Replacement of cement with waste: Embrace the circular economy with polymer technology
When approaching the process of recycling construction materials, there are a number of obstacles to achieving a comprehensive and effective result. First, careless destruction can make the process very complicated, as products with different recycling products are often mixed. In addition, not all materials can be efficiently recycled or processed, as many still require expensive or overly complex processes. But the construction industry, which has made a huge contribution to waste generation and greenhouse gas emissions, has also developed a number of new technologies to improve its practices. This is the case with the WOOL2LOOP project, which seeks to address one of the biggest challenges in applying a circular approach to construction and demolition waste.
One example of unexplored possibilities for roundness is mineral wool. These are fibrous materials formed by spinning or extracting minerals or molten rocks, such as slag and ceramics. They work as excellent heat and acoustic insulators, as they have extremely low density. For the same reason, they can become a problem in demolition, as they occupy a significant place in landfills; they are very light but very bulky. As mentioned in this article, “In Europe, around 2.5 million tonnes of mineral wool waste are generated each year during construction and demolition. At present, mineral wool waste is deposited almost entirely in landfills, resulting in annual costs of around € 250 million for the construction sector.
The WOOL2LOOP project aims to use mineral wool waste, after treatment, in products such as facade panels, acoustic sheets, paving slabs and even as units for 3D printers. For this purpose, a process has been developed that begins with the separation of mineral wool residues, their grinding and their use as products by alkaline activation (or geopolymerization), turning them into ceramic or concrete-like materials. Geopolymers are considered good alternatives to traditional Portland cement (OPC), mainly due to comparable mechanical properties while emitting some carbon dioxide. The great advantage is that several residues of existing industrial processes can be used for the production of geopolymers, such as fly ash or furnace slag, which makes the process ideal both from an environmental and economic point of view. To get an idea of the impact, approximately 5-10% of all man-made CO2 emissions are generated in cement production. Geopolymerization is becoming an increasingly accepted method for the production of low-carbon binders, other products and materials from various industrial by-products, one of which is mineral wool waste.
It is estimated that mineral wool geopolymer concrete produces approximately 80% less CO2 emissions than regular concrete and the final product is twice as hard as conventional high-strength concrete.
Among the various areas of the project, 3D printing is one of the most promising. Different possibilities for printing different geopolymer mixtures containing insulating materials extracted from construction sites are currently being tested. With appropriate mixing ratios and adaptation of printing technology, new geometries can be made that could not otherwise be made with traditional techniques.
WOOL2LOOP was developed by a consortium of 15 partners, with companies including Saint-Gobain Finland, NGOs and research institutions. As Anne Kaiser, Sustainability Manager at Saint-Gobain Finland, points out, “By turning mineral wool into a raw material for new products at the end of our lives, we become part of new industrial ecosystems and promote eco-innovation in the circular economy while reducing landfills. construction and demolition wastes’.
Learn more about the WOOL2LOOP project on the official website.