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Task 4.3: Introduction of RA in the mixing pr

The aims of this task 4.3 are:

  • To study and identify from the existing knowledge the pros and cons of different selected designs of asphalt plant
  • If possible – to estimate the limitations or ranges for utilization of RA in the different selected mixing scenarios.
  • To cooperate with Task 2.2 in providing information about the existing industrial installations and processes so that equivalent laboratory mixing procedures can be determined.
  • If possible - to utilize the "Laboratory mixing procedure" from Task 2.2 in a few demonstration trials with different types of introduction of RA or with asphalt plants run under various conditions producing different mix types. The quality and homogeneity of the produced material can then be assessed through laboratory tests.
  • To promote recycling RA in countries with low level of confidence in the quality of reused asphalt

Many types of asphalt plants can be used for recycling RA, but due to the individual set-up of the plant different limitations can be imposed on the utilization of RA. Cold feed conveyor belts directly into the mixer of a batch plant may be acceptable for low percentage of RA, while heating the RA separately in a parallel drum for the batch plant or in a double barrel drum mixer will let you achieve higher percentage of RA in the asphalt material and higher production capacities as such. Expected results are recommendations on special issues like potential solution to troublesome mixing situations that may occur (like reuse of RA containing PMBs).

The main focus of task 4.3 is hot mix recycling, but in the frame of the tasks also other ways of recycling are discussed.
Selected mix plant designs based on different types:

  1. Cold RA method (cold feed into the batch mixer)
  2. Warm RA method (parallel drum into the batch mixer)
  3. Mixed design of cold and warm RA method
  4. Double barrel drum mixer plant
  5. "In-situ" methods:
  6. Cold in place recycling with foamed bitumen
    b. RESHAPE
    c. REGRIP
    d. REMIX
    e. REMIX+

Picture 1: Stockpile of milled reclaimed asphalt (CMC - Slovenia)
Picture 2: Stockpile of slabs of reclaimed asphalt (CMC - Slovenia)


Picture 3: Cold RA method (cold feed into the batch mixer) (CMC - Slovenia)
Picture 4: Conveyor belt for adding reclaimed asphalt in the back end of the virgin drum dryer in a batch plant (Denmark)


Picture 5: Batch plant with two routes for recycling the reclaimed asphalt: a vertical system for adding RA directly in the mixer, and a horizontal conveyor belt for preheating RA in the virgin drum dryer (Denmark)


Picture 6: The recycling process of "in-situ" method: Cold in place recycling with foamed bitumen


Picture 7: Recycling train for cold in place recycling with foamed bitumen (Primorje – Slovenia)
Picture 8: Pavement after cold in place recycling with foamed bitumen (Primorje – Slovenia)


Participants in Task 4.3
Zavod za gradbeništvo Slovenije (The Slovenian National Building and Civil Engineering Institute, ZAG, SI),
Centre de Recherches Routières (Belgian Road Research Centre, BRRC, BE),
Danish Road Institute (DRI, DK),
Peab Asfalt AB (PEAB, SE),
Transport Research Laboratory (TRL; UK),
The Technische Universität Carolo-Wilhelmina zu Braunsweig, Institut für Strassenwesen (TUBS, DE),
Laboratório Nacional de Engenharia Civil (The Portuguese National Civil Engineering Laboratory, LNEC, PT).