Influence of Coarse Aggregate Type And Mixing Method On Properties Of Concrete Made From Natural Aggregates In Ogbomoso Oyo State Nigeria

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Author(s) Ajamu S.O. | Ige J.A.
Pages 426-433
Volume 5
Issue 7
Date July, 2015
Keywords Mixing Method, Aggregate Type, Compressive Strength, Compacting Factor

Abstract

There have been several reported cases of building collapse in Nigeria as well as other countries of the world in the recent times. So many of these building failures have been attributed to various factors ranging from poor design, poor detailing, poor construction materials employed during their construction, poor supervision. The most predominant factors attributed to many of these structural failures have been the poor construction materials used. However, deviation from standard procedures or poorly mixed concrete constituents exacerbates the quality of concrete produced and this often result in poor performance of concrete structures, and as a result of this, progressive or sudden collapse of the structures may result. Therefore this study is conducted to examine the potential impact of coarse aggregate type and mixing procedures on the properties of concrete produced.In this study, gravel and crushed granite were used and three mixing methods were also used such as mixing on bare ground, on concrete platform, and the use of mixing machine. Sieve analysis of the fine and coarse aggregates used, the compaction factor test on fresh concrete produced were carried out using standard procedures; the mix ratio used was 1:3:6 with water-cement ratio of 0.65. The compressive strength tests of samples of concrete produced from different mix methods were carried out in accordance with procedures outlined in BS 882 and BS1881 using compression testing machine (Controls Milano-Italy, range: 0 – 1500 kN). The results of the sieve analysis of the aggregates showed that both fine and coarse aggregates used are poorly graded by the Unified Soil Classification System (USCS) standard. For the granite concrete, the compaction factor for mixing on concrete platform and using mixing machine is 0.93 while that of concrete mixed on bare ground is 0.91. The corresponding result for gravel concrete 0.94, 0.92; The compressive strength at 28 days of concrete made with granite on bare ground is 26.49 N/mm2, that of concrete mixed on Concrete Platform is 29.33 N/mm2 and for mixing machine is 29.60 N/mm2. The corresponding values for gravel concrete are 10.13 N/mm2, 13.56 N/mm2 and 15.11 N/mm2.To achieve a high compressive strength, density and workability of concrete mix, machine mixing method should be used for the mixing of concrete, and granite material should always be used for the concrete production.

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