Green Options

Concrete that maintains itself by healing cracks improves the sustainability of infrastructure through its longer service life and lower maintenance inputs. Now researchers have developed flexible, self healing cement that won’t suffer catastrophic failure when strained in an earthquake.

British engineers have developed a new environmentally friendly cement that is carbon-negative.

Cement, a vast source of planet-warming carbon dioxide, could be transformed into a means of stripping the greenhouse gas from the atmosphere, thanks to an innovation from British engineers.

The new environmentally friendly formulation means the cement industry could change from being a “significant emitter to a significant absorber of CO2,” says Nikolaos Vlasopoulos, chief scientist at London-based Novacem, whose invention has garnered support and funding from industry and environmentalists.

The new cement, which uses a different raw material, certainly has a vast potential market. Making the 2bn tonnes of cement used globally every year pumps out 5% of the world’s CO2 emissions - more than the entire aviation industry. And the long-term trends are upwards: a recent report by the French bank Credit Agricole estimated that, by 2020, demand for cement will increase by 50% compared to today.

[Image Credit: Mikko Itälahti on Flickr under a Creative Commons license]

Fly ash and bottom ash are byproducts from coal-fired power plants. Both are environmental hazards, and their disposal is toxic and costly. Small amounts of these materials can be reused in concrete production, but the rest ends up in landfills or storage lagoons. Georgia Tech assistant professor Mulalo Doyoyo is looking to solve that problem and create a greener, cement-free concrete alternative to boot!

New ideas for reducing CO2 seem to be popping up all the time. The latest scheme for getting rid of the greenhouse gas comes from Stanford Professor Brent Constanz. The Geological and Environmental Sciences Professor has invented a new type of cement that is carbon neutral—a huge innovation for a material whose production process normally spews vast amounts of CO2 into the atmosphere.

Not only is Constanz’s cement carbon neutral, but it also sequesters CO2 emitted from power plants.

A South African company called Moladi is promoting their system for quickly building homes. Using their system, the exterior walls for a single-family dwelling can be built in a matter of just a day or two, and it can be done using unskilled labor. But, while their goals are admirable, it’s a question whether or not this is a really green method of building.

The system uses lightweight formwork panels, much like those used for poured concrete walls. Once erected, the forms are filled with mortar (concrete without stone) which can be hand-mixed and hand-placed, or which can be mechanically mixed and pumped into place. Typically, the formwork can be removed the day after the mortar is poured. The result is a smooth finish material, little more than a roof is needed to complete the building.

On the downside, this material uses 250 kilograms of portland cement per cubic meter (about 420 pounds per cubic yard), making it fundamentally the same as a concrete building with an enormous carbon footprint stemming from the extensive use of cement in these buildings.