Hot tar is the old original standby. Current technology demands
cleaning the concrete, installing backer rod to control the shape
of the fill, and careful installation of one of the polyurethane
caulks. Sonneborn's NP1 is a good one, use Vulkem or SL1 if you
want to use self leveling material - your joints need to be fairly
level for these to work, it really does seek level. There are
some excellent 2 part silicone products, but the application
kettles and equipment would not be feasible for a one time use.

--
~~~~~~~~~~~~~~~~~~~~
DanG
Keep the whole world singing . . .


"les" wrote in message
net...
I have a concrete patio that consists of 4 sections, about 10
feet square
each,
and they are slightly shifting to create 1/2" spaces between
them, and the
house
foundation too. (you can't see how far down the crack goes.
seems deep)
I had a tuckpointer here, and he mentioned that besides the work
I
originally
called him about, he could fix this as well.
As you can imagine, constant rainfall and freezing weather
washes away dirt
under
the slabs, so over time I'm afraid this will get worse.
The house (and maybe the slabs) are about 50 years old, and we
live in the
Midwest
over clay soil. There is other evidence of shifting soil around
here.

The tuckpointer said he'd use hot tar to seal things up in
between the
spaces.
I wonder if that's a reasonable fix, or if I could use another
material,
perhaps even
myself, to get a good result.
Would silicon work in this situation? Other sealants?

LB