Multiscale model links water content to cement paste flow for 3D printing
Researchers connected atomic-scale interactions with particle-based simulations to explain viscosity and shear thinning in fresh cement
Researchers used multiscale modeling to examine how water content affects the flow of freshly mixed cement paste, according to a study in the Journal of Applied Physics. The work identified a reduced viscosity as the water-to-cement ratio increased, and in comparing the simulations with experiments on wet cement, the team observed the same key qualitative trends.
The American Institute of Physics (AIP), which summarized the study, stated that construction in disaster-struck areas, military applications, and other extreme environments was often difficult or unsafe for workers. It described printing cement offsite and transporting finished pieces to the location as an alternative, but noted a gap in understanding of what controls the flow of wet cement, which limited the ability to improve building performance.
The team first modeled the atomic-scale interaction between cement surfaces in the presence of water, then carried that result into a larger model.
“We first calculated how water affected the interaction between cement surfaces at the atomic scale and then used that information to construct an effective interaction for a much larger particle-based model,” said study author Subhadeep Pal.
Pal compared the multiscale approach to using a microscope to look at cement at different levels. By examining what cement particles did during flow, rather than relying on the viscosity curve alone, the authors proposed a microscopic mechanism for the observed shear thinning.
“I hope this work provides a useful framework for connecting molecular-scale cement science with the particle-scale behavior that ultimately controls processing,” Pal said.
Cement is a complex material with irregular particles, and the team’s model was a simplified starting point. It was used to isolate relationships between water content, particle interactions, shear, and viscosity, and future work will add more elements to the models to better understand cement flow and its use in 3D printing.
