Behavior of Hybrid-Fiber Engineered Cementitious Composites Subjected to Dynamic Tensile Loading and Projectile Impact

Abstract

The characteristics of engineered cementitious composites (ECCs) subjected to dynamic tensile loading and high-velocity projectile impact have been investigated and are reported in this paper. Hybrid-fiber ECC containing a combination of high-modulus steel fibers and relatively low modulus polyethylene fibers was adopted to achieve a desired balance between the ultimate strength and the strain capacity of the material required for impact- and blast-resistant structures. Dynamic uniaxial tensile tests at varying strain rates of $2\times {10}^{-6}\text{to}0.2{\mathrm{s}}^{-1}$ were carried out, and ECC was found to be able to provide much higher enhancement in tensile strength than plain concrete and still be able to maintain pronounced tensile strain-hardening behavior. At higher rates of strain, ECC showed multiple-cracking behavior, similar to that observed from quasi-static tests, with tight crack width of about $0.1\mathrm{mm}$ . The results from high-velocity $(300–750\mathrm{m}∕\mathrm{s})$ impact tests demonstrated the potential of ECC in providing improved functionality (compared with concrete) as a protective material in aspects such as increased shatter resistance with reduction in damage arising from scabbing, spalling, and energy absorption associated with distributed microcracking.