[Greenbuilding] concrete vs block vs ___foundation wall

[Speireag Alden]

Sgrìobh Bruce Donelson:

>A dry stacked wall might be a tad stronger than a wall with mortar joints.

     Two or more times stronger, depending on which direction you're 
pushing in.  At least, so I've read.

>You can kick either of them over.

     This has not been my experience.  Once I have surface-bond cement 
on both sides of a wall, it's there until the earth moves or someone 
spends a lot of time with a sledgehammer.

     Of course, I fill the end cavities with rebar and concrete, which helps.

>All the strength in a block wall comes from vertical and horizontal 
>rebar surrounded by concrete.

     Only if that's how you build them.  And even then, some of the 
strength comes from the compression on the portion of the blocks away 
from where you're applying the force.

>Not every cinderblock is made to exact tolerances. A dry-stack wall 
>offers no ability to straighten out a wall as you go, which is 
>fairly easy if you tap a block down into a mortar bed.

     Not as you go, no.  But you can easily cast a bond-beam at the 
top, or run across the top with a layer or two of surface-bond 
cement, and get things level.

>IMHO the best use of that technique would be for block walls that don't
>require accuracy, particularly if they would be stuccoed. They would still
>require grout for strength,

     Do you mean grout between the blocks, or a poured column?  If the 
former, then no, they don't.  Really.  Quite strong without it.

Sgrìobh Rob Tom:

>Actually, for a surface-bonded, dry-stacked block wall, you really 
>should be using precision-ground block rather than your 
>run-of-the-mill CMU.

     I'm sure you get a stronger wall that way, but all the 
dry-stacked walls I've done have been with regular block.

>Furthermore, come the end of the block wall's useful service life, 
>deconstructing a surface-bonded block wall and salvaging the block 
>for re-use would be relatively easy,

     I have no idea how you would do this.  When I break open an old 
dry-stack wall with a sledgehammer, I get a lot of breakage.  Are you 
thinking of scoring along the joints with a saw, or something 
similar?  Then you might be able to take it apart without too much 
breakage...

-Speireag.

-- 
Leaves starting to turn
Anticipation shivers
Me as winter comes

-Speireag.