Long-Term Strength Evolution of Calcium Carbide Residue-Treated Highly Plastic Clay Soil

Abstract

The study focuses on using industrial waste, specifically calcium carbide residue (CCR), to enhance the workability and durability of highly plastic clay. The effectiveness of CCR modification is evaluated by comparing the initial CCR fixation point based on pH value, methylene blue value (MBV), unconfined compressive strength after curing for 28 days, and the strength of 120-day cured samples with and without wetting-drying cycles to characterise their long-term reactivity. The microstructural analysis using SEM-EDAX, XRD, and FTIR qualitatively evaluates the reaction mechanism assisting in strength gain and retention after moisture changes after curing. The SEM study reveals that cementation products fill the voids with extended curing from 28 to 120 days and transform calcite crystallites into needle-like particles. In soil with a high calcium concentration, the XRD and FTIR ex-amination traces the existence of carbonates that produce acicular calcite crystals and hy-drates. The optimum CCR is 9%, which effectively imparts high strength and resistance to moisture fluctuation-induced deterioration. The findings will be significant in selecting the optimal soil-CCR mix for highly plastic clay.