Not suitable for cement blocks. I ordered this because I couldn't find the Loctite glue I've used in the past. This thing was as useful as chewing gum. I was able to pull the blocks apart by hand with minimal effort, and that was for a tree ring about 6 blocks tall. Luckily I found Loctite and did about 2/3 of the project with it. I went back and reapplied Loctite to the top blocks originally made with this product. Don't waste your time and money.