[GSBN] Compression

Sarah Johnston sol_design at yahoo.com
Tue Jun 2 12:53:52 CDT 2015

Hello Andre,

This sounds like a fun project.

Some different techniques we have used.... 

2500kg trucking straps pulling the wall down.  They are ratchet straps and get removed after the wall has been suitably compressed, leaving less substantial straps in place.

For our, 'infill' walls we use hydraulic jacks under the top plate to push the wall down prior to the last bale being placed into the wall.  We generally use a 2000kg jack above each bale.  This technique gets a good tight wall but is a difficult technique if you do not have a top plate that is strong enough or no top plate at all.

Not very accurate but worked well....  using a tractor with a bucket to push the wall down and winching vehicles off the ground....  These techniques were used when a living roof was being installed and the 900kg plastic straps were breaking during compression.  Once the wall is compressed the 900kg straps work fine.  

We look forward to hearing more!

Sven and Sarah Johnston
Sol Design, Ltd.
50A Connolly Street
Geraldine 7930  New Zealand
03 693 7369
sol_design at yahoo.com

On Wed, 3/6/15, André de Bouter <contact at lamaisonenpaille.com> wrote:

 Subject: [GSBN] Compression
 To: "Global Straw Building Network" <gsbn at sustainablesources.com>
 Received: Wednesday, 3 June, 2015, 1:36 AM
     Hello Balers and Balesters,
     The French SB Network is invited to participate in a
 testing program
     on loadbearing SB. We'd like to show that compressed
 unplastered SB
     walls can carry a decent load. Of course we know that
 this has been
     proven before, but hey, this is France, we have to prove
 that the
     same laws of physics and logic apply here as well, so
 that the
     French can accept it is true (you never know, eh? ;-).
     The basic idea is that if we can show that such a wall
     précompressed at, say, twice(?) the load it will carry
 in the
     future, it should be a safe bet that it will hold the
 future loads.
     I cannot yet explaine the details of what and how we
 want to test as
     they are not yet defined. We'd like to test
 unplasterd small, middle
     sized and big bale walls in order to mesure the ratio of
     height relative to dry density of the bales and the
     a few plastered walls might be tested too.
     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
     compression load. 
     I found this pneumatic strapping device :
     but it 'only' goes to 7500N (750kg - 1650 lbs)
     I found straps that go 1170 kg - 2574 lbs
     Comming acros this device I figured that compressing
     walls would finaly become a controled piece of dense
 cake. But I
     wonder if this machine (for a 'mere' 2000€)
 has what it takes to
     compress enough.
     We could also use mesuring devices under the straps,
 (maybe cheaper)
     but probably finiky.
     Have any of you have found the 'perfect',
 controlled, compression
     method yet?
     Any suggestions on how much you would press the walls
 and how big a
     safety margin engineers, building officials and builders
     (our biggest hurdle in France) would consider ok?
     Our starting point is to convince that a SB wall can
 carry 500kg
     (1100 lbs) per meter of wall (about 3 feet). Does a
 compression of
     700kg - 1550 lbs 'impress'? or should the margin
 be much higher?
     André - squeezit - de Bouter
           Maison en Paille
       Organisme de formation
       enregistré sous no. 54 16 00646 16
       Rue des Chaumes, Les Pellières, 16120 ST-SIMEUX
       05 45 66 27 68    
       contact at lamaisonenpaille.com
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