Influence of Calcined Clay Type on the Rheology of LC ³ ‐Based 3D‐Printable Concrete with CO ₂ ‐Enriched Mixing Water

Abstract

The construction industry contributes significantly to global CO ₂ emissions while consuming vast amounts of natural resources. Addressing resource scarcity and reducing environmental impact therefore require both more sustainable binders and innovative construction technologies. Digital fabrication methods such as 3D concrete printing offer opportunities for resource‐efficient construction by eliminating formwork and reducing material consumption. In parallel, alternative binders such as limestone calcined clay cement (LC ³ ) have emerged as promising low‐carbon options. Recently, the direct introduction of CO ₂ into fresh concrete has attracted increasing attention. In addition to enabling partial CO ₂ fixation, dissolved CO ₂ may influence rheological properties of fresh mixtures, which are crucial for buildability and shape stability in 3D concrete printing. While these effects have been studied for ordinary Portland cement (OPC) systems, limited knowledge exists for LC ³ binders, particularly regarding the role of calcined clay mineralogy. This study investigates the interaction between CO ₂ ‐enriched mixing water and LC ³ binder systems containing three different calcined clays. The focus lies on static rheological parameters relevant for additive manufacturing, including spread flow diameter over time and static yield stress, determined using Hägermann flow table test and fast penetration tests. The results aim to provide a basis for integrating CO ₂ directly into the printing process as a potential rheology modifier.