Experimental study of geopolymer used as adhesive in anchorage of steel bars

Pull-out tests were performed on 42 post-installed steel bars embedded in two large concrete substrates. Three types of adhesive agent, including commercial available organic adhesive (Hilti HiT-Re), inorganic geopolymer paste and geopolymer mortar were used to bond the post-installed reinforce bars, with different embedment length (5d, 8d, 10d, 12d and 15d, where d is the diameter ). Data from the pull-out tests is utilized to compare the bond performance of the three types of adhesive agent and determine the optimum embedment depth of rebars when using geopolymer paste and geopolymer mortar as adhesive. The test results showed that the failure modes of the post-installed rebar system changed from concrete cone failure to combined failure or even rebar fracture failure, with an increase in the rebar embedment depth. When the embedment length of post-installed rebars was less than 10d, the specimens bonded with organic adhesive exhibited the best bond performance, and which were followed by those bonded with geopolymer mortar. And the specimens bonded by geopolymer paste exhibited the lowest bond strength. However, for specimens with rebar embedment depth higher than 10d, the anchoring behavior of three types of adhesive was similar.