10" x 5' would weigh excessively when saturated, so it will just be kept damp. But one has to allow for misuse, getting caught in torrential rain etc, so its got to survive saturation.
Re the costs of a hydraulic press & high pressure pipe... the aim is for these to be makeable by people that cant come anywhere near affording a bottle jack or pipe. Hence the choice of scrap paper. A wood stick lever is within that budget, but not a pipe mould. This is why I've been looking at a minimum amount of cement. If this goal is truly unachievable, switching to bottle jack & pressure pipe is possible, but it would be a plus to avoid that.
Plant roots will try to break the stuff up. Somehow it needs to survive that - I'm hoping a plastic wrap will handle that. Whatever's chosen will get tested of course.
I was thinking cement could bypass the upfront cost of equipment problem, if the amount used is small & thus cheap. The papercrete could simply be moulded in the plastic film wrap without pressure.
Initial figures suggest the material cost is similar for weak papercrete with scrap plastic wrap versus pulp with proper stretch wrap. The latter also requires equipment, the cost of which is a) prohobitive for most, and b) would increase product price due to amortisation of the equipment cost.
A small scale sample would be a lot easier to make, but would dry out relatively fast creating a watering issue.
Does paper pulp moulder? If so I'm not sure how to stop that.
I've assumed so far that these poles would only be good for one season. Perhaps they could last longer somehow?
thanks for all the input so far.
--- In papercreters@yahoogroups.com, "JayH" <slurryguy@...> wrote:
>
> Thanks for the additional info. Your goal is much more clear now.
>
> You talk about the need for light weight. I don't see how a 10" diameter 5' high pole will be lightweight when it gets saturated or wicks up hydroponic fluid. The water weight will be far greater than the weight of the paper.
>
> I would encourage you to consider not using cement at all. Just make a paper only slurry, drain it on a screen, and COMPRESS it with as much pressure as you can muster into your pole shape. You'll be surprised how strong highly compressed paper pulp will become.
>
> Just to be clear, I'm not talking about just pushing on the pulp with your hands to squeeze it with a few pounds of pressure. I'm suggesting using something like a 10 ton hydraulic bottle jack. (They are extremely inexpensive. You may already own one.) If you created a form that could withstand that kind of pressure and compressed damp paper pulp with a few tons of pressure, it may be strong enough for your needs.
>
> Almost all of your expense would be in building your high pressure reusable form that will still allow water to drain out of the paper as it gets compressed. I would suggest checking at your local junkyard for steel pipe that is 10" diameter or so, and they trying to build a cap on one end, and a "piston" that can get compressed by a bottle jack into that pipe to squish the paper pulp. The piston need not be a perfect fit, since you'll need to allow water to drain away as the pulp gets compressed.
>
> You should almost be able to turn scrap paper back into logs of wood with such a device.
>
> Of course, without anything added to the paper, those logs will mold easily and have practically zero tensile strength, particularly when damp.
>
> Before investing time and money in the big fancy pipe and piston, I suggest experimenting in a small scale using whatever scraps you have laying around and with whatever jack or other compression device you already have. Then you'll start to get a feel for what compression can really do to damp paper pulp.
>
>
> You may or may not find these thoughts helpful, but perhaps there are some ideas in there that will inspire you to find a solution you like that works for your situation. Feel free to try whatever variations make sense to you.
>
> Please post updates and photos as your project progresses.
>
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Sunday, March 17, 2013
[papercreters] Re: Papercrete as growing medium
