Leak Repair

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Prime Flex 920 hydrophobic polyurethane injection resin

Prime Flex 920 is a single-component polyurethane injection resin used to seal gushing leaks, including wide gaps, in concrete where the structure is not subject to movement. This hydrophobic, super low viscosity polyurethane reacts with water and expands to form a closed cell, watertight, rigid foam. Due to its low viscosity, 920 is also used for permeation grouting of loose soils to consolidate soil particles and increase the load-bearing capacity. (For high strength or large void filling, see Prime Flex 985.) This material requires the use of Prime Kat or Kick Fast Kat to adjust the reaction time from 4-13 seconds. (See Material Preparation below.) 

Recommended Uses

  • Injection of gushing water leaks in below-grade structures
  • Injection of loose soils for stabilization
  • Curtain grouting manholes, pipe joints, tunnels, etc.
  • Point grouting

Typical Areas of Use

  • Sealing leaks and wide gaps in concrete. Examples:
    – Box culverts, tunnels (subway, water, utility, etc.)
    – Manholes, sanitary and storm pipes/structures
  • Curtain grouting below-grade structures. Examples:
    – Parking decks
    – Manholes
    – Foundations and basements
  • Permeation grouting for soil stabilization. Examples:
    – Roads and highways
    – Seawalls and retaining walls
    – Sinkhole perimeters (not filling the sinkhole—see 985)


  • Cheaper and less disruptive than replacement
  • Independently tested; verified as NSF/ANSI Standard 61 compliant for potable water contact
  • Super low viscosity: penetrates into fine areas
  • Pumped as a single component
  • Available in convenient cartridges
  • Up to 2900% expansion (unconfined)
  • Variable reaction (set) times
  • Meets Fla. DOT specification for soil injection of chemical grouts
  • Watertight on gushing leaks

Completed Projects

• Transbay Transit Center – San Francisco, CA    
 City of Olathe – Olathe, KS
• SLS Hotel – Miami, FL                                          
• City of Anderson – Anderson, SC
• Minneapolis LRT Tunnel – Minneapolis, MN    
• City of Tacoma – Tacoma, WA
 Curtis Palmer Dam – Corinth, NY                        
• Lake Park Marina, Lake Park, FL

Cured Characteristics

When cured, Prime Flex 920 exhibits a tensile strength (ASTM D-1623) of 41 p.s.i., tensile elongation (ASTM D-1623) of 3.4%, zero shrinkage, and a compressive strength (ASTM D695) of 1027 p.s.i. or 147,888 p.s.f. (with fine sand).

Material Preparation

Thoroughly mix materials using a low speed drill with a mixing paddle. Mixing by hand with a stir stick or simply shaking a container will not properly mix the material. Once catalyst has been added, the 920 will react upon contact with moisture. See technical data sheet for complete details.


5 gallon pails
50 gallon drums
250 gallon unit in 275 gallon tote
10:1 Quick Mix cartridges (case of 6 with Kick Fast catalyst)


Made in the U.S.A.