Last July I wrote a blog entitled The Future of Building Materials. In that post, I discussed new building materials that draw from nature, are made from waste material, or have the capability of helping make the planet a cleaner place to live. There are three good reasons that the search for new building materials continues apace. First, the latest predictions have the global population continuing to grow through the end of the century. [“U.N. Forecasts 10.1 Billion People by Century’s End,” by Justin Gillis and Cecelia W. Dugger, The New York Times, 3 May 2011] All of those future residents of earth are going to need to be sheltered. Second, in order to keep the global economy growing, trillions of dollars in new infrastructure needs to be built or replaced. [“Chart of the day: Buddy, got $40T to spare?” Thomas P.M. Barnett, Globlogization, 2 July 2010] Finally, new materials are needed as substitutes for construction in areas where some materials (like lumber) might be scarce or unaffordable. Since writing the post mentioned above, I have continued to collect articles on building materials as I’ve run across them. Most of the articles have been written by the good folks at Gizmag. Like the materials discussed in the previous post, those mentioned below serve a number of purposes. Some of them involve using modern nanotechnology and others use material commonly found in nature. Let’s begin by looking at building materials aimed at helping keep the environment clean and healthy.
Materials that Help the Environment
Ben Coxworth helps start this discussion by introducing us to metal-organic frameworks [“New materials could soak up carbon emissions,” Gizmag, 1 June 2010]. Coxworth writes:
“Imagine a material that appears to be the size of a sugar cube, but when you unfold it, you discover it has the surface area of a football field. Besides its unbelievable surface area, this substance can also be tweaked to absorb specific molecules. Such materials are called metal-organic frameworks, and could be ideal candidates for filtering the carbon out of smoke stack emissions. With that end in mind, a team of California chemists are now racing to create a metal-organic framework that can be used in an industrial carbon sponge.”
The nuclear disaster in Japan has caused a lot of people to reconsider the future of nuclear power. That means that coal is likely to remain the fuel of choice as new powerplants are built to fill the future electrical power generation gap predicted by most analysts. If highly effective metal-organic framework filters can be developed, these new coal-fired facilities will have less environmental impact than currently feared.
As the global middle class emerges, those in its ranks are discovering the joys of having discretionary income. In some countries, like China and India, the new middle class has fallen in love with the automobile. As developed countries learned the hard way, lots of automobiles mean lots of pollution. To help mitigate this problem Dutch researchers are developing air-purifying concrete [“On the road to cleaner air with air-purifying concrete,” by Darren Quick, Gizmag, 7 July 2010]. Quick reports:
“Although much of the focus of pollution from automobiles centers on carbon emissions, there are other airborne nasties spewing from the tailpipes of fossil fuel-powered vehicles. These include nitrogen oxides (NOx). In the form of nitrogen dioxide it reacts with chemicals produced by sunlight to form nitric acid – a major constituent of acid rain – and also reacts with sunlight, leading to the formation of ozone and smog. … Testing has shown that surfacing roads with air purifying concrete could make a big contribution to local air purity by reducing the concentration of nitrogen oxides by 25 to 45 percent. Last fall in the municipality of Hengelo, the Netherlands, researchers at the Eindhoven University of Technology (TU/e) resurfaced around 1,000 square meters of the busy Castorweg Road with air-purifying concrete paving stones, while another area of 1,000 square meters was surfaced with normal paving stones. The air-purifying concrete contains titanium dioxide, a photocatalytic material that removes the nitrogen oxides from the air and converts them into harmless nitrate with the aid of sunlight. The nitrate is then rinsed away by rain. The researchers carried out three air-purity measurements on the Castorweg last spring, at heights of between a half and one-and-a-half meters. Over the area paved with air-purifying concrete the NOx content was found to 25 to 45 per cent lower than that over the area paved with normal concrete.”
Ben Coxworth reports that air-purifying paving slabs are also being tested in Germany [“Air-cleaning paving slabs assessed in Germany,” Gizmag, 18 August 2010].
Wool & Seaweed Bricks
As I mentioned earlier, building homes for people who are expected to swell the global population through the rest of the century is going to be a big challenge. Finding materials that can be used to build those homes and that also have minimal impact on the environment is, therefore, critical. Ben Coxworth claims that wool and seaweed bricks may be part of the solution [“Wool and seaweed makes bricks stronger,” Gizmag, 5 October 2010]. Coxworth reports:
“In a collaborative study on sustainable building materials, researchers from Spain’s University of Seville and Glasgow’s University of Strathclyde have created bricks that contain sheep’s wool and a polymer derived from seaweed. Clay-based soils were provided by Scottish brick manufacturers, while the wool came from Scotland’s textile industry, which produces more of the stuff than it can use. The polymer was an alginate, which occurs naturally in the cell walls of seaweed. Mixed together, the three substances resulted in bricks that were reportedly 37 percent stronger than regular unfired bricks. … The bricks are environmentally-friendly in that they are composed of sustainable, non-toxic, locally-available materials, and don’t require the expenditure of energy that goes into the firing of other types of bricks. … The wool-and-seaweed bricks also don’t create the carbon dioxide that is generated by the production of Portland cement, which is an ingredient in most types of concrete.”
Hempcrete is exactly what it sounds like — a building material based on hemp [“The house made of hemp,” by Grant Banks, Gizmag, 30 November 2010]. Banks reports:
“America’s first house made primarily of hemp has been built. Using a product known as Hemcrete – a mix of industrial hemp, lime and water – a team of 40 volunteers, sub-contractors and designers have recently completed construction of a hemp house located in Ashville, North Carolina (NC). Eco-friendly design and construction company Push Design has gained the support of community members and local officials alike and now plans to build more. Using hemp as a building material is not new. Hemcrete is a registered brand of hempcrete, a material has been an alternative building material used in Europe and Australia since the 1960’s. The use of hemp in buildings dates back millennia in Asia and the Middle East where the Cannabis plant originates from. The biggest challenges of using hemp as a building material in the U.S are regulation, supply and cost, all of which are related. … Given the restrictions on hemp production in the U.S, Push Design sourced their industrial hemp from the U.K through the company Tradical via a fellow NC company Hemp Technology. … Hempcrete has some interesting qualities one of which is it’s ability to pull carbon from the atmosphere both while being grown and while in-situ producing a double edged sword for fighting climate change.”
Banks also reports that as the lime in the Hempcrete ages it calcifies, which actually makes the walls stronger over time. For those of you wondering about getting high on hemp, Banks reports that you would have to smoke “2500 lbs of the hemp to get high.” That means you won’t have to worry about local teenagers coming around trying to sample your house like Hansel and Gretel.
Recycled Plastic Panels
One of the challenges that emerged out of the disaster in Japan is emergency and replacement housing. Similar challenges arose after Hurricane Katrina on U.S. Gulf Coast and following the tidal wave that devastated Banda Aceh in Indonesia. One proposed solution is to erect houses built from panels made of recycled plastic [“Recycled plastic housing resists earthquakes, hurricanes, rot, insects and mould, ” by Karen Sprey, Gizmag, 10 January 2011]. Sprey reports:
“The ECO:Shield system from Innovative Composites International Inc. (ICI) may present a welcome solution [to providing housing in the aftermath of a natural disaster]. The earthquake and hurricane resistant houses use recyclable materials and according to ICI, are cheaper than both conventional and other modular constructions. They are energy efficient and durable – resisting moisture, insects, rot and mold. And they can be constructed quickly using unskilled labor: an 8′ x 16′ (2.4 x 4.9 meters) ECO:Shield house can be assembled in less than 45 minutes with standard tools. … The housing is based on composite panels. A rubber seal is used to attach the plastic structure to the concrete slab used as the foundation (other foundations can also be used), enabling the house to ‘float’ above the foundation and provide flexibility in high winds or earthquakes. The panels provide seamless construction, minimizing the risk of air leaks, and provide an insulation level of R7.6-R17. An open interior floor plan negates the need for load-bearing walls, and any interior walls that are used can be easily moved to customize the floor plan. The ability to use unskilled labor allows local populations to take ownership of building their own homes and other facilities such as schools, offices and hospitals.”
Some critics wonder how well the plastic will hold up under withering sunlight. I see that as just another challenge for scientists to overcome. Time will tell.
Greenhouse Gas Bricks?
Students studying at Michigan Technological University claim to have designed and constructed a mini-smokestack that scrubs carbon dioxide from emissions while at the same time creating a solid material that could be used for construction [“CO2 scrubber turns carbon emissions into building materials,” by Steven Hondrogiannis, Gizmag, 6 April 2011]. Hondrogiannis reports that “the students are being discreet with some of the detail due to patents pending,” but here is what he can tell us:
“The smokestack is packed with glass beads, where a proprietary liquid drips down from the top as carbon dioxide bubbles up from the bottom. As the gas floats to the top, the CO2 is soaked up by the liquid, halving the emissions. The captured carbon reformed into a solid may then be sold and used as a construction material – the exact nature of which hasn’t been revealed – with the remaining liquid recycled into the process once more.”
A company called Calera is already marketing a technique for turning carbon dioxide into a building material. Its website reports:
“The heart of the Calera process is the technology associated with carbon capture and conversion to stable solid minerals. We refer to this new process as Mineralization via Aqueous Precipitation, or MAP for short. In its simplest form MAP involves contacting gas from the power plant with water. The water chemistry is controlled such that the carbon dioxide in the power plant gas is absorbed into the water and reacts with the water hardness to form solid mineral carbonates and bicarbonates, which are very similar to finely disseminated ‘whitings’ seen in tropical oceans at mid-day. These solid mineral carbonates and bicarbonates now contain carbon dioxide that would have been emitted into the air. After removal from the water and with further processing, the solids have value in a number of construction applications.”
I’ll conclude this discussion with three more exotic materials, liquid glass, metallic glass, and self-healing polymers.
What good is liquid glass? According to Ben Coxworth, “The possible uses are endless.” [“Nanopool says the case is clear for spray-on glass,” Gizmag, 10 February 2010]. He writes:
“Spray-on glass … could revolutionize the fields of agriculture, medicine, fashion, transportation – really, it would be easier to list where it might not be applicable. The remarkable product, called Liquid Glass, was developed by the German nano-tech firm Nanopool GmbH. Their patented process, known as ‘SiO2 ultra thin layering’ involves extracting silica molecules from quartz sand, adding them to water or ethanol, and then … well, they won’t tell us what they do next, but the end result is a 100 nanometer-thick, clear, flexible, breathable coating that can be applied to almost any surface. We’re told that there are no added nano-particles, resins or additives – the coating is formed using quantum forces. … Liquid Glass can sprayed on within seconds, creating an anti-microbial, easy-to-clean barrier that will last from one to several years, depending on the surface. It has already been used at Ataturk’s Mausoleum in Turkey, in certain UK hospitals, on a train, and on furniture. Liquid Glass has also been used in agricultural trials, where it was applied to the leaves and seeds of vines. The leaves were successfully protected from mildew, while the seeds didn’t require anti-fungal chemicals. It could also be used on clothing such as gowns or tuxedos, on kitchen surfaces (it’s food-safe and environmentally-friendly), on car interiors – really, on anything that people want to keep clean. Because you would essentially just be cleaning glass, objects treated with it would supposedly clean up easily with plain water, as opposed to harsh cleansers.”
One can imagination how this product might help everyone from archaeologists trying to protect priceless finds to messy eaters trying to protect their clothing.
Metallic glass sounds like an oxymoron (like a lead balloon or jumbo shrimp). But Jude Garvey reports that researchers have developed a glass that is stronger than steel [“Superstrong metallic glass developed,” Gizmag, 11 January 2011]. Garvery writes:
“It seems hard to believe that glass could be stronger than steel, but a team of researchers has developed a super-strong metallic glass that has incredible plasticity when placed under stress, making it as strong and tough as metal. Typically, the structure of glass is strong but brittle which can cause cracks to develop and spread. The new metallic glass features palladium which has a high ‘bulk-to-shear’ stiffness ratio. This allows the metallic glass to bend rather than crack – giving it a fracture toughness that goes beyond the limits of some of the strongest and toughest materials known. The team from the Berkeley Lab and the California Institute of Technology (Caltech) created a pure glass material with a unique chemical composition that when placed under pressure, makes the glass form multiple shear bands rather than developing a crack. This property makes it much more damage-tolerant than other metallic glass.”
Obviously, people living in areas prone to hurricanes, tornadoes or living in vulnerable spots on golf courses could use a product like this. The anticipated cost of the materials was not given.
Self-healing Biorenewable Polymers
In the post mentioned at the beginning of this blog, I discussed several self-healing materials. Work on such material continues [“Scientist developing self-healing biorenewable polymers,” by Ben Coxworth, Gizmag, 11 January 2011] Coxworth reports:
“Materials that can repair themselves are generally a good thing, as they increase the lifespan of products created from them, and reduce the need for maintenance. Biorenewable polymers are also pretty likable, as they reduce or even eliminate the need for petroleum products in plastic production, replacing them with plant-derived substances. Michael Kessler, an Iowa State University associate professor of materials science and engineering, and an associate of the U.S. Department of Energy’s Ames Laboratory, is now attempting to combine the two. Self-healing materials generally incorporate microcapsules containing a liquid healing agent, and catalyst elements, which are embedded within the material’s matrix. As cracks form within the matrix, the microcapsules rupture, releasing the healing agent. As soon as that agent encounters the catalyst, it hardens into three-dimensional polymer chains, thus filling and securing the cracks. … Since 2005, Kessler has been working with Iowa State‘s Prof. Richard Larock on the development of biorenewable polymers made from vegetable oils. Larock is the inventor of a process wherein bioplastics can be created that consist of 40 to 80 percent inexpensive natural oils – these plastics reportedly have very good thermal and mechanical properties, are good at dampening noises and vibrations, and are also very good at returning to their original shape when heated. Kessler is now trying to create self-healing versions of these same plastics.”
All of these materials are interesting and are likely to help us move more prudently into the future. I’ll keep my eye out for other stories about innovative building materials in the months to come.