Why Epoxy Is the Default Adhesive for Concrete
Epoxy adhesives have become the standard bonding material for concrete construction because they solve problems that no other adhesive family can match. They bond to cured concrete with tensile strength exceeding the concrete itself. They fill gaps and irregular surfaces. They cure without shrinkage. And they resist water, chemicals, and long-term creep under sustained load.
As a manufacturer producing epoxy systems for concrete applications since 2005, we offer specialized formulations for each major application — because a single "universal" epoxy cannot optimize performance across such different requirements.
Five Main Uses of Epoxy Adhesive in Concrete
1. Structural Bonding (Steel-to-Concrete, CFRP-to-Concrete)
The most demanding application. The epoxy adhesive forms a permanent structural connection that transfers load between the bonded elements and the concrete substrate. Products: Steel Bonding Adhesive (XQ-JG) for steel plate strengthening, Plate Bonding Adhesive (XQ-PB) for CFRP plates, Impregnation Resin (XQ-TJ) for carbon fiber fabric. Critical requirement: The adhesive bond must sustain loads for the design life of the structure (typically 50-100 years). This requires high creep resistance, durability under environmental exposure, and documented long-term performance data.2. Post-Installed Anchoring
Epoxy fills the gap between a steel element (threaded rod, rebar, bolt) and a drilled hole in concrete, creating a chemical bond that resists pull-out forces. Products: Our XQ-ZJ anchor adhesive series, available in pure epoxy, vinyl ester, and hybrid formulations for different conditions (dry/wet holes, cracked/uncracked concrete, ambient temperature ranges). Critical requirement: Bond strength must be sufficient to develop the yield capacity of the anchored steel element. Hole preparation quality is paramount.3. Crack Injection
Low-viscosity epoxy is injected into concrete cracks to restore structural continuity. The cured resin transfers tensile forces across the crack plane. Products: Low-Viscosity Injection Resin (XQ-LF-L) for fine cracks down to 0.1mm, Medium-Viscosity Resin (XQ-LF-M) for wider cracks up to 5mm. Critical requirement: The resin must fully penetrate the crack without leaving voids. Viscosity matched to crack width is essential.4. Concrete Repair Bonding
Epoxy-based repair mortars bond new repair material to existing concrete surfaces, particularly where thin sections (under 30mm) require high early strength. Products: Epoxy Repair Mortar (XQ-SJ-E), achieving ≥ 70 MPa compressive strength with excellent chemical resistance.5. Grouting
Epoxy grout fills gaps under machine bases, bridge bearings, and structural connections where zero shrinkage, high compressive strength, and chemical resistance are required. Products: Epoxy Grout (XQ-GJ-E), providing ≥ 80 MPa compressive strength with excellent chemical resistance and vibration dampening.Selecting the Right Concrete Epoxy
| Application | Viscosity Needed | Key Property | Our Product |
|---|---|---|---|
| Steel plate bonding | Thixotropic paste | Shear strength | XQ-JG |
| CFRP plate bonding | Thixotropic paste | Shear + bond | XQ-PB |
| Carbon fiber saturation | Low (500-1,500 mPa·s) | Fiber wetting | XQ-TJ |
| Bolt/rebar anchoring | Injectable | Bond strength | XQ-ZJ series |
| Fine crack injection | Very low (150-300 mPa·s) | Penetration | XQ-LF-L |
| Wide crack injection | Medium (1,000-2,000 mPa·s) | Gap filling | XQ-LF-M |
| Thin section repair | Paste mortar | Compressive strength | XQ-SJ-E |
| Machine base grouting | Pourable | Compressive + chemical | XQ-GJ-E |
Surface Preparation for Concrete Bonding
Regardless of the epoxy type, the concrete surface must be prepared to achieve reliable bond. The surface must be structurally sound — remove all laitance, loose material, coatings, and contamination by grinding or sandblasting. Exposed aggregate creates the best bonding surface. The surface must be within the correct moisture range, and surfaces must be clean and dust-free.
Testing tip: Apply a drop of water to the prepared surface. If it absorbs within seconds, the surface is properly prepared. If the water beads up or sits on the surface, contamination or laitance is still present.