Through Wall Curtain Grouting

Prime Practices

Through Wall Curtain Grouting

Call: 1-800-321-7212

Scope of Work: Pressure injection of chemical grout through a structure wall via ports or packers, including manholes, walls, bulkheads, culverts



A below-grade structure is leaking. Oftentimes this causes erosion. Soil washes out from behind or underneath the structure. The result may mean a sinkhole, road depression, water main break, sewer infiltration, vault flooding or other major problem.



Inject chemical grout behind the structure to stabilize the soil, fill voids, and seal any leaks with a watertight barrier.


Prime Resins Options:

The Prime Resins products appropriate for curtain grouting, depending on the scenario, are:

  • Prime Flex 910 and Prime Flex 920 (polyurethane)
  • Hydro Gel SX (polyurethane) in a continuously wet environment
  • AR 800 (acrylate) in a very humid or continuously wet environment. Also performs in oil-tainted environments.
  • PR 10 (acrylamide) in a continuously wet environment


Step 1: Understand surrounding area

Prior to starting work, locate all utilities. Obtain a detailed drawing of all underground utilities in the work zone and ensure that all utilities are properly marked on the site. A soil analysis report may be needed to determine proper hole placement and to identify potential problem areas and natural differences in soil composition.


Step 2: Determine appropriate hole spacing

Determine appropriate hole spacing (grid) for injection to successfully seal, stabilize and fill area as shown in drawings. Test sections may be necessary to determine the best hole spacing depending on soil types and conditions encountered.


Typical spacing will vary between 12” – 48” in each direction. If multiple rows are needed, then each row should be offset half the space distance.

In some cases, it may be necessary to install soil probes or grout needles to transfer grout further out into the soils away from the structure.


Step 3: Check soil moisture

Prior to injecting, ensure the soils contain enough moisture to fully react the grout OR use a plural-component pump to inject water and grout simultaneously (twin streaming) through injection holes.

Use a ratio of 10:1 grout to water for twin streaming. We recommend a pump capable of injection pressures from 100 psi – 2500 psi. The flow rate of pumps should be .33 gpm minimum.

Manually operated or hand pumps are unacceptable. Do not use hand pumps. Void filling generally requires twin streaming due to the potential of high grout volume per injection point.


Note for soil grouting: To determine the best ratio of catalyst to grout, see the product data sheet for
more information about the percentage of Prime Kat and reaction times.

Offset grid pattern of ports for curtain grouting the basement wall of a high-rise apartment building


Step 4: Drilling injection holes

Drill holes as seen in the diagram from step two. The size of the holes depends on the size of the injection ports.


Step 5: Begin grouting

Grouting should start at the lowest point and work from left to right and up vertically throughout the grid pattern. Inject each location even with evidence of grout travel to that hole. The amount of grout injected at each hole is determined by soil conditions for that particular area.

Injection pressure will vary depending on soil conditions. In some cases, a second pass may be needed at each location to verify that voids are filled.

Note: Maintain a grout log to record the amount of grout and percentage of catalyst used for each hole.


Step 6: Clean-up

Flush the pump and hoses with Prime Resins Eco Flush. Do not use solvents to clean grout off human skin. Remove uncured polyurethane resin from tools with an approved solvent. Cured polyurethane can only be removed mechanically or with Prime Resins CGC (Cured Grout Cleaner). Seal all injection holes with Prime Plug 1, 2 or 3 hydraulic cement or Prime Gel 2500 Quick Bond as directed by the engineer or supervisor.


Safety Considerations
– Follow OSHA (or equivalent) guidelines for personal protection. Follow confined space entry safety requirements if working inside a manhole.
– When working with any chemical, read technical data and SDS information.
– Wear chemical safety glasses, goggles or a face shield when working with the material.
– Wear gloves and long-sleeved shirts to protect hands and skin.
– Do not use solvents to wash resin from skin. Use warm water and soap.
– Cleaning solvents for tools may be flammable – see container label and SDS for cleaning solvents.


Material List
– Prime Flex resin
– Eco Flush


Equipment List
– Hammer drill
– Bang-in ports or mechanical packers or grout needle or soil probes
– Pump capable of pressures from 100-2500 psi
– Personal protection equipment
– 3-4 clean, empty 5-gallon pails
– Low-speed drill with a mixing paddle if using Prime Flex 910 or 920


Related Content:
 Hydrophilic grout seals tunnel leaks at last (Niagara, Ontario)
 Curtain grouting a high-rise basement in the Bronx – AR 800 (New York City, NY)