ABSTRACT

The rapid development of additive manufacturing of cementitious materials has enabled the emergence of a new design paradigm, namely functional grading of material properties by location. Target performance parameters could be material weight and insulation value or (particularly important) ductility. A generic concept to achieve this, is through the selective addition of fibres or aggregates. In 3D concrete printing (3DCP), this concept can be developed into two strategies: by adding particles (i) to the bulk mixture through a second stage mixing process at the printer head (Simultaneous Process, SP), or (ii) in between the layers of deposited cementitious filament (Repetitive Sequential Process, RSP). The present paper presents the development of specific equipment required to obtain on–demand functional grading of the printed material. Subsequently, the application of these systems in print trials is shown. The current study focussed on ductility by creating fibre–reinforced 3D printed concrete through both strategies. The mechanical performance of the obtained material has been established through compressive, flexural, and crack–mouth opening displacement tests. To underline the generic nature of the strategies, a trial with lightweight aggregates has also been performed. It was shown that particularly the SP is capable of achieving improvements in ductility and self–weight.

摘要

胶结材料增材制造的快速发展使得出现了一种新的设计范式，即按位置对材料特性进行功能分级。目标性能参数可以是材料重量和绝缘值或（特别重要的）延展性。实现这一目标的通用概念是通过选择性添加纤维或聚集体。在3D混凝土打印（3DCP）中，该概念可以发展为两种策略：通过在打印机头的第二阶段混合过程（Simultaneous Process，SP）将颗粒（i）添加到本体混合物中，或（ii）沉积的胶凝丝层（重复顺序过程），RSP）。本白皮书介绍了获得印刷材料按需功能分级所需的特定设备的开发。随后，显示了这些系统在印刷试验中的应用。当前的研究集中在通过两种策略创建纤维增强的3D打印混凝土上的延性。所得材料的机械性能已通过压缩，弯曲和裂口张开位移试验确定。为了强调该策略的通用性，还进行了轻量级骨料的试验。研究表明，SP尤其能够改善延展性和自重。