Fibre Modification for Concrete Reinforcement using a Novel Atmospheric Microwave Induced Plasma Torch (MIPT)

Abstract

This research investigates the design of a novel microwave induced plasma torch for the surface modification of non-corrosive fibres. The system was developed to reduce the equipment cost, and production time needed in the conventional plasma treatment. To generate a consistent and low-cost microwave plasma jet at atmospheric pressure, a waveguide-based applicator at 5.8GHz was used. The system uses a microwave signal generator connected to a traveling wave tube to provide the required power. The applicator consists of a nozzle section and a tuning section to decrease the reflected power. Argon gas flows through the copper nozzle, and the high electrical field due to the microwave power, between the gas nozzle and an aperture in the waveguide, causes the gas to become a plasma that flows as a jet through the aperture and into the atmosphere. The effect of plasma treatment on surface characterisation of fibres was performed using contact angle measurement, scanning electron microscopy and atomic force microscope and the results are presented and analysed. Thus, the optimised plasma condition for each separate fibre is utilised. Fibres treated with optimised plasma condition were further used in investigating the fibre-matrix interfacial properties. Furthermore, the effect of the plasma treatment on the flexural behaviour of cementitious composites was investigated using three-point bending. The results show some improvement in the fibre surface properties, so there is a potential of using the developed plasma system in the production of construction composites.