Unit Processes of Shrinkage Behavior Based on Dynamical Analysis of Cement Paste in Different Maturity

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Title: Unit Processes of Shrinkage Behavior Based on Dynamical Analysis of Cement Paste in Different Maturity

Author(s): E. Tazawa

Publication: Special Publication

Volume: 220

Issue:

Appears on pages(s): 83-98

Keywords: autogenous shrinkage; curing time; drying shrinkage; dynamic analysis; hydration of cement; mechanism; transition points; unit processes; weight change

Date: 3/1/2004

Abstract:
Investigation into the mechanism of shrinkage is essential for the engineering purposes to mitigate cracking of concrete structures. Because comprehensive analysis of unit processes of self deformations is inevitable for systematic understanding of interaction between various self deformations, such as drying shrinkage, autogenous shrinkage and thermal deformation etc.,or their influences on stress generation and crack extension or crack propagation. In this paper one example of this trial is presented based on analysis of relationship between weight loss and drying shrinkage measured by ASTM method. By this analysis, it is shown that unit processes involved in these physical phenomena are not so simple as can be stated by Fick's diffusion theory. Depending upon duration of underwater curing or degree of hydration, unit processes are drastically varied suggesting that variation in microstructure gives rise to quite different situations for desiccation and deformation. Based on these models, relation and interaction between drying shrinkage and autogenous shrinkage is discussed.