On Mon, 13 Feb 2006 16:33:01 -0000 TheScullster wrote :
Does anyone have allowable compressive stress values for bricks and
blocks used in 1970s construction please?
The blocks I have heard described as slag blocks - a bit like aero in
construction, but with black bits and solid chunks here and there.
Bit nasty to drill, but more solid/heavy that the modern thermalite
jobbies.

Sounds like breeze blocks. I would treat them as 2.8N/mm2 blocks (this
is the crushing strength: the actual stress you can put on them is a
lot less than this)

The bricks I have heard described as Fletton (sp). Not sure if this
is the correct name, but these are bog standard 1970 house bricks.

Fletton near Peterborough was the place where the clay used to make
them was first found. It contains shale that burns during the firing
process thus reducing the amount of fuel required significantly (and
this making the bricks cheaper). On spec housing they are generally
laid frog down (to save mortar) so should be treated as 7N. Laid frog
up the full 21N crushing strength can be assumed.

Lots about Fletton bricks in a (PDF) Competition Commission report at
http://www.competition-commission.or...ext/088c05.pdf

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