DRUM-DRYER MIXING IN NORTH DAKOTA

A project is described which covered a 28 mile area, and in which the plant provided for a 2-in overlay over an existing asphaltic concrete pavement using 200-300 penetration grade asphalt cement. For observation purposes, small test sections were included using 120-150 and 85-100 asphalt cement. The plant consisted of a 3-bin cold feed unit, a drum (with burner and aggregate feed on the same end) a hot storage bin and control house. As the temperature was raised, the moisture content dropped and the mix became a brownish color. Moisture contents dropped as the aggregates moved from the stockpile through the drum dryer and laydown machine. The compactive effort required to obtain specified density was less at the lower temperatures. An extensive program was conducted which covered aggregate gradations, asphalt content, moisture content, penetration of the recovered asphalt, and the reduction of penetration in the original asphalt content by the Thin Oven Test. Mix designs were based on the 50-blow Marshall Method and actual samples of the mix were checked against the original design by the Marshall test procedures. It was found that high moisute contents and variation in the amount of moisture in the raw aggregate could be a problem. Handling mix as it leaves the drum dryer could also prove a problem. It is estimated that cost savings of at least 50 cents per ton are being realized. Other benefits besides potential cost savings are discussed, and plant components that need further study are listed.

Media Info

  • Features: Appendices; Photos; Tables;
  • Pagination: p. 417-425
  • Serial:
    • Volume: 43

Subject/Index Terms

Filing Info

  • Accession Number: 00125410
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 18 1975 12:00AM