Bonn-Beuel wastewater treatment plant, DE

Sewage plant Bonn-Beuel, Germany: Highly efficient special solution for low strength concrete substrates

The Bonn-Beuel municipal sewage treatment plant is located on the right bank of the river Rhine in Bonn's Siegaue, Germany. The Federal City of Bonn, as the investor and operator of the plant, had the existing structures of the plant refurbished in individual construction phases - the sand trap, the channel behind the sand trap, and the access road and its retaining wall around storm water overflow basin 3.

The construction work was carried out while the sewage treatment plant was in operation. Quick and convincing solutions were the key to the smooth and rapid realisation. The applied system solutions were specifically tailored according to the results of the analysis of the current state situation and to the expertise assessment by the planner. The tender from the investor required repair products and systems made by one manufacturer. In this way, the compatibility of the building materials in the system and thus the prerequisite for the warranty was ensured.

The investor and the specialised planner for concrete repair, IBE engineers from Hennef, Germany, relied on StoCretec products and systems tailored to concrete repair and concrete protection, as well as in our many years of experience and our specialist know-how. The decisive factor in selecting the appropriate concrete replacement system was compliance with the compatibility criteria: mechanical, thermal and hygric parameters had to be precisely tuned in the repair solution. In order to guarantee the durability of repair measures, special requirements had to be observed.

The repair of the sand trap at the Bonn-Beuel sewage treatment plant was a particular challenge. The planner's condition analysis had shown that the substrate was to be classified as low-modulus concrete of existing concrete class A3*. Due to the long-term strong impact of municipal wastewater and its chemical attacks of exposure classes XWW1 to XWW3, the concrete substrate was significantly affected.

The engineers of company IBE-Ingenieure, in collaboration with the experienced applicator Massenberg from Cologne, Germany, decided to refurbish the concrete with StoCrete TS 136, a polymer-modified dry-sprayed mortar. The special concrete repair product (SRC-A3) is ideal for restoring concrete of substrates with low strength and low modulus of elasticity, of the existing concrete class A3*. It combines the mechanical properties adapted to existing concrete with the high requirements for durability. The 20 GPa modulus of elasticity concrete repair product ensures a stable bond with the sub-surface and ensures the long-term functionality of the sand trap.

On the restored areas of the sand trap, the concrete repair specialists additionally applied a protective coating made of StoPox 452 EP, the epoxy resin primer specifically for damp substrates, and the StoPox WHG Deck 105 top coat as the main surface protection layer of the StoFloor Industry Elastic WHG Deck 105. The coating is highly chemically resistant and crackbridging. It is also suitable for surfaces subject to mechanical stress. This prevents any cracks still present in the substrate of the existing concrete from breaking through and causing further damage from penetrating water or substances dissolved in the wastewater.

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