Optimization and performance evaluation of hybrid nanoparticle systems in cold-region geotechnical applications

Abstract

This study aims to optimize the mechanical performance of hybrid nanoparticle-modified clay soils under different environmental conditions using a macro-micro characterization approach. In this research, nanoclay (NC), nanosilica (NS), and nanocalcite (NK) nanoparticles were added to clay soils obtained from Elazığ, Türkiye, in single, binary, and ternary hybrid combinations. The prepared samples were subjected to comprehensive experiments under different curing times (0, 7, and 28 days) and repeated freeze-thaw cycles (0–15 cycles). According to the results, the addition of nanoparticles improved the plasticity of the clay, densified the void structure, and significantly limited freeze-thaw cycle-induced mass losses and volumetric changes. In particular, the triple hybrid combinations (S17 and S18) exhibited the highest mechanical strength after freeze-thaw cycles at the end of the 28-day curing period. Sample S18 showed the most stable performance among all groups, with a 143.53 % increase in UCS after 15 cycles. Microstructural analyses confirmed that nanoparticles reduced porosity to 1.78 % by forming gel phases and filling microvoids. Gray correlation analysis revealed that the most dominant factor on strength was mass loss control, and the optimized performance that minimized mass losses and volumetric changes was achieved with a balanced hybrid nanoparticle combination (NC + NS + NK) at 0.25 % concentration combined with a 7-day curing, which maximized structural stability and was the most effective design configuration.