Driveway Strength Questions

[cpeck18]

I've been trying to learn what equipment could safely use my concrete driveway without damaging it. I had our driveway built, and these are the specs we went with:

- 6 inches crushed stone base
- 5 inches of 4,000 PSI concrete reinforced with welded wire
- It's 10 feet wide and ~800 feet long

With those specs, what equipment can safely traverse our driveway without worrying about damaging it? Skid steer? Excavator? Boom truck? Well drilling rig? Concrete truck?

 

[juddspaintballs]

I don't know the answer exactly, but I'd guess if the base is nice and solid and not going to move, that concrete in that thickness should be safe for anything you listed to pass over it a couple of times. I wouldn't make a habit of it, but I think you'd be safe for the occasional large vehicle.

I can't imagine what a concrete driveway that size cost. I just spent $8k getting a 850' driveway cut in to a field and filled with 12" of shale for my house build. I couldn't imagine the cost of pouring the whole distance.

 

[FourthQuarter]

Anxiously waiting to hear an expert chime in. I'm not but guessing what's under the 6" of crushed stone matters quite a bit.

 

[cpeck18]

Anxiously waiting to hear an expert chime in. I'm not but guessing what's under the 6" of crushed stone matters quite a bit.

Good point. Soil isn't exactly my wheelhouse but it seems to be sandier in spots and more clay in spots. This is in NC where there's a lot of heavy red clay. But the county GIS page shows our property as mostly sandy loam - don't know if I buy that. It's sandier in spots and more clay in others.

 

[KansasArt]

Is this for a 1X project that heavy equipment will traverse it? Or regular heavy traffic? I’m assuming they will leave your driveway at some point to work on your project vs just parking there. If so I’d be more concerned about where they leave the concrete surface. Especially if the edge of the concrete sits above grade.

 

[kaymccampbell]

Most folks wait till the construction is done before paving over the gravel base. You might want to consider a temporary construction road.

 

[cpeck18]

Is this for a 1X project that heavy equipment will traverse it? Or regular heavy traffic? I’m assuming they will leave your driveway at some point to work on your project vs just parking there. If so I’d be more concerned about where they leave the concrete surface. Especially if the edge of the concrete sits above grade.

I'm more curious if there are any objective metrics of what's "enough" base and/or concrete thickness to where you don't have to worry about certain equipment. We plan to stay here for many years and I imagine I may have multiple projects over the years. The length of this driveway and the cost to install it (60-80k) just have me wondering what I could ever safely bring back to the homesite/garage as the years roll on. I'm somewhat even wondering if it's even worth it to beef up the driveway specs only for some equipment to damage it versus going cheaper on the specs and having to repair it down the road. Not planning on tons of extra work - but just want to know what a driveway could hold under these specs. I've seen folks in other threads break out math and while I understand reality isn't always as neat as a math equation - at some point some of this has to be subject to some type of physics / math equations - right?

 

[Prospecter]

Clay soil, 4" gravel base 3-4" hot top. I've tri-axel log trucks, 14 yd dump trucks, and cement mixers on it for various projects over 20 years. Never in Spring until the frost is done freezing and thawing. Only problem I ever had was where the logger put down his stabilizer legs.

 

[jack stand]

No one will be able to give you a definite answer, but as Kansas mentioned above entering and leaving the driveway is where it's vulnerable. (driving off the driveway onto the lawn)
Certainly a SS and most excavators shouldn't harm it.
A heavally laden single axle truck might be a concern if loaded beyond the normal 33k lbs. I think in general you don't have anything to worry about until you start talking about a concrete truck. Is your 800' straight? With curves you'll have 25-30' long trucks getting close to the edges.

 

[Rusted Nut]

Most driveways that I have installed for heavy truck traffic are 8” thick 5000# mix with two mats of #5 bar.

 

[bluedog225]

Surprised no actual rebar. Too bad.

 

[ConCretin]

Anything that can drive over the road to get to your driveway won't hurt your driveway. Don't sweat the fact that you don't have rebar. It wouldn't increase your concrete's ability to resist cracking under load - that is a factor of the concrete's thickness and the load bearing capacity of what's under your slab. If the material under the stone is reasonably stable, you'll never crack your concrete under normal loads.

 

[cpeck18]

Surprised no actual rebar. Too bad.

Any idea what rebar may cost over 800 feet? Just curious

 

[cpeck18]

Most driveways that I have installed for heavy truck traffic are 8” thick 5000# mix with two mats of #5 bar.

That would be nice, but at 800 feet a driveway with those specs would exceed $100k

 

[bluedog225]

Yeah. Would have been pricey no doubt.

 

[bluedog225]

Can you bring in the heavy stuff over the dirt when dry?

 

[ConCretin]

Any idea what rebar may cost over 800 feet? Just curious

If you placed #4 bars at 12" centers for an 800 x 15 pad, you'd need about 8 tons. Two mats of #5's at the same spacing would be more like 25 tons. We're paying about $1,500 a ton right now for cut and bent bars including delivery. Supports would probably run a grand or two for one mat and twice that for two depending on what you use. If you figured 12 man-hours a ton that would range from 100 to 300 man-hours. Your results would likely vary but this should give you an idea.

 

[cpeck18]

If you placed #4 bars at 12" centers for an 800 x 15 pad, you'd need about 8 tons. Two mats of #5's at the same spacing would be more like 25 tons. We're paying about $1,500 a ton right now for cut and bent bars including delivery. Supports would probably run a grand or two for one mat and twice that for two depending on what you use. If you figured 12 man-hours a ton that would range from 100 to 300 man-hours. Your results would likely vary but this should give you an idea.

Thank you for both of your very helpful replies. I appreciate you sharing all of your concrete knowledge!

 

[AC-WC]

Skid steer-yes
Excavator-probably, if it can fit on 'car' size trailer. Semi trailer size I would say no.
Boom truck-probably- I have 6" with mesh and the co-op pulls in all the time. Same for Propane/fuel delivery truck
Well drilling rig-yes, I had no problem when they redid my well and pulled back and forth over it.
Concrete truck-NO! Unless you're 8" thick I wouldn't and that would be uber expensive for that distance.
As others said gravel until all the rest is done then do the driveway. All that traffic helps pack it down for free

 

[Firebrick43]

Skid steer-yes
Excavator-probably, if it can fit on 'car' size trailer. Semi trailer size I would say no.
Boom truck-probably- I have 6" with mesh and the co-op pulls in all the time. Same for Propane/fuel delivery truck
Well drilling rig-yes, I had no problem when they redid my well and pulled back and forth over it.
Concrete truck-NO! Unless you're 8" thick I wouldn't and that would be uber expensive for that distance.
As others said gravel until all the rest is done then do the driveway. All that traffic helps pack it down for free

An excavator, even a large one isn’t going to put more than 10psi on the ground if the operator isn’t stupid.

Your drill rig is going to put 110 psi and a concrete probably 120 psi.

 

[cpeck18]

An excavator, even a large one isn’t going to put more than 10psi on the ground if the operator isn’t stupid.

Sometimes a big IF

 

[Firebrick43]

Sometimes a big IF

Yes it is.

Many operators do jump turns which in some instances is necessary but it’s hard on the tracks and it obviously raises ground pressure significantly and therefore detrimental in some places.

 

[KenC]

Personal experience. Dad built a 300x10ft drive about 1970. 4" (probably really 3 5/8, as that is what 2x4s were then) 3500lb mix. It served an auto salvage so lots of car & pickup traffic plus our wrecker and haul truck regularly. Not a single failure until 1990 when he retired and had all the cars baled. The last load that was hauled was almost 100K! Lots of weight. Still didn't damage the main path but broke the edge off for a short span when the driver failed to center the load on the drive. To this day that is the only crack damage. There is a lot of spalling from freeze/thaw cycles though.

 

[cpeck18]

Personal experience. Dad built a 300x10ft drive about 1970. 4" (probably really 3 5/8, as that is what 2x4s were then) 3500lb mix. It served an auto salvage so lots of car & pickup traffic plus our wrecker and haul truck regularly. Not a single failure until 1990 when he retired and had all the cars baled. The last load that was hauled was almost 100K! Lots of weight. Still didn't damage the main path but broke the edge off for a short span when the driver failed to center the load on the drive. To this day that is the only crack damage. There is a lot of spalling from freeze/thaw cycles though.

That's a great example. That driveway has had a good life!

 

[pcmeiners]

60-80k, for that amount having the soil tested, and spec'd for compaction by an engineer would be cheap insurance. Concrete strength is important, but the correct amount of compaction is just as important, if not more.
In your case picking the correct time of the year is very important, spring or fall for cool weather, I would not consider a summer or late fall pour.

 

[reader2580]

No one will be able to give you a definite answer, but as Kansas mentioned above entering and leaving the driveway is where it's vulnerable. (driving off the driveway onto the lawn)

I have (had) an asphalt driveway. A dump truck misjudged his turn and drove on the edge of my asphalt driveway right off the street and destroyed the edge. The end result is the concrete contractor replaced the first thirty feet of my driveway at 25% off his normal price. The remaining dump trucks and concrete trucks drove across my lawn instead. There is a ditch and I am surprised the trucks made it through. The lawn damage was minimal.

You're right to state the entering and exiting a driveway is very important.