3D Concrete Printing and Digital Construction

 Onsite and Nearsite Production

 

There are three methods for 3D printing: stereolithography, patented in 1986: fused deposition modelling, patented in 1989: and selective laser sintering, patented in 1992. It didn’t take long before research into 3D concrete printing (3DCP) began, focused on developing the equipment needed and the performance of the materials used. Twenty years later there were over a dozen experimental prototypes built, extensively documented in the 2019 book 3D Concrete Printing Technology: Construction and building applications, which also has details on the materials science required to identify successful mixtures and admixtures. The information needed to create a 3D blueprint is generated during design, and it is a relatively small step to move from a BIM model to instructions for a 3D printer.

 

By 2022 the commercialisation of 3DCP was underway, with two types of systems available. One using a robotic arm to move the print head over a small area, intended to produce structural elements and precast components, the other a gantry system for printing large components, walls and structures. The Additive Manufacturing Marketplace has 34 concrete printing machines listed, ranging from desktop printers to large track mounted gantry systems that can print three or four story buildings. Companies making these machines are mainly from the US and Europe, and the table also has details on the type and size of a selection of machines. There are also several companies offering 3DCP as a service at an hourly or daily rate.

 

One of the most advanced 3DCP companies is Black Buffalo, a subsidiary of South Korea’s Hyundai group based in New York. Their NexCon gantry system takes around 11 hours to build and eight hours to take down. Using a proprietary ink developed over a few years of research involving a lot of trial and error (and getting approval for building codes), the machine can print up to four stories with a crew of five people. One person is required to monitor the nozzle and insert stiffening frames every few layers to provide structural strength, the pump needs two people and a helper, plus a site foreman or engineer. As well as walls it will print floors and precast elements. Black Buffalo expects to sell over 100 of these printers in 2022-23, and they are available for rent at $1,000 a day. 

Some companies making 3D concrete printers

Company	Machine and Sizemeters	Type	Cost in US Dollars
Black Buffalo United States	NexCon 1-1   3 story                        4 story	Gantry	$400,000 $750,000
COBOD Denmark	Bod 2 14.6 x 50.5 x 8.1	Gantry	$200,000 to $1m
Imprimere Switzerland	BIG 3D 5.7 x 6.0 x 6.2	Gantry. Prints large components	$1,757,000
ICON United States	Olympus 2.6 x 8.5 x 2.6	Gantry	$150,000
Constructions 3D France	Maxi Printer 12.2 x 12.2 x 7	Mobile robotic arm on 4 legs	$495,000
Luyten Australia	Platypus  6 x 12 x …	Gantry	$36,000
PrintStones Austria	Baubot	Mobile robotic arm on tracks	$150,000
Massive Dimension United States	MDPC 2 x 2 x 2	Fixed robotic arm	$80,000
CyBe Construction Netherlands	CyBe RC 3Dp 2.75 x 2.75 x 2.75	Fixed robotic arm	$205,000
MudBots United States	MudBot 3D Up to 22 x 22 x 15	Gantry	$35,000+
WASP Italy	DeltaWASP 1 x 1 x …	Robotic arm	$100,000+

 

Concrete printing is only one part of the development of additive manufacturing. In mid-2022 the Additive Manufacturing Marketplace listed 2,372 different 3D printing machines from 1,254 brands. The number of printers and materials used were: 364 metal; 355 photopolymers; 74 ceramic; 61 organic; 34 concrete; 24 clay; 20 silicone; 19 wax; and 19 continuous fibres. Many of these printers could be used to produce fixtures and fittings for buildings. Producing components onsite from bags of mixture avoids the cost of handling and transport, and for large items avoids the load limits on roads and trucks. There are also printing services and additive manufacturing marketplaces being set up. These link designers to producers with the materials science, specialised equipment and print farms capable of large production runs and manufacture on demand. Examples are Dassault Systems 3DExperience, Craft Cloud, Xometry, Shapeways, 3D Metalforge, Stratasys and Materialise. 

 

Additive manufacturing is a major part of a broader system of production known as digital fabrication. Neil Gershenfeld described digital fabrication as turning ‘bits into atoms and atoms into bits’ using fabrication laboratories (fabs) producing ‘assemblers’ that provide the cutters, printers, millers, moulders, scanners and computers needed for designing, producing and reproducing objects. These tools include traditional subtractive ones for cutting, grinding or milling, but the focus has been on research into new methods of additive manufacturing using different methods of layering materials using 3D printers. Printing of metal, ceramic and plastic objects from online design databases is spreading from hobbyists and initial users to industry applications and wider acceptance. Gershenfeld, who founded the first fab in 2003, defined digital fabrication, as ‘the seamless conversion of design and engineering data into fabrication code for digitally controlled tools.’ 

 

At is broadest, digital fabrication is any means of turning design information into physical products using automated processes. There is a well-established global maker movement behind the growth of digital fabrication. In 2009 the Fab Foundation was established at MIT as a non-profit with annual conferences and providing educations and training. The Foundation coordinates an international network of 1,500 fabrication laboratories (fabs) in 90 countries, many in university design and architecture schools, and the ‘FABLAB Movement’ is an even broader collaborative effort that includes hobbyists and tinkerers working on digital design and fabrication code. This network takes existing technologies used in fabrication like cutting, milling and rolling done by numerically controlled machines, which have been around for decades, but uses them for design, which is new. The digital linking of design to fabrication is the beginning of another stage of development. The World Economic Forum also has a network of 14 Centres for the Fourth Industrial Revolution, and Autodesk has three BUILDSpace laboratories. The 2017 UK industrial strategy included funding for a manufacturing hub and along with aerospace and automobiles targeted construction, 3D concrete printing and OSM. 

 

Gershenfeld argues digital fabrication will follow a similar exponential development path as digital computers, with the number of fabs doubling every two years and their cost halving, making local production of many objects and items possible. Gershenfeld suggests the technology is now ready to become widespread, and is at a similar stage to PCs in the early 1990s:

Digital fabrication shares some, but not all, of the attributes of communication and computation. In the first two digital revolutions bits changed atoms indirectly (by creating new capabilities and behaviours); in the third digital revolution, the bits will enable people to directly change the atoms …. Across the global network of fab labs, we can already see a steady stream of innovations around cost-effective models for individuals and communities to make clothing, toys, computers and even houses through designs sourced globally but fabricated locally.

 

Digital fabrication is at or close to the tipping point, as its use extends from hobby to experimentation and adoption. Just as concrete in the early 1800s moved from the fringe toward the centre of construction as the underlying technology and equipment improved, fabs can follow a similar path over the next few decades of the twenty-first century. Although adoption is limited and is not deployed at scale, the technology is advancing rapidly and many demonstration 3D concrete printing projects have been completed successfully. In a 2020 report that has many examples of current use, ARUP argues: ‘The opportunities unfolding with digital fabrication not only demonstrate new techniques in full-scale pavilion fabrication, but also provide new methods to solve design, business and societal challenges.  Arup is one of a number of specialized consultants providing digital twins and design to fabrication capability on projects. 

 

 

Onsite and Nearsite Production with Digital Fabrication

 

Digital fabrication is a technology whose use has a high probability of becoming ubiquitous. In construction, the focus so far has been on 3D printing of concrete, with experimental systems by the early 2000s, and by 2019 there were over a dozen examples of buildings completed using the technology.[i] However, the potential of 3D printing in construction is not limited to concrete. Once a BIM model of a project has been created it can be used to provide instructions for production of both structural and decorative components of a building. Mobile digital fabs in shipping containers can produce some of those components onsite. Local firms offering manufacturing on demand from print farms can produce large runs or specialised components, a nearsite form of production rather than OSM. 

 

The combination of digital twins and digital fabrication would be transformational if it allows onsite and nearsite production of some or many building components, by fundamentally altering existing economies of scale in the industry. As well as 3D concrete printing, other materials like steel and plastic can be used to make components and fittings on or near the building site. A modular fab in a container customised for construction, or even a specific construction project, can be set up onsite to produce components as the schedule requires. Large sites might need a fleet of fabs. Restorations and repairs can be done with replacement parts made onsite from scans of the original. 

 

Mass production will always have a role, but market niches currently occupied by some or many manufacturing firms may be replaced by new production technologies based on BIM, linking localised digital fabrication facilities with online design databases. Combined with robotic and automated machinery and assemblers, digital fabrication and standardised parts opens up many possibilities. Adding new materials to the 3D palette through molecular design and engineering, or upgraded versions of existing materials, may unlock other unforeseen design and performance options.

 

If this eventuates some, possibly a great deal, of the current construction supply chain based on mass-production of standardised components will become redundant. For example, an onsite or nearby fab with printers and moulders might produce many of the metal, plastic and ceramic fittings and fixtures for a building during its construction. These parts might be delivered by autonomous vehicles. The digital twin of the project, which might be outsourced, can link the design and fabrication stages to the site and the project. Digital fabrication produces components and modules designed to be integrated with onsite preparatory work and assembled to meet strict tolerances. Project management would become more focused on information management, and the primary role of a construction contractor might evolve into managing this new combination of site preparation work and integration of the building or structure with components and modules, some of which may be produced onsite in a fab if economies of scale permit. The strength of this effect will be determined by those economies of scale. Beyond site preparation other site processes may be restructured around components and modules that are designed to be assembled in a particular way, and machines to assemble those components and modules can be fabricated for that purpose.

 

If onsite and nearsite production becomes steadily cheaper the industry would, perhaps slowly, reorganise around firms that best manage onsite and offsite production and integration of digitally fabricated parts. Contracting firms would become more vertically integrated if they are fabricators as well, reinventing a business model from the past when large general contractors often had their own carpentry workshops, brick pits, glass works and so on. With outsourced business processes and standardized site and structural work, that fabrication and integration capability would be a key competitive advantage of a construction firm.  Firms will be integrating automated production of components with design and construction using offsite manufacturing and onsite fabrication, using platforms that coordinate building design and specification with manufacturing, delivery and onsite assembly. Open platforms will be like new digital ecosystems. Closed, internal platforms will be developed by larger, vertically integrated firms with the resources to manage the system.

 

Industrialised materials like concrete, steel and glass affected the organisation of onsite processes as they were improved with incremental innovations. The development of digital fabrication should follow a similar path to concrete, where over decades the machinery (mixers, pumps), processes (formwork systems) and materials (reinforcement, concrete strength, setting agents) were developed. Growth in digital technologies is faster than analogue, so instead of the many decades of innovation taken for concrete technology to develop, it might take a decade for digital fabrication to become cost effective if the cost of fabs falls and the supply chain of raw materials develops as it did for personal computers in the 1990s. Contractors would become more vertically integrated as they also become fabricators, managing a combination of onsite and nearsite production to deliver projects.

 

 

References

ARUP, Designing with Digital Fabrication, 2020: 8. 

Gershenfeld, N. 2012: 45. How to Make Almost Anything: The Digital Fabrication Revolution. Foreign Affairs,91(6), pp. 43–57.

Gershenfeld, N., Gershenfeld, A. and Cutcher-Gershenfeld, J. 2017: 7. Designing Reality: How to Survive and Thrive in the Third Digital Revolution, in New York: Basic Books., 

Sanjayan, J. G., Nazari, A. and Nematollahi, B. 2019. 3D Concrete Printing Technology - Construction and Building Applications. London: Elsevier.

 

Construction as a technological system of production: A life cycle approach

 Innovation and industry evolution

The stages in the life cycle of an industry typically start with first applications of a new invention by technology leaders, followed by development and refinement of products and services, before becoming a mature industry with well-understood products and practices. Mature industries are past the early growth phase, their culture of technology has stabilised and the shape of industrial structure and processes has emerged. In many cases these industries are oligopolistic, with a few specialised firms dominating market niches in the supply chain. Consolidation leads to concentration. 

The new technology that starts a cycle of industry development can be a general purpose technology (GPT) that becomes the basis of a new system of industrial production. The key feature of a GPT is ‘pervasiveness’, how it is used by other sectors in the economy and leads to ‘complementary investments and technical change in the user sections’ (Helpman and Trajtenberg 1998: 86).  The examples originally used by David (1990), and broadly followed since, were steam, electricity and information technology.  Lipsey, Carlaw and Bekar  (2005) include two organizational GPTs in their list of two dozen since 9000BCE: mass production and the factory system; and lean production and the Toyota system. It is widely believed AI is a new GPT.

Thinking about the construction industry and the production of the built environment as an evolving ‘system of production’ provides a new perspective on the context and direction of innovation and its evolution since the first industrial revolution. Hughes’ (1987) life cycle model had seven phases: invention, development, innovation, transfer, growth, competition, and consolidation. Within those seven phases of the life-cycle are two interior cycles that divide an industry’s evolution into two stages: Cycle 1 is invention, development, innovation, and transfer, Cycle 2 is growth, competition, and consolidation.

Cycle 2 focuses on innovation in production and organization, when mature technological systems emerge and construction materials like cement, concrete and glass, and components like building management systems, interior walls, plumbing fixtures, lifts and elevators have become oligopolistic industries in a mature supply chain. A mature industry produces a specific culture of technology, embodied in the firms and social institutions of the system of production, and creates the tendency for an industry to develop along defined technological trajectories unless or until deflected or disrupted by a powerful external force.

A diverse cluster of industries with deep layers of specialised firms in a dense network of producers, suppliers and materials is a ‘technological system’ (Hughes 1987: 47). Electricity grids and railways have networks, telecommunications and air traffic use interconnected nodes, postal systems use existing networks, some are geographically large, some are local, some are narrow, some broad.  

Construction innovation has been narrowly focused because construction is a mature technological system, but this is changing. With a technological trajectory based on AI and associated emerging production technologies, the commercial contracting part of the industry will adopt these technologies as they become viable. The organization and structure of the industry will then change in response to changes in relative costs as the economies of scale of digitized production technologies are realized.

AI as a new GPT may be the start of a new life cycle in building and construction technology, and may be as disruptive as steam power was in the nineteenth century to the master builders and craftsmen of the day. The organization of construction is currently centred on project managers and incremental innovation, but a transformed industry would be focused on integrators who combine site preparation with production and assembly of digitally designed and fabricated components and modules.

 

 

David, P. A. 1990, The Dynamo and the Computer: An Historical Perspective on the Modern Productivity Paradox‟, American Economic Review, Vol. 80, pp. 355 - 361.

Helpman. E. and Trajtenberg, J. 1998. Diffusion of General Purpose Technologies, in Helpman, E. (ed.), General Purpose Technologies and Economic Growth, Cambridge: MIT Press. 85-119.

Hughes, T. P. 1987. The evolution of large technological systems, in The Social Construction of Technological Systems: New Directions in the Sociology and History of Technology, W. E. Bijker, T. P. Hughes, and T. J. Pinch (eds.), Cambridge, Mass.: MIT Press.

Hughes, T. P. 1989. American Genesis: A Century of Invention and Technological Enthusiasm 1870-1970, Chicago: University of Chicago Press. 

Lipsey, R. G., Carlaw, K. I. and Bekar, C. T. 2005. Economic Transformations: General Purpose Technologies and Long-term Economic Growth, Oxford: Oxford University Press.

Construction Four

Industry Structure and General Purpose Technologies

A new general purpose technology (GPT) becomes the basis of a system of industrial production. For the construction industry and the production of the built environment, the emerging technologies collectively known as the fourth industrial revolution* will be transformative. 

Prior industrial revolutions were driven by steam in the nineteenth and electricity and computing in the twentieth century. Over this period the structure of the construction industry evolved through three stages, first from mediaeval master builders and craft guilds to contractors and tradesmen, then to the modern project manager-subcontractor structure. Interestingly, the transition to steam and the end of the guild system affected the organization of the construction industry far more than the ones to electricity and computers. With electricity, the organization of the industry evolved from contractors to project managers in a structurally, if not contractually, similar production system. And electricity did not affect on-site construction in the same way it did manufacturing, which needed to reconfigure factory layouts, because on-site steam powered machines such as cranes and excavators were replaced by petrol and diesel ones doing similar work. Computers and information technology have restructured office work everywhere, and affected industries like retailing, travel and entertainment far more than construction.

The adoption of steam power was an earlier experience of technological disruption leading to a restructuring of the construction industry. Steam power was a new GPT and industrial materials fundamentally restructured the industry from the craft-based industry of the eighteenth century. Over the nineteenth century this led to the emergence of the architectural, engineering and quantity surveying professions, and an industry structure of contractors and tradesmen for production. The three areas of construction that were transformed in the nineteenth century were identified in the eight case studies by Peters (1996) as industrialization, mechanization and organization:

1.  Industrialization of production methods with standardisation of components and mechanized mass production, and the development of new materials like steel, plate glass and plastics. This led to a new design aesthetic, with more modular components and internal services, and separated the envelope from the structure. The infrastructure of materials suppliers and equipment producers developed, and scientific R&D joined the industry’s traditional trial and error approach to problem solving.

2.  Mechanization of work based on steam power, with cranes, shovels and excavators common by the mid-1800s. This in turn led to a reorganization of project management, with the new form based around logistics and site coordination to maximise the efficiency of the machinery and equipment.

3.  Organization of the modern construction industry was developing by the mid-1800s. Large general contractors had emerged by the 1820s, undertaking projects on a fixed-price contract often won through competitive bidding. This system of procurement was supported by the new professions of architects, engineers and quantity surveyors, which were institutionalising in the early nineteenth century.

Automation and AI in the twenty-first century can be expected to work along these dimensions, as the fourth industrial revolution reconfigures them by linking data through the life of a project. The role of AI enhanced, cloud-based platforms that integrate design, production and delivery of components and materials with digital production technologies that allow mass customisation will be significant in the production of components and materials. Gershenfeld (2017) argues digital fabrication will follow a similar exponential development path as digital computers, with the number of fabrication laboratories (Fabs) doubling every two years and their cost halving, making local production of many objects and items possible. Gershenfeld, who founded the first Fab in 2003, suggests the technology is now ready to become widespread, at the stage PCs were in the early 1990s. If this exponential growth eventuates, much of the current construction supply chain based on mass-production of components might become redundant. For example, an on-site or nearby Fab with printers and moulders might produce many of the metal, plastic and ceramic fittings and fixtures for a building. 

For mechanization, the characteristic changeability of construction sites is challenging for automated and robotic systems, and it might take decades of investment for machines able to do site work or for humanoid robots to do human tasks. In some case a human supervisor operating a team of robots or several pieces of equipment, each with limited autonomy, might work better. A worker with a smart helmet could monitor these machines both on the project and in the site model. Beyond site preparation however, there may not be many tasks left if site processes are restructured around components and modules that are designed to be assembled in a particular way, and machines to assemble those components and modules can be fabricated for that purpose. For an industry with an aging workforce there are exoskeletons for site work, a form of human augmentation beginning to be used in the aerospace and automotive industries.

Digital platforms providing building design, component and module specification, fabrication, logistics and delivery will become widely used. Platforms provide outsourced business processes, usually cheaply because they are standardized, and are available to large and small firms. Also, platforms use forms of AI to monitor and manage the data they produce, the function of intelligent machines. Examples are Linkedin (matching jobs and people), Skype (simultaneous translation of video calls), AWS and other cloud-computing providers, and marketing, legal and accounting software systems. If these digitised business processes are cost-effective and become widely used, they can provide much of the data needed to train machines as project information managers.

The BIM model of the project, which might be outsourced, can link the design and fabrication stages to the site and the project. In 2019 the International Standard 19650 was released, providing a framework for creating, managing and sharing digital data on built assets. Digital fabrication produces components and modules designed to be integrated with on-site preparatory work and assembled to meet strict tolerances. Project management would become more focused on information management, and the primary role of a construction contractor could evolve into managing a new combination of site preparation work and integration of the building or structure with components and modules, some of which may be produced on-site in a Fab if economies of scale permit. In this case, the industry would, perhaps slowly, reorganise around firms that best manage on-site and off-site integration of digitally fabricated parts. With outsourced business processes and standardized site and structural work, that would be a key competitive advantage of a construction firm. Firms would become more vertically integrated if they become fabricators as well, reinventing a business model from the past when large general contractors often had their own carpentry workshops, brick pits or glass works and so on.

Dimensions of construction industry development

Technological developments are combining intelligent machines with engineered materials, deep learning capabilities, human augmentation and new organizational concepts, and are pushing against established custom and practice in a mature technological system. Because the system is mature the effect of new technology and the changes it brings could spread slowly across the industry as a whole, and unevenly because of the many small and medium size firms. While this was case with twentieth century GPTs like electricity, a period of disruptive change in the construction industry occurred during the second half of the nineteenth century, and a new system of production eventually resulted in a new form of industry organization led by contractors instead of architects and engineers. That disruptive transition took several decades, as industrial materials replaced craft ones and site work was mechanized and reorganized. Then, over the twentieth century contractors evolved into project managers and the traditional trades became subcontractors.

Large contractors delivering major projects ended up at the core of the construction technological system at the end of the twentieth century. By this stage the technological system had a clear outline, and a very clear structure, for bringing together the products, suppliers and materials needed for building and engineering projects, and had stabilised around particular forms of procuring, financing and managing those projects.

With a technological trajectory for industry based on AI, digital fabrication and associated emerging production technologies, the view taken here is that there will be a transition period of perhaps a decade, possibly two, as the commercial contracting part of the industry adopts these innovations. As that happens the organization and structure of the industry will also change, from one centred on project managers to one based on integrators that combine site preparation with production and assembly of components and modules. AI as a new GPT may be as disruptive as steam power in the nineteenth century, and lead to a similar restructuring of the industry. Neither electricity nor computing had a significant effect on the organization of the construction industry, because the evolution of the industry from contractors and trades to PMs and subcontractors was not driven by those technologies. However, the change from master builders and crafts to contractors and trades was a break from the past, and the result of industrialization and mechanization.

* This imprecise concept has been popularized by the World Economic Forum, following David (1990). Their description is: “The First Industrial Revolution used water and steam power to mechanize production. The Second used electric power to create mass production. The Third used electronics and information technology to automate production. Now a Fourth Industrial Revolution is building on the Third, the digital revolution that has been occurring since the middle of the last century. It is characterized by a fusion of technologies that is blurring the lines between the physical, digital, and biological spheres.”

 

 References

David, P. A. 1990, The Dynamo and the Computer: An Historical Perspective on the Modern Productivity Paradox, American Economic Review. 80, 355 - 361.

Gershenfeld, N. 2017. The Science, and The Roadmap, in Gershenfeld, N., Gershenfeld, A. and Cutcher-Gershenfeld, J. Designing Reality: How to Survive and Thrive in the Third Digital Revolution, in New York: Basic Books. 95-116, and 159-182.  

Peters, T. F. 1996. Building the Nineteenth Century, Cambridge, Mass.: MIT Press.