Concrete 3D Printing

As 3D printing, also known as additive manufacturing, continues to revolutionise a growing number of industries, Sephaku Cement explores how Concrete 3D printing is put to task in architecture and construction. Having already successfully created a number of prototypes and extremely technical products such as the intricate parts used in aerospace and aviation, as well as medical products including implants and artificial organs, 3D prints continues to pave the way as manufacturing and production marches into the 4th industrial revolution.

There are three common methods used in 3D printing technology, these include;

• Fused filament fabrication (FFF) or fused deposition modelling (FDM) which makes use of plastic materials that are heated and then pressed through a nozzle while following a pre-mapped design path
• Stereo-lithography (SLA) makes use of UV light to cure resin type materials one layer at a time
• Selective laser sintering (SLS) is more commonly used in industrial production and uses lasers to fuse powdered materials together one layer at a time.

From the design to the engineering and manufacturing, concrete 3D printing technology offers an efficient and cost effective alternative in the construction of a number of concrete applications. While initially limited to the use of molten plastic and metals, as 3D printing tech continues to advance, alternative materials are being employed including the likes of cement/concrete.

While concrete 3D printers are fairly significant in size especially for the construction industry, their mobility allows for basic concrete construction printing to occur almost anywhere and under various types of conditions.

Making use of a method similar to the Fused Filament Fabrication (FFF) or Fused Deposition Modelling (FDM) mentioned above, concrete 3D printing takes place using an automated and repetitive methodology that directs the print head through a sequence of rotations. While designs may still be a little basic and limited to more modest forms, concrete 3D printing can be extremely effective in the construction of high density, low cost housing in areas of high demand.

Basic Steps in the Concrete 3D Printing Process:

• As with any construction project, contractors begin by flattening the subgrade surfaces and placing sound foundations to work from.
• Once the foundations are in place, 3D printing technologists map the repetitive route that the 3D printer will follow using rail-like pathways that mimic the design. The 3D printer is then secured to the pathway rails and further guided by pillars for additional reinforcement.
• Once the design has been finalised and the printer’s route mapped out by the rails, a premixed concrete truck is connected to the 3D printer nozzle. The concrete mix used must be both fast curing as well as easy to pour, bonding to each layer as the concrete mix is pressed out of the printer. Making use of both superplasticizers as well as reinforcing fibres the ideal concrete mix can be achieved with the correct blend of chemicals and additives combined in the concrete
• The concrete 3D printer is now ready to begin following its repetitive path along the guiding rails depositing the exact amounts of concrete mix layer on layer.

With some concern that these concrete construction “bots” may eventually replace their human counterparts, concrete 3D technology is not without its shortfalls, although exciting technology is but only in its infancy, and will need much more development in future and will never fully replace the hand of construction contractors, workmen and architects.