Max. thickness for AC pavement layer

[Okiryu]

Hi, do you have any references about the maximum thickness of the Asphalt-cement layer for flexible pavements? Is it based on the size of the aggregates? Thanks !!

 

[Ron]

The minimum thickness of an asphalt layer is affected by the aggregate size more so than the maximum thickness. In general, the layer should be at least 2 to 3 times the maximum nominal aggregate size.

While there is no true limitation on total maximum thickness of asphalt, it is limited by cost. We try to optimize the design to reduce the total asphalt thickness for cost savings.

For constructability, each layer of asphalt placed is usually limited to a maximum of 3 inches at a time so that the mat does not cool too quickly and compaction to its full thickness can be achieved without shoving and stretching the asphalt during placement.

 

[Okiryu]

Thanks Ron. That is helpful.

 

[BridgeEI]

Around my parts the thickness is limited by the contractors abilities. The majority can't get a quality project if they do lifts of 4-6" so we limit the lifts to 3.5" at the maximum. No reference here, just a constructability issue.

 

[Okiryu]

Thanks. I will consider 3in as the max lift thickness.

 

[jgailla]

I've limited lifts to 2" in the past, although this is probably conservative. This is when dealing with site contractors, not experienced paving contractors.

 

[Okiryu]

Problem is that for design-bid-build projects you do not know who the contractor will be...