Effect of alkali–silica reaction on the mechanical properties of concrete with and without pozzolan

Purpose This work presents the results of an extensive experimental campaign with 240 concrete specimens, with and without pozzolan additive, to assess the effects of internal expansion reactions on the strength and deformation properties of structural concrete due to alkali-silica reactions. Design/methodology/approach The samples were submerged in a 1 N NaOH solution for 242 days at a constant temperature of 60°C, after being exposed for 30 days to a 1 N NaOH solution at 80°C. The concrete mixtures incorporated two types of cement: PC-V (additive-free) and PC-IV (with a higher concentration of pozzolanic additives). The only source of reactivity in the aggregates used comes from the coarse aggregate, which is highly reactive microcrystalline and macrogranular quartz. The design compressive characteristic strength of the concrete was set at 35 MPa. Findings The results obtained show that the internal expansion reactions had different impacts on the mechanical properties of the concrete, with the modulus of elasticity being the most influenced and the least sensitive to the type of cement used. PC-IV and PC-V samples exhibited a drop of 36% and 38% in the respective modulus of elasticity. For compressive strength, PC-IV samples had a greater loss in compressive strength value than those made with cement without addition, −6.8% and −18.6%, respectively. Originality/value This is one of the first studies with such an extensive experimental campaign to analyze the effect of internal expansion reactions on the mechanical properties of concrete with and without pozzolan, and thus fill an existing gap in the literature.