[GreenYes] Re: portland cement chemical analysis

[Robert Kirby <kirbgood@no.address>]

If you're asking about using crushed concrete as cement, I believe  
the formation of calcium-silicate crystal structures in portland  
cement is a one-way trip.  Portland cement cannot be crushed and used  
as cement.

The use of crushed concrete as a concrete aggregate is another  
question.  One issue I believe is the balance of excess calcium  
oxides present after cement cures, which may effect the curing of any  
additional concrete added later.  in other words, the process goes  
out of control.

I believe a contractor is being prosecuted for using recycled  
concrete in new concrete in the San Francisco Bay area.  You might  
search the web site in the local newspaper there.

I have heard of recycled concrete being used in Controlled Density  
Fill, a much less stringent spec.

I think there are a number of studies that could be googled.

Bob Kirby


On Aug 30, 2006, at 1:45 PM, Wayne Turner wrote:

Greenyessers,

Slightly off-topic but still recycling related:

Does anyone know how the chemical composition/analysis of portland  
cement changes once it undergoes the setting process?  I'm interested  
in this for the purposes of investigating the chemical properties of  
crushed/pulverized concrete from the C & D waste stream.  As always,  
thanks in advance for any assistance.




Wayne Turner
Assistant Solid Waste Administrator
Winston-Salem/Forsyth County Utilities
phone: (336) 727 8418
fax: (336) 727-8432
email: waynet@no.address


BEGIN:VCARD
VERSION:2.1
X-GWTYPE:USER
FN:Turner, Wayne
TEL;WORK:336-747-7320
ORG:;Utilities
TEL;PREF;FAX:3367479330
EMAIL;WORK;PREF;NGW:WAYNET@no.address
N:Turner;Wayne
END:VCARD




--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups "GreenYes" group.
To post to this group, send email to GreenYes@no.address
To unsubscribe from this group, send email to GreenYes-unsubscribe@no.address
For more options, visit this group at http://groups.google.com/group/GreenYes
-~----------~----~----~----~------~----~------~--~---