Preliminary Investigation on the Development and Performance of Self-immune and Self-healing Soil-Cement Systems Under Freeze-Thaw Cycles

Inspiration from biological systems has recently fuelled research in the built environment to develop smart materials that comprise sustainable and resilient systems, which similarly can continually adapt and respond to their environment. Many of these activities have so far focused on concrete for structural applications. However, to date there has been little work on the development of effective smart systems for geotechnical applications. Those systems and relevant geotechnical applications pose very different and more difficult and challenging problems compared to concrete and require a complete rethink of how to design such smart systems. The focus of the work reported in this paper is on the development and performance of self-immune and self-healing soil-cement systems subject to freeze-thaw (f-t) cycles. This was addressed with two types of microcapsules: SikaAer ^® Solid and Lambson microcapsules. Unconfined compressive strength (UCS), water content and volume stability were investigated after f-t cycles. By adding 1% (by soil mass) Lambson microcapsule, the UCS of 20% cement stabilised soil samples subjected 1–12 f-t cycles was improved by 21–40%. The f-t durability was also largely improved by adding 1% (by soil mass) SikaAer ^® Solid, where no deterioration in UCS was observed; change in volume and moisture content was largely reduced; and no crack formation was observed by optical microscopy after 10 f-t cycles. This study presents evidence of the significant potential for soil-cement system to possess self-immune or self-healing capabilities through the implementation of appropriate microcapsules.