Experimental investigation of HPMC inhibited crack sensitive of coral mud under extreme environmental conditions

s Coral mud, widely distributed in the South China Sea, is highly prone to cracking, posing challenges for engineering applications. Hydroxypropyl methyl cellulose (HPMC), with superior water retention and crack inhibition capacity under hot and humid conditions, was introduced to improve the crack resistance of coral mud. This study conducted cracking and tensile tests to evaluate the effects of HPMC dosage (four levels) and environmental conditions on the cracking behavior and mechanical properties of coral mud. Results show that temperature and humidity markedly regulate water evaporation, with high temperature significantly accelerating moisture loss. HPMC effectively enhanced water retention and delayed cracking, with a 0.25% dosage providing the optimal performance. It restricted crack length and refined crack width distribution while having little influence on crack orientation. The modification efficacy was strongly dependent on environmental conditions, showing the most significant improvement under high temperature and high humidity, where a 0.25% dosage markedly enhanced crack resistance. Tensile tests confirmed that HPMC enhanced interparticle bonding and force transfer, particularly under high water content, whereas the effect was limited under low water content. This paper discussed the dual mechanism of HPMC to suppress cracking in coral mud by regulating evaporation and enhancing cohesion based on experimental results. Its findings provide practical guidelines for dosage and condition-specific application, supporting sustainable infrastructure development in the South China Sea.