Article

# 3D Printing Concrete on temporary surfaces: The design and fabrication of a concrete shell structure

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

## Abstract

One of the geometrical restrictions associated with printed paste materials such as concrete, is that material must be self-supporting during printing. In this research paper a new methodology for 3D Printing Concrete onto a temporary freeform surface is presented. This is achieved by setting up a workflow for combining a Flexible Mould developed at TU Delft with a 4-degrees-of-freedom gantry printer (4 DOF) provided at TU Eindhoven. A number of hypothetical cases are studied, namely fully-printing geometries or combining 3D printing with casting concrete. The final outcome is a 5 m 2 partially-printed and partially-cast shell structure, combined with a CNC-milled mould simulating a Flexible Mould.

## No full-text available

... This makes it possible to form the loadbearing and partition walls of buildings. Printing machines (printers) are based on different kinematic solutions, and Cartesian robots [17][18][19], robotic manipulators [9,20,21], and Delta type manipulators [22,23] are used. Stay-in-place for the construction of support columns [24] or foundations [25] are also printed. ...
... C t,re f = G πl 1 D re f H re f (18) where: C t,re f -calculated parameter of skin friction mobilizing curve of the referenced pile, mm/kN; l-length of soil deflection surrounding the pile, m. Equations (17) and (18) were used to determine the function describing the susceptibility of a pile skin of any diameter D and length H on the basis of the susceptibility and geometry of the reference pile. ...
... C t,re f = G πl 1 D re f H re f (18) where: C t,re f -calculated parameter of skin friction mobilizing curve of the referenced pile, mm/kN; l-length of soil deflection surrounding the pile, m. Equations (17) and (18) were used to determine the function describing the susceptibility of a pile skin of any diameter D and length H on the basis of the susceptibility and geometry of the reference pile. ...
Article
Full-text available
Foundation piles that are made by concrete 3D printers constitute a new alternative way of founding buildings constructed using incremental technology. We are currently observing very rapid development of incremental technology for the construction industry. The systems that are used for 3D printing with the application of construction materials make it possible to form permanent formwork for strip foundations, construct load-bearing walls and partition walls, and prefabricate elements, such as stairs, lintels, and ceilings. 3D printing systems do not offer soil reinforcement by making piles. The paper presents the possibility of making concrete foundation piles in laboratory conditions using a concrete 3D printer. The paper shows the tools and procedure for pile pumping. An experiment for measuring pile bearing capacity is described and an example of a pile deployment model under a foundation is described. The results of the tests and analytical calculations have shown that the displacement piles demonstrate less settlement when compared to the analysed shallow foundation. The authors indicate that it is possible to replace the shallow foundation with a series of piles combined with a printed wall without locally widening it. This type of foundation can be used for the foundation of low-rise buildings, such as detached houses. Estimated calculations have shown that the possibility of making foundation piles by a 3D printer will reduce the cost of making foundations by shortening the time of execution of works and reducing the consumption of construction materials.
... Having started to be employed experimental method relied on empirical data, the research process ends up with the optimisation of surface accuracy and the small curvature radii. The validation is conducted either by the finite element method (FEM) (Borg Costanzi et al., 2018;Kleespies and Crawford, 1998;Koc and Thangaswamy, 2011) or experimental method in which the laboratory experiments are conducted to test the prototypes. The accuracy and precision between digital input and physical output are tested via 3D scanners (Eigenraam, 2013;Ku and Gurjar, 2018). ...
... The integrated system proposed by Loh et al. (2019) for both adjusting double-curved surfaces by CNC fixture and trimming the inaccurate edges of the cast is an example of such systems. Hybrid system with pin mould and robotic arm are proposed by Borg Costanzi et al. (2018) and Lim et al. (2020), which is preferred for achieving a uniform surface thickness via concrete printing. 3D printing is a very promising technology also when a surface pattern is printed on fabric as an ornament (Engholt and Pigram, 2019). ...
... Then, the robotic arm defines the coordinates of the panel for trimming the edges according to the deviations of the intended panel geometry. BorgCostanzi et al. (2018) combined pin-bed with concrete 3D printing to fabricate ornamented double-curved panels.Pin movements are generally vertical. ...
Article
The rigid and one-off moulds are quite insufficient to fabricate differentiated and non-standard building components due to the low adaptation capability of mass production to changing demands of the market. Aligning with mass customisation, flexible tools are developed to solve time, cost and waste problems in moulding and casting of variable building components in the architecture, engineering, and construction. This study guides architects and engineers in the development of flexible moulds and tooling for building components. This paper aims to review the latest research trends by analysing the publications from 2004 to 2019. The systematic mapping method was adopted from software engineering to determine the-state-of-the-art technologies in flexible tools. The review study shows that flexible tools can be used to cast variable and non-standard building components by further researching on large-scale implementation, process capability and control. A survey of future trends in this promising field concludes this paper.
... In fact, medieval builders had been constructing unreinforced, compression-dominated arch and vault structures by assembling masonry blocks piece by piece [5,6]. Such structural form had attracted builders' and researchers' attention because it became a self-supported structure after assembling [5,7] and needed less or no steel reinforcement [5,[7][8][9][10]. Reduction or elimination of steel reinforcement could lower the cost during construction and maintenance phase because steel reinforcement led to increased material and installation cost and was subjected to corrosion and fire-induced deterioration in concrete [9]. ...
... However, compared to particle-bed 3D printing [31], extrusion-based 3D-printing for cement/sand-based materials currently have not only higher technology readiness but also higher economic viability for rapid fabrication for building component [32]. Therefore, the extrusion-based technology is currently a more popular technology for construction 3D-printing [32,33] and was selected by many researchers as the technologies for fabricating shell and spatial concrete structures that were compressiondominated [8,12]. ...
... To deploy such an approach for 3D-printing of dome and vault structures with dimensions enlarged to about 5 m in size, the span of robotic arm needed to be scaled up accordingly. Instead of using 6-axis robot, Borg Constanzi et al. [8] sought to use a 4-axis Cartesian robots to 3D-print an unreinforced pavilion structure. In a typical 3D-printing process where concrete extrusion nozzle was moved by a 3 or 4-axis robot in horizontal plan for depositing each layer of concrete on top of a flat print bed, the 3Dprinter stacked many consecutive concrete layers covered either same or progressively reduced areas, resulting a geometry without material overhanging. ...
Article
Full-text available
Existing approaches from design to concrete 3D-printing fabrication can customize the shapes of compression-dominated concrete arches and vaults but has limited applications due to high facility requirements such as a robotic arm and a reconfigurable print bed for fabricating overhanging geometries. Therefore, there is a need to develop an alternative design-to-fabrication approach for 3D printers without such facility requirements. In this paper, concrete blocks were designed as prismatic shapes which could be customized by a most basic, gantry-based 3D printer with a flat print bed and could be assembled to a larger 3D arch structure designed based on stability and strength analyses. The feasibility of such approach was demonstrated by lab prototyping. Reduced facility requirements in this approach allow 3D-printing to be more widely applied for customizing compression-dominated structures. With further design method innovation in the future, this design-to-fabrication approach can be extended for compression-dominated structures with more complex geometries.
... This step can be critical for their design, and the previously mentioned challenges of structural continuity and watertightness remain. In the case of human handling, or machine assisted handling, of the objects, it is advisable to allow for some imprecision of the assembly step [18]. In principle, the whole handling can also be automated, but development is still needed to achieve that. ...
... Some experiments have been conducted to link concrete printing with surface support to generate shell, or shell like, geometries. The most direct of those is undoubtedly the assembled printed shell published in [18], see figure 6.3. Here the printing makes use of a CNC milled support to match the desired curvature, and generate a contour. ...
... In [18] is also mentioned the idea of doing a stress line approach with this supported printing technique, as proposed in [89]. This system could be of interest for novel structural typologies like the Trumpf foot bridge 1 visible on figure 6.4, to simplify the manufacturing. ...
Thesis
Full-text available
This work deals with a novel field of investigation for civil engineering and building industry called large scale 3D printing, or additive manufacturing, of cementitious materials. It makes use of robotic devices to progressively bring a fresh concrete or mortar into a desired shape, without using traditional formworks. The main associated ambitions are productivity and sustainability, achieved through automation and geometric complexity. Many approaches are able to succeed in correctly shaping a cementitious matter in space and ensuring its final characteristics. Among them a recent one can be called robotic extrusion, on which the present work focuses. It consist in pumping and depositing a fresh mortar, or fine concrete, relying on its early age structuration rather than on the shaping abilities of a formwork. If the physical and rheological phenomena at stake begin to be understood, there is no clear knowledge of a specific strategy yet, and many strategies are developed in parallel by the community. The first part of this work presents those, and aims at providing sufficiently distinctive definitions, see chapter 2. Three idealized approaches are proposed, differing in the history of solicitations and structuration for the printed material. Beyond the rheology oriented approach, this work seeks to broaden the scope of concrete printing and shift the discussion from materials to final building systems. Indeed, not only a construction product often includes more than just concrete, but the printing itself can be generalized to a more complete understanding. This is the ambition of a proposed classification system, presented in chapter 3. Illustrating the notion of generalized printing, a novel process is proposed in chapters 4 and 5. It makes use of a combination of robotic extrusion and assembly of masonry elements in insulating foam to fabricate space truss structures of improved performances.
... Having started to be employed experimental method relied on empirical data, the research process ends up with the optimisation of surface accuracy and the small curvature radii. The validation is conducted either by the finite element method (FEM) (Borg Costanzi et al., 2018;Kleespies and Crawford, 1998;Koc and Thangaswamy, 2011) or experimental method in which the laboratory experiments are conducted to test the prototypes. The accuracy and precision between digital input and physical output are tested via 3D scanners (Eigenraam, 2013;Ku and Gurjar, 2018). ...
... The integrated system proposed by Loh et al. (2019) for both adjusting double-curved surfaces by CNC fixture and trimming the inaccurate edges of the cast is an example of such systems. Hybrid system with pin mould and robotic arm are proposed by Borg Costanzi et al. (2018) and Lim et al. (2020), which is preferred for achieving a uniform surface thickness via concrete printing. 3D printing is a very promising technology also when a surface pattern is printed on fabric as an ornament (Engholt and Pigram, 2019). ...
... Then, the robotic arm defines the coordinates of the panel for trimming the edges according to the deviations of the intended panel geometry. BorgCostanzi et al. (2018) combined pin-bed with concrete 3D printing to fabricate ornamented double-curved panels.Pin movements are generally vertical. ...
Article
The rigid and one-off moulds are quite insufficient to fabricate differentiated and non-standard building components due to the low adaptation capability of mass production to changing demands of the market. Aligning with mass customisation, flexible tools are developed to solve time, cost and waste problems in moulding and casting of variable building components in the architecture, engineering, and construction. This study guides architects and engineers in the development of flexible moulds and tooling for building components. This paper aims to review the latest research trends by analysing the publications from 2004 to 2019. The systematic mapping method was adopted from software engineering to determine the-state-of-the-art technologies in flexible tools. The review study shows that flexible tools can be used to cast variable and non-standard building components by further researching on large-scale implementation, process capability and control. A survey of future trends in this promising field concludes this paper.
... This step can be critical for their design, and the previously mentioned challenges of structural continuity and watertightness remain. In the case of human handling, or machine assisted handling, of the objects, it is advisable to allow for some imprecision of the assembly step [18]. In principle, the whole handling can also be automated, but development is still needed to achieve that. ...
... Some experiments have been conducted to link concrete printing with surface support to generate shell, or shell like, geometries. The most direct of those is undoubtedly the assembled printed shell published in [18], see figure 6.3. Here the printing makes use of a CNC milled support to match the desired curvature, and generate a contour. ...
... In [18] is also mentioned the idea of doing a stress line approach with this supported printing technique, as proposed in [89]. This system could be of interest for novel structural typologies like the Trumpf foot bridge 1 visible on figure 6.4, to simplify the manufacturing. ...
Thesis
Full-text available
Il s'agit de concevoir des éléments constructifs en matériaux cimentaires en fabrication additive grande échelle. La précision géométrique et la liberté formelle apportées par le procédé d'impression 3D de pâtes de ciment à propriétés variables permet d'envisager une architecture interne de l'ordre du centimètre pour des éléments constructifs à grande échelle (typiquement de l'ordre du mètre). Pour cela il convient d'établir des cahiers des charges pertinents pour ces éléments, au regard des possibilités constructives (procédé), des propriétés atteignables (mécanique, thermique, acoustique) et de l'intérêt qu'ils peuvent présenter à un niveau architectural et industriel. La première partie du travail porte en particulier sur la conception de parois architecturées, réalisant des performances accrues
... Hence, the concrete has to support itself as it cures [85]. Because the material is extruded in a wet state, the build-up of layers must be in a manner such that they are self-supporting in order to avoid collapse, imposing somewhat of a restriction on possibilities for realizing some geometries [86]. ...
... The required concrete might cost more than traditional concrete and this would add additional costs. The lack of buildability arises because material is extruded in a wet state, and hence, the build-up of layers must be such that they are self-supporting in order to avoid collapse [86]. Any unexpected delay between depositions of successive layers could lead to formation of structurally undesirable cold joints [13]. ...
Article
This paper provides a critical review of the related literature on 3D printing in construction. The paper discusses and evaluates the different 3D printing techniques in construction. The paper also discusses and categorizes the benefits, challenges, and risks of 3D printing in construction. The use of 3D printing technology offers several advantages over traditional methods. However, it comes with its own additional challenges and risks. The main benefits of 3D printing in construction include constructability and sustainability benefits. The challenges are categorized into seven groups. The main challenges, found through the literature, are material related. The most cited challenges are material printability, buildability, and open time. Additionally, scalability, structural integrity, and lack of codes and regulations are frequently cited as major challenges. The additional risks are categorized into seven groups: 3D printing material, 3D printing equipment, construction site, and environment, management, stakeholders, regulatory and economic, and cybersecurity risks. The paper fills a gap in the literature as it addresses a new aspect of 3D printing, which is risk. The paper also provides some insights, recommendations, and future research ideas.
... Therefore, efforts have been made to modify traditional ME processes to offer the flexibility and ability to construct complex structures. C. Borg et al. [52] successfully 3D-printed a complex freeform interlocking structure using a four degree-offreedom extruder, with an acceptable surface finish, lower fabrication time, and less waste material (Fig. 2 (e)). B. Felbrich et al. [53] presented a 6-axis extrusion-based process inspired by the shell formation of snails to fabricate freeform architectural models, by extruding thermoplastic shells through a flat nozzle as molds, and subsequently filling them with concrete mixtures to obtain double-curved structures. ...
... [42], (c) Multi-functional concrete wall by Gosselin [47]. Freeform construction applications (d) Doubly curved specimen extruded using 6-axis extruder [53], (e) Complex geometrical shell structure with interlocking mechanism, 3D-printed at TU Delft [52]. A. Al Rashid, et al. ...
Article
Full-text available
... Intensive exploration of applications of 3D printing in the building and construction industries are driven by the potential various benefits, such as low cost, high efficiency, design flexibility, low labour expense, and highly reduced wastes [1][2][3][4][5]. It spares support of formworks in the conventional construction, which takes up 35%-60% of the total expense concrete structures [6][7][8]. Significant improvements have been witnessed in developing and adapting various 3D printing techniques to address the inadequacies of the construction-scale 3D printing. To ensure the structural stability and integrity of the printed models, the feeding cementitious materials should keep up specific properties, such as smooth flowability, continuous extrudability, sufficient buildability, and preferable mechanical stiffness [9][10][11][12]. ...
... If the time duration of one deposited layer is defined as t m , and the time gap between two adjacent layers is set as t n , then the time t for paste deposited in the i th layer can be calculated by Eq. (5). For the first layer, this time equals to t m , the relationship of P r and t can be therefore described as in Eq. (6). The mechanical bearing capacity can be predicted once the paste age or the printing mode is determined. ...
Article
h i g h l i g h t s Instant correlation between super-early age stiffness of 3D printable composite and EMI signatures was established. An optimization method for printing process based on EMI detection is proposed. PZT transducers were implemented to monitor the damage evolution of printed samples exposed to orthogonal loadings. a b s t r a c t This study is a pilot exploration to develop rigorous, green, intellectualized approach for optimal controlling the 3D concrete printing. The mechanical performances of 3D printed samples during super-early age, early age, and hardened state are tested and monitored using piezoelectric zirconate titanate (PZT) patches. EMI sensing technique is applied to quantify stiffness gain of printed concrete to evaluate the structural build-up behaviour by establishing the instant correlation between the stiffness of concrete and the EMI signatures. An optimization method for printing process based on EMI detection is proposed. In this way, the PZT signals can be feedback to the digital control system of printer in real time to adjust the printing setting. Instant intellectualization for the 3D printing technique is then realized and the buildability of the printed concrete is expected to be improved. The different early age properties of both printed and casted composites are elaborated. Thereafter, changes of frequency and amplitude in the con-ductance spectrum acquired by mounted PZT patches are employed to characterize and quantify the mechanical behaviours of the 3D printed samples exposed to orthogonal loadings, which contribute to the understanding of damage accumulation and failure process of concrete materials.
... In the study by Constanzi et al. [47], only the outer edges of the elements were 3D printed, which significantly reduced printing time. After printing, the inner portions of the elements were filled with fresh concrete. ...
... In this article, the authors propose an alternative approach for the automated production of shell-structural modules without formwork using 3D concrete printing technology. Similar to the work by Constanzi et al. [47], the module is divided into an edge zone and an inner zone to increase the rate of production. However, in the proposed technology, special attention is paid to the high ductility of edges and to the reinforcement of the modules. ...
Article
Despite all their advantages, load-bearing concrete shell structures with double curvatures are not frequently in use. The main reason is the complexity of their construction. In such a context, this article starts with a brief, critical review of existing technologies while their pros and cons are highlighted. Against that background, the authors propose a new approach for the highly automated fabrication of gridshell structures from variable modules reinforced with textile meshes. To demonstrate the feasibility of such a new technology, a demonstrator called ConDIT 1.0, a sphere-like shell structure composed of several frames, was designed and built. The frame modules were fabricated automatically using extrusion-based 3D printing and a printable, strain-hardening cement-based composite (SHCC). This article presents the design of ConDIT 1.0, the mechanical material characterization of printed SHCC, the technology of module production, the results of geometry verification for print modules using 3D scanning, and the procedure for the demonstrator’s assembly.
... 3D concrete printing is a thrusting template/formwork-free construction method that uses a computer to control the transportation and distribution of cementitious materials to realize the manufacturing of a layer-upon-layer digital model [1][2][3]. Compared with conventional concrete construction methods, 3D printing concrete can greatly reduce energy consumption and pollution in the construction process, as well as improve material efficiency [4][5][6][7]. 3D printing concrete is essential to promote greening and industrialization of the construction industry. However, the layered stacking process of 3D-printed concrete inevitably results in a weak interlayer interface, which leads to uncoordinated deformation, discontinuous mechanical properties, and weakens the overall load bearing capacities of the fabrications [8,9]. ...
... x ¼ n cur n tot (6) where n cur and n tot express the respective number of carbon atoms in the reaction between the reacted epoxy group and the total epoxy group, respectively. As shown in Table 5, the mechanical properties of the cured epoxy resin molecular model are in good agreement with the reported values. ...
... The printing head moves in 3D space over a programmed path, building up the designed structure layer by layer [2]. Various types of 3D printers are in use, including Cartesian robots [7][8][9], robotic manipulators [10][11][12] and Delta robots [13,14]. Several objects have already been produced with this technology, both for the purposes of demonstration as well as for practical uses [15][16][17][18][19]. ...
... The step motor (4) rotates the body (5), the position of which is determined by a limit switch (6). The gripper body (7) accommodates DC motors (8), which operate the gripper jaws (9). Presence sensor (10) are attached to the gripper jaws. ...
Article
Full-text available
Developments in the automation of construction processes, observable in recent years, is focused on speeding up the construction of buildings and structures. Additive manufacturing using concrete mixes are among the most promising technologies in this respect. 3D concrete printing allows the building up of structure by extruding a mix layer by layer. However, the mix initially has low capacity to transfer loads, which can be particularly troublesome in cases of external components that need to be placed on top such as precast lintels or floor beams. This article describes the application of additive manufacturing technology in the fabrication of a building wall model, in which the door opening was finished with automatic lintel installation. The research adjusts the wall design and printing process, accounting for the rheological and mechanical properties of the fresh concrete, as well as design requirements of Eurocode. The article demonstrates that the process can be planned precisely and how the growth of stress in fresh concrete can be simulated, against the strength level developed. The conclusions drawn from this research will be of use in designing larger civil structures. Furthermore, the adverse effects of concrete shrinkage on structures is also presented, together with appropriate methods of control.
... Additive manufacturing technologies are also rapidly being introduced in the construction industry as of late, mainly to reduce construction time and waste [18], whilst augmenting architectural freedom in design [19,20]. The popular method-of-choice is currently extrusionbased printing [21][22][23][24][25][26][27][28][29][30], which is similar to FDM in the sense that layers are added onto each other except that no heat is required to facilitate pumping and placement of concrete. Novel developments in concrete printing methods include shotcrete 3D printing [31][32][33][34], which essentially entails spraying concrete in layers instead of extruding filaments, injection 3D concrete printing [35] and particle-bed printing [36,37]. ...
Article
Lack-of-fusion (LOF) in digital concrete fabrication is one of the paramount technical issues that must be elucidated before mass industry implementation of this emerging technology. This review paper initially accentuates the ramifications of poor interlayer bonding, which include impaired mechanical and thermo-mechanical performance in the hardened concrete state, durability issues pertaining to corrosion of reinforcing steel and the complexities associated with numerical modeling of 3D printed structures. Focus is then placed on the mechanisms that induce LOF, which constitute an intricate combination of mechanical interaction, chemical bonding and intermolecular forces between filaments. Comprehension of these mechanisms is required to develop appropriate solutions to this problem. The paper presents current interlayer bond strength (IBS) characterization tests and their associated (dis)advantages. Lastly, solutions employed in literature to reduce LOF are presented to give readers a holistic perspective of the current state-of-the-art surrounding LOF in 3D concrete printing.
... In the fields of architecture and construction engineering, 3DCP is a catalyst and provides; the opportunity for design innovation and the use of novel concrete materials, such as local ore tailings and wastes [2][3][4][5][6][7]. Many large-scale structures have been printed and assembled; these applications have demon-strated the feasibility and immense potential of 3D printing (3DP) in real-world construction applications [8][9][10][11]. However, even though various engineering structures have been additively manufactured, 3DCP processes remain challenged by their lack of reinforcement [12][13][14][15]. ...
... In the fields of architecture and construction engineering, 3DCP is a catalyst and provides; the opportunity for design innovation and the use of novel concrete materials, such as local ore tailings and wastes [2][3][4][5][6][7]. Many large-scale structures have been printed and assembled; these applications have demon-strated the feasibility and immense potential of 3D printing (3DP) in real-world construction applications [8][9][10][11]. However, even though various engineering structures have been additively manufactured, 3DCP processes remain challenged by their lack of reinforcement [12][13][14][15]. ...
Article
3D concrete printing (3DCP) is used to manufacture freeform components by digitally controlling the distribution of concrete materials without requiring additional formwork. Recurring issues associated with 3DCP are low tensile strength and poor ductility of the nonreinforced structures. In this paper, a reconciliation printing methodology is presented for manufacturing reinforced geopolymer structures by simultaneously embedding micro-cables during the printing process. Structural arched beam and spiderweb-like structures were 3D printed and used to verify the feasibility of the proposed reinforcing method by evaluating their shape-based structural performance. A self-developed loading device was used to simulate the natural tension-only stress condition of a real spiderweb. The loading capacity of the cable-reinforced web structure was calculated and compared to the test results, which verified the bonding and the reconciliation between the micro-cable and the geopolymer matrix. As compared to the nonreinforced structures, the failure mode of the reinforced structures changed from brittle to ductile with multiple cracks, and the micro-cable reinforcement altered the strain evolution patterns. This study demonstrates that the strength of the reinforced structure was substantially increased. Further, both the method of reinforcement and the specific configuration of the 3D printed structures play a crucial role in resisting deformation and damage.
... In the fields of architecture and construction engineering, 3DCP is a catalyst and provides; the opportunity for design innovation and the use of novel concrete materials, such as local ore tailings and wastes [2][3][4][5][6][7]. Many large-scale structures have been printed and assembled; these applications have demon-strated the feasibility and immense potential of 3D printing (3DP) in real-world construction applications [8][9][10][11]. However, even though various engineering structures have been additively manufactured, 3DCP processes remain challenged by their lack of reinforcement [12][13][14][15]. ...
Article
Geopolymer has been applied to accommodate the rapid development of 3D printing in civil engineering practices and contributed this technique to reach its maximum eco-friendly potentials by eliminating the use of Portland cement. However, inherent problems with 3D printing concrete lie in the low tensile strength and poor ductility due to non-reinforcement, which greatly limit the application of 3D printing materials and structures. Hence, this study experimentally explores the feasibility of directly entraining a continuous micro steel cable (1.2 mm) during filaments (12 mm) deposition process, forming a reinforced geopolymer composite material. Three different printing path configurations are deigned to verify the applicability of micro-cable reinforced geopolymer composite for extrusion-based 3D printing. Flexural bending capacities of the proposed composite is measured and evaluated through four-point bending test. The results prove the well bonding and coordination of the micro-cable and geopolymer. Significant improvement of mechanical strength, toughness and post-cracking deformation of geopolymer composite are demonstrated.
... Although these strategies can to some extent address the limitations of 3D printed concrete structures, sufficient reinforcement of 3D printed complex geometry (e.g. doubly curved) concrete structures remains a challenge [5]. ...
Chapter
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.
... In this case, the D-shape method was applied using local materials, because of the specificity of the printing area and the gradient, resulting in economical and faster completion of the construction tasks [8]. Also, at laboratory level, examples can be found where concrete 3DP is applied on curved surfaces, that are used as supporting systems until printing parts are hardened and assembled together, comprising the overall concrete shell structure [9]. The examples so far show that a number of obstacles need to be overcome, including restrictions related to the range of free-form shapes that can be developed and limitations regarding the overhang angles that can be printed [10]. ...
Article
Full-text available
The last few decades, the application of 3D Printing (3DP) techniques in construction scale has shown an increased trend, with advantages as well as limitations, mainly related to overhanging angle restrictions during printing of complex geometries including free-form shell structures. This work suggests a five steps methodology as an alternative approach for their design and then their 3DP. In particular, in the first stage, parametric design based on the catenary concept is used for the overall geometrical configuration of free-form shells, aiming at minimization of exercised tension and compression forces. Then, Topology Optimization (TO) principles are applied, in order to reduce total material volume and at the same time to achieve structural stability of the selected shell system. This is followed by an approach for alternating individual unit members based on the functionally graded cellular structures concept, which aims at material distribution and customization in different areas. In the fourth stage, a reconfigurable formwork system is developed and used as a supporting structure for on-site 3DP in different angles and for different design configurations. Finally, the 3DP process of toolpath development and simulation are demonstrated, accompanied by real scale physical experimentation. The work is assessed in providing initial information regarding the effectiveness of the process to be used in the construction of shell structures through multi-axis 3DP assisted by reconfigurable supporting systems.
... In 3D printing application, Costanzi et al. [10] discussed the possibility of adopting a flexible mould developed at TU Delft for 3D printing applications. In the paper, they highlighted a possible work flow of using a flexible mould alongside 3D concrete printing. ...
Article
In this paper, we study the printing of non-developable curved panels using existing 3D concrete printing technology combined with a novel Adaptable Membrane Formwork. The Adaptable Membrane Formwork consists of a grid of threaded rods, whose heights are adjustable and covered by a membrane sheet. Using this method, we were able to 3D-print, for the first time, Saddle and Dome-shaped concrete surfaces, which are non-developable. The printed specimens had good print quality and geometric fidelity, as shown by quantitative assessment. The proposed method thus demonstrates great potential for the 3D printing of freeform, curved and architectural facades.
... Owing to the simplicity in directly creating specific shapes of concrete elements without the need for underlying formwork, the 3DCP can improve the total fabrication time and the labour cost in the construction industry. As a result, a rapid development in 3DCP was seen, and many studies (Khoshnevis and Dutton 1998;Bos et al. 2016;Buswell et al. 2007;Tay et al. 2017;Gosselin et al. 2016;Cesaretti et al. 2014;Khoshnevis et al. 2006;Kreiger, Kreiger, and Case 2019;Costanzi et al. 2018;Zhang et al. 2018) have shown full-scale printing with 3DCP solutions. The increase in the automation level of the approach and the decrease in the labour cost has been documented (Kreiger, Kreiger, and Case 2019;Roussel 2018). ...
Article
3D Concrete Printing (3DCP) has been gaining popularity in the past few years. Due to the nature of line-by-line printing and the slump of the material deposition in each extruded line, 3D printed structures exhibit obvious lines or marks at the layer interface, which affects surface finish quality and potentially affect bonding strength between layers. This makes it necessary to control the extrudate formation in 3DCP. However, it is difficult to directly analyse the extrudate formation process because the extrudate shape depends on many parameters. In this paper, a machine learning technique is applied to correlate the formation of the extrudate to the printing parameters using an Artificial Neural Network model. The training data for the model development was obtained from extrudates printed in 3DCP experiments. The performance of the trained model was experimentally validated and the predicted extrudate geometry resulting from the developed model showed good agreement to the actual extrudate geometry. Subsequently, the developed model was used to find proper nozzle shapes to produce designated extrudate geometries. Significant improvement on the printing quality was demonstrated using nozzle shapes generated from the model on 3D printed objects consisting a vertical wall, an inclined wall and a curved part.
... Liew et al. [122] showed this is possible for shallow concrete floors (although in that particular study not printed). Borg Costanzi et al. [123] presented a compression loaded dome structure from concrete elements printed on a double curved print bed. Recently, a bridge was unveiled in China [124] that seems to be based at least partially on compression-arch action. ...
Article
Digital fabrication techniques with concrete and cementitious materials have seen a large amount of research and industrial activity recently, with industrialization of techniques such as 3D printing becoming more of a reality. The potential to revolutionize construction is real, not only through reducing costs, but also bringing more sustainability and increased functionality. Material challenges are significant, chief among them understanding and controlling early age hydration and the link to rheology, incorporation of reinforcement, and overall, the link between processing, material, and performance, both from a structural and durability point of view. Interdisciplinarity is crucial, as the field brings together many disparate fields and has been driven by fields such as architecture so far. This article is a review of the state of the art in the newly forming field of digital fabrication with concrete, and aims to provide some direction in terms of the research challenges encountered thus far.
... Another construction method is to apply an inflatable membrane as a building formwork, to spray it with a cellulose-water mixture, and to let it freeze layer by layer to form an ice shell. Ice shell structures belong to the category of thin shell structures [14]. Theoretical analyses and the engineering practice have proved that the structural behaviour [15] of a thin shell structure is much better than that of a masonry structure. ...
... Compression-only structures using ductile composites: The geometric flexibility possible with concrete 3D printing allows manufacturing compression-only structures such as domes and arches [36,131,132]. Fig. 3 portrays a 3D printed Nubian vault. It has a funicular geometry with respect to the load due to self-weight so that the structure is fully in compression with no tensile stresses. ...
Article
This paper provides a comprehensive review of the material behaviour for extrusion-based concrete 3D printing spanning from the early age to long-term performance. We begin with a discussion on the recent progress on the understanding of early-age behaviour. Following this, the mechanical response in the hardened state, and the different strategies to introduce reinforcement are reviewed. Finally, we present insights and perspectives on the transport mechanisms in printed concrete to assess the long-term performance, and also discuss the overall impact of construction by concrete 3D printing on sustainability.
... From these intersecting points, the trajectory points in which the nozzle has to pass through during the printing will also be identified, resulting in the generated printing path. The slicing algorithm to generate printing paths for 3DCP has been discussed in several previous studies [22,23]. ...
Article
The 3D Concrete Printing technology (3DCP) has developed fast in the past few years. Compared to conventional construction method, the 3DCP technology offers an advantage in speed and cost. However, the surface of a structure from 3DCP technology requires post-finishing processes as the direct outcome suffers from low quality surface finish problem, such as jagged surface and staircase effect. This study aims to improve the surface finish quality in 3DCP using a developed novel variable-geometry nozzle that can directly control the extrudate geometry during the printing process at every layer. The nozzle assembly features an adjustable nozzle outlet geometry that can be controlled along the process. The mechanism requires a slicing algorithm to determine the extrudate geometry at every layer based on the designated printed structure. The corresponding algorithm was also developed and will be presented in this paper. Subsequently, the functionality of the proposed method was validated with a case study of manufacturing a structure with curved outer-surface geometry (an arch).
... With the development of the 3D printing concrete technique, it shows a broad application prospect in the construction field. Moreover, a large number of studies on the 3DPC has been reported [15][16][17][18][19], especially the hardened properties of largescale 3DPC components. ...
... The maturity of AM technologies in recent decades opens opportunities to advance the progress of automation in the manufacturing industry. In construction, research efforts have been directed primarily towards investigating how AM can be applied to specific construction tasks in the following areas: (1) algorithms and simulation development to assist AM implementations [71][72][73]; (2) design improvement of construction structures to enable AM implementations [74][75][76]; (3) innovative materials used for AM implementations to achieve higher printability [77]; (4) hardware to accommodate AM implementation in construction [78]; and (5) economics and scalability of AM implementation in construction [31,79,80]. Another motivation for AM applications is to achieve safety in harsh construction environments and to shrink the construction supply chain [2]. ...
Article
Full-text available
Additive manufacturing (AM) is one of the pillars of Industry 4.0 to attain a circular economy. The process involves a layer-by-layer deposition of material from a computer-aided-design (CAD) model to form complex shapes. Fast prototyping and waste minimization are the main benefits of employing such a technique. AM technology is presently revolutionizing various industries such as electronics, biomedical, defense, and aerospace. Such technology can be complemented with standardized frameworks to attract industrial acceptance, such as in the construction industry. Off-site construction has the potential to improve construction efficiency by adopting AM. In this paper, the types of additive manufacturing processes were reviewed, with emphasis on applications in off-site construction. This information was complemented with a discussion on the types and mechanical properties of materials that can be produced using AM techniques, particularly metallic components. Strategies to assess cost and material considerations such as Production line Breakdown Structure (PBS) and Value Stream Mapping are highlighted. In addition, a comprehensive approach that evaluates the entire life cycle of the component was suggested when comparing AM techniques and conventional manufacturing options.
... The literature summarised in Table 1 highlights two of the most common applications for 3DCP, the production of walls printed vertically (large length, small width, large height) and panels printed horizontally (large length, large width, small height). Both these applications drive the process to print in two modes: 1) homogeneous 'as good as cast' mode, often required for panel production [39][40][41][42]; and 'vertical shell' mode commonly used for the production of walls and columns, but also applied for printing formwork and for the production of many volumetric objects such as street furniture [6,9,43,46,47]. The shape of these may include straight or curved edges and vertices. ...
Article
Full-text available
The need for quality control and assurance in 3D Concrete Printing (3DCP) is widely recognised. Achieving geometric accuracy to a specified tolerance is a cornerstone of component-based production and assembly. Although published work within the field recognises such issues, these fall short of proposing systematic methods to evaluate, diagnose, improve, monitor and compare system performance. This work takes inspiration from the test geometry approach readily deployed in Additive Manufacturing and develops a full-scale test part to establish a reproducible benchmark for evaluating and assuring part geometric quality of 3DCP systems. The approach is used to evaluate the benefits of a new fabrication approach that combines subtractive milling on green cement mortar in combination with 3DCP. It was demonstrated to yield useful information for direct comparison of different processes and diagnosing problems for performance improvement. The test part and measurement approach offer the 3DCP community a means of cross-platform benchmarking of 3DCP system performance.
... Nematollahi et al. in [43] report some remarkable benefits of using extrusion-based additive manufacturing methods in respect of reducing the construction cost and time, reducing the injury rates and increasing architectural freedom. Several types of construction 3D printers such as Cartesian robots [44], robotic arms (manipulators) [45], cable driven parallel robots [46] and Delta robots [47] are currently in used and various objects [41] have been produced by these robotic platforms. In a concrete 3D printing process, printing speed, printhead shut-off system, stand-off distance (SOD) and temperature are parameters which are needed to be controlled and predefined as they affect the shape, quality and behavior of printed concrete objects [48; 49] ...
Thesis
Construction 3D printing is a form of additive manufacturing which represents a process of fabricating buildings or construction components from a digital file by depositing a building material layer by layer without any formwork support. In this research work, an application of the automated planning, which is an artificial intelligence (AI) technique, to construction 3D printers is presented. On this basis, AI planners, expressed in Planning Domain Definition Language (PDDL 2.1), are developed and employed to generate a sequence of operations comprehensible to the control system of a robotic manipulator system which is to perform specific concrete 3D printing tasks to produce two spatial objects with different geometry specifications. Accordingly, AI planners are executed based on requirements of printability checking and prefabrication in robotic construction 3D printers. The planned sequences will then be input to a robotic simulator framework that will allow the user to monitor the whole 3D printing process. Moreover, the performance of the approach has been examined and analyzed through scalability tests and the obtained results demonstrated that incrementing edges and layers of an object causes an increase in the planner runtime. The work described in this paper addresses a new application of AI concepts to the robotic additive manufacturing domain so far lacking in the scientific literature.
... In the study by Borg Constanzi et al. [51], only the outer edges of the elements were 3D printed, which significantly reduced printing time. After printing, the inner portions of the elements were filled with fresh concrete. ...
Preprint
Full-text available
Despite all their advantages, load-bearing concrete shell structures with double curvatures are not frequently in use. The main reason is the complexity of their construction. In such a context, this article starts with a brief, critical review of existing technologies while their pros and cons are highlighted. Against that background the authors then propose a new approach for the highly automated fabrication of gridshell structures from variable modules. To demonstrate the feasibility of such a new technology, a demonstrator called ConDIT 1.0, a sphere-like shell structure composed of several frames was designed and built. The frame modules were fabricated automatically using extrusion-based 3D printing and a printable, strain-hardening cement-based composite (SHCC). This article presents the design of ConDIT 1.0, the mechanical material characterization of printed SHCC, the technology of module production, the results of geometry verification for print modules using 3D scanning, and the procedure for the demonstrator’s assembly. TRANSLATE with x English ArabicHebrewPolish BulgarianHindiPortuguese CatalanHmong DawRomanian Chinese SimplifiedHungarianRussian Chinese TraditionalIndonesianSlovak CzechItalianSlovenian DanishJapaneseSpanish DutchKlingonSwedish EnglishKoreanThai EstonianLatvianTurkish FinnishLithuanianUkrainian FrenchMalayUrdu GermanMalteseVietnamese GreekNorwegianWelsh Haitian CreolePersian TRANSLATE with COPY THE URL BELOW Back EMBED THE SNIPPET BELOW IN YOUR SITE Enable collaborative features and customize widget: Bing Webmaster Portal Back
... In the case of fabric molds, the CNC fabrication process can be used to construct double-curve concrete. However, it consumes great costs and time, and is suitable for cases where more than one identical unit is needed [33]. CNC milling molds based on ice are used to produce concrete. ...
Article
Full-text available
With the development of technology, the number of free-form structures—as well as their value—is increasing. In order to construct such free-form structures, a number of studies are being conducted on free-form molds from multifaceted perspectives. However, it is difficult to identify the progress of studies related to free-form molds, as the scope of the studies is redundant or similar in many cases. Therefore, the current study focused on the identification of the trends of preceding studies on free-form molds using the PRISMA technique. The study classified the studies into three topics in order to identify the trends: ‘free-form curve fabrication technology’, ‘free-form mold fabrication technology’, and the ‘analysis of free-form panel forms.’ Each topic was further categorized into two tiers for more in-depth analysis. The whole process was adopted in order to suggest the trends of studies on free-form molds. The findings are expected to be used to provide fundamental data for future studies on free-form molds, and to set the directions for new studies.
... With the development of the 3D printing concrete technique, it shows a broad application prospect in the construction field. Moreover, a large number of studies on the 3DPC has been reported [15][16][17][18][19], especially the hardened properties of largescale 3DPC components. ...
Article
This study systematically investigates the hardened properties, durability and void distribution of large-scale 3D printed cement-based materials (3DPC). Experimental results indicate that 3DPC has higher compressive and flexural strengths, lower drying shrinkage, better resistance against sulfate attack and carbonation than mold-cast cement-based materials, but lower resistance to frost damage and chloride ion penetration. Computed tomography scanning reveals that voids in 3DPC are strongly oriented along the printing direction. Furthermore, the voids are much more inter-connected and even continuous among the printed filaments. This unique void distribution is the origin of anisotropy for 3DPC and can explain the determined directional dependency of mechanical strengths and durability performance. Along the printing direction, the more connected voids render more channels for gas and liquid to penetrate into 3DPC.
... Nematollahi et al. in [12] report some remarkable benefits of using extrusion-based additive manufacturing methods in respect of reducing the construction cost and time, 20 reducing the injury rates and increasing architectural freedom. Several types of construction 3D printers such as Cartesian robots [13], robotic arms (manipulators) [14], cable driven parallel robots [15] and Delta robots [16] are currently in use and various objects [10] have been produced by these robotic platforms. ...
Article
Full-text available
In this paper, to have control over geometry specifications of rectangular bar-shaped layers in a robotic concrete 3D printing process, a real-time vision-based control framework is developed and proposed. The proposed control system is able to set the layer-width by automatically adjusting the velocity of an industrial manipulator during the 3D printing process of concrete based materials relying on a vision system feedback. Initially, details related to the control system, vision and processing units, and robotic platform are discussed. In continue, technical descriptions related to the printhead design, conversion process from a digital 3D drawing model to numerical motion control commands of an industrial manipulator and building material used in this work are reported. The reliability and responsiveness of the developed system is then evaluated through experimental tests by printing several single bar-shaped layers with different wideness by means of an unique printhead geometry and also by printing two layers with the same dimension centrally above another. Overall, the high accuracy and responsiveness of the developed system demonstrate a great potential for real-time vision-based control of industrial manipulators for layer-width setting in concrete 3D printing applications.
... Concrete 3D printing's geometric flexibility enables the fabrication of compression-only structures such as domes and arches [204,205]. It has a funicular geometry in relation to the load imposed by self-weight, resulting in a structure that is completely compressed and free of tensile stresses [206]. ...
Article
The construction sector has embraced digitalization and industrialization to boost production, reduce material consumption, and improve workmanship. The 3D-printed concrete technology (3DPCT), more broadly recognized as the design of a 3D object via a computer-aided design (CAD) model or a digital 3D model, has accelerated considerable progress in these areas in other industries. Although 3DPCT has advanced remarkably in recent years, producing an appropriate 3D printing material that improves performance while reducing material consumption, which is really important for CO 2 reduction, is urgently needed. The present 3DPCT faces many obstacles, one of which is the limited range of printable concretes. To tackle this limitation, extensive studies on developing creative approaches for formulating alkali-activated materials (AAMs) for 3DPCT for modern building applications have been conducted. AAMs are maintainable substitutive binders to ordinary Portland cement. Therefore, the need to undertake a comprehensive literature review on the current status of AAM performance on 3D-printable concretes for building applications is substantial. This article comprehensively reviews the quality requirements, advantages, disadvantages, common techniques, delivery, and placement of 3DCP. This literature also delivers indepth reviews on the behaviors and the properties of AAM-based concrete composites used in 3D-printed construction. Moreover, research trends are moving toward a wide-ranging understanding concerning the economic benefits and the environmental footprints of 3DCP for building applications with AAMs as suitable concrete materials for the emerging robust eco-friendly concrete composite for digital construction constructions nowadays. Given the merits of the study, several hotspot research topics for future investigations are also provided for facilitating the wide use of 3DPCT in real applications to address rapidly the gap between demand and supply for smart and cost-effective homes for upcoming generations.
... Although the process offered adequate accuracy, it resulted in a relatively long printing time [7]. Borg Costanzi et al. [16] were printing only the outer layer of the module and then filling the infill with fresh concrete, which significantly reduced the production time. The last group of approaches was done fully automated, however, the methods of reinforcing the modules have not been demonstrated. ...
Article
Although they are very efficient structures, concrete shells have lost popularity due to the complexity of the traditional construction process using cast-in-place concrete. A key concept to overcome the labor-intensive formwork in situ is the segmentation of the shells into prefabricated parts. In order to avoid individual formworks during prefabrication as well, the authors rely on extrusion-based 3D printing of strain-hardening cement-based composite (SHCC). The goal is a highly automated, scalable, and adaptable flow-prefabrication of modules controlled by a holistic digital design process. Such the creation of modular free-form shell structures can be accelerated significantly, resulting in structures comparable with gridshells. Starting with the problem statement and the elaboration of the technology used, the main contribution of this research is the development of geometrical methods for modularization based on given production conditions. The challenge lies in the free-form geometry discretization with respect to the structural analysis and within the defined constraints such as planar quads, no edge torsion, and minimal material consumption. Methods of discrete differential geometry for circular PQ (planar quad) mesh generation are combined with Response Surface Methodology (RSM) for multi-objective optimization of the global parameterized shape. The results were illustrated in a study case where the geometrical and structural production parameters of starting and final shell are compared.
... Other researchers have sought to add adaptivity to the construction process through the use of additive manufacturing and industrial robotic arms. 9 Developments in concrete formwork 3D-printing, 10,11 and material deposition on custom, non-planar surfaces, [12][13][14] demonstrate the potential of integrating additive manufacturing and robotic arms as part of an adaptive fabrication method. However, despite the growing number of research studies carried out in this area, the additive manufacturing approach is still under development and has struggled with a variety of practical considerations, including the strength of the product and the ability to implement reinforcing components inside the 3D-printed concrete elements. ...
Article
The design and manufacturing of concrete elements need to be reconsidered in light of current trends in architectural geometry. Today, there is a movement toward greater customization and adaptability of concrete elements using “reconfigurable formworks” and “additive manufacturing.” Our study approached the issue of fabricating non-standardized concrete elements from the perspective of a “reconfigurable fabrication platform.” Specifically, we developed a method of fabricating geometrically diverse concrete joints by combining flexible pressure-enduring tubes with a rigid mechanism, resulting in an adaptive concrete-casting machine. This platform, which we named “Flexi-node,” can be used in conjunction with a relevant fabrication-aware digital design tool. Users can computationally design and fabricate a great variety of concrete joints using just one mold, with a minimum of material waste and with no distortion from hydrostatic pressure as would typically occur in a fully flexible formwork.
... Traditional formwork methods comprise wooden (solid) formwork as temporary support for flat roofs, pneumatic formwork for curved roofs [67], and backfilling with sand such as in construction with slab on grade. The viscous behavior of printed concrete challenges the fabrication of cantilever elements, which motivated innovative methods such as flexible molds for 3D printed shells [68], which act as formwork, and 3D sand-printed floors with varied rib geometries from compression-only form finding algorithms [69], which serve as integrated formwork. These solutions can be implemented in the context of concrete 3D printing but would hinder a full automated process that is envisioned in this paper. ...
Article
This paper reviews and extracts lessons from historic buildings, whose stability relies mainly on compression to resist gravity loads, that can inform the construction of affordable housing and shelters using 3D printed concrete without reinforcement and formwork. The first part consists of a literature survey of historic constructions with systems relying on compression considering four vectors of analysis: (1) form; (2) structural principle; (3) materials; and (4) construction process. The survey starts by identifying forms whose structural principle may be adequate for 3D printing of concrete applications. Then, historic structures displaying similar forms are analyzed in terms of structural behavior, the types of materials employed, and the construction process used to obtain foundations, walls, and roofs. A series of historically inspired shapes for printing is thus obtained from this survey. To address the printability of the structures identified after the survey, the second part of the paper provides a brief description of existing processes for construction scale printing considering material aspects, such as fresh state behavior, and printing system configurations. Addressing the fresh state properties of concrete is crucial as it determines whether the structure fails during printing. Finally, a set of strategies including potential toolpaths and intermediate states are defined to print the identified forms, considering issues concerning material requirements and printing process.
... 3DCP has an advantage in creating bespoke components because it eliminates the need for a mould, and thus it is cost-effective for lowvolume manufacturing. It has become a steering index of digital construction with numerous successful applications in practical engineering, such as 3D printed bridges, bus stations, public toilets, and villas, reflecting the strong development potential of 3DCP technology [6][7][8][9][10][11]. In October 2019, a 3D printed concrete bridge with a single span of 18.04 m was built on the Beichen Campus of Hebei University of Technology, Tianjin, China as shown in Fig. 1. ...
Article
3D concrete printing has tremendous potential for construction manufacturing; however, weak interface bonding between adjacent layers remains a well-known issue that affects the mechanical properties of printed structures. The layers introduce anisotropy and reduce the capacity to resist tensile and shear loads. Reinforcements, inserted perpendicular to the printed layers to traverse the interfaces, can improve these limitations, but the insertion of reinforcements is difficult to achieve in practice, and there are few published studies exploring appropriate methods. This study presents a promising approach using U-shaped nails inserted into concrete during the printing process. The bridging effect and dowel action of the applied U-nails are visualised and analysed to elucidate the toughness improvement. The ultimate tensile strength and shear strength of 3D printed concrete are significantly increased by 145.0% and 220.0%, respectively. U-nails with a filament thickness of 2–2.5 mm are recommended to yield optimal improvement in the interlayer strength.
... More fundamentally though, it should be noted that even without these additional loads, the stress state within the object during printing is unlikely to be one of uniaxial compression, as this could only be the case if the support is frictionless [25,27]. But in reality, the friction between the print surface and the print object can generally not be neglected, as can easily be established by tilting a print surface with fresh printed concrete and noticing that it will not immediately slide [28]. The support friction results in confining stresses, as illustrated in Fig. 2. For a transverse section of a print wall, it was shown by Kruger et al. [27] that bi-axial stresses occur over a significant area, particularly at the bottom. ...
Article
Full-text available
Both industry and academia are rapidly developing processes, materials, and projects to explore the potential of extrusion-layering additive manufacturing of cementitious materials, generally known as 3D concrete printing (3DCP). Because the lack of supportive formwork makes objects prone to failure during printing, a key aspect remains the so-called ‘buildability’, a qualitative descriptor to indicate the resistance against such failures. Obviously, the material characteristics of the applied print mortar are an important (although not sole) parameter to determine buildability. However, it is not yet clear which material properties are the most suitable, and how they should be determined experimentally. In literature, a range of approaches has been suggested, but comparative studies are very few in number and limited in scope. This paper presents a juxtaposition of fresh material characterisation methods by subjecting four different mortars to a range of tests related to buildability, including rotational rheometry, unconfined uniaxial compression tests, direct shear tests, and ultrasonic wave transmission tests. For reference, some hardened state properties were also determined, and a printing trial was performed on one mixture. Significant differences between the mixtures were found, even though three of the four mixtures were composed of different proportions of the same 4 dry materials, including different development characteristics. Furthermore, it was shown that strength values from different experiments could only be correlated by assuming significant friction angles associated with Mohr-Coulomb failure behaviour. We propose this could be established relatively easily through a novel method, by combining rheometry-shear and uniaxial compression test results. The data seem to indicate this would be a valid approach. Normalized but physically different parameters, such as compressive strength and pulse velocity, could not be consistently correlated. Their proportions are time and mixture-dependent, which adds significant complexity to quality control and the development of generalized methods to characterize and compare buildability of cementitious mortars.
... Although this approach has certainly been shown to add adaptivity in the fabrication process, the main drawback results from the hydrostatic pressure of the concrete, which is liable to produce deformation and distortion in the cast part. To help combat this problem, researchers have used cement paste-coating techniques, pneumatic formworks, and a variety of other methods generally resulting in shell-like or hollow components (Popescu 2016(Popescu /2018Kromoser 2016;Costanzi et al. 2018). ...
Conference Paper
Full-text available
Article
Full-text available
The proliferation of digital technologies considerably changed the field of architecture. Digital fabrication pushes architecture into an unexpected new domain of previously unachievable complexity, detail, and materiality. Understanding these technologies’ impact can help direct future research, innovate design and construction processes, and improve the education of future professionals. However, comprehensive reviews offering a holistic perspective on the effects of 3D printing technologies on architecture are limited. Therefore, this study aims to provide a systematic review of state-of-the-art research on 3D printing technologies in architectural design and construction. The review was performed using three major databases, and selected peer-reviewed journal articles published in the last ten-year period were included in quantitative and qualitative analyses. Using bibliometric analysis, the research progress is summarized through the identified trend of the annual number of articles, prominent authors and co-authorship network, and key topics in the literature organized in three clusters. Further, content analysis of selected articles enabled coding cluster themes. Moreover, the analysis differentiated two categories of 3D printing technologies based on the scale of the system, elaborating their peculiarities in terms of materials, methods, and applications. Finally, challenges and promising directions for future work and research challenges are discussed. Keywords: architecture; design; digital fabrication; construction industry; additive construction; additive manufacturing; rapid prototyping; 3D printing; models; prototypes
Article
The copper alloy shell is an important component, and its forming methods include hot forging, spinning, and multi-pass cold extrusion. The purpose of this paper is to study a new process of bimetallic 3D printing technology in the integrated manufacturing of copper alloy shells. In this paper, the 3D printing technology and bimetal 3D printing technology are briefly described first, and then the experimental analysis of 3D printing technology is carried out, and then the three-dimensional model of the copper alloy water meter is established. Through analysis and comparison, the experimental results show that with the increase of sintering temperature, the density of copper alloy samples gradually increases. Because the copper powder particles are more closely combined with the increase of the sintering temperature, the relative density of the sample becomes larger and larger. The integrated copper alloy shell through 3D printing technology remanufacturing technology can change the density, thermal conductivity, dynamic viscosity coefficient and solid phase rate of the integrated copper alloy shell under the condition of setting a certain temperature. Higher plasticity and thermal conductivity. The copper alloy shell integrated by bimetal 3D printing remanufacturing technology can improve the application range of alloy materials.
Book
Full-text available
Libro de Resúmenes correspondiente a las ponencias del Congreso Internacional de Innovación Tecnológica en Edificación.
Article
Quantitative damage identification of surrounding rock is important to assess the current condition and residual strength of underground tunnels. In this work, an underground tunnel model with marble-like cementitious materials was first fabricated using the three-dimensional (3D) printing technique and then loaded to simulate its failure mode in the laboratory. Lead zirconate titanate piezoelectric (PZT) transducers were embedded in the surrounding rock around the tunnel in the process of 3D printing. A 3D monitoring network was formed to locate damage areas and evaluate damage extent during loading. Results show that as the load increased, main cracks firstly appeared above the tunnel roof and below the floor, and then they coalesced into the tunnel boundary. Finally, the tunnel model was broken into several parts. The resonant frequency and the peak of the conductance signature firstly shifted rightwards with loading due to the sealing of microcracks, and then shifted backwards after new cracks appeared. An overall increase in the root-mean-square deviation (RMSD) calculated from conductance signatures of all the PZT transducers was observed as the load (damage) increased. Damage-dependent equivalent stiffness parameters (ESPs) were calculated from the real and imaginary signatures of each PZT at different damage states. Satisfactory agreement between equivalent and experimental ESP values was achieved. Also, the relationship between the change of the ESP and the residual strength was obtained. The method paves the way for damage identification and residual strength estimation of other 3D printed structures in civil engineering.
Conference Paper
Günümüzde en çok kullanılan yapı malzemesi beton olmakla birlikte, yapıların inşasında en çok tercih edilen imalat yöntemi geleneksel bir yöntem olan kalıpla inşa yöntemidir. Ancak, kalıpla üretim yöntemi kalıp ve işçilik maliyeti, imalat süresi, tasarım özgürlüğü, ve iş sağlığı ve güvenliği gibi birçok açıdan çeşitli dezavantajlara sahip olmasından dolayı birçok özel, ticari ve akademik kurum alternatif imalat yöntemleri arayışına girmiş ve yüksek teknolojili ekipmanlar kullanılarak gerçekleştirilen 3 boyutlu eklemeli imalat (3D Additive Manufacturing – 3D AM) yöntemi bu arayışa cevap olmuştur. Gelişen teknoloji ile birlikte, 3D AM yöntemi, mevcut yapı endüstrisinin bazı zorluklarına çözüm olabilecek yaklaşımlardan bir tanesi olarak benimsenmiştir. 3D AM yöntemini kısaca katman üzerine katman eklemek suretiyle yapı imalatı olarak ifade etmek mümkündür. 3D AM ile yapıların inşası, geleneksel beton üretim yöntemlerine kıyasla çok daha fazla tasarım özgürlüğü tanıyan, daha hızlı, daha az atık üreten, daha ekonomik, işçilik hatalarını ortadan kaldıran, kalıp gerektirmeyen ve daha sürdürülebilir yöntemdir. 3D AM teknolojisi ile birlikte, beton, malzeme kaynaklı çevresel etkiler azaltılarak, son ürünün kalitesini artırmakta ve geometrik olarak daha karmaşık projelerin hızlı bir şekilde yapımına olanak sağlamaktadır. Bu nedenle 3D AM yöntemi sahip olduğu bu avantajlar sayesinde son zamanlarda inşaat sektöründe popülerlik kazanmaya başlamıştır. Bu derleme çalışmasında, 3D AM yönteminin yapı teknolojisinde geçmişten günümüze geçirdiği süreç hakkında genel bir bilgi verilerek yöntemin avantajları, geliştirilmesi gereken yönleri hakkında çeşitli bilgiler verilecektir. 3D AM yönteminin gelecekte yapı teknolojisinde yaygın olarak kullanılacağı düşünülmekte olup, bu manada makale yazarları tarafından bu kapsamda gelecekte ülkemizde yapılması gereken çalışmalar özetlenecektir.
Article
3d printing of cementitious material is a relatively new additive manufacturing process whose growing interest and fast development is mainly due to the digitalised manufacturing, allowing the disposition of material where it pleases. Yet, due to the properties of the fresh material and the difficulty to generate paths for the robots, the printed geometries have remained simple. In this regard, this papers longs to broaden the range of printable shapes by proposing a process-aware exploration of the 3d printing design space. This is done by looking at historic strategies that have been developed to build cantilevers, vaults and domes in masonry - a more ancient additive manufacturing process. Similarities and main differences between the two processes are pointed out, at the scale of the component, the layer and the global structure. From that a classification of masonry strategies to build cantilevers is proposed, facilitating the identification of parameters for 3d printing that will allow to reproduce such structures. Later, some guidelines for the design of printable geometries and the generation of robotic toolpaths are given, in the light of previous findings.
Chapter
Additive manufacturing (AM) or 3D printing is a rapid prototyping process that has captured the attention of architects and designers worldwide in the last few years. Multiple research groups and commercial entities are exploring different areas of 3D concrete printing (3DCP) with one of the main topics being the potential to improve the design freedom, while simultaneously achieving sufficient structural ductility. Based on the target design impression of a free form 3DCP structure, this study presents a number of 3DCP strategies to print arbitrary double-curved geometries with improved concrete ductility. A digital design-to-fabrication workflow was applied, consisting of defining parameters at various stages of the process. Two case study objects have been printed, both featuring double-curved surfaces achieved through cantilevered printing with support material, and by printing on a curved support surface, respectively. The former object acted as support for the latter. Entrained cables and secondarily added glass fibres were used to obtain ductility. The result is a double-curved 1 $$\times$$ 1 m panel with fibre-reinforced printed concrete, as well as a double curved print bed, reinforced with high strength steel cables.
Article
Full-text available
As a rapid prototyping technology, 3D printing technology has been successfully utilized in medical treatment, jewelry, precision parts manufacturing, aviation and other fields. Meanwhile, owing to its feature of energy saving and emission reduction, it is attached high importance to in recent years. However, due to the problems of printing equipment and materials, and evaluation standards, the research progress of building 3D printing technology is far from sufficing the practical demand of large-scale manufacture in the construction industry. This paper starts with an introduction to the classification and development history of building 3D printing technology, explains its current research and application status, and propose outlooks for the prospective development.
Article
Full-text available
3D Printing concrete is new developed technology with no reinforcement or by providing reinforcement as like cable in the year 1987. The printing concrete is printed with the printer in different shapes and sizes. Size of aggregate used is very minimum which passes through the nozzle of printer. The strength of 3DPC is tested by compression, flexural, tensile, shear tests for identifying durability, extrudability, workability of printing concrete. The slump flow is carried for finding the flowability of concrete that passes through the nozzle of the printer. Fibers such as polypropylene, PVA, GGBS, Steel were used in addition of mix to increase the strength of 3DPC. Superplasticizers, Fly ash Silica fume, Geopolymer are used in concrete with percentage addition into the mix for raising the strength of the printing concrete. Result shows the strength of PC in different mix proportions along with varring size of specimens. Pumpabality and Buildability of printing concrete is analysed by slump flow test. Reinforcement for this concrete is provided as in form of cables that passes freely through nozzle for printing the concrete.
Article
Doubly-curved ribbed concrete shells are a materially efficient means of spanning large areas such as roofs and floors. However, the fabrication of such structures poses challenges in terms of formwork manufacturing as well as material deposition. This has led to their decline compared to more prismatic shapes such as flat slabs which can be manufactured more economically. This paper presents a novel fabrication process called Automated Robotic Concrete Spraying (ARCS) by which glass fibre reinforced concrete (GFRC) is sprayed onto a curved formwork to create thin shell components of variable thickness. The trajectory planning and generation algorithm developed and implemented in ARCS to create such components is presented. Two sets of prototype shells were fabricated: one which forms the segments of a larger structural floor demonstrator and another consisting of a single component with deep ribs on a thin shell. The sequencing used to generate the spray paths for each component is outlined, with each prototype using two different strategies to add ribs onto the fabricated shells. While the fabrication process has been used in conjunction with a pin-bed mould actuating flexible formwork to create the spraying surface, the trajectory planning approach is adaptable enough such that any formwork can be utilised. Combined with the output speed of material deposition, ARCS offers the potential to enable mass production and customisation of doubly-curved ribbed structural concrete shells of variable thickness as an industrial process at an architectural scale.
Article
Full-text available
In the field of digital fabrication, additive manufacturing (AM, sometimes called 3D printing) has enabled the fabrication of increasingly complex geometries, though the potential of this technology to convey both geometry and structural performance remains unmet. Typical AM processes produce anisotropic products with strength behavior that varies according to filament orientation, thereby limiting its applications in both structural prototypes and end-use parts and products. The paper presents a new integrated software and hardware process that reconsiders the traditional AM technique of fused deposition modelling (FDM) by adding material explicitly along the three-dimensional principal stress trajectories, or stress lines, of 2.5-D structural surfaces. As curves that indicate paths of desired material continuity within a structure, stress lines encode the optimal topology of a structure for a given set of design boundary conditions. The use of a 6-axis industrial robot arm and a heated extruder, designed specifically for this research, provides an alternative to traditional layered manufacturing by allowing for oriented material deposition. The presented research opens new possibilities for structurally performative fabrication. Copyright © 2016 by Kam-Ming Mark Tam, Caitlin T. Mueller, James R. Coleman, and Nicholas W. Fine. Published by the International Association for Shell and Spatial Structures (IASS) with permission.
Article
Full-text available
In this paper, a non-conventional way of additive manufacturing, curved-layered printing, has been applied to large-scale construction process. Despite the number of research works on Curved Layered Fused Deposition Modelling (CLFDM) over the last decade, few practical applications have been reported. An alternative method adopting the CLFDM principle, that generates a curved-layered printing path, was developed using a single scripting environment called Grasshopper – a plugin of Rhinoceros®. The method was evaluated with the 3D Concrete Printing process developed at Loughborough University. The evaluation of the method including the results of simulation and printing revealed three principal benefits compared with existing flat-layered printing paths, which are particularly beneficial to large-scale AM techniques: (i) better surface quality, (ii) shorter printing time and (iii) higher surface strengths.
Article
Full-text available
Process-based biomimetics focuses on the transfer of biological principles to architectural construction. To realise the ICD/ITKE Research Pavilion 2014 -15, presented here by Moritz Doerstelmann, Jan Knippers, Valentin Koslowski, Achim Menges, Marshall Prado, Gundula Schieber and Lauren Vasey of the Institute for Computational Design (ICD) and Institute of Building Structures and Structural Design (ITKE) research team at the University of Stuttgart, sensor-driven robotic fabrication was combined with advanced design computation and simulation. This enabled the construction of an architectural fibre structure on a pneumatic mould, drawing on the complex design of the web of a water spider.
Thesis
Full-text available
The production of precast, concrete elements with complex, double-curved geometry is expensive. This is caused by the high cost of the necessary moulds and the limited possibilities for reuse. Currently, computer numerically controlled milled foam moulds are the solution applied in various projects. These moulds deliver good aesthetic performance, but also result in a waste of material, relatively low production speed and fairly high costs per element. The flexible mould method, as discussed in this thesis, offers an economic alternative for the state of art: it allows repeated reuse of the same mould in an adapted shape.
Article
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.
Article
Viscometers in general have never been particularly popular at the jobsite. They are however well suited at the laboratory as they measure concrete consistency in terms of fundamental physical quantity, known as the yield stress and plastic viscosity. In contrast to viscometers, the slump cone is by far the most accepted tool for measuring consistency at the jobsite. This is due to its simplicity in handling. With the significance of both types of devices, it is clearly important to relate them to each other. The result of this study suggests a relationship between the yield stress and slump that depends on the concrete mixture proportions. More precisely, a particular trend line between the yield stress and slump seems to depend on volume fraction of matrix used in the concrete. The study shows a low correlation between the slump and plastic viscosity.
Developing a computational approach towards a performance based design and robotic fabrication of fibrous skin structures