Heat treatment is often required for ultra-high-performance concrete (UHPC) to achieve high strength. To broad its use in construction, the effect of different curing conditions on the properties of UHPC has been developed for many years. The experimental investigation of large scale ultra-high-performance fibre reinforced concrete (UHPFRC) beams is limited. In the present study, UHPFRC specimens and concrete cured at 20 °C were prepared to investigate the properties and flexural behaviour. The standard cubic compressive strength of UHPFRC specimens cannot be achieved at curing temperature of 20 °C. The bearing capacity under flexure was enhanced with the increase of reinforcement ratio. The failure modes of beams changed from ductile to brittle as the reinforcement ratio increased from 1.26 to 9.50%. The flexural behaviour of UHPFRC beams cured at room temperature was in accordance with the UHPFRC beams cured at high temperature in previous studies. In addition, the calculation model of CECS38-2004 underestimated the bending moment capacity of the under-reinforced UHPFRC beams (with reinforcement ratio from 0 to 7.85%) and overestimated the bending moment capacity of the UHPFRC beams with high reinforcement ration of 9.50%.

In the present study, specimens with four different dimensions and concrete beams with six different reinforcement ratios were prepared to investigate the properties and flexural behaviour of ultra-high-performance fibre reinforced concrete (UHPFRC) cured at 20 ºC. The standard cubic compressive strength of UHPFRC specimens cannot be achieved at curing temperature of 20 ºC. For UHPFRC beams, the bearing capacity under flexure was enhanced with the increase of reinforcement ratio. The failure modes of UHPFRC beams changed from ductile to brittle as the reinforcement ratio increased from 1.26–9.50%. Moreover, the ductility of UHPFRC beams decreased with the increase of reinforcement ratio from 1.26–9.50%. The flexural behaviour of UHPFRC beams cured at room temperature was in accordance with the UHPFRC beams cured at high temperature in previous studies. In addition, the calculation model of CECS38-2004 underestimated the bending moment capacity of the under-reinforced UHPFRC beams (with reinforcement ratio from 0–7.85%) and overestimated the bending moment capacity of the UHPFRC beams with high reinforcement ration of 9.50%.