What Is an Epoxy Crack Filler?
An epoxy crack filler is a two-component reactive resin system designed to fill, seal, or structurally repair cracks in concrete. Unlike polyurethane or acrylic crack fillers that remain somewhat flexible, epoxy crack fillers cure to a rigid, high-strength solid that restores the structural continuity of the concrete.
We manufacture three distinct types of epoxy crack filling products, each designed for specific crack widths and repair objectives.
Three Types of Epoxy Crack Filler
1. Injection Resin (XQ-LF-L / XQ-LF-M)
For structural crack repair where the goal is to restore load transfer across the crack. Low viscosity (XQ-LF-L): 150-300 mPa·s — penetrates cracks as narrow as 0.1mm. Cured tensile strength exceeds 40 MPa, making the repaired crack stronger than the surrounding concrete. Medium viscosity (XQ-LF-M): 1,000-2,000 mPa·s — designed for wider cracks (0.3-5mm) where the low-viscosity resin would flow through and out the other side. Higher gap-filling ability with 35 MPa tensile strength. Application: Pressure injection at 0.2-0.4 MPa through ports bonded along the crack line.2. Surface Seal Paste (XQ-LF-SS)
A thixotropic epoxy paste applied to the concrete surface to seal crack openings before injection or to seal non-structural surface cracks. Purpose: During crack injection, the surface seal prevents injected resin from leaking out through the crack opening. It can also be used alone to seal dormant surface cracks that do not require structural repair. Application: Trowel or spatula application to a width of 20-30mm centered on the crack line. Cure time is 4-6 hours before injection can begin.3. Concrete Floor Crack Sealer (XQ-LF-FC)
A self-leveling low-viscosity epoxy specifically formulated for horizontal crack repair in floors, slabs, and pavements. Key feature: Self-leveling — simply pour along the crack and the resin flows into the opening by gravity, filling it from bottom to top. No injection equipment needed. Application: Clean the crack, apply masking tape along both sides (to control spread), pour resin along the crack, allow gravity fill, remove tape after initial cure, and sand flush.When to Use Each Type
| Scenario | Product | Method |
|---|---|---|
| Structural crack in beam or column | XQ-LF-L or XQ-LF-M | Pressure injection |
| Crack in basement wall (water seepage) | XQ-LF-L (if dormant) | Pressure injection |
| Floor slab crack | XQ-LF-FC | Gravity pour |
| Surface seal before injection | XQ-LF-SS | Trowel application |
| Hairline crack, aesthetic only | XQ-LF-SS | Surface application |
| Active crack (still moving) | XQ-LF-PU (polyurethane) | Pressure injection |
Performance After Repair
A properly executed epoxy crack injection creates a repair that is structurally superior to the original concrete. Our low-viscosity injection resin (XQ-LF-L) achieves a tensile strength greater than 40 MPa after cure, while typical concrete has a tensile strength of only 2-4 MPa.
In pull-off bond tests, the failure occurs in the concrete substrate, not at the epoxy-concrete interface or within the epoxy itself. This confirms that the repaired section is at least as strong as the uncracked concrete.
However, this performance is only achieved with proper crack preparation and injection technique. Contaminated cracks (oil, grease, organic growth), improperly sealed cracks (resin leakage during injection), or incomplete filling (air pockets, insufficient injection pressure) will all reduce the effectiveness of the repair.
Shelf Life and Storage
All our epoxy crack filling products have a 12-month shelf life when stored in original sealed packaging at 5-25°C. Store away from direct sunlight and heat sources. Once opened, components should be used within 6 months.
The products are supplied in dual-cartridge systems (injection resins) or pre-measured kits (floor sealer, surface seal paste) to ensure correct mixing ratios in the field.
View our complete crack repair range or request a quote for your project.