Complete stress-strain curves for pine needle fibre reinforced concrete under compression

To reduce the high consumption of natural resources by civil construction, in recent years, there are more and more re-searches on using natural biomass to replace coarse and fine natural aggregates. Masson pine needle fibre (MPNF) is an im-portant raw material for environment-friendly and cost-effective. In this paper, the surface of pine needles was directly modified by boiling water, 2% dilute alkali and soaking in water. Each set of experimental samples containing volume contents of MNPF with 30 mm length ranging from 0% to 2% by concrete volume were prepared. The stress-strain behaviour and the mechanical properties of pine needle fibre reinforced concrete (PNFRC) under uniaxial compression are studied. The result of this paper shows that the addition of pine needle fibre changed fracture process and improved the mechanical properties compare to that of plain concrete. Compared the fitting curve of the proposed equations and experimental date, it can be concluded that using 0.5% and 1% of dilute alkali-treated and boiling water-treated MPNF adding in the concrete, consents to obtain a composite with optimum mechanical properties, and the proposed model in this paper could express the stress-strain curves of PNFRC.