Gravel may be natural or manmade and is usually round rather than angular ( although it may be either ).
Granular fill is usually manmade crushed rock so it is almost always angular and may include some sand and even some small amount of silt sized particles.
At least in my experience. Others may have a different view of this.
Granular fill can include sands, gravels and cobbles, even boulders. In my area, it usually means a sand/gravel mixture. It's a material where the individual grains can be observed without the aid of a magnifier or microscope.
Actually, I have found that those two terms are quite often interchanged and it depends on the context and person whom you are speaking with where the meaning can differ. Granular, for me, has always meant a graded aggregate (crushed rock/sand or graded pit run).
To a councillor, public or (sometimes) contractor, gravel is usually the surfacing aggregate placed on the completed grade (rural road x-section). To a road builder or engineer or inspector, gravel is screened, uncrushed aggregate (ie. raw gravels out of a stream bed or pit run out of a bank run through a grizzly). Granular has been processed to a specified specification. KRS Services
MAG specs define "Granular Material" as follows:
For the purposes of this specification, Granular Material shall meet the following requirements:
1. Material shall not contain any pieces larger than 1 ½ inches and shall be free of broken concrete, broken pavement, wood or other deleterious material
2. The sum of the plasticity index and the percent of the material passing a No. 200 sieve shall not exceed 23.
3. Plasticity Index of the Material as tested in accordance with AASHTO T 146, Method A shall be less than 5
4. Open graded rock or gravel shall not be used.
I think this all depends on which country you are in. In the UK granular fill is generally any material with less than 15% CLAY and SILT fraction, i.e. less than 15% passing the 63µm. The GRAVEL sized fraction on the other hand is a general descriptive term used for material which is finer than 63mm and retained on a 2.00mm sieve, which could include natural rounded gravels, crushed rocks or even secondary re-cycled materials such as crushed concrete. Natural gravels tend to be used as a descriptive term for a weathered rock mass which has formed a smaller fraction within the 63mm to 2.00mm size, and are generally rounded to sub-rounded pieces, with the parent rock geology falling into one of the primary rock sources, i.e. Ingeous, Metamorphic or Sedimentary.
