6) Cold RAP (Recycle Asphalt Pavement) Mix Design

SUPERPAVE Digest 195

Topics covered in this issue include:

6) Cold RAP (Recycle Asphalt Pavement) mix design

by "Murari Pradhan" <>

8) Re: Cold RAP (Recycle Asphalt Pavement) mix design

by "Allan J. McInnis" <>

To: <
Subject: Cold RAP (Recycle Asphalt Pavement) mix design
From: "Murari Pradhan" <
Date: Thu, 17 Jun 1999 16:35:07 -0600

Has any one tried cold RAP mix design using Gyratory compactor? Information on the mix design procedure will be highly appreciated.

Thank you.

Murari

To:
Subject: Re: Cold RAP (Recycle Asphalt Pavement) mix design
From: "Allan J. McInnis" <
Date: Thu, 17 Jun 1999 18:38:04 -0600

The City of Orem is considering using a cold RAP mixture as a treatment on existing, old, cul de sacs. We to are also looking for success / failure stories, so as not to repeat history.

Many of our cul de sacs have sufficient base strength but are lacking AC thickness. Funding cut backs are preventing the proper structural overlay. Cold RAP poses as an economically alternative to those very low volume roads. We are looking for ways to reuse our own tailings from future projects that will be pulverizing existing roads and edge milling. Applying a new cold mix design in small steps, at minimal expense is our goal. We do not anticipate anything more then small batches, 2 to 3 cul de sacs at a time, two to three times (up to 9 total), and then see if success can be documented.

Any thoughts, input and ideas from you would be high regarded. The City does not have a Gyratory compactor but I have been allowed into UDot labs in the past, to do work in and around other work loads. I expect to spend most of the lab time in July.

We are still at the planning stages and have not set any firm dates, late summer and next summer applications seams most likely. I'll get one shot at a series of trials. Not sure who will mix the batches, City crews will transport and lay it. I'll test it. Shadow tests will probably be set up with an independent Lab. Testing budget is +/- $3000

It may be possible to process a few ideas through the lab, and apply a few trials on a road... with risking a highway.

Interested?

Thanks for any response,

Allan McInnis

Pavement Management

SUPERPAVE Digest 196

Topics covered in this issue include:

4) RE: Cold RAP (Recycle Asphalt Pavement) mix design

by "Thomas, Todd" <>

5) Re: Cold RAP (Recycle Asphalt Pavement) mix design

8) Re: Cold RAP (Recycle Asphalt Pavement) mix design

To: "''"<
Subject: RE: Cold RAP (Recycle Asphalt Pavement) mix design
From: "Thomas, Todd" <
Date: Fri, 18 Jun 1999 09:00:49 -0500

You may want to contact the Dr. Wayne Lee or Todd Brayton at the University

of Rhode Island. They are conducting research on cold in place recycling

(CIR); part of the study involves using the Superpave gyratory compactor.

The study has a web site at:

Additionally, a paper was published at CTAA last year by Katherine Lauter

and Michael Corbett of the Regional Municipality of Ottawa-Carleton on

gyratory compaction on CIR. It should provide useful information.

Todd Thomas

Koch Materials Co.

To:
Subject: Re: Cold RAP (Recycle Asphalt Pavement) mix design
From:
Date: Fri, 18 Jun 1999 09:01:19 -0500

We've had both success and failure. We took a design from Koch and used

Coswell-Orth (sp) to process the RAP to uniform size. A rejuvinating agent was

added to the RAP. You can contact Koch, Coswell-Orth or our Research division

for more information. We used it on maintenance projects with low volume roads.

In research contact:

Wilson Brewer

405-521-2671

Kenneth Hobson

Bituminous Branch Manager OKDOT

405-522-4918 405-522-0552 fax

To:
Subject: Re: Cold RAP (Recycle Asphalt Pavement) mix design
From:
Date: Fri, 18 Jun 1999 12:29:49 -0500

Here is a little more information on the cold recycle failure:

4 designs were used on the research project that failed. 2 of the 4 used

anionic emulsions with polymer and a rejuvinating agent. The other two were

cationic emulsions with polymers and no rejuvinating agent. The cationic mixes

failed with raveling and pot holes.

With certain aggregate and RAP sources you may find a success using cationic and

failure with anionic.

The success I told you about used an anionic emulsion with rejuvinating agent.

I am not sure if it had a polymer or not. It was done on a low volume road in

our division 5 near Clinton, Oklahoma. It was near a grain elevator if I recall

correctly so it had some heavy farm equipment on it occasionally. It has been

down for about 2 years.

I don't know what roadway densities we got but they were lower than typical

HMA's. Maybe more research is needed to accomplish better density thereby

increasing performance. Maybe a modified laydown process could help? One

trade-off for more compaction is breakage of aggregates.

We have a project underway now that will use cold RAP on a low volume roadway on

the shoulders only. It will use an anionic emulsion with polymer and a

rejuvinating agent.

Hope that helps.