Behavior of Chlorine in Cement Manufactured from Municipal Wastes

Cement manufactured from incinerator ash has been developed in Japan. This cement contains 15-20% of C3A and 0.02-0.1% of chlorine. Since the chlorine content of this cement is higher than that of normal portland cement in Japan, there is a concern whether steel bars embedded in concrete using this cement would become rapidly corroded. In this study, the behavior of chlorine in cement hydrates is investigated in terms of the contents of chlorine accommodated by Friedel's salt. The compositions of pore solution in cement hydrates at early ages and the water-soluble and acid-soluble compositions of cement hydrates are analyzed. As a result, it is found that the concentration of chloride ion in pore solution of cement hydrates using cement manufactured from municipal wastes is not too high. It means that many chloride ions could be accommodated by Friedel's salt because of high C3A content.