Experimental study on damage anisotropy of 3D-printed concrete exposed to sulfate attack.

• Fibre-reinforced sulfoaluminate cement-based composites were developed for 3D printing. • The mechanical and sulfate-attack resistance of 3DCP was experimentally assessed. • The damage anisotropy of 3DCP exposed to sulfate attacks was elucidated. • The influence of interfaces on the sulfate resistance was uncovered from meso-/microscales. 3D concrete printing (3DCP) technology has grown substantially in recent years and expanded from use in the development of architectural landscapes to the manufacture of load-bearing structures. The durability performance of 3D-printed concrete materials is crucial for the application of 3DCP in engineering structures. In this study, polypropylene (PP) fibre-reinforced sulfoaluminate cement-based composites were prepared for 3D printing, and their mechanical and durability performances after exposed to a sulfate-attack environment were experimentally assessed. The surface damage, mass loss, dynamic modulus, and residual strength of the prepared 3D-printed concrete were quantified during 150 cycles of sulfate attacks. The damage anisotropy of 3DCP exposed to sulfate attacks was introduced and elucidated from both the meso- and microscales. The pore characteristics of the matrix and interfaces were investigated through computerised tomography (CT) scanning and scanning electron microscopy (SEM) to uncover the influence of interfaces on the sulfate resistant performances. The results indicate that the damage anisotropy of 3DCP after exposed to sulfate attack was reduced due to the self-healing properties of sulfoaluminate cementitious composites. [ABSTRACT FROM AUTHOR]