Change of ac-14 tob AC-20

[msesi]

I'm currently working on asphalt concrete road(AC-14).The Contractor wants to change from AC-14 to AC-20 stating the 14mm aggregates are too small compared to the heavy traffic expected to pass on the road.I can I allow him to make such changs???

 

[Ron]

The size of the coarse aggregate (within reason) has little to do with the structural capability of an asphalt layer.

Before you allow, make sure that the thickness of the asphalt layer to be placed is at least 2-1/2 times the nominal coarse aggregate size.

Both aggregate sizes are commonly used for high traffic application, though the 20mm aggregate will likely perform better for the long term, assuming the mix is properly designed for voids, AC content, etc.