I recently listened to an extremely interesting Stanford entrepreneurial podcast by Brent Constantz of Calera, who definitely has a planet-changing vision. You can listen here.
Brent and I share the same goals: to use technology to reduce the carbon footprint of the world’s construction industry.
According to Brent, production of Portland cement (a component of concrete) is the 3rd largest source of anthropogenic CO2, at about 3 billion tons annually.
Cement is a trillion dollar market, but the story doesn’t stop there: standard reinforced concrete is about 20% cement, and 80% aggregate. This aggregate is often composed of limestone & carbonate rock, mined from the earth’s lithosphere, often in unsustainable & environmentally-unfriendly open pit mines. Calcinization of limestone requires a good bit of energy and release of CO2, which is often drawn from coal power!
At the same time, standard reinforced concrete & masonry construction is the most prevalent method of construction worldwide, and often the only accepted way to reliably provide fire & disaster-resistant buildings.
Brent’s company, Calera, aims to directly affect the amount of carbon dioxide produced by concrete construction through innovative catalysts and chemistry, recycling carbon dioxide into their replacement for Portland cement. From the Calera website: “Sequestering CO2 in the Built Environment“.
Also, Brent doesn’t think cap and trade is a viable approach to dealing with anthropogenic CO2 production. Rather, he aims to promote green economies by financially engaging business which is both green & and prosperous.
How does Ferrocement fit into this?
Like Brent, I’m concerned about the future of our planet, and the world we leave to our children. I’ve always designed “green”: with thought toward the environment & energy usage, even before it was fashionable – hence my interest in Ferrocement!
Ferrocement is a construction method which uses considerably less material (both steel & cement) than standard reinforced concrete. Widespread use of Ferrocement could significantly lower the carbon footprint of new construction, by approximately 80%. Yes, that’s 80% less Carbon, and no, I’m not kidding!
I’ve spoken about this elsewhere, on the Ferrocement.net forums.
Except for wooden residential buildings in places like the USA, England, Canada and Scandinavian countries, most permanent construction worldwide is made of masonry and concrete, and for good reasons. Primarily, wood is often not available or durable enough to provide adequate built space in most climates.
Although concrete was popularized by the Romans, reinforced concrete was not invented until the mid-1800’s in France. You’ve seen reinforced concrete: it’s formed by wiring steel reinforcing bars into a cage-like configuration, placing this in a wooden formwork, and then pouring a sand, gravel, cement, and water mixture (concrete) into the formwork. The formwork is removed when the concrete has hardened. Concrete is brittle and relatively weak in tension (pulling), yet very strong in compression (pushing). Generally, there is much more of the concrete mixture than steel in the resulting structure. So concrete and masonry buildings are on the brittle end of the scale, subject to cracking, breaking, and falling apart under duress – such as seismic activity.
About the same time, another iteration of concrete was also invented: ferrocement, literally: “iron-cement.” See my blog post for a quick history of Ferrocement.
In contrast with reinforced concrete, ferrocement is usually composed of a thin steel network with the concrete mixture tightly packed around the steel. Ferrocement acts as an extremely strong, flexible, and supple stress-skin structure: the tensile (pulling) strength of steel is balanced with the compression (pushing) strength of concrete.
Although ferrocement uses much less concrete material to cover space than reinforced concrete, it is not widely used because of the expense of creating curved formwork, and of packing the cement material around the steel matrix. This is where my invention comes in: the am-cor System. We’ve developed a method of prefabricating & panelizing Ferrocement forms, so a building can go up extremely quickly, and importantly, the total construction cost is considerably less than that of standard reinforced concrete!
The carbon savings are simple: where a reinforced masonry and concrete building would require 8” (20cm) and 10” (25cm) walls roof and floor slabs to create useable spaces, the concrete building elements of an am-cor ferrocement structure of similar size are from 0.5” (1cm) to 2” (5cm) thick. The savings in material and in CO2 emissions average around 70%-80%, not to mention the lower carbon footprint because of time, labor, and transportation savings due to factory prefabrication.
This is a huge savings, and most importantly, Ferrocement structures are actually rated to be stronger and safer than reinforced concrete buildings (especially during earthquakes)!
Ferrocement, the long-forgotten sister method to reinforced concrete, can be a civilization-saver by greatly lowering the volume of anthropogenic CO2 released in construction, and so mitigating climate change.
Let me know what you think!