Influence of ground waste expanded perlite on the reaction of siliceous aggregates with sodium and potassium hydroxides

Paper presents results of investigation on the influence of ground waste expanded perlite on the mitigation of alkali – silica reaction in cement mortars. Crushed quartz glass was used as model reactive aggregate. Natural reactive aggregate containing radiolarite was also used. Obtained results showed, that addition of ground waste expanded perlite to mortars containing reactive aggregates resulted in significant reduction of alkali – silica reaction. Expansion of mortars soaked in sodium hydroxide at elevated temperature, according to modified ASCT C1260 test was markedly lower comparing reference samples without perlite addition. Examination of mortars and pastes with ground waste expanded perlite addition confirmed its pozzolanic properties. Increased C-S-H phase content together with decreased permeability of the mortars and decreased calcium hydroxide content are most probably the reasons for better durability of perlite bearing mortars towards alkali – silica reaction.