Evaluation of the unconfined uniaxial compression test to study the evolution of apparent printable mortar properties during the early age transition regime

The aim of this study is the evaluation of the unconfined uniaxial compression test (UUCT) to study the evolution of the apparent material properties of the printable mortar during the early age transition regime between the non-Newtonian fluid and the cohesive frictional material. For this application it is important to establish validated and reliable test procedures. The main focus lies on the determination of the apparent static Young's modulus, which defines limitations for stability failure of 3D printed structures. The results of UUCT beyond the apparent elastic range help to better distinguish between ductile and brittle behavior. A numerical simulation of the UUCT by the Mohr-Coulomb material model with apparent material properties determined by UUCT and direct shear test is able to reproduce the behavior at different ages, including material stiffness and deformation patterns, which is considered as an additional validation of the test procedure.