Fresh self compacting concrete, a shear thickening material

In literature, the rheological properties of concrete have been investigated thoroughly, resulting in a simple description, in steady state, by means of the Bingham model. Self compacting concrete shows a lower yield stress, which in some cases is very close to zero, or can even appear to be negative when extrapolating the Bingham model. In the latter case, the Bingham model is not valid and other solutions must be found.In this paper, the non-linearity – or shear thickening – in the rheological behaviour of fresh SCC is described with the modified Bingham model, after the elimination of possible measurement artefacts. Analysis indicates that shear thickening is mainly correlated with the type of superplasticizer, the type of filler, the W/P-ratio and the slump flow of the concrete.