ASTM C780-14b
(Test Method)Standard Test Method for Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry
Standard Test Method for Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry
SIGNIFICANCE AND USE
5.1 During preconstruction and construction evaluations, use of these test methods establishes specific and overall performance characteristics for the mortar system.
5.2 Preconstruction testing of mortars prebatched by weight provides information for the selection of the individual mortar system best suited for the masonry to be constructed. The recommended tests and their significance are as follows:
5.2.1 Consistency determinations by cone penetration (Annex A1) allow gaging the water additions for all mortars included in the preconstruction test series. Even if the mortar consistency as measured at the construction site is at a different penetration value than those measured during the preconstruction tests, the cone preparation test serves to standardize water additions for mortars being considered as alternatives before construction. Additional testing of mortar water content-consistency relationships (Annex A4) will allow relating these two factors to batch-to-batch variations at the construction site.
5.2.2 Consistency retention by cone penetration (Annex A2) using disturbed or undisturbed mortar samples provides a means of establishing the early-age setting and stiffening characteristics of the mortars. Because laboratory testing is conducted under static climatic conditions, consistency retention test results reflect the relative performance of the mortar systems under test. The same general relationships are expected to hold during testing at the construction project, except as they are influenced by jobsite weather conditions.
5.2.3 Mortar water-content determinations (Annex A4) allow measurement of the water content of the mortar mixture. Mortars prebatched using moist masonry sand may be mathematically analyzed for mortar water content; however, this test, when used for preconstruction evaluation, establishes the effectiveness of the test method and serves as the control or base for tests performed at the construction site.
5.2.4 Mortar ...
SCOPE
1.1 This test method covers procedures for the sampling and testing of mortars for composition and for their plastic and hardened properties, either before or during their actual use in construction.
Note 1: Guide C1586 provides guidance on evaluating mortar and clarifies the purpose of both this test method and Specification C270.
Note 2: The testing agency performing this test method should be evaluated in accordance with Practice C1093.
1.2 Preconstruction Evaluation—This test method permits comparisons of mortars made from different materials under simulated field conditions. It is also used to establish baseline values for comparative evaluation of field mortars.
1.3 Construction Evaluation—Use of this method in the field provides a means for quality assurance of field-mixed mortar. It includes methods for verifying the mortar mix proportions, comparing test results for field mortars to preconstruction testing, and determining batch-to-batch uniformity of the mortar.
1.4 The test results obtained under this test method are not required to meet the minimum compressive values in accordance with the property specifications in Specification C270.
1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazards statements, see Section 8.
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Designation: C780 − 14b
StandardTest Method for
Preconstruction and Construction Evaluation of Mortars for
Plain and Reinforced Unit Masonry
This standard is issued under the fixed designation C780; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
INTRODUCTION
This test method provides a standard procedure for sampling and testing mortars for composition
and plastic and hardened properties, either before or during actual construction. The procedures
outlined in the Annexes are considered applicable for evaluating various combinations of portland
cement, lime, and masonry cement for mortars common to plain and reinforced unit masonry
construction.
The test procedures describe methods for the measurement of mortar composition and mortar
properties. No attempt is made to claim or substantiate specific correlations between the measured
properties and mortar performance in the masonry. However, data from these test methods can be
combined with other information to formulate judgments about the quality of the masonry.
Testing using these procedures is limited to the preconstruction evaluation of masonry mortars
within the laboratory, to the evaluation of masonry mortars at the construction site, and in establishing
the degree of quality control exercised during mortar production at the construction site.
1. Scope* 1.4 The test results obtained under this test method are not
required to meet the minimum compressive values in accor-
1.1 Thistestmethodcoversproceduresforthesamplingand
dance with the property specifications in Specification C270.
testing of mortars for composition and for their plastic and
hardened properties, either before or during their actual use in 1.5 The values stated in inch-pound units are to be regarded
construction. as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only
NOTE 1—Guide C1586 provides guidance on evaluating mortar and
and are not considered standard.
clarifies the purpose of both this test method and Specification C270.
NOTE 2—The testing agency performing this test method should be
1.6 This standard does not purport to address all of the
evaluated in accordance with Practice C1093.
safety concerns, if any, associated with its use. It is the
1.2 Preconstruction Evaluation—This test method permits
responsibility of the user of this standard to establish appro-
comparisons of mortars made from different materials under
priate safety and health practices and determine the applica-
simulated field conditions. It is also used to establish baseline
bility of regulatory limitations prior to use.Forspecifichazards
values for comparative evaluation of field mortars.
statements, see Section 8.
1.3 Construction Evaluation—Use of this method in the
2. Referenced Documents
field provides a means for quality assurance of field-mixed
2.1 ASTM Standards:
mortar. It includes methods for verifying the mortar mix
C39/C39M Test Method for Compressive Strength of Cylin-
proportions, comparing test results for field mortars to precon-
drical Concrete Specimens
struction testing, and determining batch-to-batch uniformity of
C109/C109M Test Method for Compressive Strength of
the mortar.
Hydraulic Cement Mortars (Using 2-in. or [50-mm] Cube
Specimens)
This test method is under the jurisdiction ofASTM Committee C12 on Mortars
and Grouts for Unit Masonry and is the direct responsibility of Subcommittee
C12.02 on Research and Methods of Test. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 1, 2014. Published January 2015. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1974. Last previous edition approved in 2014 as C780 – 14a. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C0780-14B. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C780 − 14b
C128 Test Method for Density, Relative Density (Specific batches are sampled and used in establishing the plastic and
Gravity), and Absorption of Fine Aggregate hardened properties of the mixtures. Because all the trial
C173/C173M Test Method forAir Content of Freshly Mixed mixturesareprebatchedbyweight,additionalcharacteristicsof
Concrete by the Volumetric Method themortarsmaybecalculatedandusedinananalysisofmortar
C185 Test Method for Air Content of Hydraulic Cement performance.
Mortar
4.2 During actual construction, evaluation of masonry mor-
C187 Test Method for Amount of Water Required for Nor-
tars is possible by sampling the mortar at various stages of
mal Consistency of Hydraulic Cement Paste
construction, and performing tests on both its plastic and
C231 Test Method for Air Content of Freshly Mixed Con-
hardened properties. The test results permit further verification
crete by the Pressure Method
of preconstruction testing, and reflect batch-to-batch variations
C270 Specification for Mortar for Unit Masonry
introduced during mortar production and use at the construc-
C470/C470M Specification for Molds for Forming Concrete
tion site. More immediate corrective action for the mixing
Test Cylinders Vertically
procedure is thereby attainable.
C511 Specification for Mixing Rooms, Moist Cabinets,
4.3 The following test methods may be singly or collec-
Moist Rooms, and Water Storage Tanks Used in the
tively incorporated into the testing to establish mortar
Testing of Hydraulic Cements and Concretes
composition, and mortar plastic and hardened properties:
C617 Practice for Capping Cylindrical Concrete Specimens
4.3.1 Annex A1—Consistency by Cone Penetration Test
C1093 Practice for Accreditation of Testing Agencies for
Method,
Masonry
4.3.2 Annex A2—Consistency Retention of Mortars for
C1180 Terminology of Mortar and Grout for Unit Masonry
Unit Masonry,
C1231 Practice for Use of Unbonded Caps in Determination
4.3.3 Annex A3—Initial Consistency and Consistency Re-
of Compressive Strength of Hardened Concrete Cylinders
tention or Board Life of Masonry Mortars Using a Modified
C1586 Guide for Quality Assurance of Mortars
Concrete Pentrometer,
E11 Specification for Woven Wire Test Sieve Cloth and Test
4.3.4 Annex A4—Mortar Aggregate Ratio Test Method,
Sieves
4.3.5 Annex A5—Mortar Air Content Test Method,
3. Terminology
4.3.6 Annex A6—Compressive Strength of Molded Ma-
sonry Mortar Cylinders and Cubes, and
3.1 Terminology defined in Terminology C1180 shall apply
for this test method.
5. Significance and Use
3.2 Definitions of Terms Specific to This Standard:
3.2.1 Termspeculiartotestingmasonrymortarareindicated
5.1 During preconstruction and construction evaluations,
and defined below:
use of these test methods establishes specific and overall
3.2.2 disturbed sample—any plastic mortar test sample
performance characteristics for the mortar system.
which is taken at some time after mixing and bulk sampling,
5.2 Preconstruction testing of mortars prebatched by weight
that is further remixed or molded immediately prior to test, or
provides information for the selection of the individual mortar
both.
system best suited for the masonry to be constructed. The
3.2.3 undisturbed sample—any plastic mortar test sample
recommended tests and their significance are as follows:
molded immediately after mixing and sampling that sits on a
5.2.1 Consistency determinations by cone penetration (An-
vibration-free surface until tested.
nex A1) allow gaging the water additions for all mortars
included in the preconstruction test series. Even if the mortar
3.3 During sampling, the following descriptions will iden-
consistencyasmeasuredattheconstructionsiteisatadifferent
tify sample locations:
penetration value than those measured during the preconstruc-
3.3.1 Batch mixer samples are those obtained during or
tion tests, the cone preparation test serves to standardize water
immediately after the discharge of the mortar from the batch
additions for mortars being considered as alternatives before
mixer.
construction. Additional testing of mortar water content-
3.3.2 Mortar board samples are those obtained from the
consistency relationships (AnnexA4) will allow relating these
mortar board after some established time period from the end
two factors to batch-to-batch variations at the construction site.
of mixing, and before retempering. Retempered mortar board
5.2.2 Consistencyretentionbyconepenetration(AnnexA2)
samples are those obtained from the mortar board after
using disturbed or undisturbed mortar samples provides a
retempering. Since mortar on a mason’s mortar board is
means of establishing the early-age setting and stiffening
disturbed by the activity of the mason, samples from a mason’s
characteristics of the mortars. Because laboratory testing is
mortar board shall be so identified to differentiate them from
conducted under static climatic conditions, consistency reten-
samples taken from a mortar board used exclusively for test
tion test results reflect the relative performance of the mortar
purposes.
systems under test. The same general relationships are ex-
4. Summary of Test Method
pected to hold during testing at the construction project, except
4.1 Preconstruction evaluation of mortar systems involves as they are influenced by jobsite weather conditions.
the preparation of one or more trial batches which are mixed in 5.2.3 Mortar water-content determinations (Annex A4) al-
the laboratory using mechanical batch mixers. These trial low measurement of the water content of the mortar mixture.
C780 − 14b
Mortars prebatched using moist masonry sand may be math- unsatisfactoryproportioningormixingprocedure,forexample,
ematically analyzed for mortar water content; however, this cement to aggregate, mortar water, or air content tests.
test, when used for preconstruction evaluation, establishes the
5.3.2 Consistencyretentionbyconepenetration(AnnexA2)
effectiveness of the test method and serves as the control or
tests establishes the early-age setting and stiffening character-
base for tests performed at the construction site.
istics of the mortar. These properties are influenced by mix
5.2.4 Mortar aggregate ratio testing (Annex A4) provides a
proportions and ingredients, weather conditions, effects of
method for determining the ratio of aggregate-to-cementitious
chemical additives, and mixing time.
materials. The sieving operation employed during this test is
5.3.3 Individual and repeated evaluations of mortar water
incapable of separating an individual cementitious material
content (Annex A4) show the ability of the mixer operator to
when more than one such material is used, but can accurately
properly and consistently add water to the mixer.
establish the aggregate-to-cementitious materials ratio of the
5.3.4 Individual and repeated tests for mortar aggregate
mixture.
ratio (Annex A4) show the ability of the mixer operator to
5.2.5 Mortar air-content testing (Annex A5) is useful in
properly and consistently add the cementitious material and
establishingthevalueofthiscomponentofthemortar.Thistest
sand to the mixer, and will establish batch-to-batch variations
is of particular importance in evaluating mortars that contain
in the composition of the mortar.
air-entraining portland cement, air-entraining lime, masonry
5.3.5 Individual and repetitive tests for mortar air content
cement or any combination thereof.
(Annex A5) show the changes caused by variations in mixing
5.2.6 Compressive strength testing (Annex A6) of molded
time, mixing efficiency and other factors.
mortar cylinders and cubes establishes one of the characteris-
5.3.6 Comparison of compressive strength tests (AnnexA6)
tics of hardened mortar. Mortar compressive strength test
of field batched mortars to preconstruction mortar compression
valuesarenotrepresentativeoftheactualcompressivestrength
tests, each conducted in accordance with this test method, can
of mortar in the assembly and are not appropriate for use in
be used to identify variations in mortar mix constituents and/or
predicting the compressive strength that would be attained by
proportions. Variations in compressive strength values typi-
the mortar in the masonry assembly. The measured compres-
cally indicate changes in mix water content, mixing
sive strength of a molded mortar specimen is almost always
procedures, mix materials, material proportions, and environ-
lower than the strength of the same mortar in the wall,
primarily as a result of differences in mortar water content and mental conditions.
specimen shape. Mortar compressive strength is influenced by
NOTE 4—Variations in the measured compressive strengths of field-
mortar water content at the time of set. Because molded mortar
sampled mortar and between the measured compressive strengths of
specimensarenotincontactwithabsorptivemasonryunitsand
construction and pre-construction mortar samples should be expected.
are not subjected to other mechanisms of water loss, they have
Many of these variations result from sampling mortar from the mixer or
higher water contents than mortar in the wall. Higher water mortarboard and do not necessarily translate into significant mortar
strength variations in the wall. Unit suction will remove water from the
contentsalmostalwaysresultinlowerstrengths.Specimensize
mortar in the wall and the curing conditions are different. However,
and shape also affect compressive strength. Cylinders and
significant variation between measured compression strength values
cubes exhibit different strengths even when made from the
should prompt evaluation of probable causes of this variation. Conducting
same mortar mix. Both of these specimen configurations yield
companion mortar aggregate ratio tests would assist in determining if
lower strengths than what would be attained if a specimen
changes in mix constituents and proportions are the likely cause. (See
havingthesamesizeandconfigurationofatypicalmortarjoint 5.2.6 for additional information).
could be reliably tested.
6. Test Method Limitations
NOTE3—Whencubeandcylindertestspecimensfromlikemixturesare
to be compared, the cylinder compressive strength is approximately 85 %
6.1 During mortar aggregate ratio testing, no attempt has
of the cube compressive strength.
been made to establish the proportions
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C780 − 14a C780 − 14b
Standard Test Method for
Preconstruction and Construction Evaluation of Mortars for
Plain and Reinforced Unit Masonry
This standard is issued under the fixed designation C780; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
INTRODUCTION
This test method provides a standard procedure for sampling and testing mortars for composition
and plastic and hardened properties, either before or during actual construction. The procedures
outlined in the Annexes are considered applicable for evaluating various combinations of portland
cement, lime, and masonry cement for mortars common to plain and reinforced unit masonry
construction.
The test procedures describe methods for the measurement of mortar composition and mortar
properties. No attempt is made to claim or substantiate specific correlations between the measured
properties and mortar performance in the masonry. However, data from these test methods can be
combined with other information to formulate judgments about the quality of the masonry.
Testing using these procedures is limited to the preconstruction evaluation of masonry mortars
within the laboratory, to the evaluation of masonry mortars at the construction site, and in establishing
the degree of quality control exercised during mortar production at the construction site.
1. Scope*
1.1 This test method covers procedures for the sampling and testing of mortars for composition and for their plastic and
hardened properties, either before or during their actual use in construction.
NOTE 1—Guide C1586 provides guidance on evaluating mortar and clarifies the purpose of both this test method and Specification C270.
NOTE 2—The testing agency performing this test method should be evaluated in accordance with Practice C1093.
1.2 Preconstruction Evaluation—This test method permits comparisons of mortars made from different materials under
simulated field conditions. It is also used to establish baseline values for comparative evaluation of field mortars.
1.3 Construction Evaluation—Use of this method in the field provides a means for quality assurance of field-mixed mortar. It
includes methods for verifying the mortar mix proportions, comparing test results for field mortars to preconstruction testing, and
determining batch-to-batch uniformity of the mortar.
1.4 The test results obtained under this test method are not required to meet the minimum compressive values in accordance
with the property specifications in Specification C270.
1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use. For specific hazards statements, see Section 8.
This test method is under the jurisdiction of ASTM Committee C12 on Mortars and Grouts for Unit Masonry and is the direct responsibility of Subcommittee C12.02
on Research and Methods of Test.
Current edition approved Aug. 1, 2014Dec. 1, 2014. Published September 2014January 2015. Originally approved in 1974. Last previous edition approved in 2014 as
C780 – 14.C780 – 14a. DOI: 10.1520/C0780-14A.10.1520/C0780-14B.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C780 − 14b
2. Referenced Documents
2.1 ASTM Standards:
C39/C39M Test Method for Compressive Strength of Cylindrical Concrete Specimens
C109/C109M Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50-mm] Cube Specimens)
C128 Test Method for Density, Relative Density (Specific Gravity), and Absorption of Fine Aggregate
C173/C173M Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method
C185 Test Method for Air Content of Hydraulic Cement Mortar
C187 Test Method for Amount of Water Required for Normal Consistency of Hydraulic Cement Paste
C231 Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method
C270 Specification for Mortar for Unit Masonry
C470/C470M Specification for Molds for Forming Concrete Test Cylinders Vertically
C511 Specification for Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic
Cements and Concretes
C617 Practice for Capping Cylindrical Concrete Specimens
C1093 Practice for Accreditation of Testing Agencies for Masonry
C1180 Terminology of Mortar and Grout for Unit Masonry
C1231 Practice for Use of Unbonded Caps in Determination of Compressive Strength of Hardened Concrete Cylinders
C1586 Guide for Quality Assurance of Mortars
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
3. Terminology
3.1 Terminology defined in Terminology C1180 shall apply for this test method.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 Terms peculiar to testing masonry mortar are indicated and defined below:
3.2.2 disturbed sample—any plastic mortar test sample which is taken at some time after mixing and bulk sampling, that is
further remixed or molded immediately prior to test, or both.
3.2.3 undisturbed sample—any plastic mortar test sample molded immediately after mixing and sampling that sits on a
vibration-free surface until tested.
3.3 During sampling, the following descriptions will identify sample locations:
3.3.1 Batch mixer samples are those obtained during or immediately after the discharge of the mortar from the batch mixer.
3.3.2 Mortar board samples are those obtained from the mortar board after some established time period from the end of
mixing, and before retempering. Retempered mortar board samples are those obtained from the mortar board after retempering.
Since mortar on a mason’s mortar board is disturbed by the activity of the mason, samples from a mason’s mortar board shall be
so identified to differentiate them from samples taken from a mortar board used exclusively for test purposes.
4. Summary of Test Method
4.1 Preconstruction evaluation of mortar systems involves the preparation of one or more trial batches which are mixed in the
laboratory using mechanical batch mixers. These trial batches are sampled and used in establishing the plastic and hardened
properties of the mixtures. Because all the trial mixtures are prebatched by weight, additional characteristics of the mortars may
be calculated and used in an analysis of mortar performance.
4.2 During actual construction, evaluation of masonry mortars is possible by sampling the mortar at various stages of
construction, and performing tests on both its plastic and hardened properties. The test results permit further verification of
preconstruction testing, and reflect batch-to-batch variations introduced during mortar production and use at the construction site.
More immediate corrective action for the mixing procedure is thereby attainable.
4.3 The following test methods may be singly or collectively incorporated into the testing to establish mortar composition, and
mortar plastic and hardened properties:
4.3.1 Annex A1—Consistency by Cone Penetration Test Method,
4.3.2 Annex A2—Consistency Retention of Mortars for Unit Masonry,
4.3.3 Annex A3—Initial Consistency and Consistency Retention or Board Life of Masonry Mortars Using a Modified Concrete
Pentrometer,
4.3.4 Annex A4—Mortar Aggregate Ratio Test Method,
4.3.5 Annex A5—Mortar Air Content Test Method,
4.3.6 Annex A6—Compressive Strength of Molded Masonry Mortar Cylinders and Cubes, and
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
C780 − 14b
5. Significance and Use
5.1 During preconstruction and construction evaluations, use of these test methods establishes specific and overall performance
characteristics for the mortar system.
5.2 Preconstruction testing of mortars prebatched by weight provides information for the selection of the individual mortar
system best suited for the masonry to be constructed. The recommended tests and their significance are as follows:
5.2.1 Consistency determinations by cone penetration (Annex A1) allow gaging the water additions for all mortars included in
the preconstruction test series. Even if the mortar consistency as measured at the construction site is at a different penetration value
than those measured during the preconstruction tests, the cone preparation test serves to standardize water additions for mortars
being considered as alternatives before construction. Additional testing of mortar water content-consistency relationships (Annex
A4) will allow relating these two factors to batch-to-batch variations at the construction site.
5.2.2 Consistency retention by cone penetration (Annex A2) using disturbed or undisturbed mortar samples provides a means
of establishing the early-age setting and stiffening characteristics of the mortars. Because laboratory testing is conducted under
static climatic conditions, consistency retention test results reflect the relative performance of the mortar systems under test. The
same general relationships are expected to hold during testing at the construction project, except as they are influenced by jobsite
weather conditions.
5.2.3 Mortar water-content determinations (Annex A4) allow measurement of the water content of the mortar mixture. Mortars
prebatched using moist masonry sand may be mathematically analyzed for mortar water content; however, this test, when used for
preconstruction evaluation, establishes the effectiveness of the test method and serves as the control or base for tests performed
at the construction site.
5.2.4 Mortar aggregate ratio testing (Annex A4) provides a method for determining the ratio of aggregate-to-cementitious
materials. The sieving operation employed during this test is incapable of separating an individual cementitious material when
more than one such material is used, but can accurately establish the aggregate-to-cementitious materials ratio of the mixture.
5.2.5 Mortar air-content testing (Annex A5) is useful in establishing the value of this component of the mortar. This test is of
particular importance in evaluating mortars that contain air-entraining portland cement, air-entraining lime, masonry cement or any
combination thereof.
5.2.6 Compressive strength testing (Annex A6) of molded mortar cylinders and cubes establishes one of the characteristics of
hardened mortar. Mortar compressive strength test values are not representative of the actual compressive strength of mortar in the
assembly and are not appropriate for use in predicting the compressive strength that would be attained by the mortar in the masonry
assembly. The measured compressive strength of a molded mortar specimen is almost always lower than the strength of the same
mortar in the wall, primarily as a result of differences in mortar water content and specimen shape. Mortar compressive strength
is influenced by mortar water content at the time of set. Because molded mortar specimens are not in contact with absorptive
masonry units and are not subjected to other mechanisms of water loss, they have higher water contents than mortar in the wall.
Higher water contents almost always result in lower strengths. Specimen size and shape also affect compressive strength. Cylinders
and cubes exhibit different strengths even when made from the same mortar mix. Both of these specimen configurations yield lower
strengths than what would be attained if a specimen having the same size and configuration of a typical mortar joint could be
reliably tested.
NOTE 3—When cube and cylinder test specimens from like mixtures are to be compared, the cylinder compressive strength is approximately 85 % of
the cube compressive strength.
5.3 Testing during the actual construction may employ one or more of the test methods described in 4.2. Repetitive testing using
these test methods on consecutive or intermittent batches provides a method for measurement of batch-to-batch variations in the
mortar production. Testing during actual construction may be referenced to laboratory testing and used to predict later age mortar
characteristics. In addition to the comments in 5.2, the following test meanings may be obtained from construction project testing:
5.3.1 Consistency by cone penetration (Annex A1) is used as a quick reference for indicating batch-to-batch variations in mix
ingredients and mixing time. Erratic consistency readings indicate poor control during batching and mixing, but they do not
indicate if cement, sand, or water additions are improper. Other test methods must be used to isolate and identify the unsatisfactory
proportioning or mixing procedure, for example, cement to aggregate, mortar water, or air content tests.
5.3.2 Consistency retention by cone penetration (Annex A2) tests establishes the early-age setting and stiffening characteristics
of the mortar. These properties are influenced by mix proportions and ingredients, weather conditions, effects of chemical additives,
and mixing time.
5.3.3 Individual and repeated evaluations of mortar water content (Annex A4) show the ability of the mixer operator to properly
and consistently add water to the mixer.
5.3.4 Individual and repeated tests for mortar aggregate ratio (Annex A4) show the ability of the mixer operator to properly and
consistently add the cementitious material and sand to the mixer, and will establish batch-to-batch variations in the composition
of the mortar.
5.3.5 Individual and repetitive tests for mortar air content (Annex A5) show the changes caused by variations in mixing time,
mixing efficiency and other factors.
...
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