Product Description

Prime Flex 940 polyurethane resin is a very low viscosity, hydrophobic resin that reacts with water and expands to form a closed cell, watertight flexible foam. This grout requires Prime Kat or Kick Fast catalyst, but after mixing is pumped as a single component. The set time can be varied with the catalyst concentration. This resin is used for sealing actively leaking joints and cracks in concrete structures, particularly those subject to movement or vibration. It is verified to meet NSF/ANSI Standard 61.5 for contact with potable water.

Recommended Uses

Sealing active leaks in above- or below-grade concrete structures.
Filling voids where flexibility is required, including areas with vibration and minor movement

Typical Areas of Use

  • Pipe joints
  • Box culverts
  • Tunnels
  • Storm sewers
  • Retaining walls
  • Seawalls
  • Below-grade parking decks
  • Earthen dams


The foam’s flexibility allows it to expand and contract along with the structure it has sealed, so it remains watertight despite temperature fluctuations or minor movement. Its low viscosity makes it suitable for hairline cracks (though Prime Flex 900 XLV is a better choice for hairline cracks). As the foam reacts, it expands to fill the space, creating a closed-cell mass that does not allow water to pass through or around it.

  • Pumped as a single component
  • NSF/ANSI 61.5 compliant for contact with drinking water
  • Controllable set time
  • Watertight
  • Very low viscosity for good penetration
  • MDI-based


Prime Flex 940          45 lb. pails; Quick Mix cartridges (6 per case with 10% Kick Fast catalyst and 6 static mixers)  (750ml x 75ml) 10:1
Prime Kat catalyst    66 oz unit or 5 gallon pail
Kick Fast Kat             66 oz unit or 5 gallon pail


Made in the U.S.A.


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