[GSBN] Compression (Digest, Vol 50, Issue 1)

RT ArchiLogic at yahoo.ca
Tue Jun 2 18:41:04 CDT 2015

On Tue, 02 Jun 2015,  André de Bouter <contact at lamaisonenpaille.com> écrit

> I'm looking for is a cheap, secure and rapid way to compress the SB
> walls 'a whole lot', that can, preferably, be reproduced on building
> sites. And if possible in a way that one can predifine the compression
> load.

Cher Squeezit de Bouter;

When a massive concrete bridge deck has collapsed and emergency personnel   
want an easy, safe and economical means to jack it up in order to rescue  
people trapped underneath, an "air jack" made by simply gluing up a piece  
of EPDM sheet to make a pillow that can be slid into a narrow space as  
little as a mere centimetre (before inflation) and then inflated, works  
very well.

Some simple arithmetic demonstrates how effective this method can be:

I typically inflate the tires in my "dog bike" (an MTB-style) to about 40  
pounds per square inch (psi) (~ 275 kiloPascals (kPa), which is less than  
half the pressure of that typically used for road bike tires and easy to  
do with even the crappiest of manual tire pumps.

Looking at a 2-string bale wall (bales laid flat), a nominal 18 inches  
wide (0.45 metres),

40 psi x 18 inches (width) x 12 inches (length) =  8540 pounds of pressure  
applied per lineal foot of wall.

That is to say, if one used a tube inflated to 40 psi to apply pressure to  
the top of a bale wall, you would be applying 8540 lbs pressure to each   
one foot length of wall (~ 125 kN/m).
I'll let you figure out how many straps or steel roads and at what  
frequency you'd have to use to achieve the same (if in fact you could do  
it all with those devices in any reasonable fashion).

Pretty easy to show whomever needs to see, what the applied stress is,  
when using an inflated bag or tube -- you just put a tire pressure gauge  
on the valve.

Years ago (in the 1990s ?) Bob Platts utilised this principle to make a  
system for pre-compressing bale walls as part of a CMHC (Canada Mortgage  
and Housing Corp) research project  I know that listmembers Habib Gonzales  
and John Glassford have owned/used that proprietary product/system and  
perhaps can offer some insights on how it could be improved or made  

Bon chance, eh (?),  mon ami.
=== * ===
Rob "Stronzo di Nord" Tom ADT1
Kanata, Ontario, Canada

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