The effect of nano-CuO on mechanical, microstructural, and self-healing properties of clayey sandy soils

The present study aims to evaluate the effect of Nano-CuO addition on mechanical, microstructural, and self-healing properties of clayey sandy soil. For this purpose, scanning electron microscope (SEM) and unconfined compressive strength (UCS) tests were conducted on sandy soils with different percentages of clay (10, 20, 30%) stabilized with Nano-CuO (0.3, 0.6, 0.9, and 1.2wt.% of soil) at the curing times of 7, 14, and 28 days. Further, the group method of data handling (GMDH) neural network was used to determine the optimal amount of clay and Nano-CuO to achieve maximum undrained cohesion (Cu). The results indicated that self-healing of the sample stabilized with 0.9% Nano-CuO at 28-day curing time was 73% higher than the unstabilized sample. SEM images showed that the addition of Nano-CuO could improve soil microstructure by reducing the number and size of pores. Finally, the results of group method of data handling (GMDH) highlighted that the optimum values of fine grains and Nano-CuO to achieve the maximum Cu are equal to 25 and 0.87%, respectively.