Construction 3D printing

Construction 3D Printing refers to various technologies that use 3D printing as a core method to fabricate buildings or construction components. The term was first coined by James B Gardiner in 2011.^[1]

There are a variety of 3D printing methods used at construction scale, these include the following main methods: extrusion (concrete/cement, wax, foam, polymers), powder bonding (polymer bond, reactive bond, sintering) and additive welding. 3D printing at a construction scale will have a wide variety of applications within the private, commercial, industrial and public sectors. Potential advantages of these technologies include faster construction, lower labor costs, increased complexity and/or accuracy, greater integration of function and less waste produced.

A number of different approaches have been demonstrated to date which include on-site and off-site fabrication of buildings and construction components, using industrial robots, gantry systems and tethered autonomous vehicles. Demonstrations of construction 3D printing technologies to date have included fabrication of housing, construction components (cladding and structural panels and columns), bridges and civil infrastructure^[2], artificial reefs, follies and sculptures.

History

Seeding technologies 1950 - 1995

Robotic bricklaying was conceptualized and explored in the 1950s and related technology development around automated construction began in the 1960s, with pumped concrete and isocyanate foams.^[3] Development of automated fabrication of entire buildings using slip forming techniques and robotic assembly of components, akin to 3D printing, were pioneered in Japan to address the dangers of building high rise buildings by Shimizu and Hitachi in the 1980s and 1990s.^[4] Many of these early approaches to on-site automation foundered because of the construction 'bubble', their inability to respond to novel architectures and the problem of feeding and preparing materials to the site in built up areas.

Early developments 1995 - 2000

Early construction 3D printing development and research have been under way since 1995. Two methods were invented, one by Joseph Pegna ^[5] which was focused on a sand/cement forming technique which utilized steam to selectively bond the material in layers or solid parts, though this technique was never demonstrated.

The second technique, Contour Crafting by Behrohk Khoshnevis, initially began as a novel ceramic extrusion and shaping method, as an alternative to the emerging polymer and metal 3D printing techniques, and was patented in 1995.^[6] Khoshnevis realized that this technique could exceed these techniques where "current methods are limited to fabrication of part dimensions that are generally less than one meter is each dimension". Around 2000, Khoshnevis's team at USC Vertibi began to focus on construction scale 3D printing of cementitious and ceramic pastes, encompassing and exploring automated integration of modular reinforcement, built-in plumbing and electrical services, within one continuous build process. This technology has only been tested at lab scale to date and controversially and allegedly formed the basis for recent efforts in China.

First generation 2000 - 2010

In 2003, Rupert Soar secured funding and formed the freeform construction group at Loughborough University, UK, to explore the potential for up-scaling existing 3D printing techniques for construction applications. Early work identified the challenge of reaching any realistic break-even for the technology at the scale of construction and highlighted that there could be ways into the application by massively increasing the value proposition of integrated design (many functions, one component). In 2005, the group secured funding to build a large-scale construction 3D printing machine using 'off the shelf' components (concrete pumping, spray concrete, gantry system) to explore how complex such components could be and realistically meet the demands for construction.

In 2005 Enrico Dini, Italy, patented the D-Shape technique, employing a massively scaled powder jetting/bonding technique over an area approximately 5m x 5m x 2.5m.^[7] This technique although originally developed with epoxy resin bonding system was later adapted to use inorganic bonding agents.^[8] This technology has been used commercially for a range of projects in construction and other sectors including for [artificial reefs].^[9]

In 2008 3D Concrete Printing began at Loughborough University, UK, headed by Richard Buswell and colleagues to extend the groups prior research and look to commercial applications moving from a gantry based technique ^[10] to an industrial robot, which they succeeded in licensing the technology to Skanska in 2014.

Second generation 2010 - present

On January 18, 2015 the company gained further press coverage with the unveiling of 2 further buildings, a mansion style villa and a 5 storey tower, using 3D printed components.^[11] Detailed photographic inspection indicates that the buildings were fabricated with both precast and 3D printed components. The buildings stand as the first complete structures of their kind fabricated using construction 3D printing technologies. In May 2016 a new 'office building' was opened in Dubai.^[12] The 250-square-metre space (2,700 square foot) is what Dubai's Museum of the Future project is calling the world's first 3D-printed office building. In 2017 an ambitious project to build a 3D printed skyscraper in the United Arab Emirates was announced.^[13] Cazza construction would help to build the structure. At present there are no specific details, such as the buildings height or exact location.^[14]

FreeFAB Wax™,^[15] invented by James B Gardiner and Steven Janssen at Laing O'Rourke (construction company). The patented technology has been in development since March 2013.^[16] The technique uses construction scale 3D printing to print high volumes of engineered wax (up to 400L/hr) to fabricate a 'fast and dirty' 3D printed mould for precast concrete, glass fibre reinforced concrete (GRC) and other sprayable/cast-able materials. The mould casting surface is then 5 axis milled removing approximately 5mm of wax to create a high quality mould (approximately 20 micron surface roughness).^[17] After the component has cured, the mould is then either crushed or melted-off and the wax filtered and re-used, significantly reducing waste compared to conventional mould technologies. The benefits of the technology are fast mould fabrication speeds, increased production efficiencies, reduced labour and virtual elimination of waste by re-use of materials for bespoke moulds compared to conventional mould technologies.^[18]

The system was originally demonstrated in 2014 using an industrial robot.^[19] The system was later adapted to integrate with a 5 axis high speed gantry to achieve the high speed and surface milling tolerances required for the system. The first industrialized system is installed at a Laing O'Rourke factory in the United Kingdom and is due to start industrial production for a prominent London project in late 2016.^[20]

MX3D Metal founded by Loris Jaarman and team has developed two 6 axis robotic 3D printing systems, the first uses a thermoplastic which is extruded, notably this system allows the fabrication of freeform non-planar beads. The second is a system that relies on additive welding (essentially spot welding on previous spot welds) the additive welding technology has been developed by various groups in the past, however the MX3D metal system is the most accomplished to date. MX3D are currently working toward the fabrication and installation of a metal bridge in Amsterdam.^[21]

BetAbram is a simple gantry based concrete extrusion 3D printer developed in Slovenia. This system is available commercially, offering 3 models (P3, P2 and P1) to consumers since 2013. The largest P1 can print objects up to 16m x 9m x 2.5m.^[22]

Total Custom concrete 3D printer developed by Rudenko^[23] is a concrete deposition technology mounted in a gantry configuration, the system has a similar output to Winsun and other concrete 3D printing technologies, however it uses a lightweight truss type gantry. The technology has been used to fabricate a backyard scale version of a castle^[24] and a hotel room in the Philippines^[25]

Design

FreeFAB Tower 2004

FreeFAB Tower 2004 - Robotic production line of monocoque shells

Architect James Bruce Gardiner^[26] pioneered architectural design for Construction 3D Printing with two projects. The first Freefab Tower 2004 and the second Villa Roccia 2009-2010. FreeFAB Tower^[27] was based on the original concept to combine a hybrid form of construction 3D printing with modular construction. This was the first architectural design for a building focused on the use of Construction 3D Printing. The focus of the project was to explore how 3D printing could provide a silver bullet to off-site construction - by providing a direct means of fabricating 3D printed monocoque modules, simplifying the construction process. The design, although highly speculative, provided a guide to the future of construction 3D printing especially its use in off-site construction. Influences can be seen in various designs used by Winsun, including articles on the Winsun's original press release^[28] and office of the future^[29] The FreeFAB Tower project also depicts the first speculative use of multi-axis robotic arms in construction 3D printing, the use of such machines within construction has grown steadily in recent years with projects by MX3D^[30] and Branch Technology ^[31]

The Villa Roccia 2009-2010^[32] took this pioneering work a step further with the a design for a Villa at Porto Rotondo, Sardinia, Italy in collaboration with D-Shape. The design for the Villa focused on the development of a site specific architectural language influenced by the rock formations on the site and along the coast of Sardinia, while also taking into account the use of a panellised prefabricated 3D printing process. The project went through two stages of development beyond the original concept design, the first focused on the design and fabrication of a column, which was focused on the use of parametrically generated geometry and the use of space filling internal structures. The second design stage was focused on detailed design/documentation of a segment of the house, this stage also focused heavily on exploring software capabilities and on the detailed design of joints and reinforcement elements which would allow the project to be assembled and withstand weather and structural loads. The second stage of prototyping was only partially completed and the project didn't proceed to full construction.

Villa Roccia 2009 - Concept design perspective

Villa Roccia 2009 - Detailed design exploded view

Francios Roche (R&Sie) developed the exhibition project and monograph 'I heard about' in 2005 ^[33] which explored the use of a highly speculative self propelling snake like autonomous 3D printing apparatus and generative design system to create high rise residential towers. The project although impossible to put into practice with current or contemporary technology demonstrated a deep exploration of the future of design and construction. The exhibition showcased large scale CNC milling of foam and rendering to create the freeform building envelopes envisaged.

Dutch architect Janjaap Ruijssenaars's performative architecture 3D-printed building was planned to be built by a partnership of Dutch companies.^{[34] [35]} The house was planned to be built in the end of 2014, but this deadline wasn't met. The companies have said that they are still committed to the project.^[36]

Various approaches to Construction 3D Printing are being researched. Two of these are Contour crafting^[37] and D-Shape.^[38][39] Other approaches involve direct sintering of inorganic raw materials to build composite ceramic building structures, similar to the approach used with metals in direct metal laser sintering.^[40]

Structures

3D printed buildings

The 3D Print Canal House was the first full-scale construction project of its kind to get off the ground. In just a short space of time, the Kamermaker has been further developed to increase its production speed by 300%. However, progress has not been swift enough to claim the title of 'World's First 3D Printed House'.^[41]

Dutch and Chinese demonstration projects are slowly constructing 3D-printed buildings in China,^[42] Dubai^[43] and the Netherlands.^[44] Using the effort to educate the public to the possibilities of the new plant-based building technology and to spur greater innovation in 3D printing of residential buildings.^[45][46] A small concrete house was 3D-printed in 2017.^[47]

3D printed bridges

In Spain, the first pedestrian bridge printed in 3D in the world (3DBRIDGE) was inaugurated 14th of December of 2016 in the urban park of Castilla-La Mancha in Alcobendas, Madrid^[48]. The 3DBUILD technology used was developed by ACCIONA, who was in charge of the structural design, material development and manufacturing of 3D printed elements^[49]. The bridge has a total length of 12 meters and a width of 1.75 meters and is printed in micro-reinforced concrete. Architectural design was done by Institute of Advanced Architecture of Catalonia (IAAC).

The 3D printer used to build the footbridge was manufactured by D-Shape. The 3D printed bridge reflects the complexities of nature’s forms and was developed through parametric design and computational design, which allows to optimize the distribution of materials and allows to maximize the structural performance, being able to dispose the material only where it is needed, with total freedom of forms. The 3D printed footbridge of Alcobendas represented a milestone for the construction sector at international level, as large scale 3D printing technology has been applied in this project for the first time in the field of civil engineering in a public space.

Extraterrestrial printed structures

The printing of buildings has been proposed as a particularly useful technology for constructing off-Earth habitats, such as habitats on the Moon or Mars. As of 2013, the European Space Agency was working with London-based Foster + Partners to examine the potential of printing lunar bases using regular 3D printing technology.^[50] The architectural firm proposed a building-construction 3D-printer technology in January 2013 that would use lunar regolith raw materials to produce lunar building structures while using enclosed inflatable habitats for housing the human occupants inside the hardshell printed lunar structures. Overall, these habitats would require only ten percent of the structure mass to be transported from Earth, while using local lunar materials for the other 90 percent of the structure mass.^[51]

The dome-shaped structures would be a weight-bearing catenary form, with structural support provided by a closed-cell structure, reminiscent of bird bones.^[52] In this conception, "printed" lunar soil will provide both "radiation and temperature insulation" for the Lunar occupants.^[51] The building technology mixes lunar material with magnesium oxide which will turn the "moonstuff into a pulp that can be sprayed to form the block" when a binding salt is applied that "converts [this] material into a stone-like solid."^[51] A type of sulfur concrete is also envisioned.^[52]

Tests of 3D printing of an architectural structure with simulated lunar material have been completed, using a large vacuum chamber in a terrestrial lab.^[53] The technique involves injecting the binding liquid under the surface of the regolith with a 3D printer nozzle, which in tests trapped 2 millimetres (0.079 in)-scale droplets under the surface via capillary forces.^[52] The printer used was the D-Shape.

A variety of lunar infrastructure elements have been conceived for 3D structural printing, including landing pads, blast protection walls, roads, hangars and fuel storage.^[52] In early 2014, NASA funded a small study at the University of Southern California to further develop the Contour Crafting 3D printing technique. Potential applications of this technology include constructing lunar structures of a material that could consist of up to 90-percent lunar material with only ten percent of the material requiring transport from Earth.^[37]

NASA is also looking at a different technique that would involve the sintering of lunar dust using low-power (1500 watt) microwave energy. The lunar material would be bound by heating to 1,200 to 1,500 °C (2,190 to 2,730 °F), somewhat below the melting point, in order to fuse the nanoparticle dust into a solid block that is ceramic-like, and would not require the transport of a binder material from Earth as required by the Foster+Partners, Contour Crafting, and D-shape approaches to extraterrestrial building printing. One specific proposed plan for building a lunar base using this technique would be called SinterHab, and would utilize the JPL six-legged ATHLETE robot to autonomously or telerobotically build lunar structures.^[40]

Construction speed

Claims have been made by Behrokh Khoshnevis since 2006 for 3D printing a house in a day,^[54] with further claims to notionally complete the building in approximately 20 hours of "printer" time.^[55] By January 2013, working versions of 3D-printing building technology were printing 2 metres (6 ft 7 in) of building material per hour, with a follow-on generation of printers proposed to be capable of 3.5 metres (11 ft) per hour, sufficient to complete a building in a week.^[51]

The Chinese company WinSun has built several houses using large 3D printers using a mixture of quick drying cement and recycled raw materials.^[56] Ten demonstration houses were said by Winsun to have been built in 24 hours, each costing US$5000 (structure not including, footings, services, doors/windows and fitout?).^[57][58] However, construction 3D printing pioneer Dr. Behrokh Khoshnevis claims this was faked and that WinSun stole his intellectual property.^[59] This claim remains dubious given that Contour Crafting does not hold patents in China, however there are significant similarities between the methods demonstrated by Contour Crafting and those put into production by Winsun.

See also

• Building construction
• Space habitat
• Made in Space^[60]

References

External links

• Contour Crafting Project from USC, 2004
• Future of Construction Process: 3D Concrete Printing, 2010.
• Lunar Base Using 3D Printing, video, 2013.
• 3D Printing of a lunar base using lunar soil will print buildings at 3.5 meters per hour, NextBigFuture, 2013