Low carbon design of an Ultra-High Performance Concrete (UHPC) incorporating phosphorous slag

In this study, a low carbon design of an Ultra-High Performance Concrete (UHPC) is performed by incorporating high-volume phosphorous slag (PS). The modified Andreasen and Andersen (MAA) particle packing model is employed to obtain a densely compacted particle skeleton, while the PS is employed to replace cement by 10–50% (weight). Then, the effect of the added PS on fresh and hardened properties of the designed UHPC are investigated. The results indicate that the addition of PS significantly improves the flowability and reduce its autogenous shrinkage during the early stage. Compared to the reference sample, the UHPC with PS has lower compressive strength at 3 days, while presents comparable strength at 28 days. Microstructure analyses verify that the added PS obviously prolong the dormant period of cement hydration in UHPC, which actually is beneficial for obtaining a stable and microstructure optimized UHPC. Additionally, the carbon foot print calculation demonstrates that appropriate application of PS in the production of UHPC is a promising approach to develop a cleaner building material.