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11-11-12 | 04:02 PM

#17

michaelcycle

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Joined: Nov 2012

Posts: 5

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Chip seal will often be applied to the full width of theroadway to ensure that the entire surface is waterproofed. It is a case by casedecision. The shoulder may not show visible wear or cracking, but an oldoxidized asphalt will allow water to penetrate. It is essential to preventwater penetration into the subgrade to prolong life. Pavement deteriorationoften starts at the edge and works its way in. I'm sure you've driven roadswith a steep drop off at the edge of pavement. Sealing shoulders is a long termstrategy to prevent these dangerous edge conditions.

All a chip seal does is waterproof, that's the goal. Thereis little or no structural improvement. To improve the structure, a hot mixpavement would have to be constructed. So, imagine a road with an overall widthof 32' (12' lanes, 4' shoulders) with an oxidized surface, minor crackingthroughout, and some minor rutting and cracking in the wheel path. A commonsolution is to chip seal the entire roadbed (32') to provide waterproofing andthen overlay the driving lanes (24') to address rutting/cracking. Pretty goodsolution, and you'll see it all over the state. Driving lanes end up smoothbecause they needed structural enhancement. Shoulders end up with chip sealbecause they don't need more pavement structure, they need waterproofing.

That’s the basic thought process.

This is a very old report, but may be what you are lookingfor:
http://library.ctr.utexas.edu/digitized/TexasArchive/thdresearch/133-3F_TxDOT.pdf

Search for transportation research here:
(keyword search for “surface texture safety” or similar)
http://library.ctr.utexas.edu/dbtw-wpd/textbase/websearchcat.htm
http://tti.tamu.edu/research/
http://www.trb.org/Main/Home.aspx

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