Zero-energy solution for thermal cracking to concrete: High-altitude anti-cracking coating based on radiative cooling

Concrete expansion and cracking at high altitudes present persistent challenges in construction, primarily due to extreme solar radiation and low night temperatures. Current mitigation strategies largely overlook energy regulation, relying instead on material modification and subsequent repair. However, these approaches fail to address the root cause of thermal cracking: Excessive temperature gradient within the concrete and constant temperature stress fluctuations. Recognizing that mitigating the excessive solar energy input at high altitudes is the key to solving this problem, this study introduces a high-altitude anti-cracking coating (HAAC) designed to leverage radiative cooling technology. The coating employs an innovative cooling strategy to reduce the temperature gradient and mitigate stress fluctuations in the concrete from the source successfully achieving zero-energy thermal protection for the concrete. Preliminary outdoor cooling tests, high-altitude concrete thermal protection tests, and thermal stress analyses were conducted on these materials. The results show that the application of HAAC to the concrete substrate reduced the maximum temperature by 9.9°C, decreased the day-night temperature differential by 10°C, lowered the surface thermal stress by 1.1 MPa, and limited the maximum thermal stress to only 1.9 MPa. Additionally, HAAC exhibited good weathering resistance, offering long-term thermal protection to concrete. These attributes make HAAC suitable for large-scale construction projects in high-altitude areas.