Preparation and performance analysis of 3D printed lightweight EPS concrete: Insights from the excess paste theory

3D printed EPS concrete integrates the advantages of 3D printing technology and EPS lightweight concrete, offering the potential to reduce carbon emissions and enhance the environmental sustainability of construction. In this study, we successfully printed EPS concrete with densities ranging from 500 to 1900 kg/m3, using EPS particles to substitute for sand up to 100% volume ratio. The rheology of the mortars was elucidated through the excess paste theory. We introduced a composite aggregate model to calculate excess paste volume when composite aggregates were used. This study revealed that aggregates with distinct properties exhibited different excess paste layer thicknesses under similar rheological states. To address this, the excess paste thickness ratio of different aggregates was measured, enabling precise calculation of excess paste thickness, which aligns with mortar rheological properties. The study further indicates that the relatively high static yield stress of 3D printed concrete mitigates the floating of EPS particles, thereby promoting the uniformity of EPS concrete.