Effect of alkali silica reaction on aging mortar bars

The focus of this study is the Alkali Silica Reaction (ASR) effect on mortar. Several tests and procedures are currently available to evaluate this reaction, particularly in terms of reactivity of the aggregate. However, data given in the literature concerning the effect of ASR on the mechanical properties of concrete and mortar is scattered and practically no information is available for some properties such as fracture energy. In this study, the mechanical properties of mortar were evaluated and monitored, under normal and accelerated environmental conditions. The fracture energy, the compressive strength and the tensile strength were identified for mortar specimens, casted with highly reactive SPRATT crushed aggregate, at two different temperatures (23C and 80C) and at two different alkali concentrations (immersed in water and in 1N NaOH solution). Moreover, free expansion tests were also performed, according to ASTM C1260, along with petrographic observations, in order to relate them to the evolution of the mechanical properties of mortar. Results show a decrease of the mechanical properties of mortar, associated to the specimens in 80C in the alkali solution. However, this study reveals deterioration due to ASR is counter-balanced by the strength build-up resulting from the hydration process.