The concept of using milled waste glass as partial replacement for cement in cement paste and mortar was investigated to reduce the adverse environmental and energy impacts of cement and cement-based products. Based on the experimental investigations it was found that waste glass, when milled to micro-scale particle size, undergoes pozzolanic reaction with cement hydrates. These reactions bring about favourable changes in the structure, including pore system characteristics of the hydrated cement paste and mortar. Use of milled waste glass, as partial replacement of cement, produced significant gains in the resistance to moisture sorption, chemical stability and improvement in microstructure of the cementitious materials. Milled waste glass was also found to suppress alkali–silica reactions. Unlike normal pozzolanic reactions, those involving glass do not reduce the alkalinity of cement paste; this is favourable to the chemical stability of cement-based materials and the protection of reinforcing steel against corrosion in concrete.alues derived using available design codes.