Production of Concrete Using Rubber Wood Bottom Ash as a Replacement for Fine Aggregate

Abstract

This research aims to investigate the optimal ratio for using rubberwood bottom ash as a replacement for fine aggregate in concrete production. The study replaced fine aggregate with bottom ash at 0%, 10%, 20%, 30%, 40%, and 50% by weight. The compressive strength was determined for concrete shape into cubes of 15x15x15 cm and prisms of 7.5x7.5x28.5 cm, with design compressive strengths of 240 and 320 kg/cm². The results indicated that the compressive strength of the concrete decreased as the replacement ratio of fine aggregate with bottom ash increased. For the 240 kg/cm² design compressive strength concrete, all replacement ratios met the required compressive strength criteria. However, for the 320 kg/cm² design compressive strength concrete, only the concrete with 0%, 10%, 20%, and 30% replacement ratios met the criteria. The study showed that the density of concrete decreased as the proportion of bottom ash increased. Regarding dry shrinkage, the 320 kg/cm² concrete exhibited lower dry shrinkage compared to the 240 kg/cm² concrete due to its lower water-to-binder ratio, which reduced the amount of water in the mix and hindered evaporation. The water absorption results indicated that both the 240 kg/cm² and 320 kg/cm² concrete had low absorption rates, with the 240 kg/cm² concrete showing slightly higher absorption than the 320 kg/cm² concrete. However, the water absorption values for both types were within acceptable standards, making them suitable for structural applications. In conclusion, the results indicate that rubberwood bottom ash can be used as a substitute for fine aggregate in concrete production. Concrete with a design compressive strength of 240 kg/cm² can accommodate up to 50% replacement by weight, while concrete with a design compressive strength of 320 kg/cm² can accommodate up to 30% replacement by weight.