Resisting Pressure with Penetron: Enabling a High-Performance Solution for New York’s OCWA 4-Acre Reservoir

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Increased security requirements for infrastructure and unrelenting price pressure on construction projects are big financial and political issues for municipal governments. The recent completion of an upgrade to the Onondaga County Water Authority (NY) reservoir system illustrates how the use of an effective concrete waterproofing agent can help meet stringent performance and cost requirements.

In May of 2010, the Onondaga County Water Authority (OCWA) authorized construction of a 32 million gallon water holding tank to serve more than 340,000 residential, commercial, and industrial customers in four counties in Central New York. The project, located in Manlius, NY and completed at the end of 2011, was part of an upgrade of existing open-air in-ground reservoirs, converting these into enclosed and protected concrete tanks to comply with anti-terrorism legislation to make infrastructure secure against sabotage. At present, the OWCA provides approximately 40 million gallons of treated potable drinking water.

Huge – and now waterproof
“The previous open-air reservoir had become a security risk and needed to be converted into a secure facility,” adds Jeremy Swartzfager, Sales Representative for Penetron. “What the OCWA built was huge: it’s the largest reservoir on the East Coast!”

The water tank construction – spread over more than four acres – consisted of cast-in-place slabs, walls, and columns. A crystalline waterproofing agent (Penetron Admix®) was used for a project of this scale. Penetron Admix is a blend of Portland cement, very fine treated silica, and various active, proprietary chemicals. Mixed with fresh concrete, it triggers a catalytic reaction that forms a non-soluble crystalline structure throughout the pores and capillary tracts of the concrete, which is now tightly sealed from water or liquid penetration.

“The Penetron Admix was chosen because it met all requirements of the OCWA Eastern Reservoir construction,” adds Chris Chen, Director of North American Sales and Marketing at Penetron. “It enables the concrete to resist extreme hydrostatic pressure from either the positive or negative surface of the concrete slab and can seal hairline cracks up to 1/64” (0.4mm) wide.”

Further technical aspects underline the advantages of the Penetron Admix agent:

  •     Saves man-hours: simply mix with water, the thin slurry is then poured into the ready-mix concrete in the truck, no need for membranes and coatings
  •     Non-toxic: it is NSF 61 certified and suitable for potable water applications
  •     Helps avoid vapour pressure: renders the concrete highly resistant to aggressive chemicals while allowing air to pass through
  •     Impervious to climate: higher concrete durability eliminates damage from freeze-thaw cycles and scaling degradation

“Climatic issues, such as exposure of the concrete water tank, were a major factor in the OCWA reservoir project,” adds Chris Chen. “The waterproofing technology of Penetron Admix helps concrete resist damage from freeze-thaw cycles, such as cracks and even spalling. This increases the life-span of the concrete, effectively lowering maintenance costs.”

The technical background
Unlike metals, concrete is actually a porous material. This means concrete can deteriorate after repeated freezing and thawing. When freezing water expands, the expansion pressure will exceed the strength of concrete, leading to ever-larger cracks. Aside from this, its porosity permits water, salts, and other aggressive compounds to infiltrate the concrete, eventually coming in contact with the steel reinforcing bars. Over time, this leads to a significant reduction of the rebar area, causing loss in tensile strength of the concrete.

When Penetron products are applied to concrete the chemical reaction that follows creates insoluble crystals that fill voids and cracks in the concrete. This is not limited to the period after the initial setting of concrete. When no more water is present inside cracks, the crystals lie dormant. However, as soon as water reappears, the crystalline growth resumes and water cannot pass through these new micro-cracks. This ensures that the concrete remains waterproof throughout the life of the structure.

Penetron International, Ltd., is a leading manufacturer of integral crystalline waterproofing and repair products for concrete with a manufacturing and service network that spans more than 60 countries. For more information on Penetron please visit our website at http://www.penetron.com or contact Ann Martucci at 631-941-9700 or email at info(at)penetron.com.

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Ann Martucci
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