Identifying interlayer fracture properties in 3D printed concrete specimens via multidirectional flexural tests

3D printing of concrete presents the new challenge of anisotropy to an already heterogenous medium of concrete. The layer-wise mode of construction quintessential to the printing of concrete leaves interfaces which have different properties to that of the layer. These interfaces interact and interfere with crack propagation compared to monolithically cast specimens and contribute to differential properties of structural elements in different directions. This phenomenon is identified by performing 3-point bending tests on printed elements with different layer orientations and comparing the fracture energy in Mode I (Gf) and peak flexural stresses (s f) of the printed concrete tested. Subsequently, ABAQUS model of 3-point bending tests are developed with different material properties of the interface elements and the layers which are validated against the experimental results. Upon parametrisation of the fracture energy and peak flexural stress values, it has been noted that the properties of the interface elements are categorised by the tests done with the loading direction parallel to the layer orientation.