On Sun, 13 Nov 2011 23:20:31 -0500 Dave <e...@dc9.tzo.com> wrote: > Concrete is fine for compression loads. You can mix 5000 psi > concrete pretty easily. However it has very poor tensile strength. > They say 10-15% of the compressive strength. Fiberglass has a much > higher tensile strength. > That is why concrete has to be pre-stressed to be used for tensile > applications. > (massive snip>
Well stated! Speaking of prestressed; it is strong simply because of the steel in it; usually cables held at a given tension while the concrete cures. IIRC concrete for prestress goes about 7Ksi in compression after a 30 day cure. That was 50 years ago when I had a summer job in a testing lab. It is my understanding that SiC dust is used in very high strength concrete to increase strength. ftp://ftp.wsdot.wa.gov/dotshare/eforms/update/350_040.PDF The above has some interesting information on mix design and testing. Hmmm! 20 Ksi concrete sounds like interesting stuff. Dave ------------------------------------------------------------------------------ RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
