Durability of rubber waterstop in extreme environment: effect and mechanisms of ultraviolet aging

In harsh environments such as high altitude areas, the durability of rubber waterstops is a big concern. A long period of sunshine and the accompanying strong ultraviolet (UV) radiation accelerate the photooxidation and thermal oxygen aging of rubber waterstops, resulting in cracks, peeling off and even failure of waterstops. This study aims to investigate the performance of a widely used waterstop in simulated high altitude areas of western China by placing rubber waterstops in an UV aging chamber for 18, 36, 54, and 72 days. Mechanical properties, such as tensile strength, elongation, tear strength, compression set, and hardness, were measured. Moreover, scanning electron microscopy with X-ray microanalysis (SEM-EDS) and Fourier infrared spectroscopy-attenuated total reflection (FTIR-ATR) detection were performed on the damaged specimens to dissect the underlying mechanisms of deterioration in mechanical properties. The results showed that all the investigated mechanical properties of the rubber waterstop deteriorated with the increase in aging time. The increase in the UV aging time increased the surface cracks, decreased the unsaturated bonds, and increased the oxygen content and oxygen-containing functional groups of the rubber waterstop. It can also be found that the additive particles in the matrix gradually aggregated, and concurrently the carbon black particles decreased, which weakened the three-dimensionality of the cross section of the specimen. Findings from this paper provide new insights into the durability of rubber waterstops in high altitude areas.