concrete question

[Bob Weisner]

How many yards of concrete would I need to cover a space 18 feet wide by 90 feet long . concrete being 2 1/2 to 3 inches thick.

Thanks,

[Jeff Sudmeier]

According to my calculations you would need 15 yards of concrete. Concrete is much like wood, it never goes as far as you would think it would, so 15 would be a minimum.

[Don Baer]

if 3 " then 15 yards

[Bob Weisner]

If there is already an old concrete driveway present, can the new concrete be poured on top of it?

Thanks,

[Jeff Sudmeier]

Bob, just found the formula that Doug Shepard posted in another post:

(L*W*D)/324=Yards
L&W in feet, D in inches

Can you pour old concrete over new? Yes, I have done it... If you do, you want to put a layer of 3mil or thicker plastic over the old slab.

However, why do you want to pour over the old slab? If it is because it is all cracked up, it will not make a very good base. The reason that we did it because we got some concrete for free, because it was 10 bag mix (Sets VERY fast) that was setting up in the truck. Turned out we couldn't get it smooth so we poured over it. In our case, we had a great base! If the current slab is cracked, it won't make a very good base, because it has already moved and will move when the new slab is poured.

[Ian Barley]

Wotcha doing with it Bob? - have you considered the need for reinforcing mesh and/or expansion joints?

[Bob Weisner]

The concrete "driveway" , is actually the old road that is in front of my property. I talked to the Town about getting them to resume the maintanence of the road, but they are not sure if they actually own the road. They think the County may be the true owner of it. If it turns out that they will give ownship of the road(They have not done anything with it in 59 or 60 years, then I would like to patch it up. Since it is solid concrete, I don't think blacktop would work. The road does not have potholes, persay, it is just really rutted and chipped.

Thanks,

[Jeff Sudmeier]

Bob, in this case, I would think that the concrete would stay stable. Basically you want a firm base that is not going to move much for concrete. If the street was cracked and heaved, you wouldn't want to lay over it. If it is pretty much stable, you should be fine.

Don't forget the plastic. This will keep the two layers of concrete from joining and will allow them to both move independently.