Response of fine-grained fiber-reinforced concrete under different mechanical loading conditions

This paper presents an experimental study of the deformation and energy absorption of fiber-reinforced concretes under compression at different strain rates. Static load tests are carried out using the Zwick-Roell Z100 universal testing machine at a strain rate of $30\times10^{-6}$ s$^{-1}$. Dynamic load tests are carried out in the range of strain rates $200$–$800$ s${^-1}$ using the Kolsky method, which implies loading of the studied sample in a split Hopkinson pressure bar system. Specimens are made from a concrete mixture with the addition of wavy steel or polypropylene fibers with a volume fraction of $1.5 \%$. As a result of experiments and processing of the recorded strain pulses of measuring bars, the deformation diagrams and the corresponding diagrams of the specific energy absorption for the fiber-reinforced concretes under study are constructed. For all concretes being studied, the diagrams of deformation and energy absorption have similar trends and show an increase in the strength and energy before fracture initiation with an increase in the strain rate.