Concrete is 2,000 years old or more. One example of an ancient structure still standing is the Roman Pantheon from 128 AD, built in the reign of the emperor Hadrian. There are actual dates stamped into bricks in this structure. If you haven’t traveled to Rome, you’ve probably seen the pantheon in many films made in Rome. It’s one of the most popular tourist sites.
The pantheon is visited by millions of travelers every year, a testament to the durability and strength of concrete. No one would be allowed inside or within a wide radius of the building if it were unsafe. Concrete is used for dams holding back vast amounts of water, which means it is extremely strong when made to be. The Hoover Dam and the Panama Canal are examples of this. There are hundred-year old structures that stand without problems to this day.
Smeaton’s Tower, originally a lighthouse, in Plymouth, England, was built in 1759, and the base still stands in the water because it was too sturdy to dismantle. The lighthouse was moved in 1882, or it would probably still be there intact. The base is more than 250 years old, upholding the strength of old concrete, literally.
Why does age matter? It matters when a home needs a dry basement while people live in it. It also matters when a building is meant to last a long time as a courthouse or library. Even though our society tends to tear down and rebuild, there is much more concern now about recycling and re-use to prevent waste and reduce trash dumps.
Concrete can be recycled, if it is not holding up a bridge or other mammoth structure. It is crunched into gravel for road bases, also made out of concrete, and metal cages filled with crushed concrete can provide support for retaining walls. So, old concrete is good standing or crushed. Even the metal rebar is extracted and reused when a concrete structure is torn down.
Concrete roads withstand decades of use from huge semi-trucks and giant RVs as well as millions of cars every year. Concrete-carrying trucks are quite heavy, logically. That’s the staying power of concrete. It tends not to burn, so fire is not a threat to concrete and another reason it lasts. London would not have been so badly destroyed in the 1600s if it had used more concrete: just a thought.