Dynamic tensile behaviour of fibre reinforced concrete with spiral fibres

This paper performs drop-weight splitting tests to study the dynamic tensile properties of fibre reinforced concrete (FRC) materials with different steel fibres. A renovated splitting tensile testing method was developed to ensure a more qualified experimental process. The splitting tensile impact tests were conducted with an instrumented drop-weight impact system consisting of a hard steel drop weight, a fast-response load cell, a high-speed video camera and a high-frequency data acquisition system. The quasi-static compressive and splitting tests were also conducted to obtain the static properties of the FRC materials. The commonly used hooked-end steel fibre and a new spiral shaped steel fibre were tested in this study. The high-speed video camera was used to capture the detailed failure process, deformation and cracking process of the tested specimens. Average strain rates and the cracking extension displacement and velocity under impact loading were estimated by analysing the recorded high-speed images. The strains were also measured by the strain gages on the specimen surface. The dynamic stress–strain and stress–COD (cracking opening displacement) relations, the rate sensitivity of tensile strength and the corresponding energy absorption capacity of plain concrete and FRC with different fibres were obtained, compared and discussed. The advantage and effectiveness of the new spiral fibre in increasing the performance of FRC under dynamic tensile loading were examined. The results show that FRC with spiral fibres outperforms that with hooked-end fibres, and is a promising construction material in resisting dynamic loadings.

► Dynamic split tensile tests are conducted to study the dynamic tensile properties of FRC.
► The spiral FRC shows higher strain capacity, toughness, crack controllability and ductility.
► The spiral FRC also shows higher rate sensitivity to both strength and energy absorption.
► The test results demonstrate the effectiveness of the impact resistance capacity of the spiral FRC.