[Stonehenge]

Ok - I may have a bit of a feel for why limestone is more prevalent here...One of those is of course it's abundance.

But it appears that in my area we are rich in dolomitic limestone, which according to this agricultural fact sheet: click me, has a lower solubility.

The map below is of the geology of Wisconsin - light blue is dolomitic limestone. I live a couple miles north of the lake in the middle east of WI. Right in the heart of it.

[Paul]

I think we are getting off base here........... We are installing flexible paving system not flat concrete roadway! Yes we want our pavers perfect but frost has a way of pushing things around that we can't stop......well we could but I don't see some of us installing 4+ feet of gravel base.


Now that I've said this can any one here tell me why this type of pavement was developed? My understanding is to ease repairs and add permanency to the pavement. In other words if a problem develops it can be fixed without complete removal or an eye sore of a patch.

[Stonehenge]

The word eyesore is on target, I believe, as it lends itself to the reason we install hardscapes. Aethetics.

Pavers do have the benefits you mention, but just looking at the product offerings by the larger paver mfg says a mouthful. Unilock offers so many colors and textures, from Il Campo to Brussels, Holland to Turfstone. They've just developed a concrete paver that looks and feels like clay. So while functional and structural concerns are valid reasons for a flexible pavement like this, I think that for most, aesthetics is the driving force.

With aesthetics comes the expectation that the pavement move very little or not at all. It's not as pretty if it's being pushed around by nature.

[Lanelle]

In the ICPI course, the origins of flexible paving systems were mentioned. Seems this type of paving (in general) goes back to the Romans. The modern origin of concrete pavers was in Europe right after WWII. Wood was in short supply so firing clay pavers was not possible. Concrete pavers were developed since they didn't require energy to harden or gain strength. This was part of the rebuilding of Europe. Also, in Holland where dikes have to be built to ever higher levels and roads run across the tops of them, the road can be picked up, the dike built up and the road relaid. How am I doing Rex?

[Paul]

We are still missing the point 1" of sand or limestone screenings are not the answer to movement, in the real world 1" or 6" of anything doesn't make the difference in movement. Any moisture can cause things to move, most of us here don't install complete under ground drainage systems. No one here can tell me that their way of installing pavers can prevent water from entering the stone base, or the sub-base. Nor can they hope to prevent natural movement of the soils around them. Again we are not installing on 4+ feet of gravel or building on permafrost.

I go back to my original question, Are we not installing a flexible pavement system?

I've gone back to work that we have done, and have seen things move, concrete curbs that are 2" high or low from when they where installed, foundations that have moved or failed, how many of us have seen roads that we saw installed but failed? All this has happened and we can't stop it!

So it goes to designing a system thats easy to install by relatively unskilled labor, uses locally available material, that easy to repair by the same labor, looks better than other systems over longer periods of time, and is reasonable in price. If any of the above items makes it too expensive for the owner then we are back to square one.

[Lanelle]

I agree that we are installing flexible paving systems. It seems that we need to make a distinction between flexible movement and failure. We need to determine what constitutes failure. There are a number of ways that pavers may fail. I'll start the list. Others, please add to it and then maybe we can prioritize the most serious forms of failure.
1. The individual pavers crack, crumble, crater or spall.
2. The joints open to the point of being a hazard, i.e. heel caps can drop into the joint or the joint deformity can cause tripping.
3. The edges of the installation are no longer straight.

[Stonehenge]

I agree also - this is a flexible pavement. And when I meet with clients and they ask about frost heave, I do tell them that the only way to ensure no heaving is to install a 4' base (I also mention that if anyone else is telling you differently, well....).

Lanelle, that was an interesting bit of history - I'd probably enjoy attending an ICPI class just to hear the historical perspective. Driving through parts of St. Petersburg, FL and Charleston, SC over the last year I got to appreciate some of the felxible clay paver pavements that have been in place for many years (and even a little cobblestone in SC).

It would be interesting to learn of the reasons behind the modular pavements in Europe before the advent of concrete pavers, to see why clay or cobblestone was utilized. Abundant material? Strong enough to handle horse and carriage? Cleaner than soil pavements?

To Lanelle's list I would add heaving and resettling that results in adjacent pavers sitting at heights 1/4" different from eachother, creating a tripping hazard.

I would also add rutting. rutting that results in the inability of surface water to run off the pavement would be a failure to me.

Paul - does NCMA have classes as well?

[Paul]

I'll add uncompacted sub base, or uncompactable sub base as the biggest problems that we see, followed by insufficient base material.

NCMA is the writing body of paver specs and installation process.

I think I'm tiring to get across here is we should follow the latest installation process, some of us are using older methods of installation, that might be slowing down production. While they feel they are giving their customer a better product, I don't believe they are. It all comes down to base material and compaction. If any of the following are not met then pavers installation will fail, improper sub base, improper sub base compaction, improper amount of sub base, improper drainage, insufficient base width to allow proper edge restraint and improper edge restraint. One more thing I'll add on the sub-base compaction don't think that just running a compactor over it will do, test it out take a 3' concrete stake and drive it into the ground, if it takes some doing then your ok but if you find that the first 3" are hard then it drives in easy you are not using enough force to compact with or the sub base might be the wrong type to compact.

I know not many here have access to soil testing services or believe that they don't need them, I find them helpful and proper for the type of work that we do.

[Stonehenge]

I agree to an extent - I think we should use the best, not necessarily the latest, installation methods.

I'm sure soil testing services would be beneficial to anyone - we don't use them on our projects, and I bet that if you were doing primarily sub-1,000 sqft, pedestrian traffic projects, you wouldn't either. I envy that you have such large projects to tackle, but it seems like an added burden for small residential projects, and one that likely would not change how we tackle the project, except in unusual circumstances.

I am interested in finding some reasonably priced density testing equipment, that we might better understand what we must do to achieve the prescribed Proctor densities for base prep. The spike in the ground test you mention is probably a good field test, but I'd also like to have the opportunity to have some real data to work with. Paul, I know you've had testing companies come in and test.

I am still interested in conducting a side-by-side test of pavements, and if any of those who utilize the sand method would be willing, I'd like to get some specs from you that I might use to conduct the test. I'll videotape and still photograph the process, and make the results known here. I'm as interested as the next person in giving the customer what they want - but I also know that specs are made by people. And people are fallible...I am, you are. We all are. So I'd like to get some empirical evidence that one method is better than the next before I change from something that has worked well for us.

And I'm sure that if a method different than my own is shown to be superior, It would appear hypocritical to not change to that methodology.

So let's have it: Let's get some specs - I'll install up to three different bases - the first being my own. 6cm Hollandstone will be the paver used. Tell me the base depth, base materials, compaction (I mentioned I don't have access to testing eqpt yet - so give me a make and model of the prescribed compactor - and it must be appropo for the application, and any field test you have), and we'll get this party started.

The battery is sitting on my shoulder....C'mon. I dare ya.

[Paul]

Here are the specs, http://www.icpi.org/public/articles/TechSpec09.pdf
http://www.icpi.org/public/articles/TechSpec02.pdf

[diginahole]

The currently available testing equipment is likely out of reach for most residential contractors for a few reasons. First being the price, nearly five digits around here. Also the radioactive nature of the equipment would require some additional licensing for transportation and handling. There is a newer technology for which standards are currently being developed that measures soil stiffness rather than density. This to me seems like a more relevant measure than density because it seems to more directly relate to the load bearing capacity of a soil. I have very briefly looked into this equipment (a few phone calls) and the price is still in line with the nukes. I would imagine as this technology becomes more common the price would come down to where the quality oriented contractor could fully utilize this technology. When the pricing comes down to the $3000 range I would likely purchase the equipment. For now at least the first barrier has been removed and the others are slowly being lessened. This year I plan to have 3 or 4 bases tested by subcontractors. I have never had the density test done before and really don't know if I am achieving 95% SPD. I suspect I am, but I would like to know how quickly this is being achieved. Once the density has been achieved it would seem a waste of money to continue to compact. In my quest for greater efficiencies testing would seem to be the only way to know when to stop.

emerging technology

[Stonehenge]

Thanks for the link!

The Tech Specs say that geotextile is optional. If we do it for one, we should do it for all. If we do, I have a good portion of a roll of Mirafi Series N non-woven laying around. Is everyone OK with using this?

Also, the specs don't provide for a method for leveling the stone course. Seeing that it's ICPI specs and I recall Rex mentioning something about +/- 3/8" over 10' (or total possible deviation of 3/4" over 10'), I'll assume that's the spec we'll use. To verify the specs I'll measure in 1' increments using an AGL400 or David White laser level (whichever one we aren't using on a project at the time - both are rated at about the same accuracy - 1/4"/100'). As for methodology, since none is given we'll just use rakes w/ compaction until we're within specs.

ICPI specs also call for paver compaction prior to sweeping joint sand. Once joint sand is swept, pavers are compacted again. Just want to be clear on the methodology...

This is a pedestrian pavement, so the specs call for a 4" min base - I need some clarification of whether additional base depth is needed in this cooler WI climate. Also, they call for compaction in lifts of 4-6". That would mean only a single round of compaction for the crushed stone. And lastly, should I assume the base depth does not include the extra 1" of bedding sand? Just need some clarification.

Also, I mentioned that we do not have a method to test Proctor Density - so I will need some specs as the the compaction eqpt to be used and the number of passes.

If we can get these details squared away, I think we've got a good start.

[Paul]

On soil testing the question for me is do I do it my self of have a company do it? My bases for having a company do it, they will write the report and back it up (their *ss on the line). this leaves me to do the work and not the testing. If you note in spec 2 page 2, there is a chart on compaction equipment, I thinkit will open the eyes of some people here. again it depends on the soil type you have and equipment that you use. Plus it will show some here why I have the equipment I do have. (soils here are mostly clay)

[Paul]

We need to know what type of soils you have?

[diginahole]

It might be more efficient to use a 10' straight edge to verify the base profile. If you can see under it, it needs more work. At least thats the method I use.

Does your laser measure slopes? I had only considered a laser that projects a level beam, if a slope capable model was priced within reach I would certainly prefer that.

I would only use fabric under a driveway in wet or clay situations.

Yes compact before jointing to set pavers in bedding material.

If you don't have 5000# tamper ( I believe this may have been reduced to 4000# recently due to market availability of 5000# units) you will need to use smaller lifts. Several passes are required. I use the same heel test and tamper dance method of testing that you do. I use 6" thick base installed in 2 lifts for pedestrian traffic plus 3/4" bedding sand.