Research on Durability of Sealants Used in External Wall Joints of Prefabricated Concrete Buildings

Sealant materials serve as the primary waterproof barrier for the external walls of prefabricated concrete buildings. Their durability is a crucial performance indicator, directly influencing the effectiveness of waterproofing and service lifespan of buildings. Therefore, the assessment of sealant durability is a critical area of research with substantial practical implications. This study evaluates the durability characteristics of three commercially available sealant types: one-component modified silicone, two-component modified silicone, and polyurethane sealants. A comprehensive testing program was conducted, involving specimen preparation and subsequent exposure to four distinct aging conditions: natural aging, thermal aging, UV aging, and accelerated artificial climate aging. This study aimed to effectively assess the influence of various aging conditions on the evolution of the physical and mechanical properties of the abovementioned sealant materials. The aged sealants were characterized using Fourier-transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and volumetric swelling tests to analyze the aging mechanisms of the different sealant structures. Furthermore, the coefficient of variation method was employed to assess the durability performance of the three sealants. Testing results revealed distinct sensitivity patterns to aging conditions among the different sealant structures. The one-component modified silicone sealant demonstrated comparable sensitivity to thermal aging, UV aging, and artificial climate aging, exhibiting superior durability performance. By contrast, both two-component modified silicone and polyurethane sealants showed increased sensitivity to UV aging and artificial climate aging conditions.