Influence of Agricultural Waste as a Partial Substitute for Cement in Flowing Concrete for a Sustainable Environment

Large quantities of corn cobs, rice husks, and sugarcane bagasse are often burned or left to decay, contributing to air pollution and greenhouse gas emissions in many rural areas of Indonesia. However, earlier studies indicated that the ashes from these agricultural wastes have the potential to serve as partial substitutes for cement in concrete production, reducing environmental pollution. Because of their rich silica composition, the pozzolanic properties of corn cob ash (CCA), rice husk ash (RHA), and sugarcane bagasse ash (SBA) can improve the long-term performance of concrete. This research investigated the use of rice husk ash, sugarcane bagasse ash, and corn cob ash as alternative materials for partially replacing cement, focusing on their effects on the flowing concrete with the addition of Sika-Viscocrete as a superplasticizer. This study examined the properties of flowing concrete, including unit weight, compressive strength, and the efficiency of cement utilization. The unit weight of concrete was tested following SNI 1973:2008, while its compressive strength was evaluated in accordance with SNI 1974:2011. This study applied statistical analysis and linear regression. Experimental findings showed that the measured unit weight values were consistently within the interval of 2300-2500 kg.m^-3 and, according to the measured unit weight, the concrete was considered normal-weight concrete. The highest compressive strength obtained was 35.22 MPa at 7% variation of corn cob ash, and the highest efficiency in cement utilization was observed in flowing concrete with corn cob ash substitution. This is because among the alternatives, corn cob ash achieved the greatest strength improvement per unit of cement at 1.13 MPa per kg.m^-3. Statistical analysis revealed the effect of substitution levels, and the regression analysis yielded several data-based equations. Employing agricultural waste ash as a partial cement substitute provides a sustainable pathway toward reducing overall cement consumption.