Stages of Negative-Side Water Sealing by Polyurethane Resin Injection
(Negative Water Pressure Waterproofing – PU Resin Injection)
Overview
Polyurethane (PU) resin injection is a highly effective method for sealing water ingress and leaks under negative (outside-to-inside) hydrostatic pressure in concrete structures—such as basements, underground tanks, tunnels, joints, and cracks. This process creates a resilient, elastic barrier capable of enduring cyclic wetting and pressure fluctuations.
RBS-CONTECH, member of Clinic Beton Iran Group, offers advanced polyurethane injection resins for these purposes, fully conforming with global standards.
Step-by-Step Execution Method
Assessment and Marking
Inspect structure for the source(s) of seepage, visible cracks, joints, honeycombing, or damp zones.
Mark points along the leak path for packer (injection port) installation—typically at 20–50 cm intervals.
Drilling Injection Holes
Drill holes at 45–60 degrees to the surface, intersecting the crack/joint at mid-depth (ensure sufficient penetration).
Use suitable diameter for the chosen packer (usually 10–18 mm).
Cleaning & Packer Installation
Flush the holes to remove dust, debris, and loose particles.
Insert and tightly fix mechanical or adhesive injection packers.
Preparation of Polyurethane Injection Resin
Mix PU resin and accelerator/activator (if two-component system), following manufacturer’s datasheet instructions.
Choose the appropriate resin grade (hydrophobic or hydrophilic), depending on the presence and quantity of water.
Injection Process
Use a high-pressure, two-component injection pump suited for PU resin.
Begin injection from the lowest point (for vertical surfaces) or from one end (for horizontal surfaces).
Inject until refusal (resin visibly emerges from adjacent packers or cracks).
Sequentially inject through all installed packers, monitoring pressure and resin flow.
Pressure Relief and Cleaning
Allow sufficient reaction/curing time (as per product, usually 15–60 minutes).
Remove packers after resin cures.
Plug injection holes with appropriate non-shrink grout.
Final Inspection and Surface Treatment
Visually inspect for leak cessation; re-inject at any persistent seepage points if necessary.
If specified, apply a negative or positive-side waterproofing coating for additional protection.
Key Standards & Guidelines
ASTM F2304 – Standard Practice for Sealing Leaks Using Chemical Grouts
EN 1504-5 – Products and systems for the protection and repair of concrete structures — Injection of concrete.
ACI 503.7 – Specification for Crack Repair by Epoxy Injection (relevant in general injection practice)
Manufacturer specifications and local norms
Critical Execution Notes
Always use protective equipment (PPE: gloves, goggles, mask) when handling PU resin.
Do not over-pressurize: Excessive injection pressure may cause new cracks or damage structural integrity.
Hydrophilic PU is suited for wet cracks; hydrophobic for dry or minor moisture.
Ensure compatibility of PU system with the structure, presence of potable water, and expected movements.
Temperature and substrate moisture can affect curing times—follow manufacturer’s recommendations.
Document location of injected lines and volume used for quality control.
Advantages & Applications
Provides long-term, elastic sealing for active leaks under negative pressure.
Suitable for concrete, masonry, dams, retaining walls, elevator pits, basements.
Fast-curing; structure can generally be put back into service promptly.
No major surface demolition or heavy repairs needed.
Technical Support & Reference
For the latest technical datasheets, selection guides, application videos, and certified specialists, contact:
Clinic Beton Iran Group (RBS-CONTECH division)
Website: https://www.clinicbeton.com
International: https://www.rbs-contech.com
Email: clinicbeton.com@gmail.com
Tel: +98 21 88070173, +98 21 88584906