Retrofitting of Reinforced Concrete Beams with CARDIFRC

A new retrofitting technique based on a material compatible with concrete is currently under development at Cardiff University. It overcomes some of the problems associated with the current techniques based on externally bonded steel plates and FRP (fiber-reinforced polymer) laminates which are due to the mismatch of their tensile strength and stiffness with that of the concrete structure being retrofitted. This paper will describe briefly the technology necessary for preparing high-performance fiber-reinforced concrete mixes (HPFRCC), designated CARDIFRC. They are characterized by high tensile/flexural strength and high energy-absorption capacity (i.e., ductility). The special characteristics of CARDIFRC make them particularly suitable for repair, remedial, and upgrading activities (i.e., retrofitting) of existing concrete structures. The promising results of several studies using CARDIFRC for retrofitting damaged concrete flexural members will be presented. It will be shown that damaged reinforced concrete beams can be successfully strengthened and rehabilitated in a variety of different retrofit configurations using precast CARDIFRC strips adhesively bonded to the prepared surfaces of the damaged beams. To predict the moment resistance and load-deflection response of the beams retrofitted in this manner an analytical model will be introduced, and the results of the computations will be compared with the test results to evaluate the accuracy of the model.