Controlling the rheological properties of cement for a submillimetre-thin shell structure

Thin shells are widely used in structural design and developing lightweight high-performance materials and composites. A fluid coating-assisted additive manufacturing method proposed in the literature shows great potential in fabricating lightweight composites using shell-like framework architectures. However, understanding the fabrication of thin shells by controlling the fluid rheology for a submillimeter-thin coating is still limited. As a demonstration, we investigated the effect of surface tension and yield stress of cement paste on the spreading and stabilisation on a curved honeycomb scaffold to form a thin-shell structure via a lattice-Boltzmann method simulation. We found the coating of cement paste is governed by the coupling effect of surface tension (gamma) and yield stress (sigma(y)), which not only controls the stability but also affects its geometry. The optimal ranges of gamma and sigma(y) were determined and their correlation was derived as a design guideline for future development of this cementitious thin-shell structure. As well, equivalent microscale rheological parameters (gamma = 0.015 N/m and sigma(y) = 3.42 Pa) were identified. This study improves our understanding of the fabrication of high-performance cementitious shells and sheds light on the fabrication of submillimetre-thin shells using a wide range of materials.

Automated summary

The study investigates the fabrication of thin shells by controlling fluid rheology, revealing the coupling effect of surface tension and yield stress on stability and geometry. The optimal ranges of parameters were determined as design guidelines for future development of cementitious thin-shell structures.