For the last decade, recycled construction wastes were promoted to be reused in concrete manufacture process to achieve sustainability of structures. Recently, crushed glass has been investigated many researchers [1-9] as a partially replacement for coarse and fine aggregates, finally; cement. This study investigated the influence of both the mechanical behaviour and microstructure of cement mortar when partially replaced by powder glass. Here in, six mixes were design for six percentages of replacement; considered incrementally, each 5% (0%, 5%, 10%, 15%, 20%, and 25%) of cement weight. 36 mortar cubes and 18 prisms were cast and cured for 28 days. Then after, the specimens were tested in compression and indirect splitting tensile strength to determine their influence on mechanical properties. In addition, scanning electron microscope as well X-ray diffraction was used to examine their microstructure cement. The results showed that 20.5% increase in compressive strength at 7 days while at 28 days, the compressive strength increases insignificantly by value of 0.3% when using 5% GLP replacement. In addition, 46.9% increase was achieved in flexural strength at 28 days. Furthermore, the SEM micrographs observed some clear glass particles while the XRD clearly monitored the high count of silica and could not detect the calcium silicate that represents the amorphous part
