Buildings can be rapidly constructed using 3D printed concrete technology without formwork, garnering increasing attention within the construction industry. The effects of different printing parameters on the splitting tensile strength, shear strength, pore structure, and micromorphology of the interface between 3D printed ECC and post-cast concrete were investigated, including single-layer printing height, fiber content, and recycled sand replacement ratio. The results indicated that as the fiber content and single-layer printing height increased, the interfacial bond strength was initially enhanced while subsequently decreased, with optimal bond strength achieved at a 15 mm single-layer printing height. Moderate fiber content and single-layer printing height were beneficial for interfacial bond strength. Meanwhile, the interfacial bond strength was reduced due to the evolution of interfacial pore structure after the incorporation of recycled sand. The splitting tensile strength and shear strength of the interface between 3D printed ECC and post-cast concrete decreased by 36.1% and 35.8%, respectively, when the replacement ratio of recycled sand in ECC was 100%. Additionally, models for the interfacial shear strength between 3D printed ECC and post-cast concrete were proposed.

中文翻译：

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3D 打印工程水泥基复合材料 （ECC） 与后浇混凝土之间的界面粘合性能


无需模板即可使用 3D 打印混凝土技术快速建造建筑物，这在建筑行业引起了越来越多的关注。研究了不同打印参数对 3D 打印 ECC 与后浇混凝土界面劈裂抗拉强度、剪切强度、孔隙结构和微观形貌的影响，包括单层打印高度、纤维含量和再生砂替代率。结果表明，随着纤维含量和单层打印高度的增加，界面粘合强度最初增强，随后降低，在 15 mm 单层打印高度时实现了最佳粘合强度。适度的纤维含量和单层打印高度有利于界面粘合强度。同时，由于回收砂掺入后界面孔隙结构的演变，界面结合强度降低。当 ECC 中再生砂的替代率为 100% 时，3D 打印 ECC 与后浇混凝土界面的劈裂抗拉强度和剪切强度分别下降了 36.1% 和 35.8%。此外，还提出了 3D 打印 ECC 和后浇混凝土之间的界面剪切强度模型。