Study of novel ultra-high performance concrete by replacing cement with different particle size of wollastonite

Ultra High Performance Concrete (UHPC) has been has been used far and wide in architectural field. Wollastonite microfiber (WF) has been shown to be effective in improving the brittle performance of UHPC. In this work, a series of Wollastonite Microfiber-Ultra High Performance Concrete (WF-UHPC) were synthesized by using WF as a low-activity fiber powder admixture to replace parts of cement in UHPC. Due to the smooth surface, the introduction of WF had improved the fluidity of UHPC slurry, which could make it fill all parts of the formwork more evenly. The maximum flexural strength and compressive strength of WF-UHPC could reach 19.5 MPa and 172.6 MPa in 28-day period, which were higher than that of UHPC. Furthermore, microfiber size of WF played a better bridging role, resulting in WF-UHPC possessed better shrinkage inhibition effect. The anti-freezing results indicated that the mass loss and strength loss of WF-UHPC after 300 freeze-thaw cycles were significantly reduced with the addition of wollastonite. This work provides consideration for the innovation of UHPC technology in the future and the research of replacement cement to mineral admixtures in UHPC.