Effect of Cement Characteristics on the Setting Behavior of Autoclaved Aerated Concrete

Abstract

A cement suitable for the Autoclaved aerated concrete (AAC) was developed. The cement in which the C₃S, fineness (Blaine), and hemihydrate (H)/gypsum (G) ratio (H/(H+G)) changed was produced experimentally. Using this cement, the effect of the cementitious property on the viscosity of the AAC slurry and the hardening of the AAC green cake was clarified. Though H/(H+G) influences viscosity, C₃S and Blaine do not. On hardening, it quickens, as C₃S is more abounding as Blaine is higher, and as H/(H+G) is lower. Since the cuttable time shortens on Blaine 4300 cm²/g, and H/(H+G)=0% is not desirable. The effect of H/(H+G) on slurry viscosity and hardening was regarded as the reactivity of C₃A and generation of the ettringite. The hydration temperature of the cement in AAC is higher than ordinary cement paste, and the rapid supply of SO₄ ^2- from hemihydrate of which the solubility is high is required, since the hydration of C₃A is extremely active. The characteristic of the cement suitable for AAC consists like as follows; a) HC with many C₃S is made as a base. b) The Blaine is desirable at around 3800 cm²/g. c) Hemihydrate and gypsum are coexistence. The adaptability was confirmed by the factory scale test.