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Re: Thanks guidance mechanical etc. - preoccupied lime mortar'ing

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Bob La Londe <none@none.com99> writes:

> On 8/23/2026 3:25 PM, Jim Wilkins wrote:
>> Elsewhere I've read that we still aren't certain, we have the final
>> product but are unsure of the raw materials or mixing process. For
>> instance the properties of modern concrete vary with the amount of
>> water in the mix.
>
> That's what I heard, and what I was getting at.  I wondered if you
> were aware of some newer information on the subject.

"self-repairing" - seems yes.
For natural stone buildings, there are several reasons cited for using
lime-mortar, of which "self-repairing" is but one, albeit crucial.

Zooming to a big context - stone buildings have been reliable for
centuries into millenia...  Then we have the "panacea" of Portland
cement mortar - and in a very few decades we are seeing a rash of
problems.  Mysterious absent before.  Okay there wasn't Portland cement
mortar before the second industrial revolution - essentially the 1880's
and strongly into the 1890's (?) - but the overall view is builders of
old knew what they were doing; funnily enough, now we care to look back
and consider the matter.

Some key characteristics of a mortar for natural stone, as I have
gathered:
* must not be harder / stronger than the stone it is joining - else the
stones will crack with {thermal cycling, fluctuating moisture levels,
settlement of the building, etc.} (all dimensional changes)
* must do the right thing with moisture - not let too much in, and let
what shouldn't be there out
* must self-heal with settlement and flexure of the building - given a
stone building is flexible and historic foundations despite being sound
not being the stiff almost immutable hard raft of modern poured concrete
foundations (the "modern" building is almost floating free of the
dynamics of the ground it is on (?)).

What I am seeing is that a natural stone building with Portland cement
mortar pointing will develop a number of long cracks rising or
zig-zagging across extents of wall.  Contributing to moisture / water
problems with the building.
It is my impression (I am at at early stage of learning) that a natural
stone building on a natural good but somewhat dynamic foundation will
have distributed flexure and the lime-mortar will self-heal, not showing
"failure of the pointing".

I am at such an early stage of learning.
There is not basis by which I can express strong opinions.

Regards,
Rich Smith

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Thread

Thanks guidance mechanical etc. - preoccupied lime mortar'ing Richard Smith <null@void.com> - 2026-08-23 06:44 +0100
  Re: Thanks guidance mechanical etc. - preoccupied lime mortar'ing "Jim Wilkins" <muratlanne@gmail.com> - 2026-08-23 07:45 -0400
    Re: Thanks guidance mechanical etc. - preoccupied lime mortar'ing Bob La Londe <none@none.com99> - 2026-08-23 09:52 -0700
      Re: Thanks guidance mechanical etc. - preoccupied lime mortar'ing "Jim Wilkins" <muratlanne@gmail.com> - 2026-08-23 18:25 -0400
        Re: Thanks guidance mechanical etc. - preoccupied lime mortar'ing Bob La Londe <none@none.com99> - 2026-08-24 12:19 -0700
          Re: Thanks guidance mechanical etc. - preoccupied lime mortar'ing Richard Smith <null@void.com> - 2026-08-25 10:45 +0100
            Re: Thanks guidance mechanical etc. - preoccupied lime mortar'ing "Jim Wilkins" <muratlanne@gmail.com> - 2026-08-25 17:48 -0400
              Re: Thanks guidance mechanical etc. - preoccupied lime mortar'ing Richard Smith <null@void.com> - 2026-09-02 13:20 +0100

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