Prediction of Free Shrinkage Strain Related to Internal Moisture Loss

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.