Influence of graded glass fibres on strain hardening and strain softening behaviour of CGGF under uniaxial stress

Abstract

In this investigation, four different lengths of glass fibres were blended together in a graded glass fibre form – that is, short graded glass fibre (SGGF: 3 + 6 mm), long graded glass fibre (LGGF: 12 + 20 mm) and combined graded glass fibre (CGGF: 3 + 6 + 12 + 20 mm) – and added to the concrete. The uniaxial tension and compression behaviour of M50 grade concrete with graded glass fibres at three different volume fractions – that is, 0·3, 0·4 and 0·5% – for five different fibre volume combinations were studied. It was observed that adding SGGF to the concrete results in higher peak strength and adding LGGF to the concrete resulted in higher post-peak deformation. The best performance was exhibited by the combination of SGGF  and  LGGF (CGGF) for the same volume fraction of fibres, and this was attributed to the grading of the different fibre lengths, which can control the different scales of cracking and thus contribute to the increase in pre-peak strength and post-peak deformations. Finally, from this study it was concluded that the strain softening behaviour in compression was influenced by the strain hardening behaviour in the tension of graded-glass-fibre-reinforced concrete.