Investigation of Coarse Aggregate Special Gradation on Concrete Strength

The development of concrete technology that increases over time and the number of concrete users in the field of construction make an effort to create a good and economical concrete quality. One attempt to increase the tensile strength of concrete is by using special gradations on coarse aggregates (gravel). Coarse aggregate (gravel) is a concrete material that has high strength and contributes the greatest volume in the concrete composition. This composition should be a coarse aggregate (gravel) capable of contributing optimally to the concrete. Gradation specifically in coarse aggregate (gravel) is a gradation with a certain size range so that the future of concrete can serve as a concrete intact and solid, in which the coarse aggregate (gravel) with grains smaller to fill the gap that exists between the coarse aggregate (gravel) with grain greater than. Based on the explanation above, this final project uses coarse aggregate (gravel) gradations. There are 3 kinds criteria of coarse aggregate (gravel) used divided into normal concrete, gradation A, and gradation B with comparison of concrete compressive strength test at 7 days, 14 days, 21 days and 28 days. The results of the study showed that the average maximum concrete compressive strength was 25,67 MPa which was found in gradation B with 28 days of concrete. This shows that with the many variations of coarse aggregate (gravel) gradations can fill a small gap in the concrete mixture compared to concrete which only has one variation of coarse aggregate (gravel) size.