Mechanical performance of aged cement-based matrices reinforced with recycled aramid textile nonwoven fabric: comparison with other FRCMs

Utilizing recycled fibers as reinforcement in cement-based matrices is an effective means of promoting waste recycling and adopting a circular economy approach in the construction industry. Within this framework, the recycling and potential reutilization of textile residues can improve the pre- and post-cracking performance of cement-based matrices intended for building components with up to intermediate structural responsibilities (i.e., panels and cladding elements for buildings). This research is focused on the mechanical and durability -through forced aging of dry-wet and freeze-thaw cycles- experimental characterization of laminated fabric-reinforced cementitious matrices (FRCMs) containing 4 and 6 nonwoven fabric layers obtained from end-of-life fire-protecting t-shirts. For this purpose, both direct and flexural tensile tests were conducted to characterize the mechanical performance of the composite. The tests on the 6-fabric layers produced panels with Portland Cement (PC) matrix, after 28-day of curing, led to average values of the maximum tensile strength of 3.7¿MPa with associated toughness index superior to 25¿kJ/m2, and mean modulus of rupture of 11.6¿MPa with a fracture energy index of 4.3¿kJ/m2. After dry-wet accelerated aging, the post-cracking performance of the developed composites decreased (on average, 40% in toughness and 11% in strength) due to fiber embrittlement. To better understand the performance of aged composites, shredded fibers recovered from protective clothing (mainly consisting of meta-aramid fibers) were immersed in the binary matrix. Accordingly, the mechanical properties of the fibers after 5 and 10 cycles of dry-wet aging were studied. Based on the results, replacing partially PC by silica fume (between 30% and 50%) was seen as a sustainable alternative to improve the performance of the aged fibers by more than 10%.
The authors express their gratitude to the Agencia Estatal de Investigación, Spanish Ministry of Economy, Industry, and Competitiveness (Government of Spain) for the financial support received under the scope of the project RECYBUILDMAT (PID2019-108067RB-I00/AEI/10.13039/501100011033). Also, they acknowledge the funding of the research group TECTEX (2021 SGR 01056) from the Department de Recerca i Universitats de la Generalitat de Catalunya. The first author acknowledges the Banco Santander for the Research Scholarships (Postdoc-UPC 2022 Grant).
Peer Reviewed
Postprint (published version)