A Century from Now Concrete Will be Nothing But Rubble

FL Keys Old Hwy (4)Photo: road abandoned since 1984 in the Florida Keys

Concrete is an essential part of our infrastructure.

And it’s all falling apart, as Robert Courland’s 2011 book Concrete Planet makes clear.

The Romans built concrete structures that lasted over 2 thousand years.  Ours will last a century — at most.

Courland writes that our infrastructure may last less than a century.  In the ocean, concrete shows signs of decay within 50 years according to Marie Jackson at Lawrence Berkeley National Laboratory.

Despite this, builders, architects, and engineers who know the shortcomings of steel and concrete continue to build structures that will deteriorate.

The problem isn’t the just the concrete; it’s the iron and steel rebar reinforcement inside.  Cracks can be fixed, but when air, moisture, and chemicals seep into reinforced concrete, the rebar rusts, expanding in diameter four or five-fold, which destroys the surrounding concrete.

The repercussions are profound and dangerous — this will eventually destroy nuclear reactor and nearby waste containers (in 2009 the only contender for a nuclear waste disposal site after 40 years of tens of thousands of studies and $10 Billion was Yucca Mountain, but it was put off limits by Energy Secretary Steven Chu in order to get Henry Reid elected).

Other essential infrastructure that will be affected are:  coal and natural gas power plants, buildings, homes, and skyscrapers; roads, bridges, dams, levees, water mains, barges, airport runways, sewage and water treatment plants and pipes, schools, subways, church, canals, corn and grain silos, shipping wharves and piers, tunnels, parking garages and lots, sidewalks, shopping malls, swimming pools, and anything else made of concrete.

Cement is the third largest source of CO2 after autos and coal-fueled power plants. Large amounts of energy are required to produce cement, around 450 grams of coal per 900 grams of cement produced, according to the World Coal Association. Limestone is heated with fossil fuels up to 2,642 degrees Fahrenheit and causes 7% of global carbon dioxide emissions per year.

Courland says that engineers and architects have known about this problem a long time, yet either refuse to admit it or don’t think it matters.  The main theme of this book is that it does matter, as Courland explains in these three excerpts:

1)  The lifespan of concrete is not only shorter than masonry, it “is probably less than that of wood…We have built a disposable world using a short-lived material, the manufacture of which generates millions of tons of greenhouse gases.”

2)  “Even more troubling is that all this steel-reinforced concrete that we use for building our roads, buildings, bridges, sewer pipes, and sidewalks is ultimately expendable, so we will have to keep rebuilding them every couple of generations, adding more pollution and expense for our descendants to bear.  Most of the concrete structures built at the beginning of the 20th century have begun falling apart, and most will be, or already have been, demolished”.

3) The world we have built over the last century is decaying at an alarming rate. Our infrastructure is especially terrible:

  • 1 in 4 bridges are either structurally deficient or structurally obsolete
  • The service life of most reinforced concrete highway bridges is 50 years, and their average age is 42 years….
  • Besides our crumbling highway system, the reinforced concrete used for our water conduits, sewer pipes, water-treatment plants, and pumping stations is also disintegrating.  The chemicals and bacteria in sewage make it almost as corrosive as seawater, reducing the life span of the reinforced concrete used in these systems to 50 years of less.”

I’m sure the American Society of Civil Engineers (ASCE) would agree. Below is their 2009 report card for America’s infrastructure (all of these use at least some, if not a lot, of concrete).

  • C+ Solid Waste
  • C Bridges
  • C- Public Parks and Recreation, Rail
  • D+ Energy
  • D Aviation, Dams, Hazardous Waste, Schools, Transit
  • D- Drinking Water, Inland Waterways, Levees, Roads, Wastewater

Their 2013 report card will state we need over 3 trillion to fix this. But ASCE says nothing about the short life of concrete anywhere on their website, let alone demand that future projects be built to last.  The ASCE 2013 report card didn’t mention that we need to build millennia-long lasting concrete buildings, roads, bridges, dams, schools, drinking water pipes and facilities, and levees in the future.

We know there’s a problem.  Scientists have started to try to figure out how to make concrete last longer since 2007.  Yet there’s no pressure to make concrete last longer, because it’s cheaper to do it the wrong way, especially in a time of tight credit.  To do it right would cost more up front, but the financial system only cares about immediate gain, not the payback is tens of trillions of dollars in saved future costs.

On top of that, there’s no demand from the public, journalists, engineers, or architects.  There has not been any outcry since this book was published to build with long-lasting concrete in the future.

Alan Weisman’s in his book, “The World Without Us”, writes of places abandoned by people, such as Chernobyl.  It doesn’t take long for vegetation to crack and take over buildings, roads, and other concrete structures.  For example, consider what knotweed can do:

Knotweed can pierce tarmac and crack concrete foundations, causing serious damage to infrastructure, and grow up to a meter per month. In winter the underground rhizome survives and can grow as much as 14 meters long and 3 meters deep. The rhizome can even survive burial by volcanic lava and send up rock-piercing shoots when the surface cools. “A plant like that will laugh at concrete foundations,” says Mike Clough of Japanese Knotweed Solutions in Manchester, UK (Pain).

There is a program to make better concrete at the National Institute of Standards & Technology Engineering Laboratory. One programs is researching how to prevent concrete from cracking in a program called REACT: Reducing Early-Age Cracking Today.  In 2007, the National Infrastructure Improvement Act, to establish a National Commission on the Infrastructure of the United States, passed in the Senate but failed in the House.

Update 2013: No fix yet to make concrete last for millennia.  The fixes below are both expensive and temporary, since once the capsules are released they’ve shot their wad:

  1. Using bacteria that emit limestone to self-heal concrete by mixing tiny capsules of these bacteria within concrete that multiply when a crack breaks the capsule open.  The bacteria also use up oxygen that would have corroded the steel bars.  Whether this can be done or not is not clear since concrete is a very hostile place for bacteria due to high alkalinity, and as the concrete cures, it’s likely to crush many of the microcapsules.
  2. Filling the concrete with polymer microcapsules that break open and turn into a water-resistant solid when exposed to sunlight, filling in the crack.
  3. Add spores of bacteria that can last for 50 years and food for them so that when concrete cracks, they form a glue to fix it.  This is a one-time-only fix though.
  4. Coat rebar to protect it from rust.  This special rebar takes longer to rust, but it is very expensive and will eventually rust, often within 20 years, and especially if it is scratched or dinged at any point in its lifecycle.

There may not be a way to make concrete last

It’s too expensive to ship gravel, crushed stone, and sand very far, so concrete is made from local ingredients, which are often less than ideal, and which will vary infinitely in their properties both locally and across the nation.  Steel also varies in what alloys were used, how strong and corrodable it is, and asphaltic concrete will vary depending on the crude oil source of the bitumen.  It’s often mentioned that Roman concrete lasted because of the use of volcanic ash, perhaps the Romans just lucked out with good local materials.  And Rome didn’t have to deal with the freeze-thaw cycle, rust from steel rebar, heavy trucks, and other modern insults.  It simply may be impossible to make concrete last over a century given the endless combinations of chemistries embodied in the unique mixes of local stones.

Peak Energy and Concrete

Look out your window — all the homes and buildings you see are built on concrete foundations.  The roads, streets, the bridges are nothing but an illusion.

I can’t get some of some of the verses from the Talking Heads Nothing But Flowers out of my head:

There was a factory
Now there are mountains and rivers
There was a shopping mall
Now it’s all covered with flowers
The highways and cars
Were sacrificed for agriculture
Once there were parking lots
Now it’s a peaceful oasis
This was a Pizza Hut
Now it’s all covered with daisies
And as things fell apart
Nobody paid much attention

Why waste our remaining energy  to make concrete? At this point it seems crazy to build projects with short-term concrete we KNOW will only last for decades.  Once we stop repairing our concrete (and cement) structures, they will quickly fall apart.

Why try to rebuild our infrastructure and create vastly more greenhouse gases?

Our descendants won’t be driving much.  They’ll probably wish we had converted most of the roads to farmland, which will take centuries even after the cement is gone for the soil to recover — why not start now?  Stop maintaining roads in the national forests, rural areas, and wherever else it makes sense –let them return to gravel, jackhammer and remove the rubble while we still have the energy to do so.

De-paving and de-damming would also restore streams, fisheries, wetlands, and ecosystems for future generations.

Future generations eventually won’t have the energy to maintain, repair, or rebuild very many concrete structures in a wood energy based civilization.  Courland says it takes one cord (4 x 4 x 8 feet) of wood to make 1 cubic yard of lime.

Those of you downstream from large dams might be interested to know that Courland says they are still “undergoing the curing process, thus forestalling corrosion. It will be interesting for our descendants to discover whether the tremendous weight of these dams will continue to put off the rebar’s corrosion expansion”.

Failing dams are a double tragedy, since electricity from hydro-power will be especially valuable as one of the few (reliable) energy sources in the future.

James Howard Kunstler writes that surburbia will be seen as one of the greatest wastes of energy and resources in the future.  It goes way beyond that. Our infrastructure is one-third and one-half concrete.  It’s all a waste.

A wasteland. There will be absurd amounts of concrete rubble — what the hell are people in the future going to do with 300 billion tons of concrete? Build sheep fences?

Alice Friedemann

Pain, Stephanie. 3 July 2014. How to kill knotweed: Let slip the bugs of war. NewScientist.


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3 Responses to A Century from Now Concrete Will be Nothing But Rubble

  1. Geo says:

    very interesting article. I knew that we are going to have problems maintaining what we’ve built in an energy-scarce era, but not that modern concrete will fall apart so quickly. What a colossal malinvestment — not just in the USA, but China, too…

  2. doomphd says:

    well Alice, the easy answer is there may not be a lot of people around in the future to build or maintain much of anything. A great book and TV program on this topic is “The World Without Us” by Alan Weisman.

    The underlying assumption or conceit of modern civilization is there will always be abundant cheap energy and a stable climate to sustain it. A corollary is no more world wars, especially nuclear ones. Unless a new form of abundant cheap energy is found soon, the maintenance of infrastucture will lapse as the structure of modern civilization itself disentigrates. Even if new form of energy is found and rapidly deployed, the climate may have been permanently destabilized by past fossil fuel burning and the very cement manufacture we hope to maintain. It’s a predicament humans embarked upon a few thousand years ago and appears to be rapidly nearing its end game.

  3. Rick Larson says:

    News to me. Thanks much!