Penetration of cement pastes into sand packings during 3D printing: analytical and experimental study
Penetration of cement pastes into sand packings during 3D printing: analytical and experimental study
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DOI：
10.1617/s11527-018-1148-5
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发表时间：
2018-02-01
影响因子：
3.8
通讯作者：
Lowke, Dirk
中科院分区：
文献类型：
--
作者：
Pierre, Alexandre;Weger, Daniel;Lowke, Dirk
混凝土和水泥基材料的3D打印工艺可以带来建筑业的建筑和结构创新。土木工程中的添加制造和数字制造方法最近在实验室规模上得到了发展。在3D打印过程中，可能会为创新和设计的建筑元素带来新的视角，其中最有趣的一种被称为选择性粘贴侵入方法。通过使用3D打印机喷嘴将水泥浆体选择性地施加在集料包装上并随后将该浆体渗透到集料层中，逐层地构建该组件。选择性膏体注入方法的可实施性要求预测屈服应力流体在多孔介质中的流动。水泥浆体的流变性必须适应其通过集料颗粒填充的多孔网络的渗透。足够的水泥浆体渗透深度可产生能够承受高机械应力的均匀材料。本文指出，用这种技术制造的构件的抗压强度与水泥浆体对集料层的渗透深度直接相关，因此，本文旨在预测水泥浆体对砂层的渗透深度。建立了一个理论框架，提出了作为平均砂粒直径和水泥浆体屈服应力的函数的渗透深度的评估，并通过具体的渗透测量进行了实验验证。最后，我们强调，用解析模型预测渗透率是确保采用3D打印选择性粘结方法构建均匀的水泥基材料的有效技术。
3D printing processes of concrete and cement based materials could bring architectural and structural innovation in construction industry. Additive manufacturing and digital fabrication methods in civil engineering have recently been developed at laboratory scale. Among the 3D printing processes that could bring new perspectives in innovative and designed architectural elements, one of the most interesting is called the selective paste intrusion method. The component is built layer by layer by selectively applying cement paste on an aggregate packing using a 3D printer nozzle and a subsequent penetration of the paste into the aggregate layer. The implementability of the selective paste intrusion method requires the prediction of the flow of a yield stress fluid through a porous media. The rheological behaviour of the cement paste must be adapted for its penetration through the porous network of the aggregate particle packing. An adequate penetration depth of the cement paste produces homogeneous materials that are capable of sustaining a high mechanical stress. We show in this paper that the compressive strength of component made by such a technique is directly linked to the penetration depth of the cement paste into the aggregate layer; consequently, this paper aims at predicting the penetration depth of cement pastes into sand layers. A theoretical framework has been developed to propose an evaluation of penetration depth as a function of the average sand grain diameter and the yield stress of the cement paste, which is experimentally validated with specific penetration measurements. Finally, we stress that the prediction of penetration with an analytical model is an effective technique to ensure building homogeneous cement based materials with the 3D printing selective binding method.