To obtain reliable measures of cement paste rheology several precautions need to be taken to insure reproducibility. Also, for possible prediction of concrete rheology from cement paste, the measurements should be made in a variable geometry rheometer, i.e., parallel plate. The gap should be carefully selected to reflect the true value of the distance between the aggregates. The method developed by Garboczi and Bentz is deemed adequate to predict the gap in concrete from the granulometry and the amount of cement paste selected. The limited results show that the gap greatly influences the yield stress while having practically no influence on the viscosity. Further measurements and studies need to be performed to confirm these results.
The author would like to thank John Winpigler for taking all the measurements reported in this paper, and James Clifton, Vince Hackley, Kenneth Snyder and Edward Garboczi for useful conversations and suggestions for the manuscript.