Novel Strategy for Enhancing Rheological Properties and Interlayer Bonding in Underwater 3D Concrete Printing (2025-04)¶

The emergence of underwater 3D concrete printing (U3DCP) technology has brought forth novel methods for the construction and repair of submerged structures. The conventional practice in U3DCP adding anti-washout admixtures (AWAs) will lead to cross-effects among various working properties of the printing materials and contradictory issues between performance, which may also be one of the obstacles that hinder the progress of U3DCP in-site applications. Hence, this paper presents a novel strategy for printing concrete in an environment containing underwater seepage inhibitor (USI) without adding AWAs into concrete. The findings indicate that the novel U3DCP possesses lower yield stress and plastic viscosity along with greater thixotropy than the traditional U3DCP. Moreover, it can significantly reduce or even eliminate the risk of surface cracking when printing fresh U3DPC. And the concrete printed in low-dose USI has better interface bonding and compressive strength, interpreted from a microscopic perspective via FIRT and SEM analysis. Furthermore, the rheological properties and interlayer bonding of the novel U3DCP are analyzed using grey relational analysis (GRA), and it is discovered that the flowability of U3DPC is highly correlated with its interface bond strength.