This study investigates the influence of different curing regimes on the microstructure and macro properties of ultra-high performance fiber reinforced cementitious composite （UHPFRCC）, and aims to discover whether it is possible to produce qualified UHPFRCC using different curing regimes. A control mix of UHPFRCC is prepared. The mechanical performance and the short-term durability of the UHPFRCC matrix under three curing regimes are studied. In addition, the microstructures of the UHPFRCC matrix with different curing conditions are analyzed by combining scanning electron microscopy （SEM） and mercury intrusion porosimetry （MIP）. The results explore how different UHPFRCC curing regimes affect its microstructure and how the microstructure affects its macro behavior. Heat and steam curing for 3 d is succeeded to produce the UHPFRCC with nearly the same mechanical properties and durability as those of the 90 d standard curing. However, the heat cured UHPFRCC does not show great resistance to chloride-ion penetration.
This study aims to reveal the mechanism that how the content of steel fibers and strength grades affect the macro performance of the ultra-high performance fiber reinforced cementitious composite （UHPFRCC） and to study the UHPFRCC durability under the combined effect of loads and environments. Three types of high and ultra-high performance fiber reinforced cement composites with different strength grades （100, 150, 200 MPa） and different steel fiber volume fractions （0%, 1%, 2%, 3%） are prepared. The main properties of mechanical performance and short-term durability are studied. A preloading frame is designed to apply a four- point load external flexural stress with a stress selection ratio of 0.5 for UHPFRCC150 specimens. The results show that the growth in strength grade with a proper content of steel fiber greatly increases the strength and toughness of the HPFRCC and the UHPFRCC while decreasing the dry-shrinkage ratio. For the loaded specimens, the existence of steel fiber can reduce the negative influence of tensile stress on the Cl- penetration resistance of the UHPFRCC in addition to improving its ability to resist the freeze-thaw damage.
