On Feb 27, 1:26*pm, Derek wrote:
So, can I use retaining wall blocks on concrete? *Do I need to secure
them, or will the weight of the blocks plus gravel inside them keep
them in place?

Just rent an F-ing hammer drill, drill the holes, and anchor with
rebar. It's not that much work, especially with a hammer drill. Two
holes per block, even 40ft, might take you two hours tops. The
retaining blocks already have holes for fiberglass rods that they
normally use to tie the block layers together.

Otherwise the blocks are just going to slide across the concrete.