Seminar "Ressource Efficiency in Foundation Engineering"

In recent years, resource efficiency has become increasingly important in the construction industry as well. In this context, the foundation engineering occupies a special position: Soil and stones make up about 60% of mineral construction waste in Germany. Although most of the landfill can be recovered, almost 18 million tonnes of waste accumulate each year and are disposed of in landfills. Particularly costly are residues that have a flowable consistency, resulting for example in the diaphragm wall excavation due to the mixing of the soil with supporting liquid or jet process from the so-called return flow. In addition to the aspect of environmental protection, therefore, economic aspects increasingly play a role when it comes to avoidance. However, this requires not only coordinated construction processes and concepts, but also other technical innovations in the areas of building materials and process engineering.

Contents of the seminar:
• Current challenges to building owners,
• Soil conservation on site,
• Interfaces in soil management,
• Utilization of the return flow in the jet-blasting process,
• Recycling of used bentonite suspensions,
• Landfill capacity of the future. 

Particular attention was paid to highlighting the different perspectives of builders, planners and contractors. Thus, all six contributions were followed by extensive roundtables in which all participants were actively involved in the technical discussions.
As expected, many of the participants in the event broke new ground with the addressed topic. In particular, the complexity of the processes related to the management of soil excavation - which has to be recycled and not landfilled - is often underestimated.
Remedy is only possible through a better understanding of the views of all involved. For example, not all environmentally relevant soil properties can be assigned to the subsoil risk as usual, which is the sole responsibility of the building owner.
After all, the construction company has far-reaching influence on how to deal with the excavation or the precious resource soil. This already applies to on-site treatment where unnecessary contamination and compaction are to be prevented. So far, however, there has been no economic incentive to push ahead with planning in this area too.
However, innovations can not only be expected in planning and soil management, but also in process engineering. A promising approach is, for example, a novel online measuring system with which the cement content in the so-called return flow in the jet-blasting process can be determined within a few minutes. This makes it possible to reuse the cement suspension with a sufficiently high proportion of cement and to prevent "precautionary disposal". Another example presented is the so-called electro-coagulation of bentonite suspensions, with which a separation of clay particles and water with moderate energy input and without chemicals is possible.