Application of Copper Slag in Ultra-high Performance Concrete

Ultra-High Performance Concrete (UHPC) was hindered by the use of non-renewable quartz sand, so there was a need to find a new sustainable material to replace quartz sand. This study investigates the possibility of using copper slag as an aggregate instead of quartz sand to make sustainable UHPC. To ensure the workability and good particle build-up of UHPC, the copper slag particle size was differentiated into three classes to replace quartz sand of the same particle size. UHPC mortars were prepared at 0, 25%, 50%, 75%, and 100% substitution rates and tested for flow, compressive, flexural, and pore structure. The test results showed that copper slag has a dense structure and good compression properties. The smooth surface and poor water absorption of copper slag can significantly improve the flowability of UHPC mortar. The inherent high density, high abrasiveness, high compressibility, and sharp edges of copper slag material can improve the strength of UHPC mortar. A good particle gradation allows the material to build up more compactly and reduces porosity. The results of the study show that it is feasible to use copper slag as a fine aggregate to replace quartz sand at a substitution level of 50%.