People when they hear green, they dont usually think of Cement and Drywall. They think of renewable energies, natural constructed homes, and recycled materials. Well all that is going to change when a number of new Green Technology companies will start selling their Green materials to the public.
In an article from C&En News dated January 25, 2010, "Seeking to Cement a Green Future," by Melody Voith, I was amazed at how creative people are with the idea of Green Technology, and how they are developing new, more efficient, processes for making materials that we use everyday.
Traditionally speaking, concreate is made by heating limestone in a kiln to about 2500 degrees Fahrenheit. This releases CO2 during the evaporation of water in the limestone. The material leftover is called clinker, which is then ground up. Gypsum, water, sand and other aggregates are added to the Clinker producing concrete mix. When it is rehydrated, an exothermic reaction takes place, hardening the mix.
The Greener way to do this is to reduce the CO2 footprint, or get rid of it entirely. This is what 3 new start-up companies- Calera, Serious, and CalStar- claim to achieved with the making of Cement and Drywall. During Calera's process for cement manufacture, industrial waste CO2 is bubbled into a mineral rich tank of seawater (also referred to as Hard Water). Calcium and magnesium carbonates settle and are removed. These two carbonates are transformed into two concrete ingredients: synthetic limestone aggregate and an amorphous calcium carbonate with "cement-like properties". The process is very similar to what coral reefs do naturally: producing carbonates from seawater in order to build their habitats. Calera estimates this process will not only reduce CO2 production, but in fact absorb up to 1,000 lbs of CO2 (per year). In the article, Calera states that the traditional process generates more than 500 lbs of CO2 (per year).
The company says that they plan to use a low-energy electrochemical process to add alkalinity to the water, in order to create the high pH in the water. The ideal situation calls for a power plant to generate CO2, the concrete mixing facility, and a desalination plant to remove the salts from the water generating raw material for the electrochemical plant.
At Serious Materials, drywall is being re-made with waste materials from metal casting. Gypsum-based drywall for decades has been made my grinding gypsum into powder, heated to 350 degrees Fahrenheit, rehydrated again and spread between layers of paper to create the hardened drywall boards. This process tends to be energy intensive because of the heating stage. The new greener process uses slag, which is a "mixture of nonmetallic components removed from iron ore during steel making". This slag is often composed of calcium and aluminum silicates and mineral oxides. Serious then adds various agents and catalysts to "produce an exothermic reaction which then hardens the material". So the process is very similar to making traditional cement, except that the material used is usually waste material from steel making and is never used. The process also consumed much less energy and CO2 as compared with the traditional process of making drywall. The process for this new drywall, called EcoRock, is estimated to emit 80% less CO2 than the traditional process.
The final company, CalStar, is designing a new process for making greener bricks. Traditionally, bricks are fired for 24-48 hours in an energy guzzling kiln at 2000 degrees Fahrenheit. According to CalStar, the new bricks "require 90% less energy and contain 40% post-industrial recycled materials". The new bricks are made of fly-ash, a waste material from coal-fired power plants, and is mostly composed of lime. The new process takes advantage of the lime composition, so when water and additives are combined with the fly ash, the mix hardens in a chemical reaction, without the need of firing in a kiln.
This material, however, has its downside, which CalStar says is not a problem. The fly-ash, unlike steel slag, contains trace metals, such as mercury, barium, chromium, and selenium, all of which are deadly and toxic, especially when combined together. According to CalStar, "multiple tests have shown that the metals are bound in a crystalline matrix and do not leach in amounts high enough to cause concern for health or the environment". I'm sure this process will have to be looked over and refined several times before it is released to the public. Actually considering a material that contains toxic metals for use in the industrial is a bit unnerving, so I believe the company is going to struggle a bit in the green-building market until they either verify the materials' safety, or find a safer material to use.
So here I talked about 3 companies that are currently researching and developing new processes for creating materials that are used in construction today. One of the three companies, Serious Materials, intends to release their product to the American market sometime this year. I expect that this will be very expensive starting out, and most people will be reluctant to make the switch, but after some good media exposure, people will see that this is a viable product. As for the cement process, that is currently in the works near Monterey, California, but Calera has yet to announce a date when they will release their Green cement to the market.
I hope by summarizing the article, I can inform people of whats new in the Green Markets, and what they can look forward to in the coming year.
Source: Chemical & Engineering News, published by the American Chemical Society. The article is featured in the January 25, 2010 magazine on page 20. The article is called "Seeking to Cement a Green Future", and is written by Melody Voith, from C&N Washington.
