Because of high constructional activities, use of concrete is very extensive and its ingredients, i.e. cement, sand and gravel becomes scarce. Many studies were carried out by researches for partial or optimal replacement of cement, sand and gravel by alternate materials. Cement production leads to global warming as CO2 is released in atmosphere during its production, equal to seven percent of total CO2 emission in world. Therefore cement is partially replaced by rice husk ash (RHA) as it is rich in silica. Large space in concrete (35%) is filled by sand. Natural sand may get exhausted in future because of its high demand. Digging of sand in huge quantity nearby rivers is hazardous to environment as it effects ground water level and causes soil erosion. Therefore natural sand is partially replaced by manufactured sand (MS) as MS is obtained on crushing of granite rocks which are easily available at nearby places. Use of MS reduces the transportation cost of carrying natural sand from far-off river beds. In the current study, cement is partially replaced by RHA by 10% and sand by MS by 25%, 50%, 75% and 100% to get desired strength concrete. Various tests like compressive strength, split tensile strength and flexural strength were conducted on specimens. Present study revealed that to get M20 concrete, 100% sand replacement with MS is the optimum proportion for 10% replacement of cement with RHA. © 2019, Blue Eyes Intelligence Engineering and Sciences Publication. All rights reserved.