2D stationary computational printing of cement-based pastes with time-dependent rheology

Abstract

Additive manufacturing is rapidly emerging as a potentially transformative technology for the construction industry. Many technical hurdles, however, are yet unresolved including the formulation of robust, standardized cement-based printing pastes. To hasten the development of rheologically sound materials for printing, a combined experimental and computational approach has been taken. A new, efficient strategy for computational printing was recently introduced. The new method, 2-D Stationary Computational Printing (2D-SCP), has been shown to map well to experimental print outcomes. Here, the 2D-SCP strategy was extended to include time-dependent rheological effects due to hydration-related structuration. The time-domain rheological properties of cement-based printing pastes were determined from experimentally measured static yield stress values. As a benchmark, a tubular form was used for printed objects. The numerical models were then validated by comparing the polished sections of the printed objects with that produced using the 2D-SCP model. The importance of structural build-up and related rheological changes i.e. static yield stress, on 3D printing of the experimental cement pastes was quantified. The obtained results show high fidelity between 2D-SCP prints and experimental objects. This newly developed computational printing strategy can assist in targeting optimal paste design for 3D printing applications.