"Tony Strong" wrote in message
...

BigWallop wrote in message
. uk...

snipped
http://www.hebdenhey.org.uk/wallsection.gif -
this shows the foundation and the interlocking blocks to be dry-stacked,
the wall will be back-filled with clean 20mm gravel
The reason we need the heights of the step is to ensure
the wall slopes back at a slope of 20 degrees.


To obtain the higher section of the pour, you'd need to seal the top of the
lower section to hold the mix at that level. Even concrete finds its own
level, and this is usually the highest point, of course. So, to make the
difference in height will mean building a sealed box with the height change
section built on top of it.

Saying that, the log pour will need more of a base width to hold back the
outward pushing force of the stacked blocks on top of it at the angle you
want to obtain. So the plan of a straight sided foundation isn't the way
I'd personally go with this. I'd tend to look at building a sloped log with
a wider base than the top to obtain the right balance of holding forces
against the build of the blocks. Like the sloping side of a pyramid,
especially on the outward side of the log.

Would it be possible to drop the first row of blocks into the wet pour? If
the blocks themselves could be held at their ends on the sides of the
shuttering, then the pour pumped around and below them, then surely the
first row of blocks would be at the angle you'd need, and they'd be
supported along their full length rather than just at the two points of
contact shown by your diagram.

The shuttering could then be made to taper in from a wider base to a
narrower top where the blocks lie, and thus achieve the correct weight of
balanced force against the rest of the blocks when they are placed. It
would also mean just building two walls of shuttering, only having one side
higher than the other to achieve the angle you need for the blocks.

Leaving one block out ever X metres would allow the mix to be pumped in.
Then place the missing blocks in when the pour has been done. If yaw's sees
what a mean.