Synopsis
It is known that sodium chloride from the surrounding solution promotes the expansive alkali-silica reaction in cementitious materials, and that the incorporation of pozzolanic materials suppresses the expansion caused by the intrusion of alkali salts. However, the mechanisms responsible for these phenomena are not fully understood. In this paper, substantial differences in expansion behaviour between mortars(made with a high-alkali OPC, nine fly ashes at replacement levels of 0, 10, 20 and 30%, and Beltane opal fine aggregate) immersed in I N NaOH and I N NaCl solutions are discussed, taking account of the composition of the pore solutions extracted from the mortars. Mechanisms for the initiation and acceleration of the alkali-silica expansion in mortars exposed to the NaCl solution are also discussed.
