> -----Original Message-----
> From: Met History
> Sent: Saturday, August 17, 2002 9:43 PM
> To: [log in to unmask]
> Subject: And, please explain...
> 
> 
> ...why (Dan, or was it Ken?) you have to mortar the joints of 
> Belgian block in street paving.   Why not have them laid in 
> sand, if its only a parking strip?  Then you can get more 
> ground water for the street trees, and pickup/takedown is 
> easier for utility access.  Or is it? 

Ken said mortar between. I (and Ken) said concrete road base below. You
didn't specify "only" parking strips. You're quite correct about the
benefits of doing it without concrete base. 

It can be done without a concrete base below, but it takes extensive
preparation to make sure that the road bed does not settle. You have to
deal with soil inconsistencies through relentless compaction, proper
sub-surface drainage to avoid freeze/thaw heave, with geotextile fabrics
in the right places to keep the stone dust setting bed from migrating
through the gravel sub-base, careful setting of the blocks, making sure
you get them set tight with minimal joints and work the stone dust
between all the joints...a few missed joints, or half-filled joints, and
it will start to loosen up. Like most endeavors, there are fewer capable
designers, contractors, and craft folk around that can actually
successfully do it than there are projects. Therefore, you end up with
failures where the design/work wasn't done properly. DOTs tend to only
remember the failures, which then turn into maintenance nightmares. And
even when done right the first time, when they return for your utility
access, the folks that put it back don't know what they are doing and it
ends up a mess too.

And of course, those street trees you are watering through the paving?
Their roots naturally go to the water. Then the roots start to grow
because they are finding the water. They get bigger, and bigger, and
bigger. The road heaves. DOT gets mad and says "No more belgian block
parking strips."

___________________________________________________
Dan Becker,  Exec. Dir.     "What's this? Fan mail
Raleigh Historic             from some flounder?"
Districts Commission         - Bullwinkle J. Moose
[log in to unmask] 
919/890-3678

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