Construction and demolition waste accounts for more than one-third of all waste generated in Europe, and most of the components of construction and demolition leftovers have value. Reducing, reusing and recycling waste and by-products from production processes is therefore a major challenge for our industry.

At Xella, we have taken the first steps to develop the circularity of our materials. We have a great opportunity because our main products, autoclaved aerated concrete (AAC) and calcium-silicate units (CSU), are almost completely recyclable. Our first step towards a circular economy is to stop sending any AAC or CSU residues or production leftovers to landfill by 2030. This has made us rethink and refocus our efforts to create more innovative ways to find alternative uses for these materials and to test new recipes for our products.

These are the pillars on which the circularity of our materials is developed:

• Reducing raw material consumption
  Our St. Savin plant in France successfully pioneered the use of crushed AAC leftovers to replace mineral resources in production. This reduced sand consumption by 10% and saved 159 tons of CO2e in 2023. We will extend this process to other plants in 2024.

• Reducing material needed on construction sites
  We use digital tools for precise planning and just-in-time deliveries to reduce leftovers on construction site. Our digital teams are having a significant impact. Working on 1,334 projects across Europe in 2023, they used this methodology and innovative approach to reduce the amount of cut-off and leftover material, saving 9,000 m3 - for example, in the construction of the Wings building in Romania.

Sourcing AAC from construction sites: Our "big bag" collection of segregated AAC offcuts has been a major factor in bringing residuals back to us rather than sending them to landfill. They are available in several countries, such as Germany, where more than 1,360 tons of AAC off-cuts were collected in 2023.

• Reuse AAC leftovers in our recipes
  In addition to utilizing processed leftovers from our own plants, we have collaborated with recycling companies to develop promising solutions for accurately sorting recycled AAC from demolition waste, enabling its reintroduction into our production process. In 2023, Xella’s research department, the Xella Technologie- und Forschungsgesellschaft mbH (Xella T&F) conducted fundamental research revealing we can replace up to 25 percent of raw materials with crushed and milled AAC in the majority of our German plants.

• Reusing materials in new projects
  In a factory building in Almelo in the Netherlands, we were able to reuse panels directly on the construction site: as part of a major renovation project, 1,100 m2 of fireproof Hebel partition walls will be reused in the rebuilding of the factory, after careful inspection at the Xella plant. Read more about the project.

This has also worked perfectly in Puchheim, Germany: since the AAC from an old factory building was in very good condition, the material was sorted (to obtain unmixed material) and processed (crushed) by a demolition & recycling company and hereafter reintroduced into the production process of the new AAC panels used for construction. Read more about this pioneering project.
 

• Recycling
  Although regulations vary across Europe, we want to expand our partnerships to ensure a steady supply of construction and demolition waste material to increasingly replace the use of raw materials. While we are not involved in building demolitions, we are actively developing a strategic plan to acquire and repurpose demolition waste as part of our ongoing efforts to advance sustainable practices.

• Developing alternative uses
  Circularity has also opened up new opportunities for us: we have developed an application for converting AAC residues into granules and are gradually expanding alternative uses for these. Cat litter has been one of our most successful adaptations, but other uses include soil conditioners, wastewater filters, fertilizers and chemical binders.

Together with our project partner, the renowned Karlsruhe Institute of Technology (KIT), we have developed a process for the synthesis of low-temperature belite cement clinker (LT-BCC) from secondary AAC recovered from demolition waste. Read more at KIT.

These efforts towards delivering circular transition are only a few pieces of the puzzle in our sophisticated and well-thought-out ESG strategy. Learn more about it in our 2023 ESG Report