The fracture energy and mechanical properties of high-strength concrete containing polyolefin macro-fibres

Abstract

In this study, the mechanical properties and fracture energy of high strength fibre reinforced concrete (HSFRC) have been investigated. For this purpose, eight mix compositions have been made in two water-to-binder (W/B) ratios of 0.32 and 0.37. The quantity of coarse and fine aggregates in the two W/B ratios were not the same. The polyolefin macro-fibres were used at three different fibre volume fractions of 0.2, 0.4 and 0.6%. The compressive strength, flexural strength, fracture energy, capillary water absorption, electrical resistivity and ultrasonic pulse velocity tests of concrete mixes were studied. The results showed that polyolefin macro-fibres had negligible effect on the compressive strength. However, the use of polyolefin macro-fibres improved the flexural strength of high-strength concrete. The highest improvement of flexural strength was obtained in the volume fraction of 0.4% at the W/B ratio of 0.32, which improved by 22.1% in comparison to the control mix. Moreover, the fracture energy of high-strength concrete highly depended on the amount of macro-fibres. For instance, the use of 0.2, 0.4 and 0.6% macro-fibres has led to the improvement of fracture energy by 133, 228 and 190% for mixes with W/B ratio of 0.32, respectively. Furthermore, by increasing the amount of fibres, the capillary water absorption coefficient of concrete enhanced; therefore, its water penetration increased.