Tensile properties of carbon fabric-reinforced cementitious matrix (FRCM) at high temperatures

Abstract

Despite many advantages of externally bonded FRP systems, the rapid loss of strength at high temperatures is a concern for fire scenarios. Fabric-reinforced cementitious matrix (FRCM) is deemed to perform superior at high temperatures. In this study, 84 carbon FRCM coupons were tested in tension at temperatures from 25 to 400 °C using both steady-state and transient-state test protocols. The main parameters considered in this study are the number of fabric layers and FRCM thickness, fabric orientation, target temperatures, and heating protocol. Results showed that at room temperature, the ultimate strength and cracked elastic modulus decreased by about 18% to 20% when the number of layers was increased from one to three. At 400 °C, the ultimate strength and cracked elastic modulus were reduced by up to 60 to 70% of their original values. The bidirectional FRCM specimens presented a slightly higher elastic modulus and strength than unidirectional specimens in most tests. In transient-state tests and under the same sustained load level, the failure temperature of 30 mm-thick specimens were approximately 100 °C higher than 20 mm-thick specimens. The test results showed that the carbon FRCM composites tested in this study were able to resist non-negligible tensile forces at elevated temperatures although they are significantly reduced.