A MECHANISM OF AUTOGENOUS SHRINKAGE OF CEMENTITIOUS MATERIALS

摘要

Recent concrete technology put a strong emphasis on so-called high-performance concrete with a low water-cement ratio. However, these high performance concretes have some problems. One of the problems is early-age cracking due to autogenous shrinkage. In this paper, the mechanisms of autogenous shrinkage of cement paste with different water-cement ratios are investigated in relation to both the combined water due to hydration of cement and the internal relative humidity of cement systems. As the results show, it seems that the effect of the water-cement ratio on autogenous shrinkage cannot be explained with the capillary tension effect. It may be closely related to the chemical potential of the solvent in cement systems, or there is also a possibility that it occurs due to the influence of the contraction of calcium silicate hydrate gel.