Effects of steel fiber content and type on dynamic tensile mechanical properties of UHPCC

Abstract

Ultra-high performance cementitious composites (UHPCC) has become the most prospective construction materials for both civil and military protective structures. In order to facilitate the structural design and calibration/validation of the constitutive model, the dynamic tensile (spalling) behavior of UHPCC is experimentally studied. By using a 50 mm-diameter conic variable cross-sectional Split Hopkinson Pressure Bar (SHPB), the dynamic spalling test on Φ48mm × 400 mm cylindrical UHPCC specimen is conducted. The tensile strain rate ranges from 14.3 s−1 to 214.8 s−1, and two typical steel fibers (micro-straight and hooked) with three volume fractions of 0%, 1.0% and 2.0% are investigated. The effects of steel fiber content and type as well as the strain rate on the dynamic spalling strength of UHPCC are experimentally assessed. It indicates that the dynamic spalling strength of UHPCC increases obviously with the strain rate rising up to ∼110 s−1, and also improves with increasing the content of both two typical steel fibers. When the strain rate increases higher than 60 s−1, the micro-straight steel fiber has relatively better effect on improving the dynamic spalling strength than the hooked one with the volume fraction of 1.0%. Furthermore, corresponding to each steel fiber content and type, the empirical dynamic increase factors (DIFs) for the dynamic tensile strength of UHPCC are formulated.