Waterproofing of pressurized purification tanks in Vicenza

Purification tanks are often constructed following good concrete practices, using commonly available materials, such as fiber cement spacers and plastic pipes. However, the conditions to which the materials are subjected on site are often more “stressful” than those specified by suppliers as operating conditions. As a result, construction defects, such as pressurized water leaks, can occur.

In our case, epoxy resins were applied to seal the holes. However, due to a possible incorrect mixing or incorrect curing of the components, <strong>leaks occurred along the main stress lines, with water leaking from the holes in the fiber cement spacers</strong>. Another issue involved the gravel nests present, which caused leaks in the structure and required corrective action.

The solution adopted for waterproofing pressurized sewage treatment tanks, using PROIND S.r.l. products, specifically SIRIOSEAL, involved the use of materials that could be applied with common construction site tools (trowel, paintbrush, and float). These materials, in addition to being non-hazardous to health, guarantee high performance under stress and operating conditions. SIRIOSEAL proved particularly effective, being an osmotic cementitious mixture capable of creating a thin coating resistant to water penetration, even under pressure, both positive and negative.

We decided not to completely drill the structure (thus maintaining the cap and seal inside the tank), and by evaluating the depths, we:

1. Drilled a hole near the pipe, removing a portion of the fiber cement spacer for a length of approximately 80-100 mm, “exposing” the cement portion;

2. A bentonite paste such as BENTOPASTA was inserted inside the existing spacer. The paste, with a defined diameter, was given (being malleable) a length of approximately 50 mm and inserted into the hole, determining its position with a simple rod;

3. After thoroughly wetting the hole and the work area, BENTOPASTA mortar was first applied inside the hole to compensate for any future water pressure, and subsequently;

4. BENTOPASTA mortar was applied to the external surface, both as a “crystallizing bandage” for the previous mortar and to restore the repaired surface to an aesthetically pleasing appearance without altering the color of the surfaces.