Fly ash for the dam construction site at Grimsel (Switzerland)

Image of a dam from above in Switzerland

Our fly ash is traveling to the high mountains: A 113-meter-high dam is currently being built for electricity generation at the Swiss Grimsel Pass.

The new, double-curved arch dam is intended to replace the existing Spitallamm dam, which, after 90 years of operation, urgently needs renovation and raising. The owner has decided to build a new dam directly in front of the existing one; the old dam will be preserved and later flooded.

Fly ash as a cement replacement with special properties

Fly ash acts as a binder in concrete - replacing the cement usually used for this purpose. This not only has a positive impact on the climate, but also noticeably improves the durability of the concrete:

Cement generates heat of hydration when concrete is poured, which can lead to temperature differences between the concrete core and the concrete surface. The more massive the structure, the greater the temperature difference during hardening - and the longer it takes for the concrete to cool down. This cooling process can cause cracks in the concrete. By adding fly ash, the heat of reaction is significantly reduced. This results in high-quality concrete with long-lasting durability - even in extreme weather conditions.

Strong network

The fly ash needed for construction is contributed by our subsidiary, Powerment - totaling approximately 13,000 tons from 2021 to summer 2024. "Our Swiss distribution partner, Presyn, delivers the fly ash to the construction site; the concrete is then mixed on-site using mobile plants," reports Jochen Pfitzner, Managing Director of Powerment.


We have been working closely together for over ten years. In addition to performance, trust and open direct communication between partners are key success factors.
Andreas Tettue
Managing Director at Presyn AG

Sophisticated logistics

The fly ash originates from the Rheinhafen-Dampfkraftwerk Karlsruhe and is transported to Switzerland by truck. A real challenge for all involved is the geographical location of the construction site at around 1,980 meters above sea level. Due to harsh weather conditions, concrete can only be poured from May to the end of October. However, fly ash as a byproduct of power plants is particularly available during the winter months - it becomes scarce in summer.

Ensuring the availability of fly ash counter-cyclically is a logistical challenge: "We have external storage capacities of several tens of thousands of tons and can thus store large quantities of fly ash in between," reports Jochen Pfitzner. In addition, the Grosskraftwerk Mannheim was planned as a second solution for emergencies. Furthermore, the truck journeys to Switzerland are meticulously planned to ensure precise deliveries. In case of delays, Presyn AG had a buffer storage facility planned beyond the border. The on-site storage range of the construction site is approximately one week, significantly more than industry standard.

Further information

Powerment specializes in the procurement of by-products from coal-fired power plants and their marketing to the construction industry: www.powerment.de

Presyn stands for high-quality products and services for concrete and mortar production: www.presyn.ch

The new construction is being carried out on behalf of Kraftwerke Oberhasli, who provide online information about the construction project: https://www.grimselstrom.ch/ausbauvorhaben/zukunft/ersatz-staumauer-spitallamm/

The construction of the dam is being undertaken by a consortium ARGE Grimsel (Frutiger AG, Implenia Schweiz AG, Ghelma AG Baubetriebe).

Picture: www.implenia.com