Physico-Chemical Characterization of the Constituent Materials for Sustainable Concrete: Incorporating Rice Husk Ash and Corn Cob Ash as Partial Cement Replacements

Abstract

This study evaluated the physico-chemical properties of constituent materials for sustainable ternary blended concrete incorporating rice husk ash (RHA) and corn cob ash (CCA) as partial cement replacements. The objective was to assess the suitability of these agricultural by-products as supplementary cementitious materials (SCMs) for sustainable concrete production. Experimental investigations were conducted on the constituent materials, RHA, and CCA following British Standards (BS EN) and ASTM procedures to ensure reliable and accurate results. X-ray fluorescence (XRF) analysis showed that the combined SiO₂, Al₂O₃, and Fe₂O₃ contents were 79.55% for RHA and 63.45% for CCA. Based on ASTM C618:2019, RHA was classified as a Class F pozzolan, while CCA was classified as a Class C pozzolan, confirming their suitability as SCMs. Physical characterization demonstrated compliance with standard requirements, including a cement consistency of 31%. The cement paste exhibited an initial setting time of 2 h 5 min and a final setting time of 3 h 39 min. Aggregate tests, including specific gravity and particle size grading, also satisfied relevant standards for quality concrete production. X-ray diffraction (XRD) and scanning electron microscopy (SEM) identified amorphous silica and other reactive phases in both ashes, confirming their pozzolanic potential and ability to participate in cement hydration, thereby enhancing concrete strength and durability. Overall, the findings demonstrate that RHA and CCA are viable supplementary cementitious materials capable of reducing cement consumption, lowering carbon emissions, and promoting environmentally sustainable concrete production without compromising material quality in practical construction applications and long-term infrastructure development across settings.