Day 5 (continued)
They'd brought yet another load of stone, but a small one which easily
fit into the short trailer. It almost looked like sand, but this was
rather special stuff: "chip stone" for paver joints, the magic permeable
material that would fill all the gaps between the pavers and lock the
entire structure together.
[Not to be confused with "cheap stone", as it sounds when uttered with
Latin ethnicity added! The stuff is not particularly cheap, as it's a
somewhat specialized item. And technically, almost everything that
went into the open-graded bed could also be called "chip stone" which
really refers to the angular style rather than the specific size.]
They backed this in just over the end of the driveway space and dumped
it all right there. The surface wasn't really ready to take traffic, so
they didn't want to try and play games with the truck and trailer as
far as distribution as that would probably really screw with the paver
alignment they'd just spent a while eyeballing.
Instead, they just started tossing shovelfuls out into the field to
get the spreading process started.
Where it landed immediately developed obvious little holes, as the chipstone
was already starting to fall into the gaps. A quick test confirmed that
it drops into there quite easily, which is sort of the whole point.
Now I knew all the grades of stone used in this, and could make a little
layout showing the relative sizes. And a detail of what the pavers look
like when cut apart. It's all angular crush instead of rounded, for the
self-locking aspect described earlier.
Further distribution was done by simply pushing piles of the chipstone
with the back of a rake, all the way down to the other end and obviously
losing some portion down into the still-empty slots.
Now came the "sweeping" part that's more familiar in pavers jobs,
except that this *wasn't* the usual fine impermeable sand. There were
clearly specific broom techniques to most effectively make the stone either
drop into the slots or get pushed farther along, and it was all a fairly
Sweeping basically filled the cracks, but there would be a little more
to it than that. First thing was to get all this stuff evenly deployed,
which took a while.
In the meantime, the truck and trailer went back out to fetch a load
of loam for the surround. I was still being kind of impressed with
the just-in-time materials delivery aspect of a lot of this...
Now came a very gentle application of the leaf-blower, throttled fairly
far down and in very specific directions, to push the remaining chipstone
down to the other end and leave the street-end area clear for its last
The subtlety here is that once the slots are full, sweeping in any
direction tends to pull stone back *out* of them and scatter it across
the surface, where blowing at a shallow angle tends to push the isolated
stuff on top away and leave whatever's trapped in the slots alone. There's
a definite sweet-spot of air velocity that gives the best separation here,
and it gets even more interesting when stuff fallen from the trees
gets mixed into the picture too.
The next stage of compaction was rather magic. It wasn't really to
squash layers down anymore, as plenty of that had happened, it was to
settle the chipstone down as far as it would go into the slots. The
best way to express how this worked is a
from the process. Watch closely right next to the compactor
plate and you see the chipstone simply melt away and vanish down
into the slots.
I wonder how they did this back in the days before vibrational compactors?
Time, I suppose, would eventually tend to settle material as we know
all too well that gravity sucks, but probably far less optimally than
giving it all a good shake like this. A few of the chipstone pieces were
just long enough to bridge across the gaps, particularly where the locking
nubs were, and this would clearly bang those loose and let them fall.
I suppose you could do it by hand with a lot of rubber-mallet work, but
that would be incredibly tedious and possibly leave the pavers more
misaligned than they should be.
This left the slots nicely settled down but now not quite full. I went
around and thunked on a few with the rubber hammer just to test if any of
it would settle even more, and it really didn't.
A final pass of sweeping-in brought everything back up to surface level
and finished the lock-in process. And just like that the driveway was
ready to bear vehicles, no curing or drying or any other waiting needed.
So the first vehicle onto the new structure was the guys' truck, to get
the trailer to the back end where they'd dump the loam supply. A lot of
it would be needed right here at this corner, which despite its two-inch
downward grade compensation would still need quite a bit of backfill
Besides, they needed the trailer again to go fetch the asphalt for
the street connection. The head guy was originally thinking that
asphalting would wait for the next day, but there was still quite
a bit left of this one so he decided to do it that very afternoon.
Now, the thing about hot-top is you have to buy it by the ton, as
that's the minumum amount they'll sell you. We wouldn't need nearly
that much, so I was trying to think of anywhere else we could use
more of it -- extra surround on either side of the driveway, or maybe
even to bulk up the neighbor's little water berm for him. The project
manager had been by in the morning, and we'd discussed a few different ideas.
One of my major concerns was snowplows. I know how they drive around here.
With the pavers laid slightly into the line of the right-of-way like they
were, I could easily envision
a plow coming along and snagging the corner bricks here and
sending them flying. This needed some kind of protective approach to
at least guide a plow blade up and over and not offer any resistance --
because at the speeds they sometimes blast through here without being
able to see exactly where the road edge is, the plow would likely win.
The other connection detail I wanted to make sure was right was water
management at the high-side corner. I had previously built a small dirt
berm across here to kick water coming down the street outward, but that
was long since trashed from all the activity ... but now we had a chance
to rebuild it in nice impermeable asphalt instead! Very entertainingly,
the best way I could come up with to explain what I wanted was to start
building the basis myself. Rather than the lead guy wasting his time
fussing about this, I sent him off for the asphalt run and told him I'd
clean up this spot the way I was thinking and we'd engineer it the rest
of the way when he got back.
The guys didn't even look at me funny when I grabbed a shovel and started
slotting out the path that would be the new berm's foundation. Asphalt
doesn't work well in thin layers -- for lateral solidity it needs to be
at least a couple of inches thick, so it would basically need a shallow
hole down to firmer earth under where it would go here. I had to
stop and get out of the way for a bit while the other guy finished
an additional cut down the slot -- widening it even more to trim back past
any hint of the previous damage, and giving a little more room for a new
gentle up-sweep to match where the pavers began.
This felt great. Now I was actually working *with* the guys, instead of
just being that gadfly with the camera running around the jobsite. While
the previous week had been wonderful dry weather it had become hot and
humid again today, and we were all sweating bullets. I didn't care, I was
totally in down-and-dirty design mode and knew what I wanted here. And
the asphalt was due back any time now.
At the other end on the low side, the PM and I had settled on constructing
sort of a wedge to extend away from the corner a couple of feet as a
protective buffer. Appropriate cuts and digging were made in preparation
The asphalt arrived back right in time and they started laying it in --
first across the main connection, and then we'd see how much we had left
for my little creation at the other end.
So this is what a ton of asphalt looks like. The pile in the trailer
was slightly elongated toward the front but no more than maybe five feet.
It's dense stuff so that actually doesn't amount to a huge volume, but it
was clearly still way more than we'd need for all of this.
Time to oil up the Magic Shoes! These looked distinctly home-built, out
of wood, but like the pair that was used on the street job they'd be the
right tool for compacting down small runs of asphalt. The little squirt
bottle of diesel was plenty to lube up all the tools they'd need here.
If you're finding yourself asking "...diesel??", my revelation about its
use in asphalt work came from the
roadwork page. Basically, a
The berm material was laid just slightly high, and then carefully "walked
down" to create the match and slope we wanted.
He applied a nice humped shape to my little creation over here, which
was long enough to fully reach back to the rock where my old dirt berm
had started and after my somewhat enthusiastic trenching, had quite a bit
of depth now. The street-side corner opposite the pavers was actually
where the old berm had begun and was still intact, about where his left
foot is, so that didn't get cut away but simply connected to and
I also re-shaped the surrounding dirt to pretty things up as part of
post-cleanup later, and in the process raised the inboard-side level
of the area even more. Runoff *ain't* gettin' past this.
So here was the whole resultant design: matching the road to the pavers,
restoring a good water-deflector upstream, and bedding the most vulnerable
corner in healthy defenses. We wound up using maybe half the asphalt
all told, a respectable dent in it but still with quite a bit left over
and still plenty hot.
This didn't faze the guys at all. In fact they've got a clever way to
manage this, aided by the fact that they still had a big pile of other
stuff to collect for disposal too -- the heap at the other corner was
by now a mixed-up mess of aggregate, dirt, bedding stone, sand, and bits
of concrete and it all had to go. What they did was throw in a thin layer
of that behind the remaining asphalt, and then the guy got in there and
started *transferring* the asphalt on top of that. As the asphalt pile
worked forward they threw more of the new layer down. This would keep
the asphalt from sticking to the trailer bed itself once it cooled,
and they could then easily dump/shovel the entire mess onto the junk
pile back at the shop.
The head guy was semi-complaining that every job invariably winds up with
a similar mound of excess *stuff*, but they just collect it and every once
in a while larger loads get shipped off to someplace that can beneficially
recycle most of it into new products.
At some point I thought to do a quick "hose test", wetting down one or two
of the pavers to see how water would flow. Well, even with a healthy stream
water goes to the edge of the paver it's on and just *disappears* right
over its edge. It's quite surreal, when intuition wants to think it
would flow onto the surrounding pavers.
It'll be interesting to see how this permeability fares after a few years
under the pine trees. The maintenance guides hint that in extreme cases
of clogging removal and cleanup of joint material can be done, but
shouldn't be necessary very often.
The weather had started to look fairly threatening that afternoon, and
checking the radar revealed some pretty serious crap coming at us from
the west. We had been very fortunate that it all held off as long as
it did to get all this stuff done, and an awful lot *had* been done
that day. But a little later the sky built up dark and black and
we got a serious downpour, giving all this stuff a nice brute-test.
The guys were hunkering in the truck and I was sheltering at the
side door, but I could mostly see that the new berm was already doing
its job and water was staying well clear of the pavers on its way by.
So at this point the driveway itself was pretty much done, and all that
remained was for concrete to finish curing and asphalt to cool and harden.
Ribbons were left up across the entrance so nobody would happen
to nose in across the fresh hot-top, and I wouldn't be parking on this for
another night. No problem, we all wanted it to be as perfect as possible.
The next day was nice and clear, and the pile of loam had managed to get
tarped over just before the rain came so it didn't turn into a soggy mess
of muck. Now it was time to spread that around to finish off the edge.
This was no more complex than matching a slope from the nearby ground
up to the edge of the pavers -- in some areas, considerably up. They
didn't pack this down at all, just left it sort of soft as it had
been applied. I think the usual expectation is that it would get a
few handfuls of grass seed and over time, magically restore lush lawn
continuity right to the driveway.
With that in place, another pass around the edge to sweep in some
last bits of chipstone could happen and not have it all just fall out
the ends. This required a little artistic broom work to keep the
grey stuff and the brown stuff separated.
Aesthetics were still figuring largely in all this trim-up work; the
narrower slot at one spot in the curve "soldiers" [seen in the closer
pictures during its construction] was bugging the head guy so he fired
up the saw and buzzed it a little more open to match the others and
then it could actually accept filler as well.
Whatever was still kicking around on top near the end of sweeping was
persuaded toward the middle into a pile, and that's all that was left.
Rather than waste one of their bigger buckets on collecting this for
my spare stock I scared up a coffee can, and a generous amount to have
on hand neatly filled it without too much organic detritus riding along
with. In theory I wouldn't need a whole lot for ongoing maintenance.
The gaps were so full right now that there would be no harm in losing
a little to ongoing use and clearing and possibly a little bit of further
settling over time, so this would probably last effectively forever.
But if I needed any more of it later, I could easily go
buy it in bags
from a nearby stone and masonry supply place. The PM showed me this and
his recommendation on efflorescence cleaner, in case I wanted to attack
the random whitish patches on some of the pavers. [Basically, weak nitric
acid.] Techniseal markets a whole line of paver care products [as does
Unilock themselves], most of them geared toward the impermeable type of
setups where the aim is to have a *sealed* structure so I'd have to be
a little cautious about any sort of cleaning effort.
The efflorescence is just a natural result of concrete curing, and after
a little research
it seems like the best strategy is to just let time take its course and
it'll go away by itself in a year or two as long as salts are kept off
the driveway. All of the pavers would
eventually lighten in color anyway once out of their factory-fresh bundles,
so I wasn't too worried about it.
In fact, efflorescence or no, it all looked gorgeous. Several neighbors
had passed by the ongoing project and stopped to admire, as it's such a
radical and frankly upscale change to my old patch o' dirt. "It's totally
Hollywood Boulevard", commented one. And as mentioned before the
graceful curved bit, now clean and bordered by rich dark loam, really
added a nice touch.
One caveat about the permeable system is that under normal circumstances
you don't really want to
sweep or rake at all, because it will easily dislodge the joint stone.
I was glad I'd already researched the whole leaf-blower thing a couple
of months before, as that would be an important tool in ongoing care
of this. I wound up getting one of
a nice lightweight cordless unit with variable speed. With that I'd
be able to dial in that delicate sweet-spot between pushing organic
stuff and pushing chipstone, and while I don't actually mind trailing
a cord around for some things it would also be much nicer to take an
un-tethered tool up around the roof and gutters when it came time to
launch all the oak crap overboard.
And with that, it was final cleanup time. They'd brought along a pressure
washer today, with the idea that it would be the best thing to get rid of
the remaining bobcat tracks and scrubbed-in dust. First thing he attacked
was the concrete saw -- this couldn't have been good for the engine, I
thought, but apparently he does this all the time to get the dust out
of the works. Well, it's a Stihl, I guess it can take it.
Then he started on the road, and the spray did lift a lot of the ground-in
stuff away nicely but it took a bit of persistence. Not like it covers
a large area at a time.
Once again, the new berm was doing its thing nicely. Even with all that
new drainage capacity under the pavers, probably with enough capacity [as
postulated by the PM] to suck up both gutters' worth of roof load too if
the downspouts were on that end, no reason to abuse it!
The geekdom never stops
At some point the washer ran out of gas, and they grabbed the nearest
can to put a little more in -- asking each other, "this isn't diesel,
is it?" beforehand ... they seemed confident that it was good gas, but the
jug might have had anything in it prior to whatever its current contents
were so who knows. The washer started to run on this but soon conked
out and seemed rather unwilling to restart and keep running again.
The lead workman fiddled with the fuel valve and carburetor a bit without
getting any more than a few more halting coughs out of the engine, and
exasperatedly gave up for a moment to wander off and find different
tools. But something about the *way* the engine had died and how it
was now behaving -- starting with a couple of healthy surges and then
dying again -- got me thinking something had coincidentally gone wrong with
the throttle governor linkage, likely unrelated to the refueling. I do
have some experience with these things so since no further progress seemed
imminent I sat down next to the washer for a closer look. The linkage moved
okay; what we were getting didn't sound like a fouled plug or anything,
and if something had started restricting fuel flow then it was still
trying valiantly to run on whatever made it to the bowl so it probably
wasn't bad gas either.
One way to debug governed systems is to un-govern them temporarily and
give it a stable throttle setting, so I held the linkage steady and gave
the starter an experimental tug or two. It started. And it stayed running,
with me in theory holding a fixed throttle opening. I was like "...huh??"
but then looked around for the guy and waved my free hand in the direction
of the wand -- perhaps cleaning could continue as long as I now didn't
move for the duration. I was right. I sat there on the street with a wet
ass, embracing his pressure washer while the rest of the crud got flushed
away. It was a moment of the *oddest* geeky triumph, and although the
camera was tucked inconveniently under my busy arm I magaged to twist
it around enough for the picture.
After the street was done he sort of shot the spray long and high over
the driveway, to mist it down a little. Said it would look better,
for when they went to take their own completed-project pictures.
Wetting does indeed temporarily hide those efflorescence spots...
As he was finishing with the washer and to a noncritical point with it
I was experimenting a bit, and found that when I moved the throttle
linkage back and forth a little the engine output *didn't*
change. What I surmise is that whatever connects the little cam I
was holding to the throttle flap itself had broken in some way, and
the fact that I was holding it all against rattling was probably the
only thing keeping things running. Mysterious, because it's just a
shaft down to the flap itself. Whatever. He figured on just getting
a new carb for the thing and bolting it on, rather than trying to debug
the old one.
So here's my "after" shot, along with the "before" again and the
obligatory animated-GIF crossfade hack between them. The light
angle was almost the same -- it was still only mid-morning, and
they were done and packed up and out of there before noon.
The car seemed entirely happy in its new digs.
What the car could discern that I couldn't by eye was the a gentle
slope toward the rear, partially from dropping the grade at that back
corner. It would just barely roll backward in neutral. So maybe I didn't
get my *dead* level mid-field but it was certainly level enough for any
sort of work I'd want to be out here doing. If you look carefully at the
"after" shot [which itself is a little tilted anyway] you see a slant down
to the right at the street end, and down to the left at the back -- the
whole assembly actually goes through a slight camber twist through the
length, which winds up as the best match to the surrounding terrain.
So in effect, the center area is plenty level enough. And heck, if somehow
the permeable joints did all silt up way in the future the part nearest
the house still has a correct pitch away from it.
As I mentioned the loam had gone down very soft and uncompressed, which
I didn't see as quite what was needed. It wasn't helpful to step off the
edge of the pavers and sink deep into that dirt, so I wanted to actually
go around and compress it significantly and add more to make the whole
surround a much more dense thing.
This bizarre crossed-up maze of deck screws is part of the solution.
It's not Thor's mighty redneck hammer of doom, but it is my mighty
redneck wooden dirt-tamper which is simply a handle attached to a
bit of 4x4 but it had to be effing strong and thus overbuilt. I could
have used one of those typical iron dirt tampers [they even had one] but
wanted wood to avoid chipping the pavers when I invariably tagged the
edges. With this and its more suitable face shape, I could go around
whacking down the loam which obligingly subsided a good inch and
more around the thick part in back. Raking a bit more up from the
outer edge and re-tamping built up a nice dense pack right against
the edge of the pavers, which would also help contain the minor
leakage of chip-stone out the ends.
I'm sure a whole creative variety of weeds would soon be growing
out of it anyway. Grass seed?? Bah. That means more mowing. If anything
I'm trying to encourage that nice moss from the backyard to take over.
Days 1 and 2
Days 3 and 4
Day 5 (first part)
Bonus section: extraction technique
Up (main house pages)