(202e) Rheology of Cement-Based Pastes for 3-D Printing Applications

Many industrial production processes are turning to additive manufacturing technologies as a promising alternative to reduce production costs and time, to add design flexibility and move towards more sustainable processing and improve manufacturing safety. The construction industry is a more recent sector to join the additive manufacturing revolution and researchers around the world are pushing the limit to demonstrate the printability of large-scale structural components. However, research on the fundamental materials science of printed cementitious bodies already lags far behind. To ensure sustained gains from additive manufacturing in construction, researchers must address issues regarding printability and microstructural continuity of printed infrastructure materials.

This work seeks to develop well-formulated additive systems aimed at enhancing cement-based pastes for effective printing. Various combinations of polymers including superabsorbent polymer, specialty polymers, viscosity modifying admixtures, superplasticizers and mineral-based additives, with desirable properties, and cement were explored. Various time-domain rheology experiments were performed to explore the flow properties, i.e. the yield stress and plastic viscosity, of select pastes were measured using oscillatory and flow rheometry. Pastes were also printed in different geometries to explore the process operating variables including extrusion speed, layer thickness and print rate. The research goal of this work is the identification of suitable mix formulations and printing conditions for effective deposition.