Over the last decade, building structures 3D printing has been implemented by some pioneers around the world. An overview of the building structure 3D printing in the industry is summarised in table 1 shown below.
Table 1. Industry Review of building structure 3D printing
Winsun New Materials, a leading 3D concrete printing company in Chinese market, has launched its 3D printed houses since 2014 when it 3D printed 10 single-storey houses within 1 day. Subsequently, it also printed a luxurious villa of 1100 m2 and a multistorey apartment with a floor area of 865 m2. Although it has been extended to many storeys, all components of these projects were prefabricated in factories and then transported and installed manually on-site, showing few advantages over its conventional counterparts which are prefabricated in factories using formwork . On one hand, transporting pre-fab components induces additional costs. On the other hand, the assembly process consumes time, requires labour work, and compromises the integrity of houses. In other words, technically speaking, they are prefabricated buildings, as opposed to 3D printing construction.
In 2021, as reported by the Guardian , Europe’s first fully 3D printed house in Eindhoven, Netherland received its tenants, but similar to what was done by Winsun, neither is it on-site 3D printing construction technically.
PERI, a German-based company, on-site 3D printed a two-storey house of 160 m2 in Beckum but it necessitated manual trimming, and manual steel reinforcement and pipeline installation. It should be noted that overhanging parts, such as rooves and floors, remained prefabricated and on-site installed, and the 3D printing of overhanging components is one of the key obstacles in building structures 3D printing.
However, Mighty Buildings, a US-based 3D printed prefab company, is specially mentioned because it has solved many important industrial problems, including the 3D printing of overhanging components by having developed continuous glass fibre reinforcement technology and the instantaneous hardening of photopolymer/concrete composite ink triggered by UV-light exposure. Their enormous potential in on-site 3D printing should never be underestimated, and offers new perspectives of seeing fibre reinforced concrete and rapid hardening 3D printing inks.
Moreover, Shanghai saw the emergence of an on-site 3D printed library in the Baoshan District, designed by Prof Xu’s group at Tsinghua University. It has only one storey, while the steel reinforcement was replaced by short/chopped fibre that is embedded in the concrete matrix. The way of eliminating the manual installation of steel reinforcement to streamline the 3D printing process is of great interest both in academia and in industry.
To summarise, currently although building structures 3D printing has been implemented in few commercial buildings globally, the printed results either have only one storey or they are off-site 3D printed (pre-fab). To fully achieve the potential of 3D printing in the construction sector and make it ubiquitous, construction-scale on-site 3D printing of multi-storey buildings is a necessity. This is also the core of attention from academia. Scientists and engineers are undertaking various pieces of research to enhance the strength of 3D printing building materials and to overcome the limitations of on-site 3D printing construction. It is worth noting that for large-scale on-site 3D printing, a 3D printer with multiple nozzles or multiple printheads working collaboratively is what the future desires to further accelerate the construction process.