Evaluation of SCC yield stress from L-box test using the dam break model

Abstract

In this study, an analytical method for the dam break flow of non-Newtonian fluids is extended to model self-compacting concrete flow in the L-box test. The rheology of fresh self-compacting concrete is expressed by a Bingham model. To simplify the mathematical formulation, inertia forces and the effect of rebar are neglected and the fluid is assumed to be homogeneous. Several self-compacting concrete mixtures with different yield stresses are also tested to measure the L-box blocking ratio. The proposed model arrested profiles satisfactorily coincide with the experimental results. A relation between yield stress and the L-box blocking ratio is also derived. A comparison between the predicted values of yield stress and the experimental results shows that the proposed model successfully evaluates the yield stress of the tested samples. Moreover, it is observed that the proposed model is valid in the case of an L-box with rebar. Finally, a plot of the relative yield stress against L-box blocking ratio is presented that can be practically used for workability design of self-compacting concrete.