Middelheim museum in Antwerp houses an extended collection of the 20th century sculpture. I was curious how many concrete pieces they have. There were some objects that looked like concrete but when I came closer and touched them and scratched them gently with my nail, and knocked lightly with my knuckles, they turned out to be metal or natural stone. I managed to identify only four (!) concrete pieces and was absolutely sure but 2 out of four were 'granite stone' according to internet catalogue. Couldn't believe my eyes.
Granite stone 'Column pavilions' by Charles Vandenhove
The concrete piece by Marta Colvin.
Bernard Heiliger's figures are made of fiber reinforced concrete.
Some of the sculptures have this rough 'concrete" look. The limestone Female Rock is by Fritz Wotruba.