Rheology and Setting Control of Concrete for Digital Construction

To ensure a successful outcome when using cementitious materials during three-dimensional (3D) printing operations, the effects of chemical admixtures on rheological and setting behavior must be carefully adjusted to accommodate the needs for pumping, extrusion, deposition, and self-sustainability without the support of formwork. This paper highlights potential solutions offered by chemical admixtures, while discussing various testing methods and important influencing parameters. The impact of commercial polymers on viscosity, initial yield stress, thixotropy, and their variations over time are reported. Influencing factors, such as mixing energy and material interactions, are discussed. Accelerating and strength-enhancing admixtures are used to illustrate the adjustment of setting and early strength development of concrete. Understanding the possibilities of modifying fresh concrete properties will help to improve the robotic construction process as well as the design or adaptation of the printing equipment. Keywords: accelerator; admixtures; dispersants; mortar; rheology; thixotropy; three-dimensional (3D) printing; viscosity.