Grading Grading with a BX

[shrekbelly]

folks,
i hope i'm in the right forum. here goes, i need to have at least one truckload(possibly two) of dirt dropped on my driveway, where i get to work/play by moving it to an area off the back of our house via the kubota's fel. we're going to be putting in a patio sometime next year.
people have told me that the soil should settle for a year before buiding the patio?!?
i have the hd 2763a front blade already, what other implements you i be looking for? i have a need for a landscape rake for other area projects on the property. thanks for your time and attention robert a. aka shrekbelly

 

[ampsucker]

howdy,

not sure what you are calling dirt. around here, topsoil would not be used for fill. but, a lot of folks consider "dirt" to be pretty much unsized rock.

if pouring a pad, you would actually want gravel as a base. it's easier to compact, level and you don't have the settling and erosion issues. (ie areas under your pad hollowing out in heavy rains)

i have had the best luck leveling with a rear blade. haven't tried a front blade, but i know with the FEL, there isn't much steerage when the bucket is down.

level it when it's loose, it's much harder after compaction. you might also want a roller or something to help compact your base once it's mostly level. then you can fine tune with a drag or shovel to get ready for pouring cement although it doesn't have to be perfect...

amp

 

[Jimbrown]

Truck load? 5 yds, 20 yds 40 yds? I have never used a front blade but a rear blade works fine as would a box blade. If I was gonna put concrete on top of it i would use AB2 not dirt. AB2 = gravel with fines and some clay/cliche mixed in it. Once spread and wet down it gets almost as hard as concrete.

 

[dodge man]

I work for a civil engineering company and we deal with dirt compaction on a regular basis and test for it. He is correct, gravel would be better. Top soil would be bad, to many organics, although clay or sandy soil would be good. Place the soil in thin lifts, roughly 4-6 inches thick. Then roll it. Ideally a sheeps foot roller would be used, but you probably won't find one that small, so a smooth wheel would be O.K. Moisture is also critical. You may need to add water or let it dry first. We actually test the dirt and determine the optimum moisture, but you won't likely have that option. You can kind of tell by picking up a hand full and experiment with it to see how well it packs by squezzing it with your hand. Don't figure rolling with your tractor wheels will be enough. Under ideal conditions this can work, but tractors are designed NOT to sink in and compact the soil. If you let sit a year, that will help alot, even more so if it gets alot of rain on it. If you compact it correctly to start with, you shouldn't have to wait at all. This same procedure holds true with gravel, but it obtains its density a little easier.

Hope this helps.

 

[shrekbelly]

ampsucker,
my thumbnail explaination was inadequate. good ol' fashsion dirt for base, then stone/gravel (using some kind of paver for the patio) and the topsoil for patio collars to blend into turf/lawn. thanks for your response. robert a.

 

[KeithInSpace]

From a Civil Engineer who JUST installed a 350 sf brick patio:

To serve as an adquate base for a patio, you must to rent a 'jumping jack' amplitude-based compactor, compact the area of interest before you put anything on it (as it sits today). Then you can bring your additional soil in with 6" lifts and compact each layer as you bring it up. Only with amplitude-based compaction can you 'tear' the soil and get effective hardening of the subgrade. Keep going until you can't drive a stake or landscaping nail into the ground. You'll know.

As others have said, organics in the topsoil doesn't work...it never 'tightens'. Free junky junk will always turn to soup no matter what you do to it, unless you get another truckload of LIME to go along with your 2 truckloads of junk. And you don't want that. It is expensive and very, very messy.

Simply placing the soil in one spot and litting it "settle" will not effectively compress the entire area or, most importantly, the subgrade. And it won't happen consistently, so you'll end up with sinkholes. And using a compactor after you install an 18" deep lift won't allow you to compact the deeper section of soil, leading to the same problems. The folks telling you this probably use the term "surcharging" the base, but you need a HUGE MOUNTAIN of soil to effectively surcharge and, most importantly, you need to install a french drainage system since the only way to 'tighten' the in-situ material is to push all the water out of it. You're not doing either (certainly not the first and probably not the second), so making a big pile is pointless.

Using the front tires of the tractor with a loaded bucket is OK for really (really, really, really) light duty stuff or things you don't really care about, but it is insufficient for anything that matters.

Before you install the stone, be sure to lay a WOVEN geotextile fabric between the stone and soil. In case you have any weak spots in the soil, the geotextile fabric will add another structural element to "hide" minor imperfections. Don't use NON-WOVEN fabric as it does not have a structural component/benefit and simply acts as a media seperator. The fabric is cheap. Hold it in place with sod staples.

When you add you gravel (proper base for any patio, be it concrete or brick...4" to 6" in depth, depending), be sure to properly compact it in lifts as well, but use a FREQUENCY-based compactor, also called a 'vibration plate' compactor. Graded stone (crusher run with fines...never use evenly graded stone) does not respond to the jumping jack...graded stone relies on the vibration waves to fill in the gaps in the stone with fines to create a hard base. Work from the perimeter inward to force the stone "into" itself, then make multiple passes in different directions.

And when you add sand, never use "concrete dust". It is junk. It holds too much moisture and is inappropriate for a structural application no matter what ANYONE tells you. Trust me. I know. Use WASHED SAND. It is more expensive, but it is the right material to use.

Happy to discuss further if you have any specific questions. Feel free to PM me.

 

[dodge man]

Keith has the best idea, one that I didn't think of, but the jumping jack would be the best, it will really pack in the dirt. They also make other plate type compactors that would be O.K. I have also seen really small sheeps foot rollers that can be rented. Kind of like the small ones used on ashpahlt, self propelled and all. Alot of it depends on how big of an area you are talking about. If its not really big, the jumping jack would work fine. I have seen thousands of cubic yards of dirt placed and compacted, and it can be a battle at times, but for what you are planning its not super critical, its not like its a building. The large fills are always placed with a vibratory sheeps foot roller. If you don't do a reasonable job on the compaction, it will settle big time.

 

[KeithInSpace]

Vibration plate doesn't do squat to dirt subgrade. I promise. Waste of time.

Sheepsfoot is OK as long as it vibrates. They make those little remote-controlled articulating trench compactors that would be nice if you're doing a larger area...just sit in the lawn chair and drive it back and forth. Obviously, if your doing a very large area (large. Parking lot or 10,000+ sf paver driveway), you need to rent an actual vibrating sheepsfoot roller...the big one, I mean.

Anything under 600 sf or so, definitely a jumping jack. If it start pushing over that, you may enjoy the larger self-driving unit. My 350 sf was very easy with the jumping jack.

 

[dodge man]

I guess in the construction buisness, I've never seen jumping jacks used for flat areas, only tight areas such as around foundations and in small trenchs. I think you are correct, it will by far be the cheapest and do a really good job. They just always look like they beat the heck out of you.

 

[KeithInSpace]

...I've never seen jumping jacks used for flat areas, only tight areas such as around foundations and in small trenchs.

Because nobody bothers. The patio guys will sell you 6 inches of concrete dust, MAYBE "upgrade" you to a layer of geo fabric, and tell you it's great...I'll pit my patio against ANY professionally installed brick paver patio set in concrete dust on un-compacted ground (as most of them are). May look OK now, but I'll guarantee what it'll look like in 8 years.

Not exactly a ride in a Cadillac, but the jumping jack really wasn't that bad. It just bounces along. Almost drives itself. I grew up on a front-tine roto-tiller my Dad had. Tines were always dull. Now THAT was an unpleasent drive!