Mechanical Performance of Concrete Reinforced with Textile Waste Fibers: A Systematic Review and Meta-Analysis

Textile waste is predominantly landfilled or incinerated, while the construction sector requires materials of lower embodied impact. This study reports a systematic review and meta-analysis of the mechanical performance of textile waste fiber-reinforced concrete (TWFRC), based on two decades of research retrieved from Scopus and Web of Science following the PRISMA 2020 protocol. Effect sizes were expressed as log response ratios and pooled using a DerSimonian-Laird random-effects model; heterogeneity was quantified using Cochran’s Q, I2, and τ2, with subgroup analysis by fiber category and sensitivity analysis via variance imputation. The pooled estimates indicate statistically significant improvements of 19.0% (95% CI: 9.8–28.8%) in compressive strength, 33.2% (18.0–50.2%) in split tensile strength and 34.8% (11.7–62.6%) in flexural strength relative to unreinforced controls, consistent with a crack-bridging reinforcement mechanism. Optimum fiber volume fractions cluster between 0.5% and 1.5%, and effective fiber lengths between 20 and 50 mm. Glass and recycled steel fibers produce the largest strength gains, synthetic fibers enhance ductility and crack control, natural fibers require surface treatment, and hybrid systems exhibit clear synergy. Strength retention exceeds 85% after 150–300 freeze–thaw cycles, with global warming potential reduced by approximately 10%. Standardized test protocols and extended durability programmes remain prerequisites for adoption.