High-fidelity SPH-DEM framework for mesoscopic rheological behavior of fresh fiber-reinforced concrete

Understanding mesoscopic component migration in fresh fiber-reinforced concrete (FRC) helps to control concrete construction quality. Studying of components’ movement in non-transparent flow requires a high-fidelity fluid-solid interaction method. This study employs a two-way coupled approach based on the SPH (Smoothed Particle Hydrodynamics) and DEM (Discrete Element Method) to simulate the rheological behavior of fresh FRC at mesoscale. The Herschel-Bulkley model is implemented to represent the shear thinning of mortar and aggregates settlement during vibrating compaction. With this high-fidelity framework, both the macroscale rheological behavior of fresh FRC as free surface flow and the mesoscale movements of coarse aggregate and fibers as suspended components can be well captured. After performing the high-fidelity preparations of fresh FRC, good agreements between experimental and numerical L-box tests and smart aggregate vibrating tests are reached. The proposed approach, in accordance with experimental evidence, shows that the fibers' orientation strongly depends on the flow speed. Moreover, the fibers’ orientation in high-speed flows tends to follow the same direction of flow, while fibers in low-speed flows tends to follow a random orientation pattern and block the flow.