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GSBN:Re: Hydraulic Lime



Hi Derek,

thank you for your reflection. I guess hydraulic lime gets involved to speed
up the drying process in wet climates.

The problem with straw is, we need to protect it during the long drying
period when it can't yet protect us.

Strawbale floor Just phoned with Rene Dalmeijer who explained the technique
Werner Schmidt applied in Switzerland:

vertical tubes with airspace in the beton and fleece on them + gravel...

More reflections?

Best wishes, Martin





----- Original Message -----
From: "Derek Roff" derek@...
To: "GSBN" GSBN@...; "Martin Oehlmann"
martin.oehlmann@...; "European Strawbale List"
strawbale@...; echoventures@...
Cc: "Bruce King" bruce@...; "Dirk Scharmer" ds@...
Sent: Thursday, September 23, 2004 6:19 PM
Subject: Re: Hydraulic Lime


> Does hydraulic lime have the vapor permeability of traditional high
calcium
> limes?  My guess would be that it doesn't, but I haven't seen any figures.
> How does the vapor permeability of the St. Astier lime render compare with
> standard lime and portland cement/lime renders?
>
> While it is impressive to claim minimal water penetration in the render
> after the equivalent of four months of continuous rain, what that really
> tells us, is that the material has properties that we don't need.  As
> noted, we never get four months of continuous rain.  Such claims appeal to
> a reflexive "more is always better" enthusiasm, and often disguise the
> negative side effects of excess.  I think it is more important to have
good
> vapor permeability than to have extreme water resistance.  Especially if
> there are concerns about ground moisture entering the structure from under
> the house.
>
> Standard lime renders have adequate resistance to water penetration, even
> in wet British and French climates.  They have excellent vapor
> permeability.  Lime putty can be stored for years.  The increased water
> resistance of hydraulic lime is not needed, so far as I know.  Vapor
> permeability is unknown (by me).  Hydraulic lime cannot be stored after
> mixing with water.  Working time is limited.  In my view, these last two
> factors make hydraulic limes inferior to standard limes for building
> renders, especially for amateur builders.  No doubt there are some
> situations where they would be appropriate.
>
> Derek
>
> --On Thursday, September 23, 2004 3:18 PM +0200 Martin Oehlmann
> martin.oehlmann@... wrote:
>
> > St. Astier NHL2  is composed of 55-60% airlime and the rest hydraulic
> > lime.
>
>
> Derek Roff
> Language Learning Center
> Ortega Hall 129, MSC03-2100
> University of New Mexico
> Albuquerque, NM 87131-0001
> 505/277-7368, fax 505/277-3885
> Internet: derek@...
>