Developing Sustainable and Multifunctional Cementitious Composites by Repurposing FRP Composite Waste

Abstract

Fibre-reinforced polymer (FRP) composites are widely used across industries due to their high strength-to-weight ratio, durability, and design flexibility. However, their non-biodegradable nature and complex thermoset matrices pose significant environmental challenges, especially as waste from manufacturing and end-of-life (EoL) products accumulates. Conventional disposal methods like landfilling and incineration are unsustainable, prompting the need for circular economy-aligned recycling strategies.

This research explores sustainable repurposing of carbon and glass FRP (CFRP & GFRP) waste in cementitious composites (CCs). It presents experimental and numerical studies on incorporating mechanically and chemically recycled FRP waste, sourced from fabric offcuts and industrial components, into cementitious matrices. The effects of fibre type and content on mechanical, durability, and microstructural properties are evaluated. Advanced imaging techniques, including micro-computed tomography (micro-CT) and ultrasonic testing, are employed to characterise voids and fibre dispersion. Novel image processing filters are developed to enhance CF detection in cement matrices.

To improve fibre-matrix bonding, bio-based and electrochemical surface treatments for CFs are introduced and assessed through morphological, chemical, and mechanical analyses. Additionally, pulverised FRP waste from electrical and aerospace components is repurposed as a partial cement substitute, showing improved strength, reduced shrinkage, and denser microstructure.

The study also investigates the self-sensing capabilities of CCs incorporating recycled CFRP for structural health monitoring (SHM), particularly under chloride-induced corrosion. Results demonstrate the potential of recycled FRP in enhancing CC performance and multifunctionality, offering a sustainable alternative to traditional waste disposal and contributing to greener construction practices.