Cementos Molins has been celebrating the first anniversary this week of its alternative raw materials unit at its Sant Vicenç dels Horts plant near Barcelona. It has processed 75,000t of waste since September 2022 when the site started up. More is yet to come as the unit has a production capacity of up to 200,000t/yr. The facility receives waste in coarse, granular, powder and sludge formats. Waste from concrete plants is crushed and screened to produce recycled aggregate. Industrial and construction waste is dosed and homogenised to produce alternative raw materials for cement production.

Global Cement Weekly has covered construction and demolition waste (CDW) a couple of times already so far in 2023. A number of cement producers are investing in the sector - including Holcim, Heidelberg Materials, CRH, Cemex – by developing technology, buying up other companies, setting up internal CDW divisions and so on. Holcim and Heidelberg Materials have been the more obviously active participants over the past six months based on media coverage. In September 2023 Holcim France commissioned the Saint-Laurent-de-Mûre alternative raw materials plant and Holcim Group invested in Neustark, a company promoting technology to sequester CO₂ in CDW. In August 2023 Lafarge Canada also completed the first stage of a pilot project to use CDW in cement production at its St. Constant plant in Quebec. Heidelberg Materials meanwhile announced in October 2023 that a forthcoming upgrade to its Górażdże cement plant in Poland would include a new CDW recycling unit and in September 2023 it launched a CDW division for its subsidiary Hanson UK.

Previously we have described how the European Union (EU) has set recovery targets for CDW. However, McKinsey & Company published research in March 2023 setting out the economic case for cement and concrete companies looking at CDW. It estimated that “an increased adoption of circular technologies could be linked to the emergence of new financial net-value pools worth up to roughly Euro110bn by 2050.” It is not a certainty and there is risk involved, but adopting circular practices is one way to reduce this risk. It then went on to predict that recirculating materials and minerals could generate nearly Euro80bn/yr in earnings before interest, taxation, depreciation and amortisation (EBITDA) for the cement and concrete sectors by 2050. The biggest portion of this could come from using CDW in various ways such as a clinker replacement or as an aggregate in concrete production, or the use of unhydrated cement ‘fines.’ Capturing and using CO₂ and increasing alternative fuels (AF) substitution rates would have a financial impact but not to the same scale.

Graph 1: CO₂ abatement cost via circular technologies for cement and concrete sectors. Source: McKinsey & Company.

Graph 1 above puts all of the McKinsey circular technology suggestions in one place with the prediction that all of these methods could reduce CO₂ emissions from cement and concrete production by 80% in 2050 based on an estimated demand of 4Bnt/yr. The first main point they made was that technologies using CO₂, such as curing ready-mix or precast concrete, can create positive economic value at carbon prices of approximately Euro80/t of CO₂. Readers should note that the EU emissions Trading Scheme CO₂ price has generally been above Euro80t/yr since the start of 2022. The second point to note is that using CDW could potentially save money by offering CO₂ abatement at a negative cost through avoiding landfill gate fees and reducing the amount of raw materials required. This is dependent though on government regulation on CO₂ prices, landfill costs and so on.

Cement producers have been clearly aware of the potential of CDW for a while now, based on the actions described above and elsewhere, and they are jockeying for advantage. These companies are familiar with the economic rationale for AF and secondary cementitious materials (SCM) in different countries and locations. CDW usage is similar but with, in McKinsey’s view, existing CO₂ prices, landfill costs, and regulatory frameworks all playing a part in the calculations. Graph 1 is a prediction but it is also another way of showing the path of least resistance to decarbonisation. It is cheaper to start with AF, SCMs and CDW rather than barrelling straight into carbon capture. The beauty here is that cement and concrete sold, say, 50 years ago is now heading back to the producers in the form of CDW and it still has value.