Abstract
Formerly, the experimental data indicating the expansion of Laumontite contained concrete under seawater environments is reported. However, the expansion mechanism or factors affecting the expansion are not clarified. In this study, through the analysis of expansively deteriorated old concrete, the cause of the expansion is confirmed to be the ettringite formation inside concrete. Furthermore, through the expansive test of mortar specimens, including several different factors, the following conclusions are obtained. Cement type or steam curing has no significant effect on the expansion generation and its magnitude. However, seawater supply to concrete surface is indispensable to generate the expansion of concrete.
