Experimental study on the thermal properties of a novel ultra-high performance concrete reinforced with multi-scale fibers at elevated temperatures

•A novel multi-scale fiber reinforced ultra-high performance concrete (MSFUHPC) is developed.•The thermal conductivity, specific heat, and thermal expansion of MSFUHPC at high temperatures are studied.•The effects of multi-scale fibers on the thermal properties of MSFUHPC are discussed.•An empirical formulas for predicting thermal parameters of MSFUHPC are proposed.