Cracks in new concrete pond.

Concrete cracks due to drying out, or due to other stresses like settlement,
thermal expansion and contraction, over loads, and numerous chemical attacks
that occur years down the road. I suspect the cracks that you are seeing
are caused by the concrete drying out before it has the strength to resist
cracking. Curing is the word used in concrete language for keeping the
concrete moist and the temperature favorable for the hydration reaction to
occur. The cement in the concrete reacts with water chemically to develop
strength, water tightness, chemical resistance, abrasion resistance,
hardness, etc. The longer the reaction goes on the better the concrete is.
If the concrete is allowed to dry out, then the reaction will slow to a stop
and never really get going again. Find a way to cover the concrete with wet
towels, burlap, or similar material, cover with plastic sheeting and rewet
the cloth at least daily to prevent it from drying. Cure for a minimum of 7
days, though 30 days is much better, but not always feasible.

You didn't describe where the concrete is in your system. If it is in the
stream, the cracks could be a big problem allowing water to leak out of the
streambed and into the underlying soil, which could cause the soil to
settle, making the cracks worse. If it is over or under the liner to
support the pond edge, and the water does not go higher than the liner, then
no problem. If it down in the pond, with a liner under the concrete, then
the cracks may self heal.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


"Robert" wrote in message
om...
I have just hired someone to install a pond/waterfall feature. They
used a liner (unsure of thickness) and the concrete was poured
yesterday (it looks like a min. of 3" thick), reinforced with chicken
wire. I noticed this morning that 3-4 (or more)cracks have formed.
Should I be concerned about these cracks? I know that concrete cracks,
but I am a little concerned that the cracks appeared so soon.