Transient dynamic behavior of polypropylene fiber reinforced mortar under compressive impact loading

The dynamic characteristics and the constitutive relationship, of polypropylene fiber reinforced mortar (PFRM) materials, were investigated under compressive impact loading. The impact tests were carried out using an improved Split Hopkinson Pressure Bar (SHPB) equipment installed with confining pressure device. Both the static tests and SHPB impact experiments of PFRM were conducted to study the effect of water-cement ratios, fiber volume fractions, and strain rates, on the blast resistance performance of PFRM. The compressive strength, the dynamic elastic modulus, the toughness as well as the ductility of PFRM were analyzed. Experimental results show that the dynamic performance of PFRM materials is significantly affected by strain rates. Nevertheless, the strain rate effect decreases as the strength of mortar increases. Polypropylene fibers are able to improve the impact toughness. The dynamic constitutive law of PFRM was finally derived based on an improved Zhu-Wang-Tang (ZWT) dynamic constitutive model taking into account the material damage. The dynamic stress-strain curves from experiments can be well predicted by the proposed constitutive law which, consequently, can be used to describe the dynamic properties of PFRM materials.