Experimental Studies on the Use of Local Grinded Aggregate in Enhancing Stability, Reduction of Flow, Air-voids and Deformation of Modified Asphalt Concrete for Medium Collector Roads

Abstract

The adverse environmental impact of man-made and agricultural waste/by-products combined with the rising cost and difficulty in obtaining construction materials have influenced research into better ways to manage these wastes/by-products by incorporating them in asphalt concrete mix design. Different researches have shown that some agricultural waste/by-products can be included as mineral fillers in hot-mix asphalt concrete to obtain certain desirable properties. It is on this basis that this research attempts to investigate the effect of Periwinkle Shell Ash(PSA) on the mechanical properties of asphalt concrete, which will serve as basis for the use of such materials in pavement construction. An experimental approach was adopted to achieve this goal using the Marshal Mix design method representative examples. Stability and flow were obtained using the Marshal apparatus, while the Asphalt Institute Model was used to obtain the dynamic modulus of the samples for both un-soaked and soaked conditions. The results show that the mechanical properties, such as stability, density, flow and air voids obtained from the modified HMA concrete was better than that of the conventional (unmodified) HMA concrete due to the addition of Periwinkle Shell Ash. However, 2.5% PSA content by weight of aggregates is the threshold content to attain maximum values of stability and tensile strength. The Elastic properties such as Dynamic Modulus E* (which relates to the stiffness of the HMA concrete), Elastic modulus, and Poisson’s ratio obtained from the modified HMA concrete significantly improved upon addition of PSA. However, while the dynamic modulus increases linearly with increasing PSA content, the filler must not exceed 2.5% by weight of aggregates at in order to achieve maximum elastic modulus.

Keywords: Local grinded-aggregate (as PSA), Asphalt Concrete, Stability, flow, Air-voids Compressive Strain, , Tensile Strength (Deformation)