[Strawbale] Carbide Lime

[Alan Mason]

Well, if you are talking a true stucco, then here's what the Portland Cement
Association has to say (http://www.cement.org/stucco/faq_coats.asp)

"Proportions are clearly spelled out in ASTM C 926, Standard Specification
for Application of Portland Cement-Based Plaster. [www.astm.org] Scratch
coats are mixed at 1 part cement to 2-1/4 to 4 parts sand, brown coats are
mixed at 1 part cement to 3 to 5 parts sand, and finish coats are 1 part
cement to 1-1/2 to 3 parts sand."

They go on to say,
"It is important to note that the term "cement" includes all cementitious
materials, such as cement plus lime. So if 1 part cement is used with
one-half part lime, that equals 1-1/2 parts cementitious materials, and that
total is then multiplied by the sand number. For the finish coat, for
instance, the range is 1-1/2 to 3 parts sand: 1-1/2 times 1-1/2 is 2-1/4 and
1-1/2 times 3 is 4-1/2. So if we have 1-1/2 total parts of cementitious
materials, the sand parts would range from 2-1/4 to 4-1/2."

A mix I have used frequently is one part portland and one part lime to the
appropriate number of parts of sand, depending on the coat you are doing.

Part of what the lime does, in addition to helping the mix breathe, is
extend the time the stucco is workable. Its called a plasticizer. AVOID
using so-called plastic cements. They tend to cure very quickly and are not
as easy to work with as plain old portland, especially if you are using a
Tirolessa, and you don't want to add any lime to them.

The PCA puts out a short (72 page) and somewhat pricey ($25) book called the
Plaster/Stucco Manual that will give you a lot of the basics of conventional
stucco. You can order it, and obtain a lot of other conventional stucco info
at their website www.cement.org.

If you want to learn more about true lime plasters than you might even want
to know, for about the same price as the Plaster/Stucco Manual you can get
"Building with Lime, A Practical Introduction" by Holmes & Wingate at
Amazon.com. At 300 plus pages, the "Introduction" in the title is an
understatement at the least.

BTW, you weren't planning on using that hay for actual construction, were
you?

@


----- Original Message ----- 
From: "Stone Tool" <owly at ttc-cmc.net>
To: <strawbale at listserv.repp.org>
Sent: Monday, April 23, 2007 4:03 PM
Subject: [Strawbale] Carbide Lime


> I have finally gotten around to inquiring about the huge pile of
> carbide lime available locally...... about 100 miles from home.  As I
> had expected it is free for the hauling...... but I have to load it
> myself.      I probably will go down and load a drum or two to
> experiment with in making my own stucco mix....... I have a truck load
> of bales...... bought a two ton truck the other day for the 18' van
> body, power lift gate, and brand new 20" rubber on an auction......
> stole might be a better word as I got it for a mere $1000.00 ........
> and it had several tons of bales in it as I discovered after the
> auction...... Doesn't run but who cares??   The bales are actually
> crested wheat grass hay..... which is what I probably would have used
> anyway rather than actual straw.
>
> Anybody have any estimates of quantity of lime required per cubic foot
> or cubic yard for stucco...... I am assuming that a 20% cement / 80%
> lime based  mix would be about right.   It'd like to work up an
> approximate quantity for my wall footage so I can accumulate what I need.
>
> My other concern is what chemical state this lime is actually in......
> I can get it pretty fresh from the acetylene plant, or get it many years
> old... any ideas on this?   No doubt some of it would have reacted to
> CO2 in the atmosphere to form calcium carbonate again, though it should
> be pretty well hydrated having come out of an acetylene plant where
> calcium carbide is reacted with water to create calcium hydrate and
> acetylene......... I must admit to being eager to see what actually
> transpires when I mix up lime, sand, water, and a bit of Portland.
>
> Any thoughts or first hand experience???
>
>
>                           H.W.
>
>
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