Experimental study on tensile and fracture properties of continuous directional steel fibre reactive powder concrete

In this paper, an orientation method with pre-tensioning at both ends is proposed to successfully prepare continuously directional steel fibre reactive powder concrete (DSFRPC). The tensile and fracture properties are determined by splitting tensile, axial tensile and three-point notch fracture tests. The paper sets three different groups named C0, Group S and Group D, which presents non-fibre, randomly distributed fibre and directional fibre, respectively. The test results showed that: the splitting strength of Group D specimens increased quite significantly with the increase of fibre dosage. Compared to the Group S, the splitting strength of Group D was improved by 46.5%, 69.8%, and 66.1%, respectively. The specimens of C0 and Group S in the axial tensile test suffered typical single-seam brittle failure, which showed obvious strain softening characteristics. With the increase of fibre dosage, the damage mode of specimens in Group D changed from single-seam brittle damage to multi-seam ductile damage, showing better energy dissipation capacity. Under the same converted fibre dosage, the fracture energy enhancement ratios of Group D specimens were 14.7, 18.9 and 19.55, respectively. At a lower water-cement ratio, the toughening effect of continuous directional steel fibre specimens is more obvious. The toughening effect of the reactive powder concrete (RPC) of with continuous directional steel fibre is mainly reflected in the directional distribution of steel fibre produced by the interfacial adhesion and friction caused by the increase in energy dissipation, as well as the maintenance of a stronger grip between the "dispersed rebar" and the matrix. Based on current study, the future research should be focused on a wider range of materials, structural design, and environmental conditions to verify the effectiveness and reliability of DSFRPC in various applications.