Bond behavior of the FRP grid-concrete interface with geopolymer mortar as an adhesive

Abstract

This study conducts an investigation into the effect of the geopolymer mortar (GPM) thickness on the bond behavior of the FRP grid-concrete interface. Eighteen specimens were tested under the single-lap shear loading to evaluate the effect of the mortar thickness (8/10/15/20/25 mm) and macro fiber reinforcement from failure mode, load response, strain distribution, and bond stress distribution. The study further assessed the applicability of existing calculation models for the FRP grid-concrete interface. The results indicate that the ultimate load initially increased and then decreased as the mortar thickness increased, and the macro fiber reinforced mortar enhanced the ultimate load. However, mortar thickness variation and macro fiber reinforcement had little effect on the failure mode, strain distribution, and bond stress distribution, while lager thickness and macro fibers significantly reduced crack occurrences. Additionally, existing models for the FRP sheet-concrete interface tended to underestimate the effective bond length and interface fracture energy of the FRP grid-concrete interface. Regression analysis, based on existing models, enabled the development of effective bond length and bond-slip relationships, showcasing satisfactory accuracy.