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How to Fix Concrete Cancer

What concrete cancer is, and the waterproofing solutions to fix or prevent concrete cancer.

What is Concrete Cancer?

Concrete cancer is the breakdown of a building’s concrete, specifically in areas that surround internal steel reinforcements.

Concrete cancer occurs when water makes contact with the structural steel reinforcement bars and causes rust. The steel bars then forcibly expand and deform, breaking apart the concrete that surrounds them. The concrete ‘spalls’, i.e. breaks apart and falls away in chunks.

Buildings are often required to ‘encase’ the steel rebar with specific types and depths of concrete. This serves to shield the steel from the elements, which may include varying levels of rain and/or salt (if near the ocean). However, concrete, no matter how thick or what type, remains a porous substrate. Water likely will eventually soak through to the steel within, and concrete cancer will then occur in time. However, there is a way to prevent or treat it before significant damage is done.

How to Repair and Prevent Concrete Cancer

Concrete cancer, and other similar problems like efflorescence, can be treated or prevented. Chemical water repellency can be added to the concrete surface itself by means of applying Resistain, a concrete waterproofing sealer.

Resistain is an advanced liquid waterproofing sealer that is applied to concrete surfaces using a brush, roller or spray. It soaks into the concrete to a depth of 10mm, binds with the structure of the concrete in a molecular level and forms a water-repellent barrier. Once Resistain is applied, the concrete floor itself will repel water and salt. This protects the surface from all forms of water damage, including concrete cancer, efflorescence, mould, algae, discolouration and weather-based erosion.

Resistain will also be applied as stain resistant floor sealer that reduce staining by various causes, and will also provide oil repellent coating.

How to Treat a Surface Using Resistain

A thorough guide to waterproofing concrete and other surfaces is available here.


Preparation equipment:

  • Concrete cleaning equipment
  • Concrete gap-filling or crack repair equipment if needed.

Application equipment:

  • Resistain penetrating sealer
  • Brush, roller or spray for applying Resistain
  • Cloths or rags to wipe up excess Resistain.


Prepare the surface to be treated by cleaning any dirt, grime, mould or foreign matter from the concrete.

If there are any gaps in the surface, these need to be repaired so the concrete surface is unbroken before applying Resistain.

Using your preferred application tool, apply an even coat of Resistain to the surface. The surface should have a mirror-like appearance.

After the first coat is absorbed into the concrete, apply a second coat of concrete sealer.

10 minutes after the second coat, wipe away any remaining liquid that will not soak in. If the surface is still soaking in Resistain, another coat can be applied as concrete is highly porous.

The surface will be water-repellent as soon as the treatment soaks in, however the full curing process will take up to a week.

Use isopropanol or a dry cloth to clean Resistain off the equipment or other non-masonry surfaces.


Resistain will maintain the surface for a minimum of 15 years. It can be reapplied at any time.

Surfaces already experiencing water damage, and surfaces which are as yet undamaged, can be treated. It is recommended to use Resistain as a preventative measure.

Resistain is one of the best sealers available for stain proofing, waterproofing and oil repellency. It works equally well as a concrete or stone sealer, and is ideal as a driveway sealer. See the Resistain concrete sealer range on our website where you can order online.

Concrete Protection Company
Concrete Protection Company
Concrete Protection Company (CPC) is an Australian-owned and operated company which specialises in high-quality solutions in masonry protection. Our objective is to offer high-quality, reliable, long-lasting and easy to use products to help maintain your masonry surfaces.

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