Investigation on use of silica based additive for sustainable subgrade construction

Abstract

This study presents the potential application of cement and StabilRoad, a silica based additive for subgrade soil stabilization. The coupling effect of soil, cement and StabilRoad additive has been evaluated by compaction characteristics, California bearing ratio (CBR) and Unconfined compressive strength (UCS) at various percentages of cement along with this additive. The underlying mechanism that contributes to the stabilization process was visualized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The result indicates an enhancement in mechanical performances of the soil mixture containing this additive. CBR value and UCS were increased by 72.413 % (soaked condition) and 79.16 % (28 days) on addition of 1 % StabilRoad to the cement modified soil mixture. Meanwhile, different regression models namely, quantile regression (QR), partial least square regression (PSL-R), and linear regression (LNR) models have been developed to establish the relationship of UCS and CBR with routine properties of subgrade soil. LNR model attained the highest predictive accuracy in all cases. An increase in the intensity of C-S-H peaks has been observed with the incorporation of this additive which is responsible for enhanced strength in the modified soil mixture. Subgrade stabilization with this additive also resulted in reducing the overall cost by minimizing the crust thickness of the pavement. Therefore, the present investigation confirms the usability of cement and StabilRoad in subgrade stabilization with significant economic benefits.