First, you've got clumpers and I think they will expand slowly until they get to the concrete border, and then flatten up against it. I can't guarantee it won't break it, but I doubt it. I did see a very large clump oif Alphonse Karr a couple of years ago that was in a planting strip about 2' wide: on one side was a building with a concrete foundation and on the other side was a sidewalk. The clump was obviously quite old, the planting strip had pretty much filled up, and the root ball had sort of bulged up a little at the edge of the sidewalk...but it didn't go further or damage the concrete. Now I know that a cement border is different from a sidewalk, but I am still of the opinion that you'll be ok.

As for the edgers you laid down, they won't weaken the bamboo, but I don't think they'll do anything to prevent growth. Over time, the bamboo will probably just push up the pavers.

You have a big advantage over those of us who grow runners: you know that you are not going to get culms coming up feet away from the rootball, and whatever the plant does in terms of growth will be slow. If, in some future year, the bamboo looks like it is starting to crack the border, you can just cut out a portion of the root ball and culms on that side of the clump. It will be hard work, but it's not like you'll wake up some day and be surprised about what's happening.