Investigating the effects of employing recycled carpet fibers and micro-silica on the mechanical properties of concrete under elevated temperatures

The present research explores the behavioral characteristics of concrete produced with recycled carpet fibers and micro-silica additives, examined under both room temperature (25 °C) and high-temperature conditions (200 °C and 600 °C). Carpet fibers were incorporated into the mixtures at volume ratios of 0.5%, 0.75%, and 1%, and experimental investigations were carried out to determine the compressive strength, tensile resistance, and elastic modulus of the re-sulting composites. Unlike previous studies that examined fibers or micro-silica separately and primarily under ambient conditions, this work is original in combining recycled carpet fibers with micro-silica and assessing their synergistic effects under elevated temperatures (200 °C and 600 °C) through laboratory-scale testing of cubes, cylinders, and beams. The study highlights the combined use of recycled carpet fibers and micro-silica to enhance mechanical strength while preserving performance under thermal exposure, an aspect overlooked in earlier research. This dual focus enhances understanding of both mechanical behavior and sustainability, offering practical guidelines for structural applications. The results show that incorporating 0.5% carpet fibers with 10% micro-silica achieved the highest performance, improving CS by 21% compared with the reference mix. Higher fiber contents (0.75% and 1%) reduced performance due to poor fiber dispersion and bonding. At elevated temperatures, both compressive and tensile strength decreased, with the tensile strength exhibiting a more pronounced reduction due to fiber degradation. Furthermore, using 0.5% recycled carpet fibers promotes sustainability by diverting non-biodegradable waste from landfills and reducing the need for virgin materials, thereby lowering the environmental footprint of concrete production.