how do i bond a new concrete blockwall to a existing wall .?
Answers:
Depends. You don't state if the existing wall is poured concrete or if it is cement block or if it is core-filled cement block.
If it is a hollow cement block then I would suggest what an earlier poster did, with one exception. Break out the fronts of some of the cement blocks and break out the backs of some of the new blocks before you put them in place. After it is done, core fill them both.
Otherwise, if it is a solid poured wall or a core filled wall, get a hammer drill and drill holes in it about 5" deep. Buy a cement epoxy and glue rebar into the holes. Build new wall around the rebar and core fill.
Other answers:
Break out a section of the other block wall put the new block in the place of the old.
Break out a section of the other block wall put the new block in the place of the old.
Chip and roughen the section of wall you are bonding to. Then drill some holes in it so you can set some galvanized pins for total support.
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