The Experts below are selected from a list of 21096 Experts worldwide ranked by ideXlab platform
Chang-geun Cho - One of the best experts on this subject based on the ideXlab platform.
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Effect of fiber addition on fresh and hardened properties of spun Cast Concrete
Construction and Building Materials, 2016Co-Authors: Hyeong-ki Kim, Jeong Gook Jang, Min-ju Lim, Chang-geun ChoAbstract:Abstract The effect of fiber addition on the properties of fresh and hardened Concretes Casted by centrifugation was investigated. Workability of fresh Concrete mixtures, sludge bleeding after centrifuging, and mechanical properties of hardened Concrete including compressive and splitting tensile strengths and modulus of elasticity were examined. Post-crack behavior of spun Cast Concrete was investigated by splitting tensile testing. Considering sanitary sewer environments, Concrete resistances against sulfuric acid erosion and sulfate expansion were evaluated. Although the addition of low fiber fractions (below 0.15 vol.%) did not significantly affect workability and strength of the spun Cast Concretes, it enhanced their toughness and resistance against sulfate expansion.
Toshiharu Kishi - One of the best experts on this subject based on the ideXlab platform.
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Long-term permeability measurements on site-Cast Concrete box culverts
Construction and Building Materials, 2019Co-Authors: Kenichiro Nakarai, Koichiro Shitama, Sohei Nishio, Yuya Sakai, Hiroshi Ueda, Toshiharu KishiAbstract:Abstract This study investigated the effect of age on transport property measurements of Concrete cover. Changes in moisture contents, air permeability, and water sorptivity were monitored for three years by conducting non-destructive tests on surfaces of site-Cast Concrete box culverts and mock-up specimens. Furthermore, carbonation rates in the specimens were measured. The results revealed that transport properties measured by non-destructive tests were effective at detecting effects of cement types and curing periods on the carbonation progress. In particular, the air permeability coefficients of specimens with lower moisture contents at later ages showed high correlation with the carbonation rates.
Virpi Leivo - One of the best experts on this subject based on the ideXlab platform.
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Drying of in situ Cast Concrete ground slabs and covering criteria
Building and Environment, 2009Co-Authors: Jukka Rantala, Virpi LeivoAbstract:The main objective of this paper was to examine the overall moisture behaviour of an in situ Cast Concrete ground slab during the initial drying period of the fresh Concrete from Casting to flooring. This article describes and evaluates various methods to measure moisture levels in Concrete slabs in order to decide if flooring can be attached. The most accurate method is verified against measurements and compared with calculations. Many of the methods only consider the surface moisture content of the slab and do not consider the moisture condition deep in the slab. According to performed laboratory tests and FE modelling, moisture content of the slab surface is not a reliable indicator of the overall moisture conditions of the slab. Residual moisture deep in the slab has a major effect on the moisture distribution at the slab cross-section after flooring. The only reliable method to determine the moisture conditions in a new Concrete ground slab before flooring is to measure the moisture content at the equivalent depth of the slab. It reliably predicts the ultimate moisture content at slab/flooring interface after flooring. A ground slab is drying in two directions: towards the indoor air by evaporation from the slab surface, and towards the cooler subsoil layers by diffusion. The significance of drying downwards increases after the flooring assembly.
István Bódi - One of the best experts on this subject based on the ideXlab platform.
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SERVICE LIFE ESTIMATION OF PRE-Cast Concrete STRUCTURAL MEMBERS
Pollack Periodica, 2009Co-Authors: Kálmán Koris, István BódiAbstract:The determination of service life of Concrete structural members is an important aspect of durability design. The scope of the paper is to present an effective and easy to use method for the estimation of service life of pre-Cast Concrete structural members. A stochastic approach using stochastic finite element method was applied during the analysis. The effect of creep, shrinkage, relaxation, carbonation induced corrosion and deterioration of cross-sectional sizes on the mean value and standard deviation of bending moment resistance, as well as the change of load effect in time were taken into account during the calculations. The results of probabilistic analysis were compared to results of bending tests that were carried out on pre-stressed Concrete beams. The use of the introduced method for the purposes of service life estimation is also presented in case of a long-span, pre-Cast, pre-stressed Concrete beam. Initial stochastic parameters of material properties and structural geometry were derived from...
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Long-term analysis of bending moment resistance on pre-Cast Concrete beams
Periodica Polytechnica Civil Engineering, 2009Co-Authors: Kálmán Koris, István BódiAbstract:Durability design of structures is an important part of the design process. A possible method for the durability design is the probabilistic approach considering changes of structural resistance and the load effect during a certain time period. In order to determine stochastic parameters of structural resistance as a function of time, deterioration of materials and the decrease of structural sizes due to environmental effects must be predicted. This paper is mainly focusing on the analysis of the bending moment resistance of pre-Cast Concrete beams as a function of time. The effect of creep, shrinkage, relaxation, carbonation induced corrosion and deterioration of cross-sectional sizes on the mean value and standard deviation of bending moment resistance were considered. The performed calculation method is illustrated by numerical example on a pre-Cast, prestressed Concrete beam. In case of the presented beam, the mean value of bending moment resistance decreases 4-6% and its standard deviation increases 200- 350% after 100 years depending on the relative ambient humidity. Results concerning mean value and standard deviation of structural resistance can be used for the purposes of probabilistic durability design. Considering the same safety level as in Eurocode 2, the introduced probabilistic design method delivers about 10% higher load carrying capacity as the application of relevant Eurocode 2 standard in case of the presented beam.
Vivek Bindiganavile - One of the best experts on this subject based on the ideXlab platform.
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thermal properties of lightweight dry mix shotcrete containing expanded perlite aggregate
Cement & Concrete Composites, 2014Co-Authors: Derek B Apel, Vivek BindiganavileAbstract:Abstract This paper describes the thermal properties of lightweight dry-mix shotcrete using expanded perlite aggregate (EPA). Mixes made with different EPA/sand ratios were sprayed through the dry-mix shotcreting technique onto wooden molds to produce panels for mechanical and thermal testing. The density, uniaxial compressive strength (UCS), splitting tensile strength (STS), and the ultrasonic pulse velocity (UPV) were measured at various ages. Further, the ISO approved transient plane source (TPS) technique was employed to measure the thermal properties at 28 days. The results illustrate that shotcrete mixes with EPA have similar UCS and superior STS compared to Cast Concrete. Adding EPA led to a drop in thermal conductivity and diffusivity. When compared with Cast Concrete, shotcrete had lower specific heat capacity. This study found dry-mix shotcrete incorporating EPA at up to 75% sand substitution as a mechanically viable and thermally resistant alternative to Cast Concrete containing regular aggregates.