Evaluation of Corn Cob Ash as Mineral Filler in Asphalt Mixture

Integrating waste materials in the highway sector, especially in asphaltic concrete mixture offers ecological and economic benefits. This study examines the effects of using corncob ash (CCA) as a replacement for the traditional stone dust filler in 5%, 10%, 15%, 20%, and 25%. Volumetric parameters including flow test, bulk density, air void, stability, and voids in mineral for obtained mix asphalt were determined. The optimum bitumen content (OBC) was determined using six replacement rates of 5.0 to 7.5% at intervals of 0.5% by weight. In addition, it was observed that 15% CCA filler replacement produced the best results for OBC at 6.3%, maximum stability at 14.4 KN, flow at 3.8 mm, void filled with bitumen (VFB) at 84.9%, bulk density at 2.55 g/cm³, air void at 4.3%, and finally marshall quotient value at 3.8 KN/mm, which satisfied all requirements of the standard specification for medium traffic roads in asphalt mixture. The study’s results also demonstrated that some of the stone dust fillers in hot mix asphalt may be effectively replaced by agricultural waste materials, potentially enabling the reuse of agricultural waste, optimizing construction costs, and reducing nuisance waste.