Design of Asphalt Pavement without Subbase

[Blackfairy]

Hi, I am looking online and cannot find an answer or direction. I am from California and use Caltrans Road Design. How do I design a pavement without a subbase? I am designing an access road that will really only have at most 2-3 HS-10 trucks on it daily. My coworker said with that low traffic I can just forgo the subbase, but I cannot find a way to design it. Do I just design it as it has HMA, Base, Subbase, get thickness of each and just eliminate the subbase in the end?

I know it will depend on the subgrade but I will still have to get soil samples. Another question is how to determine if it is strong enough? Get California R value? i doubt it will be as strong as a subbase R value. I know they need to be well compacted and draining too. Get California Bearing Ratio (CBR) i guess. Though I am new and still needs to learn how to utilize it.

 

[dik]

The subbase is part of the asphalt pavement system and contributes to the strength. Without it (I'm not sure you can) you would require a greater thickness in asphalt at a greater cost. I don't design asphalt pavements.

 

[jhnblgr]

money in the subbase is best unless the existing material is gravel or stone to start with. A poor subbase will result in long term maintenance issues. Asphalt is prone to ruts, really should be seen as a wearing surface.

 

[IRstuff]

Seems like a dubious proposition; even roads with subbases get pretty beat up with heavy vehicle traffic.

One can simply compare the right lane vs. left lane on I5 in the Central Valley to see the difference in what heavy trucks do to a fully compliant roadway.