Structural Epoxy Injection & Concrete Repair Specialists

Specialist epoxy crack injection for structural concrete repair in NSW u2014 restoring load-bearing capacity to cracked beams, slabs, walls and civil structures using Normet and Sika injection systems.

What Is Epoxy Crack Injection?

Epoxy injection is a structural repair method used to restore cracked concrete to near-original load-bearing capacity. Unlike polyurethane injection u2014 which stops water ingress but has no structural strength u2014 epoxy injection bonds the two faces of a crack back together with a rigid adhesive that, when fully cured, has a compressive strength typically exceeding that of the surrounding concrete.

The critical distinction is the crack condition: epoxy injection must only be applied to dry or damp (but not actively flowing) cracks. Water in the crack prevents the epoxy resin from bonding to the crack faces, resulting in an injection that fills the void but achieves no structural bond. This is why the sequence of repair matters: if a structural crack is also actively leaking, it must be treated first with polyurethane injection (to stop the water), allowed to dry, and then treated with epoxy for structural restoration.

Epoxy injection is not appropriate for all concrete cracks. It is the correct method when:

The crack is structurally significant u2014 it has reduced the load capacity of a beam, column, wall, or slab
The crack is dormant (not continuing to widen or move) u2014 injecting epoxy into an actively moving crack will result in re-fracture adjacent to the bonded zone
The crack is dry or only slightly damp u2014 no active water flow
Structural continuity needs to be restored u2014 not just water stopped

Epoxy injection is not appropriate when the crack is actively moving (ongoing settlement, thermal cycling in an exposed structure), when the concrete around the crack is severely degraded (carbonated, chloride-contaminated to the point of delamination), or when the crack width is less than approximately 0.1mm (too narrow for resin penetration without specialist ultra-low viscosity products).

Where Epoxy Injection Is Used

Econyc carries out epoxy crack injection on a wide range of structural concrete elements across NSW:

Structural beams and columns u2014 flexural and shear cracks in concrete beams and columns that have reduced the structural element’s design capacity. Epoxy injection restores the composite action of the cracked section and returns the element to its design strength.
Carpark slabs and transfer slabs u2014 shrinkage and settlement cracks in carpark slabs are injected to prevent water and chloride ingress through the crack, and to restore slab continuity where cracks are structurally significant.
Bridge decks and civil infrastructure u2014 epoxy injection is used on bridge decks, abutments, and retaining structures where crack repair is specified by the structural engineer as part of a broader remediation programme.
Retaining walls u2014 dormant shrinkage and settlement cracks in retaining walls are injected to restore structural continuity and prevent water infiltration through the crack.
Industrial and warehouse slabs u2014 construction cracks and settlement cracks in industrial floor slabs are epoxy-injected to prevent further crack propagation and to restore the load-bearing capacity required for forklift and heavy vehicle traffic.
Pre-stressed and post-tensioned concrete u2014 crack repair in pre-stressed elements is particularly important because the presence of a crack may compromise tendon protection. Epoxy injection of dormant cracks restores the protective concrete cover around the tendons.

Our Epoxy Injection Process

Epoxy injection is a precision process u2014 the resin must penetrate the full depth and width of the crack under controlled conditions to achieve the required structural bond. Econyc’s process:

Structural assessment and crack classification u2014 the crack is assessed for width, depth, extent, orientation, and cause. We confirm that the crack is dormant (not active) and dry or damp. If the crack shows signs of ongoing movement (fresh concrete dust, progressively widening, associated with live loads), epoxy injection is not appropriate and we will advise accordingly. If the crack is wet or actively leaking, PU injection must be completed first.
Surface preparation u2014 the crack face is cleaned using compressed air and, where necessary, mechanical cleaning to remove dust, oil, and contamination that would prevent epoxy adhesion. The concrete must be structurally sound at the crack faces u2014 any delaminated or carbonated material is removed.
Port installation u2014 injection ports (packers) are drilled at 45 degrees to intersect the crack at mid-depth. Port spacing is calculated based on crack width: narrower cracks require closer port spacing (100u2013150mm centres) because the low-viscosity resin travels less distance per injection cycle.
Surface seal application u2014 an epoxy paste is applied along the crack surface between ports to seal the crack externally and prevent resin from flowing out during injection. This surface seal must cure partially before injection begins.
Resin injection u2014 low-viscosity epoxy resin (Normet or Sika Injection-201 CE) is injected at low, controlled pressure starting from the lowest or innermost port. The low pressure allows the resin to penetrate the full crack depth by capillary action. Injection continues at each port until resin appears at the adjacent port. High-pressure injection is not used for epoxy u2014 it can cause the surface seal to fail and the resin to bypass the crack rather than penetrating it.
Cure period u2014 epoxy resin requires 12u201324 hours to achieve structural strength (temperature-dependent). The structure must not be loaded during this period. We advise on any temporary load restrictions required during cure.
Port removal and surface finishing u2014 after cure, ports are removed and the holes patched with polymer mortar. The surface seal is ground back flush with the concrete surface if required by the specification.
Documentation u2014 a completion report documenting crack locations, port spacing, product used, volumes injected, and application conditions (temperature, humidity) is provided. Pull-off testing or core sampling can be arranged for critical structural elements where the engineer requires confirmation of bond strength.

Products We Use u2014 Normet and Sika Epoxy Systems

Econyc uses epoxy injection resins from Normet and Sika u2014 two manufacturers with proven products specifically designed for structural concrete repair by injection.

Normet epoxy injection systems u2014 Normet’s structural epoxy range is used for crack injection in civil and building structures. Low-viscosity formulations (typically <200 mPa.s) allow penetration of cracks down to 0.1u20130.2mm width. Normet’s products are used on major bridge, tunnel, and building structure repair projects across Australia and internationally.

Sika Injection-201 CE u2014 a two-component, low-viscosity epoxy injection resin specifically formulated for structural crack repair. Sika Injection-201 CE achieves a compressive strength exceeding 60 MPa and a tensile adhesion strength exceeding the tensile strength of the surrounding concrete when correctly applied. It is compatible with damp (but not wet) concrete and has a controlled working time that allows thorough penetration of fine cracks before gel formation begins.

For surface sealing between injection ports, we use Sika’s epoxy paste or mortar products, which provide the bond strength and rigidity required to contain the injected resin within the crack during the injection and cure period.

All injection work is performed using low-pressure injection pumps appropriate for epoxy systems u2014 not the high-pressure equipment used for PU injection. Correct equipment selection is as important as product selection for achieving the required penetration and structural bond.

Important: No Warranty on Epoxy Injection Work

Econyc does not provide a workmanship warranty on epoxy crack injection. This is consistent with standard industry practice for injection waterproofing and structural repair by injection, and the reasons are important for building owners and engineers to understand.

Epoxy injection repairs a crack that exists because of an event or process u2014 structural overload, shrinkage, settlement, or thermal movement u2014 that may or may not have fully resolved at the time of injection. The long-term performance of the injected repair depends entirely on factors outside the injection contractor’s control:

Ongoing structural movement u2014 if the cause of cracking has not been fully resolved (e.g., live load stresses continue to cycle, settlement continues, or adjacent construction causes vibration), the repaired section may re-crack adjacent to the injection zone. Epoxy is rigid and will not accommodate movement u2014 re-fracture occurs in the surrounding concrete rather than at the bond line.
Substrate quality u2014 the strength of the epoxy bond is limited by the tensile strength of the concrete at the crack faces. In heavily carbonated, chloride-contaminated, or low-strength concrete, the bond strength achievable by injection is lower than in sound concrete, regardless of the quality of the resin used.
Structural assessment accuracy u2014 injection repairs complement, rather than replace, structural assessment and remediation. If the structural cause of cracking has not been addressed by a structural engineer (e.g., inadequate reinforcement, design overload), injection alone will not provide a durable solution.

What Econyc guarantees is that the injection has been carried out correctly u2014 the correct product applied by a trained operator using appropriate equipment, with full penetration of the crack confirmed by resin appearance at adjacent ports. Our completion reports provide the documentation that structural engineers and building owners need to assess the adequacy of the injection and make informed decisions about any additional structural measures required. We do not, however, warrant the long-term performance of an injection repair in a substrate and loading environment that is outside our control.

Epoxy vs. Polyurethane: Choosing the Right Injection Method

The decision between epoxy and polyurethane injection is not a matter of preference u2014 it is determined by the crack condition and the repair objective.

Use polyurethane injection when: the crack is wet or actively leaking; stopping water ingress is the primary objective; the crack may be subject to ongoing minor movement (PU foam is flexible); structural restoration is not required.
Use epoxy injection when: the crack is dry or only damp (no active water); restoring structural strength and continuity is required; the crack is dormant (not continuing to widen); a rigid bond is required.
Use PU injection followed by epoxy injection when: the crack is both structurally significant and actively leaking u2014 PU injection first to stop the water and allow the crack to dry, then epoxy injection for structural restoration.

Making the wrong choice has direct cost consequences: epoxy applied to a wet crack will not bond and the injection will need to be redone; PU applied where structural restoration was needed will stop the water but leave the structure compromised. Econyc’s pre-injection assessment identifies the correct method before any drilling begins u2014 we do not charge for this assessment, and we will tell you honestly if injection is not the right solution for your specific situation.

Frequently Asked Questions u2014 Epoxy Injection NSW

Can epoxy injection be used on live structures (buildings in use)?
nYes u2014 and in fact, the majority of our epoxy injection work is on occupied buildings. The process is low-disruption: drilling and injection generates some noise and vibration, but the work area itself is small. The main requirement is that the structural element being injected is not subject to significant load during the 12u201324 hour cure period. We will advise on any temporary load restrictions required for the specific element.

How do I know if my crack needs epoxy injection or just a surface filler?
nSurface fillers (caulk, polymer mortar, concrete patching compounds) address the cosmetic appearance of a crack but do not restore structural continuity. If the crack has reduced the structural capacity of the element u2014 a beam, column, or slab u2014 surface patching is not an adequate repair. Structural engineers typically specify epoxy injection for cracks that are structurally significant. If you are unsure, have the crack assessed by a structural engineer before specifying any repair method.

Will the injected crack be visible after repair?
nThe injection ports leave small holes (typically 12u201316mm diameter) that are patched with polymer mortar after the ports are removed. The crack itself, once surface-sealed and injected, will typically be visible as a hairline where the sealant and concrete meet u2014 it will not disappear entirely. For architecturally exposed concrete where appearance is critical, we can discuss surface finishing options.

Can epoxy injection be used on cracks in post-tensioned slabs?
nYes, but with important precautions. In post-tensioned slabs, the location of tendons must be identified (using a tendon locator or as-built drawings) before drilling injection ports. Drilling into a tendon can be catastrophic. Econyc uses tendon detection equipment and coordinates with structural engineers on all post-tensioned slab injection work.

How is the quality of epoxy injection verified?
nFull penetration of the crack is confirmed during injection by resin appearance at adjacent ports. For critical structural elements, pull-off testing can be used to verify the bond strength achieved after cure. Core samples can also be taken and examined to confirm the crack has been fully filled. We include these quality assurance steps in our completion reports for projects where the structural engineer has specified verification testing.

Ready to Get Started?

Contact Econyc today for a free site inspection and fixed-price quote. Licensed, insured, and fully compliant with Australian waterproofing standards.