Zoey Zhao | Construction Executive
The construction of buildings using concrete has been around since the time of the Romans. In all those centuries, concrete structures have been built using essentially the same method: forms, reinforcement, mixing, pouring, setting, repeat.
The process is costly and time-consuming. The construction of the forms alone demands dozens of workers and requires a substantial amount of lumber, keeping labor and materials costs high. Builders might save some time using prefabricated concrete blocks, but such materials are not appropriate for every construction project and carry their own expenses.
For the first time in history, builders have an alternative to traditional concrete construction methods that are more cost-effective, less expensive, more environmentally friendly and allow for a wide range of possible construction projects. Three-dimensional concrete printing for construction has emerged in the building field as a viable and efficient alternative.
THE BASICS OF 3D PRINTING
3D concrete printing is simple in theory: software controls a three-dimensional locating system that moves a smart concrete pump that extrudes a special type of concrete. The printer dispenses the concrete one layer at a time, layer upon layer, producing a concrete form. Forms manufactured this way are incredibly accurate to the original design.
In this way, 3D concrete printers are like smaller, resin-based 3D printers; they just accomplish the task on a larger scale. The larger scale of 3D concrete printing used in construction is made possible by the three-dimensional locating system that moves the injector. There are two types of such systems: gantry and robotic arm.
Gantry Systems
Basic models use a gantry structure on which the injector is mounted. As the injector moves back and forth along the gantry framework, it “prints” the concrete mixture according to the programmed instructions. This technology allows the creation of custom-designed buildings, requiring neither costly construction forms for poured concrete nor aesthetically unappealing designs for concrete block. 3D concrete printers are capable of design flexibility at a low cost.
That is not to say that these gantry systems do not have their own limitations. The construction of the gantry itself requires a good number of labor hours to assemble and disassemble and the use of a crane to do so. In addition, moving the gantry contributes to overall transportation costs.
Robotic Arm Systems
Other 3D printing companies use robotic arm-based systems that solve some of the problems associated with gantry systems. Robotic arm systems provide all the benefits of gantry-based 3D printing while saving time and resources. Robot printers move along a track, and their three-meter-long arms have a wide range of lateral movement. In addition, in combination with a scissor lift, these track-based robotic systems can offer the same construction heights as gantry systems. Moreover, robotic technology is widely used throughout several different industries, meaning the control systems are more reliable, easier to scale and easier to maintain.
A MATERIAL ADVANTAGE
Despite the obvious difference in construction methods, perhaps the most significant difference in using 3D concrete printing is in the materials needed for building.
The concrete mixtures are engineered to provide both strength and adaptability, allowing for dynamic design and sturdiness.
The strength of the mixture is due to the unique blend of materials used in the printing process. The extrusion is made using a mix of concrete/cement, wax, foam and polymers, and this mixture allows the concrete to be shaped as desired without losing strength.
The powder bonding process employs polymer and reactive bonds to make the mixture solid through the sintering process. Moreover, these unique materials make the additive welding process possible—a process essential to the layering method of 3D printing.
In addition to the revolutionary nature of these materials, the 3D printing process reduces the need for more traditional ancillary materials used in construction. Because frames and reinforcements are unnecessary for 3D printing construction, there is no longer a need for lumber and rebar as essential construction materials.
BENEFITS
3D printing construction technology has existed for years but previously was relegated to “experimental or novelty” projects. However, recently contractors have been more willing to employ this technology in projects long dominated by traditional construction methods. This shift has been made possible by a growing recognition of the benefits of 3D concrete printing technology.
Faster and More Affordable
A large percentage of construction costs are due to the shortage of skilled labor. 3D printing technology in general, and robotics-based technology in particular, helps the labor force to be more productive. Increased productivity, in turn, results in more efficient jobsites, less building time and overall cost savings.
In addition, the savings in materials is matched by a savings in time. Using 3D printing, a contractor can produce a modestly sized building in weeks rather than months. Builders using this technology finished a park consisting of more than 2,000 concrete pieces in just two and a half months, at a fraction of the cost of conventional construction methods.
These reductions in time, personnel, and material costs can reduce overall production costs by as much as 34% for a wood-built building and 37% for a CMU concrete block structure. In addition, because the simulation stage allows designers to solve technical problems before they arise in construction, logistical and planning costs are much lower than traditional building methods.
Sustainability
3D printed concrete does not need formwork, usually made from wood and wasted after use. This method prints concrete only in the required places calculated by an algorithm, reducing the usage of carbon-heavy cement. In addition, the sand that makes up almost 50% of the concrete can be sourced locally, saving on transportation costs and carbon emissions associated with transportation.
In a market increasingly driven by environmental and sustainability concerns, these benefits help contractors maintain a competitive edge while meeting critical societal goals.
Safety
Robotic construction technologies, such as 3D printed concrete, provide workers with a safer and healthier working environment because robotics do the heavy lifting.
Dynamic and Beautiful Shapes
The gantry-based three-axis construction system is more dynamic than many traditional construction methods. Robotic six-axis modular arm-based systems are even more adaptable. In addition, proprietary building material outperforms traditional concrete, producing far more diverse and fluid shapes at no additional cost. This method makes it possible to create attractive and stylish design elements without the expense usually associated with premium designs.
Benefits to the Public
The 3D printing construction process allows for creating public works at a substantially reduced cost. Contractors using 3D concrete printing can submit bids at highly competitive rates.
FUTURE
What was once a novelty has been making steady gains in the construction industry. This new technology has been maturing and growing. The addition of robotics as an alternative to gantry-based systems represents an evolution in the technology that will make it not only more affordable but more dynamic and more desirable.
The technology will also allow for cross-industry applications. Contractors, builders and designers alike are excited to see these robots not only doing 3D printing onsite and offsite for construction but also supporting different trades using different tool heads.
In an age when housing costs, environmental crises and labor shortages present real challenges for the construction industry, new technology offers a hopeful solution.
The future of construction, it turns out, is printed.
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