R. Abbasnia, M. Kanzadi, M. Shekarchi Zadeh, J. Ahmadi,
Volume 7, Issue 2 (June 2009)
Abstract
Drying shrinkage in concrete, which is caused by drying and the associated decrease in moisture content, is
one of the most important parameters which affects the performance of concrete structures. Therefore, it is necessary
to develop experimental and mathematical models that describe the mechanisms of drying shrinkage and damage build
up in concrete. The main objective of this research is the development of a computational model and an experimental
method for evaluation of concrete free shrinkage strain based on the internal moisture changes. For this purpose and
for modeling of moisture losses in concrete members a computational program based on finite element approach and
the modified version of Fick's second law in which the process of diffusion and convection due to water movement are
taken into account, is developed. Also the modified SDB moisture meter was used to measure the internal moisture
changes in concrete. Based on the obtained results, calculated humidity is in good agreement with measured data when
modified Fick's second law with diffusion coefficient from Bazant method were used, and are very reasonable for
determining the moisture gradient. Also, the predicted value of shrinkage strain from the proposed method is in good
agreement with measured data and also the established relationship can be used for determine the distribution of
shrinkage strains in concrete members.