On 2 Aug 2005 11:27:20 -0700, "bridger" wrote:



I am going to try and replace a broken part of a concrete wall by
jackhammering out the broken stuff and then build a form for the pouring
of new concrete.

Appreciate any help or suggestions


Prometheus wrote:
in your case, that may not be necessary at all- if you're
jackhammering the old stuff out, and there's a rough edge left behind,
that may be enough to hold the new "plug" in place. If you're really
worried about it, you could get a hammer drill, drill some holes all
around the perimeter of the hole, and sink some big lag bolts in so
that they protrude into the cavity, sort of like partial rebar.

code for attaching old concrete to new can in some instances call for
rebar pins epoxied into the old with the new poured around it. the
epoxy is purpose formulated and dispensed in a double-barrel caulking
gun which mixes in the nozzle. it's a bit of a pricey system, but it
works well. the advice to leave a jagged mating surface to the old
concrete wherever you can is good, even to the point of roughing up
smooth surfaces.

Even without the epoxy, rebar pins aren't too easy to get back out
once you've hammered them in, especially if you whack them really good
with a sledge after they're set in the hole (the end will mushroom a
little inside, and act like a masonry anchor) Can work in a pinch if
you don't have the double-barrelled gun.