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Looking for information to a construction problem located in Northern 
California regarding masonry walls... specifically grout.  I have designed 
18' tall masonry walls.  Supported @ the top, f'm=1500 psi, special 
inspections, 8" thick.  Temperatures have been cool but not cold.  Recent 
grout tests are showing a low compressive break.   500 psi @ 7 days and 1400 
psi @ 28 days.  1991 UBC code requires 2000 psi minimum.  After some 
investigation, I found the mix design calls for 5,000 lbs. of type F 
fly-ash.  Is this even possible???  The total numbers add up to 12 yds in a 
9 yd truck.  Core samples have also been taken resulting in a 1750 psi 
average strength.  Since this flyash has been noticed, different grout 
supplier has been selected.  Using the same design without the flyash... his 
7 day breaks have been around 1800 psi.
        The only place I can find reference to masonry grout cores is title 
24 of the UBC which is not in effect for this building.
        Question.... What short-term/long-term effects will fly-ash have on 
grout?  What other references are available regarding masonry grout cores?  
Currently the building official is leaning towards tearing down 3,000 sq. 
ft. of wall and maybe an additional 20,000 sq. ft. more.  Any suggestions or 
help would be appreciated.

        Thanks !!

        Jeff Spence, PE