TY - GEN
T1 - Analytical and quantitative aspects of surface moisture transport and plastic shrinkage cracking
AU - Mobasher, B.
AU - Bakhshi, M.
AU - Yao, Y.
N1 - Publisher Copyright:
© ICDCS 2018. All rights reserved.
PY - 2018
Y1 - 2018
N2 - The drying rate of porous materials such as hydrating cement paste during early hydration stages is studied using analytical and experimental procedures. Effects of micro and macro fibers as they change the nature of restrained shrinkage cracking are also documented. A methodology based on vacuum drying experiments is developed to measure the rate of evaporation from the surface of fresh paste and mortar mixtures that leads to restrained shrinkage cracking. Stages of microcrack coalescence due to plastic shrinkage cracking are quantitatively analyzed using digital image correlation. A model for internal moisture transfer simulates initial constant drying rate followed by a vapor diffusion transport phenomena. A fluid mechanics approach for water evaporation from the boundary-layer in terms of mass transfer, diffusion, and convection is used. Effect of temperature, wind speed, and relative humidity are studied. Results of these two experiments are then integrated with an analytical approach for the restrained ring specimen which correlates the moisture diffusion in the specimen with the rate of evaporation and shrinkage strain. The model incorporates key influential parameters of diffusion, evaporation, shrinkage, creep, aging, and microcracking, in the stress analysis of a restrained concrete section. The formulation addresses the effect of geometry of the specimen, the humidity and shrinkage conditions, and the restraint offered by stiffness of the steel ring. Finally the modelling is extended to simulate a slab on ground and predict multiple transverse cracking as well as slab curling using a finite difference model.
AB - The drying rate of porous materials such as hydrating cement paste during early hydration stages is studied using analytical and experimental procedures. Effects of micro and macro fibers as they change the nature of restrained shrinkage cracking are also documented. A methodology based on vacuum drying experiments is developed to measure the rate of evaporation from the surface of fresh paste and mortar mixtures that leads to restrained shrinkage cracking. Stages of microcrack coalescence due to plastic shrinkage cracking are quantitatively analyzed using digital image correlation. A model for internal moisture transfer simulates initial constant drying rate followed by a vapor diffusion transport phenomena. A fluid mechanics approach for water evaporation from the boundary-layer in terms of mass transfer, diffusion, and convection is used. Effect of temperature, wind speed, and relative humidity are studied. Results of these two experiments are then integrated with an analytical approach for the restrained ring specimen which correlates the moisture diffusion in the specimen with the rate of evaporation and shrinkage strain. The model incorporates key influential parameters of diffusion, evaporation, shrinkage, creep, aging, and microcracking, in the stress analysis of a restrained concrete section. The formulation addresses the effect of geometry of the specimen, the humidity and shrinkage conditions, and the restraint offered by stiffness of the steel ring. Finally the modelling is extended to simulate a slab on ground and predict multiple transverse cracking as well as slab curling using a finite difference model.
KW - Cracking
KW - Diffusion
KW - Drying
KW - Modeling
KW - Moisture transport
KW - Restrained shrinkage
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M3 - Conference contribution
AN - SCOPUS:85079090138
T3 - 6th International Conference on Durability of Concrete Structures, ICDCS 2018
SP - 74
EP - 82
BT - 6th International Conference on Durability of Concrete Structures, ICDCS 2018
A2 - Basheer, P. A. Muhammed
PB - Whittles Publishing Limited
T2 - 6th International Conference on Durability of Concrete Structures, ICDCS 2018
Y2 - 18 July 2018 through 20 July 2018
ER -