Thanks for your thoughts.

Finally got my first asphalt estimate today. $4,950 for the same area.


"HerHusband" wrote in message
...
Still getting estimates on paving the remainder of my driveway.
Latest concrete guy comes in and says they no longer use wire mesh, it
ends up rusting and then popping the concrete, so they mix a fiber
mesh right into the concrete before they pour it. 4 inches.

Wire mesh is primarily used to hold concrete together WHEN it cracks. It
won't prevent cracking. To be effective, the mesh must be placed in the
middle of the slab. Unfortunately, the wire is often layed on the ground
and "pulled up" as the concrete is poured. Obviously, this probably won't
result in accurate placement of the wire mesh. Since you can bend wire
mesh with your fingers, it clearly doesn't add much in the way of
structural strength.

In contrast, fiberglass mesh essentially adds thousands of little bridges
where cracks may occur. Since it is mixed into the concrete, there are no
placement issues like you can have with wire mesh. It won't prevent
cracking either, but it does offer more connections to keep potential
cracks from getting larger.

Rebar provides some crack control like the mesh options, but is typically
used more for reinforcement. Concrete is very strong in compression, but
very weak in tension. If you span a slab of concrete supported only at
the ends, it will break easily in the middle when weight is added (i.e.
driving on it). Rebar adds strength to the slab and allows it to support
more weight across gaps like that without breaking. But it can still
crack from shrinkage and other movement.

I used fibermesh in our 24'x28' garage slab, with no other mesh or
reinforcing. I did not want any control joints in the floor, so it's a
single large slab. It is now 11 years later and there's only a minor
hairline crack near one of the doors. It wouldn't even be noticeable
except for some discoloring where water came in (I have since
waterproofed the slab edge to keep water out). However, we did install
and compact a 4" layer of rock and vapor barrier before having the slab
poured. One thing to consider is the mesh makes it harder to get a
perfectly smooth troweled finish. But this probably isn't an issue for a
driveway.

We used quite a bit of rebar in our foundation footings and stemwalls (as
required by code). This helps strengthen the wall from settling, pressure
from the earth around the foundation, and seismic movements.

I also used a couple lengths of rebar in our sidewalks as these were
placed over backfill around the house. While I tried to compact the earth
as much as possible, there's still a chance the ground could settle. The
rebar should help minimize any cracking if voids develop under the
sidewalk.

For the sake of comparison, my parents poured several concrete parking
slabs and sidewalks with no reinforcement of any kind (no mesh, fiber, or
rebar). As far as I know, those slabs are still intact today with no
problems. Most city sidewalks are poured with no reinforcements either.
So anything you can add to strengthen and reinforce the concrete would be
a bonus.

I'm just an amateur, so consider my advice accordingly...

Anthony Watson
Mountain Software
www.mountain-software.com