The Oregon Department of Transportation (ODOT) continues to investigate alternatives for rehabilitating the rutting in concrete pavement sections. The millabrading system was proposed as an option to reduce the middle lane rut depths in a continuously reinforced portland cement concrete pavement to improve driving conditions. Rut depths of 19 to 32 mm were measured prior to construction. The system includes a high speed rotomill with a modified drum used to level out the ruts, followed by a shotblaster with steel shot to provide a uniform, skid resistant wearing surface. The following conclusions were reached following an eight-month investigation: Construction noise levels should be considered if the grinding is to take place near a residential area. Air quality, particularly coarse particulate fallout, may be a problem if the rotomilling is done for an extended period in one area. A post construction inspection measured random rut depths of 10 to 16 mm in the middle lane. Some rutting was expected, however, not to the degree measured. Insufficient survey data may have impacted the design and subsequent outcome. Full-width treatment may have eliminated the ruts. In addition, the longitudinal joints appeared spalled. A petrographic analysis indicated that there is no microcracking that may be detrimental to the durability of the section. Accident data for comparison between the before and after conditions is not currently available. District Maintenance staff report no problems with the section. Field test results indicate that in-vehicle noise levels are noticeably lower after construction. Because some of the pavement ruts still remain, the reduction in noise is dependent on where the tires hit in the lane. Pavement friction values increased following the grinding and additionally after the shot blasting. Friction values, however, have continued to decrease for the last eight months following construction. The pavement ride or roughness appears to be slightly reduced following the millabrading process. Again, since some rutting still remains, the International Roughness Index (IRI) reductions are dependent on where the roughness is measured. Recommendations for future use are included.


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Media Info

  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 38 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00778843
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-OR-RD-00-02,, Construction Report
  • Contract Numbers: FHWA Special Project 205
  • Created Date: Nov 4 1999 12:00AM