Estimation of the yield stress and distribution of large aggregates from slump flow test of self-compacting concrete mixes using smooth particle hydrodynamics simulation

Abstract

A wide range of normal strength self-compacting concrete (SCC) mixes with a maximum aggregate size (g) of 20 mm ranging in compressive strength from 30 to 80 MPa were prepared in the laboratory, and the times t₅₀₀ and t_stop of each mix were recorded in the slump flow test. The entire cone flow test was then simulated from the moment the cone was lifted until the mix stopped to flow using the three-dimensional mesh-less smoothed particle hydrodynamics computational approach, treating the SCC mix as a non-Newtonian Bingham fluid. This numerical simulation had two aims. First, to investigate whether the yield stress τ_y of the mix could be accurately estimated from the measured t₅₀₀ and t_stop times knowing the plastic viscosity of the mix. The latter was estimated by a micromechanical procedure. Second, to compare the distribution of coarse aggregate particles larger than or equal to 8 mm in the cone spread after it stopped to flow as revealed by the numerical simulation with the distribution of the aggregate particles of the corresponding sizes in the cut sections of the cured test cone spread. The large coarse aggregate particles in the size ranges (8 ≤ g < 12, 12 ≤ g < 16, 16 ≤ g < 20 and g ≥ 20 mm) of the test SCC mixes were color coded with non-toxic non-water soluble paints so that the outlines of the aggregate particles could be clearly distinguished in the cut sections of the hardened cone spread and compared with the numerical simulations. It is shown that both aims of the investigations were successfully attained.

Keywords:

• 3D simulation
• self-compacting concrete (SCC)
• yield stress τ_y
• smoothed particle hydrodynamics (SPH)
• plastic viscosity
• coarse aggregate distribution