Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Non-shrink Grout

[Subject Prev][Subject Next][Thread Prev][Thread Next]
On a recent project I was anchoring new concrete to some existing concrete.
 To anchor the rebar in the existing concrete I called for the use of
cementitious grout.  The plan checker suggested that the note be modified
to read "cementitious non-shrink grout".   Is this a real concern and if so
what is the criteria, and standards for verifying that the grout is
non-shrink.

In the example noted the drilled hole will be 1 inch larger than the bolt. 
Based on shrinkage data for concrete we could expect 0.0008 inches of
shrinkage across the hole.  This should not cause a problem with rebar
development given the size of deformations on the bar.

In the specifications I stated that  "Cementitious grout for anchor
reinforcing steel or threaded rods in concrete shall be Masterflow 928
grout as manufactured by Master Builders or Sika Grout 212 as manufactured
by Sika Corporation, Hi-Flow grout by Euclid Chemical Company".  I have
reasons to believe the checker never refered to the specs.  My impression
is that if this is an issue then either the products specified are
considered non-shrink or else nothing works.

On a related topic I have wondered about the real need to specify
non-shrink grount for base plates.  If for example the grout under the base
plate shrinks 1/16" I would expect the base plate to move with the grout
without any detrimental impact on the building.

Am I missing something?

Your help will be appreciated.

Mark Gilligan