Effect of compound mineral powders on workability and rheological property of HPC

The compounding effect of silica fume (SF) with phosphorus slag (PS) or limestone (LS) powder is investigated in this paper. It is found that such a compounding can achieve various rheological behavior of HPC. The compound powders of PS with SF lower plastic viscosity and yield stress of fresh concrete, but increase the slump and promote continuous flowability of concrete greatly. However, the compounding of LS with SF increases the yield stress, but decreases both slump and slump flow of concrete, although the viscosity remains broadly unchanged compared with the concrete containing LS only. It is demonstrated that rheological property can be highly correlated with the surface characteristic of each component of the compound powders. Based on the experimental work, the appropriate fractions of the components in these compounds, especially the optimum content of SF, have been suggested for improving rheological property of HPC.