Influence of fineness of ground recycled glass on mitigation of alkali–silica reaction in mortars

•The effect of fineness of glass powder (GP) on ASR mitigation ability was evaluated.•The benefits of using GP as both SCM and as an aggregate material to mitigate ASR were evaluated.•Microstructural studies were conducted to determine the nature of distress in test specimens.•GP when used as an aggregate material showed significant benefits in mitigating ASR. The use of waste glass, both as a crushed glass aggregate and in a finely ground form, as a pozzolanic material in concrete has been extensively studied in the past. However, the combined use of finely ground glass powders with crushed glass aggregates has not been previously explored, as this presents a unique opportunity to not only maximize the use of waste glass in concrete but also potentially address the alkali–silica reaction issues, often associated with the use of crushed glass aggregates in concrete. This study focused on studying the influence of fineness of glass powder in mitigating alkali–silica reaction in mortar specimens containing crushed glass aggregate and a natural reactive aggregate. In these studies the glass powders were used both as a cement replacement material and as an aggregate replacement material. Two different fineness of glass powder were evaluated in this study, with an average particle size of 17 and 70microns. Mortar bars prepared with glass powder as aggregate replacement material at 10%, 20% and 30% replacement levels were evaluated in the standard ASTM C1260 test method. Mortar bars prepared with glass powder as cement replacement material at 10% and 20% were evaluated in the standard ASTM C1567 test method. The results from these studies showed that the finer glass powder showed significantly improved ability to mitigate ASR, particularly when used as an aggregate replacement material, both in the case of crushed glass and natural reactive aggregates. This study shows that an aggregate comprised of 100% glass material can be produced without any deleterious consequences of alkali–silica reaction, provided sufficient quantity of fine glass powder is used in the mixture.