Abstract:In order to study the performance deterioration and damage of ALC after high temperature treatment under different cooling methods,ultrasonic nondestructive test, static mechanical properties test and capillary water absorption test was used to investigate the effects of temperature and cooling methods on mass loss rate, longitudinal wave velocity, compressive strength, elastic modulus, stress-strain relationship, energy loss and capillary water absorption of ALC specimens treated by different temperatures and cooling methods .The results show that all kinds of hydration products in ALC are decomposed by heating, water dissipating, volume expanding, microcracks increasing, longitudinal wave velocity decreasing, compressive strength decreasing, elastic modulus decreasing, plasticity increasing, peak strain increasing, energy dissipation increasing and maximum capillary water absorption increasing. The shape of stress-strain curve is similar to that of ordinary concrete, which has gone through compaction stage, elastoplastic stage, failure stage and residual stage. Compared with the natural cooling specimen, the spray cooling specimen has less damage before 300℃, and the performance degradation degree is lower. The degradation damage increases obviously at 300~600℃, and the capillary water absorption increases significantly. The influence of different cooling methods on ALC performance decreases gradually at 600~800℃. It is concluded that different cooling methods have certain influence on ALC after high temperature treatment, but with the increase of temperature, the influence gradually weakens.