The limit tension of the shift falls practically to zero, the plastic viscosity
Furthermore, the increase in the plastic viscosity of mortar was denoted by the flowing ability (flow time) results of the paste phase of mortar or concrete.
The higher sand content increases the yield stress and plastic viscosity of mortar due to confinement of some mixing water and enhanced interaction of sand particles, and thus destroys certain amount of the air-voids (Banfill 1994; Sa fiuddin 2008).
An attempt to modify the slump test to measure plastic viscosity showed the limits of such an approach .
The slope of this resulting curve according to the Bingham model will give the plastic viscosity and the intercept at zero shear rate will give the yield stress.
The intercept, Y(N * m), and the slope, V(N * m * s), of this line were considered to be related to yield stress and plastic viscosity, respectively.
The mean relative errors of yield value g and plastic viscosity h determination were respectively 4.
Relations of influence of viscosity enhancing agent (VEA) content on yield value g and plastic viscosity h of fresh mortars different in superplasticizer and cement type are presented in Figs 2, 3 and 4.
It can be seen that an addition of VEA significantly influences yield value g and plastic viscosity h of mortars and range of its changes with time.
In response to this fact, at least five concrete rheometers have been designed to measure both the yield stress and plastic viscosity of concrete.
The new approach presented here uses the relative plastic viscosity instead of the plastic viscosity.
By plotting all the data on a graph of the relative plastic viscosity versus the concentration of particles (i.