Fire spalling behavior of prestressed concrete beam with natural fiber

Prestressed concrete (PC) structures have the advantage of resisting tensile stress and prevent cracking because of their initial compressive stress. Thus, it contributes to the large-scale concrete structures. However, PC structures are more prone to fire spalling compared to reinforced concrete (RC) structures because of the prestressing force introduced in PC beams. Recent studies reported two major theories of fire spalling: thermal stress theory, vapor pressure theory, and their combination. Recent studies reported reducing fire spalling of concrete using synthetic fibers, such as PP fibers. On the other hand, our research group investigated the prevention of fire spalling using natural jute fibers for High strength concrete. However, the effect of jute fibers on the suppression of fire spalling in PC beams has not been reported. In this study, the fire spalling behaviour and load-displacement relationships were evaluated by bending loading tests on jute fiber impregnated PC beam specimens with a heated compression zone. Additionally, initial stiffness and ultimate bearing capacity were evaluated when the heated region was repaired with high performance fiber reinforced cementitious composite (HPFRCC). The results showed that the PC specimens with jute fiber showed an advantage in fire spalling resistance than those without Jute fiber. The load-displacement relationship of the PC specimens heated in the compression region showed that the initial stiffness and ultimate bearing capacity were significantly lower than those of the specimens without heating. Furthermore, the initial stiffness and ultimate bearing capacity of the specimens with 50 mm of HPFRCC repair in the damaged area after compression zone heating were found to be improved.