OOps, sent original back channel by mistake, this is a response to
Christopher:

----- Original Message -----
From: "Leland Torrence" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, March 24, 2000 5:13 PM
Subject: Re: Re: The Frick's bluestone sidewalks - RIP


> Blue stone side walks are notoriously expensive to maintain.  The stones
are
> usually laid in packed/tamped stone dust, however, stones vary in
thickness
> over 100% in most cases.  The process to install is labor intensive,
> requiring lifting and replacing the stone. Many of the older walks had
> bigger stones of  at least 200 lbs. Rain water, freeze-thaw, salt (don't
> know if they used it then) do a number on the substrate and stone causing
> the stones to lift, pitch and rock, creating a surface that is uneven and
> hazardous.  In an urban environment, heavy objects often break the corners
> and sometimes the entire stone.  The stone also delaminates and shale's.
> Hence, annual or biannual preventative maintenance involving resetting and
> replacement.
>
> Best,
> Leland
>
> PS  Thanks for the books.
>