The integration of reinforcement in 3D concrete printing (3DCP) presents a major challenge in current 3DCP industry. Engineered cementitious composites (ECC) with self-reinforcing characteristic provides a promising solution. However, the conflicting requirements between extrudability and buildability are amplified for 3D-printable ECC (3DP-ECC) due to the existence of a large-amount of fibers. This study investigates the printability region for 3DP-ECC based on standardized field-friendly workability test. The effects of superplasticizer (SP) dosage, hydroxypropyl methylcellulose (HPMC) dosage and fiber content on the workability and printability of 3DP-ECC at varying resting times were explored. The results of grey relational analysis (GRA) show that the workability can be regulated by SP dosage, HPMC dosage, fiber content and resting time. The workability test results in conjunction with the printability evaluation results were used to define the printable region. The suitable ranges of workability parameters including spread diameter, slump, and penetration depth for 3DP-ECC are 130–142.5 mm, 1–31 mm, and 7.5–22 mm, respectively. In addition, the hardened mechanical properties of 3DP-ECC with satisfactory printability were examined by tensile and compressive performance. This study proposes a simple but effective method for predicting the printability of 3DP-ECC and the findings provide guidance for researchers and engineers to easily develop printable ECC.

中文翻译：

---

可 3D 打印工程水泥复合材料 (3DP-ECC) 的适印区域


3D 混凝土打印 (3DCP) 中的钢筋集成是当前 3DCP 行业面临的重大挑战。具有自增强特性的工程水泥复合材料（ECC）提供了一个有前途的解决方案。然而，由于大量纤维的存在，3D 打印 ECC (3DP-ECC) 的可挤出性和可构建性之间的矛盾要求被放大。本研究基于标准化现场友好可加工性测试，研究了 3DP-ECC 的印刷适性区域。探讨了不同静置时间下超塑化剂 (SP) 用量、羟丙基甲基纤维素 (HPMC) 用量和纤维含量对 3DP-ECC 的可加工性和可印刷性的影响。灰色关联分析(GRA)结果表明，和易性可以通过SP用量、HPMC用量、纤维含量和静置时间来调节。使用可加工性测试结果与可印刷性评价结果结合来定义可印刷区域。 3DP-ECC 的施工参数（包括铺展直径、坍落度和渗透深度）的合适范围分别为 130–142.5 毫米、1–31 毫米和 7.5–22 毫米。此外，通过拉伸和压缩性能检查了具有令人满意的印刷适性的3DP-ECC的硬化机械性能。这项研究提出了一种简单但有效的方法来预测 3DP-ECC 的可打印性，研究结果为研究人员和工程师轻松开发可打印 ECC 提供了指导。