VDOT: Asphalt Field Compaction Testing

[QCTechnician]

Using the Marshall Method, what is the desired % compaction for BM.25 base course aspahlt? There are numerous ways to test asphalt in the field, we generally use the Roller Pass/Constrol Strip method and secondly we use the Rice Value in determining the in-place density. However, sometimes our project specs call out the Marshall Method, but they leave the compaction requirements blank.
any help would be appreciated.
Thanks

 

[Rjeffery]

If I remember correctly, In Virginias' "Road and Bridge Specification" they reference "Maximum Theoretical Density" which is what the Marshal test is use to produce. In that book there is a paragraph (I don't have my copy with me) that states that is your reading fall within (say) 92.5 and 97.5% of the MTD that the asphalt as placed is acceptable. But... Unless your project is small enough that a Roller Pattern/Control Strip is not feasable, do the RP/CS. if not default to MTD

 

[QCTechnician]

Max Theoretical density is the Rice Density.
Marshall is the laboratory density.
For the Rice value it is 91.5%.
This is were the confussion lies.

 

[BigH]

You are correct that the MTD is the Rice Density. I'll have to look up my stuff at home - had the same problem in India. Our compaction required 98% Marshall minimum (which caused a lot of flushing and other problems during secondary compaction) but most "international" specs seemed to be written to the Rice Density. If I remember correctly, we should have been compacting to about 96% Marshall Density. I figured that the 100% Rice was about 104%(+/-) Marshall so if you are compacting to 92% Rice, it would be about 95.7 - or 95% to 96% Marshall.