Load test for the test pavers.

[Stonehenge]

What would be an appropriate load test for these pavers?

Run a narrow compactor over the same path multiple times?

Pull out the big guns and just drive our 7,500# skidsteer over it?

Wet it down before we test, to lube everything up?

[Paul]

Asking me, run a skid steer with a full pallet over it.

[Stonehenge]

The 'no screwing around' option, eh? That's what I was thinking, too. The purpose is to make this fail, to see which is toughest.

[diginahole]

I'm with Paul. Mash em up.

[Paul]

A couple of things items should be watched, #1 edge restraint movement, a failure here would lead to premature failure of the test site. #2 edge failure, due to lack of enough base extention.

[diginahole]

Maybe hold off on the water until after the first crack at it too. It may show that screenings hold onto more water than the other bases. I'd bet you see water coming up through the joints on that area first.

[Stonehenge]

The base was extended a minimum of 6" beyond the paver area
(we usually do 8-9"). The area isn't wide enough for the whole skid steer to fit, so I was thinking 1 row of wheels right down the middle. That might also mitigate edge restraint failures.

Also, in fairness to all base preps, the very middle of each prep should be what is measured, and not the outside edges. The all screenings base is in the middle, therefore making it less likely to have any edge failures.

[Stonehenge]

Here's a few low-res pics of the process:

Prior to excavation...

[Stonehenge]

Compacting excavated area...

[Stonehenge]

Geotextile....

[Stonehenge]

Partially prepped...

[Stonehenge]

Screeding sand...

[Stonehenge]

Laying brick....

[PSUscaper]

Hello,

Simple load test.....

loaded tandems.........driving over it 10 times a day for 2 weeks......

that's a test!

Honestly, I think your testing is going to prove very little.

There are just TOOOOOO many factors involved to test here.

First of all, the area is just too small......

Have you ever seen the Army Corps. of engineers test sites.

They took a dirt road intersection at a military base (a tank base) and installed pavers at the intersection.

Then..........they had hundreds and hundreds of tracked vehicles (M1 abrams, bradleys, etc) drive over it every day.... Let me tell you........these things were MOVING!!! They had tanks literally doing 45mph hit the intersection and bang a 90 degree turn at full speed.

The pavers in the middle were perfect....however.....

Edges were always a problem.

With such a small area being tested, I don't think you are really going to get any real results.

What are you testing here???? How well a residential walkway will hold up to having a skidsteer drive over it???? Is this something we really need to know the answer too.

I can tell you the results now......if you drive the machine down the sides, the edges will fail.....

If you constantly drive it up and down the middle, it will sink......

Its a walkway....not a drive.

I think to get a load test you need a much larger area to test.
6 ft wide isn't enough. The strength of the pavers comes as a whole. A larger area disperse the weight across a large foot print. With such a small area, you are dipersing a large amount of weight on a small area. Think of this paver area as the tracks on a rubbler tracked skidsteer.................What disperses weight better.....narrow tracks......or wide tracks????? I think we all know the answer here. Pavements are kind of like the tracks on a machine............they take weight from one small spot and disperse it across a larger area..........your area isn't too big.



Also, you have chosen a very weak pattern. Running bond is perhaps the weakest patterns out there. Also, the way the running bond is laid makes a difference. I've always been taught to run a running bond perpendicular to the direction of travel.

The running bond you are testing is going parallel to the direction of travel.........the weight of the machine is going to be all on a 3 brick wide strip (the width of the tire say).........those three rows of brick will press in where the long joint lines are. The weak point of a running bond. If you drive the machine across the running bond the other direction, then the pavers are kind of jointed together better (kind of like taking both your hands together and curling you finges around the backside of each hand) and the pavers will hold up better.

Also, you have kind of foiled your test site already by having it against a building. You have a 'immovable' edge restraint on one side and are going to have a much weaker edge restraint system on the other. You need to keep all factors 'the same' to get real results.


I just don't understand what you are trying to prove here that hasn't been proved hundreds and hundreds of times already.

If you want a real world test site I can show you one......I had to do a 10 foot deep by 16 foot wide paver drivewat apron at a house last year that was no where near being finished. The drive was still 3/4" gravel all the way up, and it was on about a 15 degree slope.

To complicate things, the apron was completed in the rain(add that factor into your equations). Also, there was a 4" gas main running under the drive in a 2 foot wide trench backfilled with dead sand about 12" under top of paver running under it, a water valve shut off under neath it (I hope they don't have to find that one ever:) ) and electrical conduit for a gate control box.
In lieu of all this, the ground was like and old quarry........little dirt and a lot of 6" size shot rock that must of been there forever.

After we did the apron (we had to get the apron done so they could get a temporary CO in case your wondering) the fun really started. We had close to 200 yards of soil brought in, at least 300 yards of fill brought out, lowboy trucks with 20000 lb excavators, had bulldozers drive across it with plywood on top of it, and had about a gazillion sub-contractors vans along with the homeowners many cars drive over it for a period of about 6 months.

To that add the gravel drive and the hill to it...........after about a week the entire thing was coverered with 3/4 gravel.......How does the load get disperesed on a brick when a 80000lb tandem backs over it while crushing and pushing 3/4" stone into the top of it??????????

I'll tell you....

Quite well. I'm not saying this thing is anywhere near perfect....but...................all things considered, I can't believe it looks as well as it does. There are slight tire ruts up and down the apron where the most traffic was, but really not that bad. Wher the pavers stopped and the 3/4 stone drive started, the brick actually stayed in place amazingly well...........I just used a small amount of concrete for edging only, and was shocked that it lasted.

I just wanted to mention this whole thing because as I said......there are just TOOO many factors involve here are you are only testing a tiny, tiny fraction of them with this whole test site.

If anything, you'll have a nice level place to store snow plows in the summer time:)
steve

[Stonehenge]

Steve, thanks for the detailed response, as always. :)

However, if you check out the ICPI thread, we talked a bit about what we were testing, and the pattern of pavers we'd use for the test.

The pattern was chosen because it was the weakest. We want to test the base, not the pavers. Laying the weakest pattern will give us a better opportunity to test the base.

Small area? True. However, as this is a test pavement put together by someone with a limited budget (considerably smaller than the US Army), a smaller test area was needed.

I anticipate the edge will be destroyed. I'm not really interested in the edges. My greatest interest is in the middle of each of the test base areas, and which ones fail first/last longest. Whichever base is best here should also be the most durable base for other patterns, other pavers.

As for being proved hundreds and hundred of times already - I'll say now what I said before - engineers are smart folks, who I studied side-by-side with when in college. Many of them, including some of the civil engineering faculty where I attended college, were less educated in real-world applications. There are so many things that work on paper but not in application. Also, I've never seen a test like this in person. I would bet that most people out there haven't either (most, not all ;) ). :const:

So I want to see for myself, do for myself, and provide for the rest of the folks who visit here the chance to see a test like this for their own eyes (more or less), and see that everything was prepped in an equally workman-like manner, and that there was no bias for one method or another.

The intent is for it to sink - if none of them sink, then we have found an unexpected answer, but an answer nonetheless. I want to see for my own eyes which base prep method will allow us to install the best work we can for our clients. Whichever sinks the most is the loser, the one that sinks the least is the winner.

If nothing else, it may prove that the method Rex and Paul and Digin have been hammering on for so long is the best - then everyone gets the added benefit of me having to shut my mouth when it comes to base prep. :zipped:

[Paul]

But will you change?????????????????

[Stonehenge]

I said I would in that thread, and I'll say it again here. Yes I will.

I'll put it this way - it would be pretty hypocritical of me not to switch, if the best method is not the one we use today.

I can imagine talking to my clients: "We did extensive testing of base preparations and are proud to say that we know which one is the best. Unofrtunately, we won't be installing your pavers using that method." :huh:

Of course, our way has to be proven inferior first... ;)

[BRL]

LOL It turns out Henge is testing just one of those fractions of factors. Regardless that was a great post Steve. Thanks.

"If nothing else, it may prove that the method Rex and Paul and Digin have been hammering on for so long is the best"

Can you post the fundamental differences in thought in this thread please? So we can consider that while following the testing results. Thanks. And thanks for doing the test & sharing. Pretty cool thing to observe from afar.

[Lanelle]

I'm concerned about the photo of the sand being screeded (#5). Once the sand is placed into the area, I don't allow any feet or significant weight on the sand bed. Ideally, the sand is uniformly fluffy when the board is pulled over it. Footprints create uneven areas of compaction in the bedding.

[Stonehenge]

Lanelle was trying to be kind to me and sent this to me via PM, but I invited her to post it here as well. I'm not sure how one would go about creating uniform 'fluffiness' in a sand that is wet in some places, dry in others - flowing in some spots, clumpy in others. After Lanelle's PM I tried to find any info about screeding the sand and could not find anything indicating that prior to screeding the sand it should not have any pressure applied to it.

Also, I was under the impression that this same thing happened when walking on the leading edge of pavers, but that compaction evened that out later.

So I'm interested in the opinions of others here in this matter.

BRL, I'll let someone else talk about the difference in theories with the different base preps...I do enough talking around here. :shutup:

[PSUscaper]

I guess you would have to have a portable screening device on the job to sift the sand out and make it 'fluffy'.

Hears an idea........get a bunch of those flours sifters (you know, metal type, have a 'trigger handle' that makes a little propeller spin around inside) and and have your guys 'sift' out sand.

ok....probably not.(though I may not put it past mr. henge.....)

I can't see getting uniformity in sand that precise without spending a rediculous amount of time.

Also, the fact is, after you place pavers and before you compact them, you walk all over them.

I've always gotten confused by those mechanical buggies. They show them dropping sheet after sheet of pavers in, and while they are doing it, they are driving all over the uncompacted pavers. Isn't this a problem????

This is like a 1 ton plus vehicle driving all over the uncompacted pavers. Meanwhile, most people are only walking on them before final compaction.

If the vehicle is approved to drive over uncompacted pavers, and we are allowed to walk over uncompacted pavers (for how else would we be able to sweep in joint sand), then using deductive reasoning, I say footprints on unscreeded bedding sand (or for that matter, footprints on screeded bedding sand that is then hand trowel smooth) truly amounts to NOTHING!!!!!!!!

thank you.

steve

[Stonehenge]

BRL, I think what these 2 base prep methods comes down to is this:

2 of the 4 preps are both using crushed limestone. One is 3/4"-, one is more like 3/8"-. They are both very angular, making them both good options as a base, because the stones will lock together due to their angularity.

Paul, Digin and Rex believe that it is better to have larger, angular stone under much smaller, angular sand, as a base prep. I believe the smaller, angular stone will perform better for this type of pavement. I believe the test will come down to: does the sand really do the job it's billed as doing, and can the limestone screenings do the job I say it can? The answers to those two questions will determine which base is proven best, IMHO.

[Rex Mann]

When your working with sand as the bedding course you have to use more caution. Caution not to walk or wheelbarrel on the already screeded sand. Caution not to screed wet sand. Damp is okay, but not wet. My definition of wet sand is, trying to make a ball of it and it runs out your hand and between your fingers.

As for fluffy sand: We do not have a standard for incorporating any air into the sand prior to screeding. I do not believe walking, kneeling or standing on the sand prior to screeding compromises the compaction factor of the sand in that specific area. We do use the term "fluff the sand". Our definition is to incorporate air into the sand after a screeded area has had some rain or other type of moisture added to it. The screeded sand will "flatten out" or "lay down". We will take a hard rake and "fluff" it up.

Walking on the pavers is a necessary evil. However, everyone of us knows how to walk on them to minimize the settling. Also, we never walk on the laying face or soldier/sailor course. At least we try not to.

Laying machines are generally used for 80mm pavers. With 80mm pavers the vertical and rotational interlock are much more significant then 60mm pavers. Translation....they resist "rolling" far greater than standard 60mm pavers due to their combined thickness, weight and sometimes footprint.

Peace,

Rex

[Stonehenge]

Rex sent me an email with a link to a fantastic site. I wanted to share it with everyone else - http://www.classichardscapes.com/index.htm

As far as I can tell this is a design/install firm, but they have a site that is really full of solid information, and has just a gorgeous layout and graphics.

They provide some good info about interlock, which is what Rex was sharing with me. stop over there and have a look when you get a chance.

Jeff