Recycled crushed stone for floor slab

Yes, it should all be in the statics

In your post you first only write: "just put down a meter of fill sand first"
That’s why my remark that it’s not that simple!

You only write in your post: "first do one meter of filling sand" That's why my note that it's not that simple!

sorry, that was not meant like that. It must be determined individually by an expert either on site or through detailed planning

Basically, recycled gravel is not a problem, but an opportunity to save money. Of course, proper planning is necessary to ensure that everything works out in the end.

In the commercial sector, it is common practice, for example, to demolish old buildings and process them into gravel on site. The gravel is then used for filling.

And in the drinking water protection area, recycling is also usually prohibited. This should also be taken into consideration.

Thanks already for the numerous responses. At first glance, that sounds very good. Firstly, raw materials are reused and secondly, it apparently saves a considerable amount. According to our soil report, the use of recycled gravel is also permitted and should therefore hopefully not be a problem. Of course, it will still be professionally planned on site, so I cannot say too much about it yet. However, since two earthworks contractors we contacted, without knowing the conditions on site, spoke out against recycled gravel, we were a bit surprised.

Assuming the soil report and structural analysis give the green light, is there nothing speaking against the use?

According to our soil survey, the use of recycled gravel is also allowed

It is not the survey that tells you this but the lower (?) water authority, which has to give its approval (for a fee). In this respect, part of the savings is eaten up again. The RCL gravel does not bother me, but it does sometimes come with quite a bit of debris.