotAbstract:This paper presents the first part of a study under-taken to measure the potential of self-leveling concrete to perform overhead repairs. The performances of self-leveling concrete in terms of its filling ability and bonding characteristics was compared to dry-mixture shotcrete and to normal cast-in-place concrete. Self-leveling mixture characteristics included the presence of superplasticizer, viscosity-modifying Admixture (welan gum), air-Entraining Admixture (AEA) and silica fume.
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USE OF SET ACCELERATING AdmixtureS IN DRY-MIX SHOTCRETE
Journal of Materials in Civil Engineering, 1997Co-Authors: Marc Jolin, Denis Beaupre, Michel Pigeon, Ann LamontagneAbstract:Tests were carried out to study the influence of set accelerating Admixtures on the properties of dry-mix shotcrete, especially its durability. A total of 27 mixtures were shot, using two different types of cement (ASTM Type I with silica fume as partial cement replacement and ASTM Type III) and five different accelerators at various dosages. Half of these mixtures were shot with an air-Entraining Admixture. In addition to the determination of the setting time, the following properties were measured (on the hardened shotcrete): air void characteristics, compressive strength, drying shrinkage, rapid freezing and thawing resistance, and deicer salt scaling resistance. Results indicate that although all accelerators can reduce the initial and final setting times, some of them considerably decrease the durability, particularly the deicer salt scaling resistance. As a rule, better results were obtained with the mixtures containing the Type III cement than with those containing the Type I and silica fume. The tests confirm the importance of the use of an air-Entraining Admixture to obtain an adequate frost and deicer salt scaling resistance.
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Use of Air-Entraining Admixtures in Dry-Mix Shotcrete
Aci Materials Journal, 1996Co-Authors: Ann Lamontagne, Michel Pigeon, Richard Pleau, Denis BeaupreAbstract:Tests were performed to study the influence of the type of cement and the type and dosage of air-Entraining Admixtures on the properties of dry-mix shotcrete, particularly on resistance to salt scaling. A total of 21 mixes were made using three types of cement (normal portland cement, high-early-strength portland cement, and silica fume cement), three air-Entraining Admixtures (a synthetic detergent, a sulfonated salt of hydrocarbon, and a vinsol resin), and five dosages of air-Entraining Admixtures (0, 10, 20, 30, and 40 ml per liter of water). Test results reveal that the use of an air-Entraining Admixture can lead to a significant decrease in the spacing factor and a significant increase in scaling resistance. The results further show that the properties of air-entrained shotcretes made with normal portland cement and high-early-strength portland cement were similar, but that drying shrinkage and chloride ion permeability were lower in those containing silica fume.
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DEICER SALT SCALING RESISTANCE OF DRY- AND WET-PROCESS SHOTCRETE
Aci Materials Journal, 1994Co-Authors: Denis Beaupre, Michel Pigeon, Caroline Talbot, Martin Gendreau, D. R. MorganAbstract:American Society for Testing and Materials (ASTM) C 672 deicer salt scaling tests were carried out on both dry- and wet-mix shotcretes. Twenty-five dry-mix shotcretes and eleven wet-mix shotcretes were used to fabricate different test panels. The mix variables included cement type, silica fume, latex, polypropylene and steel fibers, and set-accelerating and air-Entraining Admixtures. All test panels were wet-cured for 7 days except two additional panels, one of which was not cured and the other of which was cured with a curing compound. Water containing 2.5 or 3 percent salt solutions was used for the scaling tests. The scaling residues were collected and weighed to evaluate deterioration. The mass of scaling residues was found to vary between 0.1 and 24.0 kg/m. These tests indicate that the scaling resistance of both dry- and wet-mix shotcrete improves with an increase in the air content, and that the use of silica fume generally reduces the mass of scaling residues. These tests also indicate that the use of a set-accelerating Admixture can significantly reduce the scaling resistance of shotcrete. The use of Type 30 cement and of an air-Entraining Admixture was found to markedly improve the scaling resistance of dry-mix shotcretes.
A El A Damatty - One of the best experts on this subject based on the ideXlab platform.
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performance of rice husk ash produced using a new technology as a mineral Admixture in concrete
Cement and Concrete Research, 2003Co-Authors: Moncef L Nehdi, J Duquette, A El A DamattyAbstract:This article investigates the use of a new technique for the controlled combustion of Egyptian rice husk to mitigate the environmental concerns associated with its uncontrolled burning and provide a supplementary cementing material for the local construction industry. The reactor used provides efficient combustion of rice husk in a short residency time via the suspension of processed particles by jets of a process air stream that is forced though stationary angled blades at high velocity. Investigations on the rice husk ash (RHA) thus produced included oxide analysis, X-ray diffraction, carbon content, grindability, water demand, pozzolanic activity index, surface area, and particle size distribution measurements. In addition, concrete mixtures incorporating various proportions of silica fume (SF) and Egyptian RHA (EG-RHA) produced at different combustion temperatures were made and compared. The workability, superplasticizer and air-Entraining Admixture requirements, and compressive strength at various ages of these concrete mixtures were evaluated, and their resistance to rapid chloride penetrability and deicing salt surface scaling were examined. Test results indicate that contrary to RHA produced using existing technology, the superplasticizer and air-Entraining agent requirements did not increase drastically when the RHA developed in this study was used. Compressive strengths achieved by concrete mixtures incorporating the new RHA exceeded those of concretes containing similar proportions of SF. The resistance to surface scaling of RHA concrete was better than that of concrete containing similar proportions of SF. While the chloride penetrability was substantially decreased by RHA, it remained slightly higher than that achieved by SF concrete.
