Short composite fibres for concrete disperse reinforcement

Abstract

Short composite fibres are a relatively new product for concrete disperse reinforcement. In this experimental research, 14 different composite fibres were developed and single fibre pull-out micromechanics was investigated. Three main groups of composite fibre were—composite glass fibres (GF), composite carbon fibres (CF) and hybrid fibres (HF). Composite fibre manufacturing consisted of glass, carbon or combined fibre filament preparation, impregnation with epoxy resin, epoxy curing, quality control and cutting in short discrete macro- fibres. All three composite fibre groups were manufactured with straight, uneven and undulated geometries. Fibre surface finish was smooth and rough. Uneven fibre geometry was achieved by not aligning all fibre filaments in fibre tow. Undulated geometry was a result of interlaced fibres. The rough fibre outer surface finish was achieved by adding an extra layer of epoxy resin containing fine quartz grains. All macro-fibres were cut in 50 mm length. Single fibre pull-out samples with a pre-defined crack between two concrete parts were prepared to investigate fibre pull-out behaviour. Fibre pull-out laws were obtained and analysed. Composite fibre improvement geometry and surface with roughening outer surface made a huge impact on fibre pull-out resistance.