Influences of packing properties on the workability of cementitious materials using mixed recycled fine aggregate derived from decoration waste

Recycled aggregate derived from decoration waste, typically consisting of various compositions, makes the workability of mixtures difficult to predict. This study investigated a widely applicable indicator, the void ratio of saturated surface dry state, to establish an association between the properties of mixed recycled aggregate and workability. The packing properties and morphological parameters (including angularity, aspect ratio, circularity and roundness) of the aggregate were measured. The workability of mixture was evaluated through tests of flowability, yield stress and plastic viscosity. Results showed that the void ratio of saturated surface dry state had a strong correlation with the workability of fresh mixtures. This indicator reflected the impact of morphology, gradation and water absorption of the mixed recycled aggregate on packing properties. Based on the indicator, mixture with an excess paste thickness of 10-27 mu m exhibited an optimal workability for the application in cementitious backfill materials. The findings of this research can provide a practical indicator to predict the workability of cement-based material incorporated mixed recycled aggregate.