Gerald Huber, Heritage Research Group
As the asphalt industry moves forward, emphasis continues to shift from volumetric properties to performance tests. The quest for suitable performance tests goes back more than 100 years, pre-dating development of Marshall mix design. Marshall stability, developed in the 1930s as an indication of permanent deformation resistance, was used until research in the 1980s indicated a poor correlation between rutting resistance and Marshall stability. In the Strategic Highway Research Program (1987 to 1993) a newly developed mix design method included measurement of engineering properties and prediction of performance. As implemented in the late 1990s, Superpave included only the base level of volumetric design because the engineering property tests were too complex and not ready for implementation. Since SHRP the asphalt industry has grappled with performance-related tests such as wheel track testers and various cracking tests seeking to relate the test results with anticipated performance. Results have been mixed. Engineering properties of asphalt depend on the property of bitumen and aggregates, their proportions in the mixture and their final in-situ compaction. On a separate path, work has occurred in the last 20 years to identify the relationship of engineering properties and volumetric properties. The vision is to measure engineering properties during design and then during construction use the relationship to volumetric properties to estimate engineering properties. These properties can be used to predict performance from fundamental, engineering-based models rather than empirical relationships.
Originally from the Province of Saskatchewan in Canada, Mr. Huber obtained a degree in civil engineering and joined Saskatchewan Highways and Transportation where he worked on highway construction and design.
During his tenure in Saskatchewan, he obtained a Master's degree from the University of Texas that led him to the Asphalt Institute, an industry association in the U.S. At the Asphalt Institute’s research center, he helped develop a new method to design of asphalt pavement called Superpave. Mr. Huber now works as Associate Director of Research for the Heritage Research Group, a private asphalt research office based in Indianapolis. He works with transportation and research agencies at the state, national and international level. He is active in the Transportation Research Board, is Past President of the Association of Asphalt Paving Technologist and is Past Chairman of the International Society of Asphalt Pavements.