Asphalt Compaction 1

[BigH]

I'm requesting my esteemed colleagues to provide me some details of compaction requirements for base asphalt and wearing course in your state, province, country. For example, some jurisdictions use 96% Marshall compaction of Marshall 75 blows. Others use 98% Marshall compaction at 75 blows. I am looking for national highways, major state highways (e.g., US40, US20, I-75). Added information if your specs call for it as to % air voids or % voids filled with aspahlt at primary compaction would be useful. I am looking mainly to dense graded mixes, not open graded. Thanks to all.

 

[dicksewerrat]

Go to the website for the DOT for the you are working in. They will have a spec for their state. Each state may be different.

 

[SirAl]

Hi BigH.

http://www.trans.gov.ab.ca/Content/doctype245/production/Specs2003.pdf

I hope this long thread works. Go to Section 3.50. The various mix types are a function of design ESALs. Oil grade selection is also a function of ESAL's as well as climatic conditions. Some guidance in selecting the mix type and oil type specific to the above reference might be found at the following link:

http://www.trans.gov.ab.ca/Content/doctype233/production/pavedm2.pdf

I hope this helps. Compaction for this jurisdiction is 97% Marshall with pentalties and bonuses applied to lower and higher field compaction. You will find all applicable mix parameter specs at the first link site. Superpave specs are also available.

 

[boo1]

The National Highway Specifications website (NHSW):

http://fhwapap04.fhwa.dot.gov/nhswp/index.jsp

This site consists of a searchable library of highway specifications from across the United States of America. The site also features Discussion Forums to enhance communication and interaction in the development and use of various types of construction specifications.

 

[BigH]

Trouble is that I do not have highspeed connection and our server is cutting us off every 10 minutes now (when we have electricity) - was hoping for the something along the last part of SirAl's post - 97%, etc. But, thanks for the head-ups.

 

[shppo]

Mississippi DOT requires density between 92% and 95% of maximum density (AASHTO T 209)(which I believe most state agencies specify) for dense graded courses. How do you correlate maximum density determined using AASHTO T 209 vs. Marshall (75 blows) compaction density. FAA specs require 96.3% (minimum) Marshall compaction, not for highway use though.

 

[cvg]

Maricopa Association of Governments - City of Phoenix urban area - Arizona

95% - ASTM D-1559 - 75 blows
or
93% - ASTM D-2041 for Asphalt Int. SP-2 Gyratory method design

Reductions in payment for insufficient density if more than 1% low

 

[dirtdoctor]

If field measured by obtaining cores, SCDOT specifies 91.6% to 96% of Rice (theoretical max) gravity. Older specs were compared to Marshall results, as the FAA still does.

I do not like comparisons to Marshall results - what if Marshall SG is low and compaction is poor in field - you still would get a good value for %compaction versus a lower Marshall value, but would most likely be upwards of 9% to 11% airvoids (when compared to Rice values). A spec with percent compaction based on Marshall values should also be accompanied by specs for %VMA or %voids filled in order to ensure that a good mix is being placed. This can be a real problem when producer makes a fine and dry mix (the cheapest kind to make). Just my $0.02 worth - after working both sides of the fence (producer and tester).

 

[BigH]

Dirtdoctor - wish we could talk. Problem: the specs call for compaction of 98% of Lab Marshall and contractor gets price reductions for each 1% below 98% (e.g., -5% for 97-98; -15% for 96-97, -35% for 95-96, nothing). Of course, contractor will always get 99% - his target for he doesn't want to lose any money. We have 3-5% AV at Marshall, 65-75 VFB (VFA) also in specs. We also have 4.5% minimum asphalt and our coarse aggregate has SG of 3. So, at primary compaction he is packing it down to about 4% AV so with secondary compaction, this will drop to below 2% in some cases. I think compaction is too high; also 4.5% is too high and we are getting flushing at surface on secondary compaction - also, I think that the paver set-up is off leaving a scrapings of fines at surface. So, ????

 

[dirtdoctor]

Big H -

Sounds like your client has the same specifier as one of our big box boys (the home improvement store that's not orange in color). Their spec says that contractor shall compact mix until 96% of Rice is achieved. If contractor does this, he/she has already killed all the voids that normally would consolidate over the pavement life cycle. Kind of hard not to expect some shoving, rutting, etc. if one tried to get 96% of Rice. As far as flushing of the binder, if such a high spec is required, specifier has to know that if you compact it so hard that binder 'leaks out', something has to be wrong. I'm sure you've already told him/her this, but the pavement can expect to become rutted very soon, particularly if any heavy truck loads are applied. Soon after the rutting, I'll bet it starts to slide and pop open, thus causing shrinkage cracks followed by the evil POTHOLE (run away!!!).

Although my call name is dirtdoctor, my first love is the hot black stuff. Scraping of fines at surface - sounds like contractor has fined up mix a tad or else the rubber tire roller is not hot enough to keep from picking up the fines in the mix.

The glory days of pavement will arrive in the US soon, as Stone Mastic (or Matrix) Asphalt will become a reality. The Europeans (particularly Germany) have been using it for years, with much success. After Georgia DOT bit the bullet and put it down on I-85 (perhaps the one stretch of pavement in the US to see the harshest conditions - heat, heavy truck loads, along with freeze-thaw cycles) around Hotlanta, the pavement guys around here could be seen smiling from ear to ear. The stuff is great, but be prepared to spend some cabbage to buy it.

 

[KRSServices]

SirAL,

You're in Alberta, I am as well. Where are you located? If you are with the Province in Barrhead or Twin Atria, chances are we have met on occasion.

Cheers

KRS Services

http://www.krs-services.com

 

[BigH]

dirtdoctor aka blackstuffguy -

 

[gatorn10ac]

If you'll go to the ASHTO web site that should give you some insite about asphalt.

 

[SirAl]

Hi KRS Services

Thanks for the greeting. I am a consultant although we have undertaken a significant amount of design and QA work on rehabilitation, reconstruction, and new construction projects over the years with the Province and various municipalities. I'm currently stationed in GP. Hope to see you sometime.