Effect of Hygro-Thermal Environment on the Mechanical Properties of Magnesium Oxide Boards

Magnesium Oxide (MgO) boards are gaining popularity in the global construction industry, with a projected compound annual growth rate (CAGR) of 5.4%. Despite their increasing adoption in the Australian construction and housing industry, there is a limited understanding of their in-service mechanical performance especially under extreme weather (e.g., hygro-thermal) conditions. This study evaluates the effects of exposure for four months to high moisture and temperature (98% relative humidity and 60˚C temperature) on the mechanical properties of magnesium sulphate-based MgO boards. Experimental tests were conducted to assess moisture absorption, compressive, bending and shear properties. The results indicate a significant reduction in mechanical performance under hygro-thermal exposure, with compressive strength decreasing by 55%, bending strength by 32%, and shear strength by 35%. Moreover, the magnesium sulphate-based MgO boards were found to absorb up to 20% of moisture when exposed to hygrothermal conditions for four months. These findings highlight the material’s susceptibility to environmental factors, emphasizing the need for careful consideration in design and application. The study provides valuable insight into the selection of magnesium sulphate-based MgO boards and taking necessary adjustments to ensure durability and structural integrity of projects exposed to varying moisture and temperature conditions.