Combined use of Class F fly ash and lithium salt for the reduction of alkali-silica reactivity

Abstract

The damages due to Alkali-Silica Reactivity (ASR) controlled by fly ash alone may sometimes require its high dosage, which impacts the early strength of concrete, and those suppressed by lithium alone increase the construction costs. This study reports on the effectiveness of the combination of lithium salt and fly ash in reducing alkali-silica reactivity of reactive aggregates. In addition, lithium salt or fly ash was used to produce secondary control mixtures. For comparison purpose, mortars without having fly ash or lithium, used as primary control mixtures, were also evaluated. The expansion of the test mortar bars was evaluated based on the failure criteria of ASTM C 1260, and compared with that of the control mortars at 14, 28 and 56 days. An analytical model was introduced to determine the expansion of the mortar bars containing both fly ash and lithium from the expansion of the mortar bars containing fly ash or lithium.