USE OF KUTA GRAVEL AS COARSE AGGREGATE FOR SUSTAINABLE CONCRETE PRODUCTION

Abstract

Abstract Continuous rise in the world’s population has resulted in increase in the demand for shelter and consequently, higher demand for concrete. By occupying three-quarter of concrete volume, the demand for aggregates has also increased. Processes involved in the manufacture of the commonly used crushed aggregates are major sources of environmental pollution. There is need therefore, to find alternative sources of aggregates to cater for the high demand and also solve the problem of environmental pollution. This study investigated the properties of coarse aggregate obtained from Kuta all-in aggregate and its compressive strength when used in producing concrete. The coarse aggregate was separated from the all-in aggregate using 4.75mm BS standard sieve. Properties of the coarse aggregate (mechanical and physical) were determined in accordance with relevant parts of BS 812. Five concrete mixes were made with varying values of Water/Cement (W/C), Coarse Aggregate/Total Aggregate (CA/TA) and Total Aggregate/Cement (TA/C) ratios. Three (3) 150×150×150mm concrete cubes were cast for each mix and checked for compressive strength at 28 days. The properties of Kua gravel determined showed that it has a specific gravity value of 2.60, water absorption value of 0.60%, flakiness index of 26%, elongation index of 29%, AIV of 16.45%, ACV of 25.82%, percentage air void (uncompacted) of 41.5%, uncompacted and compacted bulk densi- ties of 1523.47kg/m3 and 1640.52kg/m3 respectively. The particle distribution falls within the limit for graded aggregates between 20mm-5mm.The properties of Kuta gravel so determined, fall within the acceptable limits for properties of natural coarse aggregates used in producing concrete. Concrete mix with a combination of W/C=0.4, CA/TA=0.55, TA/C=3 yielded the maximum compressive strength of 26.8N/mm2. It was concluded that Kuta gravel is suitable for use as coarse aggregate in producing structural concrete requiring a strength of 25N/mm2 or less.