Basics of Corrosion in Reinforced Concrete

From JPCL, August 2015

by Fred Goodwin and Frank Apicella, BASF Construction Chemicals

Corrosion in reinforced concrete has been an issue since it was first introduced and will be an issue for the foreseeable future. The authors discuss sound practices to mitigate corrosion before significant deterioration occurs....
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Tagged categories: Coating Materials; Concrete; Concrete defects; Corrosion protection; Fred Goodwin

Comment from Manoj K. Shah, (9/9/2015, 3:09 AM)

useful informations to create awareness....keep it up.


Comment from Joe Miller, (9/9/2015, 3:52 PM)

Fred and Frank, Pretty good scope to your article. There are several things mentioned in it that do not line up with the facts however. Concrete in its earliest iteration, for example, was called Roman Concrete. The mix design was very different from what we call concrete today. Roman concrete was a very durable, long lasting mix. I have personally seen and touched Roman aqueducts in Spain that were built some 2,000 years ago and are still functiong. The small iron bits used to hold the roman concrete sections in place are corroding but they are still holding in place. There are many sites in the former Roman Empire that have Roman concrete still doing its job. Segovia, Seville, Budapest, Lisbon, etc. When so-called Portland cement was invented and then steel reinforcement used to create a composite then the corrosion problems became evident----but only after many, many years of service. One of the early adopters of Portland Cement concrete was the Third Reich who mixed and placed more of it than anyone thought possible at that time. They claimed it would last 1,000 years. I think to link the 2 concrete together is mis-leading and creates a false impression that our current iteration of Portland cement concrete will last a 1,000 years. And we all know it won't. On a recent tour of Germany we found massive rebuilding of the Autobahn roadways, bridges and superstructures. Since Portland Cement concrete lasts only a brief period of time compared to the design life expectations I humbly suggest we quit misleading the world into thinking it will. And start using every means we have to help it last as long as possible including admixtures, protective coatings on the steel (that work), liquid crystalline penetrating surface treatments and various deck, column and beam coatings as well as CP systems---and anything else I forgot to mention. We invest incredible sums on our concrete infrastructure. We must extend its useful service life as long as we can. More next time. Thanks, Joe Miller/President/www.Direct2Contractors.com


Comment from Joe Miller, (9/10/2015, 3:44 PM)

Fred and Frank, Your article correctly points out that the rusting of the steel reinforcement occurs when they begin to corrode. It might be useful to mention that the force of this expansion easily exceeds the tensile strength of most Portland cement concrete mix designs. High Strength Portland cement concrete refers to the compressive strength of the mix design. Modern mix designs as you know can be quite high, above say 10,000 psi. But the tensile strength of even such so-called high-strength concrete is still too low to resist the expansive forces of the rusting steel. Yet engineers persist in using it justifying their choices for cost reasons. A valid cost-benefit analysis would I think easily prove these choices as less than ideal. Likewise, the use of preventative treatments are dismissed, again for invalid cost reasons----in my opinion. Hope this also helps. Thanks, Joe Miller/President/www.direct2contractors.com. An eCommerce website helping to change the way Contractors can access the lowest prices and freight rates with shipments direct from the manufacturing plants to them.


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