September 4, 2009

This spring, UW-Madison formally approved the establishment of the Modified Asphalt Research Center. Among MARC's next steps will be to hold discussion forums with faculty members and representatives of the modified asphalt community (including several WHRP members) to define and prioritize the most critical research needs for the center. As MARC researchers move forward with these plans, they will address two driving forces in the development and deployment of modified asphalts: environment and sustainability. As a follow-up to its white paper on the topic, MARC is focusing on these key points:

• Bring attention to green construction. While the climatic and environmental impact of the transportation system as a whole has become a top-of-mind issue, discussions of climate change and energy consumption seldom focus on pavement construction methods and techniques. Sustainable pavements need to be part of the solution to minimize transportation's energy consumption, emissions and environmental impact.
• Define the metrics of sustainability. Rapid deployment of sustainable paving methods and technologies depends on understanding where the industry currently stands on key sustainability indicators. Identifying information shortages will help bring researchers, material manufacturers, contractors and road authorities to a consensus on metrics used to evaluate pavement sustainability.
• Innovate through collaboration. Existing methods to quantify pavement sustainability can be supported by data derived from a variety of sources and techniques. The scientific community should foster research, innovation and entrepreneurship in difficult economic times through international collaboration.

In support of these and related issues, MARC research is focused on identifying, testing and validating alternative pavement technologies that show promise in reducing energy consumption. Initial efforts have modeled energy consumption in manufacturing processes and investigated quantitative life-cycle analysis tools for assessing pavement sustainability. Upcoming research efforts will investigate performance characteristics and behaviors of low-energy asphalt mixes.

May 26, 2009

The MARC research team released a white paper addressing the potential for asphalt pavements to become a sustainable transportation infrastructure solution. Authored by Timothy Miller and professor Hussain Bahia, the paper “Sustainable Asphalt Pavements: Technologies, Knowledge Gaps and Opportunities (PDF, 901 kB)” addresses challenges in defining and measuring asphalt pavement sustainability; highlights available tools and models; and discusses next steps to further develop knowledge for the asphalt paving industry in the areas of energy consumption, emissions and environmental impacts.

One of the tools that MARC is using is BASF's eco-efficiency model. In this approach, a spider graph (shown at right) is used to compare different technologies in six different aspects of sustainability. MARC projects address several of these areas:

• Energy consumption. MARC is conducting research on reduced-energy asphalt mixtures, such as warm-mix asphalt and asphalt emulsion technologies
• Resource consumption. MARC research is helping define the contribution of recycled asphalt pavement to pavement performance; the goal is optimizing RAP use and minimizing consumption of virgin resources.
• Risk potential. Increased pavement life helps lower investment risk. By characterizing asphalt material properties, MARC research seeks to improve pavement performance and extend service life.
• Emissions. To fully determine the benefits of using reduced-temperature asphalts, MARC is studying the emissions that result from heating asphalt materials.

MARC is currently seeking input and feedback on this white paper from the asphalt community.

February 6, 2009

Investigators at UW-Madison's Modified Asphalt Research Center made significant progress over the last several months on research related to skid resistance, pavement friction and noise. Advances in this area will help make asphalt pavements safer and quieter, a shared concern of the WHRP Flex TOC.

• Texture Evaluation and Prediction. MARC researchers worked on laboratory procedures and prediction models for the evaluation of macro- and microtextures of asphalt pavements. Results will help form a mixture design methodology that will address not only pavement strength and durability but also traffic safety, motorist comfort and reduced pavement-tire noise.
• Measuring Sound Dissipation. The team at UW-Madison has been developing a sound absorption device to measure a pavement's ability to dissipate sound energy, similar to other devices employed at the National Center for Asphalt Technology. Open graded friction courses and stone matrix asphalt have the ability to absorb the sound resulting from pavement-tire interaction, and MARC's waveguide device will be an important tool in measuring the energy absorbed or reflected by these pavements.
• Field Testing Devices in the Lab. MARC researchers are evaluating the potential for field testing devices in obtaining information about the textural and frictional characteristics of mix designs before they reach the field. As part of an FHWA equipment loan program, UW-Madison is evaluating both a Circular Texture Meter and a Dynamic Friction Tester.

October 29, 2008

Researchers at UW-Madison's Modified Asphalt Research Center continue to address critical needs related to modified asphalts. These advances have generated significant interest in recent months:

• Recycled Asphalt Pavements. Asphalt pavements must be recycled with care because the properties of the asphalt binder change with age. MARC researchers have developed a protocol to estimate the low-temperature rheological properties of binders in the RAP without the damaging effects of solvent extractions. The results so far are encouraging: The new procedure captures the effect of aged properties of asphalt binder in the RAP and can also estimate the low temperature PG grade of the blended binder.
• Foamed Asphalt. Foamed asphalt is a relatively new process in the United States by which moisture is injected into hot paving-grade asphalt binder, giving the asphalt a low-viscosity, foam-like consistency suitable for coating aggregates at lower temperatures. Foamed asphalt has several potential benefits, including reduced energy requirements due to lower production temperatures and as a method to mix asphalt with cold and damp aggregates for applications in partial and full depth recycling projects.

MARC researchers recently acquired a specialized device for foaming asphalt in the lab, the Wirtgen WLB10. Professor Kim Jenkins and student Andre Greyling, both from the University of Stellenbosch, South Africa, recently visited UW-Madison to shared their experience with this equipment. They will collaborate with UW-Madison on an ongoing basis on cold mix asphalt emulsion applications.