Concrete mixture using natural coarse aggregate (A case study: Ongkak River– Dumoga)

In current construction, there are still areas that utilize natural materials such as aggregates from rivers as construction materials, one of which is in the Dumoga, Bolaang Mongondow, North Sulawesi. The communities in this area still use natural aggregates from the river in the concrete mixture in the development process. The purpose of this study was to provide information to the public about the material characteristics and quality of concrete using coarse and fine aggregates from the Ongkak River, Dumoga. Therefore, this research aims to compare the results of concrete compressive strength of several mixtures in the field (1: 1.5: 2.5) (1: 2 : 3) (1 : 2.5: 3.5) (1 : 3 : 3) and (1 : 3: 4). Based on the results of the compressive strength, the optimal compressive strength value on average at 28 days is in the specimens with mixed variations (1: 1.5: 2.5) is 24.178 MPa, followed by mix (1: 2.5: 3,5) of 17.094 MPa, mixture (1: 2 : 3) of 15.459 MPa, mix (1 : 3: 4) of 13.737 MPa, and mix (1 : 3 : 3) of 12.250 MPa respectively.