Enhancing the resiliency and sustainability of collapsible soils using nano calcium carbonate: a self-healing perspective

This study aims to investigate the mechanical properties and self-healing capability of collapsible soil treated with nano calcium carbonate. In this regard, soil samples were treated with varying contents of nano calcium carbonate and subjected to unconfined compressive strength (UCS), ultrasonic pulse velocity (UPV), and large-scale direct shear tests. The results revealed that the optimal content of nano calcium carbonate was 0.4%, which significantly enhanced the compressive and shear strengths. Moreover, under saturated conditions and after crack formation, samples treated with nano calcium carbonate experienced less strength loss. They exhibited a higher self-healing index, especially the sample containing 0.4% nano calcium carbonate, which was able to recover about 60% of the lost strength after 28 days. Additionally, the strong exponential correlation between UPV and UCS results (R2 = 0.902) indicates that the UPV test can be used as a non-destructive method to monitor the self-healing process