Abstract
The last unsolved problem on durability of Autoclaved Aerated Concrete (AAC) is carbonation. Water-repellent AAC showed twice as much carbonation resistance as the normal AAC under accelerated carbonation conditions. No particular difference in chemical composition, BET specific surface area, pore size distribution by mercury porosimeter and XRD patterns were observed between water-repellent AAC and the normal AAC. Also equilibrium moisture content of water-repellent AAC was lower than that of the normal AAC at 80%R.H. or less but was almost the same around 90%R.H. However it was found that, in cooling DSC, the exothermic peak intensities of water-repellent AAC were remarkably smaller than those of the normal AAC. The reason of the carbonation resistance of water-repellent AAC was attributed to the hydrophobic hydration of adsorbed water vapour by the hydrophobic groups originated from the silicone-oil.
