Modelling the flow of fresh concrete: The slump test

In this thesis, the slump of concrete has been studied using both a simple analytic expression and transient finite element computations. These techniques are valid for modelling the slump of any material possessing a yield value and a plastic viscosity.; A simple two parameter analytic expression was derived relating the slump to the material yield value. The expression was written in a dimensionless form and the results compared with slumps of concrete reported in the literature, and with mini-slumps which were performed on mayonnaise and toothpaste. The slump value predicted by the model, for a given yield value, was in good agreement with both the concrete slump data, and the mini-slump data. This agreement confirmed that the scaling used in the analysis was correct. The major shortcoming of the model was its poor prediction of the slump shape.; Finite element simulations using the programs DYNAFLOW and FEAP were performed to simulate the slumping process. For using these programs, a viscoplastic algorithm was developed using a solid mechanics approach. This model included the yield and viscous properties associated with a Bingham material, but also included the elastic properties associated with the solid before yielding. The expressions derived from this model resulted in an algebraic combination of the purely elastic and purely plastic algorithms. Thus the conversion of a purely plastic code, in which the elastic response is already calculated, to a viscous code was relatively straightforward.; Simulations of a purely plastic material using an infinitesimal deformation analysis did not agree with the analytic, or experimental results. Inclusion of viscosity did not result in any improvement in the simulations. Because of the large local deformations located within the slumping material, a finite deformation analysis was used. These simulations resulted in the prediction of realistic slump shapes and acceptable agreement with the experimental data. It was found that addition of viscosity did not alter the final slump. The only effect which the viscosity had on the slump was through scaling of the time taken to reach the final slump value. (Abstract shortened with permission of author.)...