Appraisal of Different Production Methods on Coarse Aggregate Performance in Concrete

Properties of concrete have been reported to depend mainly on cement and coarse aggregates. Coarse aggregates, in turn, depend on the type of the parent rock from which aggregates has been obtained as well as the methods of aggregates production. Suitability of coarse aggregates obtained from three different methods of production namely; machined crushed stone from the quarry (MCSQ), manually crushed stone by application of fire (MCSF) and manually crushed stone with hammer after blasting (MCSH) was investigated. A total number of 216 concrete cubes were cast, in order to determine the compressive strength of the various concrete made with MCSQ, MCSF and MCSH; with varied mix ratios of 1: 1½: 3, 1: 2: 4 and 1: 3: 6. The results of aggregate crushing value (ACV) and aggregate impact value (AIV) for MCSH are 28.4 % and 15.06 % respectively, for MCSF are 30.7 % and 19.5 % respectively, and for MCSQ are 29.8 % and 18.07 % respectively. Furthermore, the compressive strength of concrete cubes obtained from MCSQ, MCSF and MCSH respectively at the end of 28 days were: 22.07 N/mm2, 19.04 N/mm2 and 28.15 N/mm2 respectively for the mix 1: 11/2: 3; 22.00 N/mm2, 20.96 N/mm2 and 23.33 N/mm2 respectively for the mix 1: 2: 4 and 17.04 N/mm2, 12.52 N/mm2 and 17.48 N/mm2 respectively for the mix 1: 3: 6. . The compressive strength values obtained for the various mixes and aggregates fall within 15 to 30 N/mm2 as specified in BS EN 1992-1-1:2004 except the concrete obtained from MCSF for the mix 1:3:6 at 28 days curing. The statistical analysis was done and reported for the various results.