セメントの水和反応によるコンクリートの収縮と空隙の測定

Abstract

The chemical shrinkage is generated, when cement reacts with water. As a skeleton is formed after setting of cement, the hardened cement body cannot shrink any more as much as the volume reduction caused by hydration. Therefore, the hydrates are compensated by the formation of voids in the microstructure. While, the macroscopic volume change, namely autogenous shrinkage depends on the rigidity of microstructure that has close relation with the morphology of hydrates. Autogeneous shrinkage is caused by self-desiccation which is the result of the formation of fine pores in the microstructure of hardened cement body and the water consumption by the hydration reaction of cement. In this paper, chemical shrinkage, autogenous shrinkage and voids, which are produced in cement paste, mortar and concrete, were measured. The volume change of specimen was measured by a new equipment and length change of specimen measured by the JCI method. The microstructure of concrete was observed with SEM. It was clear that both shrinkage ratios and the quantity of voids were closely related to an amount of cement and aggregate.