Deterioration mechanism of steam-cured concrete subjected to coupled environmental acid and drying action

Abstract

In order to investigate the deterioration mechanism of steam-cured concrete under severe environmental actions such as acid rain corrosion, salt corrosion, and cyclic thermal loading, accelerated corrosion tests were conducted in this study. Surface damage as well as deteriorative kinetics of steam-cured concrete and cement paste suffering from coupled acid-thermal actions was investigated by soaking-drying cycle experiments. The effects of mineral admixture, curing regime and corrosion condition on the durability were all comparatively studied, and the X-ray diffractograms and nanoindentation were applied to analyse the mechanism of corrosion deterioration. The results revealed that compared with the cementitious materials under standard curing, larger depth and faster corrosion were observed for steam-cured concrete and cement paste, which might be partly attributed to the lower content of hydrated production presented in steam-cured specimens. Besides, under acid solution soaking-drying cycle regime, there was significant higher corrosion depth compared to only soaking in acid solution. The corrosion depth under steam curing and soaking-drying condition increased by 156.68% and 44.17%, respectively, compared with those under standard curing and only soaking treatment. In addition, fly ash effectively decreased the corrosion depth of steam-cured cement paste and concrete by 64.98% and 16.33%, respectively.