Flexural behaviour of AR-glass textile reinforced 3D printed concrete beams

3D concrete printing (3DCP) enables automation of construction manufacturing through digital design and workflow, adding value through high degrees of form freedom. The process constraints during the printing, however, hamper the application of reinforcement and hence limit the ductile behaviour that is achievable in 3D printed concrete structures. Although a number of reinforcement strategies have been developed and these strategies can to some extent address these limitations, the reinforcement challenges of 3D printed concrete structures are not satisfactorily addressed yet. This paper proposes another reinforcement strategy of incorporating alkali-resistant (AR)-glass textile between the printed concrete layers. To validate the strategy, small-scale printed concrete beam specimens reinforced with one to three layers of textiles were tested under three-point bending. The results were compared to those obtained from equivalent ‘cast’ specimens. Comparable flexural behaviours were observed between the cast and printed textile reinforced concrete (TRC) specimens. Moreover, the flexural behaviours of printed specimens exhibited lower scatter than the flexural behaviours of cast specimens, which was probably due to the precise digitally controlled printing process. Future research should focus on the application of textile reinforcement in more complex 3D printed concrete structures

Inspecting manufacturing precision of 3D printed concrete parts based on geometric dimensioning and tolerancing

The additive manufacture of parts using extrusion-based techniques such as 3D Concrete Printing (3DCP) offers an alternative to traditional moulding processes. The precision to which the desired shape can be produced, however, is limited by the extrusion process and layer thickness, exacerbated by the deformation that occurs in the wet material during manufacture. Quantifying manufacturing precision is a critical part of defining process capability and quality control procedures, but this has yet to be explored for these technologies. To address this, this paper presents the problem of evaluating the geometrical precision of manufactured parts and then proposes an approach based on geometric dimensioning and tolerancing (GD&T), commonly used in manufacturing. This is then applied in a case study in order to demonstrate the application of the technique for understanding and defining process capability, to enable more effective design rules that lead to greater confidence in the viability of part designs, and to provide the reliable performance metrics necessary for process improvement and control. The work concludes that the outlook for such techniques is positive and that the application will be beneficial in the future development of quality control procedures for 3DCP