Mineral wool is one of the most commonly used insulation materials in building construction. However, because it is very light and voluminous, it takes up a huge amount of landfill volume and is not very stable. In Austria, the landfilling of mineral wool will be banned from 2026.
PORR has developed and patented an innovative processing plant specifically for mineral wool waste. The material is crushed and mixed with aggregates in a way that manages to reduce the volume by up to 80%. This allows the material to be landfilled or otherwise recycled. The plant is sealed and the air is completely extracted and filtered so that no fibre emissions escape. Estimates suggest around 24,000 tonnes per year of mineral wool waste are generated in Austria.
“In the construction industry, and especially at PORR, our goal is always to achieve a circular economy. That’s why, after this successful step, we are also exploring recycling and recovery options for mineral wool”, says Zeljko Vocinkic, Managing Director of PORR Bau GmbH and recycling expert at PORR. “However, as with other construction waste like polystyrene, we have the problem that mineral wool is not a pure waste product but naturally contains contaminants. So a solution has to be found for that”.
Getting the framework in place
PORR recycles 2.2 million tonnes of construction waste every year, both at recycling sites such as Himberg and on its own construction sites. Of this total, 1.7 million tonnes are used instead of primary raw materials on PORR’s own construction sites and facilities. One especially successful area is the recycling of concrete, for example, which is processed into recycled concrete, and the recycling of bricks, which become a plant-friendly roof substrate used for green roofs. Asphalt also becomes recycled asphalt.
“We are increasing our recycling rates in other areas as well. For example, we are involved in a research project on recycling polystyrene and a project for recycling gypsum – two areas that are both still extremely underexplored in Austria”, says Vocinkic. “There is still enormous room for improvement here in terms of R&D”.
Overall, the expert sees the goal of a circular economy as a critical issue. A lot of things are possible, but they must also be legally permitted and economically sustainable. “One example is recycled concrete. There are regulations that say concrete of certain quality classes may only contain 10-15% recycled concrete. If these quality classes are required in tenders, that limits our options. The situation is completely different in the Netherlands, for example. If we want to increase the recycling rates, then the framework conditions also need to change”.