Innovative Worksites: 3D Concrete Printing Is Redefining Construction

3D concrete printing is deemed the future of habitat for humanity. An overstatement? Think again—by 2060, 230 billion square metres will be needed to shelter our new fellow citizens, or the size equivalence of Paris multiplied every week over a 40-year period. 

If you’re looking for more concrete proof—no pun intended—note that between 2011 and 2013, China used more concrete than the United States ever did during the 20th century. 

To shelter everyone without completely compromising the planet in the process, the construction industry is counting on the development of new materials, but also on a material made with cutting-edge technology: 3D concrete. 

What’s 3DCP or 3D concrete printing?

3D concrete printing is a new technique that promises at least three things:

• Customization

• Productivity 

• Environmental performance 

To effectively carry out this process, a nozzle fitted onto a robotic arm is guided by instructions provided through computer-aided design software, pouring layer by layer of concrete. While the process was invented in the 1980s, the thought of using it to build a house, let alone a building, wasn’t even on the horizon.

Why's that, you ask? Teams of researchers had to test the materials’ performance beforehand, most notably to ensure the concrete produced was strong enough to ensure the following:

• Interlayer bonding

• Extrusion

• Stability, solidity, and rigidity

• Structural integrity

To put it differently, to do so, they first had to find a concrete recipe suited to 3D printing constraints.  

Workings of a Concrete 3D Printer

There are numerous 3D printer types. However, generally speaking, concrete printers work according to the following principles:  

• a gantry system supporting the 3D printer;

• computer-aided design software;

• printhead connected to a cement mixer; and

• the printer and printhead move along the X, Y, and Z axes to create the intended shape.

Preparing the CAD File

This consists of an iterative method known as “virtual prototyping,” which uses tools to measure the following:

• Thermomechanical structure 

• Fluid mechanics

• Electromagnetics

• Rheology 

A computer-aided design (CAD) is used to determine defects in the concrete in real-life scenarios and fix them to obtain a material that’s as resistant as possible. To do so, the model must be:

• Predictable

• Modifiable

Predictable in the sense that it has to evaluate the behaviour of concrete in “real-life” scenarios and modifiable as value alterations will pave the way to practical solutions. 

Once the CAD file is ready, it’s linked to a 3D printer and translated into a G-code, which instructs the nozzle (printhead) on how to carry out the correct motions. 

Layer by Layer Printing

The robotic arm that moves the printhead will pump the concrete, extruding it into lines, layer by layer, to create the desired shape. To build walls directly on-site, the production unit is directly hooked up to a gantry.

The gantry allows the printer to move on the X (horizontal) axe, while the printhead moves along the Y (horizontal) and Z (vertical) axes. That said, you can probably gather that these printers are quite sizeable. For example, ICON’s 3D Vulcan II printer is:

• 2.5 m high;

• 8.5 m wide; and

• weighs 1.7 tons   

It’s a far call from the standard home printer. 

Do you need a mould to hold up the structure during extrusion?

Not necessarily.

We’ll touch on this matter later on in the article, but for now, let’s just say numerous techniques are used to 3D print concrete. One of these consists of maintaining the extruded material with a gel set in a mould. 

The concrete holds up through suspension while the mould serves as framing until it hardens.

Other methods have been developed, such as those deemed more conventional, relying on a framework, while others have done without. We’ll revisit this factor in the section dedicated to 3D-printed projects done around the world. 

Materials Used to 3D Print Concrete

The material used to 3D print concrete is fundamental in further developing this cutting-edge technology. Here’s what you need to know about its composition. 

Selecting Concrete for 3D Printing

The concrete used to 3D print isn’t quite like the standard concrete you might come to spin in your cement mixer in your backyard. This concrete, albeit made with all the fundamentals of concrete (cement, sand, aggregates, etc.), must be adapted to adhere to the following: 

• 3D printing criteria (extrusion, flowability, stability, rheology); 

• workability; and 

• constructability. 

As such, it doesn’t have identical characteristics as traditional concrete.  

Characteristics of the Concrete Used

To build houses or buildings with 3D-printed concrete, teams of researchers started with standard Portland cement but added even more cement to the concrete mixture. 

However, adding more cement does present a significant downside: it negatively impacts the environment as the production of concrete is a direct result of greenhouse gas emissions. 

Therefore, to construct a sustainable habitat for humanity, you have to significantly reduce the amount of cement needed to manufacture 3DCP. To do so, alternative materials can be used:

• Geopolymer 

• Limestone calcinated clay cement

• Wattle and daub 

3D Concrete Printing in the Construction Industry

3D concrete printing is a construction industry breakthrough, redefining standards in terms of speed, efficiency, and durability. This innovative technology offers a plethora of advantages that transcend traditional construction methods.

The Advantages of 3D Printing for Home Building

From lowered costs to the possibility of constructing complex architectural structures, 3D printing is a glimmer of change within the construction industry. Whilst looking into the benefits of 3D printing for home building, we’ll also delve into the economical, ecological, and architectural aspects that make this initiative a game-changer when it comes to modern construction. 

1- Sustainable concrete practices 

Sustainably using this material was made possible by topology optimization. It’s a by-product of a digital mockup, in which the topology is used to determine the ideal volume of concrete to spread to construct a given shape with specific mechanical constraints.  

Topology optimization allows for the sustainable use of a material at the following rates:

• 80% for space truss walls (2 parallel plans of interconnecting bars); and 

• 70% for funicular flooring systems.

2- Quick configuration

In terms of a swift configuration, it’s a fact. We’ll give you examples from past projects, which we’ll present in detail later on in this article. However, note that some companies can erect house walls in under 24 hours, which is a 95% time gain.  

However, even if 3D concrete is quick to configure, its preparation is quite time-consuming. Two key factors are involved:

• lack of professional knowledge; and 

• lack of task-specific training.

Building a home using 3D concrete requires one to master 3 areas of expertise: 

• Digital

• Machinery

• Material 

To this day, few companies can master all three components perfectly. This technique is still new, its production is still mildly mastered, and there are still a lot of different methods used to erect walls (for example, with or without a framework).

3- Cost-effective technique

It’s a logical outcome. On one hand, companies will start specializing in 3D printing, rendering its preparation much faster. And on the other hand, having the ability to build house walls in under 24 hours is simply incredibly labour-efficient.  

Construction worksites will be 95% faster, thereby drastically lowering the total cost of construction. Moreover, companies will be able to lower their prices by multiplying their yearly worksite count. 

4- Environmentally friendly

Naturally, it’s not a silver bullet, but 3DCP will reduce environmental impacts by 32% compared to standard concrete. However, since not all types of concrete share the same ingredients or identical quantities, one has to be more accurate. 

Therefore, if we were to compare standard C25/30 concrete with high-performance concrete (developed by ETHZ IFB), the latter is 40% more detrimental to the planet per cubic metre compared to standard concrete. 

On the flip side, if you consider compressive force, high-performance concrete is 20% less hazardous to the environment per MPa than traditional concrete.

In other words, the global environmental consequences of 3DCP are, as a whole, positive, but one has to remain wary of the numbers and not take them for granted. 

5- Mass customization

After the Second World War, Europe saw a trend in mass-customization housing. Architects were redefining design to meet the requirements of mass production. Swiss-French architect Le Corbusier even played around with serial housing, a concept that was perfectly brought to light by Phénix houses, standardized and affordable housing. 

With 3D concrete printing, it’s a whole paradigm shift, moving from mass construction to mass customization. Today, the prospective homeowner simply needs to voice their vision for their future home for it to be integrated into a digital mockup. 

This technique is beneficial as it doesn’t impose additional costs for customization or extend real estate project timelines. It’s the manifestation of Deleuze’s theoretical intuition, defined through the “objectile” in his book The Fold: Leibniz and the Baroque. 

This means that 3D concrete printing allows for mass production development of non-standardized goods.  

What’s the primary drawback of 3D printing?

It’s an entirely new technology, meaning concrete’s long-term life cycle remains unknown. What’s for sure though is that 3DCP has 2 major potential pitfalls:

• shrinkage-related fissures; and 

• quality inconsistency. 

In fact, 3D concrete struggles to meet construction standards, most notably in terms of mechanical resistance. All that is due to its difficulty in producing quality printable concrete.

It’s also the reason why public authorities are struggling to standardize the use of 3D-printed concrete in regulations governing the construction industry. As of now, it’s strictly limited to experimental projects. 

The Challenges of 3D Concrete Printing

3D printing requires merging opposites. To effectively use a 3D printer, the concrete used must be:

• Extrudable

• Stable

Yet: 

• Flowable

• Sufficiently viscous

In other words, the concrete has to be sufficiently fluid to move throughout the pump to be ejected through the nozzle fitted onto the robotic arm. At the same time, it has to be viscous enough so that the layers of concrete don’t crumble beneath one other from the weight.  

To do so, the material has to be kept in motion at the right speed to maintain its viscosity until it’s shot from the nozzle. Then, thixotropy comes in, meaning once the motion is halted, the concrete should cure. 

With optimal motion speed, concrete will have the necessary specifications needed to construct a house or building. Otherwise, the slightest lack of precision could lead to catastrophic results. Creating both a robust concrete and quality printer is a challenge that was taken on by Professor Ammar Yahia and his students at the Université de Sherbrooke. Vying with them are leading material providers, like Lafarge, that already have a head start. 

Examples of 3D-Printed Concrete Projects

This technique is part of the construction industry’s technology showcase, so much so that its use has led to a literal global race. As such, back in 2018, France was the first to build a 3D-printed concrete house. However, it wasn’t until the first semester of 2022, and four years of research, that five individual houses were built without a framework.  

In the United States, the first 3D concrete printed house was built in September 2022, in Houston. Here, the Americans' ingenuity led them to merge 3D concrete with wood framework, thereby adhering to the North American construction style. 

A three-month building timeline was shaved off and 50% less materials were used on these construction sites.  

Building towers aren’t on the menu yet. Teams of researchers at the forefront of the innovation are currently able to construct two-storey buildings but still struggle to build three or four stories. So, in terms of seeing the first 3D-printed building towers, we’re not out of the woods just yet.

When it comes to this particular sector, the Germans are ahead of the game, having built a three-storey building courtesy of manufacturer and supplier PERI in 2020 (a 6-week on-site process) in Wallenhausen, then a 9-metre tall, 54-metre long, and 11-metre wide building in Heidelberg. 

The Use of 3D-Printed Concrete in Canada

In Canada, the Université de Sherbrooke is at the head of the industrial revolution. Led by Ammar Yahia, NSERC Industrial Research Chair for the development of flowable concrete with adapted rheology, Université de Sherbrooke is striving to make up for the country’s delayed progress. 

To accomplish such a feat, civil engineering departments are attempting to build structures entirely from 3D-printed concrete. Not only is it highly likely that this goal will be achieved, but we may be able to take the lead over our neighbours to the south and our cousins across the pond. 

Why’s that? Because the 3D concrete printing industry relies on techniques for which the best approach has yet to be discovered. Proof’s in the pudding—there are over a dozen 3D printing methods, of which, the following are the most common:

• Contour Crafting (University of Southern California);

• Loughborough University’s 3D concrete printing system; and

• D-Shape (developed by UK-based company Monolite).

Professor Ammar Yahia and his team aren’t looking to put an end to their efforts. They’re hoping to use this method to repair bridges and dams in hard-to-reach areas. 

Université de Sherbrooke, which already developed its own 3D printer, could also, one day, establish a printing method. 

Local competition is tough in and of itself, as the RI³D-FRQNT (Regroupement innovant pour l’impression d’immeuble durable), which was created by a teacher at the Cégep de l’Abitibi-Témiscamingue and given $900,000 by the Fonds de recherche du Québec, is also hoping to create the first 3DCP modular building in the country. 

The Future of Construction Is Shaped by 3D-Printed Concrete

3D concrete printing is shaping itself to be a groundbreaking revolution in the construction industry. The details brought to light, such as its configuration speed, design customization, waste reduction, and durability are carving out a future in which this technology could be a vital asset in how houses are built. Although there are still some drawbacks, the constant progress being made as well as projects completed are a telltale sign that 3D printing is a path worth paving.  

FAQ About 3D Concrete Printing

How much does 3D concrete printing cost?

First, the two scenarios have to be distinguished:

• purchasing a house; or

• a company investment. 

With the first scenario, construction costs would be curbed by an estimated 10% to 20%, which is rather favourable to the buyer.

As for the second scenario, a company looking to invest in a large-scale 3D printer would have to dish out about $250,000. However, costs may be trimmed by investing in smaller machines, which run at about $50,000.

To that, add the costs of accessories like the concrete pump and mixer, as well as the project-specific expert salaries. 

How can you make a 3D print stronger?

Everything hinges on the concrete recipe. Based on the ingredients used, dosage, and speed at which the concrete is rotated during road transportation until it’s poured will determine its strength. 

Therefore, making a 3D print stronger means having the whole set of necessary skills to master this production tool. 

We mentioned the specific characteristics of 3D-printed concrete, all of which contribute to its inherent strength.

How thick is a 3D print?

In the field of 3D concrete printing, the minimal wall width depends on the following: 

• the thermal resistance needed; 

• the mechanical resistance required; and

• the load-bearing capacity.

In other words, the width directly depends on the real estate project and the pertaining regulations. 

The Future of 3D Concrete Printing in Construction

3D concrete printing generates a lot of interest regarding its potential in the construction industry. The elaborated prospects, including configuration speed, cost and waste reduction, as well as diverse uses, all pave the way to a technology redefining the way we’re building. Albeit the lingering technical and regulatory challenges, the breakthroughs and pilot projects reveal the true potential of this construction method. By further exploring this technology, we could potentially see an era during which 3D-printed concrete becomes a pilar of construction, providing innovative and sustainable solutions for future architectural and urban projects.