Concrete like materials have been used by man in their constructions for more than 8500 years. In more modern times (300 BC to 476 AD) Romans used a type of concrete known as opus caementicium and some of those constructions, like Exterior of the Roman Pantheon, finished 128 AD, still stands today. Modern tests conducted on opus caementicium conclude that it is every bit as strong as modern Portland cement.
The biggest difference between the two construction materials comes in the form of tensile strength with the nod going to modern cement due to the practice of reinforcing concrete. Romans didn’t know to reinforce their cement structures with metal and because of this lack of metal, some of their erections, that are already 2000+ years old, will out last most of our modern concrete buildings.
While it is true that our steel reinforced concrete buildings of today are much stronger than the ancient cement structures, it is in fact, the introduction of steel reinforcing in the form of rebar, that greatly reduces the longevity of our modern buildings.
What causes modern concrete structures to prematurely deteriorate you may be wondering? Well the quick answer is water and salt. More precisely, moisture gets into the concrete causing the reinforcing metal to rust and that rust, as it grows, expands and that expansion further breaks down the bonding between the concrete and the rebar.
How to tell if your reinforced concrete is rusting from within? To start with you want to do a visual inspection of your concrete looking for cracks. Any cracks could compromise the bonding between the concrete and the rebar and promote the development of rust.
Should you discover any you are going to want to seal those cracks up with epoxy. For horizontal surfaces, you might even consider a rubber based barrier like they use on underground parking facilities to seal up the concrete.
If you suspect that there is some rusting of the steel reinforcing in your concrete structure, you may need to start chipping the concrete to expose the rebar to check for rusting. If you find some rust then you would need to continue to chip the concrete to expose the rebar until you do not find any more rusted rebar. The process can be long and laborious just to clean up the compromised concrete and internal steel matrix or skeleton or I-beams, joists and or rebar.
This can be a big job and an expensive one that generally requires the aid of rebar specialists like C&J Steel Reinforcing. If you think you may have a problem that needs attention please feel free to contact us and we will try to help guide you in the right direction whether the solution calls for repairs or replacement.
Feature Image by Jean-Christophe_BENOIST