Design of Eco-Efficient Concrete for Digital Fabrication

Abstract

The development of cementitious materials for 3D printing (3DPC) still presents many material and structural challenges, as well as ecological fragilities. 3DPC formulations require a high amount of cement and SCM to achieve rheological properties that meet printing requirements. Therefore, it is imperative to study alternative materials and (partial) substitutes for Portland cement to reduce the carbon footprint of 3DPC, particularly in the long-term vision. The use of locally available SCM reduces the costs and carbon dioxide (CO2) emissions associated with the production of 3DPC, while at the same time adding value to local and abundant industrial waste or by-products. As part of the DigiCrete Project, this study aimed to study potential ternary mixtures for 3D printing using national materials, including waste glass powder. At the first stage, paste, fresh state, hardening, mechanical properties, and carbon efficiency were studied. Using a centered factorial plan, the influence of the main variables of the mixture on the properties of 3DPC was evaluated, and the main effects of the mixture factors on the responses and possible interactions were identified. This knowledge can facilitate protocols for optimizing 3DPC compositions. The potential and optimized mixtures at the paste level went on to be studied at the mortar level. The results showed that it is possible to correlate results from traditional tests (spreading, slumping) in the study of mortars and parameters from the study of pastes and establish a printable mortar. Finally, it was possible to conclude that using local materials, including the industrial waste studied, is viable for the 3D printing of cementitious materials.