Durability and accelerated ageing testing of CFRP repair systems

ABSTRACT: Near surface mounted (NSM) FRP reinforcement has recently emerged as a promising technology for strengthening concrete structures in both flexure and shear. This technique has numerous potential advantages over externally bonded FRP strengthening systems and is able to more fully exploit the strength of FRP materials because of generally superior anchorage performance. Research to date has focused primarily on overall member behavior and/or the various parameters that affect the bond of either rectangular NSM strips or round NSM bars. Little information is available on the cold-regions durability of these systems, in particular with respect to their performance at low temperatures as might be experienced in bridge parking, and some industrial applications. Available research studying the performance of externally bonded FRP strengthening systems at low temperatures has shown few negative effects Nevertheless, with the increased volumes of adhesive required for NSM applications and the associated differential thermal expansion between the FRP, adhesive, and substrate concrete damage due to differential thermal expansion and epoxy embrittlement at low temperature could become important. This paper presents the results of an experimental program investigating the low temperature flexural performance of NSM carbon/vinylester FRP tape strengthened concrete slabs. The effects of adhesive type (cementitious or epoxy) and groove width are discussed at both room (21°C) and low (-26°C) temperature. The results show no discernable negative impacts on the performance of any of the strengthened members at low temperature