Study on compressive properties and chloride permeability of ultra-high-performance concrete

In this work, two UHPC premixes were applied in investigating compressive strength and chloride permeability. Results indicated that the compressive strength of UHPC increased with content of steel fiber in standard curing. Compressive strength of type-A premix specimen with 2.0 vol% steel fiber was more than 150 MPa after heat curing. All UHPC in the experiment showed low chloride permeability under heat curing. Compared with type-B premix, the type-A premix had greater advantages in mechanical property and chloride permeability. In addition, the low porosity and dense microstructure of UHPC specimen were detected by mercury intrusion porosimetry (MIP) and scanning electron microscope (SEM), respectively. Furthermore, it was found that the introduction of fiber could refine the pore size distribution of specimen.