Repair of fire-damaged RC slabs with basalt fabric-reinforced shotcrete

In this paper, an innovative basalt fabric-reinforced shotcrete system is proposed for the flexural strengthening of fire-damaged RC slabs for the first time. An extensive experimental program was conducted to validate this new fabric-reinforced cementitious matrix system. Parameters investigated in the tests included the duration of heating for the fire-damaged RC slabs, the types of the cementitious matrix (strain-hardening engineered cementitious composites (ECC) versus polymer-modified mortar (PMM)) and the layers of basalt fabrics that are used for the strengthening systems. A total of nine one-way slabs were constructed and tested in this paper. One slab served as the control specimen and was tested at ambient temperature, while the other eight slabs were initially exposed to the furnace fire following the ISO 834 standard temperature-time curve. After fire exposure, five slabs were strengthened using two or three layers of the strengthening systems. Test results indicated that the flexural capacity of the fire-damaged RC slabs strengthened with the basalt fabric-reinforced shotcrete systems was increased by 68.9-193.4% compared to their un-strengthened fire-damaged counterparts. The use of ECC as a cementitious matrix was found to be an attractive solution as the slabs strengthened using ECC achieved better results in terms of the cracking control and ultimate load, ductility performance as well as energy dissipation capacity.