Abstract:
Construction materials in construction activity focuses on improving the quality, cost, ease of using materials in different form, increasing performance and so on. But if improving cost is considered, quality should not be compromised. The practice of using alternative ingredients to produce materials is weak in Ethiopia. Compressive strength is one of the important mechanical properties of concrete, and the indicator of compressive strength of manufactured sand concrete is more important to be promoted. This paper presents the results of the compressive and flexural strength tests on concrete specimens using the manufactured sand, the replacement ratios of manufactured sand by volume to the natural sand are [0 %, 20 %, 40 %, 60 %, 80 %, and 100 %] respectively. The optimum replacement ratio of manufactured sand by volume to the natural sand concrete is suggested. This could be used as a reference for the applications of the concrete using the manufactured sand in engineering. Initially, different natural and manufactured sand samples to be used in the concrete mixes were collected and their physical properties were studied. Six different concrete mixes having one mix proportions for both natural and manufactured sand [i.e.0%MS+100%NS, 20MS%+80%NS, 40%MS+60%NS, 60%MS+40%NS, 80 %MS+20%NS, and 100 %MS+0%NS] were prepared for normal concrete strength. The properties of these mixes have then been assessed both at the fresh and hardened state. In addition, comparison of costs for each concrete mixes based on the price of the concrete material collected from Debre Markos towns were made. According to the results, the maximum mean compressive and flexural strength was 35.13Mpa and 3.86Mpa respectively in natural sand replacement with manufactured sand [60 %MS+40%NS], and the corresponding optimum production cost of concrete per unit volume was found at [60%MS+40%NS] combinations 1929.73Birr/m 3 .
