Is glass coming to a concrete near you?

One area that the MacArthur Foundation examined was concrete. Concrete is a common building material, but it has some environmental downsides. Cement – a primary component of concrete – generates a lot of CO2 during its production. Various concrete mixtures can also contain toxic heavy metals like cadmium, arsenic and lead. These toxic inclusions come from fly ash and slag, which are sometimes used in concrete mixtures as a substitute for some of the cement.

Ground glass is being considered as a substitute for fly ash, which is in short supply. Fly ash is a residue generated by coal-fired power plants. No one’s building coal fired power plants today, and as more plants convert to natural gas, the supply of fly ash dwindles further. At the same time, the demand for concrete is rising, so finding an acceptable substitute for fly ash is a priority.

Substituting glass for fly ash could solve a couple of problems. First, it could create a viable market for recycled glass. That’s big because so many cities struggle with glass recycling, and it could remove some of the 8 million tons of container glass from US landfills every year. Second, it could reduce the demand for cement, which could in turn reduce cement-related carbon emissions significantly. Each ton of cement that’s produced releases a ton of carbon into the atmosphere.

Right now, using glass powder (called pozzolan) in place of fly ash would increase the price of concrete slightly – less than 5% – but it would decrease the carbon footprint of concrete to about 10% of its current size by reducing demand for cement. It would also eliminate the need to import fly ash from other places, like China and South America. The Foundation estimates that a pozzolan plant needs about 40,000 tons of container glass each year to keep up with the demand for ground glass, and multiple pozzolan plants would be needed to meet the annual demand for concrete. That’s still significantly less than the amount of glass that gets recycled, but concrete production offers a positive market for recycled glass – something that has so far been hard to come by.

New paint-on coating improves glass efficiency

Researchers at Berkeley National Labs are working to develop a paint-on coating that reflects heat. If successful, the coating could be added to existing windows for about one-tenth the cost of conventional heat-reflective glazes. The researchers even speculate that the coating could be applied by homeowners as a do-it-yourself project.

The coating will be designed to selectively reflect infrared light waves without significantly reducing visible light. Like many energy-efficient coatings, the Berkeley coating will also be designed primarily for use in southern and western climates. These buildings tend to use a significant amount of electricity for air conditioning.

The goal of the development is to create an inexpensive, easy-to-use coating. If they succeed, the coating could reduce energy consumption by as much as 35 billion KWh and 24 billion pounds of CO2 emissions annually. The team’s goal is to create a coating that could be applied for about $1.50 per square foot.

To create the coating, the team will work with a type of polymer known as a “bottlebrush” polymer. The unique shape of the polymer – a rigid spine with bristles that extend from the sides – could help reflect infrared light, while allowing visible light to pass unimpeded.

The work is being funded by the US Department of Energy, and will allow the team to develop, refine and test the coating. Another element of the project is to determine how best to scale production, maximize the coating’s efficiency and distribute the finished product.

Light emitting glass from Down Under

Researchers at the University of Adelaide have developed light-emitting glass. The panes of glass can be used to make highly transparent displays. Because the glass does not lose any of its natural characteristics, it can still be formed into virtually any shape.

To create the glass, the researchers used a technique called direct doping. The technique involves combining both the glass and the previously prepared light-emitting nanoparticles under precise manufacturing conditions and closely controlled temperatures. Managing the temperature allows both materials to retain most of their unique characteristics. The technique is also simpler than other specialized glass fabricating techniques.

Light-emitting glass could be useful in a number of different applications. According to the researchers, the glass could be useful in medical imaging, sensing, and volumetric displays. One potential application (that has yet to be developed), would allow physicians to use light-emitting glass sensors to enter areas of the body that have traditionally been difficult to access, or that are currently only examined with fluorescent dyes.

The scientists created light-emitting glass because they combined glass with photonic particles. The technique could be used to combine glass with other types of particles to make a whole host of glass-hybrid materials. For example, the same technique could be used with electronic, magnetic or other kinds of photonic particles to create conductive or magnetic glass, or glasses with other light-related properties.

The simplicity of the manufacturing technique will allow the researchers (and research teams at other universities) to create and test a range of new materials relatively quickly. Because the specialized nanoparticles are prepared prior to production, the researchers can easily predict the behavior of the resulting hybrid glass.

Glass coated hypodermic needle could ease pain

No one likes getting shots, but a newly developed glass-coated hypodermic needle could reduce the amount of pain associated with getting shots or taking blood samples. Researchers at the National Taiwan University of Science and Technology (NTUST), working with researchers from the University of Tokushima and the University of New Mexico have developed a hypodermic needle coated with metallic glass.

The researchers say that the metallic glass coating reduces pain when the needle is inserted and also improves the performance of the needle. According to researchers, metallic glass has certain properties that reduce the friction associated with the surface of the needle. Friction between the surface of the needle and the skin or other living tissue causes resistance, which in turn causes pain. Longer and larger needles cause more pain because the larger surface generates more friction upon insertion.

Friction doesn’t just cause pain upon when the needle is being inserted. Friction is also generated when the needle is withdrawn because typical metals have a natural surface grain. Movement in any direction causes tissue to “catch” on the surface grain.

Researchers say that applying a metallic glass coating to the needle reduces friction by 2/3rds when the needle is being inserted, and reduces friction by nearly 3/4ths when the needle is being withdrawn. In some experiments, friction was reduced by 80%.

Large-bore needles are typically lubricated because lubrication is known to reduce friction, and insertion pain. Smaller gauge needles are typically not lubricated; these needles are often used in dental procedures, suturing and other medical procedures. Metallic glass coatings could also be used to reduce friction in other non-medical applications, and are of interest to manufacturing and materials sciences engineers.

New film can make any glass “smart”

The Texas researchers collaborated with scientists in France and Spain to create the material. The material, which contains niobium oxide, is about twice as efficient as conventional smart windows. The film is classified as an amorphous structure, which means that its atoms do not ordinarily arrange in a typical crystalline structure.

Conventional materials adopt a uniform, crystalline structure that is replicated throughout the material. Amorphous materials, on the other hand, contain local arrangements of atoms that differ based on the material. Amorphous materials created at high temperatures tend to arrange themselves in dense, three-dimensional bonds. The researchers were able to determine that the new material, which is formed at lower temperatures, does not have the dense 3-D structure, but rather has a linear structure that allows ions to flow more freely through the material. The discovery provided enough information to predict the behavior of the new material and allow the other team members to create it.

The arrangement of atoms in amorphous structures determines what the materials can do. The researchers can use the technique to predict the behavior of other amorphous materials and optimize their performance. The researchers are now focusing on creating a low-temperature flexible material using the new compounds that performs as well as or better than conventional electrochromic materials. Being able to mass-produce the material at low temperatures will simplify the manufacturing process and make it both readily available and affordable.