Permeation Grouting & Leak Repairs

THE CRACK INJECTION PROCESS

The type of product used for crack injection depends on the crack width, wall thickness and conditions present in the area being repaired. The steps in the crack injection process are:

1. Install Injection Ports: Surface ports can be used in low pressure injection situations. The port is placed over the crack and epoxy bonded to the surface. This avoids the need to drill and install injection nipples.
2. Seal the Surface: Seal over the surface ports leaving only the port holes uncovered.
3. Inject the Crack: Inject until the epoxy/polyurethane comes out of the port above. Plug the port and move up to the next port and repeat the process.
4. Remove the Ports: Allow the product to cure and then remove the ports.

Crack Injection is effective where individual cracks in the structure can be effectively sealed to prevent the ingress of water.

SELECTION OF CHEMICAL RESINS/GROUTS

FCS Concrete Repairs uses chemical grouts for stopping leaks in a variety of structures. By analysing the structure type and the size of the leak, FCS Concrete Repairs can determine which product and process works best for the given problem.

With weeping or small leaks, a major focus is on the viscosity, or thickness, of the resin. Low viscosity resins can easily penetrate the cracks and ensure that all cracked areas are repaired.

Hydrophilic chemical grouts are attracted to water and ‘chase moisture.’ In doing so, the grout follows all paths along the crack in order to reach and seal the leaks. For purposes of sealing leaks with chemical grouts, a hairline crack is considered one that is 1.6mm or less. Several products are independently verified to meet NSF/ANSI Standard 61.5 for contact with potable water, making them ideal for water treatment, transport and storage structures. Other areas of environmental sensitivity, such as seawalls, are also great candidates for our NSF compliant products.

With gushing or large leaks, quick reaction or ‘set’ times are important. This ensures that the resin has the opportunity to react with the water currently present and expand quickly enough to form a watertight, rigid foam before the leak can wash grout away. Set times can be controlled by catalysts or activators. Where hydrostatic pressures are high, a hydraulic cement patching material or oakum can be used to stop or slow the flow enough for the chemical grout to react.

Equally important is the expansion rate. Gushing leaks are caused by larger flows of water, meaning that a large area would need to be sealed in order to stop the leak. Using products with higher expansion rates allows for greater coverage of the void area. In below-grade structures, the large expansion rate also serves to fill any voids behind the structure and thus forms a curtain that serves as a 360-degree shield.

FCS Concrete Repairs selects products which have the necessary properties to repair the leak in the particular application. Such materials include products with the following properties:

• Acrylate, very low viscosity, low toxicity, elastomeric gel, for crack injection in structures
• Acrylate, very low viscosity, low toxicity, elastomeric gel, primarily for geotechnical applications, compliant for potable water use
• Hydrophilic, polyurethane, single-component, extra low viscosity, compliant for potable water use
• Hydrophilic, polyurethane, medium viscosity, single-component, for medium to wide cracks
• Hydrophobic, polyurethane, low viscosity, variable set time, compliant for potable water use
• Rapid cure polyurea non-sag paste for temporary surface seal prior to crack injection of epoxy or polyurethane grouts. Can be peeled off, leaving a clean surface.
• Hydraulic cement product to stop water flow prior to crack injection
  FCS Concrete Repairs recommends products supplied by Prime Resins.

Typical structures include:

FCS Concrete Repairs have the required equipment and experience to seal leaks in each of the following structures:

• footings
• foundations
• tanks
• below-grade carparks
• water treatment tanks
• elevator pits
• box culverts
• below-grade vaults, walls, pits or floors
• Uncontrolled Infiltration and Inflow  

Water and Sewage Authorities have problems with uncontrolled infiltration and inflows and chemical grouting is a cost-effective solution in controlling such infiltration and inflow in manholes and pipes.