Effect of Crystallinity on Properties of Autoclaved Aerated Concrete Matrix Materials

Abstract

Abstract The properties of Autoclaved Aerated Concrete (AAC) are related to the crystallinity of hydration products of matrix materials. This study describes the effects of tobermorite and C-S-H gel contents in hydration products of AAC matrix materials on mechanical and drying shrinkage properties. In this study, the mass contents of tobermorite and C-S-H gel were semiquantitative calculated By XRD and nitrogen adsorption method respectively. According to the data obtained from the orthogonal design, the influences of the contents of tobermorite and C-S-H gel on the mechanical properties and drying shrinkage were analyzed, and the optimum mass ratio of tobermorite to C-S-H gel was determined. The factors affecting the crystallization of AAC matrix materials were investigated. The results manifest that the matrix material has higher compressive strength, higher flexural strength and smaller drying shrinkage when the tobermorite content is 0.18~0.23, and the C-S-H gel content is 0.440~0.500. The fineness of quartz sand is the primary factor affecting the performance of AAC matrix materials, followed by constant temperature time, calcium-silica ratio and cement-lime ratio. The research results provide a reference for predicting or designing the performance of AAC.