Experimental Study on CFRP Strengthened Continuous Reinforced Concrete Slab after Fire

This paper presents results from experimental studies on the flexural capacity mechanical properties of a continuous reinforced concrete (RC) slab with and without carbon fiber reinforced polymer (CFRP) sheets strengthened. Fire test and flexural capacity test were carried out on one continuous RC slab. Heating curve included heating stage and cooling stage. One span of continuous RC slab was strengthened with CFRP sheets at sagging moment region and hogging moment region. The results showed that the fire exposure surface of RC slab was easy to concrete spalling. The temperature variation of concrete obviously lagged behind the phenomenon. When the furnace temperature was decreasing, the temperature of concrete of the slab was still rising. Compared maximum temperatures within 120 minutes with the temperature of end heating at the same measuring point, the farther away from the fire exposure surface, the greater the temperature increased. And the time of maximum temperatures was also increased with the distance increase of from the fire exposure surface. The surface should be repaired before strengthened with CFRP sheets. CFRP sheets strengthening improved the flexural bearing capacity and stiffness of the fire-damaged slab, however, reduced the ductility of the fire-damaged slab. CFRP sheets could develop their ability in strengthening fire damaged RC slabs on condition that surface processing of fire damaged concrete.