Experimental and Numerical Assessment of Layer Deformation in a 3D Printed Concrete Element

3D concrete printing is a new and pioneering construction method that involves fabricating an element by depositing concrete layers according to a predetermined virtual model. This technology allows for faster construction and fabrication of customizable and complex shapes. In this study, a 3D printable concrete mix was developed using Portland cement and fly ash (80:20 by mass) as the binder. The rheology of the mixtures (yield stress and plastic viscosity) was characterized by performing flow curve experiments using a dynamic shear rheometer. To assess the buildability of the mix, a three-layer filament of 300 mm length was printed using a circular nozzle of 20 mm diameter. A digital camera was also used to record the print experiment, and subsequently, the deformation of each layer was determined using image analysis. Finally, using the measured rheological parameters, a fluid-based FEM numerical model was adopted to simulate the printing process. The filament shapes obtained from the simulation were compared to those obtained from the actual print experiment. Both numerical simulation and image analysis indicated that the layer deformation is evident. The results from the numerical simulations agreed well with the experimental results.