<p>In this study, the self-healing, mechanical, shear and microstructural characteristics of clayey sand stabilized with nano-copper oxide (NC) are investigated using the velocity of ultrasonic pulse waves. For this purpose, the samples were made with NC weight ratios of 0, 0.4, 0.8, 1, and 1.2% and were cured for 0, 7, 28, and 11 days. In this study, standard Proctor tests, liquid limit (LL), plastic limit (PL), unconfined compressive strength (UCS), indirect tensile strength (ITS), ultrasonic pulse wave velocity (UPV) and direct shear test were conducted to evaluate the effect of NC on the mechanical, shear and microstructural characteristics of clayey sand. Furthermore, Scanning Electron Microscopy and Atomic Force Microscopy analyses were conducted to investigate the microstructural behavior. Relationships between these parameters and UPV are established. The research showed that stabilizing clayey sand soil with NC will decrease the maximum dry density (MDD) and increase the optimum moisture content (OMC) of clayey sand soil. Adding 1.2% of NC decreased the MDD by 1.6%. The optimum content of NC to achieve the maximum value of UCS, ITS, and shear strength parameters of clayey sand soil equals 1%. Adding 1% of NC increased cohesion and internal friction angle by 205% and 21%, respectively. Also, the results of the ultrasonic pulse test can be used with appropriate accuracy to estimate the mechanical and shear parameters of the clayey sand soil stabilized with NC. The maximum value of the self-healing index occurs for the sample stabilized with 1% nano-copper, equal to 39%.</p>