Enhancement of concrete performance and sustainability through incorporation of diverse waste carpet fibres
Nayanatara Gamage, Chamila Gunasekara, David W. Law, Shadi Houshyar, Sujeeva Setunge, Andrzej Ćwirzeń
Abstract
Carpet fibres have demonstrated the potential to mitigate early-age cracking and improve tensile properties in concrete. However, a detailed analysis of the varied types of standard carpet fibres in reinforced concrete has been lacking. This study aims to bridge this gap by investigating the performance of concrete reinforced with widely used waste carpet fibres, namely Nylon, Polypropylene, Polytrimethylene terephthalate, and Polyester. The study employs fibres at 0.3 % and 0.5 % volume fractions with a 12 mm length. The research examines mechanical properties, shrinkage and cracking behaviour, pore structure, microstructure, and the ITZ. Results show that 0.3 % fibre volume yielded optimal performance based on GRA analysis. All fibre types reduced shrinkage compared to the control with no fibres. Nylon T1 at 0.3 % achieved a 22.3 % reduction at 90 days. Furthermore, fibre inclusion enhanced flexural and splitting tensile strengths up to 12 % and 39 % respectively due to fibre bridging, pore refinement, and reduced porosity. Notably, individual fibre mechanical properties influenced concrete performance significantly. Hydrophilic fibres exhibited a thinner 10 µm ITZ compared to 15 µm for hydrophobic fibres, contributing to denser interfacial regions and improved bonding. This study demonstrates the potential of carpet fibre-reinforced concrete as a sustainable solution, offering enhanced mechanical properties, shrinkage mitigation, and effective utilization of carpet waste, addressing critical issues in construction and waste management sectors. • PTT T1 (0.5 %) had highest flexural strength, 11.8 % higher at 28 days, than control. • Compressive strength and shrinkage reduction were optimum with 0.3 % fibre volume. • Nylon T1 fibres (0.3 %) reduced shrinkage by 22.3 % at 90 days compared to the control. • Nylon T1(0.3 %) had the lowest porosity, 81.12 % lower than the control at 28 days. • Hydrophobic fibres had an ITZ of 15 µm, while hydrophilic fibres had an ITZ of 10 µm.