I think it is fine to have this scientific information for the benefit of those new to papercrete who may tend to question its strength and durability. However I also appreciate that one of the greatest attributes of papercrete is that it is simple and can be made by virtually anyone who has the materials (very basic - paper and cement) and a vessel to mix them in.
This seemed to be the general concensus at the papercrete seminar we went to in Tuscon back in Oct. Kent Rabon was there to represent Mason Greenstar, his son's enterprise. He explained that they had spent a lot of time on R & D and on the manufacture of special mixing and pressing equipment, also that they had a secret ingredient which allowed them to successfully patent their product. I think I was the first to comment that this represented the antithesis to our reason for loving papercrete. It takes something simple and easily understood and drags it out of reach of most people who would be inclined toward this sort of DIY activity. I felt sort of bad about starting this because Kent is a really nice guy and then several more attendees sort of jumped all over him, which was not what I anticipated when I made the comment.
What it comes down to is this: there is room for everyone in this creative environment. We can all learn from each other. That's why we are part of this sharing group. I choose to keep things more simple than most. I have my formula that I constantly tweak, but not very much. Kent and Zack and their group are at the other end of the spectrum. It really is a blessing that we have people doing work like that. My dream is to design and consult on papercrete projects. I realize that many who see the great benefits of using papercrete are not in a position to make it themselves and are probably going to build with a permit, which would make the Greenstar product the perfect choice. Mason Greenstar's work on their particular product benefits all of us and helps to push papercrete more toward the mainstream of alternative building materials. It gives us credibility, which is important to promoting the use of papercrete.
They run workshops occasionally. I would love to go sometime and if I do I will personally inspect their blocks to see awhat they look like and how much they weigh. My blocks, made with 1/2 bag or less cement per 200 gallon mixer, come out very strong. I haven't done any formal testing but I have driven over them with my 2500 HD and not made a dent. I think they weigh about 5 lbs for a 1 square foot block about 5" thick.
Sincerely, Judith
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To: papercreters@yahoogroups.com
From: criswells.ok@sbcglobal.net
Date: Fri, 26 Jun 2009 03:04:35 +0000
Subject: [papercreters] Re: Recipe Ratios
--- In papercreters@
Don't their blocks have holes in them? Similar to traditional concrete block or cinder block? That would dramatically change things compared to a typical solid block that most papercreters make.
No the blox he referred to in the file I have posted in the files section clearly is a adobe type block, and when asked how much it weighs he said 8.5 lbs. He does make other blox other than the adobe type that do indeed have holes similar to traditional concrete blocks or cinder blocks, I don't know how much he said those weigh. I think the way he gets the lighter weight is because he pours a slurry into forms there by traping air pockets as the water evaporates.
He goes on to say:
"Generally, as is well know in this art, strength of concrete is normally higher at lower water to cement ratios, but must be obtain with a compromise in materials to achieve a workable matrix for molding. Additionally, it is well know that concrete structures must achieve high compressive strength. Compressive strength is a function of a time dependent hydration reaction which occurs as moisture is added to the non-hydrated cement. Low water to cement ratios increase the compressive strength of the product significantly. Because air entrainment appears to lower the compressive strength of concrete at a given water to cement ratio, its use may seem problematical. However, air entrainment not only makes concrete more durable, especially under severe freeze-thaw conditions, but it also adds to the workability of the material in the molding stage, as measured by the slump test, which is used by artisans in this field to measure workability of the raw product. Workability must not be so great as to cause segregation or bleeding of the concrete. Bleeding is movement of water to the surface of the sample which suggests higher localized water to cement ratios and lower surface strength and durability of the poured material.
The moisture content of the mixed product is also highly important to the strength achieved by the mix. The reduction or removal of the surface moisture slows down or stops the hydration reaction. The interruption of moist curing of freshly poured concrete after a given period of time by exposure to dry air ultimately stops the curing of the poured material. Accordingly, moist cured building materials can exhibit increased compressive strength over those dried too rapidly.
Finally, temperature is another important factor to be controlled in the production of these building materials. As has been long known in this art field (in fact since Roman times), the hydration reaction in cement releases heat, and the rate of hydration is higher at higher temperatures. Therefore, the correct type of cement paste, the water to cement ratio and the treatment to achieve the optimal strength differ according to the ambient temperature. The provision of ovens with moist heating or steam blanketing is expected to more carefully control the time and temperature required for the production of materials made from the invention of the present application, all in manner well known to those in this art. "
--- In papercreters@
I just downloaded Masongreenstar quote from his patent #20090065978
"This building material composition in an uncured state is made up of
between about:
- Between about 70 & 74% weight water
- Between about 7 & 8% by weight shredded paper
- Between about 18 & 20% by weight cement (80% Portland and 20% flyash)
- Between about 0.1 and 0.4% by weight cement conditioning admixtures (a lot of these are liquids)
lets convert these %'s to lbs:
- 74 lbs water (at approx 8 lbs per gallon), that would be about 9.25 gallons, (not a whole lot of water)
- 8 lbs shredded paper (dry weight, not much paper compared to the cement content)
- 20 lbs dry cement (I believe dry portland weighs about 5 lbs per gallon, that would be about 4 gallons, (that is an awful lot, and it would be really a lot if dry cement weighs more than 5 lbs per gallon)
- 4 lbs other conditioning admixtures (way to much information listed here for me to understand, and also too much added cost as well, I would just stay with something simple like clay or sand.
I can't see where his 10 inch by 14 inch by 4 inch blocks could only weigh 8.5 lbs. I don't know for sure but I believe the above mixture would fit into my 9.5"hx12"wx16"
that 32 lb figure by adding the 8lbs paper, 20 lbs cement and 4 lbs other. What are your thoughts on this? (after re-thinking this the four lbs are mostly liquid and would press out with the water so if that is so, the weight would be about 28 lbs, same as my second batch)
In my other post where I was referring to 2 gallons of slightly wet paper pulp, I will have to weight the dry paper that got pulped to see excatly how much dry weight I was referring to. I did not weigh the dry paper first I only dipped it out of the pulping container (draining it through my fingers) and dropped it into a gallon container twice, and then into my mixing bucket.
Thanks for the info.
Bob
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