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Sometimes confused with concrete cancer, concrete spalling is the first stage of the process that leads to concrete cancer. Understanding and treating concrete spalling is crucial to ensure it doesn’t escalate and lead to major and costly remediation.
Within every concrete building is a steel framework of bars or mesh. Any exposure to air or water from a small crack or fracture causes that steel to corrode. When the metal degrades, it provides more space for water to enter the internal structure, accelerating the process.
Concrete spalling describes the initial state when the concrete begins to break away, and common signs include cracking, crumbling or flaking concrete, rust stains, bubbling on the concrete or cement render and internal leaks from the roof or walls.
Concrete cancer refers to the spread of concrete spalling, something that is inevitable without treatment.
Finding and filling small cracks will help stop the spread of concrete spalling, but it’s a band-aid remedy only. Concrete spalling and cancer cannot be remedied without structural intervention. To combat both, you need professional detection and an end-to-end solution from skilled waterproofing professionals.
Once we have diagnosed the precise cause and full extent of the concrete cancer, we will design a solution that fits the type of property and location, whether it’s a flat roof, balcony, basement or rooftop garden. For properties near the ocean, for instance, we might opt for a site-specific electrochemical treatment.
Generally, we will need to remove the damaged concrete, clean and remove the metal framework and replace it with new material.
We’ll then apply an anti-carbonation coating or another specialist coating to strengthen and preserve the concrete.
At Danrae Group, we regularly see the effects of concrete spalling and cancer, and it’s important to realise that slapdash remedies and poor workmanship will never solve the issue. A comprehensive, long-term solution is critical.
As just one example of what might be involved, this is an overview of a concrete spalling fix we provided for a strata apartment in Rose Bay.
Preparation – We removed all damaged concrete, rust and loose material over the reinforced bar, blast-cleaned the metal, cleaned the exposed concrete, prepared the surface then applied a bonding primer. We then applied two coats of corrosion protection coating to the steel bars.
Concrete repair – We applied structural repair mortar, pressing it well into the substrate. We applied several layers (with 24 hours drying time required between layers) then a bonding primer. We finished with hand and spray application, applying layers to a minimum of 30mm above the steel reinforcement.
Curing and finishing – We applied a resin adhesive, installed a carbon fibre strip, maximum 500mm centre to centre with fibre direction parallel to existing steel bar reinforcements. We organised for the apartment directly above the damaged concrete to be vacant for 24 hours to ensure proper curing, then finished by applying an adhesive and carbon fibre strip.
Concrete spalling is common and highly damaging if left untreated. It will always worsen, leading to more extensive and more expensive repairs. And it takes a skilled team to provide a high-quality and permanent waterproofing solution.
Danrae Group provides holistic solutions that include diagnostic, design, remediation, waterproofing and ongoing preventative maintenance, and our end-to-end project management covers everything from council permits to crane hire and all stakeholder communication.