Re: [papercreters] Ceiling panels

The things in pc become loose because pc shrinks some as it drys and cures. This shrinkage is in all directions, including away from any embedded objects. I'm sure anyone who has made pc with something solid in it has experienced this. The next time you try a mix, put some in a mold and stick a bottle or something in it. When it cures you'll find the bottle rattling around in an over sized hole.

I have not tried compressing pc around embedded things, and while I think the problem would still be there, someone who has actually tried it would have to tell us for sure.

A 2" thick 2'x4' pc panel should not need additional reinforcing when used as a lay-in ceiling tile. If you plan to pile things on top of your ceiling, that's another story. The shattered bamboo would likely perform like rebar. I know Mikey Sklar embedded sticks and limbs in some 4" thick panels he was making for a fence. If he's still reading this list, maybe he'll comment on his experiences.

Spaceman



Robert Deutsch wrote:

Hi Spaceman and space creter people,

 

Sorry didn’t see ur reply till now.  Thanks for the thoughts on PC ceiling panels.  Why do you think the things embedded in PC become loose?  Have other people had this experience too?

 

Would shattered bamboo make good reinforcing for lager PC panels?

 

Robert (planning for Phnom Penh Project, see below)

 

From: papercreters@yahoogroups.com [mailto:papercreters@yahoogroups.com] On Behalf Of Spaceman
Sent: Monday, June 08, 2009 6:54 PM
To: papercreters@yahoogroups.com
Subject: Re: [papercreters] Ceiling panels

 

Well, just thinking out loud here...

Everything I've ever tried to embed in papercrete ends up rattling around in a hole, except the bamboo that I threw into my mixer and dumped into a slip form. I never saw that bamboo again so I suppose it is doing its duty and reinforcing the pc.

Pouring pc onto a bamboo mat should give you a really nice surface. Papercrete is good at taking a detailed surface from a mold.

Throw in some lime and get a whiter end product for more light reflection.

No need for much portland cement since you don't need strength. Commercial lay-in panels aren't very strong and I think pc would make a great substitute. Just be sure to include a fire retardant like borax or boric acid.

At 1.5" you should get between R3 and R5 depending on your mix and compression. That will do a lot to keep the attic heat in control, and adding some vents if you don't have them would help. 2x4 x 1.5" is a cubic foot, so each pc panel would weigh around ten pounds if light in portland, a bit more than the commercial panels. A good solid structure should support this.

If you don't have a spray washer, borrow or rent one and pulp a couple of 5 gallon buckets to try it out. 1x2 lumber for the mold might set you back $10 if you haven't had an election recently, in which case it is free by the road. Try one with just paper and some borax (20 Mule Team from the grocery store, maybe a half pound) to see, then try one with a couple of pounds of portland cement added. Try to burn them after a couple of weeks, put them between two chairs and pile on weights until they break.

Stacking the molds would compress the bottom ones, but they would take a very long time to dry.

SG did some testing and says his results indicate that compression increases the R value. That is counterintuitive and I have not done any testing along those lines, so I can only pass on his results. I don't think he is making it up. I also don't know if he tested for final density after compression, if there is a trade off between R value and weight.

Never tried steam curing, no opinion. Let us know how it turns out.

Spaceman

Robert Deutsch wrote:

Hi Creters,

 

Long time lurker here…. I have been thinking to try ceiling panels from PC  for an office drop ceiling (the kind suspended from the roof by wires).  We plan to make molds about 2 ft X 4 ft and about 1.5 inches thick. We were thinking  to get a roll of woven split bamboo, cut it into pieces and place it in the mold for the lower (interior) surface and pour the PC on top with some bamboo ribs of some sort placed at intervals for strength (either small round bamboo or split bamboo staves).  We are hoping to get a nice clean, flat surface and some insulation from the attic heat.

 

This is all just theory for the moment, we haven’t tried anything yet….   Few questions for the group:

 

1.       Any suggestions for mixes for thinnish panels?

 

2.       Will shrinkage or cracking be an issue?

 

3.       Are the bamboo ribs or staves necessary?  Are they problematic for cracking?

 

4.       Is weighting or compacting the mix necessary or desirable?

 

5.       Can we make em in layers, sort of stacking the molds like pancakes?

 

6.       Is there any advantage to steam curing PC (I have a friend there with a steam box for curing concrete sewer pipes)?

 

This project is in Phnom Penh, Cambodia for a nonprofit group that promotes recycling, so there is a nice tie-in with their work.

 

Very best regards, Robert

(In California for the moment)

 
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