America’s trillion-dollar concrete bill is coming due

Concrete construction no longer lasts thousands of years, like the Pantheon in Rome. Instead, its lifespan is roughly 50-100 years, thanks to the way in which modern concrete is reinforced.

Why it matters: That means a multi-trillion-dollar bill is coming due right around now, in the form of concrete construction that needs noisy, dirty, expensive repair.

• The collapse of a residential tower in Surfside, Florida, is a stark reminder of how catastrophically concrete can fail.
• Just as the collapse of the Morandi Bridge in Genoa caused Italy to start paying much more attention to remedial infrastructure projects, the Surfside tragedy might help focus America on the urgent need to fix buildings that are nearing the end of their initial lifespan.

The big picture: As Robert Courland explains in "Concrete Planet," modern concrete is poured around steel rebar, which gives it tensile strength. But tiny cracks — found in all concrete — cause water to start rusting the steel, which then expands, cracking the concrete.

• Photos of the Surfside basement taken before the collapse show steel rebar breaking all the way through the concrete to the point at which it is fully exposed to the salty and humid Florida air.

By the numbers: One of the most famous concrete buildings in America, Frank Lloyd Wright's Fallingwater, cost $155,000 to build in 1936 — about $2 million in 2001 dollars. The cost of repairs in 2001 came to $11.5 million.

• Similarly, repairs to Wright's concrete Unity Temple are estimated at roughly 20 times the original construction costs, even after adjusting for inflation.

How it works: Once rebar starts corroding, the standard fix involves jackhammering the concrete to expose the steel, brushing the steel to remove the rust, reinforcing the rebar as necessary, and then covering it all back up again with carefully color-matched new concrete.

• That labor-intensive extreme noise and dust is actually the green, environmentally sensitive solution. The only alternative is demolition and replacement with an entirely new building — something that involves a much greater carbon footprint.

Between the lines: Because concrete fails from the inside out, damage can be hard to detect. And because concrete looks so solid and impregnable, necessary maintenance is often skipped, causing massive bills later on.

• Local governments are in charge of ensuring building safety, but their willingness and ability to do so varies widely. The owners and residents of concrete buildings often try very hard not to think about corrosion, just because the costs of fixing it are so enormous.

The bottom line: The amount of money needed to fix existing infrastructure (nearly all of which is concrete, in one way or another) stands at roughly $6 trillion, according to the American Society of Civil Engineers. That number does not include homes, offices and other private buildings.

• If you live in a concrete building that's more than 40 or 50 years old, it's an extremely good idea to check carefully on just how well it's been maintained, lest you find yourself with an unexpected seven-figure repair bill — or worse.

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