Building new buildings from old ones

Holcim launched its formal take on construction and demolition waste (CDW) this week with the unveiling of its ECOCycle technology platform at the BAU architecture fair in Munich. This amounts to managing the distribution, processing, grinding and recycling of CDW back into new building material products. It claims that its concrete, cement and aggregate products can contain 10 – 100% of CDW with no drop in performance.

It is hard to gauge whether this is marketing for existing operations or the start of something new. Yet, in its 2022 Sustainability Report, Holcim said that it recycled 6.8Mt of CDW back into building products and that it is on track to meet its target of 10Mt by 2025. This target was neatly put into words as wanting “to build more new buildings from old ones.” Ahead of the announcement of the launch of ECOCycle, it added that it was going to roll out its Susteno product around Europe. This product, made from 20% CDW, was originally released in Switzerland in the late 2010s. Notably, recent acquisitions by Holcim that connect to its growing focus on CDW include Poland-based Ol-Trans in July 2022, UK-based Wiltshire Heavy Building Materials in October 2022 and UK-based Sivyer Logistics in April 2023.

As covered by Global Cement Weekly in February 2023, Holcim is not the only heavy building materials company pivoting to CDW. The European Union (EU) set a 70% recovery target for it in 2020 and various cement company sustainability reports have described the region as being receptive to moves into this sector. Cemex set up a global waste management subsidiary called Regenera at the end of January 2023. This division covers both alternative fuels, CDW and industrial by-products, so it is more general than Holcim’s current effort, but it shows intent in the same direction. Cemex previously set a target of recycling 14Mt/yr CDW by 2030.

Heidelberg Materials has been working on developing recycled concrete paste and its ReConcrete-360° concrete recycling process. As of its last sustainability report, this process had been tested at the pilot scale and is now being developed and scaled for industrial application. In addition to acquiring UK-based Mick George Group in December 2022 Heidelberg Materials has also purchased Germany-based RWG Holding in January 2023 and Germany-based SER Group in February 2023. All three companies operate in the CDW sector.

The other notable contribution that Heidelberg Materials has been making is as a partner of the ‘Circular City – Building Material Registry for the City of Heidelberg’ project. When Heidelberg Materials announced its involvement in the initiative in mid-2022 it said it was the first city in Europe to apply the principles of urban mining. The goal of the project is to take an inventory of the city’s buildings and then compile it in a digital material registry. The basis for the registry is the Urban Mining Screener developed by EPEA (Environmental Protection Encouragement Agency). This programme can estimate the composition of buildings based on building data such as location, year of construction, building volume or building type. Circular economy supply chains can then act accordingly when a building is retrofitted, demolished or deconstructed. So, for example, at the start of the project it worked out that a former US Army housing estate conversion site was calculated to contain approximately 466,000t of material, with about half in the form of concrete, a fifth in the form of bricks and 5% as metal.

That last example compares to a European Commission estimate that, as a whole, Europe generates around 450 – 500Mt/yr of CDW. A third of this is concrete. As with alternative fuels and slag previously, this may be money going into the ground. Recycling building materials is not new but any significant increase in reusing CDW that can reduce the clinker factor of cement (and the cement factor of concrete) offers a potentially cheaper route to building materials decarbonisation than carbon capture and utilisation/storage at current costs. Hence the continued interest.