Study on Chloride Penetration Resistance of Mortar Using Shirasu as Cement Replacement Material

This study aims to evaluate the effect of Shirasu substitution on the chloride penetration resistance in OPC paste and mortar. To evaluate said effect, a salt water immersion test was carried out. The results showed that use of Shirasu promotes high chloride resistance. This was considered to be due to the pozzolanic reaction leading to the formation of new hydrates and hence densification of the matrix and fixation of chloride ion. The pozzolanic reaction rate increased under saline condition. Further, higher content of fine particles in Shirasu was found to result in higher pozzolanic reaction rate and chloride resistance.