Rate dependent behaviour of 3D printed ultra-high performance fibre-reinforced concrete under dynamic splitting tensile

Abstract

With the development of additive manufacturing, attention to 3D printing concrete construction technology has been paid. Dynamic performance is one of the important material properties of concrete. However, the rate dependent behaviour of 3D printed concrete under dynamic tension has not been explored. In this study, the dynamic splitting tensile test of the 3D printed ultra-high performance fibre reinforced concrete (3DP-UHPFRC) was performed. The dynamic splitting tensile behaviour of 3DP-UHPFRC was analysed by varying the preparation method, with or without fibre, fibre length, impact velocity and tensile direction, and the anisotropic characteristics of 3DP-UHPFRC were evaluated. The test results revealed that the failure mode of 3DP-UHPFRC exhibited ductility in the X-direction and experienced brittleness in the Y- and Z-directions. When the strain rates are the same (12 s−1), the peak stress of 3D printing specimen with 6-mm steel fibre in the X-direction is 49.038% higher than that of 3D printing specimen without steel fibre in the X-direction, while 3D printing specimen with 6-mm steel fibre in the Y-direction is only 2.350% higher than that of 3D printing specimen without steel fibre in the Y-direction. The dynamic increase factor (DIFst) of tensile strength of the 3D printed ultra-high performance concrete (3DP-UHPC) without steel fibre demonstrated insignificant anisotropy, while DIFst for 3DP-UHPFRC in the X-direction was remarkably lower than that in the Y- and Z-directions. Moreover, a dynamic tensile orthotropic constitutive model was preliminarily proposed for further study.