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The Importance of Asphalt Thickness

asphalt thickness
Asphalt thickness is one of the most important factors that determine how a parking lot performs.  While this may be true, there are numerous parking lots that are paved with less than adequate asphalt thickness.  This sad truth requires some questions to be answered:

How does thin asphalt happen?

There are many situations which occur where the asphalt thickness is less than it should be.  However, the two most common situations are; poor design & contractor dishonesty. The first situation is probably the most common and is pretty self-explanatory.  Yet, the second situation posed is a scary scenario for a buyer.  While I’d love to pretend that this type of thing does not occur in the asphalt industry, or even in the contracting community, that would be wishful thinking.

Buyer Beware!

Paving asphalt that is thinner than what was quoted is the easiest way an asphalt contractor can increase their profit.  This is done at the expense of a trusting buyer that thought they were getting a great deal.  Common sense tells us, “If it is too good to be true it probably is.”

How do you know you are getting what you paid for?

This is the age-old question!  Most people that hire an asphalt contractor may think they can watch the asphalt being installed and verify they are getting the asphalt thickness they paid for.  This approach may seem to be the solution.  However; this is very tricky! Asphalt thickness is hard to determine while being installed because it comes out of the back of a paver thicker than the finished product.  Further, once the surface is paved one cannot see what’s underneath. There are really only two ways to determine asphalt thickness.

-Calculate the estimated tonnage, collect truck tickets and compare.
-Extract an asphalt core upon completion of the project.

Tips to follow:

-Pay attention to the language used on a proposal.  If it reads, “Machine-lay asphalt at X inches”, this should be a red flag that the compacted product will not be what is desired
-Before signing a contract, ask the contractor how many tons of asphalt he/she calculated and compare with others
-Ask the contractor if they would feel comfortable if you collected truck tickets or core an area

What determines appropriate asphalt thickness?

The main factors that determine asphalt thickness are:

-How frequent the area is traveled
-The average weight of a load that travels the area
-The type of asphalt used
-The conditions of the existing sub grade

To shed some light on this, view the thickness design section in The Wisconsin Asphalt Pavement Association’s Design Guide


Asphalt thickness is crucial to the life cycle of an asphalt pavement section.  It is also the easiest corner a contractor can cut because it is difficult to determine.  Avoid getting ripped off and follow the tips above.  An honest contractor should have no hesitation in providing you with the information you request.


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