With the rapid development of construction and the construction industry, the demand for mortar as a building material is also increasing. With the development of economic society, glass products have been widely used, and glass manufacturing enterprises have produced hundreds of tons of glass fragments and slag. The main component of glass is silica, which has the potential to be used as an auxiliary cementing material. Therefore, waste glass is expected to be recycled in buildings to achieve sustainability. However, due to the chemical properties of the silica tetrahedral structure stabilized by the waste glass, its pozzolanic activity is potent and needs to be stimulated. Glass powders with different degrees of fineness were obtained by physical grinding of waste glass powder (WGP). The standard consistency water consumption, compressive strength, and flexural strength of waste glass powder cement mortar were studied. The grinding times of waste glass powder are 5 min, 10 min, and 15 min, respectively, and the dosages are 5%, 10%, 15%, and 20%, respectively. The experimental results show that the average particle sizes of the grinding times of 5 min, 10 min, and 15 min are 1670.0 μm, 243.0 μm, and 13.2 μm, respectively. The waste glass powder with a grinding time of 15 min has a specific surface area of 670 m2/kg, which has high pozzolanic activity. The compressive and flexural strength of cement mortar specimens with 5% waste glass powder is the best, and the later strength is improved to a certain extent. The consistency of the cement mortar increased after adding waste glass powder. Compared with the 28 d compressive strength activity index of pure cement mortar specimens, the waste glass powder with 5–10% content reached more than 70%.
