Performance of various strain-hardening cement-based composites (SHCC) subject to uniaxial impact tensile loading

Three different types of strain-hardening, cement-based composites (SHCC) as well as their constitutive cementitious matrices were investigated under uniaxial quasi-static and impact tensile loading. The normal strength matrix was combined with polyvinyl-alcohol (PVA) fiber in one composite and with high-density polyethylene (HDPE) fiber in another. The third composite material consisted of high-strength matrix and HDPE fiber. A modified Hopkinson bar was used to assess the impact resistance of SHCC in terms of stress-strain relationships at displacement rates of 6 m/s. The experiments were performed on specimens of two different lengths, for which, the strain rates were approximately 100 s(-1) and 200 s(-1), respectively. SHCC made of normal-strength matrix and PVA, the composite with considerable ductility under quasi-static loading, performed substantially worse at high strain rates than SHCC made with HDPE fiber. This could be traced back to the peculiar alteration of the fiber-matrix interaction depending on the type of fiber and corresponding bond properties (chemical bond in case of PVA fiber versus frictional bond in case of HDPE fiber). Furthermore, it was demonstrated that the effect of the increasing strain rates on the tensile performance of SHCC made with HDPE fibers can be controlled by adjusting the matrix composition, this being facilitated by the consistent and predictable strain rate sensitivity of the interfacial interaction between the HDPE fibers and the surrounding cement-based matrix.