A comprehensive review on fresh and rheological properties of 3D printable cementitious composites

The undeniable potential of 3D printing technology to revolutionize global manufacturing processes has led to the emergence of advanced, digitalized, and fully automated construction techniques. Despite the growing interest in this technology, a significant challenge still exists in the development of cement-based printing material due to the complex interaction of various fresh and rheological property parameters. This review comprehensively explores fundamental fresh properties (flowability, buildability, extrudability, pumpability and open time) and rheological properties (static yield stress, dynamic yield stress, plastic viscosity) essential for the formulation of 3D printable cementitious composites, with and without fibres. The results obtained from different rheometers for successful 3D printed mixes are also summarised, highlighting variation in recorded values. Moreover, the review thoroughly investigates factors affecting both fresh and rheological properties, such as the type of supplementary cementitious materials, fibre type and dosage, superplasticizer, and viscosity-modifying admixture. It also identifies the clear impact of these parameters and further recommends the optimal range of some properties, such as a flowability value between 160-200 mm, to achieve desirable 3D printability of cementitious composites. Overall, this review offers valuable insights for developing new mix compositions suitable for 3D printing and serves as a useful tool in establishing guidelines for 3D printable cementitious composite materials, which are currently lacking but crucial for research, development, and application in this field.