ICPI or not [Archive] - How To Landscaping

Stonehenge

03-26-2003, 08:15 AM

I haven't gone through the training but have read some of their materials. They advocate the use of a sand bedding course over the stone base course, and I am as yet unconvinced that this does anything to improve your base prep, from any perspective (drainage, durability, etc). But I'm always willing to listen...

We have found a few applications where sand is necessary, but for the most part we do not use it.

Digin - the screed guides you mention - we use pipe set to the appropriate pitch - is this what you use string for?

Lanelle - I do like the idea of a standard set of procedures for people to follow, so that the job gets done the same way every time.

And speaking of ICPI - how many of you are members, not just certified? I was thinking about joining.

This discussion has been included in the site beginner's brick paving (http://www.groundtradesxchange.com/pavers/brick-pavers.htm) page.

Rex Mann

03-26-2003, 03:29 PM

Jeff,

ICPI is not about teaching the steps tp laying pavers. They are
about educating contractors as to why problems occur and how to avoid them. They dispell alot of "old wives tales" about installing pavers.

The reason we use a sand bedding course, which by the way is concrete sand as opposed to mason sand, is the sand allows the moisture to drain. The sand has 0% fines passing the #200 sieve. The ASTM for the sand is 133. The more fines you have the more moisture retention will occur. The more mositure equals expansion. Also, when the pavers are conpacted over the sand it will come up between the joints. Certain patterns and pavers can have very small joint lines. If you are using linestone screenings, which are well above 12% fines passing the #200 seive, they are not small enough to come up through the joints.

Our company is a member. I am certified and also teach the class through the ICPI to become certified.

The class is very interesting and worth the investment of time and money.

Peace,

Stonehenge

03-26-2003, 07:50 PM

Rex, I think I was baited!! :o That's ok, I'll almost always take this bait....

When using sand, where does that water drain to when it drains? To the stone beneath it. And with a coarse stone, no matter how sloped the pavement, it will be a pretty direct path from the paver to the compacted stone. So better drainage to me is the 'wives tale'. The crushed stone beneath, though thoroughly compacted, is not so dense that there is an absorption rate like a concrete or asphalt - the stone beneath the sand readily absorbs the water. The sand does not create some sort of hollow conduit through which the water passes. And I agree, more fines (meaning more total surface area on which water can sit) means more moisture, whcih can lead to expansion in freeze-thaw. But the stone beneath also has fines (though admittedly not as high a content). So it's a matter of where the expansion will happen, not if. Sand just makes the expansion happen an inch deeper than it would otherwise.

I agree, that the larger stone size of screenings does impede the stone from rising into the paver joints - but as you mentioned, if 0% passes the #200 sieve for the concrete sand and 12% passes for the screenings, then there are screenings that are smaller than the sand, which can and do rise into the joint upon compaction.

I don't know much about what the course offers, other than what I hear from people involved in it...Certification seems to imply teaching a methodology and testing that learning - so I hope there's some teaching going on re: certification.

I would very much like to conduct a test of these two methodologies. Maybe it's something several members can independently verify. If we were to conduct a side-by-side test of these two methods, what would the specs be for your method using sand? Please be specific with pitch (and method to set it), compaction (in a practical sense; I can't afford to have densities tested, but I'll use specific compaction eqpt a specific # of iterations to meet your usual specs), etc, then let's also create a test for the two pavements, and a method for measuring their durabilities. I'll put some specs to paper for my install.

Who knows, this may be fun! :p

Rex Mann

03-27-2003, 12:10 AM

Jeff,

Those 12% passing the #200 sieve, which is on the low side, are actually part of the pieces of the screenings. They are like the chocolate on a chocolate covered pretzel. They both "flake" off. Therefore, there is not enough of these fines to help create a lockup effect. The only significant lockup you can achieve is through your joint sand. And, using screenings will deter progressive lockup. The screenings themselves are made up of silt and clay. We all know silt and clay are the worst types of soil to build on. We have all experienced how slippery wet clay can be. Transfer that idea to the screenings. The screenings continue to move and shift when moisture is introduced. And, because they are made up of silt and clay they always hold that moisture. The base stone is best suited at 8% passing the #200, but the ICPI spec ranges from 5 to 12 %. Within these ranges the best compaction can occur. We need moisture for compaction. That is why we need fines-to hold the moisture for this function. With the proper gradation of base material and pitch of the soil we can minimize the moisture content that will be held.

We install pavers just like you do except we use sand as the bedding coarse rather than other materials. We do not precompact the sand. Our base is 95% proctor density as is our soil. Then we screed sand 1" to 1 1/2" then lay pavers. Our tolerance for the base is + or - 3/8" over 10 feet. We want to have a consistent thickness of sand. When I say our sand is 1" to 1 1/2" thick do not become confused. This simply means that the sand can be between this range, but not on the same job. Meaning 1" thick on one job is okay. Then the next week using 1 1/2" on that entire job. I like to use one inch of sand-saves time and money.

I would suggest taking the class to anyone who is serious about installing pavers. More architects, city planners and engineers are specifying ONLY ICPI CERTIFIED CONTRACTORS MAY BID. And, we get allot of work because we have taken the classes.

Peace,

diginahole

03-27-2003, 12:15 AM

Jeff, rather than laying pipes I prefer to string several crossing lines to ensure a very flat surface. I have been using this method for alot of years and it is pure stubbornness that keeps me using it. It probably takes more time and is certainly more difficult. Although, I can spread as fast as 2 guys can barrow material into a back yard. It would certainly be easier to teach screeding than my rake to the string method,followed by smoothing out the sand with a 7' straight edge. This may be the year I pick up some pipes.

I too am firmly on the side of a sand bedding course and was even before the ICPI training. This may be more of a local issue as I have not had the opportunity to see limestone aggregates from other parts of the world but would imagine the following detrimental characteristics to be true of all limestone aggregates. Limestone makes beautiful decorative landscape rocks for one simple reason, limestone dissolves in water. Because of the fines content of screenings it holds water that causes it to dissolve. I have dug up many driveways that are only a few years old where 3/4 crush limestone now resembles and feels very much like saturated clay. Saturated clay as we all know is just about the worst base imaginable. You will not find limestone aggregates on any of my projects ever again.

Stonehenge

03-27-2003, 08:20 AM

Digin,

I would think you'd need the hands of a surgeon to make pulling a 7' straight edge come out flat and uniform. I recall the first paver project I ever did, which was also the first paver project that company had ever done. We had a 10' board that we pulled across compacted slag sand. Me and the company owner, each with one cheek almost touching the board to eyeball straightness, sawing the board back and forth across the surface to be paved.

I can only imagine what that project looks like now. :frank:

Thankfully, about 2 weeks after that project the company hired a top foreman from what was at the time the biggest paver installer in the midwest, and my foundation of paver knowledge came from him. But I'm getting off track.....

Every stone wears down in time - true, some go faster than others. I'm not sure what the limestone looks like near you, but around here it is the base of every pavement made - highways, streets, parking lots, sidewalks and patios. The 3/4- is a lot of 3/4, not much '-'. Makes for a very durable base. If the ones you've seen are coming up mush, I'm betting there was a high fines/dust content to begin with. Digin, what type of stone do you use in your base?

As for the screenings I use for pavers, it may be different than most screenings. Some of the bulk sellers here offer screenings that are very uniform and typically just larger than a coarse sand. I've used that and didn't like it for the occasional 'mushy' reasons you describe. The supplier I use most often has screenings that are quite a bit more robust, larger pieces, fewer fines.

Some of the other things I don't like about using sand:

You can't predict the moisture content - bulk sand will have pockets of dry sand, pockets of wet sand. When spread the wet is clingy and the result is less sand in that area, while the sand flows where it's dry. Final result is pavers sitting lower where there was wet sand. Paver compaction will certainly aid in evening out that inconsistency, but it's a (albeit slight) inconsistency nonetheless.
It's difficult to lay pavers on sand - not the placing of the pavers, but walking near the edge of the just-layed pavers almost always causes some pavers to be pushed into the sand, altering bond lines. Again compaction mitigates, but can't always completely repair.
Most install manuals I've seen that include a sand bedding course always mention using the sand to 'level out the uneven spots.' Gives the impression the function of the sand is more of that of a spackle than anything else, the statements here notwithstanding. Organizations that are proponents of sand should eliminate that wording to remove that impression.

I would also imagine that with the advent of polymeric and organic sand binders (dropping the absorption rate of the paver surface), drainage through materials beneath the paved surface is much less of an issue.

There was something else I wanted to add, but I can't remember it....darn it. I'll add it later if I think of it.

Does anyone know if the National Concrete and Masonry Association (NCMA) has classes as well? I've received a few of their newsletters and they seem pretty informative.

Debate is good - helps ensure we're all doing the best job we can. I hope nobody's toes feel stepped on (Digin, Rex) - I'm enjoying this process. :)

Rex Mann

03-27-2003, 02:23 PM

Jeff,

Good point on the sand be thought of as the leveling agent. That is why we promote the + or - 3/8 inch over 10 feet. We used to call the sand the leveling coarse. Not anymore.

Peace,

diginahole

03-27-2003, 03:42 PM

The method I use to pull a 7' edge is more akin to icing a cake than traditional screeding. As I get older it becomes more and more difficult. Imagine if you will a chubby guy bent over at the waist dragging a level in 1/4 circle patterns at a radius as big as I can reach first to the left and then overlapping to the right. If the area is big enough I will do this first in an east west direction across the patio then in the north south direction. It does produce a very flat surface, but I believe that pipes will do just as good of a job with less time and effort. Now that I have an enclosed trailer carrying and keeping straight a supply of pipes seems like less of a problem, it will become part of my system this year.

Limestone and marble are a bit different than most stone chemically, They will readily dissolve into water, not just erode from constant wear of water running over it. It does require a slightly acidic water but average rainwater fits this bill. The smaller the particle the easier it will go into solution, and hence run away. Around here limestone aggregates are used heavily for pavement bases as well. In my opinion (many other's too) it is poor choice for base material. All of our roads are built on MTO granular 'A' gravel, a sand based aggregate 3/4 minus that complies with ASTM C2940. This is what I use to build pavement bases. Lucky for me it is abundantly available in my area.

I would agree with your theory that the clay like limestone bases I have witnessed had an over abundance of fines. This would be due to poor quality control at the quarry and shipping yards. But there is also another issue with limestone, it has to do with the shape of the fragments, more so in screenings than 3/4 size material. The fragments are often more flat than triangular. Flat fragments are difficult if not impossible to compact to required densities. This is difficult to illustrate with words but I will try a little demonstration. Take the fingers on both hands and interlock them to the first knuckle. You have a 1/3 overlap. Now squeeze down the way a tamper might. You can see how flat particles will have a tendency to leave voids in what may seem like a well compacted base. These voids will fill with water, it's unavoidable. Water dissolves limestone (look it up its scientific fact). Have your supplier provide a sieve analysis of the materials you are using, it won't cost anything. Check to see that they comply with ASTM C2940 for base material and ASTM C33 for bedding sand. I can get the percentages passing each sieve and post them if you like.

Poly sand has been a tremendous benefit in the construction of durable pavements for sure. But I learned yesterday of a new product that I will use instead of poly sand this year. But alas my fingers are turning blue now, I will have to fill ya's in later.

A quick afterthought here.... does everyone realize how small the holes in a No. 200 sieve are? If I remember correctly water won't pass through it.

Rex Mann

03-27-2003, 06:44 PM

#200 (meaning 200 threads per inch) is the same as a sheet
on your bed. And, you have to go down to a #325 to seperate silt from clay.

Peace,

Stonehenge

03-27-2003, 10:29 PM

Digin -

I would be interested to see what info you have about Limestone dissolving in water - there is quarry after quarry around here full of limestone, extending deep into the ground, with a good deal of moisture. When quarried there are seams that have been worn/eroded by the passing of water, but they aren't pits of pudding. I'll see what I can find about it dissolving, but admittedly I'm a bit skeptical. I think we may need to clarify the definition of 'dissolving'. Sodium Chloride dissolves in water, but I have a hard time defining something breaking down over decades as dissolving.

As for it being a poor choice of materials, I guess I have to trust that the civil engineers I went to school with know what they're doing when they engineer a project.

And I agree with you on the compaction of flat particles - didn't even need the example, but appreciate it. :)

I can relate to the chubby guy not being able to do what he used to do...

But I do think things would go quicker using pipe as a guide. I know Paul likes using heavy (iron ?) pipe as screed guides, I like using very light steel EMT conduit - his are more expensive and heavy, but they won't move as easily and last a long time. Mine are cheap, light and disposable, but they have to be checked for straightness before each use.

Great information here guys. :scholar: I'll try to dig a little tomorrow to see what I can find.

diginahole

03-28-2003, 07:47 AM

Jeff,

That's just it, it doesn't take decades for smaller particles to dissolve. 8-12% of our base is made up of very small readily soluble particles. For me this seems like too much material to sacrifice. Around here there is an alternative available in huge abundance. I must admit that most of my information has come from conversations like this over many years. I don't have any papers to prove these claims.

When I first started laying pavers they were installed on 6" of screenings as recommended by the manufacturers. I'm sad to say some still use this method. Since then manufacturers have updated their recommended installation methods and more durable pavements have been the result. A number of years ago it was discovered that 'A' gravel results in a more durable base than limestone and the manufacturers again updated their installation guidelines. I chose to follow, not without some skepticism. The information discussed over the years has made sense to me and proved true enough in real world experiences. Limestone bases have far more tendency to rut and distort than sand based aggregate bases. The reasons may well be for other reasons than I believe but my observations do support the theories circulating throughout the industry.

Stonehenge

03-28-2003, 08:46 AM

Because I believe your hardscape market is more developed than the one I live in, the mfg/sales folks there may well be more knowledgable. In general (there are a couple exceptions I can think of), the people here are mainly just regurgitators of info, and have not independently verified anything they pass along to contractors. Most have at best installed one patio or wall (usually at their own house). So I tend to not believe their info to be very credible.

I have seen rutting in paver pavements of several different bases, sand (bedding course) included, and though I also have no scientific data for this, if you have a small grain (like a coarse sand), with even the most interlocking shape possible in nature, if you have a thickness of that material much more than several grains, it would stand to reason that with the application of pressure it one location, the grains will move away from that pressure.

Put another way, would a base of 8", made totally of a coarse sand, be a feasible base? No way. I'm suggesting that 1" may also be much to much. I'll dig a little on the limestone issue and report back here...

Stonehenge

03-28-2003, 09:07 AM

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 (http://www.agf.gov.bc.ca/resmgmt/publist/600series/637200-2.pdf), 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

03-28-2003, 04:23 PM

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

03-28-2003, 04:43 PM

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

03-28-2003, 08:58 PM

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

03-28-2003, 11:29 PM

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

03-29-2003, 02:37 AM

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

03-29-2003, 01:28 PM

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

03-30-2003, 09:57 AM

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

03-30-2003, 12:47 PM

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

03-30-2003, 02:02 PM

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

diginahole

03-30-2003, 02:18 PM

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 (http://www.new-technologies.org/ECT/Civil/humboldt.htm)

Stonehenge

03-30-2003, 02:31 PM

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

03-30-2003, 02:42 PM

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

03-30-2003, 02:45 PM

We need to know what type of soils you have?

diginahole

03-30-2003, 03:11 PM

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.

Stonehenge

03-30-2003, 03:15 PM

I did take a look at that, and it was a surprise to see the vibe plates are not spec'd for most work in clay (though that is for the clay, not the stone). There isn't a single installer in my market not using a vibe plate.

I would have to say that for the area I'm thinking of installing this test pavement will be mostly clay. Though the test area will likely be a total of about 100 sqft divided among the 3 pavements.

But if I recall, the eqpt you have, though bigger than ours, is still a vibratory plate. Not a roller, not a rammer. Does this mean we're all doing it wrong? That spec would seem to indicate that. (However, that spec was made by Vibromax 2000, a mfg of Roller compaction eqpt - is it safe to adopt specs by the mfg of eqpt that would benefit from the specs leaning a certain way?)

Paul

03-30-2003, 03:36 PM

We do have rollers, one is a skid mounted and other is a 9 ton unit.

For clay soils add an extra 2" of base material. If it is just going to be used as a pedestrain walkway then a heavy plate (8000 lbs) should work. again it depends on the soils and conditions.

I agree with Diginahole on the straight edge no gaps under it, base should be graded with a 1% pitch.
I don't know what type of edge restraint you use?

Rex Mann

03-30-2003, 04:10 PM

Jeff,

That 4 inch base thickness is the recommended minimum. The more clay and silt content coupled with freeze-thaw cycles then you need thicker base. An additional 2 inches would be sufficient, And, the ICPI specs on compacted base is just that, compacted to 4 inches not to be confused with 4 inches then compacted down to say 3"

A good way to measure the evenness of the base is a straight edge. If a carpenters pencil slides under then adjust it.

For pitch we use 1 to 2% depending on site conditions and paver location.

When doing jobs where the soil is not virgin then compaction numbers and type of machinery to use becomes very important. However, when doing the typical paver job for most contractors, which I would say is <1000 square feet and is residential, the only fill is usually around the foundation. And, allot of guys will not warranty the parts of jobs within 3-feet of any foundation.

We find a a number of cuts and fills on commercial sites. We make the GC pay for the compaction tests or provide a soils report. To many times we hear "we wheel rolled it" and I cringe. There are other field tests to use for SPD tests. Some are layman's and some are scientific. But, none is as accurate or fast as a nuclear test.

Keep in mind there are two ends to the compaction testing. The first is in the lab using material, either soil or the base, you'll use under the pavers. The second is in the field testing the actual compaction you have applied. The lab results sets the benchmark.

When I teach the ICPI class one of the first things we do as a class is decide what to call all the pieces to the puzzle. Do we call the dirt under the aggregate the base or the subsoil or the sub-base. So on and so forth we go. We all decide on what to call these components to eliminate any confusion. Do you guys what to do this?

Peace,

Peace,

Rex

Lanelle

03-30-2003, 04:25 PM

The first part of this test is deciding on the standards, methods and materials to be used. The part that I haven't seen discussed is how long is this test going to last? Most jobs look great when they are newly completed. The real test is how they hold up over a period of time. So how long are we going to wait to declare a winner?

Stonehenge

03-30-2003, 05:08 PM

Hi Rex, not meaning to split hairs, and I have to take a little time to respond to everything posted since my last post (lots of stuff!), but the ICPI specs do not say anything about 'compacted to' lifts. They just say 'lifts of 4-6" '. Since I can't measure the compacted depth of something until after I've compacted it, it would have to be presumed that the 4-6" lifts would be the pre-compaction thickness of the lift. Is that a fair assumption?

I'm hearing most say that we need an additional 2" of stone to account for soil type and climate. So we have 6" of stone, 1" of sand for the ICPI method, correct?

Also, nobody has weighed in on the geotextile - should it be used? If it is, it will go under each pavement, as geotextile is not what we're testing for this discussion (I believe).

1% pitch is about 1/8" per foot (+/- a 32nd or so). We'll probably go to something more like 2%. I'm sure there won't be an issue with that. The pitch will be uniform across the 3 pavements. I've seen the +/- 3/8" over 10' as an ICPI spec, so I'd like to stick to exactly that for one of these pavements. It will be verified by laser level (mine doesn't have slope, so I'll have to do a few extra calculations, or move the laser level, to ensure accuracy. I've had a few calculus courses in college, so I think I'm trustworthy :) ). We can use the straightedge as a guide (what size?) for the third, where possibly we'll use a different stone (non-limestone).

Paul, I thought one of these was your skid-steer mounted unit: http://coneqtecuniversal.com/compaction.html or http://www.warrenattachments.com/plate_compactor.htm

Rex, having a glossary of universal terms for discussion would be very beneficial, especially for the times when others will go back and read this or other threads. I'm satisfied using whatever terms you'd like - if there's a standard set you use, we'll stick to those. As for lab tests, you're right - nobody uses the pavements made in a lab. Since this will be a field test, we'll need to do all testing using field methods. I'm even up for hiring the nuclear density test to be done (but I may put those results in the Private Gardens to recoup the costs of hiring out that test).

Lanelle, you ask the perfect question...the area where I will have these test pavements will only see traffic when I purposely go there to apply a load. That makes failure less likely for any of the pavements, so we may need to figure out a way to expedite the longevity test. Maybe watering it while running a full wheelbarrow (400#) across the same path time after time? I'm going to need some suggestions on this one.

Paul, I'm wondering about the 8,000# compactor. We certainly have access (I may be in the market for one that does around 18,000), but I'm wondering if that is what most use for pedestrian pavements. 8,000# pretty much puts us into the reversible plates. Rex, if I recall, you use a couple Wacker 1550's and a larger Stone. Digin, I don't know all the epqt in your stable, but I don't think a reversible is in it. We may need to discuss this one a bit more. I'm not seeing a recommendation in ICPI for the size of eqpt to use.

Paul

03-30-2003, 05:32 PM

They leave to type of compaction equipment to the contractor because each area is law unto it's self. Yes we do have a Warren plate for our skid steer, it works better on gravel but has it's problems with sub base.

Rex Mann

03-30-2003, 06:14 PM

Jeff,

The ICPI 4" spec means 4" compacted. All of us have enough experience to know what our compaction factors are for certain materials, machines and lifts.

ICPI does need to clarify some of the specs in their Tech Specs.

For this test I like to see this (just my idea):

Test for vehicular traffic for rutting Pave an area within your shop driveway(a strip)

Use geo-textile because your environment calls for it

Use your standard edge restraint

Use a 4X8 Holland stone with a running bond pattern(has the least lock up and the least ability of patterns to bridge settling)

Use your standard install materials and practices for area #1

Use limestone base with max 12% fines with a ASTM C 33 sand AKA concrete sand for area #2

Use just sand or screenings over soil for area #3

Just my ideas.

Rule of thumb on rutting/settling I've discovered through talking with others in the industry and experiences.

If it settles within the first month a problem with the sand
If it settles within 2-12 months problem with the base
If it settles after that a problem with the soil

Just a very general rule of thumb but in my world it is trustworthy.

Heres what I find most people can agree on for the "common lingo"

soil = soil
base= aggregate, limestone, crusher run
sand bed=bed pavers are set in

Peace,

Stonehenge

03-30-2003, 06:54 PM

I don't think we'll be able to do a portion of the shop drive, as we don't currently own the structure that houses us. Also, for vehicular traffic we'd have to go with the specs for vehicular traffic. I may be able to talk to a paver dist, as we're going to be doing a pretty big display for them - maybe we'll throw in some test pavers at a drive entrance...But unless I get the go-ahead there, we'll have to do something else to speed up the longevity test. Rex, I like the idea on the pattern to lay the Holland - that will be a good test of the base.

Compaction - what does everyone else think about the eqpt to be used? Wacker 1550? 3345?

Rex Mann

03-30-2003, 09:24 PM

We use a Waker 1550 for both base and compacting the pavers. Use do base in 2 inch lifts.

We show a movie, with a company out of the Chicagoland area installing a driveway, during the ICPI class. And, they use a larger reversible diesel compactor and they are doing 2 inch lifts.

I think 95% of the companies do not use the right compaction equipment. And, its not coincidence that 95% of the failures are due to improper compaction.

I say use the 1550. It seems to be the standard across the country.

Peace,

Stonehenge

03-31-2003, 07:52 AM

Ok. Digin, Paul and Lanelle, you OK with that?

I think someone has asked about edge restraint - here's a link to the stuff we use: http://www.curv-rite.com/prod02.htm

diginahole

03-31-2003, 08:47 AM

It's good by me. I think it's around a 3300# unit, smaller than recommended by ICPI but I agree the most common sized machine in the residential sector. We would use a similar size machine for pedestrian areas.

I think what's more important than machine selection will be that the procedure for each installation be the same. If there will be nuke testing each section should be brought to 95% SPD and the number of passes recorded. The quickest to achieve 95% would gain an advantage in the test. If nuking is out the bases should be subjected to exactly the same number of lifts and passes and the last to show signs of failure would be given the advantage.

Stonehenge

04-01-2003, 01:23 PM

Ok, give me a little time and I'll put together some specs for these three pavements. Once they're up we can tweak them if need be.

CountyMaterials

05-30-2003, 12:32 PM

Thanks much to whoever put the links on for the ICPI site, I am actually gonna sit down and read them.

Any way, not sure how much my information will help, but I will tell what we recommend. (By "We", I mean the company that I work for, we sell the manufactured products, pavers, retainging wall block, etc.)

Our literature that we hand out recommends using 4"-6" for base material and use dry concrete sand, not to exceed 1" in depth. Slope is 1" every 10'.

Now, that is what we tell the "Do-It-Yourself" and "Weekend Warriors." I am the Landscape Rep for this area and I don't know of anyone off the top of my head that uses sand with their bases, even 1". Not sure what you do though Stonehenge. However, that is not to say that noone uses sand, I just know of them. The landscape company that I worked for, used sand (approx. 1") about 3 years ago and then stopped doing it. The reasoning behind this is because the jobs that he used sand on, he had to repair a year later. His compaction method is still the same. Using a Wacker plate compactor like the one mentioned earlier and compacting every 2". Now, that being said, he also puts in more base than is recommended. For instance, most paver patios and walkways will have a minimum of 8-10" of base. On driveways, he would use 20" base including geogrid. He always installed into us that there was no such thing as too much base. Maybe more that necessary, but not too much.

Me personally, I just don't trust sand. Maybe I am biased because of previous history with it, but I just don't trust it.

Anyway, not sure if this information added any value, to the discussion.

Paul

05-30-2003, 08:19 PM

CountyMaterials, what type of failures did you have?

CountyMaterials

06-02-2003, 10:02 AM

The same on most every job, sand wash out, dips, excess movement. I actually just talked spoke with one of the guys this morning because we were talking about a driveway application that called for some sand. Neither of us like the idea and he mentioned that he has been fixing all the jobs from a few years ago that used sand. My understanding for not laying pavers on screenings is because of the salt causing effloresence, specifcally with cement pavers?.?

Rex Mann

06-02-2003, 12:01 PM

The sand used under pavers is to be 1 to 1 1/2 inches thick. It is also commonly called concrete sand. Do not use mason sand. If this type of sand is used, then you are likely to have movement and shifting.

Efflorescence is a natural process for all concrete products. There are ways to minimize it, but not eliminate it. Screenings have over 12% fines passing the # 200 sieve. Fines hold moisture. Moisture facilitates the efflorescence process.

When I took my first ICPI class it dispelled many of the same "wives-tales" I had about why we did or did not do things a certain way.

If you ever have the opportunity to attend an ICPI class, or better yet, sponsor one at your place, take it. And, if you do sponsor one I would be happy to come back east and teach it.

Peace,

Rex Mann

Stonehenge

07-06-2003, 08:12 PM

Ok - I have an update - we may get to the construction of this test patio tomorrow. As I re-read this thread, it sounds like we want:

Geotextile under each test area

Hollandstone, running bond pattern.

1 test pavement with just our usual screenings as base

1 test pavement with 3/4-, 1" bedding sand (coarse concrete sand)

1 test pavement with just sand (?)

Each test area will be excavated to the same depth (8-9" below the top of the pavers).

Each area will be compacted in equal lifts of stone (or sand for the all sand prep), an equal number of times.

Each prepped area will be compacted with a Wacker 1550 vibratory compactor.

The same joint sand will be used across each pavement (no polymeric or organic binders will be used, to allow water to pass into the base to further test it's stability).

The same edge restraint will be used for each of the three sections.

Ok - I think I have everything down. Unless someone has something they think should be changed, we will tackle this project sometime this week, possibly tomorrow. It will be photographed and videotaped.

We will continue to test the pavement periodically during the season, by applying water to the pavement then subjecting it to loads. Measurements of deformation of both bond lines and base prep will be taken.

I haven't decided how I will make this information available. Seeing as we're incurring some costs to run these tests, I may opt to post the results in the Private Gardens.

BJR

07-08-2003, 01:25 AM

I can't believe that you are all having this debate.

We, as an industry, had this discussion about 20 years ago in Australia.

We all use sand under our pavers as detailed by your ICPI method. Our standards were put out by the Clay and Masonry Segmental Paving Association. I will see if I can find a link to post.

Nearly every aspect of our construction has an Australian Standard or Industry Standard that you have to work to.

If not you may loose your licence to operate.

Stonehenge

07-08-2003, 07:31 AM

There are some here, myself included, that do not believe sand to be the answer to a stable base. I'm of the opinion that the sand aids in fast installation, but not stability. But I'm open to new ideas and discussion, which is why I want to conduct these tests.

I hope that in those 20 years you've also continued to test and modify your procedures to make things even better today than they were 20 years ago. I'd be interested to hear what changes have come since then.

Have a great day,

Jeff

BJR

07-09-2003, 03:59 AM

I have found that the basic design I use for segmental paving is superb. In all of the thousand os sq metres of pavers that I have laid with a compacted sub-base of what we call 20mmDGB (Road Base the same base used when constructing roads), this varies in thickness depending on traffic use, and the bedding layer of 30mm concreting sand, I have never had a failed job. That I know of.

I have however had failures when using different techniques.

One was a job for a local council that decided to construct a road deviation to stop drag racing along a straight stretch of road. The base was concrete, and then 30mm of concreting sand to lay the pavers on. I had my concerns from the beginning, because I have noticed on previous jobs that when passing the plate over the pavers laid on sand on a concrete base that the first pass beds the pavers in and the second pass actually loosens the pavers. I concluded that the concrete base did not absorb the vibrations as well as the road base. From then on I only passed the plate over the pavers once.

My concerns for this job were founded when the paving started to fail. It became loose and moved around, thus opening the joints. I repaired it 3 times without success. The Council finally lifted the paving and concreted the area.

Also back in my younger days there was a contractor who constructed his pavements with a fine road base. He would compact a 100mm (4in) layer first then place a thin loose layer on top to lay the pavers in. His finishes were never as even as other contractors and the jobs on steep drives always seemed to move.

There are projects around here that are tens of thousants of square metres in size, one being at the Olympic site in Sydney and others on shipping terminals where large folk lifts and trucks weighing over 40 tonne work on the pavers 24 hours a day. All of these jobs are on a road base and sand bed. These pavements are still in good shape today.

That little bit of sand that comes into the joint from the bottom must to something to strengthen the pavement. It must strengthen the paver interlock more than the fine sand that we vibrate into the joints.

So if something ain't broke why fix it.

Sure I have improved my techniques over the years, like screeding to a sand line, IE making grooves in the sand at either side of the job and screeding to these. We call it freehand screeding. It comes in handy when screeding jobs such as rolling driveways. I have improved the way we do the little things, but the basic design always stays the same.

Who am I to question thousands of dollars and years of research by qualified technitions.

Rex Mann

07-09-2003, 11:24 AM

BJR,

Australia has had many more physical scientific studies on paving stones then any other country in the world. I'm positive your installation techniques have come about from Dr. Brian Shackel's work in this area. I would not hesitate to say he is one of the most respected people in our industry.

I once had the pleasure of hearing him speak at a seminar. :)
Then I was able to sit at his table during lunch.:D What a day!:woot:

He told a story of a simple lab test he conducted on vertical lockup.

I'll try to explain it the best I can.

They, him and some of his students, constructed a 1.5meter X 1.5 meter box using 2x4 lumber. It looked like a band, not a cube. they used one piece per side.

Next the put in 4x8's in a 90 degree herringbone while the 2x4 band was on the ground.

Next, they lifted up the box with a hoist to waist level.

They proceeded to hammer pavers out one at a time in preselected locations. Like the game "Don't Break The Ice"

After 5 pavers were removed the whole thing came crashing down.

For the second test they swept concrete sand, jointing sand, into the pavers from the top only.

Next they did the same thing. Using the same location of the pavers as they had in the first run.

This time 13 pavers were removed until it failed.

Then he went on to explain why he got the results he got in both scientific and layman's terms. He was not some old timer or piece of literature telling me to use concrete sand with no way to back it up. He tested his theory in the lab getting the same results time-after-time.

I was sold on using sand before I ever met him, however now I knew why I was using sand. The ICPI was about 2-years old when this happened. They were still getting tech-specs and classes in place.

Check out Dr. Shackel's web site.

http://www.brianshackel.com

Peace,

Rex

Stonehenge

07-09-2003, 12:29 PM

I'll certainly have to check out that site. Thanks for the link, Rex. :)

Though the vertical lock of joint sand has a role, I have more of an interest in what goes below the pavers for the moment. If this test was similar to the game 'don't break the ice', it doesn't really address the base prep. I'm sure Dr. Shackel addresses it with other tests and other texts, but this test does not seem to apply to the question of base prep.

In any case, to your point, BJR...Who are you to question engineers who design specs for this work? Who, indeed. By your own statements you laid thousands and thousands of square meters of pavers - I think that makes you uniquely qualified. I guess having grown up with a PE in Mechanical (my father), married to a Chemical Eng with a Master's, and taking two years worth of engineering courses myself I'm a bit less mystified by engineers and their methods. What's more, I recognize that they are subject to many, if not more, of the same human character flaws as the rest of us, making their word (the PhD's, that is) not gospel, but the word of someone with a few more years of schooling, and a few less of practical experience. Which one is worth more? I guess it depends on the person.

I was in contact with the Civil Engineering department at my own alma mater last spring to get input on installing pavers over an asphaltic base. I was a bit surprised at some of the specs and information I received, thinking 'Jeez, I know more about this than this PhD does!' And this was someone that specialized in flexible pavements and taught this at the university level, at an engineering school that is among the top-ranked engineering schools in the Midwest (USA).

Am I saying I'm smarter than Dr. Shackel? Not at all. But I think that you do yourself a disservice to presume that you are simply the grunt labor, and they are the brains when it comes to hardscape design. I'm not fond of taking someone's word for something; I like to gather a bit of empirical evidence myself. So in running this test on this site, that's what I'm doing.

And then I'm sharing the results with everyone, that everyone might benefit. We may well end up singing the praise of the ICPI, Rex and Paul, and now you, BJR. But I want to see for myself before I start warming up my voice.

And I don't have any interest in any particular outcome - I just want us to be doing things the best way we know how. I've wanted to do this myself for awhile, now I get the chance to show everyone the results.

BJR

07-10-2003, 04:09 AM

I, by no means seel myself short. I also started mechanical engineering at University and have recently found out that I have an IQ of around 150. Pretty unbelievable.

But I believe that the way I lay pavers is the correct way.

I am not quite sure exactly how you prepare your base and what you lay your pavers on. I believe that the entire pavement has to be flexible. I do not like the laying of pavers on sand over concrete on heavy vehicular traficed areas. I believe that they should be glued down, with suitable construction joints.

The way we prepare our base is to compact the ground first. Then a layer of road base is spread in 100mm layers and compacted to a standard specified for the project. In larger projects we actually have the compaction rate tested. Then we screed the concrete sand bed. Lay the pavers with a 2-3mm joint. edging is varied depending on the job. Then the pavers are straightened and a fine rendering sand is swept into the joints and a layer just enough to cover the pavers is left on. This must be powder dry. Then a vibrating plate with a urethane mat is passed over the pavers twice in overlapping runs. The sand is then swept off.

I have tried many different ways of doin paving, including one ignorant attempt to lay them into wet concrete. I was young and thought I knew better.

I always came back to the above method.

150! I can't even spell properly.

Still, I guess there has to be something in my big boof head.