Abstract:Initial surface absorption test(ISAT) method was employed to investigate the water sorptivity of steam curing concrete as well as the effects of binder types, curing condition and steam curing technology on capillary absorption coefficient of concretes. The corresponding mechanisms and technical measurements reducing capillary absorption role of steam curing concrete were studied. Results indicate that, compared with standard curing concretes, a much higher water absorption gradient from exposure surface to interior of steam curing concretes is observed, which results from the bad effects of elevated temperature on the top surface directly exposed to steam during steam curing period. The capillary absorption coefficient of steam curing concrete and the corresponding gradient of capillary absorption from exposure surface to interior both can be decreased by incorporating a compound of fly ash and slag or silica fume, using such technical measurements as subsequent water curing and/or water retaining coverage.