Performance evaluation of asphaltic concrete incorporating milled egg-shell ash (mesa) as bitumen strength modifier and filler

Abstract

Pursuant to the quest for sustainable and cheap pavement construction materials which have the potential of spurring the development of roads with low construction costs; and with the worrisome increase in the amount of eggshell wastes resulting from large consumption of poultry birds, this research assessed the engineering properties of bitumen modified with Milled Egg Shell Ash (MESA) and subsequently the performance of asphalt concrete with MESA as partial substitute for filler. Physicochemical characterization was carried out on the virgin bitumen and the MESA. Milled proportions of the egg shell ash was blended with bitumen at 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, followed by a complete substitution at 100%, by weight of mineral aggregates; and thereafter incorporated as filler using the same proportions. The penetrometer and rotational viscometer were engaged to determine the penetration and viscosity of the modified bitumen, and the Marshall mix design method was subsequently employed to determine the stability and flow of the asphaltic concrete composite. The modification of bitumen with egg shell ash resulted in a decrease in penetration of bitumen from 80/100 pen to 60/70 pen, as well as rotational viscosity met the required standard. Marshall stability decreased gradually with increased MESA content. Given the expected standard value of Marshall stability for wearing courses to be not less than 7.5 kN, the stability value of 31 kN obtained at 10% MESA, was recommended for sustainable pavement works. The X-ray Florescence (XRF) result showed a high presence of Calcium in terms of intensity and content in the Hot Mix Asphalt (HMA) modified with MESA, while the scanning electron microscope (SEM) provided a clear perspective of the interaction between the mineral aggregates, MESA, and bitumen in the entire HMA mixture. The results have shown feasible use of MESA as partial aggregate substitution in HMA which is recommended for light weight pavements or medium trafficked roads such as in found parking lots, walk ways, office complexes, university environments and short accesses.