http://www.google.de/search?hl=en&q=%22concre...

http://www.google.de/search?hl=en&q=concrete+...

... even as a non-native I'd think that "concrete" as "konkret" is fairly common.

Noun

* S: (n) concrete (a strong hard building material composed of sand and gravel and cement and water)

Verb

* S: (v) concrete (cover with cement) "concrete the walls"
* S: (v) concrete (form into a solid mass; coalesce)

Adjective

* S: (adj) concrete (capable of being perceived by the senses; not abstract or imaginary) "concrete objects such as trees"
* S: (adj) concrete (formed by the coalescence of particles)

http://wordnet.princeton.edu/perl/webwn?s=concrete


So do I.

thanks a lot to weißnix & penguin - that's why we all love Leo ;o)

Would you say, "concrete activities" works? It does not sound quite right to me but if a native speaker things it works, I be less concerned about it.

"Betonhobbies"? SCNR
I'd rather say "specific activities".

"concrete activities" sounds fine to me. It indicates that the activities are well-defined, and presumably, well-suited to the overall purpose.

Must say I agree with Bama, 'specific activities' is what I would choose.