3D printing, also referred as additive manufacturing (AM), is a major element of the fourth industrial revolution and has the potential to transform the construction sector as a way of introducing robotization into construction.
3D printing is the process of creating an object by solidifying a raw material (e.g. plastic, metal, wood or concrete) under the control of a computer using Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) interfaces to guide the 3D printer nozzle.
3D printing minimises material waste, reduces the duration of the construction phase, and helps to minimise labour accidents. The usual process starts from a 3D digital model of the item created from CAD, Building information modelling (BIM), or 3D scanning sources.
The printer then follows the instructions processed through a CAM programme (G-code) to lay down, according to the defined parameters, the successive layers of printing medium (this can be a liquid, powder, or sheet material) which are joined or fused to create the item.
Multi-material 3D Printing can produce highly complex objects consisting of several materials and colours. Importantly, there are limitations since materials such as metal can be expensive to print, and in this case, the interest and cost-effectiveness can be found in printing a mould, and then that being used to create the item.
The C3PO project, receiving support from the European Regional Development Fund (ERDF), printed for the first time an entire building envelope in one piece in situ. Beneficiary Kamp C has completed the printing of a 2-storey house of 90m² using a fixed 3D concrete printer in 2020.
The innovation lay in the use of a prototype gantry printer, measuring approximately 10m x10m that worked in a similar way as conventional desk 3D printers. This video shows the printing of the envelope.
Traditional construction techniques remain necessary for the inclusion of elements such as the roof, the windows, and interior features. According to the project partners, the house is sturdier than brick-built homes and uses almost no formwork in its construction, saving an estimated 60% on materials, time, and budget.
This 3D-printed house was created for research purposes and to highlight the possibilities of 3D-printed architecture. There are no plans for anyone to live in it.
The combination of BIM, with automated robots and 3D printers could lead to a fully automated prefabrication process turning 2D drawings or 3D models into prefabricated and standardised construction components. An example is the prefabrication of concrete slabs.
A multi-disciplinary team from ETH Zurich University for Science and Technology is optimising 3D printing to reduce the volume of cement to only where it is structurally required.
The method for 3D-printing concrete these researchers have recently developed could reduce the amount of concrete used in construction projects by 50%. The innovation lies in the dynamic control of the setting speed of concrete that allows designers to create new forms.
More liquid material produces smoother, detailed pieces for casting, while a faster drying, rougher looking form of concrete is used for essential foundational pieces.
Looking at the materials used, currently most 3D printed construction projects use concrete. However, alternative materials that could be more sustainable and more energy efficient with a lower carbon footprint and less waste production are under investigation.
Bioplastic might be an appropriate alternative because it could lead to a lower environmental impact than concrete. Examples of 3D printed construction using bioplastics can be found on the canal-side site of Dus Architecture in Amsterdam.
The plastic used to create their canal house is over 50% bio-based (from linseed oil). This video shows how an enormous printer heats the material to produce streams of molten polymer and then layers them on top of each other to create the desired shape.
The machine can construct building elements that are up to 5m tall. Where an average building project has 25% material waste, the combination of bioplastics and 3D printing, reduces this to the bare minimum.
The team behind the house claims it is a waste-free, eco-friendly way to design and construct the cities of the future.
The Evo Constructor project looked into the commercial potential of a mobile system based on a robotic machinery technique that enables the automation of all processes necessary for the construction of buildings and other civil works.
Aware of the limitations of current 3D printing systems for construction, the project developed the so-called Evo Constructor mobile gantry robot.
The innovation that differentiates the Evo Constructor from any current alternative in the market is its unique cloned axis system, the economic and environmentally friendly characteristics and its self-climbing system, which translates into important savings in terms of cost and time.
The HINDCON project developed and demonstrated a hybrid machine regarding 3D printing technologies with concrete materials.
The project focused on the industrialization of the construction industry, delivering to this sector an innovative technology that reduces its environmental impact and at the same time reduces the economic costs.
The HINDCON project resulted in a number of innovations compared to existing additive manufacturing technologies using concrete in construction. The key innovation of the project lies in the development of a prototype ‘all-in-one’ hybrid 3D printing machine.
This resulted in the first 3D printer for large-scale precast pieces with a cable-driven parallel robot for positioning, allowing both additive manufacturing (AM) and subtractive manufacturing (SM), and the use of different cementitious materials, including fibre reinforced concrete.
The project also managed to translate data from BIM to G-code for the operation of the 3D printer.
A novel but still relevant project is the H2020 Scan4Reco project. The project developed an innovative solution for customised and cost-effective automatic digitisation and analysis of cultural heritage assets.
One of the main goals of the project was to create highly accurate digital surrogates of cultural heritage assets, providing a detailed insight of their surface and the volumetric structure, material composition and structure of underlying materials, enabling rendering either via visualization techniques or via multi-material 3D printing.
Although the building sector was not the main target of the project, some outputs could be relevant for the renovation of historical buildings, such as the publicly available material database containing extensive measurements on reference materials that were artificially aged.
This database integrates all Scan4Reco technologies for acquisition, diagnosis and simulation, to the point that (depending on the identified degradations of the Cultural Heritage asset) it provides comprehensive conservation approaches.
The project results were presented at the 4th Historic Mortars Conference, held in 2016 in Greece.
The H2020 project, PassivDom, carried out a feasibility study for the commercialisation of the so-called PassivDom, a 3D printed a ready-to-use mobile, self-sustainable off-the-grid house powered solely by solar energy with a self-learning integrated smart IoT (Internet of Things) system, with all the necessary equipment and furniture to start living in it from day one.
The PV cells integrated in the roof generate electricity for all the needs of the inhabitants. A standalone water supply system with filtration and a sewage system make the house completely autonomous, with zero bills on electricity, heating, and water, while having no negative impacts on the environment.
This project has enabled PassivDom Ukraine LLC to ensure its successful commercialisation through the PassivDom Corp having found a manufacturing partner and key suppliers in USA.
Considerable research went into the development of 3D printing technology for construction components. However, the development of insulation for 3D printed walls received little attention until now.
The H2020 Ultra-LightCon-3D project that started in July 2019 aims to provide an solution to that challenge with the development of an ultra-lightweight concrete (ULWC) with ultra-high insulating properties for 3D-printed walls.
The project focuses on two types of concrete mixtures: ultra-lightweight aggregate concrete mixtures and foamed concrete mixtures. A multi-scale tool will enable the production of advanced 3D printed wall systems.
The project hopes to prove that the use of 3D printing technology requiring no formwork will allow for reducing the costs of construction compared to conventional concrete construction projects that require considerable efforts related to formwork.
To sum up, 3D printing and digital fabrication are fields where innovations look promising, and important evolutions are expected. The Commission Communication titled ‘A New Industrial Strategy for Europe’ published in March 2020 highlights the importance of 3D printing for the European industry.