International - Special edition on Foundation Decarbonization and Reuse

With increasing emphasis on sustainability, the reuse of existing foundations presents a viable alternative to a completely new foundation whenever a new building is constructed at the site. After all, the economic lifetime of buildings is often shorter than the technical lifetime, leaving structurally sound foundations underutilized. However, reusing foundations presents challenges, primarily related to uncertainties in their bearing capacity and remaining service life.

The paper advocates for a shift in the design process: instead of assessing whether an existing foundation meets a predetermined structural layout, designers should first evaluate the foundation's potential and then tailor the superstructure accordingly. By aligning the new with the existing foundation, greater reuse opportunities emerge, ultimately promoting a circular economy in the construction industry.

Funderingstechnieken Verstraeten BV (Fundex) was founded in 1953 and has been an expert in the field of international foundation projects for many years. You can only achieve that status if you continuously innovate and Fundex is unique in that too.

Underground car parks (UCPs) are one option to increase the number of parking spaces in densely urban areas. Many UCPs are built with permanent steel sheet pile (SSP) retaining walls, but this is rarely the case in Germany. This case study compares four retaining wall alternatives for the execution of a typical two level UCP in the Berlin area. It shows that a permanent SSP wall is more cost-effective than a secant pile wall and a diaphragm wall, and a Life Cycle Assessment shows that the permanent SSP wall has also a lower carbon footprint (difference ≥ 120 %).

The Port of Rotterdam Authority aims to develop sustainable and future-proof port infrastructure. They aim to reduce CO₂ emissions of new port infrastructure by 50% before 2030, with the ultimate goal of achieving a net-zero carbon footprint by 2050. A critical factor in meeting these ambitious targets lies in the efficient use of both new and existing materials. However, accurately determining the capacity of port infrastructure poses a challenge, as these structures have demonstrated excellent performance without any observed failures. To better understand the reserve capacity of such infrastructure, full-scale field tests were conducted on flexible dolphins, foundation piles, and anchor piles.

This paper highlights the technical, commercial, and environmental outcomes of recent pile load tests carried out in the Port of Rotterdam. The findings reveal significant reductions in CO₂ emissions related to the manufacturing and installation of foundations, alongside minimized installation risks. Additionally, achieving higher reliability with reduced material usage has been made possible. Despite the expenses associated with full-scale testing, this study underscores the importance of verifying the actual capacity of foundation piles to enhance the sustainability of port infrastructure.

Next year the third edition of the International Conference on Foundation Decarbonization and Reuse (www.foundationreuse.com) will be held. During this conference, which will again be hosted by DFI Europe and the Geotechnical Section of the Royal Dutch Society of Engineers, various approaches to reduce the carbon footprint of a foundation will be covered. One option is obviously the continued use of an existing foundation when the old superstructure is replaced by a new one. This may require some out of the box thinking, e.g. how to supplement the existing foundation with new foundation elements or how to design the load-bearing structure of the new superstructure to match the existing foundation lay-out. But there are many other ways to reduce the carbon footprint, which will also more than likely reduce the cost of that foundation.

Next year the International Conference on Foundation Decarbonization and Reuse will be organized in March 2026, and it will feature a new event: a workshop on software tools to help the user to minimize the carbon footprint of foundations and to assess the options to reuse existing foundations. This article can obviously not predict the workshop's outcome, but it can highlight some key requirements to make software a useful tool in that endeavor.

To assist with decarbonization, the key requirement is straightforward: the software should be able to define the foundation with the smallest carbon footprint.. For reuse, however, defining the requirements is not as simple. Obviously, it should recalculate the bearing capacity of the foundation as designed. But should it also generate options to supplement those existing foundations if that bearing capacity is inadequate? Or should it merely detail user-defined options? These questions will be examined in this article.