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Concrete is the most widely used construction material in the world. In concrete 60-75% by volume is aggregate. Out of this volume, 30-40% is constituted by sand. Sand is used more than any other natural resources except water and air, However, it’s extracted at a rate far greater than it’s renewal. The availability of sand in the growing demand of the Ethiopian construction industry will be a challenge due to a wide range of variability, cost and, quality problems. Keeping this in mind, the aim of this study is to investigate the workability, strength, and cost of normal strength concrete by partially replacing sand with marble waste and scoria. Experimental investigations were conducted to study the chemical, physical and mechanical property of concrete containing marble waste and scoria. There are 10 different sets of mixes including the control mix used for investigations with constant water-cement ratio of 0.49 and slump range between 75100 mm for concrete having a compressive strength of 25 MPa. Marble: Scoria ratio of 2:1, 1:1 and 1:2 were used and then the combined level of both marble waste and scoria increase from 33 to 67 to 100%. A total of 90 (150mm×150mm×150mm) concrete cubes were cast and tested. The workability of each fresh concrete mix was checked immediately following the mixing. Compressive strength tests were carried out at 3, 7 and 28 days. The chemical analysis test result shows that marble waste is mainly composed of Calcium Oxide (CaO) and Silicon Oxide (SiO2), whereas scoria is composed of Silicon Oxide (SiO2), Aluminum Oxide (Al2O3), Iron Oxide (Fe2O3), Calcium Oxide (CaO) and Magnesium Oxide (MgO). Concrete containing marble waste and scoria as sand replacement shows a better compressive strength than the conventional concrete but the workability and compressive strength decreased with an increase in percentage replacement of marble waste and scoria. Concrete containing marble waste and scoria can save up to 4.5% of the total cost of concrete and the optimum replacement rate is 22.5% marble waste and 44.5% scoria. |
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