3D printing concrete technology from a rheology perspective: a review

The flow and deformation of cement-based materials accompanies the full cycle of 3DPC technology and profoundly affects the quality of printed structures. Therefore, rheology is closely related to this technology. However, since printing materials undergo complex changes (from fluid to solid) during the entire technical process, it is extremely difficult to accurately obtain the rheological parameters of the material, which makes it difficult to characterize the material properties and explore the rheological laws within the technical cycle. In this regard, this article starts from the perspective of rheology, systematically reviews the performance requirements of 3DPC technology for printing materials, critically discusses the existing methods for characterization of material printability, including various conventional and unconventional methods, and clarifies the scope of application of each method. In addition, this article introduces several buildability models based on considering material time dependence, pointing out the direction for the performance optimization of printing materials.