Re: Aquatic Plants Digest V2 #33

> From: PacNeil at aol_com
> Date: Thu, 25 Apr 1996 10:38:36 -0400
> Subject: Palludarium
>  --charley cbay at jeppesen_com, cbay at verinet_com wrote:
> >For technique (more in line with your question), I know the irregular
> >rock faces on many houses start with side board, which they nail
> >chicken-wire on top of, then build a cement rock wall in front of that
> >with the cement grabbing hold of the wire for additional support.
> >I'm going to look into tile supply houses and see about doing a similar
> >thing with rock, grout, and tile adhesive (I don't want to go with
> >the plastic back-drop either).  While my sides will probably be glass
> >(greater viewing area), the back might be that "concrete wall-board"
> >used for tiled areas (totally impervious to moisture, I'm told).
> If kept continuously wet, I would expect lime to leach out of the "builder
> board" causing the alkalinity to rise in the water. Eventually the cement
> will turn to sand. There is a product sold in our area called "water lock" or

  If concrete did, in fact, eventually turn to sand when subjected to
water, a lot of people living downstream from a man-made dam would be in a
world of trouble.  During the setting process which turns cement into
concrete, the water is hydrated onto the cement particles, causing crystal
formation.  These interlocking crystals result in a matrix of significant
strength.  It is also stable under exposure to water subsequent to
setting.  The question of whether concrete is inert in water, without
additional treatment, is not in my field, however.  Concrete is often used
to build municipal water storage facilities, so it is possible to get
concrete with this properties.