Introduction
Injection grouting is a remedial waterproofing approach used when the positive side is not accessible. Specialized grouts are injected into cracks, joints, and porous concrete to block leak paths and, in some cases, restore structural integrity.
Advantages
- Effective for active leaks and inaccessible positive sides
- Targeted treatment of failure zones
- Can strengthen concrete internally with appropriate grout selection
- Versatile across basements, roofs, tanks, and junctions
Limitations
- Requires skilled applicators and controlled equipment
- Multiple injections may be required in heavy flow conditions
- PU foams alone may be temporary without complementary treatments
- Does not replace full-surface positive-side waterproofing
Types
- Cementitious grouts for general porosity
- Epoxy grouts for structural crack bonding
- Vinyl acrylate grouts for micro-porosity and seepage
- PU hydrophilic foams for running water leaks
- PU hydrophobic systems for rapid sealing with accelerators
- Combination systems, such as PU followed by vinyl acrylate, for severe leakages in Basement Retaining Walls
Application / Method Statement (Summary)
- Survey and mapping: Identify cracks and leakage zones.
- Drilling: Create a grid of NRV packers at 300–500 mm centers, depending on the intensity of leak.
- Injection: Start from the lowest point, inject until grout appears at the adjacent packer. This represents the radius coverage of each NRV
- Sealing: Remove or seal packers after cure and repair surface as required.
- Follow-up: Apply surface treatment if specified, such as crystalline coatings on the negative side.
Decision Guide
- Running leaks and high water ingress → PU hydrophilic foam, possibly staged with hydrophobic for rapid cut-off
- Structural cracks with load transfer needs → low-viscosity epoxy injection
- Damp seepage and micro-porosity → vinyl acrylate injection, often after initial dewatering
- Widespread porosity without active leaks → cementitious injection
Acceptance criteria
Grid of NRV packers installed at 300–500 mm centers or as designed.
Injection sequence followed from lowest to highest point.
Evidence of grout emergence at adjacent packers documented.
Appropriate grout selection validated against leakage condition.
QA records captured. Injection pressures, volumes per packer, photos.
Video
SpecX Masterclass: Injection Grouting — Coming soon
Disclaimer
SpecX is an industry initiative & a neutral resource, compiled from industry references and best practices. It is not brand-specific. Always cross-check with project requirements and local codes before finalizing specifications.