Recycling waste Nix particles for ultra-high-performance concrete: A practical way towards the sustainability

Abstract

Research on Ultra-High Performance Concrete (UHPC) has demonstrated the feasibility of utilizing various types of industrial and agricultural waste to partially substitute cement or aggregates. Researchers have focused on using waste materials as mineral admixtures to substitute cement in UHPC. However, sand, the main ingredient, constitutes a significant proportion in UHPC, i.e. about 50% of the mass of concrete, thus the use of sand with a high volume can adversely affect natural resources and increase costs. This paper investigates the possibility of using Nix particle waste from ship cleaning to partially or completely substitute quartz sand in UHPC. Experimental results show that Nix particle waste has been cleaned with an average particle size of about 300 µm can be used to produce UHPC with high flowability, compressive strength above 120 MPa,  and high chloride ion penetration resistance. Life cycle assessment of concrete mixes reveal that using Nix particles to substitute sand improves the environmental performance of concrete, as shown by a reduction in all six environmental impact assessment indicators. Although the reduction level is not large, only ranging from 0.95 to 6.44% depending on each indicator, it brings socio-economic benefits thanks to utilizing waste, reducing waste treatment activities, and resource efficiency as uses natural sand in large quantities.