Mechanical Characterization of Cement-Based Mortar Used in 3DCP Including Early-Age Creep Effects (2020-07)¶

Digital fabrication techniques combined with suitable cementitious materials have successfully led to the implementation of innovative manufacturing processes for concrete-like products. However, although significant advantages are expected in layered extrusion (LE) concrete technology, manifold engineering challenges arise from the process itself, such as the full control of the mechanical properties evolution during printing. Primarily, printed materials should satisfy specific early-age mechanical and rheological requirements, whose definition remains unstandardized. Additionally, scarce literature on testing procedures for early-age printable mortars is currently available. In this paper, uniaxial compressive tests are performed on cylindrical samples to determine the time-dependent compressive behavior and the early-age creep effects on fresh concrete. The load application conditions are varied in the experimental campaign in order to propose a proper mechanical characterization procedure for 3D printable cementitious mortars. Finally, results are implemented in an analytical model to predict the accumulated creep strain during the printing process. The outcomes highlight the role of the early-age creep in the development of global deformations.