Asphalt Millings

[mfio]

An existing parking lot has been milled and the asphalt millings are stockpiled. I was planning to reuse the asphalt milling as a portion of the subbase course materila beneath a new asphalt pavement. The question is: should the millings (max 4" in thickness) should be placed just below the new asphalt (1.5" top; 3" binder), or below the 6" of subbase course (crushed stone). I was reading that conventional granular aggregates do not bond well with RAP or blended granular material containing RAP. Consequently, raveling can occur if thin layers of conventional aggregates are placed over material containing RAP. Also, assuming the millings have a lower permeability of the subbase course (not sure about this), If the millings are placed below the subbase course I may increase a bathtub effect within the subbase course (water trapped within this layer).

Has anyone had experience in reusing asphalt millings as unbound subbase course material benetah asphalt pavement?

 

[Drumchaser]

Sounds like you have a decent budget for materials.....I would not place the RAP under a new pavt. structure.
Have seen problems. Offer the RAP to your asphalt supplier as a cost savings for your new pavement.

In this region it is allowed (10-20%+ or -) to be recycled into new mix at the plant.

 

[Ron]

Unfortunately you have already milled the existing asphalt so Drumchaser's suggestion is appropriate. You could have mixed the existing pavement surface together with its base to create a new base with the injection of asphalt emulsion in the mixing process (a form of cold, in-place recycling)....works well and creates a competent base that is water resistant.