ABSTRACT

A number of research scientists have tried to apply the same experimental process as that used with newtonian fluids to fresh concrete. Thus, as an example,

coaxial viscometers of extremely large dimensions, considering the sizes of the larger aggregates, have been built, and curves have been plotted giving torque as a function of angular velocity. Unfortunately, the results obtained prove to be disappointing when we try to translate them into rheological behaviour laws obeying Noll general principles. The main reason for this is simple: fresh concrete is a highly heterogeneous material, with extreme internal mechanical discontinuities, and assuming medium continuity is unacceptable. This leads to the very notions of stress and gradient, which are inseparable from the continyous medium concept, being inapplicable in these instances.