Strength Performance of Concrete Produced with Rice Husk Ash as Partial Replacement of Cement

Concrete is the most common construction material with its major constituent being cement. The production of this Cement results in a lot of environmental issues which include the constant emission of CO2 gas. Reduction of this gas, preservation of natural resources needed in the production of the constituent of cement and subsequent sustainability of concrete structures have fueled the search for alternative cementing material to produce environment-friendly construction materials. Recently, supplementary cementitious materials like the agricultural by-products are used to replace a portion of the cement in concrete mixtures. The use of such CSM in concrete not only prevents these products from being land-filled which causes pollution but also enhances the properties of concrete in the fresh and hardened states. These supplementary cementitious materials with pozzolanic action react with hydration products in cement to form calcium silicate hydrate (CSH) thus enhancing and improving concrete quality and consequently reducing the cost of concrete production. One of such material is Rice Husk Ash (RHA). The study investigated the chemical composition of RHA as well as the specific gravity, workability, compressive strength, split tensile strength and flexural strength properties, with varying percentage of blended cement concrete and 100% cement concrete of mix ratio 1:2:4 and water-cement ratio of 0.5 were examined and compared. Slump test and compacting factor test was carried out to check the effect of RHA on the workability of fresh concrete. RHA partially replace cement in the order of 0%, 5%, 10%, 15%, 20%, 25% and 30% were cast. The concrete specimens were tested at the ages of 7, 14, 21 and 28 days. The optimal cement replacement was found to be at 10% RHA. This combination gave a compressive strength of 26.8 N/mm2. This is close to the control concrete with compressive strength of 26.9 N/mm2 at 28days hydration period. Therefore, rice husk ash can be used as a replacement for cement in concrete