EVALUATING THE MECHANICAL PERFORMANCE OF SORGHUM STALK ASH AND SORGHUM HUSK ASH AS A SUSTAINABLE MINERAL FILLER IN WARM MIX ASPHALTIC CONCRETE

Abstract

The performance of road construction materials has prompted research into alternative fillers. Concerns about the need to mitigate depletion of natural resources and environmental degradation became a dire need. The high production temperature of Hot Mix Asphalt (HMA) which results in significant energy consumption, greenhouse gas emissions, and occupational health risk has driven research into alternative Warm Mix Asphalt (WMA) technologies. Thus, this study investigated the mechanical performance of WMA incorporating Sorghum Stalk Ash (SSA) and Sorghum Husk Ash (SHA) as sustainable fillers. The study adopted bitumen of 60/70 penetration grade. Sasobit proportion of 3.5 wt. % of the bitumen was adopted, which serves as an additive to produce WMA samples. Aggregates and filler were added to unmodified and modified WMA concrete samples. The samples were produced by incorporating SSA and SHA at a proportion of 0 – 100 wt. % at 10% intervals. Marshall Stability and Flow (MSF), Indirect Tensile Strength (ITS) and Tensile Strength Ratio (TSR) properties of the WMA samples were evaluated. The optimum replacement level was found at 40 wt.% (SSA and SHA) for the MSF resulting in 18.85 kN and 4.30 mm, respectively, exceeding the minimum of 8 kN and 4 mm, respectively. Furthermore, ITS and TSR recorded 40 wt.% replacement resulting in 250 kN/m² and 82.7%, respectively, exceeding the minimum recommended TSR of 80%. This study is limited to mechanical performance without considering the Microstructural analysis of the concrete. These finding revealed that incorporating SSA and SHA enhance pavement construction properties and promote sustainability.