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friction angle of road base materials

friction angle of road base materials

friction angle of road base materials

i am looking for a source providing friction angle of road base materials ( typically Mulch gravelly sand 19 mm compacted to 95 % modified proctor destiny ). i am assuming that we are talking above 40 degree as a minimum ?
Thank you

RE: friction angle of road base materials

Usually, road base material is well-graded crushed stone. 40 degrees is probably a nominal phi angle for that type of material. We typically use 34 degrees as a conservative design value.

RE: friction angle of road base materials

For a Type 1 road base, as defined in the UK, (similar to HRs, well graded crushed) I would be comfortable giving a phi of 38 degrees. Thats assuming you have all the documentation to confirm its been placed, compacted to a good spec. But if you had all the documentation you probably would have a shear box test result....

RE: friction angle of road base materials

As a peak friction angle 40 degrees is probably low, as a residual friction angle 34.

A lot of us dot organizations post values and testing results.

RE: friction angle of road base materials

dense-graded aggregate would be easily 44 degrees. Open-graded aggregate at least as good.

Regarding the dense-graded aggregate, the FHWA did do some checking on this for their GRS-IBS bridge system design.


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