ᐅ Foundation bedding gravel, size 0/45 or 0/32, quality grade

Hello everyone,
I have a few questions:
1. Gravel grain size:
We are building with a general contractor (GC). They specified the requirements for the foundation base:
The grain size must not be larger than 0/32 and not smaller than 0/5, with the silt content not exceeding 5%. Ideally, a grain mix of 0/32 size is used. For creating the clean layer under a house with a basement, the use of gravel or crushed stone with a grain size of 8/11 up to 8/22 is recommended.

We are getting a waterproof basement from Glatthaar. According to Glatthaar’s protocol, gravel sizes 0/32 or 0/45 should be used.

Question: How different are 0/45 and 0/32? (Apart from size: one is from 0 up to 45 mm, the other from 0 up to 32 mm)

2. Quality certification: the GC wrote to me:
The required compaction level of the foundation base stated in the geotechnical report must be documented in writing. The legally unambiguous test report must include a statement confirming that the compaction level required in the geotechnical report has been achieved. If it has not, the test report must contain recommendations on how to reach the required compaction level. Afterwards, another compaction test is necessary.

Question:
--> Who carries out such tests? A geotechnical engineer? Have you had such tests done?

3. Gravel quality:
Attached is a picture of the gravel. I have no expertise in this. I have heard that many earthworks contractors use recycled material (or poor quality material), which can cause problems. What do you think of this gravel?

Thank you for your help and have a nice weekend.

Regarding 1) I believe the general contractor will clearly instruct their basement subcontractor on which materials to use.

Regarding 2) I don’t understand. Does the general contractor want proof of the bearing capacity for their own foundation cushion?

Regarding 3) Well, although the picture is missing, I can’t imagine your general contractor would allow inferior materials to be used, especially since they are ultimately responsible to you under the overall warranty.

MayrCh schrieb:

Regarding 1) I think the general contractor will clearly instruct their basement subcontractor on which materials to use.

Regarding 2) I don’t understand. Does the general contractor want proof of the stability of their own foundation layer?

Regarding 3) Well, although the picture is missing, I can’t imagine that your general contractor would install inferior materials, since they are ultimately responsible to you under the overall warranty.

1: I hope so too. Now the two protocols are different.
2: I have removed earthworks afterward (or rather, have to remove them).
3: I forgot to upload the picture.