Currently the majority of industrial companies in the world develop and implements clean production technologies where manufacturing wastes are recycled and are used for new building materials production. Due glass debris sorting and recycling are practiced at minimum level in Latvia, there should be found alternative ways how to reduce the accumulated glass wastes. The worldwide application of waste glass in concrete was quite limited due to alkali-silica reactivity (ASR) for almost forty years, but this supplementary cementitious material gained again interest in its alternative use in concrete industry in the last decade. It was found that the ground glass particles (<150 μm) initiate pozzolanic reactions without harmful expansion deformations. Size reduction of glass to enhance its chemical reactivity is the key enabling step for converting the landfill-bound waste glass into a valuable product capable of partially replacing cement in concrete. The coarse and fine aggregates can trigger ASR in concrete whereas glass powder can suppress the tendency to ASR and produce an effect similar to that of supplementary cementitious materials such as pozzolan. Waste glass is cementitious in nature when it is finely ground, and especially when it is ground in a wet environment. The obtained waste glass slurries with finest particle size up to 10 μm show pozzolanic characteristics. The ASR tests results indicate that the presence of finely ground waste glass in a wet environment has a relatively small influence on ASR expansion.