CIPR of Asphalt Pavement (Fly Ash Modified) 3

[MAS2004]

I know Cold In-Place Recycling using Emulsion additive is a popular method. But did anyone here used CIPR method using Fly Ash? We are considering it for a low-volume county road. The horizontal and vertical alignments will remain same. The way I understood the process works is to use a Reclaimer to mill the existing pavement full depth and possibly about an inch into the soil below. Then spread fly ash over it (12-15%), mix all in and compact it. Then put an overlay or chip seal on top of it. Anyone with good or bad experience with this method? I was told that it is cheaper than the emulsion method? Any specifications available? How to make sure the water content and density requirements are met in the field? Thanks for your input.

 

[BigH]

I've not done what you propose to do, but I have done CIPR. I wouldn't use fly ash in place of emulsion but might consider it in place of the normal cement that is used in the mix. Normally, you use an emulsion binder with portland cement filler (aboug 2%) which is placed on the surface being recycled. Fly ash will not provide sufficient "binder" in my opinion. It does have cemetitious properties but they are usually a delayed property. In fact, although I am not fully sure, you might have to add a bit of portland cement with fly ash as a replacement percentage. Hope some others will be able to offer more experience to your query.

 

[BigH]

Just did a search of "CIPR with fly ash" and got the hit below. Apparently 100% fly ash has been used. Info is sketchy so you may need to contact them.

http://www.currancontracting.com/html/cipr_faqs.html

 

[jerrylo]

We used to do a lot of CIPR w/ flyash as a binder. We added around 10% ash to the roadway directly ahead of a milling machine, mill 4" of existing pavement & ash, pugmill the material and place it with a laydown machine. It performs well with an overlay after the CIPR. The pugmill monitors the water,etc electronically and density is done with the old rolling procedure. As far as the properties of the ash, contact your supplier and ask them for the compressive strenght. While not on par with cement, the material is cheap and will provide adequate binder. Although it works well if you have the pavement structure to begin with, I would not recommend it for a full depth recycle. I would look into a lime-slurry/emulsion CIPR that performs much better than the ash or look at milling the material all up, pugmilling it with a suitable oil and lay it back down and applying a seal to finish it off.