ᐅ Layer between ring beam and ridge beam, what is that?

Hello everyone, tomorrow the roof will be installed at our house.
I noticed a strange layer between the wall plate and the reinforced concrete ring beam (?). Is that mortar? It sounded somewhat hollow.

From bottom to top – ring beam -> strange layer -> thick black membrane (roofing felt?) -> wall plate:

Slip layer because concrete and wood expand differently

That was indeed concrete that had protruded over the formwork for height adjustment.

BeHaElJa schrieb:
That was indeed concrete that was visible above the formwork to level the height.

I had advised you to relax 😉

Regards, Bauexperte