No more than any other reinforcement.
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Sort of bumping this one a bit.
Does anybody have any thoughts about block construction v poured construction?
There was a similar burglary of a money chest here in the states back in the 1870's, where the chest was delaminated in a 2 hour period. I wonder if either burglary could be performed as quickly today using the exact same equipment. Certainly would be interesting to watch, both the now and the then. Being able to make something that is a great improvement over existing technology is one thing. Getting someone to pay for it is another. I remember reading about a vault constructed in Africa. A typical heavy bank vault door, but the vault itself made of sticks and mud. Or maybe it was cow dung.
My father told the story of a strongroom in a factory where the thieves came in through the roof, which was simply the floor of the room above- boards underdrawn with plaster.
I would want to see compelling evidence of such stories as most strongrooms, in my experience, are put in at the stipulation of an insurer, and they specify every one of the 6 surfaces.
Hello again Chubby,
The decision as to block v instu is really a matter for the structural engineer and architect and dependent on the the site situation, access, cost etc.
The customer's requirements are linked to the Risk Assessment and can be adjusted either way by increasing the specification of thickness, compressive strength, additional protection such as the use of fibre or Wirand additives for additional tensile strength.
One major consideration however is water tightness. A pre-cast block construction will never meet this requirement in basement installations. Another is quality control. Pre-cast blocks can be tested more effectively than cast on site concrete where cube tests have to be taken and tested for every mix long after the pour has taken place. Similarly the vibration of the mix for effective penetration of the reinforcement be more efficicienty carried out on individual blocks than in situ.
Here endeth my thoughts.
BTW, Doug, was the mud poured in situ, or preformed into blocks?
So it appears it was likely both mud and cow dung. After extensive research on the subject, the Massai favor a formed block of sorts for their homes. However, I suspect more of an intertwining of sticks to give the structural strength needed when the door is open. Wood has considerable strength when in tension. As to insurance, I doubt that was a consideration. And to think that vault even offered considerable fire protection. When in Rome...
Ah, a barrier material formed of several different materials fastened together. That sounds more of a John Tann design than a Chubb one to me. It was probably a prototype TDR, being "turd and dried rushes".
The enhanced intertwining of sticks was possibly something like this old archive photo, although probably more for in-situ poured vaults and not intended for basic block construction. From an unknown installation marked as "walls prepared for 15-ton anti-lance treasury door".
Attachment 19046
The inclusion of Turdbar reinforcement on some highest grade installations no doubt offered reassuring additional protection.
Sounds classic victorian John Tann, but for a specialised and specific market in today's world they'd possibly consider later generation barriers like Dungcrete III or IV.
I know some people prefer a freestanding strongroom, so it can be observed from all round. That one seems to be ideal from that point of view.
Actually talking of mud walls...... I once put a small SR in a location where the existing walls were adobe. They really were all over the place- corners were not square, walls ran off straight and vertical. So we put the block work in as specified- the blocks with 2 hollow squares in them, and then filled the hollows with a special mix. We had plenty of mix and so suggested filling the void between the adobe and the blockwork. It was anything from almost nothing up to 6" in places. The job was much better for it as the hole would have been a rat run.
Normally I would never pour concrete against an existing wall as the wall would almost inevitably crack, but there is so much give in adobe that this wasn't a problem.
As I sit here musing I just wonder what anybody thinks on existing walls. I was always told never to "use" an existing wall, or floor for that matter, but to build a wall to specification inside the existing. Of course it all depends what the customer orders.