Effect of testing procedures on buildability properties of 3D-printable concrete

Digital fabrication with concrete enables the efficient and quick creation of architectural/structural elements without formworks. This technology does, however, introduce new challenges, especially concerning the mechanical requirements of printable materials. Consequently, the mechanical characterisation of early-age printable mortar is essential for designing, controlling and modelling the printing process, but no standardised testing procedures are currently available. In this paper, the results of uniaxial compressive tests performed on cylindrical samples are compared by varying the testing procedures, with the ultimate goal being to investigate their effect on the time-dependent mechanical properties of printable mortar. Finally, the results are used to predict failure during the printing process due to self-buckling or excessive compression on the first mortar layer. The outcomes highlight the role of specimen preparation, as well as the displacement rate on the predicted critical number of layers.