Leak Repair with Polyurethane Injection Resins

Water leaking through cracks in concrete or masonry can be sealed by pressure injection of our Prime Flex polyurethane resins.  The resins will react with water and expand to form a water tight gasket inside or behind the structure.  Select Resources/How To Procedures for installation techniques.

Hairline Cracks

Hairline cracks are defined as cracks less than 1/16”.  These cracks can be the most difficult to seal as it is tough to force a thick resin into a tight crack.  For this procedure, we have developed Prime Flex 900 XLV.  It’s a thin resin that forms a tough, flexible, and water tight seal when it comes into contact with water.  It forms a tenacious bond to wet concrete and is quite frankly the best injection product on the market for sealing leaks.

Wide Cracks and Joints

Joints are easy to seal if you know the proper procedures.  Prime Flex 900 XLV, while great in tight cracks, works equally as well in sealing wide joints.  Just make sure there is enough water to give you the highest quality seal and pressurize the joint with the foam to make it tight.

Gushing Leaks

These can be especially challenging because large quantities of water can wash out the resin before it sets.  That is why we have developed a series of products and techniques to tackle gushers.  Prime Flex EXP is explosively expansive to shut down gushing leaks in seconds.  Prime Flex 920 utilizes a catalyst so the set time is adjustable on site.  It can expand up to 29 times its original volume, and it forms a rigid foam.  Try injecting these materials behind the structure for best results.

Dry Cracks

Some cracks are wet after a rain but dry at other times.   You can still repair these cracks with Prime Flex 900 XLV.  Just make sure there is enough moisture by injecting water before or at the same time as the resin (“Quick Mix” cartridges, two component pumps, or injecting water first will accomplish this).

Manholes

Leaks in manholes can be sealed in various ways.  Gushing leaks can be shut down with highly expansive foam such as Prime Flex EXP or Prime Flex 920.  Brick manholes can be sealed by curtain grouting with Prime Flex Hydro Gel SX, which forms a flexible foam or gel depending on the amount of water it mixes with before it sets (about 60 seconds).  Precast joints can be injected with Prime Flex 900 XLV for a permanent seal.

Coatings

Our Prime Guard 7500 polyurea coating does an excellent job of surface sealing leaks if the surface is dry.  It is extremely flexible, tough, and durable.  It is available in our “Quick Spray” cartridge system, which is the most convenient way to apply polyurea coatings.

Hydraulic Cement

Prime Plug hydraulic cement is a great way to stop leaks temporarily prior to injecting with Prime Flex.  It is available in three set times, from one minute to 12 minutes.  We don’t recommend hydraulic cement as a permanent solution because the water pressure will be working against this negative side band-aid continuously.  The best seal is an internal seal (inside the crack) or a positive side seal (on the back side of the structure so the water pressure pushes the seal tight against the concrete or masonry) using Prime Flex resins.