Have you ever used solar reflective

[Okiryu]

Have you ever used solar reflective coating in flexible pavements? If so, can you provide any references for this type of materials? I google it and appears that solar reflective coatings are used mainly in roofs. I didn't find good references for pavements. Thanks !

 

[eea]

Never heard of it. Are you trying to pick up some LEED credits for pavement to reduce asphalt's heat island effect?

 

[Okiryu]

Yes...this is for LEED credits...

 

[epoxybot]

Perhaps you have already seen this page from Berkeley Lab Link
The consensus seems to be that a flexible pavement, aka asphalt, attains the best albedo when the finish is a chip-seal coarse that takes advantage of whatever light reflecting properties the aggregate possess.

The only other flexible pavement binder produced in any volume and nothing approaching asphalt, is the polyester used for making polyester concrete. I believe the SF-Oakland Bay Bridge was re-paved with polyester concrete. There might be some albedo figures available from the Caltrans lab. Polyester concrete uses about twice the binder content compared to asphalt, so the change might not be as great as hoped for.

 

[IRstuff]

Note that tar roofs have traditionally had embedded gravel to protect the tar from deteriorating in sunlight. I'd be concerned as a driver whether chip seals would unduly wear my car tires though

There are commercial applications of chip seal on roadways:

http://asphaltmagazine.com/improving-chip-seal-performance/

http://unitedpavinginc.com/chip-seal/

http://www.dot.ca.gov/hq/maint/MTAGChapter7-ChipSeals.pdf

http://www.webpages.uidaho.edu/bayo.../7. Chip Seal Best Practices, Quint Davis.pdf

https://www.epa.gov/sites/production/files/2015-10/documents/2003_07_24_nps_gravelroads_appd_0.pdf

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[Okiryu]

Thanks guys. Very helpful.

 

[eea]

I don't know that I would seal coat a new asphalt parking lot just for a LEED credit.

Working through the cost of concrete versus asphalt on new construction and you'll likely find that concrete is currently competitive to asphalt paving. We've recently bid (and constructed) two different multi-use paths with an asphalt "base bid" (3" HMA on 6" of Agg) and a concrete "alternate bid" (5" conc on improved subbase) and had concrete win both times. These were each 1 mile segments at 8 foot wide x 5 inches thick that were slipformed.

Rehab'ing an existing asphalt lot, I would certainly look at the seal coating with a "cool color" to pull it all together and maybe score the LEED credit.

 

[ACtrafficengr]

Would thin white-topping be an option?

This source is a bit dated, but it might help: NCHRP Synthesis 338: Thin and Ultrathin Whitetopping

 

[epoxybot]

This is a really nice publication for explaining Albedo and building materials in general. Link

 

[epoxybot]

Okay, here is an interesting possibility. Ultra Thin Asphalt Overlays, AKA NovaChip using Shell Mexaphalt-C Link

Datasheet: Link

 

[Okiryu]

Thanks for the good references. For our last projects, there are requirements to be “environment friendly“ so these type of materials have been required in the specs. One of the contractors used a product in a parking lot which peeled off under heavy traffic so I was wondering if these are appropriate materials for pavements. Thanks again!

 

[chicopee]

From ACtrafficengr "Would thin white-topping be an option? This is particularly a good option if the coating was resistive to traffic on flexible pavment. If anyone knows or is familiar with the Moroccan city Casablanca, meaning white houses, the white color on these houses have reflective property from the sun.

 

[ACtrafficengr]

Okiryu, Would Portland cement blended with fly ash or silica fume qualify, since it uses waste products to make the concrete stronger?

 

[Okiryu]

The site that I saw this coating failing was a flexible pavement. I guess that rigid pavements may not require these coatings because they are not “black”?