Experimental study of polyurethane-cement composite reinforcing talik beneath subgrade in permafrost regions: Exothermic characteristics, durability and micro-mechanism

Abstract

Permafrost degradation induces the expansion of talik, which has high water content, low bearing capacity, and high compressibility, constantly threatening the safe and long-term service performance of local engineering structures and practices. Therefore, adopting effective measures to address talik is of vital significance for the effective operation of engineering projects in permafrost regions. Utilizing polyurethane-cement composite to solidify talik to improve its mechanical properties. Evaluate its applicability in cold regions by analyzing the thermal conditions and durability. Characterize the micro-mechanisms of the specimens by scanning electron microscopy, X-ray diffraction and mercury intrusion porosimetry. The results show that the talik solidified by WPU10 has good water stability and relatively low strength damage during the freeze-thaw cycles. Freeze-thaw cycles affect the pore structure, the morphology of hydration products within the specimens, and the effective porosities of PUC and WPU10 increase by 62.44% and 59.58%, respectively. The incorporation of WPU can inhibit the occurrence and development of hydration reactions, and delay the hydration process. WPU has an optimal dosage, with a 10% content having the best effect. An insufficient dosage fails to fill the pores effectively, whereas an excessive one causes agglomeration and influences the cement hydration process. The research results provide an important reference for the innovation and application development of engineering materials in cold regions, and also for the treatment of talik.

Keywords

• Permafrost degradation
• Talik
• Polyurethane cement composite
• Durability
• Microstructure