3 Feb 2014

London Bridges Falling Down Carbonation and Concrete Infrastructure

I have been planning, or considering, writing an article about the carbonation of concrete. I have been reading documents found on the Internet, I have been looking closer at our own lab reports that tested for the carbonation of concrete.  But I hadn’t put pen to paper until I noticed another news article about a concrete bridge, or overpass, that had shed a piece of concrete onto the hood of an under passing car. Apparently no one was hurt! (Under garments may have been damaged!)

What I have read about concrete carbonation seems to directly relate to pieces of concrete breaking away from a structure. Apparently there is a chemical reaction that takes place when pollution carrying moisture is absorbed into concrete. This reaction is acidic, and if the concrete has imbedded steel rebar, or steel re-enforcing components, this metal will start to return to its “ore” state. In other words, the steel will rust and, rusted steel takes more room than non-rusted steel.  Rusted steel will take the increased space with enough force to break the concrete that the steel is within.

The United States Environmental Protection Agency and Environment Canada describe acid rain as a term generally used to describe the wet or dry depositing of material from the atmosphere containing higher than normal amounts of nitric and sulfuric acids.

So acid rain is a method of delivering these pollutants to be channeled into concrete. I’m not sure if road and bridge builders are employing any methods of preventing moisture, and therefore acid rain, from being absorbed into the concrete. If they are, I would be rethinking how well their methods work.

It is actually quite simple to make concrete waterproof and prevent the damage that can come with carbonation. One application of Seal-It Concrete Sealant will convert concrete into a waterproof, carbon proof substrate that will not require future treatment.

You do not have to take my word, take a look at the last page of this independent Lab report on carbonation. The second paragraph, or item, describes 4 sample concrete pieces. Two untreated, the labs way of saying Seal-It Concrete Sealant has not been applied, and two converted, the labs way of saying Seal-It has been applied. The untreated specimens are shown to have allowed carbonation to have penetrated to a depth of more than half an inch. The converted specimens, or those treated with Seal-It, are found to have zero depth penetration of carbonation.

Carbonation is destructive to concrete. Rain and moisture carry components of carbonation into concrete. Seal-It Concrete Sealant blocks rain and moisture from entering concrete. Seal-It Concrete Sealant protects concrete from carbonation destruction.