Bond behavior of sand-coated CFRP rebars in SHCC under bending: Experiment and prediction

Abstract

This paper prompted experimental investigations on the bond behavior of sand-coated carbon FRP (CFRP) rebar in SHCC through hinged beam tests. The effects of the bond length, the rebar diameter, the cover thickness, the method of surface treatment, the matrix material, and the type of sand-coated FRP rebars on the bond performance were comprehensively discussed. The findings of the study revealed several important insights. Firstly, larger bond length and rebar diameter reduced both the bond strength and stiffness, while the failure mode changed from pull-out to splitting pull-out as these factors increased. Additionally, a change in cover thickness has great influence on the failure mode, the bond strength and stiffness of the specimens. Moreover, the bond performance of CFRP rebars was significantly enhanced by the application of the sand-coating. Notably, SHCC specimens exhibited comparable bond strength to concrete specimens, while showcasing greater post-peak bond toughness. To further understand the bond-slip behavior of sand-coated CFRP rebars in SHCC, a bond-slip constitutive model and a development length calculating method were also devised. These findings contribute to advancing the knowledge and understanding of the bonding characteristics between SHCC and CFRP rebars.