Performance enhancement of road base material using calcium carbide residue and sulfonic acid dilution as a geopolymer stabilizer

Abstract

Alkali activated industrial waste/by-product geopolymers have recently gained extensive attention from researchers as a replacement for cement in concrete manufacturing. However, little attention has been given to their employment as a stabilizer of unbound granular base/subbase (UGB) materials in road construction. Stabilizing granular base materials with geopolymers is explored in this study. The investigated geopolymer is composed of calcium carbide residue (CCR), a waste product resulting from the manufacturing of acetylene gas, which activated by a linear alkyl benzene sulfonic acid (LABSA). Four proportions of sulfonic acid dilution ratios and seven solid/liquid (CCR/diluted LABSA) mixes were prepared. The unconfined compressive strength (UCS) of the mixtures was determined in the laboratory. The maximum UCS was achieved by blending a diluted LABSA of (300/1000) ml with a geopolymer (solid: liquid) blend proportion of (80%:20%) by the total weight of aggregate. Based on the results, aggregate mixtures of 2.5%, 5%, 7.5%, and 10% of geopolymer blend content were prepared to determine the maximum UCS value corresponded to the optimum geopolymer mixing ratio. This optimum geopolymer ratio was recommended at 7.5%, which was then exposed to different curing times and environmental conditions to explore the variation in UCS as well as the elastic modulus (E). In addition, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) measurements revealed that the stabilized aggregate contained geopolymer gels generally produced microstructures that are more uniform and denser than the untreated aggregate structure. A blend of CCR and LABSA can be used as a feasible and sustainable eco-friendly alternative as a stabilizing agent for UGB in pavement engineering applications.