Beneficial Use of Sulphur in Sulphur-Asphalt Pavements (TTI-1980-1)

The use of sulfur as a means of upgrading poorly graded mineral aggregates for use in asphaltic concrete mixes has been under study by Shell Canada under the trade name of Thermopave for approximately fifteen years. Laboratoryork has been extensive and numerous field trials have been completed in Canada. The Texas Transportation Institute under the co-sponsorship of the Sulfur Institute, and the Bureau of Mines instituted a program to introduce this concept to the United States. Following a 4-year laboratory effort a 3,000 lineal foot (914 m), sand-asphalt-sulfur experimental test section was placed along a portion of U.S. 77 in Kenedy County, Texas. The 3,000-foot section was divided into six subsections of various thicknesses with two sections purposely undersigned to show distress in two to three years. This was the first demonstration of the Shell concept on a Federal Highway in this country. Following this demonstration a 36-month post-construction evaluation program was undertaken involving a series of laboratory tests of cored samples, Dynaflect deflections, Mays ridability and on-site visual inspections. At the end of this 3-year period the sulfur subsections are performing as well as the control sections. In the case of rutting, the sulfur sections are actually performing better than the control. Recommendations have been made to continue this post-construction evaluation for an additional 36 months.