Tomographic microstructural investigation of waste fishing net-reinforced high performance cementitious composites

Abstract

Recycling waste fishing nets (WFNs) is essential to reduce plastic litter production in the ocean. This study proposed the application of WFNs as fiber reinforcement for developing high performance cementitious composites (HPCC). Micro-computed tomography (micro-CT) and optimized image processing were utilized to characterize the microstructure of the WFN-reinforced HPCC. WFN-HPCC specimens were prepared with two types of WFN fiber (ground waste fishing net [GN] and ground waste rope [GR]) and different fiber contents (1, 2, and 3%), and morphological and statistical analyses were performed to evaluate the microstructure of the WFN-HPCC quantitatively—particularly focusing on three dimensional (3D) properties of fiber dispersion, fiber orientation, and pore structure. Furthermore, the mechanical properties of WFN-HPCC were surveyed to investigate the impact of the microstructural characteristics on these properties. The degree of 3D dispersion of WFN fibers increased with increased fiber content, and the fiber orientation was significantly different depending on the fiber type and content. The degree of fiber orientation in horizontal direction was highest in WFN-HPCC with 1% of the GN fibers. Its average polar angle was 72.07° in which fiber clumping was not observed. It was confirmed that the WFN fibers allowed the formation of more pores with diameters ranging from 30 to 700 μm. Along with the observation that the micro-tomographically detected porosity (i.e., quantitatively measured pore via micro-tomography) played a decisive role in the compressive strength of the WFN-HPCC, the addition of the WFN fibers, especially the GN fibers, effectively enhanced the flexural strength of HPCC up to 19.7%.