膨胀剂和含水率对预拌补偿收缩混凝土微观结构的影响与分析

In order to study the effect of expansive agent dosages and the sand moisture contents on the microstructure of the ready-mixed shrinkage-compensating concrete. The microstructure experiments with the storage period of 7days in 5 kinds of expansive agent dosages (0%, 4%, 6%, 8% and 10%) and 3 kinds of sand moisture contents (0.5%, 1.0% and 1.5%) were conducted. The results show that the number of internal structural holes and micro cracks of the concrete reduced constantly with the increase of expansive agent dosages from 0% to 6%.The micro interface between the C-S-H gel and Ca(OH)2 crystal and large numbers of internal voids in the micro interface were filled, generated a relatively uniform homogeneous continuum; when the expansive agent dosage was equal to 8% or 10%, new micro cracks were induced due to the too much expansive property in the concrete, resulted in the increase of the porosity and the decrease of the compactness. With the increase of the water contents in dry-mixed materials, the cohesiveness between the C-S-H gel and Ca(OH)2 crystal declined gradually, and the number of holes increase, which leaded to the increase of the porosity and the decrease of the compactness.