Wednesday, July 15, 2009

[papercreters] Re: New Scientific Paper

I live and work in Indonesia and a close colleage also working here is from India. There is, to some extent, less of the "throw away" behaviour embedded into the cultures of these poorer countries. Indeed there are the "constantly burning landfills" - but overall there is less waste in poor countries where a large portion of the people are scrounging to survive. And in these poor countries there is still a very large element of the "traditional markets" that do not require all the processing and packaging.

For some years now (nearly 10), waste paper (and plastic materials) has been on the list of scrap dealers. My Indian colleage says the situation in many parts of India is similar to Indonesia.

The biggest waste in most of these poor countries is plastic bags that replaced wrappings of not so long ago like banana leaves and other natural materials. Paper is not the largest problem of the trash - but this plastic is.

The higher ambient temps and humidity mandate a labrinth of trial and error adjustments to possible papercrete mixtures that are suitable - and this New Scientific Paper has shed more light on that than anything else I have seen so far.

BTW - to my knowledge - doesn't Florida and some states like it have high temps and humidity?

Cheers, Dave


--- In papercreters@yahoogroups.com, "canineaficionado" <canineaficionado@...> wrote:
>
> Even though I'm not a techie or an engineer type, I slogged through the bulk of the paper by the Danish grad student that Allan provided a link for, before my eyes glazed over. There is some very interesting stuff in there.
>
>
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> http://restart.nu/wordpress/wp-content/uploads/2009/05/bricks.pdf
>
>
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> Some of it is clearly not relevant for most us in the US because of the high percentage of sand/rock aggregate, and the low percentage of paper fiber. This makes for a more dense, less insulating block. This type of block works well for the climate it was designed for (central India, no heating degree days), but I think is less appropriate for heating climates.
>
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> There was an illuminating section on the chemistry and resulting physical linking of cement in the matrix, regardless of aggregate type. (Around p. 35) I did not realize the great importance of having water in close contact for full reaction rates and maximum strength. That is another good reason for a bit of compression of the slurry. Apparently, 33% rate of compression was the magic number for maximum saturation between fibers- the point at which free water ran out of the mix. Neither vibration nor "stamping" (banging against a hard surface) convinced the fibers to come closer to each other like hand compression did. Rats- I was hoping to get away with not doing that step. To the untrained eye, a setup like Clair's seems very complex. It does seem to produce a great product, though.
>
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> They calculated about 45 days for drying before assembling- this is at about 85% relative humidity.
>
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> The conclusion was that the traditional mud brick was still the best for the area because:
> 1. It was an established method with many years of demonstrated use.
> 2. Many people were skilled and available to build with mud brick.
> 3. It utilized mostly local materials.
> 4. The low insulating factor allowed heat to move more rapidly through the walls and out of the house.
> 5. Recycling is not well established yet- paper goes into outlying, constantly burning landfills.
> 6. There is no drying time for the cement stabilized mud bricks.
>
>
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> Here again is an example of climate appropriate evaluation. Papercrete is great for many things, but not in that high heat, high humidity location where another established material is preferable, and paper is not easily procurable.
>
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> Personally, I can't wait to dance it up at the First Papercrete Gathering at Judith's! I'm so glad that papercrete is a really good material in my climate.
> Tina in Colorado
>


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