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RE: Mortar Field Test

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Harold Sprague wrote: 

> ACI 530 puts you in a bind in the QA requirements.  They give you a bunch
> 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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