Drying of 3D Printed Mortar Filaments at Early Age Assessed by X-Ray Computed Tomography

Abstract

3D extrusion-based additive manufacturing is known as the most widely applied printing strategy for digital fabrication of civil engineering materials. This construction method does not only require specific rheological properties and structural build-ups rates, but also mechanical properties comparable to conventional materials. In the current work, manually cast mortar filaments consisting of cement paste and glass beads are used to mimic the 3D printed cement-based materials. We first compare the 3D tomography of mortar between sealed and dried conditions with or without mold constraint at early age. We then carry out the 3-point-bending tests for sealed and dried mortar. Our results suggest that at very early age before setting, drying phenomena induce irreversible microcracks which lead to a deterioration of mechanical strength of the filaments.