Rheology assessment of mortar materials for additive manufacturing

This review article discusses the relevant rheological tests to evaluate the properties of compositions applied to the 3D printing of concrete (3DCP). These materials must rapidly develop rigidity and resistance, avoiding the collapse of the printed structure, with suitable buildability and other state properties, such as extrudability. A good balance must be maintained between properties and rheological parameters, such as yield stress and viscosity. Cohesion, Young's modulus, and thixotropy are also among the parameters used in these evaluations. The rheological tests addressed are the rheometer, direct shear test, uniaxial unconfined compression test, and penetration test. Their limitations must be taken into account to obtain accurate values of the rheological parameters. It was found that the most used test is the rheometer, and the test that needs to be further studied is the penetration test. Hence, it is recommended to search for a more expeditious method related to the rheological assessment to facilitate obtaining the associated parameters in a simple way.