Experimental and numerical study of long-term alkali-silica reaction (ASR) expansion in mortar with recycled glass

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Recycled glass has been demonstrated to be a sustainable alternative for sand in concrete, which can tackle the stockpiling of waste glass and shortage of natural aggregate. However, alkali–silica reaction is the major impediment to its wide adoption where more research is required. This paper examined the long-term ASR expansion of mortar containing glass from experimental and numerical analyses. In the experimental study, the effect of glass size (0.15–0.3 mm, 0.3–0.6 mm, 0.6–1.18 mm, 1.18–2.36 mm, 2.36–4.75 mm), glass content (25%, 50%, 75%, 100% by mass) and curing temperature (38 °C, 60 °C 80 °C) were investigated. The accelerated ASR expansion tests were conducted in the elevated temperature and boosted alkali supply. Experimental results showed that the size fraction 1.18–2.36 mm caused the highest ASR expansion, and the size fractions smaller than 0.6–1.18 mm was found to be innocuous. Besides, ASR expansion increased as glass content increased. Furthermore, ASR kinetic was slower and final expansion reduced when temperature decreased. To provide insights into the ASR expansion behaviours, a novel meso-scale chemical-mechanical model was proposed in this study. In the numerical model, the tested specimens were modelled as a three-phase composite including the matrix, glass aggregate and interfacial transition zone. The mechanical and chemical components in the model were calibrated and validated by uniaxial compression and ASR expansion tests. The validated model not only can accurately predict the ASR expansion but also reveal that internal damage became more homogeneous with increasing content of reactive aggregate.