Constitutive response and failure progression in digitally fabricated (3D printed) concrete under compression and their dependence on print layer height
Constitutive response and failure progression in digitally fabricated (3D printed) concrete under compression and their dependence on print layer height
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DOI：
10.1016/j.conbuildmat.2023.134246
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发表时间：
2024-01
影响因子：
7.4
通讯作者：
Sooraj A.O. Nair;Avinaya Tripathi;N. Neithalath
中科院分区：
文献类型：
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作者：
Sooraj A.O. Nair;Avinaya Tripathi;N. Neithalath
在决定3D打印混凝土最终产品质量的几个几何形状和工艺相关特征中，具有相当重要意义的一个特征是各个层的高度/厚度。对于给定的混合物和打印机特性，层高度决定了层间界面的数量，并影响层和界面（层间和丝间两者）的性质。本文研究了层高度对3D打印混凝土试件在压缩条件下的本构响应和破坏的影响，研究了沿着层堆积方向（或垂直于层界面），这是3D打印墙和柱的主要加载平面。打印了两种不同层高（7.5 mm和15 mm）的普通和钢纤维增强墙元件，从中提取并测试了圆柱形和棱柱形试样。单轴抗压强度随着层高度的增加而降低。具有不同层高度的试样的本构关系，沿着与体积应变，使提取的裂纹起始应力和不稳定的裂纹扩展应力，这是受层高度和纤维增强体的存在。失稳裂纹扩展应力低于峰值应力，且随层高的增加而减小。数字图像相关（DIC）是用来证明占主导地位的影响，丝间界面上的裂纹扩展响应和由此产生的故障。
Among the several geometry and process-related characteristics that determine the ultimate product quality of 3D printed concrete, one that has gained considerable importance is the height/thickness of the individual layers. Layer height dictates the number of interlayer interfaces, and influences the properties of the layer and the interfaces (both interlayer and inter-filament), for a given mixture and printer characteristics. This paper examines the influence of layer height on the constitutive response and failure of 3D printed concrete specimens under compression, investigated along the direction of layer build-up (or perpendicular to the layer interfaces), which is the dominant plane of loading in 3D printed walls and columns. Plain and steel fiber-reinforced wall elements with two different layer heights (7.5 mm and 15 mm) are printed, from which cylindrical and prismatic specimens are extracted and tested. The uniaxial compressive strength is seen to decrease with increasing layer height. The constitutive relationships of the specimens with different layer heights, along with volumetric strains, enable the extraction of crack initiation stress and unstable crack propagation stress, which are influenced by layer height and the presence of fiber reinforcement. The unstable crack propagation stress is lower than the peak stress, and it decreases with increasing layer height. Digital image correlation (DIC) is used to demonstrate the dominant effect of inter-filament interfaces on the crack propagation response and resultant failure.