Research on the Preparation and Mechanical Properties of Solidified 3D Printed Concrete Materials

Three-dimensional (3D) printing is an innovative manufacturing process based on 3D digital models that involves layer-by-layer addition of materials. In recent years, 3D printing has made good progress in the field of construction, thereby leading to more stringent requirements for materials. In this study, we first compare different equipment and materials used for 3D printing concrete. Subsequently, the mix ratio of extruded and cured 3D printed concrete is studied by using flow and slump as the main evaluation indexes. Through a universal test, the influence of different dosages of water reducer, retarder, and latex powder on the performance of 3D printed concrete (compression resistance strength) is studied. Furthermore, the optimum mix ratio for fiber reinforced concrete is determined, based on which axial pull-out, axial compression, and three-point bending tests are performed to elucidate the peak compressive strength, load–displacement curve, and mechanical properties of 3D printed concrete. By employing the ABAQUS finite element software, the shaft pulling force and axial compression of 3D printed concrete are simulated and analyzed to determine the parameters influencing the bonding performance of different 3D printed concrete layers. Moreover, the influence of water reducer and sand–glue ratio is observed to be greater than that of water gel ratio and sodium gluconate. The testing results showed that the mechanical strength of 3D printed concrete is lower than that of poured concrete. Meanwhile, bending and compressive strengths of 3D printed concrete and poured concrete are quite different.