Relationship between water transport behaviour and interlayer voids of 3D printed concrete.

• In situ tracking water transport at the interlayer zone of 3D printed concrete using X-CT combined with CsCl enhancing. • The percentages of 0.1 mm-0.6 mm and 1 mm-4 mm voids size are observed to have an opposite effect on the water transport. • Connected or continuous voids induce a preferential water transport along the interlayer zone. • The spherical shape, independent and evenly distributed relatively voids were observed in cast concrete, while the irregular shape and interconnected or even continuous voids in 3DPC were detected. 3D printed concrete is a rising technology recently developed for construction industry. Unlike conventional concrete, since 3D printed elements are built by using a layer-deposition process, the distinct void generated between the printed concrete filaments considerably reduce mechanical strength and durability of 3D printed concrete. Using X-CT technology combined with CsCl enhancement, this study aims at investigating the water transport characteristics at different interlayer zones of 3D printed concrete, cast concrete as the reference. Meanwhile, the void characteristics of different interlayer zones are analyzed to establish quantitatively the relationship between the void distribution and the water transport process. It can be found that those voids at the interlayer zone led to a faster water transport along the printed concrete' interlayer zone than that of cast concrete. In addition, the percentages of 0.1 mm-0.6 mm and 1 mm-4 mm voids size are observed to have an opposite effect on the water. [ABSTRACT FROM AUTHOR]