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RE: Reinforcing grades

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 Just a comment---I recently saw a project where all reinforcing #7 and
larger was specified at Grade 75. Looking at the grade stamps was obviously
important, and the inspector found a few bars that were stamped for gr 60.
They happened to be column bars in a previously cast column; the inspector
had the contractor cut out 4-24 inch long samples for testing (4 bars out of
16 in the column) and then mechanical splice the next lift of bars onto the
cut sections. The contractor checked with the fabricator, who responded that
the mill had mis-stamped that heat as grade 60 but assured that the bars
were indeed grade 75. The source accountability forms indicated grade 75,
but mill certs are not always perfect. This fostered speculation on the part
of the A/E, owner, and everyone else, so the bars were tested. They did test
to more than gr 75 (hooray) but then the city building official asked if
that guaranteed that the other bars in that column were also grade 75. It
happened again in a 22 bar column three floors up and this time all 22 bars
were tested--also to grade 75. 

So---be careful when looking at the bar stamps. Also, grade 75 is a pain in
the ass to procure quickly when there are problems---so think hard about
where and when it is used. 

Finally, look at section 1.7 and appendix A of the CRSI Manual of Standard
Practice for identification marks used by steel producers in the US.
Overseas producers may or may not follow these!!!

Richard W. Stone, P.E.
Project Executive
Technical Services/Project Management/Estimating
Concept Design/Engineering/Quality Assurance
 
Madison Concrete Construction Company
130 Quaker lane
Malvern, PA 19355-2479
email: rstone(--nospam--at)madisonconcrete.com
Voice:       610.695.8800
Facsimile: 610.695.8678
 
Nextel:      610.496.5764
 
 
Visit our webpage at  www.madisonconcrete.com  !!!!
 
 



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