Bond characteristics of CFRP strengthened concrete members bonded using Modified Engineered Cementitious Composite

Abstract

This study focuses on the development of an insulating cementitious adhesive for bonding Carbon Fibre Reinforced Polymer (CFRP) fabrics to a concrete surface. The epoxy adhesive which is the generally used adhesive for CFRP shows a low thermal performance. As a potential solution, Engineered Cementitious Composite (ECC) mortar was modified as a cementitious adhesive with improved thermal insulation. The ECC adhesive was developed using locally available class F fly ash, silica sand and Polyethylene terephthalate (PET) fibres other than the generally used cement and water (PET-ECC). The selected mix proportion for PET-ECC achieved a low thermal conductivity of 0.145–0.180 W/mK which limited the heat transfer through the adhesive layer. The effective bond length of the developed PET-ECC adhesive was 125 mm and the corresponding bond strength was 224.9 MPa. The respective bond strength was further enhanced up to 570.28 MPa by sticking river sand on top of CFRP fabric using epoxy adhesive before bonding it to the concrete surface using the PET-ECC adhesive. The use of PET-ECC as the bonding agent to strengthen compression members with CFRP confinement yielded an average strength enhancement of 34%.