The effect of vibration on the rheological properties of fresh concrete

Synopsis Using a set-up in which the bowl of a two-point workability test apparatus was mounted on an electro-magnetic vibrating table, measurements were made on unvibrated fresh concrete and on the same samples under vibration. It was shown that when vibration is applied the flow properties of fresh concrete are no longer represented by the simple linear Bingham model but approximate to those of a power law pseudoplastic with zero yield value. At very low shear rates behaviour approximates to that of a Newtonian fluid and, subject to the exceeding of a small threshold condition, fluidity decreases as a simple exponential function of the maximum velocity of vibration.