Engineering and Mineralogical Evaluation of a Rapid-Strength Stabilizer for Expansive Clays

Rapid stabilization of expansive soils has significant potential to support infrastructure development, particularly highway pavements. Historically, several studies have attempted to develop a stabilizer that can rapidly convert weak soils to strong soils with little manipulation and straightforward construction protocol. Often, such studies have recommended the use of non-Traditional stabilizers that have not been widely implemented. This study aimed to develop and evaluate the use of a mixture composed of conventional stabilizers such as lime, metakaolin, and sodium silicate for rapid strength gain of expansive soils. A simulant soil composed of smectite, kaolinite, and quartz was used to evaluate the stabilizer. The optimum mix design for rapid strength gain was determined by varying the amount of lime, metakaolin, and sodium silicate. The proposed mixture was composed of 4% lime, 3% metakaolin, and 3% sodium silicate by weight of soil, respectively. Engineering characterization results showed a 170% increase in strength within 24 h of treatment. The durability of the treated soil was also evaluated by recording the strength after 3, 7, and 9 cycles of wetting and drying, respectively. The results indicate that the stabilizer performance is on par with the simulant soil treated with the optimal amount of lime and cement. Microscale characterization using scanning electron microscopy-energy dispersive spectroscopy and nanoindentation provided insights into the stabilization mechanism of the treated soil. Scanning electron microscopy demonstrated the formation of pozzolanic products such as (C,N)-A-S-H, which is attributed to the soil's rapid stabilization.