Using Cube Coarse Aggregate to Determine the Compressive Strength of Concrete by Measuring Packing Density and Using Indian Standard and ACI Methods with Variations of Testing Age and Cement Products

One of the ingredients that make up concrete is coarse aggregate. The coarse aggregate used is generally in a non-uniform shape (a mixture of cubic, oval or flat, or neither oval nor flat). This research uses coarse aggregate in the form of cubes only and in the form of a mixture, with the aim of determining the compressive strength of concrete using the Indian standard mixture design method and the ACI method. The materials used are cement obtained on the market with various types of PPC, OPC and PCC, fine aggregate (from Muntilan, Yogya, Indonesia) and local coarse aggregate (from Jumantono, Karanganyar, Indonesia), specifically coarse aggregate in the form of cubes and mixtures. The shape of the test objects is cylindrical, and the testing age of the test objects is 7 and 14 days with a design concrete compressive strength of 35 MPa. The highest compressive strength results were obtained for the following type of cement variation: PPC = 14.21 MPa (7 days) and 16.62 MPa (14 days). The lowest compressive strength results for the PCC cement variation were 7.45 MPa (7 days) and 8.75 MPa (14 days). Meanwhile, the compressive strength value of concrete using the ACI method obtained the highest compressive strength results for the PPC cement variation of 20.11 MPa (7 days) and 33.74 (14 days), and the lowest concrete compressive strength for the PCC cement variation was 11.96 MPa (7 days) and 15.26 MPa (14 days). Also, from the research results, the highest packing density value obtained in the CA and FA mixture aggregate test was 0.751 g/cm3, in the proportion CA3/8″:CA3/16″:FA = 12%:28%:60%. It is known that the use of PPC cement can produce the highest compressive strength values compared to using PCC and OPC cement, which shows that even when the same form of coarse aggregate and the same design concrete quality are used, variations in cement can affect the high compressive strength of the concrete. The use of coarse aggregate in the form of cubes produces higher aggregate packing density and compressive strength of concrete compared to using coarse aggregate in mixed forms (cubes, flat and oval).