Study on the performance of polyester fibers modification system for low carbon magnesium silicate-based cementitious materials

Abstract

To mitigate the environmental hazards posed by discarded plastics, polyester fibers produced from such waste have been incorporated into building composites. However, the durability of polyester fibers in cementitious environments is compromised by high alkalinity, which may lead to resource wastage. In this study, polyester fibers were embedded in magnesium silicate hydrate to develop a novel, highly reinforced material. The mechanical properties of this composite were investigated through compression tests and four-point bending test, with variations in fiber content and curing periods. Among many organic fibers, polyester fibers are more effective in improving the fracture toughness of the magnesium silicate hydrate system without reducing the compressive strength. Optimal properties were achieved with a fiber content of 1.5 %, exhibiting a compressive strength of 44.2 MPa and ultimate bending toughness reaching 5.8 MPa at 28 days. To further investigate the toughening mechanisms, the fiber-matrix interface was characterized using scanning electron microscopy, single fiber pull-out tests, alkali solution immersion, infrared Fourier transform spectroscopy, and nanoindentation tests. Bending toughness test and monofilament drawing test indicate that polyester fibers are more suitable for use in low-alkali hydration magnesium silicate systems compared to traditional portland cement gelling systems. Scanning electron microscopy and nanoindentation analyses showed that polyester fibers exhibit superior bonding properties with magnesium silicate hydrate composites and enhance their ductility. Analysis of alkali solution immersion revealed that polyester fibers are eroded in high alkaline environments, primarily due to hydrolytic degradation of ester bonds on fiber surfaces.