The concept of 3-D printing is nothing new, but its promise makes it one of the biggest potential technologies for the construction industry. When it comes to creating a concrete structure, the term is actually an umbrella name covering different methods that involve constructing a product without the use of a form. Here are two common methods that allow designers to run wild with their imagination.
Binder Jetting 3-D Printing
One strategy involves the binding of particles by pumping paste or water onto a bed of fine aggregates and cement. After a layer of binder is created, another layer of aggregates is raked over and the process repeats until the structure is built, layer by layer. The product is held together by unbound aggregates while the paste hardens. Then, all the excess aggregates are brushed or blown away. One main benefit of this method is it offers a high level of control of the product’s shape. By layering the product with aggregates, the operator does not need to worry about the product’s self-weight causing deformation as it is being built up.
Concrete Extrusion 3-D Printing
Another strategy is the extrusion of wet concrete by a printer into a free-standing structure. This method also involves creating layers. However, there are two challenges faced when using this strategy:
- Designing a printer capable of extruding the mixed concrete
- Ensuring the concrete is stiff enough to stand under its own weight so it does not shear or fail
In addition, aggregates can sometimes get stuck in the printer and damage the internal workings. Using a mix design that is not too wet or flowable is important for holding the product’s shape.
Printers used for both methods can range from small desktop devices used for prototyping to large devices capable of building an entire house. One drawback faced by 3-D printers is it can take a long time to construct a product.
What does this all mean for the precast concrete industry?
While we are unlikely to see any major impact in the near future, it is important to be mindful of the research, progress and results around this new technology. As the printers, processes and products become more refined, the potential impact on both custom and standard precast concrete products could be significant.