SUPERPAVE Digest 309

Topics covered in this issue include:

2) AASHTO TP57

by

3) Re: AASHTO TP57

by "Ervin Dukatz" <>

5) Re: AASHTO TP57

by

6) RE: AASHTO TP57

by "King, Gayle" <>

  • To:
  • Subject: AASHTO TP57
  • From:
  • Date: Tue, 25 Jan 2000 11:54:19 -0600

This is the Standard Test Method for Methylene Blue Value of Clays, Mineral

Fillers, and Fines.

I was wondering what other states are using this test procedure and how they

implement it. Is it used for both Marshall and Superpave? Is it an

augmentation to AASHTO T 283 in some cases? Did you relate it to the Sand

Equivalent test AASHTO T 176 in any way?

Kenneth Hobson

Bituminous Branch OKDOT

  • To: <
  • Subject: Re: AASHTO TP57
  • From: "Ervin Dukatz" <
  • Date: Tue, 25 Jan 2000 14:08:44 -0600

The ASTM version is currently being ballotted in subcommittee D4.51 as a forensic test. The methylene blue test has been used for many years as a test for mineral filler activity in microsurfacing mix designs. I am not familar with any research that would indicate its use as a substiute for T283. Since it measures the absorption capacity of the fines it may correlate with sand equivalent for some clays. So would be a good test to run with T 176 to better understand a sample.

Erv

  • To:
  • Subject: Re: AASHTO TP57
  • From:
  • Date: Tue, 25 Jan 2000 15:05:37 -0600

Mr. Dukatz, thanks for your comments as always.

The AAPT article I was referring to was in the 1998 Vol. 67, "Tests for Plastic

Fines in Aggregates Related to Stripping in Asphalt Paving Mixtures", Prithivi

S. Kandhal, Cynthia Y. Lynn and Frazier Parker, Pg. 233.

They used the Methylene Blue Test which was a French test method recommended by

the International Slurry Seal Association (ISSA) to qualify the amount of

harmful clays of the smectite (montmorillinite) group, organic matter and iron

hydroxides present in fine aggregates. The test method titled "Determination of

Methylene Blue Adsorption Value (MBV) of Mineral Aggregate Fillers and Fines"

was contained in the Technical Bulletin 145 of ISSA. Was this not where the

AASHTO TP57 evolved from?

I thought it was an interesting paper at the time and was hoping that it could

be of value to us in the industry. Seems like an earlier paper supported using

this test in lieu of or in conjunction with the sand equivalent test. I could

be wrong about that. Irregardless, my interest is in its usage as a stripping

indicator. The results would be more easly obtained than AASHTO T 283.

Naturally, this Methylene Blue Test is only an aggregate test. The AASHTO T 283

is more of an end product testing which could have addtives to enhance retained

strength properties. I suppose the lime might help in this test or not since it

may act as a filler. This still would not account for chemical additives.

As some of you may know, we sent a survey to the 47 other continuous State

Material Engineers. The title of the survey was "Stripping Problems in

Bituminous Mixtures Survey". I have received 27 responses so far. I'll

probably post the results on my

site in a week or so.

We are investigating why we had so many retained strength failures this past

year in the mix design phase. One theory was that the PG binder system traded

off the chemical reactivity that helps retained strength. I'll probably post

our final conclusions after we complete our round robin testing by our Retained

Strength Task Force members.

Kenneth Hobson

Bituminous Branch OKDOT

  • To: "''" <
  • Subject: RE: AASHTO TP57
  • From: "King, Gayle" <
  • Date: Tue, 25 Jan 2000 16:50:32 -0600

The methylene blue test is fairly commonly used in France and Germany. One

important application is as a qualifier test for SMA fillers.

Tim Aschenbrenner visited Europe while setting up the CDOT Eurolab, and has

an excellent perspective on the use of Methylene Blue there. Tim also

published some very interesting work using the Methylene Blue test as a

forensic tool. As one example (as best I recall), he noticed severe

moisture damage during a Hamburg wheel-tracking test when evaluating an

aggregate from a pit that had experienced sporadic pavement stripping

failures. He then used Methylene Blue to track the problem to one area of

the pit, where they found very fine clay seams in the rock ledge. Even

though the overburden was long removed, the aggregate naturally fractured

along these weak seams, exposing enough clay to create serious moisture

problems. It would be interesting to see if the sand equivalent test with

current specification limits would fail such materials.