30 / 2022-03-13 05:45:06

Fire Spalling Behavior of RC Beams Repaired with Polymer Cement Mortar under Fire condition

RC beam, polymer cement mortar, nylon fiber, fire spalling

Polymer cement mortar (PCM) is used for the cross-sectional repair of RC structures. PCM is a cement mortar using polymers to improve adhesion on the base concrete. On the other hand, recent papers reported PCM has the risk of spalling under high temperatures.　 In our group, the fire spalling behavior of PCM using ring restrained specimen was evaluated. However, it is unclear fire spalling behavior of RC beam repaired with PCM under fire. In this study, we conducted heating tests of RC beam repaired with PCM. The size of the RC beam was 1500 mm × 100 mm × 150 mm (length × breadth × height). Two rebar of D13 were placed as the main bar at an effective height of 125 mm. Size of stirrup is 110×70㎜ using rebar of D6 and placement spacing was 100mm. The polymer cement ratio (P/C) of the PCM used for the repair was set at 10%. It evaluated the spalling behavior on PCM with the presence or absence of nylon fiber. The mixing ratio of Nylon fiber was 0.5%vol. Repair thickness of PCM was 50 mm. Heating condition used RABT30 heating curve. As a result, spalling depth was 38mm in the case of RC beam repaired with PCM. On the other hand, spalling depth was 9mm in the case of RC beam repaired by PCM with nylon fiber. The Fire spalling depth of PCM with nylon is smaller than PCM without nylon fiber.