Analysis and Optimization of Tensile Strength for Loess Stabilized by Calcium Carbide Residue

Calcium carbide residue (CCR) can be reutilized to solidify the loess for road construction as a base or subbase due to its rich ${\mathrm{Ca}(\mathrm{OH})}_2$ facilitating pozzolanic reaction with water and soil particles. This study examines the effect of curing time, CCR contents, and dry unit weights on the tensile strength ($R_t$) of CCR-stabilized loess through the splitting tensile test. Aiming to predict the $R_t$ values, the ratio of porosity ($n$) controlled by compacted effort and initial volumetric CCR content ($L_{iv}$), namely $n/L_{iv}$, was chosen as a prediction parameter and then modified to $n/L_{iv}^{0.064}$ for compatible variation rate with $R_t$ values. A prediction model for the splitting tensile strength of CCR-treated soil was proposed considering the modified ratio $n/L_{iv}^{0.064}$ and curing days. The results indicate that $R_t$ values showed a nearly linear positive correlation with CCR contents and dry unit weights, logarithmic increase with the extension of curing time, but no apparent relationship with the ratio $n/L_{iv}$. The modified ratio $n/L_{iv}^{0.064}$ can reflect the trend of $R_t$ values at different curing days since the coefficients of determination were almost greater than 0.90 except for the specimens cured for seven days. The proposed prediction model had a good fit for laboratory data with 97% acceptability and close to 3% error. It can be applied for estimating the $R_t$ values of CCR-stabilized loess using curing time and an optimized ratio of porosity and initial volumetric CCR content. From the aspect of practical engineering, the reutilization of CCR can reduce construction costs, waste disposal costs, and environmental pollution.