Classification of rainfall in the country.

A key challenge in highway reconstruction and expansion projects is to reduce longitudinal cracking at the junction of old and new roadbeds, which is a critical issue in the maintenance of transportation infrastructure. Polymer grouting technology, a non-excavation method for hidden subgrade defects, leverages material self-expansion properties to fill voids, enhance load-bearing capacity, and bond structural layers while providing seepage control—enabling rapid repair of longitudinal pavement joints. This study investigates the seepage characteristics of polymer-grouted longitudinal joints in reconstructed pavements by simulating post-repair infiltration behavior under rainfall conditions. The results elucidate the anti-seepage efficacy of polymer grouting, offering theoretical and practical insights for efficient longitudinal joint treatment in highway expansion projects.