ABSTRACT
Due to the need for the construction of new infrastructures like roads and buildings, which have basically been produced with Portland cement, it becomes pertinent that other materials that can impact the strength of the concrete be sourced. The use of rice husk ash (RHA) as an additive has been employed by many researchers, but the need to study the use of RHA and other pozzolanic materials becomes important. In this research, RHA and SDA were mixed with cement in various proportions to produce concretes having 28-day target strength of 30MPa. The blend of the cement with RHA and SDA were 100%, 0, 0 which is termed CRS01, 80%, 15%, 5%, which is termed CRS02, 80%, 10%, 10% which is also termed CRS03, 80%, 5%, 15% which was termed CRS04 and 80%, 0, 20% which was termed CRS05. The concrete cubes prepared were cured for 3, 7, 28, 56 and 90 days. After that, various tests including compressive strength, water absorption and sorptivity tests were conducted on the concrete samples. The addition of RHA and SDA to cement increased consistency due to their high-water affinity from silicon dioxide content. The concrete with partial cement replacement (5% RHA and 15% SDA) had lower density, indicating lightweight concrete, while the maximum density was achieved at this composition. Although the compressive strength of concrete with RHA and SDA was slightly less than cement-only concrete, it still exceeded the target strength of 30 N/mm² after 28 days of curing. Water absorption tests showed over 7% absorption, indicating the concrete with RHA and SDA was of ordinary quality, whereas 100% cement concrete exhibited better quality. Additionally, sorptivity, or water capillary rise, was higher in RHA and SDA concrete compared to cement-only, indicating increased water penetration.
