Recycled asphalt pavements, sulfur

Table 2. Properties of Recycled Asphalt Pavement Using Sulfur/ Asphalt Emulsion Binder.

Two of the more recent innovations for using sulfur modified binders are in conjunction with recycling old asphalt pavements and the construction of open graded friction courses (OGFC). 

Figure 21. Schematic of a central plant for sulfur recycling of old asphalt pavements.

An additional approach which will result in the conservation of asphalt, which is under investigation by both the Bureau of Mines and Til, involves using sulfur in recycling old bituminous pavements (2,14). Sulfur can reduce the viscosity and hence improve the workability of age-hardened asphalt pavement material and can increase the stiffness of the recycled mix when it cools. 

This chapter discusses current research on the use of sulfur in recycled asphaltic concrete pavements. In addition, it describes the results of laboratory tests and theoretical predictions using the latest linear viscoelastic layered pavement analysis methods (15,16) to compare the performance of various sulfur-asphalt concrete pavements with conventional asphalt concrete pavements in a variety of climates. The relationship between pavement distress and performance used in the computer program was established at the AASHTO road test (17). Finally, the results of domestic field tests of sulfur-asphalt pavements are presented along with a discussion of future trends for the utilization of sulfur in the construction of highway pavement materials. 

Characterization tests reported here were performed on combinations of materials needed to evaluate the predicted performance of typical pavements made from conventional asphaltic concrete with limestone aggregate, sulfur-asphalt concrete with limestone aggregate, sulfur-asphalt concrete with beach sand aggregate, and recycled asphaltic concrete pavement with sulfur added during the recycling process. The data... 

Many existing roads fail because the asphalt becomes stiff and brittle. If the materials are too stiff, additives that lower the viscosity must be used. The feasibihty of usiag sulfur to soften or reduce the viscosity of the oxidized biader ia recycled pavements has been successfully demonstrated by the U.S. Bureau of Mines and others (55—57). 

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