Efficiency of CFRP Strengthening Measures for Reinforced Concrete Structural Members Using Toughened Epoxies

Abstract

This paper aims to investigate the interface efficiency of Carbon Fiber Reinforced Polymers (CFRP) adhesively bonded on concrete, a commonly used retrofitting measure applied for enhancing the deformability and strength of decaying structures or existing ones with low capacity. The efficiency quantification is expressed with the Interface Capacity Index (IC). The index correlates the thickness and strength of each layer of the strengthening system and accounts for the transferred loads (ICL) and the strain distribution that causes the failure propagation on the concrete substrate (ICfp). The investigation focuses on different CFRP strengthening schemes (laminated fabrics, prefabricated plates, Near Surface Mounted bars-NSM) applied to concrete substrates using different adhesive layers. Two cases were studied for different levels of concrete’s integrity: (a) healthy and (b) containing corrosion products. The experimental results were used to calibrate the numerical models and to evaluate the effects of different strengthening strategies. The results show the tendency of the strengthening systems to shift the interface performance from fully elastic to non-linear. Further, the quantification of the efficiency of retrofitting can be addressed by accounting for the mechanical and geometrical properties at the interface level, representing different failure modes and integration levels.