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RE: Mortar Field Test

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Bill,

OK.  I am not "done with it".  Your observation points to a major gap in the
ACI 530.1.  It does not do much good in defining a test if there is poorly
written acceptance criteria.  It is worth a comparison to the ACI 318 or ACI
301, and compare acceptance criteria.  Granted it is not exactly crystal
clear in concrete, but it does contain acceptance criteria.

ACI 318 differentiates mix submittals that are predicated on laboratory
conditions as opposed to field specimens.  There is standard deviation
protocols to determine the crushing strength of the samples, and there is a
different acceptance criteria on field specimens.  This approach is a bit
difficult to understand, but it is in the concrete code.  

I wish that there was more guidance in the ACI 530.1.

If I have a critical wall with rather high required stresses, I prefer
requiring the prism tests, Level 3, and I write my own acceptance criteria.


I temper my concern by the fact that I am designing in the elastic range.
When I do a project in seismic country, I get a little more excited and
develop a more rigorous specification to include acceptance criteria, or use
a low R value.

Regards,
Harold O. Sprague

> -----Original Message-----
> From:	Sherman, William [SMTP:ShermanWC(--nospam--at)cdm.com]
> Sent:	Wednesday, October 03, 2001 8:56 AM
> To:	'seaint(--nospam--at)seaint.org'
> Subject:	RE: Mortar Field Test
> 
> Harold Sprague wrote: 
> 
> > ACI 530 puts you in a bind in the QA requirements.  They give you a
> bunch
> of
> > tests, but do not give you acceptance criteria as you find in ACI 318...
> > If you review ACI 530.1 Sect 1.4 B, you will find that masonry mortar
> > testing is not required under the unit strength method.  It is
> confusing.
> > That is why you are better off just referencing the QA requirements of
> ACI
> > 530.1 and be done with it.
> 
> However, ACI 530.1 lists "results of mortar evaluations performed in
> accordance with ASTM C780" in 1.5B to be submitted "when required" and for
> QA Level 3, it requires "verification of proportions of materials in
> mortar
> and grout as delivered to the site". But it is not clear what acceptance
> criteria can be used with ASTM C780 or how mortar proportions are to be
> verified at the site. Following is the text of a message I posted a month
> ago but still have not had any responses to: 
> 
> The 1997 UBC requires that quality assurance be provided to verify that
> "mortar and grout are properly mixed using specified proportions of
> ingredients" (2105.2, item 2). Similarly, ACI 530.1 requires for QA Level
> 3:
> "Verification of proportions of materials in mortar and grout as delivered
> to the site".
> 
> Prior to construction, mix designs can be submitted to verify proposed
> proportions, but what QA procedures can be used to field verify that
> mortar
> and grout have the specified proportions? 
> 
> ASTM C780 provides tests for various properties related to mortar
> proportions but does not provide tests to determine detailed proportions,
> such as specific ratios of portland cement to lime. Preconstruction tests
> and tests during construction can be compared to give an indication of
> consistency of mortar proportions but will not give full detail of
> proportions. Has anyone used ASTM C780 test procedures for a masonry
> construction project? How were the test results used? What ranges in
> variation in consistency are acceptable? 
> 
> ASTM C780 states that the field compressive strength results for mortar
> should not be required to meet the specified compressive strength per ASTM
> C270. UBC Standard 21-16 provides a field compressive test for mortar with
> a
> required minimum compressive strength of 1500 psi. But this standard does
> not state what type of mortar it is applicable to and the code does not
> specifically state when it should be used. Has anyone used this mortar
> test
> method on masonry construction projects? How should this test be used? 
> 

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