Abstract
The early-age shrinkage of ultra-high performance fiber reinforced concrete (UHPFRC) in dry, sealed, and soaked curing was systematically measured. The calculation model of early-age shrinkage was established based on the theory of shrinkage of cementitious materials. According to the results of the relative humidity, hydration degree, pore structure, and elastic modulus of hardened slurry, the shrinkage calculation model in different curing conditions was calibrated. The results show that the early-age shrinkage of UHPFRC can be divided into three parts: chemical shrinkage, autogenous shrinkage caused by self-drying, and drying shrinkage caused by external drying. Based on the degree of hydration, the chemical shrinkage model was established. Based on the pore structure, the hydration degree, and the relative humidity of hardened slurry, the autogenous shrinkage model was established by introducing the effective pore coefficient. The drying shrinkage model was established based on the internal humidity. According to the shrinkage of soaked samples, the calculated value of chemical shrinkage in sealed and drying conditions was calibrated. This research provides theoretical support for the structural design and engineering application of UHPFRC.
Highlights
Ultra-high performance fiber reinforced concrete (UHPFRC), a special cement-based composite material, can be used as structural or protective material used in harsh environments in long-term service of important projects, due to its excellent mechanical properties and durability
It was worth noting that the shrinkage of UHPFRC in sealing condition was even higher than that in drying condition after 11 days. is rule is contrary to the shrinkage development of ordinary concrete (OC), which has been discussed by this research group in the preliminary work [13]. e shrinkage
In the sealing, soaking, and drying conditions, the shrinkage of UHPFRC shows a rapid growth in the early stage and a gradual slowdown in the later stage
Summary
Ultra-high performance fiber reinforced concrete (UHPFRC), a special cement-based composite material, can be used as structural or protective material used in harsh environments in long-term service of important projects, due to its excellent mechanical properties and durability. In recent years, it has become a hot spot for researchers [1, 2], and there have been a lot of engineering applications. UHPFRC is designed with the compact packing model, removing the coarse aggregate and adopting the ultra-low water-cement ratio, increasing the amount of the binder material and incorporating the active admixture
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