Assessing the influence of using nano titanium dioxide on the microstructure behavior and geotechnical properties of clayey soil.

This study investigates the influence of nano–titanium dioxide (TiO₂) on the engineering behavior of cement-stabilized clay. Nano–TiO₂ was incorporated at contents of 0.2%, 0.5%, and 0.9% by dry soil weight, while cement was added at 2%, 4%, and 8%. A comprehensive experimental program, consisting of Atterberg limits, unconfined compressive strength (UCS), direct shear tests, and scanning electron microscopy (SEM) was conducted to evaluate the effects of nanoparticle addition on soil plasticity, strength, and microstructure. The Atterberg limits results show that nano–TiO₂ increases both the liquid limit and plastic limit, with a corresponding rise in plasticity index due to enhanced water adsorption and nanoparticle–clay interactions. UCS testing revealed that nano–TiO₂ significantly improved strength for specimens containing 4% and 8% cement, with optimal nanoparticle content varying with cement dosage. While increasing cement content increased stiffness, the addition of nanoparticles at constant cement levels did not meaningfully affect elastic modulus. Direct shear results demonstrated that nano–TiO₂ increased the internal friction angle but had minimal influence on soil cohesion. SEM analysis confirmed microstructural densification of the clay–cement matrix, with nanoparticles filling voids, enhancing particle bonding, and contributing to the observed strength improvements. Overall, the findings indicate that nano–titanium dioxide can effectively enhance the mechanical performance of cemented clay, particularly in terms of strength and frictional resistance, and that these improvements are strongly supported by corresponding microstructural modifications.