The Experts below are selected from a list of 15930 Experts worldwide ranked by ideXlab platform
Kimberly E. Kurtis - One of the best experts on this subject based on the ideXlab platform.
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a probabilistic technique for entrained air void analysis in Hardened Concrete
Cement and Concrete Research, 2014Co-Authors: Nathan P Mayercsik, Robert Felice, Tyler M Ley, Kimberly E. KurtisAbstract:A novel method that utilizes the lineal-path function to ascertain a probability density function for the three-dimensional size distribution of entrained air voids directly from plane polished sections of Hardened Concrete is proposed. The results then treat the spacing factor in terms of a probabilistic maximum distance from a random point in the cement paste matrix to the periphery of an air void, where air voids are treated as a polydispersed sphere system. The model was applied to Concretes with various air entrainment admixture types and dosages. The results suggest that the model may offer a better assessment of the system for use in assessing durability and studying admixtures, as well as providing a new tool for spatial characterization of heterogeneous and porous materials.
G De Schutter - One of the best experts on this subject based on the ideXlab platform.
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automated air void analysis of Hardened Concrete a round robin study
Cement and Concrete Research, 2006Co-Authors: U Jakobsen, C Pade, O Magnusson, S De Buck, N. Thaulow, S. Sahu, D Brown, G De SchutterAbstract:Abstract The RapidAir is an automatic system for analysing the air void content of Hardened Concrete. The analysis requires polishing of the Concrete surface as described in ASTM C 457 as well as a contrast enhancement of the surface. The system can automatically analyse the air void system according to the ASTM C 457 and EN 480-11 standards. The sample preparation includes contrast enhancement steps ensuring white air voids in black Concrete (aggregate and paste). For a well-lapped sample of good quality Concrete the contrast enhancement procedure requires approximately 5–10 min to perform. The air content can be analysed in less than 15 min traversing 2413 mm (95 in.) — a significant improvement compared to several hours normally required to perform a manual linear traverse analysis. This paper describes the method and technique required for automatic analysis using the RapidAir system as well as data from a Round Robin study. Three samples were circulated to 7 different laboratories for automatic air void analysis. Prior to the automatic analysis the samples were analysed manually using linear traverse and point counting methods. The results of the Round Robin study showed very good repeatability and reproducibility of the RapidAir system but large variations when using manually performed analysis.
Mehmet Emin Koc - One of the best experts on this subject based on the ideXlab platform.
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influence of ground pumice on compressive strength and air content of both non air and air entrained Concrete in fresh and Hardened state
Construction and Building Materials, 2018Co-Authors: Fatih Ozcan, Mehmet Emin KocAbstract:Abstract Study investigates the influence of ground pumice (GP) addition on compressive strength and air content of air entrained and non-air entrained Concrete. Control Portland cement Concrete was prepared by keeping the binder amount at 400 kg/m3 with water binder (W/B) ratio 0.45. Air entrained Portland cement Concrete mixtures were also prepared by addition of 0.025%, 0.05% and 0.075% air entraining agent (AEA) dosages to control Portland cement Concrete. All Portland cement Concretes mixtures were modified by inclusion of 10%, 15%, 20% and 25% GP as cement replacement in mass basis, and then Concretes containing ground pumice were obtained. Air contents of all fresh Concretes were measured. Entrained air void area values on cut surface of Hardened Concrete were determined by image processing technique. Increase in air entraining agent dosage content in fresh Concrete exhibited an increase not only in air content but also flow diameter value of fresh Concrete. Addition of ground pumice as a cement replacement in Concrete caused reduction in air content and flow diameter, however, it increased compressive strength of air entrained Concrete. Compressive strength values related inversely with the air contents of fresh Concrete as well as air void area values of Hardened Concrete computed by image processing technique. Air contents of fresh Concrete and image processing void area values of Hardened Concrete has shown a good relationship between themselves. Image processing can be used to measure air content of Hardened Concrete.
Parviz Soroushian - One of the best experts on this subject based on the ideXlab platform.
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mechanical properties of hybrid fiber reinforced lightweight aggregate Concrete made with natural pumice
Construction and Building Materials, 2011Co-Authors: Nicolas Ali Libre, Mohammad Shekarchi, Mehrdad Mahoutian, Parviz SoroushianAbstract:Abstract The purpose of this study is to improve the ductility of pumice lightweight aggregate Concrete by incorporating hybrid steel and polypropylene fibers. The changes in mechanical properties and also bulk density and workability of pumice lightweight aggregate Concrete due to the addition of hybrid steel and polypropylene fibers have been studied. The properties were investigated include bulk density and workability of fresh Concrete as well as compressive strength, flexural tensile strength, splitting tensile strength and toughness of Hardened Concrete. Nine Concrete mixtures with different volume fractions of steel and polypropylene fibers were tested. A large increase in compressive and flexural ductility and energy absorption capacity due to the addition of steel fibers was observed. Polypropylene fibers, on the other hand, caused a minor change in mechanical properties of Hardened Concrete especially in the mixtures made with both steel and polypropylene fibers. These observations provide insight into the benefits of different fiber reinforcement systems to the mechanical performance of pumice lightweight aggregate Concrete which is considered to be brittle. These results provide guidance for design of Concrete materials with reduced density and enhanced ductility for different applications, including construction of high-rise, earthquake-resistant buildings.
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dispersion of plant pulp in Concrete and use thereof
Cement & Concrete Composites, 2000Co-Authors: Parviz SoroushianAbstract:Pulp fibers derived from wood or non-wood plants or recycled paper products, which are about 0.1-30 mm long and about 0.001-0.1 mm in diameter with length-to-diameter ratio of about 30-3000, are dispersed in conventional Concrete mixtures using conventional mixing equipment for effectively improving fresh and Hardened Concrete properties at relatively low cost. Dispersion is achieved by individualizing the plant pulp fibers so that they are not fully bonded to each other, and dispersing the individual fibers in Concrete at relatively low dosages of about 0.3-30 kg per cubic meter. Once individualized, the affinity of plant pulp fibers for water facilitates their dispersion in conventional Concrete mixtures. Fresh Concrete mixtures incorporating the dispersed individualized plant pulp fibers possess desirable workability, resistance to segregation and bleeding, pumpability, finishability, and reduced rebound when pneumatically applied. Hardened Concrete materials incorporating the dispersed individualized plant pulp fibers provide improved crack resistance, toughness characteristics, impact resistance, fatigue life, abrasion resistance, and other mechanical, physical and durability characteristics. Precast and cast-in-pace Concrete as well as plain and reinforced Concrete and shotcrete benefit from such improvements in fresh and Hardened material properties rendered by dispersed plant pulp fibers.
Jan Elsen - One of the best experts on this subject based on the ideXlab platform.
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automated air void analysis on Hardened Concrete results of a european intercomparison testing program
Cement and Concrete Research, 2001Co-Authors: Jan ElsenAbstract:Abstract This paper presents the results of a European round robin test on air void analysis on Hardened Concrete (SMT-EC-research project — Contract No. SMT4-CT95-2006). Thirteen laboratories in Europe from seven countries participated in the intercomparison test of which seven used a manual method and six an automated measurement system. The results indicate that the results obtained with measuring methods using image analysis (IA) techniques all statistically lie in the group of all measurement results. The automated methods can be problematic when a high amount of porous sand grains is present in the Concrete. A second disadvantage of these automated methods is that it is not possible with the current methods being used to measure the paste content of the sample.
