Material-Design and Rheological Behavior of Sustainable Cement-Based Materials in the Context of 3D Printing (2022-06)¶

In recent years, the development of digital construction methods such as 3D concrete printing (3DCP) has attracted increasing interest by the construction industry. 3DCP has a potential to solving many problems currently encountered in this business sector. At the same time, the urgent need in introducing sustainable binders such as limestone calcined clay cement into the practice of construction has been increasingly understood. It seems logical and very promising to merge both concepts in order to achieve a considerable progress in the field. From a technical perspective, however, the implementation of such sustainable approaches can only succeed if fresh 3D printable materials yield rheological properties in accordance with the high requirements posed by the complex process chain of 3DCP. This article presents a methodological approach for the development of 3D printable concretes (3DPC). Rheometer tests and penetration tests were conducted to systematically investigate the time-dependent increase in the static yield stress. The extrudability and buildability of the mixtures were verified by printing wall elements. Due to the low cement content of the mixtures (<270 kg/m3), strength tests were performed as well. Despite the low clinker content, compressive strength values of approximately 30 MPa could be reached. The results attained in this work show that the use of supplementary cementitious materials enables establishing low-clinker concretes in the context of 3D concrete printing.