Improving environmental efficiency of ultra-high-performance concrete (UHPC) through appropriate application of ultrafine quartz powder

Ultrafine quartz powder (UQP) can be considered as a kind of physical fillers in concrete production. To improve the environmental efficiency of optimized ultra-high-performance concrete (UHPC), based on Modified Andreason and Andersen packing model (MAA), the UQP was utilized to replace ordinary Portland cement and optimize packing system of UHPC. Subsequently, the physical and hydrated characteristics of UHPC were studied. The results indicate that when UQP is a substitute for Portland cement in the production of UHPC, the influence of its variation content on later age compressive strength of UHPC is difficult to be distinguished. Corresponding to that, the prominent microstructure of the optimized UHPC is developed with high packing density when an optimum addition content of UQP is about 30%. Furthermore, the comprehensive evaluation which is quantified into five indexes (carbon footprint, energy emission, unhydrated clinker, binder and clinker index) demonstrates that the optimized UHPC has a much lower ecological effect in comparison with the majority of UHPC reported in published references, which provides a broad prospect for engineering application of the sustainable UHPC.