Compressive Mechanical Properties and Water Absorption of Glass fiber-reinforced Plastics Pipes Aged in Caspian SeaWater

Glass fiber-reinforced plastics (GFRPs) have been widely used in marine structures, recently. In this paper, the water absorption and compressive behaviour of pultruded fiber-reinforced plastic pipes (GFRPs) after immersion in Caspian sea water and distilled water for 1, 7, 14, 21, 28, 35, and 40 days is experimentally investigated. In this respect, the specimens are submerged in Caspian seawater and distilled water and then their water absorption rate, length, and their compressive strength were measured every day. The compressive mechanical properties of the specimens in the as-received and water-aged states are obtained using quasi-static compression tests. The amount of water absorption and length change due to immersion in these two cases have also been investigated. After 40 days, the average relative humidity absorption of the samples in Caspian Sea water and distilled water were 2.88% and 2.89%, respectively. It was observed that after immersion in both Caspian Sea water and distilled water, the final compressive strength and absorbed energy of the pultruded pipes increased.