Enhancing Durability and Permanency of Problematic Soils Using Silica-Based Co-Additives with Calcium-Based Stabilizers

Construction of pavements and other lightweight structures on expansive soils is a considerable cause of concern for transportation infrastructure practitioners. Several researchers have recommended the use of silica-based co-additives with calcium-based stabilizers to overcome the problems associated with long-term performance of such infrastructures. However, very little focus has been directed towards understanding the durability and permanency of such treatment methods. A research program was developed to address issues regarding the durability and permanency of the nanosilica co-additive treatment when commixed with a traditional Ca-based stabilizer. Engineering tests such as soaked strength and volumetric swell measurements were performed to measure the moisture susceptibility. Unsaturated studies using soil water retention curves were performed to understand the pore structural changes after treatments. And finally, leaching studies on treated soils were performed to understand the efficacy of the nanosilica in preventing the loss of primary stabilizers. Experimental results showed that the application of silica-based co-additives with lime to treat high plastic problematic soil significantly changes the durability of the treated soils against moisture intrusion. The SWCC helped to understand the moisture-holding ability in different soils. And finally, the leaching test provided some preliminary insight on the effect of nanosilica in reducing the Na+ leaching, while not affecting Ca2+ leaching, as compared to only lime-treated soils. Overall, the study helped to develop a preliminary understanding of the behavior of the silica-based co-additive and lime treatments for long-term performance of transportation infrastructure.