I realize all you mentioned in your post. If I were to use this 2:1 cement to paper ratio in my current mix, I would be putting 120# of cement with 60# of paper or 1.27 bags of cement for every 9 bricks. This seems excessive at first glance but then maybe not.
These 9 bricks I get out of a 60# of paper batch are 8"X8"X22" so each one has 1408 cubic inches of volume. I can't find cement any cheaper than $11.85 a bag (and to get that I drive 170 miles). So at 1.27 bags per batch that would run $15.00. In order to do a good comparison on a house, this needs to be converted to cost/cubic inch because no one would build a house with this size brick (I'm only making a storage shed for a 3 wheeler with these). So $15/1408 is $.001183 per cubic inch. On a house brick (I plan on 6"X12"X16") there would be 1152 cubic inches, which, when multiplied by the per cubic inch cost would make each brick cost $1.36.
Assuming a 3000 square foot house (50'X60") there would be 220' (linear) to a round. Assuming an 8' eave, there would need to be 16 rounds of 6" deep (my hypothetical brick's vertical size). So to determine the number of bricks per round the 220' is converted to 2,640 inches and divided by the length of one brick (16"). To make one round 6" deep (excluding door and window stuff here) would take 165 bricks. Multiply that by 16 rounds to get to the eave and you have about 2,640 brick total.
If this is accurate then the walls (exterior only) could be made just under $3600.00 for a square footage cost of $1.20. The safety factor would outweigh any other consideration even for those without a family (what, no one ever visits?) Skimping on cement is not recommended!
Someone should check my math, but this really is economical. Of course, it is sans roof, windows, doors, plumbing, and electrical, but this is a substantial portion of the structure. I haven't built a house recently so I can't say what the per square footage is, but before the economic downturn here, they were saying $160 per square foot.
I sensed a nervous call to action on your part, and to make sure the group's point came through well, and it does. Even though I have been puttering about with this for the third summer, I consider myself still experimenting and learning. Many of the responses from the moderators on these posts are to: "try it and see how it works". Well, that's where I am. I am not building a house (yet) and actually am just slowly collecting paper to that eventual end.
Thank you your point is well taken.
Ron
From: slurryguy <slurryguy@yahoo.com>
To: papercreters@yahoogroups.com
Sent: Monday, July 13, 2009 2:09:19 PM
Subject: [papercreters] Low cement mix ratios and fire -was-Don's nice new photos
Ron:
One of the biggest reasons many people use more cement is to get their finished cured/dry papercrete to be non-smoldering.
A 30% cement/ 70% paper papercrete mix, (by dry weight), with no other additives, will very likely continue to smolder if exposed to fire. It can gradually smolder like a hot coal for hours and hours and eventually all the papercrete will be consumed. Put a torch to a small sample of COMPLETELY DRY low or no cement content papercrete sometime and watch what happens. You simply cannot blow them out if they catch fire. They will actually get hotter with the wind. You must either completely drench the papercrete with water, or physically chop out all of the hot coals from the sample, if you want to avoid the water damage. Some chemical fire extenguishers can often be particularly ineffective.
The most dangerous aspect of this kind of fire is that it can hide and slowly eat away at a structure without anyone being aware. It may take days or weeks depending upon the size, how the structure is built, and how the papercrete is covered.
The more mineral content you add to a papercrete mix, especially finely ground mineral content, the less flamable and smolderable it becomes.
Also... higher percentage cement mixes are typically stronger than lower percentage cement mixes.
The exact non-smolder ratio point, cement/paper, for papercrete is somewhat inexact. Different paper sources have different amounts of internal mineral content. Some mineral content comes from inks, some papers have minerals already embedded in them. Glossy and color papers, like from magazines or those fancy colorful newspaper advertising inserts have some of the highest mineral contents in them.
As a general rule of thumb, a 2-1 weight ratio of dry cement to dry plain newsprint should be non-flamable and non-smoldering with plenty of margin for safety. Someone can often go a little leaner on the cement, but 2-1 is a good starting reference point for experimentation with plain simple newsprint that should not sustain any fire or smoldering.
It's easy to reduce the amount of cement required to get the same results by substituting fine clay or other mineral fines for some of the cement. Flyash also works well.
Another technique is to add Borax to the mix. It's an excellent fire retardant.
Ron, if you are using only 30% cement by weight in your mix, compared to paper, the only way that your dry papercrete won't burn or at least smolder once exposed to flame is if it has something else in the mix, whether you put it in there intentionally or it found its way in your mix hidden inside one of your ingredients.
I always recommend that people flame test a sample of their preferred papercrete mix. I always recommend that builders use a mix that won't burn or smolder. It's just too easy and inexpensive to get that good level of fire safety. It's a shame to allow even small risk of health/safety/ property damage just to save a very few pennies when all the different easy inexpensive options are considered.
Food for thought.
--- In papercreters@ yahoogroups. com, Ron Richter <ronerichter@ ...> wrote:
>
> Don,
> I agree about the card board. Seems as though it is everywhere, and as newspapers start shutting down it is good to concentrate on a source that will stay strong. I mentioned on a previous post that I went to the nearest paper printer (Missoula) and they had roll ends (left over from the printing process). These varied in length and diameter. I drove up there because they said they had a lot, but when I got there they only had about 25 AND they wanted .25 for each one. Well for the $7.25 I gave they barely covered 1/2 the bed of my Ford Ranger.
>
> Since you are having good blocks turn out can you share with us the %'s you are using of ingredients? No sense re-inventing the wheel. (water, paper (cardboard), cement, other).
>
> I was shocked the other day when I watched the towmixer on Youtube someone recently shared and the guy said 60 # of paper and 90# of cement. I am just finishing a shed (not a house of course) and have used the 60# of paper but I only use 30# of cement and the blocks are fine. Take a long time to dry however as we get down to 40 at night frequently and we have yet to have a 90 degree day during the daytime (I live in Alaska 9 months of the year so I am definitely not complaining) .
>
> Thanks for sharing!
> Ron
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