Increase the amount of gases emission and construction materials waste was lead to increased interest to used recycled materials in building projects. In this research the effect and interaction of used recycle cement mortar as aggregate to replaced natural aggregate (sand) on cement mortar properties with variable curing time and constant water to cement ratio (W/C = 0.5) used is studied. Four group of cement mortar were produced (M0, M25, M50, M100) with different recycled aggregate weight percentage (0, 25, 50, and 100). The compressive strength, density, water absorption and porosity percentage were tested. The results shows the compressive strength and density were decreased with recycle aggregate percentage increment in cement mortar composition, while, the water absorption and porosity percentage increased with recycle aggregate percentage increment in cement mortar ,. The lower compressive strength and density obtained in M100 samples were 26.08 MPa, 1.83 g/cm 3 , while; the higher compressive strength and density obtained in M0 samples were 32.95 MPa, 2.28 g/cm 3 , respectively. the higher water absorption and porosity percentage obtained in M100 samples were 12.05, 18.08, while; the lower water absorption and porosity percentage obtained in M0 samples were 7.86, 15.25, respectively.

This study involves natural--materials replacement and its reaction with cement mortar behavior for many mortar samples under variable curing time with constant water to cement ratio (W/C = 0.5).In this researchsomeproperties such as (compressive strength the surface hardness and water absorption test), were affected by adding small ratios ofpowder (from (RHA) and (BRP) particles)as replacements to the Ordinary Portland Cement (OPC) / type (I). The percentages of natural materials additives replacement on the mixture of mortar include (0, 5, 10, 15 and 20%) with constant (W/C) ratio. Also the amount of the fine aggregate used was three times the amount of cement. The results showed that, the compressive strength and splitting tensile strength and water absorption of the mortars for (replacement) gives better properties than mortar without replacement in all tests. Best enhancements in properties for mortars with pozzalanic replacements were achieved at (15%) for (RHA) and 10% for (RBP) replacement from weight of cement.