HIGH TEMPERATURE HEAT RESISTANCE OF CONCRETE CONFINED WITH CFRP USING FIBER REINFORCED GEOPOLYMER BONDING AGENT

Abstract

Rehabilitation and improvement of concrete structures by strengthening is an environmentally sustainable option compared to demolition and building of new structures. Epoxy resin is typically used as the bonding agent to strengthen concrete structures by using FRP. However, a major drawback of epoxy resin is that it loses bond strength by melting at high temperatures. Geopolymer is an alternative binder that possesses high resistance to elevated temperatures. This paper presents the results of CFRP confined concrete cylinders using 0.2% short PVA fiber reinforced geopolymer paste as the bonding agent. Concrete cylinders of 45 MPa were wrapped with one or two layers of CFRP and exposed to temperatures of 200, 400 and 800°C for 90 minutes and then tested for compressive strength. The specimens exhibited failure by tearing the CFRP fabric. The percentage of increase of strength by the CFRP wrapping at 800°C was 86% for one layer with fiber, 51% for one layer without fiber, 65% for two layers with fiber, and 73% for two layers without fiber. While strength of the cylinders increased with the increase of CFRP layers, the addition of PVA fiber did not have an obvious benefit to the strength enhancement. No melting, though cracks were observed in fiber reinforced geopolymer due to high temperature exposures.