FLY ASH IN COLD RECYCLED BITUMINOUS PAVEMENTS

Since 1986, the Kansas Department of Transportation has been cold recycling about 80 to 160 km of bituminous pavements per year. All of the projects were completed in place, 100 mm in depth, using mostly an emulsified asphalt as an additive, and incorporated a thin surface overlay. However, the emulsified asphalt cold recycle projects can leave a pavement that is susceptible to moisture damage and rutting. Since 1990, fly ash was added to these mixes with and without an emulsified asphalt. Laboratory tests indicated that fly ash would reduce the potential for moisture damage and wheel path rutting. Four test pavements were built between 1990 and 1992. Two pavements incorporated a non-self-hardening fly ash and a Type C fly ash. Water with set retarder was the other additive used. On the basis of the results of this study, the conclusions are (a) fly ash decreases the permeability of the cold recycle mixes thereby increasing the resistance of the mix to the detrimental effects of moisture damage, (b) fly ash increases the strength of the mix and decreases its potential for wheel path rutting, (c) Jeffery ash (Type C) has lower permeabilities and higher strengths than Sunflower ash, and (d) fly ash-only cold recycle mixes have a tendency to ravel under construction traffic. A protective cover material (prime coat, seal, overlay) is necessary even on low-budget projects.

Language

  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 49-56
  • Monograph Title: Environmental testing and evaluation of stabilized wastes, performance of stabilized materials, and new aggregate tests
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00713587
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Nov 22 1995 12:00AM