Assessment of engineering and environmental suitability of waste bituminous concrete containing waste biomass ash

Abstract

This work presents a novel approach to utilize waste wood ash (WA) generated from incineration of fuelwood as filler in bituminous concrete mixes. The bituminous mixes containing WA was designed as per Marshall mix design, and their engineering properties were compared with the mixes containing hydrated lime (HL) at equal mass proportions ranging from 4–7%. The performance of bituminous mixes was compared using methods like static creep test, indirect tensile strength test, Cantabro test, retained Marshall stability test, active and passive analysis. The economic and environmental feasibility of both types of mixes were also analyzed by comparing their cost and greenhouse gas emission. Additionally, the mastics containing b oth fillers at the filler-binder ratio in the range of 0.6–1.2 were prepared and their viscoelastic properties, as well as rutting (after short-term ageing) and fatigue (after long term ageing) resistance, were analyzed using multiple stress creep and recovery (MSCR) and linear amplitude sweep (LAS) tests respectively. Mastics containing WA displayed higher fatigue life and marginally lower rutting resistance than HL mastics. Irrespective of the type of filler, rutting, and cracking resistance of both bituminous mixes were found to increase with the quantity of filler. At optimum filler content, WA mixes exhibited 10, 30, and 41% lower moisture, cracking, and raveling resistance than conventional HL mixes. However, WA mixes also consumed relatively lower optimum binder content and found to be 7% more cost-effective and 62% more environmentally friendly than HL mixes. The overall conclusions of this study ascertain the utility of WA as an alternative filler in bituminous concrete.