Utilization of Ferrochrome Slag in Bitumen Base Stabilisation

Abstract

The industrial waste such as steel slag, copper slag etc. in road construction industries is gaining significant importance in India considering the disposal, environment problems and gradual depletion of natural resources like aggregates and soil. These industrial waste products can be employed in the building of various layers of road pavement either as full replacements for standard materials or in combination with cement/lime with or without chemical stabilisers. Through experimental examination, the current study investigates the engineering features of ferrochrome slag, an industrial waste, with the goal of improving its applicability as a subgrade, subbase, and base material for road building.

Bitumen binder (VG-10) with three different RAP material percentages (45%, 65%, 85%) and two different slag content (with slag and without slag), along with two different binders (Foam bitumen and emulsion bitumen) were considered in this research study. Detailed laboratory performances of FBM and EBM as well as foaming characteristics were investigated. The foam was characterized for expansion ratio and half-life. The ideal foam binder and emulsion binder contents of the mix were determined statistically using the response surface technique (RSM). The effects of different percentages of RAP material and slag content on the resilient modulus, split tensile strength, tensile strength ratio, conditions of FBM and EBM were evaluated. Image analysis and X-ray diffraction pattern (XRD) were used to visualize the effect of different percentages of RAP material and slag content of FBM and EBM. The main harmful element found in the ferrochrome slag that is most likely to contribute to environmental pollution issues during use and disposal is chromium. Although there is a significant quantity of residual chromium in the slag samples, almost all of it is well immobilised in the spinel phase, allowing for very little chromium leakage from the slag samples. Results after exhaustive laboratory studies indicate that the warm aggregates having Slag content with 65% of RAP content gives the best performance of FBM and EBM.