Investigation of pull-out characteristics of connections for post-installed rebar utilizing mortar-based binders and chemical adhesives

Abstract

ABSTRACT In this study, various types of adhesives were tested for their ability to adhere steel reinforcement bars to old concrete during a pull-out test when they were used in connection to a post-installed re-bar. The cylinder samples were 150 mm in diameter and had anchors made of rebar that varied in diameter (8 mm, 10 mm, 12 mm, 16 mm, and 20 mm) and embedded depth (10, 12.5, 15, and 20 times the rebar diameter). In contrast to the control group of (60 Nos.) cast-in-situ rebar concrete specimens, the other samples (240 samples) were post-installed-rebar concrete specimens with various bonding agents, epoxy-based chemical adhesive, vinyl-ester-based chemical adhesive, and cement-based binders (geopolymer mortar, conventional mortar). The results showed that while they all performed better than cement-based mortar-bonded specimens, the use of the epoxy-based chemical adhesive and vinyl-ester-based chemical adhesive pull-out load values were closely related. The anchorage depth and rebar diameter both improve the bond strength which reflects in terms of pull-out load. The anchorage depth and the region of contact with the adhesives or binder determine the failure mechanism of post-installed rebar connections. Due to the higher strength at the interface between the binder and the rebar in comparison to the binder-concrete, larger rebar diameters favour splitting or failure of concrete.