Cold In-Place Recycling

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Mix Design

A mix design is recommended for all CIR applications. Adjustments may be required in the field to the recycling agent design content to obtain optimum performance. If materials vary along the project, more than one mix design may be required. See ARRA publications CR201 and CR202 for emulsified asphalt and foamed asphalt CIR mix design and preconstruction sampling and testing procedures, respectively. AASHTO has developed a provisional mix design procedure for CIR and CCPR using emulsified asphalt and foamed asphalt based on CR201 and CR202, respectively. They are AASHTO PP 86-17 and AASHTO MP 31-17 for emulsified asphalt and AASHTO PP 94-18 and AASHTO MP 38-18 for foamed asphalt. Below are the typical steps for a CIR mix design:

  1. Obtain samples from the existing pavement
  2. Determine binder content and gradation of extracted aggregate
  3. Determine aged binder properties, if desired
  4. Crush materials to produce RAP and determine gradation
  5. Select type and grade of bituminous recycling agent (emulsion, foamed asphalt)
  6. Select type and amount of recycling additives if required (corrective aggregate, cement)
  7. Prepare and test specimens
  8. Establish job mix formula
  9. Make adjustments in field as necessary