Every year, millions of tons of waste glass are generated all over the world and disposed in landfills. Utilization of this waste by substituting a certain share of cement in cement mortars can contribute to the reduction of environmental pollution in two aspects: the utilization of waste and the reduction of the cement content in cement-based mortars. The cement industry is responsible for approximately 6% of global CO₂ emissions. Seven different mortar mixes, containing between 0% and 30% of waste glass powder added by weight of cement, were analyzed. The following physical and mechanical properties of the mortar mixes were measured: compressive strength, flexural strength, and density. The test results revealed that waste glass powder can be used in small amounts in cement-based mortars to reduce the amount of cement and to utilize waste glass. A higher performance, modified cement-based mortar can be produced for civil engineering applications by replacing 5% with waste glass powder. The linear regression equations obtained illustrate the relationships between the density and compressive strength, and between density and flexural strength at 28 days.