Monday, April 28, 2008

Re: [papercreters] fly ash versus blast furnace slag

Hi, this is Clyde from www.evesgarden.org - hope I can help - You are absolutely correct ,in my opinion, to be worried about mold etc.- So here is the deal- the portland cement that is generally used in papercrete , if you use the correct amount, goes a long ways to eradicate the possibility o f mold, or anything else, growing within the substrate- ie it is very alkaline -however you can be sure that mold will grow on the outside of papercrete, or perhaps stainless steel- acrylic will, without a doubt , do a good job of occluding water, yet it will pass water vapor, as it is a fairly open molecular structure -it is not advisable to let water accumulate as the paper fiber will wick the moisture unto its own-airflow in a structure has been an issue in buildings ever since we started tightening building envelopes in the seventies  - the necessary flow is twice what everyone allows - this pretty much dictates the use of an air to air heat exchanger, unless you are using natural ventilation ( which is preferable)- still here is the key - in papercrete it is the un-reacted lime (calcium carbonate) that holds all the excess moisture - the cure is pozzolanic additive to react the lime- we use Power Pozz from applied cement technologies at at least 10% replacement of the portland to create a super cement that will not hold water ( we have proven it in our testing) the problem is that people are resistant to spend the money to make these mixes do what we need them to do - I am available (by e-mail) to help with this - sometimes I am slow at answering, still I am here -Clyde
----- Original Message -----
Sent: Monday, April 28, 2008 7:16 AM
Subject: [papercreters] fly ash versus blast furnace slag

I found this article written for the Cement Association of Canada on the web as I was sourcing the base ingredients for papercrete here in Ontario.

http://www.cement.ca/cement.nsf/ep/10BE46299E1FBEB985256E700076EAEA?opendocument

As a hobby potter, I've worked with porcelain clay bodies mixed with paper that impart greater workability to the material and have since been interested in paper and other fibres as structural elements.

Since learning about clay I have always been suspect of the role played by each ingredient and its actual chemical makeup.

Papercrete appears to be a wonderful and environmentally conscious material, but the seriousness of its use in home construction even as it can only be used as an infill product really demands standardization and testing.

Load bearing capabilities would make papercrete an exceptional product where it is merely stupendous.

I have one final concern; mold. In Canada the R2000 standards dictate mechanical heat exchange from within a sealed envelope utilizing plastic vapor barrier to shield from the outside environment. The standard has served well for the past 25 years, but problems along the way included moisture at window junctions and behind the vapor barrier. There have been homes ripped apart to get at the molds growing on paper and wood substrates and even a few deaths from respiratory ailments attributed to this mold.

How will papercrete fare in this regard?




-- tim

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at 9:53 PM