Investigation of factors influencing the expansive behaviour, compressive strength and modulus of rupture of alkali–silica reactive concrete using laboratory concrete mixes

Alkali–silica reaction (ASR) in concrete results in expansion of the concrete and possibly severe cracking. The cracking leads to a reduction in the compressive strength and the modulus of rupture of the concrete. A test programme is under way on model structural elements that are suffering from ASR. As a prelude to this, a series of ASR concrete mixes were developed. This Paper examines the performance of these ASR mixes with respect to normal mixes, and comments on factors that were found to influence their compressive strength, expansion and modulus of rupture. Time-dependent variation in these factors is identified and assessed. The mixes used consisted of flint gravel, ordinary Portland cement, fused silica as a reactive aggregate and potassium hydroxide to increase the supply of alkalis in the mix. As well as the quantities of these materials, the particle size distribution of the fused silica was varied, as was the environment in which the concrete was cured and stored.