Experimental study on hygrothermal deformation of foamed ceramic insulation decorative board under accelerated aging conditions

Insulation decorative boards (IDBs) have been widely accepted as a novel exterior insulation material. However, the mechanism of the temperature and strain change between the IDBs and the substrate wall in extreme climate is not clear. Therefore, the aim of this study is to examine the evolution of the temperature and strain between the IDBs and the substrate wall in an artificially accelerated aging environment. The heat-rain cyclic test with the maximum temperature of 70 ℃ and the spray volume of 1 L/m².min was initially carried out 80 times on the external thermal insulation composite system (ETICS) with large-size foamed ceramic IDBs. The temperature and strain fields at the interface were then monitored and collected through 22 temperature and humidity sensors and 22 strain gauges, each. Results indicate that the temperature and strain at the interface represent significant non-uniform distributions. The fitting results of the temperature and strain demonstrate that the average temperature and horizontal average strain at the interface linearly increase with the number of heat-rain cycles. Whereas the vertical average strain increases parabolically with the number of heat-rain cycles. This phenomenon is primarily related to the rising temperature caused by the unbalance between the heat flowing into interface in the early-cycle stage and flowing out of interface in the late-cycle stage rather than the self-performance degradation of the IDB. The observation results in this paper have a reference significance for analyzing the temperature and strain change mechanism at the interface between the IDB and the substrate wall. This can provide a reference for analyzing the thermal insulation and deformation of the IDBs’ external insulation system, and guide its design and construction, accordingly.