Mechanism of leaching inhibition of cementitious materials due to hydrogenecarbonate ion in groundwater

Upgrading durability-performance evaluation technique for concrete is urgently demanded in connection to its application to radio-active waste repository which needs ultra long-term durability. The purpose of this research is to evaluate the effects of groundwater components on the leaching of cementitious materials. This paper presents the results of an experimental study on the effects of hydrogencarbonate in immersion solution on leaching of cementitious materials as the initial step of the study. It was clarified that hydrogencarbonate reacted with calcium leached from specimen to form a calcite layer on the surface of specimen, which inhibited leaching of cementitious materials. It was found that the higher the concentrations of sodium hydrogencarbonate, the less cementitious materials were leached. (author)