Expansive cementitious materials to improve micro-cable reinforcement bond in 3D concrete printing
Expansive cementitious materials to improve micro-cable reinforcement bond in 3D concrete printing
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DOI：
10.1016/j.cemconcomp.2021.104304
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发表时间：
2021-10
影响因子：
10.5
通讯作者：
Zhijiang Li;G. Ma;Fangwen Wang;Li Wang;J. Sanjayan
中科院分区：
文献类型：
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作者：
Zhijiang Li;G. Ma;Fangwen Wang;Li Wang;J. Sanjayan
微缆加固已被证明是提高三维（3D）打印混凝土力学性能的一种有前途的解决方案。一般来说，同时夹带的微索与混凝土基体之间的界面粘结不足限制了微索加固的普遍应用。本文提出了一种在打印过程中自动加入膨胀胶凝材料（ecm）在电缆-混凝土界面中的方法，以改善3D混凝土打印中的电缆粘结性，提高抗裂性。在实验室中设计并开发了一种拉出装置，用于评估不同键合长度下电缆-基质的键合性能。对微索增强梁进行了四点弯曲试验。利用数字图像相关技术对试验过程中的裂纹演化进行了监测。试验数据与计算的裂缝和极限荷载、裂缝间距和裂缝宽度进行了比较，差异较小，仅为15%。实验结果表明，粘结强度提高44% ~ 67%，裂缝宽度减小30% ~ 50%，证明了该方法在提高电缆粘结性和抗裂性方面的有效性。扫描电镜观察表明，这种改善可归因于加入ecm后电缆- ecm界面的孔隙率降低或微观结构更致密。
Microcable reinforcement has been demonstrated as a promising solution for enhancing the mechanical properties of three-dimensional (3D) printed concrete. Generally, inadequate interfacial bonding between simultaneously entrained microcables and concrete matrix limits the general application of microcable reinforcement. This paper proposes a method of automatically including expansive cementitious materials (ECMs) in the cable–concrete interface in the printing process to improve the cable bond in 3D concrete printing to improve cracking resistance. A pull-out device is designed and developed in the lab to assess the cable–matrix bonding properties with respect to different bond lengths. Four-point bending tests of a microcable-reinforced beam are also conducted. The crack evolution during these tests is monitored by digital image correlation. The test data are compared with calculated cracking and ultimate loads, crack spacing, and crack width, and a small difference of 15% is found. The experimental results exhibit a 44%–67% increase in the bond strength and a 30%–50% reduction in crack width, demonstrating the effectiveness of the currently proposed method in improving both the cable bond and cracking resistance. Scanning electron microscopy observations reveal that the improvements can be attributed to the lowered porosity or denser microstructure at the cable–ECM interface realized by the addition of the ECMs.