DURABILITY OF GFRP REINFORCING BARS IN ALKALINE ENVIRONMENT

This paper describes research in which accelerated aging tests are being carried out on more than 20 types of glass fiber reinforced polymer (GFRP) reinforcing bars made from different combinations of constituent materials; manufacturing parameters, sizes, and shapes; and surface coatings. The specimens are being subjected to various sustained tensile loading in 3 types of alkaline environments. Time to rupture or residual strength, as applicable, was determined. Further, stress corrosion mechanisms were evaluated by micro structural analyses. The results indicate that alkaline ions and moisture can penetrate or diffuse through the resin to the interphases and the fibers. For GFRP bars embedded in moist concrete under varying sustained stress levels, 3 types of stress corrosion mechanisms have been identified.