Multi-scale investigation of mechanical properties and solidification mechanisms of diverse cementitious materials for solidifying subgrade talik in permafrost regions

Abstract

Permafrost degradation enlarges subgrade taliks characterized by high moisture content and low bearing capacity, resulting in weakened soil properties that threaten long-term subgrade stability. Grouting reinforcement using cementitious materials has proven effective for talik stabilization. However, despite the diversity of available cementitious materials, their applicability for subgrade talik solidification remains insufficiently studied, and the reinforcement mechanisms are poorly understood. Therefore, this study employs isothermal calorimetry, X-ray diffraction (XRD), thermogravimetric analysis(TGA), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) to investigate the mechanical properties and micro-mechanisms of taliks solidified with four materials: RT (mineral-based), PMC (polymer-modified cement), KFS (anti-dispersion grout), and PLH (low-heat cement). It further explores the applicability of each material in cold region engineering projects. Results show that different cementitious materials exhibit different hydration heat release patterns in early and late stages. RT demonstrates a relatively low overall heat release, whereas KFS shows the opposite trend. The heat release from highest to lowest in 48 h is KFS (201.91 J/g), PLH (184.25 J/g), PMC (176.67 J/g), and RT (165.77 J/g). Moreover, the strength of KFS-solidified soil is higher than that of the other groups at all curing ages. Additionally, PMC exhibits good thermal stability and appears more suitable for projects in cold regions with significant temperature changes. Through grey relational analysis, the important factors affecting the compressive strength of solidified soil have been identified. This study provides a valuable reference for the innovation and application of cementitious materials in cold region engineering projects.