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Water entering concrete cracks and spalling concrete

Concrete cancer - spalling concrete staircase - Waterstop Solutions

Water entering concrete cracks and spalling concrete

Once water enters a crack, it is usually only a matter of time before the water leads to oxidization of the rebar/reinforcing steel.


Concrete steps can crack and break up over time. Thermal changes and exposure to rain and driving wind can lead to water ingress through cracks in the stairs. For water, it is a simple task to pass through something as small a hairline crack and water has a way of seeking out the passage of least resistance.

In addition to being unsightly, this damage can sometimes lead to unsafe conditions. If parts break off, there is a risk of injuring a person walking by aswell as damage to other property.


Cracked concrete, blistering concrete render, breached protective coatings and waterproofing defects often invites water entering the structure, which leads to concrete spalling, rusting reinforcement steel and concrete deterioration if they are left untreated. The corrosion of reinforcement steel leads to reduced resistance of the steel bars, which depending on severity, may negatively affect the load-bearing capacity and service life of the concrete.

Concrete cancer is rust originating deep within the concrete – specifically within the reinforcing steel. As steel rusts, it can expand up to 7 times its original size causing the surrounding concrete to be displaced. The problem is very likely to be much more extensive than what is apparent on the concrete surface. The cancer will likely have spread along the reinforcing in each direction. It is impossible to know the extent until the concrete is chiselled away.




  • Cracks and reddish/brown rust stains adjacent to the cracked concrete
  • Rust stains leaking out of the concrete
  • Flaking, spalling concrete
  • Bubbling, blistering, plating of concrete render
  • Leaks in overhead concrete surfaces
  • Rusting, exposed reinforcement steel pushing concrete to become loose and break away from the rebar.
  • Other cracks with signs of moisture seeping through the concrete are potential problems.
  • Look out for cracks showing white crystals or efflorescence. As soon as you see the symptoms such as a crack, seepage or a small rust stain, it is best to get an expert in to carry out an assessment.



The typical method of concrete cancer repair follows a process of:


  1. Break out unsound concrete and expose reinforcing steel until sound concrete and clean non-corroded steel reinforcing are found.
  2. Saw cut repair zone perimeter to eliminate feather edges.
  3. The concrete around the reinforcing steel is chiselled away. Prepare substrates including removing any corrosion. Reinstate steel and/or add more as deemed necessary.
  4. After completion of material removal, concrete primers and rust inhibitor to the steel are applied prior to reinstating with a high build shrinkage compensated repair mortar. Formwork may be erected to close the cavity prior to installing the repair products.
  5. For further long-term protection, we also recommend a membrane coating system. Install a heavy-duty modified acrylic membrane in multiple layers as a moisture barrier primer system. The primer system will assist in preventing bubbling or blistering, which is highly likely if the remedial waterproofing application is not performed, which could otherwise affect the durability of the system. Our recommendation is that treatment of concrete cancer should incorporate proper weather/waterproofing membrane or it risks being a temporary solution.
  6. The membrane system is detailed to all penetrations and junctions. The system will be supported by the manufacturer warranty for 10 years and extendable for a further 10 years with a maintenance application.

Concrete cracks can also be repaired using a technique called crack injection where suitable epoxy or polyurethane resins are injected.



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If you have any issues with water ingress, rooftop leaks, leaking balcony, leaking basement, cracking concrete slabs, structural cracks, concrete deterioration, spalling concrete, concrete cancer, deteriorated joints, moisture, seepage, efflorescence, rising damp and/or high-flow active leaks in concrete structures, we would be happy to assist you. You are welcome to contact us with any questions that you may have.

Brisbane office: (07) 3205 1899   


Sydney office: (02) 9346 8308   

Email: [email protected]



Are you interested in finding out more about the various remedial building services we are providing?

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Waterstop Solutions Capability Statement

Waterstop Solutions Capability Statement is now available to download as PDF. (The image is clickable and opens up a link to our Capability Statement). 




Good maintenance begins with a proactive approach to maintain, keep, preserve and protect a building. 

Remember that seepage/water ingress into areas such as balconies, basements, concrete roofs, car parks and retaining walls, should not be ignored – call a remedial waterproofing professional today for an assessment to provide you with the best solution for your situation.

At Waterstop Solutions, we carry out a wide range of remedial works to concrete structures post-construction stage in Brisbane, Gold Coast, Sunshine Coast, Sydney and outlying areas in Queensland and New South Wales.

Equipped with major civil works experience, we can quickly determine the best approach to rectify all seepage and concrete deterioration issues.


It takes licenced remedial waterproofer and leak sealing experts like us at Waterstop Solutions to ensure that the pathways for water to ingress are properly sealed off. A depth of technical knowledge and experience, along with a proud reputation for integrity and reliability, has made Waterstop Solutions the go-to company for many Defect Managers working for major construction companies across Queensland and New South Wales.

We at Waterstop Solutions have the technical and practical expertise to diagnose the source of the leak and will provide you with our recommended solution to achieving an effective, high-quality, long-lasting repair to stop the water ingress with minimal disruption

We believe in and are committed to always delivering high-quality solutions by utilising the right products and techniques for each specific project combined with our industry-leading know-how on tap. We have a large talent pool of specialist leak sealing and concrete repair technicians with Certificate III in construction waterproofing in Queensland and New South Wales that are extensively trained in our systems and project execution methods.

The leadership positions on every Waterstop Solutions project are operated by highly qualified, certified and experienced industry professionals. Our in-house skills and expertise gained from more than 60 years of industry experience provide a full range of high-quality remedial waterproofing and concrete repair works to commercial buildings, civil infrastructures, industrial sites and residential properties. From waterproofing diagnostics, preventative and remediation solutions – All of our waterproofing solutions are quality guaranteed.



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