3D printed concrete reinforcement is a mechanism where the tensile strength and ductility of 3D printed concrete are improved using a vast range of reinforcing techniques, including reinforcing meshes, cables, bars, or fibers.
3D printed concrete reinforcement is vital for the large-scale application of the new technology. The anchorage and reinforcement technologies vary significantly. For non-structural elements, the application of non-structural reinforcement like fiber reinforcement is not unusual.
So, how Are 3D Printed Houses Durable Without Steel Reinforcement? 3D Printed houses are durable without steel reinforcement by optimizing the design shape, limiting height, and using; mesh or fibers, or external anchors.
Early research in concrete 3D printing technology mainly focused on developing material technologies of the concrete/cementitious mixes. Concrete material extrusion-based printing is currently preferable both in terms of cost-effectiveness and availability of technology. Therefore, most of these reinforcements currently under development or already developed are fit for the extrusion-based 3D printing technology.
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Types of 3D printed house reinforcements: Why it can be done without steel
Just like in conventional concrete, reinforcement in concrete 3D printing can be classified based on either the method of action or the method of placement. The methods of reinforcement placement are co-installation, post-installation, and pre-installation. Examples include pre-installed meshes, post-tension cables, and fibers mixed with concrete.
Examples of passive and active reinforcement in 3D printed concrete are post-tension cables and reinforcement bars used to prestress segmental elements. Most reinforcement in concrete and 3D printed concrete has conservatively been steel.
Common reinforcements in 3D printing
Also, popularly used as a passive reinforcement technique, reinforcement meshes involve the use of welded wire meshes that are laid in-between the slabs printed layers without the need of any network. Reinforcement meshes can also be used in printing wall elements fabricated and erected in place.
Unlike the rebars method, spools of meshes are simultaneously unwound ahead of the 3D printer nozzle in order to provide both vertical and horizontal reinforcement to the printed elements. This method also compensates for missing framework in the fresh concrete state, on top of acting as a reinforcement in the hardened state.
Reinforcing steel bars
The popularity and high availability of rebars or deformed bars as a passive structural reinforcement method in a conservative concrete system make this reinforcement sought after in a 3D printer concrete. They are erected in order to reinforce cages, where concrete is printed to form beam and wall elements. This makes the rebars, an effective strategy for pre-installation.
You can also install rebar cages inside printed concrete form works with non-structural members and fill the holes with grout. This is a post-installed reinforcement that has proved to be very cost-effective. However, attention to the interface between the printed concrete and steel is required
Including fiber in the mix gives a vast range of merits, like in the case of conservative concrete. The faster rate of hydration and the higher cement content requirements of the printed concrete makes it prone to thermal stresses and shrinkage cracking. The use of fibers (non-structural and structural) can help counter these quite well. Fiber reinforcements can also be used to print shell structures, as converting bending moments into an axial force requires high and tough stiffness concrete.
When aligned properly, fiber can provide this required higher stiffness and toughness. You can also enhance the flexural tensile strength with the addition of PVA fibers or structural steel. All these properties make fiber-reinforced concrete a more suitable material for 3D printing form works. The concrete cohesiveness in the fresh state, very crucial for planning, can be enhanced by using non-structural fibers like basalt or polypropylene.
External anchor connectors
These reinforcements are installed in truss elements in order to connect them to similar units by means of exposed thread bars. This technique ensures the faster fabrication of lightweight units. The exposed reinforcement is likely to face corrosion when installed in an outdoor environment.
The durability of 3d printed houses
3D printed homes are becoming popular daily. However, some people still remain wary of the durability and quality of some 3D printed houses. Are 3D printed houses durable? Are they reliable?
3D printed homes are more durable compared to other construction methods, mainly because of the materials used. 3D printed structures are mainly made using concrete. When we talk about 3D printed houses, you may imagine that we are simply printing the plastic panes with the regular 3D printers. However, this is not the case with 3D printed houses. All 3D printed homes are created using concrete. Concrete material is highly durable, hence structures made from them can last decades with good maintenance.
For instance, concrete blocks typically last for at least 100 years. 3D printed houses on the other hand are expected to last for almost the same duration, depending on the material mixture or the type of reinforcement used.
Risks and potential ways to overcome it
3D printed houses are printed one layer at a time. Every subsequent layer added is printed on the previous one until you achieve the desired shape. In case a layer does not stick well to the previous layer laid, the inadequate bonding may cause a break or simply cracks between the layers. However, you can add the strength and durability of your 3D printed structure by bumping up the infill density, improving the wall thickness, setting up reinforcements, and increasing the number of walls for the structure.
This does not mean that 3D houses are not safe. 3D houses are safe enough to withstand most additional forces. You can trust your 3D printed house to withstand fires, and earthquakes among other forces.
Places where it’s a must, such as California (due to earthquakes)
3D printed houses can be designed uniquely to withstand tremors (earthquakes), impacts (debris), and sustained force (hurricanes). You can build strong structures capable of withstanding very strong winds, floating in floods, and even cheaply and easily movable.
3D printed houses are practical, affordable, and capable of withstanding earthquakes. This has seen the technology being applied in places more prone to earthquakes, such as California.
For more on Earthquakes and 3d printed structures, check out our post titled “Can 3D Printed House Withstand Earthquakes? Design and Foundation Limitations“
While it may sound like a movie you are watching, it is very much real that you can 3D print a house. 3D printed houses are strong and durable, just like the blocks and mortar structures. Some experts in this field have even argued that 3D printed structures are more durable compared to other models since you don’t require the use of rebars, which are prone to rust over time. While some 3D printed structures are fortified with rebar, it is not a commonly used material for this process.
While we may have a few challenges with 3D models, 3D printed houses offer a vast range of advantages compared to other regular models. 3D printing technology not only allows faster construction and greater versatility, but it is also environmentally friendly, and more cost-effective compared to other modes of construction.