EFFECTS OF COARSE AGGREGATES GRADINGS ON THE PROPERTIES OF CONCRETE

Abstract

Coarse aggregates gradings have varying effects on the properties of concrete. Coarse aggregates of sizes 10mm, 20mm and 25mm were used for this study. Sieve analysis was conducted on these aggregates. Their coefficients of curvature (Cc) ranged between 1.01 and 1.19, while the coefficients of uniformity (Cu) ranged between 1.24 and 1.73, showing that they are all uniformly graded. 10mm and 25mm coarse aggregates were mixed in various proportions to produce five different concrete mixes (concrete C1, C2, C3, C4 and C5). Concrete C6 was produced with 100% 20mm and was used as a check. Slump test was performed for each mixture, C1 gave the highest slump height of 88mm. Compressive strengths of the cast concrete cubes were determined after 7- and 28-days curing periods. C4 gave maximum compressive strength of 26.33N/mm2 at 28 days. Increase in the percentages of 25mm aggregates resulted in higher compressive strength and decreased workability.