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Spalling concrete repair – Specialist remedial solution

Concrete repair of spalling concrete suspended slab by Waterstop Solutions

Spalling concrete repair – Specialist remedial solution

Are there any consequences of untreated spalling concrete caused by corrosion of embedded steel reinforcements?

loose pieces of concrete fallen down from the ceiling - Waterstop Solutions

Image: Large, loose pieces of concrete fell down from the suspended slab, exposing rusting reinforcing bars. No one was injured, fortunately.

Our client had discovered loose pieces of concrete in his garage which had fallen down from the ceiling. The corroding steel had expanded many times its original size, causing the concrete to crack and eventually break loose. Thankfully no one was hurt by the falling pieces of concrete.

He engaged Waterstop Solutions because he was looking for a quality remedial solution to reinstate the integrity of the concrete slab with the aim to help prolong its service life.

Concrete + steel = Great partners in the built environment

When concrete is reinforced with steel rods and the steel is embedded with adequate and high-quality concrete, we achieve a composite material that not only resists compression and some tensile stress, but the passive film on the surface of the steel formed by the concrete’s high pH (alkalinity) acts as a protective shield that prevents or minimises corrosion.

A reduction of the concrete’s pH by carbonation or the ingress of chlorides (salt) are the most common causes of concrete deterioration as it causes the steel’s passive film to degrade. Rust begins to form on the unprotected steel. The build-up of rust causes tensile stresses as it grows in thickness. The pressure causes the concrete to form cracks near the steel, which will lead to more extensive cracking as the rust builds up until the concrete starts to break away and exposes the corroded reinforcing steel. This is commonly called concrete spalling or “concrete cancer”.  This can affect the compressive strength and thereby reduce the bearing capacity of the structure and shorten its service life if left untreated.

Corrosion of steel-reinforced concrete is most commonly found in columns, beams and precast concrete. It can often be linked back to a lack of adequate concrete cover, and/or poor concrete quality allowing moisture-borne contamination (chlorides, sulphates, carbonates, etc.) to access the steel via cracks.

Three conditions must exist for reinforcing steel to corrode:

• The passivation of the steel must have been destroyed by chlorides or by carbonation
• The presence of moisture as an electrolyte
• The presence of oxygen


𝗕𝗼𝗼𝗸 𝗮𝗻 𝗶𝗻𝘀𝗽𝗲𝗰𝘁𝗶𝗼𝗻 𝘄𝗶𝘁𝗵 𝗼𝗻𝗲 𝗼𝗳 𝗼𝘂𝗿 𝗲𝘅𝗽𝗲𝗿𝗶𝗲𝗻𝗰𝗲𝗱 𝗶𝗻𝘀𝗽𝗲𝗰𝘁𝗼𝗿𝘀 𝘁𝗼𝗱𝗮𝘆!

Have you noticed any signs of deteriorating concrete such as spalling, cracks and rust stains in your building?
Waterstop Solutions Pty Ltd inspectors are equipped with extensive industry knowledge and the latest in non-invasive inspection technologies. Our thorough site assessment and diagnosis process provides our clients with industry-leading expert advice.
In addition to our regular inspection service, we can provide audits of multi-storey concrete buildings.
The audit consists of a defect information list of items classed in priorities from P1 to P4, and their repair types. Ask us about how to secure a booking for this additional service.


Waterstop Solutions is one of the leading companies in our areas of expertise of fixing leaking buildings and concrete structures.

QBCC Licence Number 1162603 – Classes: Concreting and Waterproofing


If you have any issues with leaking balcony, water ingress, cracking concrete slabs, structural cracks, concrete deterioration, 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?

Please click on the image below to download Waterstop Solutions Capability Statement

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.


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