ACI tested 16 pullout specimens to investigate the effect of curing conditions on bond behaviour of near-surface-mounted (NSM) carbon fiber-reinforced polymer (CFRP) strengthening concrete under curing temperatures from 35 to 65°C (95 to 149°F) and curing times from 6 to 12 hours.
ACI says: “It was compared to that of specimens in ambient conditions (16°C [60.8°F]). On these bases, a nonlinear local bond-slip model was proposed. Two key parameters—A and B—are employed in the proposed bond-slip model, the specific expressions of which were mainly related to ultimate pullout load and peak shear stress of the specimen.”
The results show that the bond behaviour of CFRP strip represents a negative quadratic curve with curing temperature and positive inverse tangent curves with curing time.
“The nonlinear local bond-slip model, considering the curing temperature-time, is deduced and validated,” ACI adds.
This paper was written by Er-yu Zhu and Ze-wen Zhu.