Thermal and Mechanical Characterizations of Nanomaterial-Modified Adhesive Used in Bonding CFRP to Concrete

Nanomaterials are increasingly being used to modify adhesives used in aerospace and materials applications. Improvements in thermal and mechanical properties have been found by incorporation of small amounts of nanosize materials in to such adhesives. However, the introduction of nanomaterials to adhesives used in civil engineering applications is still a new approach which needs to be explored, especially in retrofitting of structures. This paper presents part of an ongoing research to address the effect of adding nanomaterials to modify a thermosetting adhesive used for bonding carbon fibre reinforced polymer (CFRP) composites to concrete members. Vapour grown carbon fiber (VGCF) was chosen to modify the adhesive. Different concentrations of carbon nanofibres PR-24 XT-LHT were adopted for modification. The effect of nanomaterials inclusion on the glass transition temperature (T-g) of the adhesives was investigated using the dynamic mechanical thermal analysis (DMTA) technique. It was found that a slight reduction occurred in the T-g by adding 0.5 to 2 wt% of VGCF to the adhesive. A very slight improvement in the bond loss temperature was observed with the addition of VGCF to the adhesive using adhesion (pull-off) tests and single-lap shear tests at elevated temperatures.