Utilization of recycled post consumer carpet waste fibers as reinforcement in lightweight cementitious composites

Purpose – A large amount of post-consumer carpet waste is discarded into landfills. The need to recycle this waste is increasing due to the lack of available landfill spaces in many parts of the world, environmental concerns, and resource conservation. The purpose of this paper is to explore the use of this waste for a low-cost, high-volume application. Design/methodology/approach – Fibers from carpet waste have been successfully used as reinforcement in concrete, typically at 0.1-1 per cent volume fraction (fractions by weight are even lower), for enhanced toughness. In this study, lightweight cementitious composites were fabricated that were reinforced with recycled carpet fibers at up to 20 per cent fiber to cement weight ratios. Flexural, toughness, and impact properties of the lightweight cementitious composites were characterized. Findings – The density of the composites decreases with the increase of fiber content. In the three-point bending test, lightweight cementitious composites exhibited a ductile behavior, and the flexural strength increases with the density of the composites. The energy absorption measured by the drop weight impact test was not very sensitive to the material parameters due to the total absorption of the impact energy by the specimens. Originality/value – The density of the lightweight composites ranges from 0.7 to 1.0 g/cm, which was about 30-40 per cent of the density of typical concrete. Besides being moisture and termite resistant, the lightweight composites were very tough and could be cut and fastened with ordinary tools and nails. The lightweight composites are suitable for applications such as underlayment and wall panels for buildings, as well as for outdoor structures.