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 the buildings and monuments we build may last less than a century, 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, and ultimately destroys the building, road, bridge, dam, levee, home, airport runway, sewage and water pipes, school, canal, power plants, grain elevators, shipping piers, tunnels, and so on.
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.?? Cement is the third largest source of CO2 after autos and coal-fueled power plants.? The World Coal Association states that ?Coal is used as an energy source in cement production. Large amounts of energy are required to produce cement. Kilns usually burn coal in the form of powder and consume around 450g of coal for about 900g of cement produced?.
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 comes out March 19.? I?ll be watching to see if they even 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, we know how to fix it (the last chapter explains how to make long-lasting concrete), and yet there?s no pressure to do it, because it?s cheaper to do it the wrong way, especially in a time of tight credit.?? To do it right, it costs a bit more up front, but the payback is tens of trillions of dollars in saved future costs. I predict Capitalism?s? short-term? focus will prevent long-lasting concrete projects from coming to fruition.
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 that I can find.
Well, have only been two attempts to do something that I could find:
- A bill that passed in the Senate (S.775) but failed in the House: The National Infrastructure Improvement Act, to establish a National Commission on the Infrastructure of the United States
- The National Institute of Standards and Technology?s Engineering Laboratory has started to fund research to prevent concrete from cracking in a program called REACT: Reducing Early-Age Cracking Today.
Peak Energy and Concrete
It will take a tremendous amount of energy to replace and/or fix our concrete infrastructure, energy that will be less and less available.? Why waste our remaining energy and create vastly more greenhouse gas to make concrete, unless it will be built to last thousands of years like Roman Concrete?
Our descendants won?t be driving everywhere, in fact, they?ll probably wish they could convert the pavement 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 and eventually fade away.
Perhaps we should even consider DE-paving and DE-damming to restore streams, fisheries, wetlands, and ecosystems for future generations.
We should convert some roads to railways while we still have energy to spend, since trains are around seven times more efficient than trucks.
At this point it seems crazy to build projects with short-term concrete we KNOW will only last for decades.
Eventually buildings over 5 stories tall will be of little use ? why keep building skyscrapers?
Future generations won?t able to build, let alone repair and maintain what we construct.? Once we stop maintaining our concrete (and cement) structures, they will quickly fall apart.
We just won?t have the energy to build and maintain many concrete structures in a wood-based civilization.? Consider all the wood it used to take for a limestone kiln to make 1 cubic yard of lime: a dozen cords of wood (a cord is 4? x 4? x 8).
Another example Courland cites (page 139): Since the Mayans ?used 20 full-grown pine trees to create just 1 cubic meter of lime, the amount of deforestation caused by the need for farmland, plaster, and stucco probably tipped the environmental balance deep in the red?.
I wonder how many trees would be needed to build the 27.1 million cubic meter Three Gorges Dam in China?? ?I suspect even deforesting the earth wouldn?t be enough.
And those of you downstream from the Hoover and other large dams might be interested to know that these 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? (page 327).
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.
And what the hell are the people in the future going to do with all this concrete ? build sheep fences?
Alice Friedemann
Energy Skeptic
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