Not completely off-topic since this driveway connects the gar-shop to the
As the final part of a new addition to our house, we will need to install a
new driveway. The existing driveway is about 100 feet long and 10 feet
wide. It appears that once upon a time, it existed as a concrete driveway.
I'd say it has been resurfaced twice with asphalt. (House is 50+ years
old). The new driveway will be about the same length, but gets moved over 5
feet or so. The approach to what will be the new gar-shop will be somewhat
different as well.
a) How difficult would it be to demo the existing driveway? My dad has a
combination (and a bulldozer) that we could use, and I suppose we could rent
anything else that might be desirable. My guess is removing the asphalt
will be simple...perhaps as easy as putting the bucket of the combo down and
scooping it up. My big worry is the concrete. I don't know how they were
building concrete driveways 50 years ago. If we're talking concrete
reinforced with rebar, I think we could have a job on our hands. If, OTOH,
it was not reinforced, it might not be as bad. Obviously, no one knows what
conditions exist, so take your best WAG.
b). Once the old stuff is gone, would I be nuts to try to pour this myself?
Honestly, I've never poured anything this large. However, the old man has
and he's got other friends who have also. Of course, after the old driveway
was demo'd, the new driveway base would have to be prepared before we could
form up for the new driveway.
I'm looking for opinions from people who have poured large slabs. If you
think I'd be stupid to attempt it, that's a fair opinion. I'm wondering
about it myself.
Yep, you have a nice tough job ahead of you, but I think you can do it
if you have some help handy. The existing concrete may not be 4"
thick. It may be 2&1/2" to 3" and not have reinforcement wire or bars.
A 4" existing slab would be about 12.5 yds of debris to dig out, plus
the asphalt. Is the old slab deep enough for you to pour the new drive
on top of it. The old slab is a good foundation, already compacted.
What is your conditions, such that, cutting half the slab (the length)
for removal, and leaving the other half for foundation? .... Use the
concrete debris, of the half you demo, to prep the bed of the other new
half, hence you wouldn't have to haul it off. Is this feasible for you?
Any dirt dug out for the new area can be used to refill the dug-out
part of the old area. As for as using old concrete debris as prep
foundation, if it's small enough chunks, the dozer can be used to
compact it well enough, I would think.
A normal drive is 4" thick, or about 12.5 yds of concrete. Pouring a
6" slab is about 18.5 yds or about $600 more for a 6" slab (concrete is
about $100 per yd here, these days). Can your circumstances
accommodate a 6" slab? That thick of slab would be less likely to
crack under pressure, as compared to a thinner slab, of course. Get at
least a 3000 psi mix, not the normal 2500 psi mix for driveways. Pour
a 12" X 12" footing at the road and also at your garage, to prevent
cracking at those junctures. Place expansion joints at least every 15
feet, better at every 10 feet, but your conditions may be different
than here, along the Gulf coast, for such considerations. I suppose
you know to use an edger, to round over the edges of your slab, so as
not to have sharp edges.
When sweeping the surface, for a somewhat rough finish if desired,
don't sweep any area, that has been in the shade, at the same time you
sweep an area that has been in the sunlight. The areas in the sunlight
will have dried faster than in the shaded area, and the swept finished
surface will be different if you sweep them at the same time. Allow
the shaded areas to dry a bit longer before sweeping. Test the two
different areas for the sweeping to be the same.... Use your common
sense to judge the difference in these two conditions .... I'm sure you
will do a reasonably good job in this department..... This is not
rocket surgery. If your Dad and others know about this, then great.
Allow them to use their knowledge regarding these two drying
conditions, with regard to sweeping these surfaces.
When it comes to the pouring and floating, if you have good help, it
should go well and fairly easy. Most of your hard work will be the
removal of the old and the prep work for the new. If you have any
concern about whether you will have enough help to float the pured
concrete before it dries too much/too fast, then ask the cement company
to add a bit of deterrent to the mix, delaying the drying time of the
mix. But with a little help on hand, you should not need this additive
for delayed drying.
Have a BBQ and invite some friends over...you always want someone else
around to share the blame for things that don't go well. Plan well and
you should do fine.
Hope this helps.
Demo and pouring won't present much in the way of problems. Finishing
it is a little more tricky. You should definitely have someone with a
fair bit of finishing experience on hand. The trick in finishing is
the timing, with weather/temperature, mix and speed of the finisher all
It's unlikely that they put rebar in a driveway slab. Usually it's
either no reinforcing at all or welded wire mesh. A gas cutoff saw is
my preferred demolition tool. You could also cut the WWM with a
sawzall, angle grinder with a diamond blade or bolt cutters.
BTW, a better prepared base and a suitably thick slab will be less
likely to crack than a slab with reinforcing that isn't prepared
Looks like a big job filled with too many "If's", IMHO. Considering how
much it would cost you to do it your self, how much more would it cost to
have someone that does this all the time do the work? It might be worth the
extra cost to end up with something better than "Iffy" results.
Todd, Asphalt over concrete is not really a good application. Every crack in
the concrete will work it's way through the asphalt.
The concrete will move enough with heat changes to make a crack in the
asphalt. I worked with a large road building firm for 30 years until
We had to use a special fabric over the concrete then usually 3 layers of
On some jobs we had a machine to break the concrete into small pieces.
> The existing driveway is about 100 feet long and 10 feet
Todd, If the concrete has been resurfaced then it was probably too thin and
lacked rebar or wire.
With the bulldozer, removal will be easy. Lift one corner and the old
concrete will break easily.
Think through and form the new driveway carefully, paying particular
attention to levels, water flow/drainage, tree roots and crack-line
Proper compaction and a good 6"-8" base (sand/gravel mix), a 16" grid of #3
or #4 rebar and a 4 1/2" - 5" thick (3/4 rock) - 3000lb concrete will insure
the new driveway a very long life.
Finishing a 100' of driveway is not that difficult to finish - unless you
are by yourself and lack a laser screed (
Do yourself a favor and hire a finishing team. 4-5 guys should be able to
do this easily. It will be the best money your spend.
You may be able to use a metal detector to determine if there
is reinforcement in the concrete. I don't know how easy it woudl
be to distinguish between mesh and rebar. I have seen people
break up concrete and dig in bedrock (Sharon conglomerate--
natural concrete) by pounding the bucket down on it. You could
probably break mesh that way, rebar would need to be cut with
a power saw or a jackhammer.
> As the final part of a new addition to our house, we will need to
> new driveway. The existing driveway is about 100 feet long and 10
> wide. It appears that once upon a time, it existed as a concrete
> I'd say it has been resurfaced twice with asphalt. (House is 50+
> old). The new driveway will be about the same length, but gets
moved over 5
> feet or so. The approach to what will be the new gar-shop will be
> different as well.
Way back when, I faced a similar situation, when I wanted to build
about a 10x20 patio behind the house.
Hauled in the sand fill, one wheel barrow at a time, built the forms,
then started to get prices for concrete.
At the last minute, called a guy in the neighborhood who was a cement
contractor and asked if he would give me a price.
The long & the short of it is that the contractor did the job.
IT WAS THE BEST DECISION I EVER MADE.
Laying concrete is an art form as well as hard work.
You are going to need a crew of at least 4-6 people who know what they
If you can get the permits, have the means to remove and dispose of
the existing driveway, then by all means do it, but setting forms and
laying a new driveway is not a job for rookies, IMHO.
Your back will thank you and you will thank yourself in years to come
by walking away from this one.
If you want to save some money, then do the demo work yourself. With a
dozer or back hoe, to do the brute work, then the worst is over (pick
up an edge, and a good wack with a 10 iron/sledge will do the trick). I
would remove all of the debree over about 1 inch. Bigger pieces can
cause cracks when you pour over them. You want a flat smooth sub grade,
usually 3/4 gravel that has been wet down and compacted. A 4 inch thick
slab, with the edges maybe 1 inch thicker will work fine for most
residential drives. 6 to 8 inch thick for comercial. 1/2 inch rebar 24
to 30 inch on center, it is much easier to work with than the mesh.
Crack control joints about every 100 sq. ft (10 by 10 squares) on 4
inch, and every 225 sq ft (15 by 15 squares). These can be hand tooled
or saw cut. The felt expansion joints may not be necessary if the slab
isn't in between 2 structures. I never liked retardents in my concrete,
it would change the texture of the mud to something like peanut better,
then it would be too wet to work for a while, and then gone in
seemingly seconds. In my thirty plus years of concrete finishing, the
last thing I wanted to hear was that the owner had some friend who had
done this before, and wants to help. If you screw up carpentry work, it
is fairly easy to remove and replace, or burn. You are stuck with your
concrete. Hire a crew to pour it for you. You also get charged for
truck time if you go over a time limit. You could do the set up work
yourself, but when the home owner did it themself, I would always check
it out very closely, because most people don't have a clue. I once did
a job for a machinest who set it up himself. The work was good except
that it was dead level. Where is the water going to go? Oh, I didn't
think of that.
Lew Hodgett wrote:
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