So I have spent at least 4 hours today contemplating and contacting suppliers of metakaolin, silica fume and flyash, because my belief is that peoples resistance to doing things right often hinges on economics not rationality - I am wholely behind the wish for empowerment at an affordable price - still would we not want to build things to last - perhaps you are correct in that many times it may not matter if you are just trying to put a roof overhead ( 1 am having to do that myself right now with just $10,000.00) I am trying to bring focus , For the group, to the science and technology of all this and not just stick my head in the sand -Clyde
From: "prrr.t21@btinternet.com" <prrr@talk21.com>
To: papercreters@yahoogroups.com
Sent: Tuesday, April 3, 2012 8:39 AM
Subject: [papercreters] Re: Concrete Planet
--- In papercreters@yahoogroups.com, "Clyde T. Curry" <clydetcurry@...> wrote:
>
> Where lime does increase alkalinity , thus killing off organic life , one would think that there is plenty of lime (30% unreacted on set)in the portland itself
there is, until you add pozzolan, which reacts with the lime to form additional hard compounds. By getting rid of the free lime the pH is thus altered from alkaline to nearer neutral.
> - Lime is added to portland at the point of manufacture specificly to control the speed of set - when lime is added to make mortar, it is added to weaken the mortar so as to control differential shrinkage under freeze thaw conditions - While at evesgarden.org I built a dome using mortar mix and paper, it took 3 years to finish original set and then demonstrated radical shrinkage - I think lime is the enemy of papercrete since I have experienced it first hand
I've never experinenced any problem with papercrete using OPC and no pozzolan, so I'm unclear how the lime content in it would be a problem. Have other people found problems when not using a pozzolan?
> - pozzolan is indicated and it is how the industry has dealt with these problems for 30 years - Good Question though - Thank you - Clyde T.
I thought most of us made papercrete ok without it.
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