3/4" Dolomite 2

To meet AASHTO #57, 25-60% of the sample must pass the 1/2" sieve, and must 100% must pass the 1 1/2". There is no criteria for 57 stone relative to 3/4" sieve.

Well Graded is a USC subclassification relating to the uniformity of the sample; it does not specify a diameter.

Have the contractor supply a certified bill of lading ("ticket") for the delivery. If the d50 is not 3/4" you can turn it down. If it is 3/4", you can't.

WhiteLotus:

Is there a reason to specify the 3/4" dolomite vs a well graded stone?

Thank you lha! Thats what I was hoping for. The documentation they submitted doesn't contain a D50 value. It simply states "ASTM 57" and the source location in the description field.

I am not familiar with ASTM 57...make sure it does not mean 3/4" stone. If it does mean 3/4" stone, I would not turn it back, unless I could prove it doesn't meet that standard.

WhiteLotus - I think this is a case, and many of us need to sit back and think, where a bit clearer indication of what you really wanted should have been clarified in the specs. If you wanted 3/4" clear stone (i.e., single size) why not have specified that? It is always better to give a specific definition (with gradations, atterbergs, AIV or LA Abrasion, etc.) when putting into specs and this will minimize problems. I see far too often the use of earth fill, soil fill, etc. Not very technical - and clearly not clear in its meaning.

Jheidt - Well graded is prefered. Single size crushed stone just isn't as easy to walk/drive on as a well graded mix.

lha - Your AASHTO #57 descirption is dead on with the ASTM 57 description I have.

BigH - You are absolutely right!! At my company, we have standard boilerplate specifications for certain jobs/mateirals/etc. that we refer to when preparing a new spec. When I was writing this specification two years ago, I was more concerned with the details of the concrete and steel portions of the job than I was with the grading. Not to trivialize it, but dolomite was the absolute least of my worries.

Looking over some old specs involving dolomite, with the exception of one project, all specifications simply required " 3/4" Dolomite". I guess we've just been lucky all these years. Either that, or consistently duped. Either way its not something i'll leave to chance in the future.

Thanks to all for your assistance

WhiteLotus...your specification was not "specific". In many areas, a No. 57 stone is considered to be a nominal 3/4" material. Yes, it's top size is more on the order of 1", but the predominance of material will be in the 3/4" and smaller size.

As BigH said, why not specify what you want? There's no reason to be vague in a specification unless you don't know what you want or need, in which case you shouldn't be specifying it without some help. Further, don't specify something without knowing the parameters. If you specify a No.57 stone, it should be properly specified to comply with ASTM C33, Gradation 57. This incorporates more than just the size range of the gradation....it incorporates durability and reactivity issues as well. If you want a well-graded material, then specify according the the Unified Classification System or some other accepted engineering classification criteria for aggregate or soil (in your case you apparently wanted a GW, with max. size 3/4").

What you specified is not clearly rejectable. I would argue that you were unclear and that the contractor met the generally understood criteria of a "near 3/4" stone commonly used for your application. You'd be hard pressed to refute it without a better specification.

Another point is what is availble in your area. Some areas will sell #57, some will sell 3/4" others will sell by local DOT Spec No. It depends a lot on how the DOT, Highway Authority or county specifies it stone requirements. If you want something different than what is commonly available, You will pay big bucks. Generally it is not worth it for small differences in size. Call a few suppliers and match the specs to what is readily availble locally.