In the present work, the properties of rubberize cement mortar are treated with alkaline materials and tested and compared with normal rubberize and normal cement mortar. The rubber, which is treated with different alkaline materials such as: (NaOH, NaOCL, and Commercial detergent powder) of high pH (13-14), is used as partial replacement for sand in cement mortar. The percent of replacement ranged from 15 to 35%. Compressive strength, flexural strength, and modulus of elasticity are also tested for rubberize cement mortar, rubberize cement mortar treated with alkaline materials, and normal cement mortar. The results show that the treatment of rubber with alkaline materials significantly improves the properties of cement mortar. Moreover the results also show that NaOCL gives better improvement more than NaOH, while commercial detergent powder shows negative effects on all cement mortar properties.