Application and performance evaluation of TMUF-MPCMs in concrete pavement: Mechanical behavior and durability investigation

Concrete pavements in cold regions are highly susceptible to deterioration from freeze-thaw cycles, which challenge durability and maintenance. This study investigates the incorporation of 4 % and 6 % Tetradecane-Melamine-Urea-Formaldehyde microencapsulated phase-change materials (TMUF-MPCMs) in concrete mixtures to improve durability and thermal regulation. Microstructural analysis confirmed the successful synthesis of spherical, thermally stable microcapsules. While the addition of TMUF-MPCMs reduced workability (approximately 20 % slump reduction) and compressive strength (by 26 % and 30 % for the 4 % and 6 % mixes, respectively), flexural strength improved significantly, with the 6 % mixture exceeding FAA requirements. Most notably, TMUF-MPCMs dramatically enhanced freeze-thaw resistance, retaining over 90 % of their relative dynamic modulus of elasticity after 300 cycles compared to 76 % for conventional concrete, while exhibiting negligible mass loss and crack formation. Microstructural evidence suggests self-healing behavior through calcite precipitation at the microcapsule interfaces. A composite performance index ranked the 6 % TMUF-MPCM mixture as optimal, and multi-objective optimization identified 5.9 % as the ideal dosage to balance mechanical performance and durability. Despite some reduction in compressive strength, TMUF–MPCMs offer a promising dual-functional strategy to enhance the durability and sustainability of concrete pavements in cold regions. The self-healing response was confined to the microscale. At the same time, the potential reduction in deicer dependence is inferred from laboratory-based thermal and durability enhancements rather than verified under field conditions.