Circular economy

The Fass-Salzerei building in Rostock’s fishing port dates from the 1950s. The hall-type building has a reinforced concrete frame and brickwork structures at either end. It has a floor area of 5040 m² and a volume of 42,000³, and it is estimated to have been constructed using 11,500 tonnes of mineral materials. Demolition work commenced in early 2022 to make way for a new building, with the old structure being dismantled in a controlled and selective manner to enable as much as possible of the materials to be recycled. The work is complicated by several factors.

The pollutant levels of the existing building
First and foremost is the challenge posed by the widespread contamination with construction material pollutants, which are to be found throughout the building structure, in floors, walls, ceilings and roofs, and in the building’s equipment and fittings. The range of pollutants includes various types of asbestos contamination, substantial quantities of carcinogenic mineral wool, and large areas of asphaltic roofing felt. There are also numerous composite materials that would require an unreasonable amount of effort and expense to separate and that are contaminated with pollutants to some extent. Unfavourable static design conditions make material separation even more difficult. And even the uncontaminated demolition waste includes materials such as aerated concrete and sand-lime bricks which have very limited recycling potential. Dealing with the contamination has major implications in terms of personnel, time and cost. It is likely to take up half of the total demolition time, considering the extensive occupational safety measures and labour-intensive work processes that it requires. The removal of pollutants is associated with significant physical strain for the people carrying out the work. And of the total demolition costs, which are expected to come to tens of millions of euros, 80 to 85 percent are likely to be attributable to the removal and disposal of the pollutants. The planning of work to demolish such a building and dispose of the contamination can only aim at damage limitation. Unfortunately, the potential for unproblematic recycling of the demolition materials is very low.

Conclusion
This project example shows clearly how important it is to address the topic of “circular construction” early in the planning and design process for building construction and building renovation projects. The following considerations are relevant, among others:

• Refraining from using pollutant-containing materials and from constructing on top of existing contamination
• Using materials that can be easily reused, reclaimed or recycled with high quality
• Not using composite materials, or using only composite materials whose constituent materials can be readily separated
• Designing structures to be readily dismantlable, also considering static design implications

Only by considering all such aspects can we steadily progress towards the goal of a circular economy.