STUDY OF COMPRESSIVE STRENGTH OF CONCRETE MODIFIED WITH BUKHO STONE FRACTIONS

Innovation in concrete materials persists, offering alternatives in situations where the primary material becomes scarce. Alternative materials need to be considered for quality and availability at the location of the construction work. The bukho stone material is easily available on one of the islands in Indonesia, whereas the main material for concrete is very limited. This study used bukho stone fractions as a partial replacement material for sand and partly for gravel. The amount of mixture used was 5%, 10%, and 15%, respectively. The concrete constituent materials were mixed in such a way as to mold cubical specimens measuring 15 cm x 15 cm x 15 cm. Concrete compressive strength tests were conducted at 7 days, 14 days, and 28 days of concrete age. The results showed that the potential of bukho stone fractions with a size < 4.75 mm as a partial replacement of sand provided significant compressive strength values at the maximum use of 10% bukho stone. Fragments of bukho stone with a size > 4.75 mm as a partial replacement of gravel showed an increasing trend in compressive strength for the use of more than 10% bukho stone. Longer concrete ages showed an increase in compressive strength in each of the concrete mixtures used, this could be due to the pozzolanic reaction in the mixture continuing to occur at longer concrete ages.