3D printed cement foam could reduce carbon emission

The 3D-printed FoamWork elements are arranged inside a timber perimeter mould

The 3D-printed FoamWork elements are arranged inside a timber perimeter mould

AM Chronicle Editor

 Researchers at ETH Zurich employed 3D-printed formwork pieces composed of recyclable mineral  cement foam to build a pre-cast concrete slab that is lighter and more insulated while using 70% less material, according to the researchers.

ETH Zurich develops formwork from 3D-printed foam to slash concrete use in buildings

The FoamWork technology involves filling a typical rectangular mould with 24 mineral formwork parts of various shapes and sizes before casting concrete over them and allowing it to cure, resulting in hollow cells throughout the panel. The resulting internal shape was optimised to reinforce the slab along its primary stress lines, resulting in the required strength while dramatically lowering the amount of concrete required to construct it. If implemented on a large scale, architect Patrick Bedarf believes it could assist to reduce the carbon footprint of building, particularly cement, which is the world’s largest single emitter of CO2. With FoamWork, emissions from material use in the concrete slab would be decreased. Lowering the bulk would also have a secondary influence on the dimensioning of the overall load-bearing structure, as well as reducing shipping and handling efforts on building sites.

Ultra high-performance fibre-reinforced concrete is poured around the formwork elements

The formwork pieces are 3D printed by an autonomous robotic arm utilising mineral foam, which is traditionally generated by foaming cement and is increasingly employed as an insulating material in construction due to its high porosity. To minimise the emissions associated with cement manufacture, the FoamWork system use a substitute developed by the Swiss start-up FenX that is formed of fly ash, a waste product from coal-fired power plants. According to the business, this helps to reduce the carbon footprint of the foam, especially when considering the emissions associated with coal combustion.

The formwork can be left in place or removed, recycled and reprinted

The final FoamWork of cement foam elements can either be left in place to improve the insulation of the precast concrete slab or recycled and reprinted to create new formwork. Considering that no offcuts are created in the additive manufacturing process, this means the entire system has the potential to be zero-waste.

 

The system was 3D-printed using an autonomous robotic arm

Hollow plastic forms can be used to decrease concrete in big standardised slabs, while sophisticated formwork for concrete is manually made in lumber or CNC-cut from dense plastic foams for smaller non-standardized applications. Both methods are time-consuming and waste a lot of material due to chipping and offcuts.

The internal geometry of the concrete panel (cement foam) was optimised for its specific shape, inspired by the way Italian architect Pier Luigi Nervi built ribbed floor slabs in the 1940s along their main stress lines. The shape and structure of the inside cells, on the other hand, may be customised to create a variety of concrete building elements ranging from walls to whole roofs.

The FoamWork provides additional insulation through its porosity

In an effort to reduce its massive carbon footprint, the Global Cement and Concrete Association recently pledged to achieve net-zero emissions by 2050. To do this, the industry is striving to develop alternatives for clinker, the most carbon-intensive component of cement, as well as using carbon capture technology to eliminate emissions generated during the clinker manufacturing process. At the moment, it entails burning calcium carbonate at high temperatures to separate the calcium required to make cement from the carbon, which is discharged into the environment. Until such technologies are widely accepted, the simplest method for architects to reduce the embodied carbon footprint of their buildings from materials and construction is to utilise high-carbon materials like concrete and steel more sparingly and efficiently. Currently, a large number of buildings in the UK are overdesigned according to Cambridge University engineering professor Julian Allwood.

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