Conference Paper

Design considerations due to scale effects in 3D concrete printing

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Abstract

The effect of scale on different parameters of the 3D printing of concrete is explored through the design and fabrication of a 3D concrete printed pavilion. This study shows a significant gap exists between what can be generated through computer aided design (CAD) and subsequent computer aided manufacturing (generally based on CNC technology). In reality, the 3D concrete printing on the one hand poses manufacturing constraints (e.g. minimum curvature radii) due to material behaviour that is not included in current CAD/CAM software. On the other hand, the process also takes advantage of material behaviour and thus allows the creation of shapes and geometries that, too, can't be modelled and predicted by CAD/CAM software. Particularly in the 3D printing of concrete, there is not a 1:1 relation between toolpath and printed product, as is the case with CNC milling. Material deposition is dependent on system pressure, robot speed, nozzle section, layer stacking, curvature and more-all of which are scale dependent. The paper will discuss the design and manufacturing decisions based on the effects of scale on the structural design, printed and layered geometry, robot kinematics, material behaviour, assembly joints and logistical problems. Finally, by analysing a case study pavilion, it will be explored how 3D concrete printing structures can be extended and multiplied across scales and functional domains ranging from structural to architectural elements, so that we can understand how to address questions of scale in their design.

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... One problem is particle segregation in the hose which can lead to blockages caused by mix design and/or insufficient mixing prior to pumping. 3DCP is particularly sensitive to pauses in the build process 85 because components are created through the sequential layering of materials which must bond to form a homogeneous component, thus there is greater potential to form cold joints between layers than in more conventional casting methods [14]. ...
... A limiting factor effecting print speed, however, is the rate material can be deposited when undergoing 130 a change in direction, as illustrated in [14]. The extrusion nozzle path (tool path) can never be, in all but the rarest of cases, only linear and hence direction changes are inevitable. ...
... The extrusion nozzle path (tool path) can never be, in all but the rarest of cases, only linear and hence direction changes are inevitable. Several factors limit the speed: inertia of the extruded material; limitations of the position apparatus, such as inertia in gantry systems [21] and point-to-point interpolation issues with robotics [14]; cycle-time between layers resulting in changes in material properties and hence the pumping and extrusion characteristics of the process; and geometrical 135 imperfection during the layer deposition which causes distortion in the extruded material, often through changes in the height between layers, which effects the shape of the extrusion [22,23]. The design and creation of the tool path is therefore dependent on the material properties, the process characteristics and the size, shape and hardened properties of the component/element being manufactured. ...
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Large-scale additive manufacturing processes for construction utilise computer-controlled placement of extruded cement-based mortar to create physical objects layer-by-layer. Demonstrated applications include component manufacture and placement of in-situ walls for buildings. These applications vary the constraints on design parameters and present different technical issues for the production process. In this paper, published and new work are utilised to explore the relationship between fresh and hardened paste, mortar, and concrete material properties and how they influence the geometry of the created object. Findings are classified by construction application to create a matrix of issues that identifies the spectrum of future research exploration in this emerging field.
... Regarding the manufacturing dependent factors, one of the main limitations is the difficulty of depositing the material with a certain standard of quality while undergoing a change in direction [32], especially at high printing speed. There are also other related aspects such as the inertia of the extruded filament and the printing system, limitations of the printer itself, and the distortion of the filament due to the layer deposition and other robotic limitations [2,27,[32][33][34]. ...
... Regarding the manufacturing dependent factors, one of the main limitations is the difficulty of depositing the material with a certain standard of quality while undergoing a change in direction [32], especially at high printing speed. There are also other related aspects such as the inertia of the extruded filament and the printing system, limitations of the printer itself, and the distortion of the filament due to the layer deposition and other robotic limitations [2,27,[32][33][34]. Thus, a clear dependency relation is observed between the fresh material properties and the process of extrusion itself. ...
Article
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... to the pauses in the build process [155]. Positive-displacement pumps are frequently utilized for 3D concrete printing. ...
... For rectangular nozzles (40 mm  10 mm), the speed between 30 and 35 mm/s have been reported [124], whereas for circular nozzles of 9 mm diameter, the reported speed was in the range of 50-66 mm/s based on a gantry positioning system [166]. One of the constraints affecting print speed is the depositing rate of material when a change in direction occure [155]. Rarely the extrusion nozzle path (tool path) is linear, hence direction changes are inevitable. ...
... References.83,130,135,138,139,141,145,147,149,151,152,156,157,159,162,164,[171][172][173]175,[177][178][179][180][181][182] 88,98,102,130,135,136,139,141,142,148,150,152,154,156,157,[159][160][161][162][164][165][166]168,171,172,[176][177][178][179][180][181][182][183][184][185] [1,36,38,40,54,59,61,62,70-72,77,80,83- 85,88,130,135,136,138,143,145,146,148,152,157,158, 160,161,163,165,167,169-173,175,176,178,180,181,183] ...
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In the last few years, scattered experiences of the application of additive manufacturing in the construction of buildings using 3D printing with robots or automated equipment have emerged around the world. These use a variety of procedures and suggest relevant advantages for the construction industry. In order to identify the different processes and features in development in this field and to guide future research and applications, this article presents a review of the literature on the main aspects involved in the use of 3D printing in the construction sector. The review includes state-of-the-art material mixtures, printing technologies, and potential uses, as well as a novel analysis of building strategies, management systems, and benefits stated about this new approach for construction. It reveals progressive experimentation regarding diverse features, with challenges related to the consolidation of procedures and this technology’s readiness to participate in the building market.
... Researchers have also recognized that different problems occur at different scales. Small-scale prototypes can provide insights for mesoscale toolpath design considerations, but full-scale constructions present their unique challenges (Ahmed et al., 2016). ...
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... However, 3DAC also requires the formation of uniform layers through sequential layering of the cementitious mixture. Because there is a high possibility of cold joints being formed between layers (as compared to the traditional concrete casting method), pausing the layering process is not ideal [30]. ...
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The primary purpose of this study was to investigate the feasibility of applying polymeric cementitious materials to three-dimensional additive construction (3DAC). Specifically, styrene–butadiene rubber (SBR) latex was employed as an admixture to produce SBR-modified cementitious mixtures, and their fresh properties were experimentally investigated to determine the feasibility of their use in the 3DAC process. The SBR/cement ratio was controlled based on four main materials (i.e., cement, sand, silica fume, and fly ash) in order to determine the optimal fresh properties. The test results revealed that the SBR-modified cementitious mixtures showed excellent flowability, extrudability, buildability, and open time, all of which are required for 3DAC materials. The optimal flow of the SBR-modified cementitious mixtures was 70% ± 1%, which is appropriate for 3DAC applications. According to the experiment results, the SBR-modified cementitious mixtures were sufficiently competitive to serve as a new class of materials for 3D additive construction.
... This would lead a new paradigm of construction allowing users to perform construction based on their own ideas by simple manufacturing and production systems. Also, the construction period and cost can be greatly reduced without going through unnecessary manufacturing steps (Lee2017; Kim 2017; Ahmed et al. 2016). ...
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This study deals with (a) the development of a prototype 3D printer for concrete structures having a bed size of 1 × 1 × 1 m for a laboratory testing and (b) laboratory testing of cementitious materials with different design mixes to find their suitability and efficacy for the developed 3D printer. In this printer, a program with the concept of computer numerical controlled milling was adopted to control the nozzle motion using an easy graphic user interface program. The experiment was carried out to test mechanical control and proper material properties of the printer. Thus, the optimum values of water-cement ratio of cementitious materials for the 3D concrete printer were determined by experimental trials. Also, the adequate viscosity of the material for layering and dispensing is determined by a slump-flow test. The suitable size of sands for the dispensing system was found through the trials. However, shrinkage cracks occurred during the hardening process for the paste and mortar that polyvinyl alcohol fibers are added to prevent the cracking and build an improved quality 3D printed structure. After suitable and efficient mix ratio is found, compressive strength is measured for the mechanical property. The experiments demonstrated possibility of printing concrete structure using the 3D printer.
... 3D printing is driving major innovations in many areas, including aeronautics, medicine (Bartolo et al., 2012;Chia and Wu, 2015;Kang et al., 2016;Rengier et al., 2010), manufacturing and engineering (Doubrovski et al., 2011;Leutenecker-Twelsiek et al., 2016;Postiglione et al., 2015;Shahrubudin et al., 2019;Sossou et al., 2018;Yao et al., 2017;Zhang et al., 2016), art (Séquin, 2015;Balletti et al., 2017;Mitterberger and Derme, 2019;Derme and Mitterberger, 2020), education (Kostakis et al., 2015;Wood et al., 2017), building (Ahmed et al., 2016;Duballet et al., 2017), food (Godoi et al., 2016;Sun et al., 2015;Vancauwenberghe et al., 2017), and especially in customized production (Asadollahi-Yazdi et al., 2016). Nevertheless, soil science is a recent field of application of 3D printing and further development and application should impact the way researchers study soils within their ecosystems (Hu and Jiang, 2017). ...
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... Further consideration is needed to be given to the radii of the curves (Ahmed et al., 2016). Depending on the sharpness of the curve, the print speed decreases temporarily owing to the robot kinematics. ...
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The current state of research and development into the additive manufacturing of concrete is poised to become a disruptive technology in the construction industry. Although many academic and industrial institutions have successfully realised full-scale structures, the limitations in the current codes of practice to evaluate their structural integrity have resulted in most of these structures still not being certified as safe for public utilisation and thus deemed as test prototypes for display purpose only. To realise a 3D concrete printed (3DCP) structure which could be certified safe for public use, a bridge was realised using the print facility of the Eindhoven University of Technology (TU/e) based on the concept of ‘Design by Testing’. This paper holistically discusses the complications encountered while realising a reinforced 3DCP bridge in a public traffic network and decisions taken to find solutions for overcoming them.
... In 3DCP the effects of material and scale affect the printing results in different ways, and their inter-relationships are often the cause of unforeseen failures due to limited dimensional accuracy or mechanical performance [8,9]. Consequently, 3DCP requires custom design strategies for specific manufacturing and material processes [10,11]. Recent research has investigated developing software for controlling the printing process with different approaches. ...
Chapter
The recent advances in 3D Concrete Printing (3DCP) greatly impact architectural design, highlighting the disconnection between digital modelling and manufacturing processes. Conventional digital design tools present limitations in the description of a volumetric object, which is constrained to the definition of idealized external boundaries but neglect material, textural, and machinic information. However, 3DCP is based on material extrusion following a programmed toolpath, which requires custom modelling and methods to anticipate the manufacturing results. The paper presents the development of an interactive tool for the preview of 3D printing toolpaths within Grasshopper. Through an experimental campaign and analysis of material results, we integrate geometric, physical and design feedback within the design process. The accurate control of manufacturing variables such as printing speed and dimensions of the layers, together with the simulation and visualization of the results, makes them design parameters, opening to new formal and structural articulations in the design process. The developed instruments are tested on full scale printed prototypes, where their precision is demonstrated. Integrated into a 3DCP-specific design framework, the overall approach contributes to closing the existing gap between the digital environment and fabrication procedures in the construction industry.
... Debates remain over whether 3D printing reduces the number of traditional processes in the building, resulting in a more simplified construction and manufacturing system that saves time and money [71]. This perception could lead to a new building model that would allow concern to use basic manufacturing and production systems based on their own ideas while considerably reducing construction time and cost without unnecessary production phases [72,73]. Researchers also showed that low-temperature printing of concrete causes printability problems (such as stability during printing) [74]; thus, the rapid setting of magnesium phosphate-based cement makes it an attractive alternative to concrete printing because it greatly increases printability, design freedom, and form retention without change. ...
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... The material moves from the hopper to the extruder through a concrete pump in a conventional extrusion-based 3DCP, and the printer deposits the material by regulating the extruder's movement. The substance must have a low viscosity during pumping, as seen in this process flow [16]. It must have a high yield stress after deposition in order for the extruded layers to be stable and buildable. ...
Article
Full-text available
The construction industry is moving closer to 3D printing in concrete for the manufacture of architectural or building components. Construction Industry is expected to drastically modify current processing methods and perhaps lead to disruptive technologies for instance 3D concrete printing (3DCP), resulting in significant variations in the construction industry. Around the world, the construction industry and research initiatives are concentrating on automated construction technologies. There have been several technologies for 3DCP of concrete elements developed, and their use in building projects is increasing. 3DP's growth isn't confined to Earth; it's also gaining traction as a means of constructing space habitats. 3DCP allows for freeform building without the need for costly formwork, which has several advantages over the traditional method of pouring concrete into a formwork. In recent years, several 3DCP technologies have been created. Techniques and procedures that have been tested include on-site and off-site manufacturing of building components employing industrial robots, gantry systems, and tethered autonomous vehicles. This article presents the current state-of-the-art in the subject of 3D printing of buildings and construction components. The purpose of this research is to describe the technical, socioeconomic, and environmental components of 3DCP of concrete structures in order to provide a comprehensive overview of the 3DCP technology, applications, challenges, and future research and market opportunities in the construction sector. This research focuses mostly on current breakthroughs in 3D concrete printing, as well as other research and development projects in this subject, notably its use in alien habitats. There are several advantages to using this strategy, including cost and time savings, decreased pollutants, and a reduction in accidents and fatalities on construction sites. Despite the various benefits and prospects, the results raise certain concerns, owing to the technology's existing limitations. According to this comprehensive review, researchers should examine the challenges such as on-site fabrication, large scale manufacturing process and limitations of 3D concrete printing further in order to increase mechanical performance, durability, and sustainability, as well as create appropriate standard criteria for printing structures.
... The paradigmatic shift in the production of concrete elements to additive solutions poses the need for novel, application-specific design methods that fully control and exploit the technology potential. In spite of similarities with Fused Deposition Modelling (FDM), 3DCP requires ad hoc design methods that account, for instance, for the reduced overhangs allowed, the larger scale-and material-dependent approximations of sharp geometries, the need for reduction and minimisation of travel moves, i.e. the movements of the motion system without printing, and local control of the layer width along the toolpath [12]. ...
Article
Full-text available
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Chapter
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In this paper, the fundamentals of a 3D nested construction method for 3D-printing stackable tower-like structures are explained, taking into consideration the transportation, storage, assembly, and even disassembly of building components. The proposed method is called “PRINT in PRINT.” This paper also documents the authors’ experience of and findings from designing and printing a column erected out of a series of 3D printed components in a short stack. Employing the design principles of 3D printing in a nested fashion, the authors showcase the main parameters involved in dividing the column’s global geometry into stackable components. By converting formal, technical, and material restrictions of a robotic-assisted 3D printing process into geometric constraints, the paper describes how the column components are divided, namely that one component shapes the adjacent one.
Chapter
Case study projects based on Digitally Fabricated Concrete (DFC) are presented in an increasing pace around the globe. Generally, though, it is not reported what structural requirements (if any) these structures meet and how compliance to these requirements was established. Published material research is often not connected to the presented case studies, and even when it is, it is not necessarily obvious their small scale results can be applied to full scale structures as some scale effects should be anticipated. Caution is required as DFC related material tests are still under development and scale effects in DFC have hardly been studied. Therefore, it is recommendable to perform large scale testing, in the range of 1:5 to 1:1, if DFC is applied to actual use structures. This paper presents such testing for two projects, a pavilion in Denmark (not realized) and a bridge in the Netherlands (realized). In both cases, elements printed with the 3D Concrete Printing facility of the Eindhoven University of Technology were intended for actual load bearing performance. The conservative designs past the test requirements, but nevertheless some important findings with regard to element manufacturing and structural behaviour were experienced. It is concluded that large scale testing remains advisable for DFC structures as long as not all relevant aspects of the technology are quantitatively understood, at least when new concepts are being applied.
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As 3D printing emerging to be a much-matured technology, its range of uses are now seemed to be infinite. 3D printing is now beyond the stage where it was only observed as a prototyping solution. From a simple artwork and playing toys to ready to live in buildings and also transplantable organs, the technology could potentially last until our imaginations die. From automobile to consumer goods manufacturing industries, organizations across various industries are trying to observe the advantages 3D printing has got to offer for production. With such acknowledgements, organizations are now trying to find their ways to incorporate this technology in their respective industries, whose applications could potentially extend from tooling to spare/replacement parts and sometimes till a full-fledged end-use ready product. While 3D printing looks like a most exciting new normal for organizations who are planning to streamline their prototyping technology, its prospects for the non-tech consumer world is also evolving rapidly. Additive Manufacturing in construction can be seen as an option that could contribute towards complete automation in the infrastructure industry. The method offers advantages in the aspects of design, sustainability and also efficiency. This work scopes for a comprehensive approach to advance the technology in construction and proposes research potentials, challenges, and future scope. The potential of 3dcp for automation advances all other practices in prospects like exclusion of form work, precise design execution, waste reduction and extremely low consumption of time. The real-time status and futuristic approaches to be adopted are briefed in the paper and also the scope for sustainability over other practices are detailed in the paper.
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Additive manufacturing is gaining ground in the construction industry. The potential to improve on current construction methods is significant. One of such methods being explored currently, both in academia and in construction practice, is the additive manufacturing of concrete (AMoC). Albeit a steadily growing number of researchers and private enterprises active in this field, AMoC is still in its infancy. Different variants in this family of manufacturing methods are being developed and improved continuously. Fundamental scientific understanding of the relations between design, material, process, and product is being explored. The collective body of work in that area is still very limited. After sketching the potential of AMoC for construction, this paper introduces the variants of AMoC under development around the globe and goes on to describe one of these in detail, the 3D Concrete Printing (3DCP) facility of the Eindhoven University of Technology. It is compared to other AMoC methods as well as to 3D printing in general. Subsequently, the paper will address the characteristics of 3DCP product geometry and structure, and discuss issues on parameter relations and experimental research. Finally, it will present the primary obstacles that stand between the potential of 3DCP and large-scale application in practice, and discuss the expected evolution of AMoC in general.
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We present a fully functional material extrusion printer for optically transparent glass. The printer is composed of scalable modular elements able to operate at the high temperatures required to process glass from a molten state to an annealed product. We demonstrate a process enabling the construction of 3D parts as described by computer-aided design models. Processing parameters such as temperature, which control glass viscosity, and flow rate, layer height, and feed rate can thus be adjusted to tailor printing to the desired component, its shape, and its properties. We explored, defined, and hard-coded geometric constraints and coiling patterns as well as the integration of various colors into the current controllable process, contributing to a new design and manufacturing space. We report on performed characterization of the printed materials executed to determine their morphological, mechanical, and optical properties. Printed parts demonstrated strong adhesion between layers and satisfying optical clarity. This molten glass 3D printer demonstrates the production of parts that are highly repeatable, enable light transmission, and resemble the visual and mechanical performance of glass constructs that are conventionally obtained. Utilizing the optical nature of glass, complex caustic patterns were created by projecting light through the printed objects. The 3D-printed glass objects described here can thus be extended to implementations across scales and functional domains including product and architectural design. This research lies at the intersection of design, engineering, science, and art, representing a highly interdisciplinary approach.
The Future of The Professions
  • R S A D Susskind
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3D printing of sustainable concrete structures
  • R J M Wolfs
  • T A M Salet
  • L N Hendriks
Wolfs, R.J.M., Salet, T.A.M., and Hendriks, L.N., 2015. 3D printing of sustainable concrete structures. Proceedings of the International Association for Shell and Spatial Structures (IASS) Symposium 2015, Amsterdam. yhbm.com, 2016 Available from: http://www.yhbm.com/index.php?a=lists&c=index&catid=67&m=content [Accessed June 2016].