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RE: Mortar Testing

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Bill,

In case you have are not aware, when you test grout, the grout sample
should be made by using masonry units as the form.  This is generally
done with a pinwheel type configuration of the masonry units so that a
hollow square shaped section is left in the middle.  Building paper or
such is used as a bond breaker between the grout and the masonry units.
This configuration allows the masonry units to absorb a lot of the water
from the grout much like what will happen in the field application (i.e.
the actual wall is building).  The masonry units are then stripped away
(after the grout has sufficiently cured) leaving just the grout test
sample.

I believe that Arvel also mentioned this method along with a proprietary
form that could be used instead.

I can get you a sketch/figure that illustrates what I described above if
my previous blather is not clear.  Or if you locate a copy of NCMA's TEK
Note 9-4, there is a figure in it that shows it (NCMA TEK notes are
available online through their website, I believe).

HTH,

Scott
Adrian, MI


On Tue, 5 Apr 2005, Bill Allen, S.E. wrote:

> Dave -
>
> My question was relative to grout, not mortar.
>
> Good info, though.
>
> T. William (Bill) Allen, S.E. (CA #2607)
> ALLEN DESIGNS
> Consulting Structural Engineers
> http://www.AllenDesigns.com
> V (949) 248-8588	 .	 F (949) 209-2509
>
> -----Original Message-----
> From: D. Woodham [mailto:dwoodham(--nospam--at)ana-usa.com]
> Sent: Tuesday, April 05, 2005 2:45 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: Mortar Testing
>
> Bill,
>
>
>
> From ASTM C 270  (X1.6.3.2):
>
>
>
> Perhaps because of the previously noted confusion regarding mortar and
> concrete, the importance of compressive strength of mortar is
> overemphasized. Compressive strength should not be the sole criterion for
> mortar selection. Bond strength is generally more important, as is good
> workability and water rententivity, both of which are required for maximum
> bond.  Flexural strength is also important because it measures the ability
> of a mortar to resist cracking.  Often overlooked is the size/shape of
> mortar joints in that the ultimate compressive load carrying capacity of a
> typical 3/8 in. (9.5 mm) bed joint will probably be well over twice the
> value obtained when the mortar is tested as a 2 in. (50.8 mm) cube.  Mortars
>
> should typically be weaker than the masonry units, so that any cracks will
> occur in the mortar joints where they are more easily repaired.
>
>
>
> Regards,
>
> Dave Woodham
>
> Atkinson-Noland & Assoc.
>
>
>
>
>
> ----- Original Message -----
> From: "Bill Allen, S.E." <T.W.Allen(--nospam--at)cox.net>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Tuesday, April 05, 2005 3:05 PM
> Subject: RE: Mortar Testing
>
>
> > This thread reminds me of a question I've been meaning to ask.
> >
> > With regards to grout, when should it be tested? The w/c ratio has to be
> > really high (producing an 8-9 in slump) so that the block has some water
> > to
> > absorb when placing the grout and doesn't suck it all out. However, with a
> > w/c ratio so high, I doubt if a satisfactory sample can be cast. After
> > all,
> > the in-situ condition of grout has a w/c ratio which is more normal range
> > once the excessive water is removed by the block. It would seem to me that
> > the sample should be cast before the water is added, but that sounds like
> > a
> > complicated process.
> >
> > Any enlightenment would be appreciated.
> >
> > T. William (Bill) Allen, S.E. (CA #2607)
> > ALLEN DESIGNS
> > Consulting Structural Engineers
> > http://www.AllenDesigns.com
> > V (949) 248-8588 . F (949) 209-2509
> >
> > -----Original Message-----
> > From: Sherman, William [mailto:ShermanWC(--nospam--at)cdm.com]
> > Sent: Tuesday, April 05, 2005 1:38 PM
> > To: seaint(--nospam--at)seaint.org
> > Subject: RE: Mortar Testing
> >
> > I just finished typing an email to a co-worker on this very subject.
> > Following is what I wrote:
> >
> > I have deleted testing of mortar during construction from the project
> > specifications for the following reasons: Sections 3.1 and 3.3 of ASTM
> > C270-03 state that this standard is not to be used for field testing of
> > mortar or to determine compliance of field sampled mortar with the
> > specification; ASTM C780 provides methods for field testing of masonry
> > mortar but it also states that such testing should not be used to
> > determine compliance with compressive strength in ASTM C270. The reason
> > mortar is generally not field tested is that the mixed mortar has a
> > higher water content than the mortar in the constructed wall, due to
> > absorption of water by the CMU. Thus, compressive strengths of field
> > mixed mortar alone would be expected to be lower than laboratory tests
> > that use defined water contents.
> >
> > Therefore, one should generally not specify field testing of mortar. UBC
> > does have a special test method using masonry units and mortar - but if
> > we are really concerned with strength of masonry, we should specify
> > prism testing. However, prism testing is not required by the code if the
> > specified compressive strength of masonry is within the permissible
> > requirements for the "Unit Strength Method".
> >
> >
> > William C. Sherman, PE
> > (Bill Sherman)
> > CDM, Denver, CO
> > Phone: 303-298-1311
> > Fax: 303-293-8236
> > email: shermanwc(--nospam--at)cdm.com
> >
> >
> >> -----Original Message-----
> >> From: Kestner, James W. [mailto:jkestner(--nospam--at)somervilleinc.com]
> >> Sent: Tuesday, April 05, 2005 2:30 PM
> >> To: SEAINT
> >> Subject: Mortar Testing
> >>
> >> Why does the ACI 530, 3.7B, require only lab compressive
> >> strength testing (ASTM C270) for acceptance of mortar? Field
> >> testing (ASTM C780) is only to verify consistency of
> >> materials and procedures, NOT FOR MORTAR STRENGTH. Yet, the
> >> ASTM C780 tests for compressive strength.  This seems like
> >> the mason and mortar suppliers have lobbied hard for this
> >> provision to remove any checks and balance on their in place
> >> work. Other than a prism test, what other basis do we have to
> >> evaluate the strength of mortar that we are actually getting
> >> in the field?
> >>
> >> I realize that I'm really only interested in the strength of
> >> the entire assembly, but if it is cost prohibitive to test
> >> the prism assembly, then if I test each component
> >> individually and it comes up to strength, than I would think
> >> that the assembly is acceptable.
> >>
> >>
> >> > Jim K.
> >> >
> >>
> >>
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