Determination of Long-Term Mechanical Properties of XPS

This paper explores the long-term mechanical performance of thermal insulation materials, particularly extruded polystyrene foam (XPS), used under sustained heavy loads in building foundations. It discusses the key physical phenomena influencing mechanical behavior, including compressive creep, which describes time-dependent deformation under constant stress. The study employs mathematical models, such as the Findley equation, to predict long-term deformation, revealing that high-quality XPS maintains structural integrity with less than 2% thickness reduction over 50 years. European standards now mandate rigorous testing (over 608 days) to ensure insulation performance, considering creep deformation limits to maintain energy efficiency and structural stability. The findings underscore the necessity of selecting appropriate insulation materials for foundations to prevent excessive deformation and ensure long-term durability in building applications.

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