Rebuild the floor from scratch

I also studied geology – a biologist actually knows nothing about clay. A geologist does.

Nowadays, you often hear about clay from building biologists – building geologists have so far remained hidden from me.

As far as load-bearing capacity is concerned, so not necessarily the floor filling, but rather what the house stands on, the question is indeed legitimate.

Correct. Rammed clay and rammed concrete can also be combined, on average practically resembling damascus blades. Compaction is the refinement in terms of compressive strength, usable for basement floors as well as for foundations. Almost forgotten today and slowly making a comeback, back then (before the era of reinforced concrete) it was traditional construction knowledge, i.e. standard until about 1885 also in the sense of "state of the art." This was generally common in the buildings of the Wilhelminian era.