[papercreters] Re: Vault building--free PDF for construction

Coincidentally, I was researching arches and vaults as a potential papercrete project before I thought to search this forum to see if someone had already given it a try. Next time I'll start my research here first :-)

I'm neither an engineer nor architect but my first impression is that the lighter weight of the papercrete blocks shouldn't adversely affect the properties of the arch or dome. In fact, in their large domes, the Romans used progressively lighter and thinner materials in the tops to lessen the weight on the lower parts of the structures.

But in the absence of mortar or some other retention, could a strong wind "lift" parts of a lightweight papercrete vault? That's a good question. Airfoils and arches have a lot of similarities.

The questions I was going to post here before I found this thread is whether or not anyone has attempted a parabolic or catenary arch / vault with papercrete or paracrete? If so, has anyone attempted to use a slip form method of construction?

My research indicates these forms of arches are self-supporting and don't (shouldn't) require additional structures to contain the outward thrust. (Although I agree a small scale project should be attempted first.)

Using Sketchup and a free plug-in called Curve Maker, I'm able to draw parabolas and catenaries.

Being also fond of lath and ferrocrete, one design concept I'm working on in Sketchup is forming the vault with ferrocrete lath first, then attaching a slip form to the exterior and slip forming up from the lowest ends to the apex with a papercrete layer.

The end result should be a very strong ferrocrete vault with a second, well insulated papercrete vault exterior. If desired or required, a suitable shingle could be attached to the exterior surface to keep the rain off the papercrete.

A variation would use two parallel layers of arched lath about 8" apart (connected by thermally non-conductive spacers) then fill the gap with papercrete. In this version, ferrocrete might be used as the outer shell with plain lath on the inner layer to keep the papercrete dry while still allowing it to breathe. A papercrete mix could then be sprayed over the inner lath for aesthetics.

Both methods appear workable within Sketchup, but again, one can violate a lot of physical laws within Sketchup.

Another question I had for those more knowledgeable on building codes is whether or not a vault that used a load-bearing ferrocrete frame might get approved in jurisdictions where a pure papercrete structure wouldn't (yet).

Any thoughts?

Thanks!




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