The relationship between dry rheology and particle shape of natural and manufactured sand

Understanding the effect of particle shape on dry rheology is considered to be an important aspect in order to replace natural sand used in concrete with man-made manufactured sand. There is a significant difference in particle shape and surface texture between crushed rock material (aggregates) and natural sand. The crushed aggregates are normally less rounded and have less equally shaped dimensions compared to natural sand. Thus, the flow ability of the concrete will be different. The main difference is explained by a difference in the wet rheology of the cement paste which in turn is affected by the smallest particles in the size range from microns to a few millimetres. In previous research, it has been demonstrated how different crushing techniques affects the shape of the produced particles. In many cases it is believed that Vertical Shaft Impact (VSI) -technology is the way forward to replace natural sand. The aim of this paper is to investigate the relationship between dry rheology measured with the so called flow cone and particle shape parameters measured with an optical image analyser technique