Asphalt research paves way to better roads Recent advances in understanding asphalt chemistry could make it much easier to build longer lasting pavements, according to an announcement last week by the National Research Council's Strategic Highway Research Program (SHRP). "We now have an entirely new understanding of asphalt chemistry that has tremendous implications," says SHRP executive director Damian J. Kulash. "This will enable highway engineers to design pavement structures that take full advantage of asphalt's chemical and physical properties. It also will enable refiners and manufacturers to modify asHealy: refused to kowtow phalt materials so they will perform Healy convened a second internal better." Much of this new understanding panel that "expressed concern that misconduct in scientific reporting has resulted from funding from may have occurred." A subsequent SHRP—a five-year, $150 million rehigher level clinic investigation, at search program supported by the which Healy testified that the ac- federal government since 1988. Until about one or two years ago, cused scientist hadn't meant to mislead, concluded there was no mis- most researchers in the field accepted the decades-old notion that peconduct. OSI began its own investigation troleum asphalt has a colloidal or in December. "It seemed to us, to micellar microstructure. According the entire investigative team," Had- to this model, highly polar moleley said at the hearing, "that the cules such as carboxylic acids, keCleveland Clinic Foundation in the tones, and sulfoxides are segregated final analysis didn't want to call into discrete particles that are dissomething misconduct that seemed persed in a high molecular weight, to be manifestly misconduct as we neutral hydrocarbon phase. know it." Recently, researchers in Wyoming At the hearing, Healy repeatedly and Pennsylvania, under contract to bristled at subcommittee members' SHRP and led by J. Claine Petersen attempts to question her behavior, of Western Research Institute (WRI) asking why they did not focus on in Laramie, Wyo., developed a new the second inquiry. "I make mis- structural model that is more fully takes," she said. "I didn't do the first consistent with the chemical and inquiry right, and that's why I physical properties of asphalt. The new model proposes a more unimoved to the second." After learning July 19 about the form distribution of different hydrosubcommittee's concerns, Healy re- carbon molecules having a wide cused herself from all matters relat- range of molecular weights and ed to OSI. However, said Dingell, functionalities, according to engi"The damage had already been neers David A. Anderson and Dondone. These are distressing events ald W. Christensen of the Pennsylthat . . . raise again the question of vania Transportation Institute at whether NIH has the institutional Pennsylvania State University, Uniwill to investigate its grantees, its in- versity Park. Their WRI colleagues, tramural scientists when issues of chemists Raymond E. Robertson and misconduct arise. If not, perhaps it Jan F. Branthaver, describe the promay be necessary to remove OSI posed microstructure as a closely packed, three-dimensional network from NIH." of polar molecules that extends Pamela Zurer
throughout a neutral hydrocarbon medium. The polar functional groups control performance because, in simple terms, they determine how the molecules associate and form networks to give the asphalt strength, but they also allow it to flow like a viscous liquid. If the network is not stiff enough, the asphalt will be prone to rutting. If the network is too stiff, the pavement will tend to crack from fatigue. The network also influences the material's sensitivity to moisture, which can cause the asphalt component of asphalt concrete to separate from aggregate, leading to cracks, potholes, and other damage. This new fundamental understanding of asphalt and asphalt concrete is now being translated by SHRP and major asphalt contractors into a new set of specifications relating much more closely to performance characteristics than previous specifications, Robertson tells C&EN. This is leading to new criteria for selecting the most appropriate asphalt for a particular construction job. In addition, SHRP is developing new tests that manufacturers can use to determine the chemical and physical properties of asphalt cement, and to modify it for better performance. Ron Dagani
U.S. chemical industry to stay competitive A report issued last week by the Council on Competitiveness projects contrasting outlooks for the next 10 years for two major U.S. industrial sectors now enjoying great success in the international marketplace— chemicals and pharmaceuticals. That superiority should continue for the U.S. chemical industry, as it continues to streamline management, upgrade R&D, and adapt to changes in global markets. But the U.S.'s lead in pharmaceuticals— already thin—seems to be eroding. These conclusions emerge from profiles of the strengths and weaknesses of those industries prepared by the council, a Washington-based organization of technological chieftains in industry, academia, and labor. The assessments served as backAugust 12, 1991 C&EN 5
