Phase two of asphalt test track set to begin

The National Center for Asphalt Technology, Auburn, Ala., is getting set for Phase Two of its pavement testing.

Phase 1, which concluded in late 2002, showed little distress to the 46 pavement sections after 10 million ESALs were applied in two years.

Beginning May 1, workers will start removing eight full-depth sections and reconstructing them at varying thickness using modified and non-modified asphalt cements. The new sections will be used to partially validate the new American Association of State Highway & Transportation Officials design procedures and will generate data to help verify perpetual pavement concepts.

About half of the original sections will stay in place; the rest will have the top 4 in. of pavement removed and replaced with a different mix type. Whether to keep the original surface or replace it with a new mix was the option of the sponsoring state. Since results were successful in the first round several states said they wanted to see what would happen to their existing sections with another cycle of testing.

The new sections in Phase Two will require extra instrumentation that was not needed in the first phase. In the 2000-2002 testing period, all the pavement sections were the same thickness and the studies were primarily on the performance of various surface mix types. With different pavement thickness for 2003-2005, researchers will be looking at the stresses and strains in the pavement.