Low‐Molecular‐Weight Polyol Amine Modified Polyurethane Adhesive for Interlayer Gap Repair of Ballastless Track

ABSTRACT With the rapid expansion of China's high‐speed railway network, ballastless track has emerged as the dominant structural system. Under the coupled effects of repeated train dynamic loads and complex environmental conditions, interlayer delamination defects occur frequently and pose severe threats to operational safety. Grouting reinforcement for high‐speed railway gaps must be completed within the limited maintenance skylight period, imposing stringent demands on repair materials, including low viscosity, rapid curing, and high bonding strength. In this work, a novel polyurethane adhesive modified with low‐molecular‐weight polyol amine (MPA) was designed and synthesized. Results demonstrate that the optimal MPA content is 15 wt%. The modified adhesive exhibits superior fluidity, rapid curing behavior, and enhanced mechanical properties. After exposure to 50 extreme freeze–thaw cycles or 720 h of acid–alkali corrosion, the mechanical property retention rate remains above 75%, indicating excellent durability. Field tests verify that the adhesive satisfies the construction requirements of the skylight period and provides reliable technical support for the efficient restoration of interlayer gaps in ballastless tracks.