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concrete corrosion

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3 Reasons Why Corrosion Protection is the Sustainable Way for Buildings - Part 1

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In the UAE and in the region in general, the geology of our coastal cities in the Middle East require the use of pile or raft slab foundations built from reinforced concrete to be used. These very large underground structures are typically constructed in the water table. Waterproofing attempts typically fail to stop all water ingress, and the basements are often times leaky and inundated with groundwater or significant leaks. Sometimes I have seen entire basements flooded almost to the ceiling of the basement.

 The question we should be asking ourselves is, once the leaks are plugged and the water pumped out, do we still have a problem or are we in the clear?

Do we still have a problem or are we in the clear?

To be sure this is not a one liner. Let’s consider the situation. The floor is made from reinforced concrete. It is now fully laden with chlorides, even after removing all the offending water...

We certainly can’t see the chlorides, but they are there – unless you have somehow managed to miraculously to suction out the chlorides from within the concrete matrix.

With the chlorides present in party like quantities, you now have the main recipe for corrosion;

  • Salt

  • Water (moisture in the concrete)

  • Oxygen

Unfortunately for corrosion engineers, and fortunately for owners, the initiation of corrosion is not something that you can see. If the waterproofing fails…poof….and there is a leak

If corrosion begins….there is only silence. You won’t hear anything, you won’t see anything, at least not until it is too late.

So while the owner goes about renting out his building and counting his rental income, the corrosion reaction also goes about eating away at his steel foundation.

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What are the owner’s options?

 There are a plethora of remedies available. All claim to stop this phenomenon in some way or form. But to be honest there is only one method, which will in effect freeze the corrosion in its tracks. Cathodic Protection. In the next part of this blog, we discuss in more detail the corrosion problem, cathodic protection and sustainability.

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EARLY CORROSION DETECTION TO AVOID COSTLY REPAIRS OF CONCRETE STRUCTURES

The protection of assets from corrosion is a key commercial, safety and environmental issue.

Deterioration of concrete structures can become a challenge for the owners of structures such as bridges, walkways, high rise buildings, etc. It is important to identify these defects on time and plan appropriate repair strategies. Concrete deterioration can occur through scaling, disintegration, erosion, corrosion of reinforcement, delamination, spalling, alkali-aggregate reactions, and cracking of concrete. Moreover, corrosion of reinforced steel is the main cause in modern concretes.

Successful contractors understand the importance of adding value to their clients' assets/structures. One of the best ways to do this is to offer additional services that provide a cost-effective benefit to the client. Contractors can provide value added service to their clients through the application of cathodic protection. Cathodic protection system stops the corrosion cycle in concrete by utilizing an electrical current. It can be an add-on service for the concrete contractor and a cost-effective benefit to the client.

How does cathodic protection work?

In the simplest terms, a small DC electrical current is discharged off of an anode and flows through the concrete to the reinforcing steel. This protective current prevents corrosion from occurring. A small power supply unit converts AC power available at the site to DC power to provide the negative charge, which is used to arrest the natural corrosion process. Typically these systems use very little power -- not much more than a conventional 120 Watt electric light bulb. The contractor has a wide range of decorative top coats available to finish the process while meeting the aesthetic requirements of the project. For more than 20 years, this proven technology has been employed successfully on numerous installations in coastal environments.

Contractors should be encouraging their clients to consider cathodic protection when major repair projects are undertaken. The first reason is the most important -- quite simply, cathodic protection stops the repair cycle by preventing further corrosion. When the client/owner completes a major concrete repair only to find that more corrosion is occurring just a few years later, there is an unhappy client eager to blame the initial repair contractor. Cathodic protection stops future corrosion which in turn stops the vicious restoration cycle.

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Culprits That Caused Miami Bridge Corrosion

#corrosion #Infrastructure #bridge

3 Culprits That Caused Miami Bridge Corrosion

Jet Skis, waverunners and other personal watercraft shooting salt water up at the underside of the MacArthur Causeway have caused extensive corrosion on one end of the bridge, necessitating repairs to beams and columns. It's also time to replace the top three inches of concrete on the bridge's surface.

The bridge connects the city of Miami to the barrier island of Miami Beach.

Residents and commuters of the notoriously traffic-jammed region should brace themselves for a long stretch of headaches on the main causeway connecting South Beach to mainland Miami.

The Miami Herald reports the Florida Department of Transportation began a two-year, $12.9 million rehabilitation project on the corrosion of the bridge in June 2018.

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Reference: https://www.nbcmiami.com/news/local/Waverunners-Jet-Skis-to-Blame-in-Miami-Bridge-Corrosion-488207961.html

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