Is there asbestos in the roller shutter box?

Hello,
you helped me so quickly with the last question (thank you for that). Same window, I have now wanted to dismantle the roller shutter box. The corresponding room is an extension from the 1970s. This attached roller shutter box protrudes slightly into the room. I had always assumed that the part protruding into the room was made of wood. Unfortunately, it seems to be a solid building material; at first, I suspected concrete. During today’s dismantling of the wooden frame and removal of the roller shutter, I became a bit skeptical. The wooden frame was nailed in. When pulling out the nails, the building material chipped off. It turned out to be very black, relatively light, and very brittle. Originally, I wanted to saw off or chisel off the parts protruding into the room. But now I am cautious. Maybe you can already tell from the photos whether asbestos was used. Unfortunately, there are two more identical roller shutter boxes in this extension, whose doors/windows are to be preserved in modernized form. Here too, the parts protruding into the room must be broken off or sawed off...

Therefore, the question now is whether asbestos might possibly have been used. Since the appearance seems very characteristic, an expert might be able to say something based on the pictures.

Thanks for any help.

hbergmann

This is a precast lintel - at least ours look like this, which were installed when the roller shutters were mounted in the 70s. Why should there be asbestos in it?