Pull-out behavior of post installed rebar connections using chemical adhesives and cement based binders

This study investigated the effectiveness of several types of adhesives used in post-installed rebar connections as a bonding agent between steel reinforcement bars and old concrete under pull-out test. The cylindrical samples (96 + 24 Nos) of 15 dia. × 30 cm with anchors rebar of varying diameter (8, 10, 12 mm) with different embedded length (10, 15 and 20 × rebar diameter). The control (24 Nos) was the cast in-place rebar concrete specimens while other samples (96 Nos) were post rebar-installed concrete specimen of varied bonding agents-chemical adhesives (Sikadure-31CF and EPICHOR 1786) or cement-based binders (mortar, ultra-high performance self-compacting concrete (UHPSCC). The findings showed that the use of the adhesives and UHPCC pull-out load values were in close proximity while they all outperformed mortar bonded specimens. The pull-out load (bond strength) increases with the embedded length and the diameter of the rebar. Failure mode of post installed rebar concrete is governed by the embedded length and the area of contact with the adhesives or binder. Larger diameter of rebar favours splitting or failure of concrete due to higher strength in binder-rebar interface compare to binder-concrete interface.