I am renovating an old bathroom. It's in a house built in the late 1950s in Germany. I have removed the bathtub. The bathtub was built in a box, which had tiles on the outside and this black material on the inside.
My question is: What is this stuff? Is it asbestos? I need to know, because if it really is asbestic-material I cannot dispose it along with the "normal" debries.