Abstract
Thaumasite formation is one of the important external sulfate attacks with leading concrete to weak tissues. The formation of thaumasite required long term, therefore, the mechanism of the formation is not unclear. Using the suspension liquid phase reaction, formation of thaumasite was investigated focusing the effect of sodium and the core of crystallization. By adding small amount of natural thaumasite in the reactor, the formation of thaumasite was markedly accelerated, and the sodium expressed the formation of thaumasite. However the presence of synthesized ettringite did not affect the formation, ettringite that is formed in the rector accelerated the formation of thaumasite. The reason of this phenomena was discussed.
