Alternative materials 1: Perlite.

[Little John]

I'll openly admit that the reasons I'm looking at alternative materials is that a) I've just bought some more wood to make a KTBH, and my wallet now hurts, and b) some time ago I inherited several cubic metres of horticultural Perlite which hasn't been touched in well over ten years.

So this afternoon I decided to run some figures, and this is what has resulted:

I'm using Cedar (with 12% moisture) as a reference, which has a density of around 23 lbs/cu.ft.

The density of a cement/perlite mix is:
1:8 22 lbs/cu.ft
1:6 27 lbs/cu.ft

So, they're not outrageously different.


Turning next to Thermal Conductivity (k = W/(m.K))

Cedar has a TC of 0.21, whereas Perlite is a much better insulator at just 0.031 - even when we add-in some Portland Cement (at 0.29) - giving a TC for a 1:6 mix of 0.08, and a 1:8 mix as 0.07

But - back in the real world, I'm guessing that a thickness of at least 3x that of wood would be needed for equivalent strength.
I made-up some test blocks a couple of years ago to see if using Perlite with Cement was a viable proposition, and the end-product turned out to be good, and very light. But I never tested it to destruction - wish I had now. If I should find those test pieces, I'll take a hammer to 'em.

So, the bottom line is that a hive made from a Perlite-Cement mix will have walls 3x the thickness of Cedar, but having 7x it's insulation value.
However, the Perlite-Cement hive will be 3x the weight of a Cedar hive, or 2 to 2.5x the weight of one made from a heavier pine. Hmmm.

The next thing to consider is the logistics of how best to fabricate with this material, but before doing so, I thought I'd ask here first in case someone has ventured down this particular road already ...

 

[sputnam]

There's a bee research group in N Devon which has at least one concrete hive. They say this performs as well as any other.

 

[Tom Bick]

What are you going to do make a mould and cast the hive?

 

[VEG]

Best of luck and hope your back holds up

Another thought is does this stuff contain asbestos if as you said it is very old.

 

[madasafish]

I think the idea of :a super heavy, fragile and easy to break hive sounds quite logical: if you are determined to ruin your spine.

 

[Little John]

Thanks for the feedback/ comments.

What are you going to do make a mould and cast the hive?

That's certainly one possibility - the other would be to cast sized planks, and then epoxy those together. (epoxy being something else I fortunately have in reasonable quantities)

No asbestos - this stuff is expanded volcanic rock - used everyday in modern horticulture - 100% safe.

I think the idea of :a super heavy, fragile and easy to break hive sounds quite logical: if you are determined to ruin your spine.

Well the fragility I'm not entirely convinced of at this stage, but should it prove to be in any way fragile, then I'm fairly confident that could be remedied with a couple of layers of wire netting inserted into the cast.

Spine ? I don't get it - why would I want to lift it ? This would undoubtedly be a material with which to make some form of static horizontal hive.


I'm surprised no-one's enthusiastic about the significant insulation factor - would be ideal I'd have thought in places with harsh winters or very hot summers. And being made of non-organic material, it would be 100% termite-proof.

I can't see it being used for a hive top though - well, unless the top was to be made in several sections. Still a lot more work to be done, so back to the drawing-board ...

 

[REDWOOD]

So your looking for something like our top bar beehives made of concrete and never to be moved, I can see the reason, however you do need a strong pair of legs to stand it on

 

[Alabamaeee]

Concrete boats are made by DIY boat builders, so why not hives. Make the hives difficult to steal, that's for sure

 

[madasafish]

Not only will you need strong supports , you will need to pile the ground to support the weight..

(I am serious: after all the rain in April/May most of my hive legs appear to have sunk 10cms into the ground: I have had to place wooden supports under them..)

 

[user 6228]

Thanks for the feedback/ comments.

...I'm surprised no-one's enthusiastic about the significant insulation factor - would be ideal I'd have thought in places with harsh winters or very hot summers. And being made of non-organic material, it would be 100% termite-proof.

I can't see it being used for a hive top though - well, unless the top was to be made in several sections. Still a lot more work to be done, so back to the drawing-board ...

Use foil coated foam for the roof for lightness and make it at least 2" thick as the shape of a TBH loses twice the heat of a conventional hive.. Cast a concrete base then a hollow plinth out of concrete or block work. The ground pressure should be ok.
Go for a wall and floor thickness that gives at least 10 times the insulation value of the thin wood of a conventional hive. (to match a tree nest with 6" walls)
Make it bottom entrance only.(to match a tree nest). You wont need top ventilation because you will have insulation and large thermal mass and moisture absorption.

 

[talon-ted]

I suggest you look at some additives to help bind the mixture together. I know of three main ones:

Poly fibres are cheap but not that impressive.

Short twisted metal strands are used in mining when lining tunnels and have a good reputation.

Glass fibre strands are probably the best option but you need a special sort that doesn't corrode in the alkaline conditons caused by cement and they were expensive last time I looked circa 10 years ago.

Bst of luck

Mark

 

[DulwichGnome]

Would some sort of wicker basket, made to the right size, and then 'daubed' with your cement/perlite mix hold together? Or mud and Perlite? Or anything else that might be laying around and Perlite! I believe they use to daub skeps to make them water proof in the good old/bad old days.

Just a thought.

Mike.

 

[Finman]

.
What about straw and clay...

[ame]http://www.youtube.com/watch?v=7J0862TFPwU[/ame]

[ame]http://www.youtube.com/watch?v=eMVqJk_SHFY[/ame]

.

 

[Little John]

Some good thoughts there (thanks), especially re: binding the stuff together.

Right- it's time to actually DO something, as theorising is all very well, but ...

As a test, I've decided to cast a 3" thick plank, 22" x 12" - half the length of a 'standard' KTBH side.
That will involve little effort, just some 3" high battens nailed together lying on top of some polythene sheet as a mould.

The reason for the half-length is that I am concerned about the compressive strength of an angled plank over an unsupported 44" length (which of course is being deflected downwards by the weight of the combs), and can see that a central support rib might be required - so I only want to test a length equal to the unsupported section. If it can support a 56lb weight when angled, then I'll be happy.
The other option would be to make a TBH with vertical sides, which would easily support that kind of weight. Hmm.

Well - if nothing else, making a cast will enable me to estimate the all-up weight of a Perlite-Cement hive, which should prove interesting ...

 

[justme]

The z*st hive (*e)is made of something like that but in blocks. Also/ long horizontal hive but with, if I remember correctly a huge depth compared to a normal hive. Those frames are made of bamboo and are 3 storey, just pinned at the the corners, they close up with no comb is in them. Forgotten the chaps name but he has written a book about it and has/is moving all his bees into them. Has a bit of website?page? I think also.

 

[Little John]

Ok - I cast a block on Wednesday midday, and it's now Friday midday(ish) and I've just been outside to check it, and the cement is still 'soft' (not surprising, really), but already this technique is showing itself as having some serious negatives.

Unlike the test blocks I cast previously, this one is showing significant 'cement migration' towards the lower surface - perhaps the mix was too wet ? Maybe the overnight rain (x2 !) has had something to do with it ? But this does show that manufacture using this stuff can be problematic.

I've never had this problem when working with conventional concrete, where presumably the small particle size of sand helps to adsord the cement ? But - can't use sand here, as doing so would add too much weight.

But by far the biggest problem - that I should really have foreseen, but didn't - is the time it will take to make a hive this way.
We're looking at 4 or 5 days at least for the cement to 'cure', and then a week or more (very much weather-dependent) for the slab to dry out thoroughly.
Say a minimum of 2 weeks per slab. So making them individually would take a very long time indeed.
That leaves either casting all the planks simultaneously, or casting the hive in toto in a purpose-made mould. Neither of which seem very appealing right now.

For in contrast, a basic KTBH structure (ends and sides) can easily be made from pallet-wood in just 2 days if everything is set-up beforehand: the first day to recover the wood and glue wide planks together from the thin ones. I use epoxy, so leave overnight to cure, and then cut and fit together on day 2. This leaves plenty of time on both days to make Top Bars, or make a start on the Roof.

So right now it's looking like 'no contest'.

But - I must say that there is something very appealing about using mud (and maybe perlite) and a wicker structure, very much along 'wattle and daub' lines - after all, that's a technique which goes back centuries.

 

[The Cumbrian]

I am afraid it sounds too much like hard work for me. My mate made me a KTBH today Cedar £30 and finished (more or less) 10:00 and 3:30 between.

Only extras are 8 bolts for legs some ply for the roof and a bit of roofing felt (in the absence of anything better).

Seems like good value to me.

 

[Hivemaker.]

But - I must say that there is something very appealing about using mud (and maybe perlite) and a wicker structure, very much along 'wattle and daub' lines - after all, that's a technique which goes back centuries.

Bit like living in caves ect.

 

[Little John]

I am afraid it sounds too much like hard work for me. My mate made me a KTBH today Cedar £30 and finished (more or less) 10:00 and 3:30 between.

Couldn't agree more with you. I've finally given up on this method of construction. Free material, but has turned out to be false economy. And far too slow.

Although it's been a disaster (due to mixing problems, mainly), it's been a useful learning exercise - if only to learn what NOT to do.

 

[Skyhook]

Not sure why everyone assumes horizontal means top-bar. If you have a reason for going horizontal, the Dartington would seem at least as good a design (still probably not as good as vertical though)