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How to avoid Salt Water Corrosion Within Reinforced Concrete

16 March 2016

Ever wondered how to avoid salt water corrosion, or also called concrete cancer, within reinforced concrete? These issues have weakened structures for decades and fixing it would cost a fortune. How to avoid concrete cancer is not a mystery any longer and the solution is simple, though first we need to understand the issue.

Cause of Corrosion Within Reinforced Concrete

Corrosion of reinforcing steel and other embedded metals is the leading cause of deterioration in concrete, as some bridge piles and piers have only lasted 10 years in a saltwater environment. The corrosive effect of the seawater is a problem engineers and architects have been faced with for a long time. The the chloride ions in salt water migrate to the embedded steel and cause corrosion and subsequent spalling of the concrete.

Concrete contains an alkaline environment that provides some protection against corrosion. The reinforcing steel in the concrete will react with the concrete and form a film that protects the steel. This is where salt water works against that process. The chloride and sulfate ions will weaken that film as the water soaks into the concrete, and once the film is breached, then the corrosion process begins to work on the steel itself.

Since concrete is a permeable material, oxygen and humidity can be present at the point the salt water has come into contact with the film. This is when the corrosion process of the steel will begin. When steel corrodes, the steel in form of rust will expand and occupy a greater volume than the steel itself, which creates stress in the concrete and can eventually cause cracking, delamination and spalling.

To stop water reaching inside the concrete structure a barrier between concrete and the salt water is needed, which stop water, chlorides and oxygen from reaching the inner of the concrete structure. Our research team at Tech-Dry developed a deep penetrating sealer to stop the concrete from corroding. Once applied Tech-Dry’s Solid Silane, the concrete will react with the silane cream. The silicone components in the cream will deeply penetrate into the concrete and will render the substrate water respellent.

Solution

Solid Silane contains 80% n-octiyltriethoxysilane, a form of a water-based thixotropic cream which resists water and chloride ion ingress into the concrete. Due to the formulation being water-based, it is an extremely environmentally friendly solution with zero VOC content.

This silane solution is a new concept that overcomes the problems associated with liquid silanes, such as isobutyltriethoxysilane. Due to its thick, cream like concistency Solid Silane can be applied to overhead and vertical surfaces without run off. Unlike liquid silanes, one coat of Solid Silane is generally enough to achieve a similar depth of penetration as several coats of liquid silane, as the cream will not run off and has time to soak into the within the concrete.

Solid Silane has been thoroughly tested and has proven its effectivenes. The official tests were conducted by Taywood Engineering and the Victoria University of Technology (Test Reports can be requested).

By now the product has been used on several major projects, as for example the Brisbane Port, where the Solid Silane cream was applied on the whole wharf area, the Tsing Ma Bridge in Hong Kong, the Gateway Bridge in Queensland and numerous other projects

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