Many researchers are trying to optimize SCC mixture proportions using new materials. Using high content of Portland cement to produce SCC is one of the major challenges. This high content of cement causes higher cost of production. Also higher content of CO2 emission during the production of Portland cement into atmosphere, is one of environmental concerns. In this research, two approaches were adopted to lower the Portland cement: river sand with high content of fine particles and zeolite as the supplementary cementitious materials(SCM) were used. Portland cement was replaced by natural zeolite with the replacement levels of 5,10 and 15 percent in 0.42 and 0.46 of water to cementitious materials ratio. To investigate the rheology of SCC mixtures, slump flow, visual stability index, J-ring, T50, L-box and V-funnel tests were employed. Mechanical properties of hardened concrete were examined in 7, 28 and 90 days of curing, using compressive and flexural bending(third-point loading) experiments. Result of fresh concrete tests indicated that using zeolite improved the static stability and segregation resistance of concrete mixtures but increased the required dosage of high-range water-reducer agent(HRWRA). It was observed that , at the age of 7 days, natural zeolite caused compressive and flexural strength reduction; but at 28 and 90 days of curing, significant improvements were observed. Also in lower water to cementitious ratio replacement, zeolite had better impact on both rheological and mechanical properties.