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Ten questions to help you choose the right waterproofing system for your tanked structure

Shotcrete – Fall 2004

When it comes to preventing water damage and preserving the integrity of concrete structures, waterprooing is essential. In the case of concrete tanks, however, effective, reliable waterproofing is especially critical.

Concrete tanks play a vital role in many communities. They function as drinking water containers, wastewater treatment plants, and water storage reservoirs. Not only is a leak in a facility like this expensive and time-consuming to repair, it can be inconvenient and even dangerous to the community.

A town’s water supply can be compromised by waterborne chemicals migrating into drinking water. In drought-affected areas, water lost through leakage from a reservoir can be costly. And wastewater leaking from treatment plants can contaminate the ground or environment.

Effective waterprooing is especially important in underground or partially buried concrete tanks because below-grade cracks and leaks may be more difficult to detect and more expensive and time-consuming to repair.

Recognizing that the vast majority of concrete will eventually crack (and leak)due to shrinkage, settling, seismic activity, and other factors, how do you protect your concrete tanked structure and keep water in and contaminants out? The best solution is to plan ahead and invest in a high quality, long-lasting concrete waterprooing system.

There are a number of concrete waterprooing systems available on the market today suitable for use with shotcrete:

• Rubberized or polyurethane membranes or barriers that are applied to the positive (exterior) side of the structure before steel reinforcements are positioned and shotcrete is applied;
• Sodium bentonite, a clay material applied in panels to the positive side of the structure. Bentonite works by absorbing water and swelling to fill the cracks and voids in concrete. Upon reaching its maximum volume, the product stays in the cracks and voids to seal against future water intrusion ;and
• Integral crystalline waterproofing (ICW) systems, which create a chemical reaction within concrete that causes crystals to form, filling the spaces between concrete particles and permanently blocking water. Some ICW systems react with the presence of water to grow additional crystals to self-seal cracks that develop. ICW can be applied as an admixture into the shotcrete mixture or applied in a cementitious form to the positive or negative side of an existing concrete structure.

Read more about:

• 10 things to consider when choosing a waterproofing system.
• Case Study: Oregon’s Talent Irrigation District Tackles Fishy Waterproofing Challenge