Creep behavior of steel fiber reinforced reactive powder concrete at high temperature

Reactive powder concrete (RPC) shows a great application potential owing to its superior strength and excellent durability. However, creep behavior at high temperature is a major concern, as scanty information is available in the past literature. Therefore, the aim of this paper is to investigate the creep behavior of RPC at high temperature. Creep behavior is further segregated into free thermal strain, short-term creep and transient strain based on different thermo-mechanical regimes. Steady-state thermal and loading conditions and transient thermal and loading conditions were considered. Tests were carried out from 10 to 60% stress level of ambient and high-temperature compressive strength ratios and up to target temperature of 900 °C. The result shows that short-term creep of RPC increases considerably above 500 °C and the increase under the same loading ratios at 700 and 900 °C is approximately 13 and 23 times as that of short-term creep at 120 °C, respectively. Furthermore, increased stress level also triggered the short-term creep within the same target temperature. The evolution of free thermal strain and transient strain were slow below 250 °C. However, at higher temperature, the increase in strain rate becomes noticeable. It was found that heating rate has a direct influence on the expansion of RPC. On the other hand, transient strain was not affected by increasing heating rate from 3 to 5 °C/min. Finally, fitting equations were proposed which will be useful in fire safety design of RPC structures in computer programmes.