MECHANICAL PERFORMANCE ENHANCEMENT OF ASPHALTIC CONCRETE USING SORGHUM HUSK ASH AND CORN COB ASH AS SUSTAINABLE FILLERS

Abstract

This study investigated the performance strength characteristics of asphaltic concrete modified with Sorghum Husk Ash (SHA) and Corn Cob Ash (CCA) as partial filler replacements. The primary aim is to enhance asphalt performance while promoting sustainable waste management through the utilization of agricultural by-products. A series of asphaltic concrete samples were prepared by replacing conventional mineral filler with varying proportions (10%, 20%, 30%, and 40%) of SHA–CCA blends at 10% intervals, ranging from 100% CCA to 100% SHA. The modified samples were evaluated based on Marshall Stability, flow, and Marshall Quotient in accordance with Federal Ministry of Works (FMW, 2016) and Asphalt Institute (AI, 1991) standards.Results revealed that ash incorporation improved asphaltic concrete properties at moderate replacement levels. The highest Marshall Stability of 21.8 kN was observed at 30% ash replacement with a 40:60 SHA–CCA ratio, while optimal flow values (2.5–3.6 mm) and Marshall Quotient values (up to 7.2 kN/mm) were recorded at 20% replacement with 60:40 SHA–CCA mix. Generally, performance improved with blended ash inclusion up to a peak point, beyond which further SHA increase led to a reduction in strength. All mixes met FMW standards for stability and flow, although AI standards for flow were not satisfied due to methodological differences.The study concludes that SHA and CCA are effective, environmentally friendly alternatives to conventional fillers, with 20–30% replacement levels offering the best balance of strength and durability. The findings support the adoption of agro-waste fillers in sustainable pavement construction.

Keywords: Asphaltic Concrete; Sorghum Husk Ash (SHA); Corn Cob Ash (CCA); Marshall Properties; Sustainable Pavement Materials