Anaerobic Digester Top Edge Repair

BACKGROUND

The challenge arose when the removal of the roof from the anaerobic digester exposed cracking and minor spalling along the top edge of the site-cast concrete structure. Additionally, during a detailed site survey, the tank lining was found to have deteriorated in certain areas, leading to concrete degradation caused by prolonged exposure to hydrogen sulphide.

OUR SOLUTION

The project was carried out in October, when achieving the ideal climatic conditions for conventional coatings was a challenge. To address this, Corroless Eastern carried out the works using Sikagard P770 primer and Sikagard M790, a highly damp-tolerant tank lining system. This polyurethane solution, known for its crack-bridging and chemical-resistant properties, is suitable for environments with no dew point or relative humidity restrictions, as long as the surface is free from water and condensation.

The initial surface preparation involved vacuum-controlled diamond grinding to remove the existing, failed tank lining and expose any defects in the concrete. This step ensured that the concrete surface was clean and ready for the new tank lining to bond effectively.

To repair cracks, diamond saws were used to express the concrete, followed by filling with a high-strength epoxy repair mortar to restore the integrity of the structure.

As part of standard quality assurance, the moisture content of the concrete and the climatic conditions were tested and recorded. This process confirmed that while the surfaces were dry, the moisture content was over 5%, and the surface temperature was not 3 degrees above the dew point. These conditions validated the decision to proceed with the proposed tank lining system.

Once the surfaces were adequately prepared, Sikagard P770 was applied as a primer, mixed with fine quartz where necessary to fill imperfections. The first coat of Sikagard M790 was then applied to a wet film thickness of 500 microns, with thickness readings taken throughout the application to ensure precise coating consistency.

           BENEFITS

Sikagard P770 and Sikagard M790 were used for their high damp tolerance, enabling the coating work to proceed even in challenging weather conditions with no dew point or humidity restrictions.

The polyurethane solution is crack-bridging and chemical-resistant, ensuring long-lasting protection in demanding environments..

Extensive testing of moisture content and climatic conditions validated the chosen coating system, confirming its suitability for the project's conditions and ensuring optimal performance.

Damp-Tolerant Coating System: Corroless Eastern used Sikagard P770 primer and Sikagard M790 for a highly effective, crack-bridging, and chemical-resistant tank lining, capable of withstanding challenging climatic conditions without dew point or humidity restrictions.

Precision and Quality Assurance: The project involved meticulous surface preparation using diamond grinding, crack repairs with epoxy mortar, and rigorous testing of moisture and climatic conditions to ensure optimal application of the tank lining for long-term durability.