By BOSLAI – Leading Polyurethane Grout Manufacturer & Exporter from China
Polyurethane injection grout—also known as PU injection grout, PU grouting, polyurethane crack injection foam, or chemical injection grouting—is the industry’s most effective solution for stopping active water leaks in concrete structures. As a professional polyurethane grout manufacturer and exporter based in China, BOSLAI supplies high-performance hydrophilic (water-based) PU injection resin and hydrophobic (solvent-based/oil-soluble) PU grout to contractors, distributors, and engineering projects worldwide.
This guide covers the complete PU injection procedure, which applies universally to both water-reactive hydrophilic polyurethane and oil-soluble hydrophobic polyurethane injection grout.
What Is PU Injection Grouting?
Polyurethane (PU) injection grouting injects liquid resin under pressure into cracks, joints, or voids. Upon contacting moisture (hydrophilic) or activation (hydrophobic), it expands multiple times its volume to form a flexible, permanent watertight seal. Also called PU foam injection, PU injection waterproofing, or water stop foam grouting, this technique works from within the substrate—making it irreplaceable for active water leaks under pressure.
Common applications: basement waterproofing, tunnel leak sealing, foundation crack repair, water tank repair, swimming pool crack injection, retaining wall water stop, dam sealing, and curtain grouting.
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Step-by-Step PU Injection Procedure
1. Surface Preparation
Clean the work area: remove oil, moss, loose concrete, and debris. Locate all leakage points—cracks, construction joints, and honeycombed areas. Assess crack width and water flow rate to select between low-viscosity hydrophilic PU (for fine cracks) or fast-expanding hydrophobic PU foam (for gushing leaks).
2. Drilling and Hole Cleaning
Arrange injection holes in a staggered pattern 3–5 cm from the crack. Drill at a 45° angle using a 10–14 mm bit to a depth of 1/2 to 2/3 of structural thickness—never through the back side. Control hole spacing at 20–30 cm (closer for severe leaks). Flush all holes with high-pressure air or water to remove dust.
3. Packer Installation
Insert injection packers (nipples/ports) into cleaned holes and tighten with a T-handle wrench until the rubber ring expands firmly against the hole wall. Recommended: Apply rapid-setting plugging mortar along the crack surface as a sealing band to prevent grout leakage during injection—critical for high-pressure waterproofing work.
4. Grouting Operation
Equipment check: Check that the high-pressure grouting machine, pressure gauge, and hoses are in good condition. Connect the power supply (observe electrical safety precautions). Pour Polyurethane Injection Grout: Pour the polyurethane injection grout into the hopper (or barrel) of the grouting machine.
Connection: Attach the high-pressure hose nozzle of the grouting machine to the packer.
Injection process:
- Attach the hose nozzle to the first packer.
- Follow the sequence: “bottom-up for vertical cracks; end-to-end for horizontal cracks.”
- Start the pump and gradually increase pressure.
- Continue until grout overflows from adjacent packers OR pressure stabilizes at 0.3–0.8 MPa.
- Hold pressure for 1–3 minutes per hole, then close the valve and move to the next.
Secondary grouting (recommended): After 30 minutes, perform a top-up injection on key locations to compensate for curing shrinkage—essential for permanent leak sealing.
5. Packer Removal and Finishing
After 24 hours (once fully cured), remove packers with a wrench. Seal all holes with cement-based plugging mortar, epoxy mortar, or waterproof mortar for a smooth finish. Allow 24–48 hours curing before conducting acceptance tests.
Why Choose BOSLAI?
As a specialized China-based PU grout manufacturer, we deliver:
| Advantage | Detail |
| Factory-direct pricing | Competitive PU grout cost per kg for bulk orders |
| OEM/ODM available | Private labeling, custom packaging, tailored formulations |
| Dual-type supply | Both hydrophilic water-based PU and hydrophobic solvent-based PU |
| Global export experience | Shipping to Southeast Asia, Middle East, Africa, Latin America |
| Technical support | Guidance on product selection, injection procedures, troubleshooting |
Our polyurethane chemical grouts serve waterproofing contractors, civil engineers, mining operations, and infrastructure developers—from tunnel curtain grouting to residential basement repair.
Get Your PU Grout Quote Today
Whether you need fast-setting hydrophobic PU foam for emergency tunnel sealing or flexible hydrophilic PU gel for long-term basement waterproofing, BOSLAI is your reliable China PU grout supplier.
📩 Contact us → for bulk pricing, free samples, or TDS data sheets. We welcome distributors, contractors, wholesalers, and OEM partners worldwide.
BOSLAI — Your trusted partner for polyurethane injection grouting materials from China.
