Repair Systems
Injection resins (PU flexible)
Flexible and hydrophilic PU injection resin — technical reference for concrete cracking in Australian remedial building practice. Covers system selection, product comparisons, and brand equivalents.
What is injection resins (pu flexible)?
Polyurethane (PU) flexible injection resins are used to seal cracks in concrete and masonry that are subject to ongoing movement, seasonal thermal cycling, or water ingress. The resin is pumped under low pressure through ports installed along the crack at regular intervals, filling the void and curing to a flexible elastomeric material that accommodates future movement. Expanding foam variants react with moisture present in the crack to form a water-stopping seal, making them the product of choice for wet and actively leaking cracks in basements, water-retaining structures, and below-grade construction. This is a sealing solution, not a structural one — PU injection does not restore tensile continuity across the crack. The cause of cracking should be investigated and, where active movement is ongoing, addressed before injection is undertaken.
Product Reference
Scroll right to see all brands. Use each card's TDS link for verified specifications before specifying on any project.
Sika Injection-107 (hydrophilic) / Sika Injection-306 (hydrophobic)
PU resin, 600 mL
System Description
For active or dormant cracks. Hydrophilic type expands on contact with water. Min crack width 0.1 mm.
Technical Properties
- Flexible when cured — accommodates future movement in live or dynamic cracks
- Expanding foam variants effectively seal water-active and wet cracks
Limitations
- Not structural — does not restore tensile continuity or section strength across the crack
- May re-open if crack movement exceeds the product's elongation capacity
PROCUREMENT SOURCES
System Description
For active or dormant cracks. Hydrophilic type expands on contact with water. Min crack width 0.1 mm.
Technical Properties
- Flexible when cured — accommodates future movement in live or dynamic cracks
- Expanding foam variants effectively seal water-active and wet cracks
Limitations
- Not structural — does not restore tensile continuity or section strength across the crack
- May re-open if crack movement exceeds the product's elongation capacity
PROCUREMENT SOURCES
Fosroc Nitofill PU130
hydrophobic flexible polyurethane injection resin, 600 mL cartridge
System Description
For active or dormant cracks. Hydrophilic type expands on contact with water. Min crack width 0.1 mm.
Technical Properties
- Flexible when cured — accommodates future movement in live or dynamic cracks
- Expanding foam variants effectively seal water-active and wet cracks
Limitations
- Not structural — does not restore tensile continuity or section strength across the crack
- May re-open if crack movement exceeds the product's elongation capacity
PROCUREMENT SOURCES
Fosroc Nitofill PU150
hydrophilic expanding polyurethane injection resin, 600 mL
System Description
For active or dormant cracks. Hydrophilic type expands on contact with water. Min crack width 0.1 mm.
Technical Properties
- Flexible when cured — accommodates future movement in live or dynamic cracks
- Expanding foam variants effectively seal water-active and wet cracks
Limitations
- Not structural — does not restore tensile continuity or section strength across the crack
- May re-open if crack movement exceeds the product's elongation capacity
PROCUREMENT SOURCES
Tremco THC Injection Resin
expanding polyurethane injection resin, 600 mL
System Description
For active or dormant cracks. Hydrophilic type expands on contact with water. Min crack width 0.1 mm.
Technical Properties
- Flexible when cured — accommodates future movement in live or dynamic cracks
- Expanding foam variants effectively seal water-active and wet cracks
Limitations
- Not structural — does not restore tensile continuity or section strength across the crack
- May re-open if crack movement exceeds the product's elongation capacity
PROCUREMENT SOURCES
Brand Equivalents
Side-by-side view of equivalent products across all major brands.
| Material | Ardex | Sika | Fosroc | Tremco / Other | Parchem / Mapei |
|---|---|---|---|---|---|
| Polyurethane injection resin (flexible) | Ardex CE 300 | Sika Injection-107 (hydrophilic) / Sika Injection-306 (hydrophobic) | Fosroc Nitofill PU130 | Tremco THC Injection Resin | Fosroc Nitofill PU150 |
Disclaimer
Information is general only. Product selection must be confirmed against project requirements, substrate condition, exposure class, manufacturer technical data sheets, NCC requirements, Australian Standards (including AS 3600), and consultant or structural engineer specifications. Do not rely on this reference as a substitute for professional engineering advice.
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