Interface engineered glass fibers improve performance and durability of stabilized silty clay

Freeze-thaw cycles (FTCs) weaken stabilized subgrade soils in cold regions by promoting cracking, pore coarsening, and strength loss. In this study, glass fibers (GFs) were modified with γ-aminopropyltriethoxysilane (KH550) and epoxy resin to obtain modified glass fibers (MGFs), and nano-TiO₂ was further anchored to obtain reinforced glass fibers (RGFs). Cement-metakaolin-stabilized silty clay (CMS) was used as the matrix to evaluate mechanical performance, permeability resistance, and freeze-thaw durability. The 28-day compressive strengths of MGF-1.25% and RGF-1.25% reached 4.25 and 4.98 MPa, increasing by 30.37% and 52.76% compared with CMS. After 20 FTCs, strength retention increased by 17.1% and 22.1%, with reduced permeability. X-ray photoelectron spectroscopy (XPS), mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM) analyses revealed stronger interfacial bonding, refined pores, and enhanced formation of hydration and polymerization products, providing a design route for durable cold-region subgrade materials in transportation infrastructure.