Effect of dispersed micro-fibers on tensile behavior of uncoated carbon textile-reinforced cementitious mortar after high-temperature exposure

The mechanical and structural behavior of infrastructure and buildings under high-temperature environment is one of the major concerns in retrofit technologies. The present study aims to experimentally investigate the effectiveness of dispersed micro-fibers on the tensile behavior of uncoated carbon textile-reinforced mortar (TRM) after exposure to high temperatures. The main experimental parameters include the micro-fiber type, fiber volume fraction, and high-temperature level. Micro-steel fibers and amorphous metallic fibers with lengths of 13 and 15 mm, respectively, were utilized in this study to ameliorate the cementitious mortar matrix with a volume fraction in the range of (0.4–0.8) %. Three investigated temperature levels were 25 °C (ambient condition), 200 °C, and 400 °C. The tensile tests were carried out based on RILEM TC 232-TDT after specimens cooled down to ambient temperature. The experimental results indicate that the inclusion of micro-steel and amorphous metallic fibers within the mortar matrix significantly ameliorated the tensile characteristics of TRM specimens at both ambient and high temperatures. In addition, micro-amorphous metallic fibers exhibited significant advantages compared with steel fibers to improve the crack stress after exposure to 200 °C. Based on the experimental results and material characteristics, this study proposed an analytical model to predict the tensile strength after exposure to high temperatures and the idealized tensile stress-strain curves at the ambient temperature, of TRM composites incorporating dispersed micro-fibers, and the model prediction showed a good correlation with the experimental results.