Concrete Spalling & Cancer Repair
Specialist repair of concrete affected by reinforcement corrosion (“concrete cancer”) to restore structural capacity, prevent further deterioration, and extend the service life of the structure.

Concrete spalling — often referred to as concrete cancer — occurs when embedded steel reinforcement corrodes. As the steel rusts, it expands up to seven times its original volume, cracking the surrounding concrete and accelerating deterioration. Left untreated, it can compromise the safety, structural integrity, and waterproofing of the building.

‍

In Sydney's coastal environment, concrete spalling is common in buildings constructed between the 1960s and 1990s when low concrete cover over reinforcement was standard practice. Balcony edges, parapets, soffits, and facades are particularly vulnerable. The earlier the problem is caught and repaired, the less invasive and costly the remediation.

How We Diagnose & Repair

  1. Condition Assessment
    • Visual inspection to identify cracking, rust staining, and delamination.
    • Tap testing, cover meter readings, and carbonation depth checks.
    • If necessary, chloride testing to determine salt contamination levels.
  2. Breakout & Removal
    • Carefully break out all loose and contaminated concrete to expose clean, solid material.
    • Extend removal to sound concrete to prevent future propagation.
  3. Steel Reinforcement Treatment
    • Mechanically clean exposed rebar to bright metal finish (Sa 2½ standard).
    • Apply high-performance anti-corrosion primers or zinc-rich coatings to inhibit further rusting.
  4. Structural Restoration
    • Where reinforcement is severely corroded, cut out and replace with new steel bars lapped into existing reinforcement.
    • Reinstate concrete with proprietary high-build repair mortars designed for structural applications, matching the strength and modulus of existing concrete.
  5. Protective Finishes
    • Apply anti-carbonation coatings or waterproof membranes to prevent moisture and CO₂ ingress.
    • Integrate with existing façade waterproofing to ensure continuity of protection.

Where We Repair Concrete Spalling

  • Balcony Edges & Slabs – High exposure to rain and salts.
  • Façades & Parapets – Frequent carbonation and wind-driven rain exposure.
  • Roof Slabs & Podiums – Thermal cycling and ponding water.
  • Basement Walls & Soffits – Chloride-rich groundwater intrusion.
  • Structural Beams & Columns – Load-bearing elements where failure is not an option.

Why Our Method is Different

  • Engineering-Driven Approach: All repairs designed in consultation with structural engineers.
  • Long-Term Protection: Not just patching — we stop the root cause of corrosion.
  • Compliance Guaranteed: Works delivered in accordance with AS 3600 (Concrete Structures) and manufacturers' specifications for warranty validity.

Frequently Asked Questions

How do I know if my building has concrete spalling?

The most visible signs are rust staining on concrete surfaces, chunks of concrete falling away, cracking along the line of reinforcement bars, and hollow sounds when you tap the surface. In multi-storey buildings, soffits and balcony edges are the most common early-warning locations. If you see any of these, it's worth getting a professional assessment — the defect spreads faster than most people expect.

Is concrete spalling a safety risk?

Yes. Falling concrete is a real hazard to occupants and the public below, particularly from balcony edges and soffits above pedestrian areas. Beyond the immediate falling-debris risk, progressive reinforcement corrosion can compromise the load-bearing capacity of structural elements. Strata managers and owners corporations have a duty of care to address known spalling promptly.

Can concrete spalling be patched, or does it require full replacement?

In most cases, targeted repair — breaking out the damaged area, treating the reinforcement, and reinstating with structural repair mortar — is sufficient and far more cost-effective than full replacement. The key is addressing all affected areas and treating the steel properly so the repair doesn't fail within a few years. We use Sika, Parchem, and Fosroc repair systems matched to the original concrete specification.

How long does a concrete spalling repair last?

When done properly — with correct steel treatment, quality structural repair mortars, and protective coatings — repairs are designed to last 20+ years. The critical factor is not just the mortar quality but ensuring anti-corrosion treatment of the steel is thorough and the protective coating system prevents future moisture and carbonation ingress.

Does concrete spalling repair require a strata committee vote?

For works above a certain dollar threshold, yes — most strata schemes require a general meeting vote for capital works. However, emergency or urgent safety repairs can typically be authorised by the strata committee under urgent maintenance provisions. We can provide written assessment reports and scopes of works documentation to support strata committee decision-making and tender processes.

Related Services

A proper concrete cancer repair isn't just about filling holes — it's about arresting the corrosion process entirely and restoring the structure to full load-bearing capacity. With Atomic Projects, you get repairs that last, not just cosmetic fixes that hide the problem until it comes back worse.

As a Class 2 Registered Builder with over 10 years of experience in remedial works across Sydney, we deliver concrete spalling repairs backed by engineering specification and quality assurance at every stage. Call us on 0410 515 509 or email hello@atomicprojects.com.au to arrange an inspection.