  A new thixotropic model is developed integrating the Papanastasiou-Bingham
model with thixotropy equations to simulate the flow behaviour of Tremie
Concrete in the Material Point Method framework. The effect of thixotropy on
the rheological behaviour of fresh concrete is investigated by comparing field
measurements with numerical simulations. The comparison yields new insights
into a critical and often overlooked behaviour of concrete. A parametric study
is performed to understand the effect of model parameters and rest-time on the
shear stress response of fresh concrete. The Material Point Method with the
Papanastasiou-Bingham model reproduces slump-flow measurements observed in the
field. The novel model revealed a decline in concrete workability during the
Slump-flow test after a period of rest due to thixotropy, which the physical
version of the test fails to capture. This reduction in workability
significantly affects the flow behaviour and the effective use of fresh
concrete in construction operation.
