Fundamental Study on Low-Temperature Autoclaving Focused on the Water Cement Ratio and Silica Fume Content

This paper describes a fundamental study conducted for establishing a technique of low-temperature autoclave curing, with the focus placed on the water cement ratio and silica fume content. The experimental results showed that silica fume-added specimens cured at 150°C had similar compressive strength to those cured at 180°C. The low-temperature autoclave curing was made possible by the addition of silica fume which increased the gel porosity and reduced the total porosity through accelerated pozzolanic reaction. In addition, the gel porosity did not show significant change against the autoclave curing temperature in the presence of silica fume. This was considered to be the key factor in the mechanism of low-temperature autoclave curing. It was also demonstrated in this study that the presence of tobermolite was not an essential requirement for the high strength development in which C-S-H played a predominant role.