ABSTRACT
Concrete is a mixture of fine aggregate (sand), coarse aggregate (rock), cement, and water. The increasing demand of concrete for construction and development of infrastructure has drawn the attention of many researchers in searching for less expensive alternatives to the traditional materials employed in the construction industries in an attempt to reduce the high cost of construction. This paper features an experimental study on the replacement of sand with quarry dust and its influences on the properties of fresh and hardened concrete. The project is about replacing sand in concrete production with quarry dust at varying percentage (0%, 25%, 50%, 75% and 100%) to check if the strength matches that of grade MIS with a mix ratio of I :2:4 and also the proportion which has the highest strength. The test carried out includes particle size analysis, slump test, and compressive test. Sand was replaced with Quarry dust by weight at 0%, 25%, 50%, 75% and l 00%. The slump value obtained from the control mix of the washed sample was 110 mm while sand replaced by quarry dust at 25 %, 50%, 75%, and 100% were 87 mm, 78 mm, 55 mm and 48 mm respectively and also the slump value obtained from the contro.1 mix of the unwashed sample was 53 mm while sand replaced by quarry dust at 25 %, 50%, 75%, and I 00% were 80 mm, 72 mm, 35 mm and 83 mm respectively. The control mix of the washed at 28 days has a compressive strength of22.96 N/mm2 while the replaced mix at 25 %, 50%, 75%, and I 00% has 23.14 N/mm', 15 .84 N/mm2 , I 6.87 N/mm2 and 17.18 N/mm2 respectively and also The control mix of the unwashed at 28 days has a compressive strength of 16.21 N/mm' while the replaced mix at25 %, 50%, 75%, and 100% has 18.15 N/mm', 18.9N/mm 2 , l 9.47N/mm 2 and 22.03 N/mm2 respectively. This research concludes that at the 25% replacement of the washed sample, was found to give a higher strength than that of the control mix as it approaches 14, 28 and 60 days of curing. A partial replacement of 25% gives the highest compressive strength. And according to the result, it meets up with the target strength of the control mix (MIS). Concrete with washed fine aggregate has a higher compressive strength compared to that of concrete produced with unwashed fine aggregate. The variation in strength of concrete is as a result of the presence of silt in the unwashed material. The silts reduces the strength of concrete.
