Driveway Base: is 12\" Crushed Stone Overkill?
I am working on putting in a concrete driveway on my new house construction. Since I am going to be spending big $$$ on a concrete drive, probably with some expensive decorative features for the wife like added color and perhaps some edging or texture, I want to make sure it will last a LONG time.
I have clay soil, but the drainage is good as the whole driveway is mostly on a slope and/or slopes away from the house. The driveway will not have any low spots that would collect water.
The specs I am asking my contractors for are:
5 inch minimum thickness
6 inch thick at all edges and where it abuts curb and garage.
4000 PSI, fiber-reinforced, air-entrained concrete.
#4 (1/2") rebar 18" OC, both directions throughout.
12" MN-DOT class 5 (1"-minus) crushed limestone base compacted in 4" lifts.
The contractors I have spoken with have proposed instead 36" OC for the rebar and only 4" or 6" crushed rock or sand base. They claim what I want is over-kill.
I am concerned about using sand base because it may wash out from under the concrete.
I am concerned about skimping on the base due the the clay soil and MN winter frost heave as well as the fact that much of the driveway is built over the back-filled trench from the water hookup (compacted, but not 100-year settled soil).
I like the idea of lots of rebar. The fiber-reinforcing may prevent some of the cosmetic cracks, but once a structural crack appears, there is nothing like a solid chunck of steel to hold it together.
- Rick
I am working on putting in a concrete driveway on my new house construction. Since I am going to be spending big $$$ on a concrete drive, probably with some expensive decorative features for the wife like added color and perhaps some edging or texture, I want to make sure it will last a LONG time.
I have clay soil, but the drainage is good as the whole driveway is mostly on a slope and/or slopes away from the house. The driveway will not have any low spots that would collect water.
The specs I am asking my contractors for are:
5 inch minimum thickness
6 inch thick at all edges and where it abuts curb and garage.
4000 PSI, fiber-reinforced, air-entrained concrete.
#4 (1/2") rebar 18" OC, both directions throughout.
12" MN-DOT class 5 (1"-minus) crushed limestone base compacted in 4" lifts.
The contractors I have spoken with have proposed instead 36" OC for the rebar and only 4" or 6" crushed rock or sand base. They claim what I want is over-kill.
I am concerned about using sand base because it may wash out from under the concrete.
I am concerned about skimping on the base due the the clay soil and MN winter frost heave as well as the fact that much of the driveway is built over the back-filled trench from the water hookup (compacted, but not 100-year settled soil).
I like the idea of lots of rebar. The fiber-reinforcing may prevent some of the cosmetic cracks, but once a structural crack appears, there is nothing like a solid chunck of steel to hold it together.
- Rick