Water pump repair at PAP Lisina, HE Vrla

Overview

The pump manhole at HE Vrla, managed by HE Đerdap in Kladovo, Serbia, was experiencing severe water penetration issues that jeopardized the structural safety of the unit. The reinforced concrete walls, constructed as a double sandwich with a thickness of 2x120.0 cm and metal plates welded for waterproofing, showed significant flaws such as cracks, segregations, and visible water penetration, particularly in the areas where the diameter of the manhole changed.

Problem Statement

The water infiltration was especially problematic as it posed risks to the substation, high-voltage cables, and electronic systems. Despite earlier attempts to rectify the problem using traditional methods like PU resin injections and coatings, the issues persisted. These previous methods were inefficient due to many weak spots and inaccessibility to the surface of the vault.

Solution: Euras Gel Type B High-Pressure Injection

After evaluating different options, the project team decided to employ Euras Gel Type B. This innovative material is designed to operate on hydraulic principles, allowing for high-pressure injections of up to 200 bar. Euras Gel Type B was carefully injected into the existing water courses in the metal insulation panels, using the water as a vector to distribute the gel material throughout the troubled areas.

Key Features of Euras Gel Type B:

1. High pH > 8.8: Passivated both the reinforcing steel and metal insulation, thereby enhancing structural integrity.
2. High-pressure application: Enabled penetration into inaccessible areas and weak points.
3. Water course alignment: Used existing water pathways as vectors for gel placement.

Implementation

Over 35,000 kg of Euras Gel Type B was incorporated into the structure. The high-pressure regime facilitated the gel's penetration deep into the existing cracks and gaps, effectively blocking the water courses and halting water infiltration. The gel also filled cavities within the concrete that were previously filled with aggressive water, indicating that even seemingly sound concrete had hidden vulnerabilities.

Results and Conclusion

1. Water Penetration Halted: Following the application of Euras Gel Type B, no further water infiltration was observed, significantly improving the safety conditions of the manhole.
2. Structural Integrity: The gel's high pH served to passivate the metal components, further enhancing the structure's long-term durability.
3. Cost-Efficiency: Although the Euras Gel Type B material and application were a significant investment, the effective results negated the need for future remedial measures, thereby proving to be cost-efficient in the long run.

This case study demonstrates the effectiveness of Euras Gel Type B in tackling complex water penetration issues in reinforced concrete structures, particularly where traditional methods had failed. The project serves as a valuable example for similar issues in hydraulic structures, showcasing the benefits of utilizing advanced materials and application techniques.