| Summary: | Fiber-reinforced polymer (FRP), a polymer matrix composite material, has been established as one of the possible techniques to strengthen concrete beams in flexure and shear. It has demonstrated good performance in retrofitting and repairing deteriorated reinforced concrete (RC) structures. However, FRP has the tendency to lose bond with the substrate due to the low glass transition (Tg) of its matrix polymer. Currently, very little information regarding to fire endurance of FRP-strengthened RC square column and the performance for insulated FRP-strengthened RC has also not been clearly addressed. This paper presents a full-scale fire resistance experiment on unstrengthened (bare) and Carbon Fiber-Reinforced Plastic (CFRP) strengthened RC with and without insulator column specimens. Ultra-high-performance fiber-reinforced cement composite (UHPFRCC) material composed of high alumina cement (HAC) and ground granulated blast slag (GGBS) in equal proportion was used to insulate the bare RC column and the column strengthened with CFRP. Two types of UHPFRCC cladding skin with one contained only polypropylene (PP) and another one with hybrid containing PP and basalt fibers were adopted. A comparison was made between the fire endurance characteristic between strengthened and unstrengthened; those with UHPFRCC insulated and those without insulator. It was found that CFRP-strengthened columns failed 15 minutes later than the unstrengthened column. In a nutshell, the developed UHPFRCC made of equal proportion of HAC, GGBS containing only 1% PP fibers improved the fire endurance of unstrengthened and CFRP-strengthened RC column significantly. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
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