3D-printing of architected calcium silicate binders with enhanced and in-situ carbonation

This paper investigates the use of architected cellular and solid designs of materials via additive manufacturing and in-situ CO₂ circulation to augment the carbonation and mechanical properties of a calcium silicate-based cement (CSC) binder. A wollastonite-based binder was formulated for extrusion-based 3D-printing. Solid and cellular lamellar architectures were designed to probe the role of layered interfaces and higher surface area on the degree of carbonation (DOC), respectively. Two carbonation exposure scenarios, with and without in-situ carbonation were employed. The DOC, microstructural phases, and flexural strength were characterised using TGA, modified over-flow image analysis technique, and three-point-bending, respectively. By exploiting 3D-printing and harnessing the higher surface area of cellular architecture, the material obtained a significantly higher DOC (by 8.9-folds) and flexural strength (by 5.7-folds) compared to reference cast. In-situ carbonation of cellular architected materials can additionally improve early-stage deformation, DOC (by 12.9-folds) and flexural strength (by 16.5-folds), compared to cast.