Concrete floor caulking is failing... why and how to fix?

[cavendum.e...@gmail.com]

My polished concrete floors are about a year old. Now I see that the caulking the flooring contractor laid in the seams is starting to crack and split (see photo... the seam is about 3/16ths inch across). The splitting appears to be occurring more often in the part of the floor that gets sunshine.

Anyone know why this is failing? What's the fix?

Thanks.

C