Use of ternary blends containing silica fume and fly ash to suppress expansion due to alkali–silica reaction in concrete

Abstract

This paper investigates the effects of cementitious systems containing Portland cement (PC), silica fume (SF) and fly ash (FA) on the expansion due to alkali–silica reaction (ASR). Concrete prisms were prepared and tested in accordance with the Canadian Standards Association (CSA A23.2-14A). Paste samples were cast using the same or similar cementitious materials and proportions that were used in the concrete prism test. Pore solution chemistry and portlandite content of the paste samples are reported. It was found that practical levels of SF with low-, moderate- or high-calcium FA are effective in maintaining the expansion below 0.04% after 2 years. Pore solution chemistry shows that while pastes containing SF yield pore solutions of increasing alkalinity at ages beyond 28 days, pastes containing ternary blends maintain the low alkalinity of the pore solution throughout the testing period (3 years).