Topics Covered in This Issue Include

SUPERPAVE Digest 215

Topics covered in this issue include:

5) RE: Mixing/Compaction Temperatures by [email protected]

 To: [email protected]

 Subject: RE: Mixing/Compaction Temperatures

 From: [email protected]

 Date: Wed, 21 Jul 1999 08:05:21 -0500 In the design phase we use 163C to mix (minimum 2hours). After 2-4 hours at 149C we mold them. No aging is required for field samples but they should be heated for a minimum of 2 hours at 149C. This ensures that the sample has stabilized at that temperature. There should probably be a maximum on this but we do not have it in our specifications.

As for splitting most use a chute sample splitter though I would not be surprised if some of the older field technicians still use the quartering method. Most times you would have to reheat and split the sample to get your mold specimens, extraction/gradation, rices, etc.

The pam usage on the splitter is not a bad idea. We use an asphalt release agent from our approved asphalt release agents list. This will add moisture to the mix so you have to be sure to adhere to the 2 hour minimum.

The mixing and compaction temperatures on the roadway is another topic. Some say go with what the refinery recommends and others go by the viscosity chart (see mine at http://www.telepath.com/khobson/odot/liqlab/liqlab.html). The viscosity chart method can give false data for some asphalt cements with polymers. While polymers do need higher temperatures the chart method tends to over estimate.

PS If you can please put a pertinant subject title in the original post. It will help later when we reread these interesting posts in the archives. If you're like me you hit reply and most email programs put the RE: in for you. RE: nothing doesn't help much later. Even worse in replies to replies you get RE: RE: RE: etc.

Kenneth Hobson Bituminous Branch Manager Oklahoma DOT [email protected] 405-522-4918 405-522-0552 fax

Topics covered in this issue include:

1) Mixing and Compaction Temperature by [email protected] 2) Re: Mixing and Compaction Temperature by [email protected]  To: [email protected]  Subject: Mixing and Compaction Temperature

 Date: Mon, 6 Mar 2000 10:05:20 -0600 I was wondering what the difference is in figuring mixing and compaction temperatures would be by using vacumm capillary and kinematic viscosity compared to rotational would be (if any). I have some "old" temperature viscosity charts using the vacuum capillary @60C and kinematic @ 135C. What would be the viscosity ranges for figuring mixing and compaction temperatures? Or, is rotational viscosity the only method commonly used for figuring mixing and compaction temperature?

Thanks for your assistance.

John Dageforde [email protected]  To: [email protected]

 Subject: Re: Mixing and Compaction Temperature

 Date: Mon, 6 Mar 2000 10:39:26 -0600 The kinematic could be used as one point but convert it to absolute. To do that you need to know the asphalt binder specific gravity. You could assume 1 and probably be ok. The 60C is too far from the 135C for a semi-accurate curve. I would adjust the kinematic to run at 145 and or 125C. With two points you could then interpolate a closer result. The closer your points to the actual temperatures will be the more accurate result. With all that being said, the non-linear or 90+ binders will indicate incorrect temperatures for mixing and compaction which are generally significantly higher than need be. You might want to try out my spreadsheet for the 90- binders at http://www.telepath.com/khobson/odot/liqlab/liqlab.html

Mr. Ervin Dukatz seems to have a better method for the 90+ binders. He used a modified DSR method in conjunction with the rotational viscosity which appears to more closely match expected ranges. Maybe Mr. Dukatz will share his method on this forum or he might reply in private email to you. He has always been helpful to me.

Others have done similar techniques to more appropriately estimate the ranges. If we are lucky, and they are on this forum, they might share their technique with us. Even so, the refineries should know their product well enough to recommend the appropriate ranges. This especially applies when they have a long history of performance with their binders.

Kenneth Hobson [email protected] Bituminous Branch OKDOT 405-522-4918 405-522-0552 fax

Topics covered in this issue include: 1) RE: Mixing and Compaction Temperature by "Mathisen, Kim (DOT/SOIL)"  To: "'[email protected]'"

 Subject: RE: Mixing and Compaction Temperature

 From: "Mathisen, Kim (DOT/SOIL)"

 Date: Fri, 10 Mar 2000 09:14:09 -0400 Mixing and compaction ranges are 170 * 20 cSt (mm2/s) & 280 * 30 cSt and 0.17 * 0.02 Pa*s & 0.28 * 0.03 Pa*s which look very similar. The NCHRP 9-10 Project is developing guidelines that can be used for modified and neat binders. They might be based on zero shear viscosity temperatures. ( i.e. - The temperature where the zero shear viscosity is 3.0 Pa*s is your mixing temperature and the temperature where the zero shear viscosity is 6.0 Pa*s is your compaction temperature.)

Kim Mathisen, P.Eng. NBDOT Central Lab Soils and Minerals Building 975 College Hill Road Fredericton, N.B. E3B 4J7 (506)453-8967 phone (506)457-4831 fax [email protected]