See the pics below. This appears to be some kind of a seam sealer/buffer between various concrete pads that run up to the house and the foundation concrete. First pic is a closeup, second pic is just a location reference.
The material itself feels like a fiberboard of some kind. Definitely not caulk or other rubberish sealant. It looks like maybe it was placed there prior to pouring the various concrete pads around the house when it was built. Is this maybe for (still new to me) places that get real Winter to maybe buffer expansion and contraction from temp, freezing water, etc.? I have several places where it appears to be breaking apart from age and I figure I should replace it to at least fill in the gaps and keep water intrusion out.
On the other hand, I just had a new patio poured and while they connected it to the foundation with rebar, they just poured right up to the foundation without using this fiberboard or whatever layer. It was a reputable concrete company that gets good reviews, so I have to assume they knew what they were doing.
Anyway, anyone know what this is called and should I try to stuff some more of it in the gaps or maybe use something else?
Note: I just realized dummy me took the reference pic where the new patio was poured, but ignore that. It is only for a visual reference that the area I'm talking about is where the horizontal and vertical concrete surfaces meet.