Effects of ambient temperature and relative humidity on early-age shrinkage of UHPC with high-volume mineral admixtures

•Early-age shrinkage of eco-friendly UHPC was investigated under different conditions.•GGBFS replacement can increase both autogenous and drying shrinkage markedly.•Mineral admixtures may increase the sensitivity of UHPC to the external RH.•FA replacement may trigger the formation of elephant skin under drying conditions.•Elephant skin can reduce water escapes from the young UHPC under arid conditions. This study focuses on the early-age shrinkage of ultra-high performance concrete (UHPC) with high-volume mineral admixtures. Two low cement UHPC mixtures, which have similar compressive strength with control mixture, were obtained with high-volume ground granulated blast furnace slag (GGBFS) or fly ash (FA) replacements. The effects of exposure temperature on autogenous shrinkage of sealed specimens and drying shrinkage were studied at early-age (