Vibration-Assisted Rheological Control for 3D Printing of Precast Concrete Modules (2025-12)¶

Construction automation is expected to address challenges in the construction industry. One of the key enablers of automation is the ability to control the rheological behavior of cementitious materials. Additive manufacturing, among various attempts to implement automation in construction, shows promise for optimizing construction processes and enhancing workflow efficiency. Nevertheless, 3D concrete printing has faced several technical challenges including weak layer-to-layer bonding and difficult arrangement of reinforcing bars. This study introduces a precast concrete module printing approach to mitigate these limitations by utilizing highly flowable concrete without pumping. A miniature printing system equipped with L-shaped channel and nozzle was used to evaluate the printing performance. Mortar mixtures incorporating different dosages of polycarboxylate ether exhibited different waiting times of 4-25 min to reach the yield stress. Printing tests demonstrated that vibration improved the printing length. For Sample A0 and A1, the printing length increased at 3.6 V and 1.8 V voltage of vibration, respectively, thereby expanding the printable region compared with the non-vibration condition. By controlling the thixotropy of the material through waiting-at-rest and vibration, the concrete can be printed while maintaining shape stability. The controlled thixotropic behavior prevents both plastic failure of the printed material and clogging in the delivery system. The proposed approach provides a viable pathway for developing alternative printing strategies for construction automation.