Carbon nanotubes as a reinforcement material for sustainable construction composites

B. Makgabutlane, N. Coville, S. Mhlanga, M. Maubane-Nkadimeng
University of the Witwatersrand,
South Africa

Keywords: carbon nanotubes, waste plastic, coal fly ash, eco-bricks, sustainability

Summary:

Carbon nanotubes (CNTs) have gained considerable attention for various applications because of their distinct inherent properties. They are characterized by high surface area, aspect ratio, thermal stability, and excellent mechanical strength. There are different synthesis approaches that have been adopted with the aim of producing CNTs of high quality, yield and that are economically viable for large application industries. In this study, a floating catalyst chemical vapour deposition (FC-CVD) method was adopted to synthesize CNTs. The FC-CVD method is facile as both the carbon source and catalyst are introduced simultaneously into the furnace and can allow continuous CNT production. Multi-walled carbon nanotubes (MWCNTs) of high quality were produced with this method and functionalized by acid reflux to enhance their processability and to ensure homogeneous dispersion in the intended construction composite (eco-bricks) application. Fly ash, which is a byproduct of coal combustion was used as the aggregate material and waste plastics as the binder in the production of the composites. MWCNTs were used as the reinforcement material for the waste-derived construction composites. The effect of MWCNT loading was studied on the mechanical properties of the composites. It was observed that the MWCNTs, due to their nano size filler-effect facilitated load transfer and reinforced the composites. This ensured the development of construction bricks with high mechanical strength and improved durability. The study aims for a more circular economy within the built environment that ensures the production of sustainable and cost-effective building materials.