Effect of water-powder ratio on shear thickening response of SCC

The effect of the water-powder ratio on rheological properties of three types of self-compacting concretes (SCCs)-powder type SCC, viscosity modifying admixture (VMA) type SCC and powder-VMA combination type SCC were tested by RHM-3000 ICAR rheometer. The application of the Herschel-Bulkley (H-B) model and the modified Bingham model was discussed, and the effect of the water-powder ratio on shear thickening response of three types of SCCs were compared. The results showed that yield stresses of the three types of SCCs increased with the increase of water-powder ratio for the concrete with the similar slump flow and air content. However, the plastic viscosities differed in the opposite sense. The shear thickening response of SCC was found decreased with the increase of water-powder ratio, and there was a critical water-powder ratio from shear thickening to shear thinning. The shear thickening response could be well described by both H-B model and the modified Bingham model with good correlations, but the parameter of c/μ in the modified Bingham model was found to be more sensitive to the change of shear thickening. The shear thickening response of VMA type SCC was found to be the most sensitive to the change of water-powder ratio, and the least was combination type SCC.