The main objective of this research is to investigate some properties of fresh and hardened concrete using glass powder as a partial replacement of cement at percentages of 15%, 25%, and 35% by weight, and to determine the optimum replacement ratio. Four concrete mixes were prepared with replacement levels of 0% (control mix), 15%, 25%, and 35% of cement by glass powder. Six cube specimens were cast for each mix. Tests were conducted on fresh concrete (slump test) and hardened concrete (compressive strength test) at curing ages of 7 and 28 days. The results showed that the workability of concrete increased with increasing percentages of cement replacement by glass powder; however, the slump values remained lower than that of the control mix. Moreover, the results indicated that replacing 15% of cement with glass powder increased the compressive strength by 7% compared to the control mix (0%). Based on the results obtained, the optimum percentage for partial replacement of cement with glass powder is 15%.