Experimental study on reinforced concrete beams strengthened with Basalt and Carbon Textile Reinforced mortars at elevated temperatures

Reinforced concrete members strengthened with Fibre-Reinforced Polymer will suffer degradation when exposed to elevated temperatures or fire without an external insulation. Textile Reinforced Mortars (TRMs) can alleviate these problems posed by Fibre Reinforced Polymer epoxies at elevated temperatures. The present study deals with the thermo-mechanical behaviour of reinforced concrete beams strengthened with Textile Reinforced Mortar at elevated temperatures. Reinforced concrete beams were strengthened with Basalt and Carbon textiles and tested while the specimens were maintained in hot conditions. Carbon and Basalt TRMs were applied as one-layer and one- and three-layer, respectively. All the test specimens were heated to 200 °C, 400 °C, 600 °C, and 800 °C, followed by mechanical loading to evaluate their flexural behaviours. Strengthened members experienced common degradation of flexural strength when subjected to higher temperatures except at 400 °C. The test results revealed that Textile Reinforced Mortars can sustain temperatures up to 600 °C, but the concrete and steel underwent degradation at this temperature. At 800 °C, the Basalt textile showed signs of annealing, whereas the carbon textile oxidised from the textile reinforced mortar matrix. The study also evaluated strengthened members' thermal response and mechanical failure patterns at elevated temperatures.