Inherent weak interfaces between adjacent layers by the laminate stacking process of 3D concrete printing is one of the main hindrances of this advanced technique for general engineering application. In this paper, polymer modified mortars were fabricated to improve the weak interlayer bonding performances. The effects of setting time of the printed concrete and the change of interlayer moisture were tested. Both epoxy resin and chloroprene latex modified mortars were prepared and used as interlayer interface enhancement materials according to different interlayer intervals. The direct tensile and shear strengths of the polymer mortar strengthened interfaces were tested and evaluated by the cross-over test. Moreover, the effects of moisture released from the surface of cement-based composite materials on inter-laminar bonding properties and the enhancing mechanism of epoxy resin and chloroprene latex modified mortars were simulated through molecular dynamics (MD) and density functional theory (DFT). The results demonstrate that the electrostatic interaction (Coulomb force) between epoxy resin and calcium ions from hydrated calcium silicate (C-S-H) counteracts the weakening effect of water molecules (surface moisture) on the inter-laminar bonding, and thus improve the interface bonding of printed concrete. The constitution of the optimal polymer mortar to strength interfaces most effectively has been identified.

通过3D混凝土打印的层压堆叠过程，相邻层之间固有的弱界面是这种先进技术在一般工程应用中的主要障碍之一。本文制备了聚合物改性砂浆，以改善薄弱的层间粘结性能。测试了印刷混凝土的固化时间和层间水分变化的影响。制备环氧树脂和氯丁二烯胶乳改性砂浆，并根据不同的层间间隔将其用作层间界面增强材料。聚合物砂浆增强界面的直接拉伸强度和剪切强度已通过交叉测试进行了测试和评估。此外，通过分子动力学（MD）和密度泛函理论（DFT）模拟了水泥基复合材料表面水分释放对层间粘结性能的影响以及环氧树脂和氯丁二烯乳胶改性砂浆的增强机理。结果表明，环氧树脂与水合硅酸钙（CSH）的钙离子之间的静电相互作用（库仑力）抵消了水分子（表面水分）对层间键合的弱化作用，从而改善了印刷件的界面键合具体。已经确定了最有效地达到强度界面的最佳聚合物砂浆的组成。