Strength and microstructure characteristics of red-bed weathered residual soil stabilized by Titanium Gypsum-Cement

Abstract

Due to its unfavorable engineering characteristics, the red-bed weathered residual soil (RBRS) frequently necessitates remedial measures to conform to design specifications. Solidification with the aid of binders stands out as a prevalent technique employed to enhance the engineering attributes of RBRS. This study investigates the characteristics of RBRS stabilized with Titanium Gypsum-Cement (TGC) by conducting unconfined compressive strength tests on solidified soil with varying contents and curing times. Additionally, SEM and MIP tests were conducted to analyze the internal structure change, reaction mechanism, and hydration characteristics of the TGC-stabilized soil. The experimental findings revealed that the stress-strain response of specimens with varying proportions and curing times exhibited four distinct phases, namely the compaction stage, linear elastic deformation stage, pre-peak failure stage, and post-peak stage. Increasing cement content led to greater ductility in the stress-strain curve, while a higher ratio of TG to cement in the admixture resulted in a milder trajectory with a gradual decline in unconfined compressive strength. The stabilized soil with TGC ratio 6:4 (10%) and 9:6 (15%) met the compressive strength requirement at curing times of 7, 14, and 28 days. Microscopic investigations revealed the formation of hydration products, including CSH, with the incorporation of TGC. The resulting three-dimensional network effectively enveloped soil particles, enhancing inter-particle bonding and permeating mesopores and macropores, leading to soil structure compaction.