Fracture and long-term aging characteristics of GFRP clamping plates for improved movable weirs

Abstract

In this study, the durability of movable weirs was improved by replacing steel clamping plates with glass fiber-reinforced polymer (GFRP) material. Because the clamping plates of movable weirs are always in contact with water, the service life of weirs is reduced due to corrosion. Other environmental conditions also degrade movable weirs, such as exposure to continuous inundation, dry environments, repeated dry and wet conditions, and chemical environments. This study evaluated the absorption, fracture, and long-term aging properties of GFRP clamping plates for improved movable weirs. Absorption increased with immersion time in 60°C tap water, sodium sulfate (Na2SO4) solution, or calcium chloride (CaCl2) solution. However, the total absorption for 50 days and 100 days exposure was low, less than 0.50% and 0.62%, respectively. In fracture load tests, the GFRP clamping plates showed the largest reduction in strength after exposure to the CaCl2 solution; 70% and 67% of the control load were retained for exposures of 50 days and 100 days, respectively. After exposure to both tap water and the Na2SO4 solution, the GFRP clamping plates showed residual strengths of 77% and 69% after 50 days and 100 days exposure, respectively. The GFRP clamping plates showed 74% and 71% residual strength after exposure to repeated freeze–thaw environments for 50 days and 100 days, respectively, and 80% residual strength after exposure to all other environments for 50 days or 100 days. Both vertical and horizontal cracks were generated before fracture after exposure to an environment involving direct contact with moisture. Without moisture, only horizontal cracks were generated before fracture.