Ultra-High performance concrete (UHPC) with polypropylene (Pp) and steel Fibres: Investigation on the high temperature behaviour

Ultra-high performance concretes (UHPC) are advanced cement-based materials characterised by superior mechanical properties with respect to normal and high-strength concretes; however, their dense compact matrix can facilitate the onset of spalling at high temperatures. This problem is often coped up adding polypropylene (PP) fibres mix design, alone or other types fibres; steel enhance material’s tensile capacity. The paper presents a series tests on two UHPC (150 180 N/mm2) PP (0.27% volume) variable content (0% 1.92%), aimed investigating residual material after temperature exposure. experimental results compared available research small specimens exposed temperatures, dosages in from 0.03% 2%, 0 3%. this demonstrate that UHPCs need hybrid fibre reinforcement (PP + steel) withstand strength increases 200 °C exposure, all dosages; line literature. Available also shows loss possible hot conditions, as found present research, while do not always prevent occurrence samples.