As part of a new national research program called the Asphalt Research Consortium (ARC), Bahia is now using $5 million in funding to study ways of making asphalt more environmentally sustainable. UW-Madison is one of only five institutions nationwide to participate in ARC, the Federal Highway Administration's first major consortium to improve asphalt technology since the Superpave effort of the early 1990s.
More than 90 percent of U.S. roadways are paved with asphalt, which means any modifications that boost its recycled content, lengthen its life, or cut the energy needed to manufacture it could have a big impact on the environment and our pocketbooks, says Bahia. One of his first goals is to develop so-called "cold mix" asphalts for widespread introduction into the United States. Places like Africa and India have used them for decades, and research shows they can save up to seven times the energy of their hot mix counterparts.
"This is a no-brainer," says Bahia, who has studied asphalt for more than 20 years. "If any person involved in managing our infrastructure looks at the data, why would you spend more energy and money on something else? But the challenge will be to show through advanced design of these materials that the performance is equal."
Asphalt is a byproduct of oil refining; essentially, it's the black, sticky stuff that remains after fuel and lubricating oil are extracted from crude petroleum. It's too thick, however, to be laid on roads as is. That's why in places like the United States and Europe, it's first heated to temperatures as high as 300 degrees Fahrenheit, making it easy to pump and apply.
Other parts of the world have taken a very different approach. In South Africa, for example, asphalt is made workable by shearing it into fine particles, and then mixing it with water and soap-like chemicals called surfactants. The surfactants keep the asphalt in solution until it's laid, after which it hardens to form the road surface.
Studies by Canada's Office of Energy Efficiency and others have found that paving with these cold mixes (also called emulsions) saves significant amounts of energy, especially when combined with recycling efforts. These asphalts also cut emissions of carbon dioxide and other gases. But a number of issues remain, and this is where Bahia hopes his research will make a difference.
"At U.S. refineries today, there are very mature, established specifications for hot binders - our paving grade asphalts," he says. "But for emulsions, there is no clear agreement on how to define the quality. So, we have emulsions already, but we don't produce them as much because the specifications aren't as clear."
Realizing that his own knowledge was incomplete, Bahia traveled during his sabbatical last year to South Africa - a hot bed for cold mix research - and returned brimming with ideas for advancing the technology even further. Eventually he'd like to experiment with adding materials to cold mixes, such as polymers or plastics, which can make pavements quieter, safer and more durable. In fact, these "modified" asphalts are the major thrust of a new campus center he's establishing called the Modified Asphalt Research Center (MARC).
But before embarking on those studies, Bahia first wants to develop quality control tests and standards that will encourage U.S. engineers, chemists and road builders to adopt cold mix asphalts, or at least give them a try. This means first defining the critical ways in which these asphalts fail, and designing systems for detecting the failures.
"We can then determine the chemistry or physics that will give us a larger margin of safety from these failures," says Bahia. The final step will involve simulating various climate conditions in the laboratory to see how failure limits change with freezing cold or blazing heat.
But if green asphalts hold such promise, why haven't these standards been worked out here before? In short, we haven't had to, Bahia says. Until now, we've gotten away with using more expensive and energy consuming hot mixes because of our wealth of resources. Meanwhile, countries such as South Africa and India haven't had the same resources at their disposal.
"In South Africa, they initially decided to go with the low-energy approach because it can save a lot of money," says Bahia. "Then as their economy grew, they had to build high-performance roads. But instead of switching to hot mixes, they improved their knowledge to build better cold mixes."
Now, as concerns about energy and climate change continue to mount, these asphalts are starting to spread beyond the developing world. Paris, France, recently mandated that all new roads be built with lower temperature mixes for environmental reasons. And in North America, there have been many trials with warm mixes that are a step between hot and cold. It gives Bahia hope that the United States will eventually adopt the technology, too.
"Why are we spending so much money on something else? I think there's a very good reason: lack of sufficient knowledge," he says. "And our job as a university is to provide the knowledge that will hopefully one day get us there."
For more on the MARC program, visit http://uwmarc.org/
Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel
Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
23.04.2018 | Physics and Astronomy
23.04.2018 | Physics and Astronomy
23.04.2018 | Trade Fair News