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 degrees C (ambient condition), 200 degrees C, and 400 degrees 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 degrees 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.