Rheological parameter ranges for 3D printing sustainable mortars using a new low-cost rotational rheometer

Abstract Concrete 3D printing in the field of construction is rapidly developing in recent years. Some key aspects of mortars used in 3D printing include good extrudability and sufficient load-bearing capacity to support their own weight during the printing process. Thus, the rheological properties of the fresh mortar should be determined since they have to be comprised between certain values to make mortars suitable for 3D printing. In this study, a low-cost rotational rheometer has been developed to obtain the rheological characteristics of different mortar mixtures apt for 3D printing. In order to validate it, numerical simulations have been undertaken, which have shown a good correlation between the experimental and analytical results. Furthermore, a comparison with another commercial rheometer has been conducted using a mortar without fibers and a common testing protocol, showing results with similar variability to other proficiency tests undertaken with cement pastes. In addition, the rheological behavior of various sustainable mixtures incorporating recycled materials and different types of fibers was studied. The article further examines how the types, lengths, and percentages of fibers influence rheological parameters, establishing ranges suitable for 3D printing.