Computational fluid dynamics modelling of the concrete fresh state behaviour: from identification of rheological properties to casting flow simulation

Cementitious composites with adapted rheology are becoming increasingly used in a wide variety of civil engineering applications. Assessing the fundamental rheological properties of cement suspensions is a crucial task, instrumental not only to mix-design of SCCs and assessment of its fresh state performance, but also to the design of casting procedures, such as pumping, grouting, underground and underwater injections etc., where the rheology of the fluid may discriminate the successful accomplishment of the application. The measurement of the fundamental rheological properties of cement suspensions is a not simple task and requires dedicated and expensive equipments which are not compatible with field applications and may not even be available in every laboratory. Correlations between fundamental properties and field test measurements have hence been sought and, in some cases, quite well assessed, as, e.g., for the yield stress vs. the spread diameter in slump/minislump flow test. As for the viscosity, different attempts have been made, e.g. with the Marsh cone flow time or with the time to reach a prescribed diameter in the slump flow tests. This works aims at providing further evidence to the aforementioned correlations, with reference to a broad range of cement pastes and mortars formulated from High Performance Fiber Reinforced Cementitious Composites (HPFRCC). A robust assessment by means of Computational Fluid Dynamics (CFD) modelling will be performed, employing an approach developed by the second author. The “simulation” of the casting process of a structural element made with a highly flowable concrete will be finally performed as an auspice to address the use of CFD in civil engineering to “tailor” the material composition and the casting process to the intended application.