Sustainability Assessment of the Engineering Properties of Asphalt Concrete Incorporating Pulverized Snail Shell Ash as Partial Replacement for Filler

Abstract

Abstract In furtherance to the search for reliable and cost-effective road construction materials which is expected to engender the development of sustainable and less expensive pavements, coupled with the increase in agricultural wastes due to the current rise in the consumption of white meat, this research investigated the engineering properties of modified bitumen and subsequent performance of asphaltic concrete incorporating Pulverized Snail Shell Ash (PSSA) as strength modifier and filler. In order to achieve specific objectives, preliminary physical and chemical tests were initialized to characterize the virgin bitumen and snail shell ash. Pulverized proportions of the snail shell ash were blended with bitumen at 10 %, 20 %, 30 %, 40 % and 50 % respectively by weight of mineral aggregates; and subsequently incorporated as filler at the same proportions. The rotational viscometer and penetrometer were engaged to determine the viscosity and penetration of the modified bitumen, and the Marshall mix design method was used to determine the mechanical and rheological characteristics of the resultant asphaltic concrete composites. The modification of bitumen with snail shell ash resulted in a decrease in penetration of virgin bitumen from 80/100 pen to 60/70 pen, including the rotational viscosity. Different mixtures of PSSA at the aforementioned proportions, were evaluated by the design method according to Marshall. The stability was found to be higher than the control mix at 30% of grade which satisfied the Marshall specification for wearing course mixes. X-ray fluorescence (XRF) showed the presence of Oxygen and Calcium in the Hot Mix Asphalt (HMA) modified with PSSA, while the scanning electron microscope (SEM) showed a good blend of the aggregates. The results suggest feasible use of PSSA as partial aggregate substitution in HMA. It was noted that the PSSA was finer than the conventional mineral filler and it filled the voids, engendered a stiffer, and denser mix, as well as reduced the number of voids present in the mix and increased its stability. Experimental results indicated higher stability value of 35.08 KN for the mixture having 30% PSSA as optimum filler content in comparison with conventional mix which was 34.7 kN and standard specification of 34 kN minimum. This study has therefore established the feasibility of using PSSA as alternative filler instead of the conventional in asphalt concrete mix by satisfying the standard specification. Also making the reuse of agricultural waste possible, thereby making construction cost cheaper, and also reducing waste.