Development of a new nano modified cement based adhesive for FRP strengthened RC members

Abstract

There is currently a high demand in the construction industry for high-strength and durable cement-based adhesives (CBAs) for use in a variety of applications such as ground anchors, ground improvement, concrete repair or as a substitute for epoxy resins to bond carbon fiber reinforced polymers (CFRPs) to concrete structures where increased fire performance is required. Limited research has been conducted on the use of nano-materials such as graphene oxide (GO), graphene nanoplatelets (GNPs) and nano silica (NS) to improve the mechanical properties and durability of CBA. This paper presents a new mix design comprising ordinary portland cement, GNP, GO and NS to improve the strength and durability of CBA. Furthermore, the paper presents bond-slip measurements between carbon fibre reinforced polymer (CFRP) and CBA embedded in concrete prisms. Single lap shear prisms are tested using different CBA mixes and structural epoxy to assess the bond for near surface-mounted (NSM) strengthened structures. The results show improvement in the compression and flexural strength of the CBA by up to 46% and 57% respectively by using NS and GO at low concentrations. The durability tests indicate that the modified CBA has 61% lower chloride penetration than standard CBA due to reduced porosity. The pull-out tests were conducted of FRP-to-concrete joints using the CBA materials and results of GNP-reinforced CBA show an improvement of 27% and 73% for CFRP laminate and textile, respectively.