Creep behavior of epoxy resin anchor for carbon fiber reinforced plastic sheet embedded in concrete

Abstract

Creep behavior of the epoxy resin anchor for CFRP sheet embedded in concrete was studied. Creep tests in 20°C and 40°C with the sustained loads of 3.0kN and 4.5kN were conducted for 42 days (1000 hours), where 3.0kN corresponded to the design load for the anchor. As a result, it was found that the creep displacement in the 40°C test was very large at the beginning of loading compared to the 20°C test. The glass transition temperature, Tg, was assumed to be the reason for the large creep displacement in the 40°C test. Therefore, Tg, tensile strength, and tensile modulus of elasticity were measured with various curing conditions for the epoxy resin. The measured Tg was 41°C with 23°C-7 days curing and it increased up to 57°C for 7 days in case the curing temperature was increased from 23°C to 40°C. In addition, it was found that the tensile strength and the tensile modulus of elasticity showed linear relationship with Tg in the range of 41°C to 57°C, and the tensile modulus of elasticity in 40°C was 40% of that in 20°C when Tg was 45°C. The curing condition for 45°C of Tg was equivalent to the beginning of the 40°C creep test. Thus, it was concluded that the reason for the large displacement in the 40°C creep test was because Tg was relatively close to the test temperature.