Rehabilitation of Existing Structures Using Carbon Fiber-Reinforced Polymer (CFRP) Jacketing

Abstract

While new reinforced concrete (RC) structures are being constructed at an incredible pacearound the globe, existi ng structures seek periodic maintenance and damaged ones need necessary rehabilitation. The deterioration of existi ng structures might occur due to ageing of materials, environmental corrosion of embedded steel, inadequate quality of concrete, poor operations and mai ntenance, design deficiency, changes in use or imposed loadi ng, fire damage, malpractices duri ng construction,and natural calamities. The damaged structural members may be strengthened i n flexure withthe use of CarbonFiber-Rei nforced Polymer (CFRP) bonded to their tension zone usi ng suitable epoxy as a common adhesive. In comparison to traditional rehabilitation techniques, for instance externally bonded steel plates, steel jackets, concrete jackets or external post-tensioning, CFRP wrapping has proved to be far more advantageous. The increasi ng popularity of CFRP can be ascribed to its light weight, corrosion resistance, high tensi le strength, easy installation and aesthetically pleasing outlook. Despite its unprecedented structural viability,its high initial cost and lack of conversance of contractors and consultantsof construction industry of Pakistan with this technique has put it behi nd other rehabilitation techniques. With the i ntent to troubleshoot the aforementionedobstacles toward its choice as a rehabilitation technique particularly in the construction industry of Pakistan, an experimental study is carried out to economize the quantitati ve use of CFRP for rehabilitation of RC beams. The experimental program involves testi ng ofthreefull-scale beams, having 7.5”x10.5” cross-section and 7.5’ clear span, underfour-point bending. A comparative analysis between beams fully and selectively jacketed with CFRP in U-shape configuration has been drawn. To simulate degradation of structural members in real-time, two beams are first loaded to 65% of ultimate strength, unloaded, and then 5wrapped before testing.In addition, a technical survey is carried out to determine how conversant, and confident are the contractors and consultants of construction industry of Pakistan with CFRP jacketing as a potential technique for rehabilitation of existing structures. The experimental results i ndicate that CFRP jacketing i ncreases the strength of degraded structural member significantly. Furthermore, the ultimate load recorded for fully jacketed beam is almost same as that for selecti vely jacketed beam. The technical survey shows that the contractors and consultants i n Pakistan are not confident in adopting this technique as an alternate solution.