Development of a Novel Coating for GFRP bars for Enhancing the Fire Resistance and Bond strength

Project: Research

Project Details


A large number of reinforced concrete structures and infrastructures located along the coastlines of the Arabian Gulf and the red sea as well as in desert areas in the eastern region, suffer from severe problems associated with the corrosion of reinforcing steel. Due to the prevailing harsh environment in the region, corrosion of steel reinforcement in reinforced concrete structures takes place at a rapid pace diminishing their service life. Corrosion of steel reinforcing bars is a widespread phenomenon that leads to cracking, delamination, and spalling of concrete cover, with a substantial steel section loss, requiring huge expenditures for repair and rehabilitation. There is a growing need to combat the deterioration problems associated with corrosion of reinforcing steels in the concrete structures due to the high cost of maintenance and increase the service life of reinforced concrete structures. Glass fiber reinforced polymer (GFRP) is a non-metallic composite fabricated using a matrix of polymer material (polyester, vinyl ester, or epoxy) reinforced by high-strength glass fibers. The corrosion resistance of GFRP makes it an attractive option in regions characterized by a harsh environment. GFRP bars in concrete structural members have several benefits compared to conventional black steel bars, including high strength to weight ratio, lightweight, easy and fast installation, electromagnetic neutrality, high fatigue endurance, and lower transportation and installation costs. The low unit weight of GFRP and matching thermal and stiffness characteristics to concrete makes GFRP concrete a unique composite material. However, concrete structures reinforced with GFRP bars are commonly known to have lower fire resistance than equivalent conventional steel-reinforced concrete structures, which is one of the major obstacles against using GFRP bars, particularly in industrial facilities. Moreover, relatively lower bond strength compared to steel bars, low tensile creep rupture, low elastic modulus, and low shear strength are some of the barriers to adoption in structural members. In addition, the low fire resistance of the GFRP bars due to the lower glass transition temperature of the resin is another major drawback for GFRP bars. Several attempts have been made to enhance the bond resistance by various forms of sand coating, altering the geometry by adding ribs on the surface of the bars or by helical wrappings. These alterations have resulted in significant enhancement of the bond strength, but further enhancement in bond strength is needed. The second issue of fire resistance of the GFRP bars is still elusive, and attempts have been made to enhance the fire resistance by applying coatings. The coatings, in general, result in a decrease in bond strength. The main focus of this proposed research is to develop a novel coating technology that could accomplish the dual purpose of increasing the fire resistance of GFRP bars as well as enhancing their bond strength with concrete. Coatings will be investigated using organic coatings such as ammonium polyphosphate, acrylic/vinyl/polyvinyl acetate polyphenylene sulfide, or inorganics such as tannic acid-functionalized graphene and polysilicon. Hybrid of these materials will possibly be investigated. This interdisciplinary research, if successful, will promote and expand the application of GFRP bars in concrete structural elements and components as part of key infrastructures and industrial facilities. The developed coating technology will combat the high cost of repair and rehabilitation of steel-reinforced concrete structures. The outcomes of the proposed study will have socio, economic and environmental benefits.
Effective start/end date1/07/2131/12/22


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