Leak Repair

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Prime Flex 900 XLV polyurethane resin



Prime Flex 900 XLV polyurethane resin is a low viscosity, hydrophilic resin that reacts with water and expands to form a closed cell, watertight foam. It is typically injected under pressure to seal actively leaking joints and cracks in concrete structures, including hairline cracks. This product is independently tested and proven to meet NSF/ANSI Standard 61.5 for contact with potable water.

Recommended Uses

  • Injecting hairline cracks, expansion joints, wide cracks, pipe joints, or pipe penetrations
  • Sealing active leaks in above- or below-grade concrete structures
  • Oil-free oakum or open cell backer rod may be soaked in Prime Flex 900 XLV to create a watertight gasket


Typical Areas of Use

  • Water treatment tanks
  • Dams
  • Below-grade concrete walls
  • Tunnels, manholes
  • Elevator service pits



  • NSF/ANSI Standard 61.5 compliant for contact with potable water
  • Single-component. No catalyst or accelerators needed. Pump material straight out of the pail.
  • Extremely tough and flexible. Can expand and contract parallel to the crack in varying temperatures.
  • Up to 600% expansion (unconfined)
  • Low viscosity will penetrate tight cracks


Cured Characteristics

This one-component liquid has a low viscosity, allowing it to penetrate hairline cracks deep into the structure. When the material contacts water, it reacts to form a white, flexible gel-like foam that acts as a barrier, sealing the cracks that allowed water to leak.

As the foam reacts, it expands to fill the space and bond to the concrete to hold it in place, creating a closed cell mass that does not allow water to pass through or around it. The foam’s flexibility allows it to expand and contract along with the structure it has sealed, so it remains water tight despite temperature fluctuations.



• 1 gallon jugs (case of 4)
• 5 gallon pails
• 2:1 Quick Mix cartridges (10 per case)

Packaged under a dry nitrogen blanket.


Made in the U.S.A.