Evaluating the Influence of Aggregate Content on Pumpability of 3D Printable Concrete

Abstract

3D concrete printing technology has gained huge momentum in the past two decades. The enhanced geometric freedom associated with 3D concrete printing could be beneficial for a variety of applications. However, the relatively high binder content in 3D printable concrete makes them less sustainable compared to mould-cast concrete. Therefore, developing printable mixtures with the required rheological behaviour combined with enhanced sustainability is very important. In this study, different concrete mixtures were prepared by replacing ordinary portland cement with ground granulated blast furnace slag. A polycarboxylate-ether-based superplasticizer and a cellulose-based viscosity modifying agent were used as chemical admixtures. A maximum aggregate size of 2 mm was used, and the aggregate-to-binder ratio (a/b) was varied from 1.0 to 1.8 to reduce the binder amount. The designed mixtures were tested for their pumpability with a screw-based pump system allowing to measure the discharge rate and pumping pressure. The pumping pressure increases as the aggregate content increases. Rheological properties of these mixtures were determined by fitting to the Bingham model. The yield stress and viscosity were found to increase with an increase in the aggregate content of the mixtures.