Re: How catastrophic is catastrophic?

[EdwMullin@aol.com]

In a message dated 3/15/99 8:55:55 AM Eastern Standard Time, protek@shreve.net
writes:

> I know that its coeficient of
>  thermal expansion is different from metals and if joined to metals at
>  places like window seats the two must be engineered to slide against each
>  other as the temperature changes.  It is a far more brittle material than
>  steel in general. 


Hi, 

FerroCement, is extremly flexibly with out crakcking, a 1 in(2.5cm) thick
plank 3ft (~1meter) long will flex and return to shape, without cracking until
the displacement goes past about 1/3rd its length. Generally, Ferro cement
uses very fine aggregate, and a wire mesh.  Not Rebar or thick rods. Infact
the thickest rod would be a mild steel rod about 3/8's inch (~7MM)  diam. 
Ferro cement is actually mortar, the same as used to hold bricks.

As for Temperature, the cement and galvanized steel mesh (which happens to be
chicken wire in a lot of cases!!) tend to remain together ie: they really have
a similar expansion. Remeber, this concrete uses sand, not gravel this would
change the expansion. The biggest problem would be that the builder uses a
very wet mix which causes shrinkage and then there are cracks.  
 
I will look up some of the data and post if you like?  

Just as a side note, this is really great, a lot of discussion and ideas
flying back and forth!!  
The open Forum at its best!!  
Glad I got  on the list!