Open-Span Printing Method for Assessment of Early-Age Deformations of Additively Manufactured Cement-Based Materials Using an Isosceles Triangle (2021-12)¶

Successful additive manufacturing of cement-based elements depends upon understanding the materials' fresh properties and their influence on early-age deformations. However, to be able to monitor early-age deformations of cement-based materials for 3D-printing applications, one must be able to assess these distortions “in situ,” that is, during the actual 3D-printing operation. This paper discusses the use of a new open-span printing method as a tool for evaluating the deformation of freshly printed plain cement paste filaments containing chemical admixtures. The method uses a rigid isosceles triangle as a support structure that allows for the deposition of filaments over varied span lengths. The vertical deformations of filaments printed with materials of variable composition (i.e., different solids content and types of chemical admixtures) were quantified. Elements printed using materials with increased solids content were observed to develop reduced mid-span deflection across span lengths larger than 12 mm. This test method can be used to inform the selection of materials in order to achieve suitable shape stability (e.g., to ensure minimal early-age deformations).