ASTM C780-23

Standard Test Methods 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 These test methods cover 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 these test methods and Specification C270.
Note 2: The testing agency performing these test methods should be evaluated in accordance with Practice C1093.  
1.2 Preconstruction Evaluation—These test methods permit comparisons of mortars made from different materials under simulated field conditions. They are also used to establish baseline values for comparative evaluation of field mortars.  
1.3 Construction Evaluation—Use of these methods in the field provide a means for quality assurance of field-mixed mortar. They include 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 these test methods 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 The text of this standard references notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.  
1.7 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific ...

General Information

• Status: Published
• Publication Date: 30-Jun-2023
• ICS: 91.100.10 - Cement. Gypsum. Lime. Mortar
• Technical Committee: C12 - Mortars and Grouts for Unit Masonry
• Drafting Committee: C12.02 - Research and Methods of Test

Relations

• Refers: ASTM C231/C231M-24 - Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method
• Effective Date: 01-Jan-2024
• Refers: ASTM C173/C173M-24 - Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method
• Effective Date: 01-Jan-2024
• Refers: ASTM C109/C109M-23 - Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 50 mm [2 in.] Cube Specimens)
• Effective Date: 15-Dec-2023
• Refers: ASTM C39/C39M-23 - Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens
• Effective Date: 01-Dec-2023
• Refers: ASTM C1231/C1231M-23 - Standard Practice for Use of Unbonded Caps in Determination of Compressive Strength of Hardened Cylindrical Concrete Specimens
• Effective Date: 01-Oct-2023
• Refers: ASTM C617/C617M-23 - Standard Practice for Capping Cylindrical Concrete Specimens
• Effective Date: 01-Oct-2023
• Refers: ASTM C173/C173M-23 - Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method
• Effective Date: 01-Sep-2023
• Refers: ASTM C185-20 - Standard Test Method for Air Content of Hydraulic Cement Mortar
• Effective Date: 01-Apr-2020
• Refers: ASTM C185-19 - Standard Test Method for Air Content of Hydraulic Cement Mortar
• Effective Date: 01-Dec-2019
• Refers: ASTM C270-19a - Standard Specification for Mortar for Unit Masonry
• Effective Date: 01-May-2019
• Refers: ASTM C270-19ae1 - Standard Specification for Mortar for Unit Masonry
• Effective Date: 01-May-2019
• Refers: ASTM C270-19 - Standard Specification for Mortar for Unit Masonry
• Effective Date: 01-Feb-2019
• Refers: ASTM C1586-18 - Standard Guide for Quality Assurance of Mortars
• Effective Date: 15-Dec-2018
• Refers: ASTM C1180-18 - Standard Terminology of Mortar and Grout for Unit Masonry
• Effective Date: 01-Dec-2018
• Refers: ASTM C1586-17 - Standard Guide for Quality Assurance of Mortars
• Effective Date: 15-Dec-2017

Overview

ASTM C780-23: Standard Test Methods for Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry establishes procedures for evaluating mortar composition and properties during both preconstruction and active construction phases. Developed by ASTM, this standard supports quality control and assurance processes by defining testing methods for mortars used in unit masonry, including those for both plain and reinforced applications.

ASTM C780-23 is designed for field and laboratory use, helping specifiers, contractors, and engineers to assess fresh and hardened mortar properties, compare different mortar systems, and maintain consistency throughout a construction project. By facilitating the selection and verification of mortars, the standard aids in achieving reliable performance in masonry assemblies.

Key Topics

• Sampling Procedures: Methods for collecting representative samples from materials intended for construction, ensuring accuracy in laboratory and field testing.
• Consistency and Retention Tests: Use of cone penetrations and other methods to evaluate mortar workability, setting, and stiffening characteristics, crucial for both handling and placement.
• Water Content and Aggregate Ratio: Techniques for measuring the water content and analyzing the ratio of aggregates to cementitious materials, critical for maintaining batch-to-batch uniformity.
• Air Content Evaluation: Procedures for determining the air content within mortar, supporting assessment of performance when air-entraining components are used.
• Compressive Strength Testing: Methods for evaluating the strength of molded mortar specimens, providing data on hardened mortar but not directly predicting in-wall performance.
• Quality Control in Construction: Guidelines for repetitive testing and data comparison, enabling monitoring of field-produced mortar consistency, ingredient accuracy, and adherence to specified mix designs.

Applications

ASTM C780-23 is highly practical for a wide range of masonry construction projects, including commercial, residential, and infrastructure work. Key applications include:

• Preconstruction Mortar Evaluation: Selection and comparison of mortar types and materials under simulated field conditions to establish baseline expectations before masonry work begins.
• Quality Assurance During Construction: Implementation of regular field sampling and testing to verify mix proportions, consistency, and other properties, ensuring conformity to project specifications.
• Troubleshooting and Verification: Investigation of performance issues or inconsistencies by comparing field test results to preconstruction values, supporting process improvement and corrective action.
• Documentation and Reporting: Facilitates standardized recording and communication of test data, supporting contractual quality requirements and providing evidence of compliance.
• Training and Accreditation: Offers a foundation for laboratory accreditation and personnel training on best practices in mortar testing, as referenced by related ASTM standards.

Related Standards

ASTM C780-23 works in conjunction with several other industry standards and guidelines, fostering a comprehensive approach to mortar evaluation and masonry construction quality:

• ASTM C270: Specification for Mortar for Unit Masonry - outlines requirements for mortar types and mixes.
• ASTM C1093: Practice for Accreditation of Testing Agencies for Masonry - provides criteria for laboratory accreditation.
• ASTM C1586: Guide for Quality Assurance of Mortars - offers broader context for using mortar test methods, including C780.
• ASTM C1324: Test Method for Examination and Analysis of Hardened Masonry Mortar - for in-depth analysis of hardened mortar.
• ASTM C185: Test Method for Air Content of Hydraulic Cement Mortar.
• ASTM C128: Test Method for Fine Aggregate Density and Absorption.

Practical Value

Utilizing ASTM C780-23 in construction projects ensures:

• Improved Quality Control: Enables consistent and reliable masonry by monitoring mortar properties during all phases.
• Compliance and Accountability: Supports compliance with project specifications and regulatory requirements.
• Risk Reduction: Minimizes costly mistakes by identifying issues in mix accuracy, ingredient consistency, or application technique early in the process.
• Enhanced Communication: Provides uniform procedures and terminology, fostering clearer collaboration between architects, engineers, contractors, and quality assurance teams.

For any masonry project requiring robust preconstruction or in-field verification of mortar properties, ASTM C780-23 is an indispensable tool for quality assurance, project efficiency, and long-term masonry performance.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C780 − 23
Standard Test Methods 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
These test methods provide standard procedures 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 these test methods are
not required to meet the minimum compressive values in
1.1 These test methods cover procedures for the sampling
accordance with the property specifications in Specification
and testing of mortars for composition and for their plastic and
C270.
hardened properties, either before or during their actual use in
construction.
1.5 The values stated in inch-pound units are to be regarded
NOTE 1—Guide C1586 provides guidance on evaluating mortar and as standard. The values given in parentheses are mathematical
clarifies the purpose of both these test methods and Specification C270.
conversions to SI units that are provided for information only
NOTE 2—The testing agency performing these test methods should be
and are not considered standard.
evaluated in accordance with Practice C1093.
1.6 The text of this standard references notes and footnotes
1.2 Preconstruction Evaluation—These test methods permit
comparisons of mortars made from different materials under that provide explanatory material. These notes and footnotes
simulated field conditions. They are also used to establish (excluding those in tables and figures) shall not be considered
baseline values for comparative evaluation of field mortars.
as requirements of the standard.
1.3 Construction Evaluation—Use of these methods in the
1.7 This standard does not purport to address all of the
field provide a means for quality assurance of field-mixed
safety concerns, if any, associated with its use. It is the
mortar. They include methods for verifying the mortar mix
responsibility of the user of this standard to establish appro-
proportions, comparing test results for field mortars to precon-
priate safety, health, and environmental practices and deter-
struction testing, and determining batch-to-batch uniformity of
mine the applicability of regulatory limitations prior to use.
the mortar.
For specific hazards statements, see Section 8.
1.8 This international standard was developed in accor-
dance with internationally recognized principles on standard-
These test methods are under the jurisdiction of ASTM Committee C12 on
Mortars and Grouts for Unit Masonry and are the direct responsibility of Subcom- ization established in the Decision on Principles for the
mittee C12.02 on Research and Methods of Test.
Development of International Standards, Guides and Recom-
Current edition approved July 1, 2023. Published July 2023. Originally approved
mendations issued by the World Trade Organization Technical
in 1974. Last previous edition approved in 2020 as C780 – 20. DOI: 10.1520/
C0780-23. Barriers to Trade (TBT) Committee.
*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 − 23
2. Referenced Documents 3.2.4 mortar board samples, n—mortar samples that are
obtained from the mortar board after some established time
2.1 ASTM Standards:
period from the end of mixing, and before retempering.
C39/C39M Test Method for Compressive Strength of Cylin-
3.2.4.1 Discussion—Retempered mortar board samples are
drical Concrete Specimens
those obtained from the mortar board after retempering. Since
C109/C109M Test Method for Compressive Strength of
mortar on a mason’s mortar board is disturbed by the activity
Hydraulic Cement Mortars (Using 2-in. or [50 mm] Cube
of the mason, samples from a mason’s mortar board shall be so
Specimens)
identified to differentiate them from samples taken from a
C128 Test Method for Relative Density (Specific Gravity)
mortar board used exclusively for test purposes.
and Absorption of Fine Aggregate
C173/C173M Test Method for Air Content of Freshly Mixed
4. Summary of Test Methods
Concrete by the Volumetric Method
4.1 Preconstruction evaluation of mortar systems involves
C185 Test Method for Air Content of Hydraulic Cement
the preparation of one or more trial batches, which are mixed
Mortar
in the laboratory using mechanical batch mixers. These trial
C187 Test Method for Amount of Water Required for Nor-
batches are sampled and used in establishing the plastic and
mal Consistency of Hydraulic Cement Paste
hardened properties of the mixtures. Because all the trial
C231/C231M Test Method for Air Content of Freshly Mixed
mixtures are prebatched by weight, additional characteristics of
Concrete by the Pressure Method
the mortars may be calculated and used in an analysis of mortar
C270 Specification for Mortar for Unit Masonry
performance.
C470/C470M Specification for Molds for Forming Concrete
4.2 During actual construction, evaluation of masonry mor-
Test Cylinders Vertically
tars is possible by sampling the mortar at various stages of
C511 Specification for Mixing Rooms, Moist Cabinets,
construction, and performing tests on both its plastic and
Moist Rooms, and Water Storage Tanks Used in the
hardened properties. The test results permit further verification
Testing of Hydraulic Cements and Concretes
of preconstruction testing, and reflect batch-to-batch variations
C617/C617M Practice for Capping Cylindrical Concrete
introduced during mortar production and use at the construc-
Specimens
tion site. More immediate corrective action for the mixing
C1093 Practice for Accreditation of Testing Agencies for
procedure is thereby attainable.
Masonry
C1180 Terminology of Mortar and Grout for Unit Masonry
4.3 The following test methods may be singly or collec-
C1231/C1231M Practice for Use of Unbonded Caps in
tively incorporated into the testing to establish mortar
Determination of Compressive Strength of Hardened Cy-
composition, and mortar plastic and hardened properties:
lindrical Concrete Specimens
4.3.1 Annex A1—Test Method for Consistency by Cone
C1324 Test Method for Examination and Analysis of Hard-
Penetration,
ened Masonry Mortar
4.3.2 Annex A2—Test Method for Consistency Retention
C1586 Guide for Quality Assurance of Mortars
(Board Life) of Mortars for Unit Masonry Using a Cone
E11 Specification for Woven Wire Test Sieve Cloth and Test
Penetrometer,
Sieves
4.3.3 Annex A3—Test Method for Initial Consistency and
Consistency Retention (Board Life) of Masonry Mortars Using
3. Terminology
a Modified Concrete Penetrometer,
4.3.4 Annex A4—Test Method for Mortar Aggregate Ratio,
3.1 Terminology defined in Terminology C1180 shall apply
4.3.5 Annex A5—Test Method for Mortar Air Content, and
for these test methods.
4.3.6 Annex A6—Test Method for Compressive Strength of
3.2 Definitions of Terms Specific to This Standard:
Molded Masonry Mortar Cylinders and Cubes.
3.2.1 disturbed sample, n—any plastic mortar test sample
5. Significance and Use
which is taken at some time after mixing and bulk sampling,
that is further remixed or molded immediately prior to test, or
5.1 During preconstruction and construction evaluations,
both.
use of these test methods establishes specific and overall
performance characteristics for the mortar system.
3.2.2 undisturbed sample, n—any plastic mortar test sample
molded immediately after mixing and sampling that sits on a
5.2 Preconstruction testing of mortars prebatched by weight
vibration-free surface until tested.
provides information for the selection of the individual mortar
system best suited for the masonry to be constructed. The
3.2.3 as-mixed samples, n—mortar samples that are ob-
recommended tests and their significance are as follows:
tained after mixing and prior to use of the mortar in construc-
5.2.1 Consistency determinations by cone penetration (An-
tion.
nex 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
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
penetration value than those measured during the preconstruc-
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
tion tests, the cone preparation test serves to standardize water
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. additions for mortars being considered as alternatives before
C780 − 23
construction. Additional testing of mortar water content- using these test methods on consecutive or intermittent batches
consistency relationships (Annex A4) will allow relating these provides a method for measurement of batch-to-batch varia-
two factors to batch-to-batch variations at the construction site. tions in the mortar production. Testing during actual construc-
tion may be referenced to laboratory testing and used to predict
5.2.2 Consistency retention by cone penetration (Annex A2)
later age mortar characteristics. In addition to the comments in
using disturbed or undisturbed mortar samples provides a
5.2, the following test meanings may be obtained from
means of establishing the early-age setting and stiffening
construction project testing:
characteristics of the mortars. Because laboratory testing is
conducted under static climatic conditions, consistency reten-
5.3.1 Consistency by cone penetration (Annex A1) is used
tion test results reflect the relative performance of the mortar
as a quick reference for indicating batch-to-batch variations in
systems under test. The same general relationships are ex-
mix ingredients and mixing time. Erratic consistency readings
pected to hold during testing at the construction project, except indicate poor control during batching and mixing, but they do
as they are influenced by jobsite weather conditions.
not indicate if cement, sand, or water additions are improper.
Other test methods must be used to isolate and identify the
5.2.3 Mortar water-content determinations (Annex A4) al-
low measurement of the water content of the mortar mixture. unsatisfactory proportioning or mixing procedure, for example,
cement to aggregate, mortar water, or air content tests.
Mortars prebatched using moist masonry sand may be math-
ematically analyzed for mortar water content; however, this
5.3.2 Consistency retention by cone penetration (Annex A2)
test, when used for preconstruction evaluation, establishes the
tests establishes the early-age setting and stiffening character-
effectiveness of the test method and serves as the control or
istics of the mortar. These properties are influenced by mix
base for tests performed at the construction site.
proportions and ingredients, weather conditions, effects of
5.2.4 Mortar aggregate ratio testing (Annex A4) provides a chemical additives, and mixing time.
method for determining the ratio of aggregate-to-cementitious
5.3.3 Individual and repeated evaluations of mortar water
materials. The sieving operation employed during this test is
content (Annex A4) show the ability of the mixer operator to
incapable of separating an individual cementitious material
properly and consistently add water to the mixer.
when more than one such material is used, but can accurately
5.3.4 Individual and repeated tests for mortar aggregate
establish the aggregate-to-cementitious materials ratio of the
ratio (Annex A4) show the ability of the mixer operator to
mixture.
properly and consistently add the cementitious material and
5.2.5 Mortar air-content testing (Annex A5) is useful in
sand to the mixer, and will establish batch-to-batch variations
establishing the value of this component of the mortar. This test
in the composition of the mortar.
is of particular importance in evaluating mortars that contain
5.3.5 Individual and repetitive tests for mortar air content
air-entraining portland cement, air-entraining lime, masonry
(Annex A5) show the changes caused by variations in mixing
cement or any combination thereof.
time, mixing efficiency and other factors.
5.2.6 Compressive strength testing (Annex A6) of molded
5.3.6 Comparison of compressive strength tests (Annex A6)
mortar cylinders and cubes establishes one of the characteris-
of field batched mortars to preconstruction mortar compression
tics of hardened mortar. Mortar compressive strength test
tests, each conducted in accordance with this test method, can
values are not representative of the actual compressive strength
be used to identify variations in mortar mix constituents and/or
of mortar in the assembly and are not appropriate for use in
proportions. Variations in compressive strength values typi-
predicting the compressive strength that would be attained by
cally indicate changes in mix water content, mixing
the mortar in the masonry assembly. The measured compres-
procedures, mix materials, material proportions, and environ-
sive strength of a molded mortar specimen is almost always
mental conditions.
lower than the strength of the same mortar in the wall,
primarily as a result of differences in mortar water content and NOTE 4—Variations in the measured compressive strengths of field-
sampled mortar and between the measured compressive strengths of
specimen shape. Mortar compressive strength is influenced by
construction and pre-construction mortar samples should be expected.
mortar water content at the time of set. Because molded mortar
Many of these variations result from sampling mortar from the mixer or
specimens are not in contact with absorptive masonry units and
mortarboard and do not necessarily translate into significant mortar
are not subjected to other mechanisms of water loss, they have
strength variations in the wall. Unit suction will remove water from the
mortar in the wall and the curing conditions are different. However,
higher water contents than mortar in the wall. Higher water
significant variation between measured compression strength values
contents almost always result in lower strengths. Specimen size
should prompt evaluation of probable causes of this variation. Conducting
and shape also affect compressive strength. Cylinders and
companion mortar aggregate ratio tests would assist in determining if
cubes exhibit different strengths even when made from the
changes in mix constituents and proportions are the likely cause. (See
same mortar mix. Both of these specimen configurations yield 5.2.6 for additional information).
lower strengths than what would be attained if a specimen
having the same size and configuration of a typical mortar joint 6. Test Methods Limitations
could be reliably tested.
6.1 During mortar aggregate ratio testing, no attempt has
NOTE 3—When cube and cylinder test specimens from like mixtures are been made to establish the proportions of either portland
to be compared, the cylinder compressive strength is approximately 85 %
cement to lime or portland cement to masonry cement in the
of the cube compressive strength.
mixture. Additional testing could establish this proportioning,
5.3 Testing during the actual construction may employ one however, batching operations should be supervised to ensure
or more of the test methods described in 4.2. Repetitive testing the correct proportioning of these ingredients.
C780 − 23
should be taken to ensure that the same sampling procedure is used when
6.2 Due to the greater ability to weigh materials accurately,
comparing test results throughout the course of a project. Unless specific
mix on a precise schedule, and control other factors relating to
time-dependent properties of the mortar are being evaluated, sampling
the production and testing of mortar under laboratory condi-
should be done in accordance with 9.3.1.
tions as compared to field conditions, the principal purpose of
9.3.1 Take as-mixed samples as follows: When mixing is
these test methods is to provide a means to identify, measure,
performed in a mixer, obtain samples either during the dis-
evaluate, and control differences that exist between laboratory
charge of the mixer or after the mortar has been discharged into
and jobsite mortars.
the mortar receptacle. If samples are taken during the discharge
6.3 Test Method C1324 is available for examination and
of the mixer, they shall be taken at any time except for the first
analysis of hardened masonry mortars. There is no ASTM
and last 10 % of the batch. Samples of the mortar taken after
method for determining compressive strength of hardened
discharge from the mixer shall be representative of the entire
mortar from samples taken from a structure.
batch. When mixing is not performed in a mixer, obtain
samples following the procedure in 9.3.
7. Apparatus
9.3.2 Take mortar for mortar board tests in accordance with
7.1 The apparatus required for these tests, along with the
9.3.1, and place upon mortar boards typical of those used or to
apparatus for sampling (see Section 9) are given in the
be used at the project. For construction site testing, expose the
individual tests included in the annexes.
test mortar on the board(s) to climatic conditions typical of
those on the jobsite. When mortar from a mason’s mortar board
8. Hazards
is used for test purposes, identify it further to reflect this
exception for proper data interpretation. Thoroughly hand-mix
8.1 During any period that the alcohol used in the mortar
aggregate ratio test is exposed to the atmosphere, and particu- mortar selected for testing with a trowel immediately before
sampling for tests or specimens. Record the lapsed time from
larly when the test sample is being dried, the tester should be
aware that alcohol is a very flammable material. Prior to drying the end of mixing as part of the test data.
9.3.3 Take retempered mortar board samples from the
the sample in an oven, place the sample in a shallow pan and
flash off the alcohol by intentional ignition in an open, mason’s mortar board at recorded time periods after mixing
and retempering. Thoroughly hand-mix all mortar on the board
well-ventilated area.
with a trowel before sampling.
9. Sampling
9.4 Time to Test:
9.1 This section deals with the sampling of individual
9.4.1 The test for cone penetration (Annex A1) shall be
mortar ingredients and of the mortar itself for preconstruction
started within five minutes after obtaining the final portion of
evaluation in the laboratory and construction evaluation at the
the sample.
jobsite.
9.4.2 The initial readings for consistency retention (Annex
A2 and Annex A3) shall be started within five minutes after
9.2 Complete the sampling of materials as follows:
obtaining the final portion of the sample.
9.2.1 Bagged material, such as portland cement, lime, and
9.4.3 The mortar samples for mortar-aggregate ratio (Annex
masonry cement, shall be of the type and brand that will be
A4) shall be introduced into the containers with alcohol within
used or is being considered for use in the actual construction.
five minutes after obtaining the final portion of the sample.
Obtain full-bag lots in sufficient quantity for completing the
9.4.4 The test for air content (Annex A5) shall be started
desired tests.
within five minutes after obtaining the final portion of the
9.2.2 Aggregate for test purposes shall be from the same
sample.
source and of the same description as will be used or is being
9.4.5 Molding of specimens for compressive strength (An-
considered for use in the actual construction. Obtain a repre-
nex A6) shall be started within 15 minutes after obtaining the
sentative sample of sufficient quantity to complete the desired
final portion of the sample.
tests.
9.2.3 Water for test purposes need not be the same as that to
9.5 Record sampling procedures to include the date, time,
be used in construction, except when it is known or suspected
place, and method of sampling. When applicable, note and
that the properties of the water available for mortar production
record the climatic conditions.
at the construction site will have a measurable effect upon the
10. Test Specimens
mortar properties. In normal testing, clean, potable water shall
be acceptable for test purposes.
10.1 During preconstruction evaluation of masonry mortars,
measure plastic mortar properties using a single test specimen
9.3 Obtain plastic mortar samples both in the laboratory and
for each part of the tests. For determining hardened mortar
at the construction project by taking uniformly distributed
properties, prepare three test specimens for each test age and
incremental samples, and mixing them to form a bulk sample
property.
from which the quantity of mortar required for a specific test or
specimen can be randomly taken. When preconstruction testing
10.2 During construction evaluation of masonry mortars,
is performed, the sampling method used in construction testing
measure plastic mortar properties using a single test specimen
shall be the same as that used during preconstruction testing.
for each part of the method of test. For determining hardened
mortar properties, prepare three test specimens for each test
NOTE 5—Many factors, including sampling, can affect the characteris-
tics of fresh mortar. Sampling should be done in a consistent manner. Care age and property.
C780 − 23
the cone penetration test versus the flow table test. The cone penetration
10.3 During actual construction evaluation of masonry
test is selected for this procedure since a flow table mounted in accordance
mortars, and when batch-to-batch variations are to be
with applicable ASTM specifications is not practically portable, and
established, sample three consecutive batches and test for
correlation between laboratory and field would be lost if one procedure
plastic and hardened properties.
used the flow table and the other the cone penetrometer.
11.2 Complete the preconstruction and construction evalu-
11. Procedure
ation in accordance with the test methods appended, Annex A1
11.1 Mortar Preparation—Prepare and mix the mortar for
– Annex A6.
preconstruction evaluation in the laboratory using the materials
(see 9.2.3, regarding water) and proportions intended for use in
12. Report
construction. Use a mechanical batch mixer similar to that
12.1 A complete report shall include the following informa-
intended for use in construction.
tion:
11.1.1 Use masonry sand in the damp, as-received
12.1.1 Name and address of the testing laboratory,
condition, and handle in such a manner as to prevent segrega-
12.1.2 Identification of the report and the date of issue,
tion. Correct the water added to the mortar as free water in
12.1.3 Name and address of the client and the identification
sands above the saturated, surface-dry condition, in accordance
of the project,
with Test Method C128. Report the total water used in the mix.
12.1.4 Description and identification of the test sample,
11.1.2 Prebatch the mortar materials, by weight, to meet the
including:
desired volume proportions.
12.1.4.1 Description of constituent mortar materials,
11.1.3 Mixing—Mix the mortar following this sequence:
12.1.4.2 Identification of mixing procedures,
11.1.3.1 For each batch, mix mortar in accordance with
12.1.4.3 For field-batched mortar, material proportions, and
mixing instructions provided. If no instructions are provided,
12.1.4.4 For preblended dry mortar materials, reference to
mix in accordance with the method below. Charge the mixer
lot number, run number, or other marking provided by the
for preconstruction evaluation tests as follows:
manufacturer.
1 3
(1) approximately ⁄2 to ⁄4 of the estimated mixing water
12.1.5 Date of receipt of the test sample,
required,
12.1.6 Date(s) of sampling and identification of sampling
(2) ⁄2 to all of the sand,
method used,
(3) all the cementitious materials and mix briefly, and
12.1.7 Date(s) of test performance,
(4) add the remainder of the sand, if any, and the balance of
12.1.8 Identification of the standard test method used and a
the mixing water required to produce the desired consistency.
notation of any known deviation from the test method,
Inasmuch as laboratory procedures permit a more rapid com-
12.1.9 Name of the person(s) accepting technical responsi-
bination of materials than is generally achieved under actual
bility for the test report,
construction conditions, time delays between the various mix-
12.1.10 Identification of subcontractor test results, if appli-
ing sequences must be made to approximate jobsite situations.
cable.
(5) Mix the mortar at normal speed for 3 to 5 min after the
12.2 A complete report shall also include the test results and
completion of the charging sequence. Mortar shall be mixed
all pertinent data relating to the conduct and conditions of the
for a minimum of one minute after subsequent water additions.
tests in the test report, as required by the applicable Annex. The
NOTE 6—For best results, mix mortar in the same way each time it is
data sheet in Appendix X1 is suggested as a general format for
sampled. Alternative mixing equipment may require shorter mixing times
the development of report forms.
than traditional paddle mixers.
11.1.3.2 Determine the cone penetration value of the mortar
13. Keywords
for preconstruction evaluation tests in accordance with Annex
13.1 aggregate ratio; air content; compressive strength;
A1.
concrete penetrometer; cone penetrometer; consistency; con-
NOTE 7—There is some disagreement regarding the relative values of sistency retention; mortar
C780 − 23
ANNEXES
(Mandatory Information)
A1. TEST METHOD FOR CONSISTENCY BY CONE PENETRATION
A1.1 Scope A1.3.2 Using the spoon, place the mortar gently into the
measure in three layers of equal volume, tamping each layer 20
A1.1.1 This test method covers a procedure for determining
times with the tamper in one complete revolution around the
the consistency of mortars for unit masonry by measuring the
inner surface of the measure. Consider one complete up-and-
penetration of a conical plunger into a mortar sample.
down motion of the tamper held in a vertical position as one
A1.2 Apparatus tamping. In tamping the first layer, do not strike the tamper
forcibly against the bottom of the measure. In tamping the
A1.2.1 Unit Measure—A cylindrical measure conforming to
second and third layers, each layer is tamped in one complete
the physical requirements of Test Method C185.
revolution (rotation) with only sufficient pressure to adequately
A1.2.2 Straightedge—A steel straightedge not less than 4 in.
fill the measure and eliminate voids within the mortar. After the
(101.6 mm) long and not less than ⁄16 in. (1.59 mm) nor more
measure has been filled and tamped in the above prescribed
than ⁄8 in. (3.2 mm) in thickness.
manner, tap the sides of the measure lightly with the side of the
A1.2.3 Tamper—In accordance with Test Method C109/
tapping stick once each at five different points at approximately
C109M. The tamping face shall be flat and at right angles to the
equal spacing around the outside of the measure in order to
length of the tamper.
preclude entrapment of extraneous air. Take care that no space
is left between the mortar and the inner surface of the measure
A1.2.4 Tapping Stick—A maple wood rod, having a diam-
5 as a result of the tamping operation. Then cut the mortar off to
eter of ⁄8 in. (15.9 mm) and a length of 6 in. (152.4 mm).
a plane surface flush with the top of the measure, by drawing
A1.2.5 Spoon, metal, kitchen-type, with the handle cut off to
the straightedge with a sawing motion across the top of the
make the overall length approximately 9 in. (228.6 mm) and
measure, making two passes over the entire surface, the second
with the bowl of the spoon being approximately 4 in. (101.6
pass being made at right angles to the first. Take care in the
mm) long, 2 ⁄2 in. (63.5 mm) in width at the widest portion, and
striking-off operation that no loose sand grains cause the
1 3
⁄2 to ⁄4 in. (12.7 to 19.05 mm) deep.
straightedge to ride above the top surface of the measure.
A1.2.6 Cone Penetrometer—A Vicat apparatus, conforming
Complete the entire operation of filling and striking off the
to the physical requirements of Test Method C187, shall be 1
measure within 1 ⁄2 min. Wipe off all mortar and water
modified to allow reading cone penetrations to a depth of
adhering to the outside of the measure.
89 mm. The frame shall be raised 2 in. (50.8 mm) to accom-
A1.3.3 Raise the penetration plunger and slide the unit
modate the unit measure and the plunger in the raised position.
measure underneath the plunger until the point of the plunger
The indicator scale shall be extended to allow measuring a full
rests on the edge of the container. Tighten the set screw just
drop of 89 mm. The plunger shall be an aluminum cone, 1 ⁄8 in.
5 enough to hold the plunger and move the indicator opposite the
(41.3 mm) in diameter by 3 ⁄8-in. (92.08-mm) long, blunted to
zero point of the scale.
a hemisphere a distance of ⁄8 in. (3.2 mm) making the overall
length 3 ⁄2 in. (88.9 mm). The base of the cone shall be drilled
A1.3.4 Center the container under the plunger and release
and tapped on the centerline for threading to a stainless steel
the plunger with a swift, definite turn of the set screw while
tube of proper size and able to slide freely in the guides of the
holding the entire apparatus firmly with the other hand.
apparatus. The weight of the tube shall be adjusted so that the
A1.3.5 Read the depth of penetration in millimetres at the
combined weight of the cone, tube and index pointer is 200 6
end of 30 seconds.
2 g.
A1.4 Report
A1.3 Procedure
A1.4.1 Report the depth of cone penetration to the nearest 1
A1.3.1 Begin filling the unit measure within five minutes of
obtaining the final portion of the sample. mm.
C780 − 23
A2. TEST METHOD FOR CONSISTENCY RETENTION (BOARD LIFE) OF MORTARS FOR UNIT MASONRY USING A
CONE PENETROMETER
A2.1 Scope Prepare one test specimen in accordance with Annex A1 for
each test age. One test container will be required for each test.
A2.1.1 This method describes a procedure for determining
Immediately after filling the test container, cover the sample
the consistency retention of mortars after various time intervals
with a cover plate and invert the entire assemblage and place
by the cone penetration test method. Both disturbed and
upon a firm, level surface. Immediately prior to testing, turn the
undisturbed sample testing are included in the method. Unless
assemblage upright and remove the cover plate. The normal
otherwise stipulated, only the disturbed sample testing will be
interval between tests is 15 min. Two options are available
required.
under this test procedure. The method given for undisturbed
A2.2 Apparatus samples in A2.3.3 minimizes, by the use of the cover plate, the
effects of surface moisture evaporation on the consistency of
A2.2.1 In addition to the apparatus required for completing
the mortar. Although a mason seldom uses a board of mortar
the cone penetration test in Annex A1, extra unit measures and
which has sat undisturbed for some time without mixing it with
glass cover plates are required when using the undisturbed
his trowel first, some mortar study programs may wish to
sample test procedure for each test time to be included in the
include determinations of these surface effects. If this is
determination of consistency retention. No additional equip-
desired, vary the procedure by not covering and not inverting
ment is necessary using the disturbed mortar sample test
the test molds for the interval between their preparation and
procedure.
testing. The test report must note the use of this alternate
procedure when it is employed.
A2.3 Procedure
A2.3.1 Begin filling the unit measure(s) within five minutes A2.3.4 Determine the penetration of the cone into the
mortar sample as described in Annex A1.
of obtaining the final portion of the sample.
A2.3.2 Disturbed Samples—When testing disturbed mortar A2.3.5 Record the first measured penetration as P .
o
samples, sample and use the mortar in filling the mortar test
A2.3.6 Except when required by another standard, repeat
container immediately prior to conducting the test. Sample the
the procedure in A2.3.4 at 15 minute intervals until the
mortar as it is discharged from the mixer, and place on a mortar
measured penetration is less than 70 % of P . See Note A2.1.
o
board reserved for test purposes. This mortar shall not be used
NOTE A2.1—Some specifications and test methods may reference the
by the mason, or disturbed until immediately prior to testing.
consistency by cone penetration test and provide reading intervals and test
Just before the test, remix the mortar sample with a trowel until
duration. When this information is provided in the standard that references
it is of uniform consistency. Then agitate or handle the mortar
ASTM C780, those test details should be used.
just enough to allow proper consolidation of the mortar in the
A2.4 Report
test container. After the mortar sample has been consolidated in
the mold as described in Annex A1, immediately complete the
A2.4.1 The report shall include the following:
test. The normal interval between tests is 15 min.
A2.4.1.1 Depth of penetration to the nearest 1 mm,
A2.3.3 Undisturbed Samples—When testing undisturbed A2.4.1.2 Notation as to whether the data refers to disturbed
mortar samples, prepare the test specimens for all test ages or undisturbed samples, and
immediately after the mortar is discharged from the mixer. A2.4.1.3 Test time.
A3. TEST METHOD FOR INITIAL CONSISTENCY AND CONSISTENCY RETENTION (BOARD LIFE) OF MASONRY MOR-
TARS USING A MODIFIED CONCRETE PENETROMETER
A3.1 Scope A3.2.1.1 board life—the time period during which penetra-
tion resistance stays below a given value (P ).
A3.1.1 This method allows determination of initial consis- f
A3.2.1.2 P —the initial penetration resistance or consis-
tency and board life of masonry mortars. The method is
o
sufficiently restrictive to be used as a basis for acceptance of tency of a masonry mortar as measured, using this method.
mortars. Results correspond to pounds per square inch of
A3.2.1.3 P —the penetration resistance or consistency of a
f
pressure required to penetrate a sample of mortar 1 in. with a
masonry mortar when the mortar is too stiff for use.
disk of a given size and weight. English units of measure will
A3.2.1.4 rate of stiffening—the ratio of the difference be-
be used throughout the method.
tween P and P per time interval.
o f
A3.2 Terminology
A3.2.1.5 T —the time when the initial penetration resis-
o
tance measurement was made.
A3.2.1 Definitions:
C780 − 23
A3.2.1.6 T —the time when P was reached, obtained by for three seconds. Read and record penetrometer scale pres-
f f
interpolation. sure. Repeat applications of downward force in increments of
1 lb from 1 to 30 lb and record each incremental penetrometer
A3.3 Significance and Use
scale reading. Divide the total applied load plus the weight of
the penetrometer by the cross sectional area of the disk. These
A3.3.1 Data obtained from this method are used to deter-
values represent pressure at the face of disk. Prepare a
mine consistency of a mortar, as well as board life of a mortar.
calibration chart to allow converting penetrometer scale read-
The method is also useful for determining when a mortar is or
ing to penetration resistance, in psi. See Table A3.1.
is not acceptable for use due to stiffness. When penetration
resistance is outside the desired range (P to P ) the mortar is
o f
A3.7 Procedure
retempered or discarded.
A3.7.1 Mortar to be tested for board life shall be prepared so
A3.4 Apparatus
the initial penetration resistance (P ) is either 0.94 6 0.05 psi
o
for mortar to be used with brick sized units or 1.24 6 0.05 psi
A3.4.1 Concrete Penetrometer, spring activated with cali-
for mortar to be used with heavier units requiring less plastic
bration markings from 20 to 700 psi. The penetrometer shall be
mortars for proper bedment. Water additions to the mortar
modified as required by A3.4.1.1. The modification of the
decrease penetration resistance. Prepare comparison mortars
penetrometer prevents direct use of the scale on the penetrom-
with varied composition and proportions controlling equip-
eter. Therefore, the penetrometer shall be calibrated in accor-
ment and procedures.
dance with A3.6.
A3.4.1.1 Disk Modification—The penetrometer shall be
A3.7.2 Begin filling the circular ring within five minutes of
modified by securely attaching a disk perpendicular to the
obtaining the final portion of the sample.
bottom of the penetrometer shaft. The disk shall be 1 6 ⁄16 in.
A3.7.3 Place the mortar in the circular ring, previously
thick with a diameter of 2.65 to 3.05 in. The disk material shall
centered on the damp mortar board. Spade the mortar with the
be rigid and non-absorbent. See Note A3.1.
square-nosed shovel. Screed the top surface of the specimen to
NOTE A3.1—Pocket-sized concrete penetrometers are available in the surface of the ring using either the straightedge or trowel.
different configurations. Satisfactory results have been achieved with a
Remove mold within three min after mortar mixing was
disk made of either (1) machined steel secured to the penetrometer shaft
with a retaining sleeve and thumbscrew, or (2) vulcanized rubber (such as
a regulation National Hockey League puck) secured to the penetrometer
shaft by epoxying the shaft to a hole drilled into the center of the disk. TABLE A3.1 Penetrometer Calibration
Other materials and securing methods can be used as long as they meet the (5.67 in. Disk, 2.47 lb of Penetrometer and Disk)
requirements of A3.4.1.1. It is recommended that the disk also be abrasion
NOTE 1—The pressure exerted on the specimen is the measured weight
resistant and resistant to chemical attack by mortar.
plus the weight of the penetrometer and disk divided by the area of the
A3.4.2 Trowel—A mason’s trowel. disk. For example, the disk weighs 2.47 lb and the area of the disk is
5.67 in. ; 1 lb of measured weight + 2.47 lb weight of penetrometer and
A3.4.3 Shovel—A square nosed shovel. 2
disk (tare)/5.67 in. = 0.61 psi.
A3.4.4 Ring—A 16-in. inside diameter ring made of steel or Measured Weight, lb Scale Readings psi
other rigid, chemical and abrasive resistant material, 3 in. high 1 20 0.61
2 40 0.79
with exterior, opposing handles.
3 60 0.96
4 80 1.14
A3.4.5 Mortar Board—A nominal 2 ft by 2 ft by ⁄4 in.
5 100 1.32
mortar board of exterior grade plywood.
6 120 1.49
7 140 1.67
A3.4.6 Straightedge—A wooden straightedge of nominal
8 160 1.85
dimensions, 2 in. by 4 in. and 24 in. in length (optional).
9 180 2.02
10 200 2.20
A3.5 Sampling, Test Specimens, and Test Units 11 220 2.38
12 240 2.55
A3.5.1 At least one specimen shall be prepared for each
13 260 2.73
14 280 2.90
mortar.
15 300 3.08
16 320 3.26
A3.5.2 Test condition shall be either actual climatic condi-
17 340 3.43
tions and construction practices at the construction site or
18 360 3.61
simulated conditions considering temperature, humidity, wind,
19 380 3.79
20 400 3.96
sand, water, mixing equipment, handling, mixing procedure,
21 420 4.14
etc.
22 440 4.32
23 460 4.49
A3.6 Calibration and Standardization
24 480 4.67
25 500 4.84
A3.6.1 Calibrate the penetrometer by placing it on a weigh
26 520 5.02
scale with a capacity of 30 lb and accurate to 0.05 lb. Place the 27 540 5.20
28 560 5.37
penetrometer on the weigh scale platform and tare to zero.
29 580 5.55
Push downward on the handhold of the penetrometer until the
30 600 5.73
weigh scale registers 1 lb. This pressure shall be applied within
C780 − 23
completed. Immediately take three penetration readings. Posi- Rate of stiffening 5 P 2 P /T , psi permin (A3.1)
~ !
f o f
tion the disk of the penetrometer on the surface of the mortar
where:
at least one disk diameter from both the edge and previous test
P and P are as indicated:
f o
areas. Apply uniform pressure within three seconds so the disk
A
Mortar for Brick Sized Units Mortar for Heavier Units
penetrates the mortar a distance of 1 in., the disk thickness.
P = 1.74 P = 2.44
f f
Read the penetrometer scale to the nearest 5 psi and record P = 0.94 P = 1.24
o o
—————
penetrometer scale reading and time of readings. Reset scale
marker to zero. Average the three readings and convert to
A
The size, weight and bedding area of the unit should be considered in selecting
applied pressure, in psi, using the calibration curve. Record this
the appropriate values of P and P .
f o
result as P , psi, and the time as T , min.
o o
T 5 interpolated time when P obtained. (A3.2)
f f
A3.7.4 Within two minutes after completing the three initial
(see Note A3.3)
penetration readings, thoroughly remix the mortar using ma-
NOTE A3.3—For graphic illustration, see Fig. A3.1.
son’s trowel. Position ring, screed, and remove ring. Allow
A3.8.2 Report T as board life, in minutes. P is approxi-
f f
mortar to remain undisturbed for 15 min since T . Read and
o
mately equal to the consistency when mortars are judged too
record three additional penetrations and time, using the proce-
stiff to be used properly.
dures of A3.7.3. Repeat this procedure every 15 min till the
average penetration resistance is either 1.74 psi for mortars to A3.8.3 Report all penetration resistance data in psi and
be used with brick sized units or 2.44 psi for mortars to be used associated times in minutes.
with heavier units. (Note A3.2)
A3.9 Precision and Bias
NOTE A3.2—Uniformly spaced measurements other than 15 min may
A3.9.1 The precision of the procedure in Test Method C780,
be desirable for research and other testing needs.
Annex A3, for measuring consistency and board life is being
A3.8 Report
determined.
A3.8.1 Report the following information: A3.9.2 The procedure in Test Method C780, Annex A3, for
A3.8.1.1 Plot data of penetration resistance, in psi, with measuring the consistency and board life of masonry mortars
elapsed time until P is reached. has no bias because the value of consistency and board life can
f
A3.8.1.2 Calculate and report the rate of stiffening as: be defined only in terms of a test method.
FIG. A3.1 Penetration Resistance Versus Elapsed Time
C780 − 23
A4. TEST METHOD FOR MORTAR AGGREGATE RATIO
A4.1 Scope A4.3.2 Use as-mixed samples for this test. Introduce the
mortar samples into the sample containers within five minutes
A4.1.1 This test method describes a procedure for determin-
of obtaining the final portion of the sample.
ing the aggregate-to-cementitious materials ratio of mortars for
unit masonry by determining the mortar fraction coarser than a A4.3.3 At the construction site, place 1.1 to 1.2 lb (500 to
150-μm (No. 100) sieve and correcting for the sand finer than 550 g) of mortar into each mortar sample container with the
the 150-μm (No. 100) sieve. This test method also includes a alcohol, as rapidly as is practical.
...

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 − 20 C780 − 23
Standard Test MethodMethods 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 procedureThese test methods provide standard procedures 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 coversThese test methods cover 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 methodthese test methods and Specification
C270.
NOTE 2—The testing agency performing this test methodthese test methods should be evaluated in accordance with Practice C1093.
1.2 Preconstruction Evaluation—This test method permitsThese test methods permit comparisons of mortars made from different
materials under simulated field conditions. It isThey are also used to establish baseline values for comparative evaluation of field
mortars.
1.3 Construction Evaluation—Use of this methodthese methods in the field providesprovide a means for quality assurance of
field-mixed mortar. It includesThey include 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.
This test method isThese test methods are under the jurisdiction of ASTM Committee C12 on Mortars and Grouts for Unit Masonry and isare the direct responsibility
of Subcommittee C12.02 on Research and Methods of Test.
Current edition approved June 15, 2020July 1, 2023. Published July 2020July 2023. Originally approved in 1974. Last previous edition approved in 20192020 as
C780 – 19.C780 – 20. DOI: 10.1520/C0780-20.10.1520/C0780-23.
*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 − 23
1.4 The test results obtained under this test methodthese test methods 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 The text of this standard references notes and footnotes that provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of the standard.
1.7 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. For specific hazards statements, see Section 8.
1.8 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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 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/C231M 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/C617M 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/C1231M Practice for Use of Unbonded Caps in Determination of Compressive Strength of Hardened Cylindrical
Concrete Specimens
C1324 Test Method for Examination and Analysis of Hardened Masonry Mortar
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.these test methods.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 disturbed sample, n—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.
3.2.2 undisturbed sample, n—any plastic mortar test sample molded immediately after mixing and sampling that sits on a
vibration-free surface until tested.
3.2.3 as-mixed samples, n—mortar samples that are obtained after mixing and prior to use of the mortar in construction.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
C780 − 23
3.2.4 mortar board samples, n—mortar samples that are obtained from the mortar board after some established time period from
the end of mixing, and before retempering.
3.2.4.1 Discussion—
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 MethodMethods
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—Test Method for Consistency by Cone Penetration,
4.3.2 Annex A2—Test Method for Consistency Retention (Board Life) of Mortars for Unit Masonry Using a Cone Penetrometer,
4.3.3 Annex A3—Test Method for Initial Consistency and Consistency Retention (Board Life) of Masonry Mortars Using a
Modified Concrete Penetrometer,
4.3.4 Annex A4—Test Method for Mortar Aggregate Ratio,
4.3.5 Annex A5—Test Method for Mortar Air Content, and
4.3.6 Annex A6—Test Method for Compressive Strength of Molded Masonry Mortar Cylinders and Cubes.
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
C780 − 23
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.
5.3.6 Comparison of compressive strength tests (Annex A6) of field batched mortars to preconstruction mortar compression tests,
each conducted in accordance with this test method, can be used to identify variations in mortar mix constituents and/or
proportions. Variations in compressive strength values typically indicate changes in mix water content, mixing procedures, mix
materials, material proportions, and environmental conditions.
NOTE 4—Variations in the measured compressive strengths of field-sampled mortar and between the measured compressive strengths of construction and
pre-construction mortar samples should be expected. Many of these variations result from sampling mortar from the mixer or mortarboard and do not
C780 − 23
necessarily translate into significant mortar strength variations in the wall. Unit suction will remove water from the mortar in the wall and the curing
conditions are different. However, significant variation between measured compression strength values should prompt evaluation of probable causes of
this variation. Conducting companion mortar aggregate ratio tests would assist in determining if changes in mix constituents and proportions are the likely
cause. (See 5.2.6 for additional information).
6. Test MethodMethods Limitations
6.1 During mortar aggregate ratio testing, no attempt has been made to establish the proportions of either portland cement to lime
or portland cement to masonry cement in the mixture. Additional testing could establish this proportioning, however, batching
operations should be supervised to ensure the correct proportioning of these ingredients.
6.2 Due to the greater ability to weigh materials accurately, mix on a precise schedule, and control other factors relating to the
production and testing of mortar under laboratory conditions as compared to field conditions, the principal purpose of this test
methodthese test methods is to provide a means to identify, measure, evaluate, and control differences that exist between laboratory
and jobsite mortars.
6.3 Test Method C1324 is available for examination and analysis of hardened masonry mortars. There is no ASTM method for
determining compressive strength of hardened mortar from samples taken from a structure.
7. Apparatus
7.1 The apparatus required for this test,these tests, along with the apparatus for sampling (see Section 9) are given in the individual
tests included in the annexes.
8. Hazards
8.1 During any period that the alcohol used in the mortar aggregate ratio test is exposed to the atmosphere, and particularly when
the test sample is being dried, the tester should be aware that alcohol is a very flammable material. Prior to drying the sample in
an oven, place the sample in a shallow pan and flash off the alcohol by intentional ignition in an open, well-ventilated area.
9. Sampling
9.1 This section deals with the sampling of individual mortar ingredients and of the mortar itself for preconstruction evaluation
in the laboratory and construction evaluation at the jobsite.
9.2 Complete the sampling of materials as follows:
9.2.1 Bagged material, such as portland cement, lime, and masonry cement, shall be of the type and brand that will be used or
is being considered for use in the actual construction. Obtain full-bag lots in sufficient quantity for completing the desired tests.
9.2.2 Aggregate for test purposes shall be from the same source and of the same description as will be used or is being considered
for use in the actual construction. Obtain a representative sample of sufficient quantity to complete the desired tests.
9.2.3 Water for test purposes need not be the same as that to be used in construction, except when it is known or suspected that
the properties of the water available for mortar production at the construction site will have a measurable effect upon the mortar
properties. In normal testing, clean, potable water shall be acceptable for test purposes.
9.3 Obtain plastic mortar samples both in the laboratory and at the construction project by taking uniformly distributed incremental
samples, and mixing them to form a bulk sample from which the quantity of mortar required for a specific test or specimen can
be randomly taken. When preconstruction testing is performed, the sampling method used in construction testing shall be the same
as that used during preconstruction testing.
NOTE 5—Many factors, including sampling, can affect the characteristics of fresh mortar. Sampling should be done in a consistent manner. Care should
be taken to ensure that the same sampling procedure is used when comparing test results throughout the course of a project. Unless specific
time-dependent properties of the mortar are being evaluated, sampling should be done in accordance with 9.3.1.
9.3.1 Take as-mixed samples as follows: When mixing is performed in a mixer, obtain samples either during the discharge of the
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mixer or after the mortar has been discharged into the mortar receptacle. If samples are taken during the discharge of the mixer,
they shall be taken at any time except for the first and last 10 % of the batch. Samples of the mortar taken after discharge from
the mixer shall be representative of the entire batch. When mixing is not performed in a mixer, obtain samples following the
procedure in 9.3.
9.3.2 Take mortar for mortar board tests in accordance with 9.3.1, and place upon mortar boards typical of those used or to be
used at the project. For construction site testing, expose the test mortar on the board(s) to climatic conditions typical of those on
the jobsite. When mortar from a mason’s mortar board is used for test purposes, identify it further to reflect this exception for
proper data interpretation. Thoroughly hand-mix mortar selected for testing with a trowel immediately before sampling for tests
or specimens. Record the lapsed time from the end of mixing as part of the test data.
9.3.3 Take retempered mortar board samples from the mason’s mortar board at recorded time periods after mixing and
retempering. Thoroughly hand-mix all mortar on the board with a trowel before sampling.
9.4 Time to Test:
9.4.1 The test for cone penetration (Annex A1) shall be started within five minutes after obtaining the final portion of the sample.
9.4.2 The initial readings for consistency retention (Annex A2 and Annex A3) shall be started within five minutes after obtaining
the final portion of the sample.
9.4.3 The mortar samples for mortar-aggregate ratio (Annex A4) shall be introduced into the containers with alcohol within five
minutes after obtaining the final portion of the sample.
9.4.4 The test for air content (Annex A5) shall be started within five minutes after obtaining the final portion of the sample.
9.4.5 Molding of specimens for compressive strength (Annex A6) shall be started within 15 minutes after obtaining the final
portion of the sample.
9.5 Record sampling procedures to include the date, time, place, and method of sampling. When applicable, note and record the
climatic conditions.
10. Test Specimens
10.1 During preconstruction evaluation of masonry mortars, measure plastic mortar properties using a single test specimen for
each part of the tests. For determining hardened mortar properties, prepare three test specimens for each test age and property.
10.2 During construction evaluation of masonry mortars, measure plastic mortar properties using a single test specimen for each
part of the method of test. For determining hardened mortar properties, prepare three test specimens for each test age and property.
10.3 During actual construction evaluation of masonry mortars, and when batch-to-batch variations are to be established, sample
three consecutive batches and test for plastic and hardened properties.
11. Procedure
11.1 Mortar Preparation—Prepare and mix the mortar for preconstruction evaluation in the laboratory using the materials (see
9.2.3, regarding water) and proportions intended for use in construction. Use a mechanical batch mixer similar to that intended for
use in construction.
11.1.1 Use masonry sand in the damp, as-received condition, and handle in such a manner as to prevent segregation. Correct the
water added to the mortar as free water in sands above the saturated, surface-dry condition, in accordance with Test Method C128.
Report the total water used in the mix.
11.1.2 Prebatch the mortar materials, by weight, to meet the desired volume proportions.
11.1.3 Mixing—Mix the mortar following this sequence:
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11.1.3.1 For each batch, mix mortar in accordance with mixing instructions provided. If no instructions are provided, mix in
accordance with the method below. Charge the mixer for preconstruction evaluation tests as follows:
1 3
(1) approximately ⁄2 to ⁄4 of the estimated mixing water required,
(2) ⁄2 to all of the sand,
(3) all the cementitious materials and mix briefly, and
(4) add the remainder of the sand, if any, and the balance of the mixing water required to produce the desired consistency.
Inasmuch as laboratory procedures permit a more rapid combination of materials than is generally achieved under actual
construction conditions, time delays between the various mixing sequences must be made to approximate jobsite situations.
(5) Mix the mortar at normal speed for 3 to 5 min after the completion of the charging sequence. Mortar shall be mixed for
a minimum of one minute after subsequent water additions.
NOTE 6—For best results, mix mortar in the same way each time it is sampled. Alternative mixing equipment may require shorter mixing times than
traditional paddle mixers.
11.1.3.2 Determine the cone penetration value of the mortar for preconstruction evaluation tests in accordance with Annex A1.
NOTE 7—There is some disagreement regarding the relative values of the cone penetration test versus the flow table test. The cone penetration test is
selected for this procedure since a flow table mounted in accordance with applicable ASTM specifications is not practically portable, and correlation
between laboratory and field would be lost if one procedure used the flow table and the other the cone penetrometer.
11.2 Complete the preconstruction and construction evaluation in accordance with the test methods appended, Annex A1 – Annex
A6.
12. Report
12.1 A complete report shall include the following information:
12.1.1 Name and address of the testing laboratory,
12.1.2 Identification of the report and the date of issue,
12.1.3 Name and address of the client and the identification of the project,
12.1.4 Description and identification of the test sample, including:
12.1.4.1 Description of constituent mortar materials,
12.1.4.2 Identification of mixing procedures,
12.1.4.3 For field-batched mortar, material proportions, and
12.1.4.4 For preblended dry mortar materials, reference to lot number, run number, or other marking provided by the manufacturer.
12.1.5 Date of receipt of the test sample,
12.1.6 Date(s) of sampling and identification of sampling method used,
12.1.7 Date(s) of test performance,
12.1.8 Identification of the standard test method used and a notation of any known deviation from the test method,
12.1.9 Name of the person(s) accepting technical responsibility for the test report,
12.1.10 Identification of subcontractor test results, if applicable.
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12.2 A complete report shall also include the test results and all pertinent data relating to the conduct and conditions of the tests
in the test report, as required by the applicable Annex. The data sheet in Appendix X1 is suggested as a general format for the
development of report forms.
13. Keywords
13.1 aggregate ratio; air content; compressive strength; concrete penetrometer; cone penetrometer; consistency; consistency
retention; mortar
ANNEXES
(Mandatory Information)
A1. TEST METHOD FOR CONSISTENCY BY CONE PENETRATION
A1.1 Scope
A1.1.1 This test method covers a procedure for determining the consistency of mortars for unit masonry by measuring the
penetration of a conical plunger into a mortar sample.
A1.2 Apparatus
A1.2.1 Unit Measure—A cylindrical measure conforming to the physical requirements of Test Method C185.
A1.2.2 Straightedge—A steel straightedge not less than 4 in. (101.6 mm) long and not less than ⁄16 in. (1.59 mm) nor more than
⁄8 in. (3.2 mm) in thickness.
A1.2.3 Tamper—In accordance with Test Method C109/C109M. The tamping face shall be flat and at right angles to the length
of the tamper.
A1.2.4 Tapping Stick—A maple wood rod, having a diameter of ⁄8 in. (15.9 mm) and a length of 6 in. (152.4 mm).
A1.2.5 Spoon, metal, kitchen-type, with the handle cut off to make the overall length approximately 9 in. (228.6 mm) and with
1 1 3
the bowl of the spoon being approximately 4 in. (101.6 mm) long, 2 ⁄2 in. (63.5 mm) in width at the widest portion, and ⁄2 to ⁄4
in. (12.7 to 19.05 mm) deep.
A1.2.6 Cone Penetrometer—A Vicat apparatus, conforming to the physical requirements of Test Method C187, shall be modified
to allow reading cone penetrations to a depth of 89 mm. The frame shall be raised 2 in. (50.8 mm) to accommodate the unit measure
and the plunger in the raised position. The indicator scale shall be extended to allow measuring a full drop of 89 mm. The plunger
5 5 1
shall be an aluminum cone, 1 ⁄8 in. (41.3 mm) in diameter by 3 ⁄8-in. (92.08-mm) long, blunted to a hemisphere a distance of ⁄8
in. (3.2 mm) making the overall length 3 ⁄2 in. (88.9 mm). The base of the cone shall be drilled and tapped on the centerline for
threading to a stainless steel tube of proper size and able to slide freely in the guides of the apparatus. The weight of the tube shall
be adjusted so that the combined weight of the cone, tube and index pointer is 200 6 2 g.
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A1.3 Procedure
A1.3.1 Begin filling the unit measure within five minutes of obtaining the final portion of the sample.
A1.3.2 Using the spoon, place the mortar gently into the measure in three layers of equal volume, tamping each layer 20 times
with the tamper in one complete revolution around the inner surface of the measure. Consider one complete up-and-down motion
of the tamper held in a vertical position as one tamping. In tamping the first layer, do not strike the tamper forcibly against the
bottom of the measure. In tamping the second and third layers, each layer is tamped in one complete revolution (rotation) with
only sufficient pressure to adequately fill the measure and eliminate voids within the mortar. After the measure has been filled and
tamped in the above prescribed manner, tap the sides of the measure lightly with the side of the tapping stick once each at five
different points at approximately equal spacing around the outside of the measure in order to preclude entrapment of extraneous
air. Take care that no space is left between the mortar and the inner surface of the measure as a result of the tamping operation.
Then cut the mortar off to a plane surface flush with the top of the measure, by drawing the straightedge with a sawing motion
across the top of the measure, making two passes over the entire surface, the second pass being made at right angles to the first.
Take care in the striking-off operation that no loose sand grains cause the straightedge to ride above the top surface of the measure.
Complete the entire operation of filling and striking off the measure within 1 ⁄2 min. Wipe off all mortar and water adhering to the
outside of the measure.
A1.3.3 Raise the penetration plunger and slide the unit measure underneath the plunger until the point of the plunger rests on the
edge of the container. Tighten the set screw just enough to hold the plunger and move the indicator opposite the zero point of the
scale.
A1.3.4 Center the container under the plunger and release the plunger with a swift, definite turn of the set screw while holding
the entire apparatus firmly with the other hand.
A1.3.5 Read the depth of penetration in millimetres at the end of 30 seconds.
A1.4 Report
A1.4.1 Report the depth of cone penetration to the nearest 1 mm.
A2. TEST METHOD FOR CONSISTENCY RETENTION (BOARD LIFE) OF MORTARS FOR UNIT MASONRY USING A
CONE PENETROMETER
A2.1 Scope
A2.1.1 This method describes a procedure for determining the consistency retention of mortars after various time intervals by the
cone penetration test method. Both disturbed and undisturbed sample testing are included in the method. Unless otherwise
stipulated, only the disturbed sample testing will be required.
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A2.2 Apparatus
A2.2.1 In addition to the apparatus required for completing the cone penetration test in Annex A1, extra unit measures and glass
cover plates are required when using the undisturbed sample test procedure for each test time to be included in the determination
of consistency retention. No additional equipment is necessary using the disturbed mortar sample test procedure.
A2.3 Procedure
A2.3.1 Begin filling the unit measure(s) within five minutes of obtaining the final portion of the sample.
A2.3.2 Disturbed Samples—When testing disturbed mortar samples, sample and use the mortar in filling the mortar test container
immediately prior to conducting the test. Sample the mortar as it is discharged from the mixer, and place on a mortar board reserved
for test purposes. This mortar shall not be used by the mason, or disturbed until immediately prior to testing. Just before the test,
remix the mortar sample with a trowel until it is of uniform consistency. Then agitate or handle the mortar just enough to allow
proper consolidation of the mortar in the test container. After the mortar sample has been consolidated in the mold as described
in Annex A1, immediately complete the test. The normal interval between tests is 15 min.
A2.3.3 Undisturbed Samples—When testing undisturbed mortar samples, prepare the test specimens for all test ages immediately
after the mortar is discharged from the mixer. Prepare one test specimen in accordance with Annex A1 for each test age. One test
container will be required for each test. Immediately after filling the test container, cover the sample with a cover plate and invert
the entire assemblage and place upon a firm, level surface. Immediately prior to testing, turn the assemblage upright and remove
the cover plate. The normal interval between tests is 15 min. Two options are available under this test procedure. The method given
for undisturbed samples in A2.3.3 minimizes, by the use of the cover plate, the effects of surface moisture evaporation on the
consistency of the mortar. Although a mason seldom uses a board of mortar which has sat undisturbed for some time without
mixing it with his trowel first, some mortar study programs may wish to include determinations of these surface effects. If this is
desired, vary the procedure by not covering and not inverting the test molds for the interval between their preparation and testing.
The test report must note the use of this alternate procedure when it is employed.
A2.3.4 Determine the penetration of the cone into the mortar sample as described in Annex A1.
A2.3.5 Record the first measured penetration as P .
o
A2.3.6 Except when required by another standard, repeat the procedure in A2.3.4 at 15 minute intervals until the measured
penetration is less than 70 % of P . See Note A2.1.
o
NOTE A2.1—Some specifications and test methods may reference the consistency by cone penetration test and provide reading intervals and test duration.
When this information is provided in the standard that references ASTM C780, those test details should be used.
A2.4 Report
A2.4.1 The report shall include the following:
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A2.4.1.1 Depth of penetration to the nearest 1 mm,
A2.4.1.2 Notation as to whether the data refers to disturbed or undisturbed samples, and
A2.4.1.3 Test time.
A3. TEST METHOD FOR INITIAL CONSISTENCY AND CONSISTENCY RETENTION (BOARD LIFE) OF MASONRY MOR-
TARS USING A MODIFIED CONCRETE PENETROMETER
A3.1 Scope
A3.1.1 This method allows determination of initial consistency and board life of masonry mortars. The method is sufficiently
restrictive to be used as a basis for acceptance of mortars. Results correspond to pounds per square inch of pressure required to
penetrate a sample of mortar 1 in. with a disk of a given size and weight. English units of measure will be used throughout the
method.
A3.2 Terminology
A3.2.1 Definitions:
A3.2.1.1 board life—the time period during which penetration resistance stays below a given value (P ).
f
A3.2.1.2 P —the initial penetration resistance or consistency of a masonry mortar as measured, using this method.
o
A3.2.1.3 P —the penetration resistance or consistency of a masonry mortar when the mortar is too stiff for use.
f
A3.2.1.4 rate of stiffening—the ratio of the difference between P and P per time interval.
o f
A3.2.1.5 T —the time when the initial penetration resistance measurement was made.
o
A3.2.1.6 T —the time when P was reached, obtained by interpolation.
f f
A3.3 Significance and Use
A3.3.1 Data obtained from this method are used to determine consistency of a mortar, as well as board life of a mortar. The method
is also useful for determining when a mortar is or is not acceptable for use due to stiffness. When penetration resistance is outside
the desired range (P to P ) the mortar is retempered or discarded.
o f
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A3.4 Apparatus
A3.4.1 Concrete Penetrometer, spring activated with calibration markings from 20 to 700 psi. The penetrometer shall be modified
as required by A3.4.1.1. The modification of the penetrometer prevents direct use of the scale on the penetrometer. Therefore, the
penetrometer shall be calibrated in accordance with A3.6.
A3.4.1.1 Disk Modification—The penetrometer shall be modified by securely attaching a disk perpendicular to the bottom of the
penetrometer shaft. The disk shall be 1 6 ⁄16 in. thick with a diameter of 2.65 to 3.05 in. The disk material shall be rigid and
non-absorbent. See Note A3.1.
NOTE A3.1—Pocket-sized concrete penetrometers are available in different configurations. Satisfactory results have been achieved with a disk made of
either (1) machined steel secured to the penetrometer shaft with a retaining sleeve and thumbscrew, or (2) vulcanized rubber (such as a regulation National
Hockey League puck) secured to the penetrometer shaft by epoxying the shaft to a hole drilled into the center of the disk. Other materials and securing
methods can be used as long as they meet the requirements of A3.4.1.1. It is recommended that the disk also be abrasion resistant and resistant to chemical
attack by mortar.
A3.4.2 Trowel—A mason’s trowel.
A3.4.3 Shovel—A square nosed shovel.
A3.4.4 Ring—A 16-in. inside diameter ring made of steel or other rigid, chemical and abrasive resistant material, 3 in. high with
exterior, opposing handles.
A3.4.5 Mortar Board—A nominal 2 ft by 2 ft by ⁄4 in. mortar board of exterior grade plywood.
A3.4.6 Straightedge—A wooden straightedge of nominal dimensions, 2 in. by 4 in. and 24 in. in length (optional).
A3.5 Sampling, Test Specimens, and Test Units
A3.5.1 At least one specimen shall be prepared for each mortar.
A3.5.2 Test condition shall be either actual climatic conditions and construction practices at the construction site or simulated
conditions considering temperature, humidity, wind, sand, water, mixing equipment, handling, mixing procedure, etc.
A3.6 Calibration and Standardization
A3.6.1 Calibrate the penetrometer by placing it on a weigh scale with a capacity of 30 lb and accurate to 0.05 lb. Place the
penetrometer on the weigh scale platform and tare to zero. Push downward on the handhold of the penetrometer until the weigh
scale registers 1 lb. This pressure shall be applied within for three seconds. Read and record penetrometer scale pressure. Repeat
C780 − 23
applications of downward force in increments of 1 lb from 1 to 30 lb and record each incremental penetrometer scale reading.
Divide the total applied load plus the weight of the penetrometer by the cross sectional area of the disk. These values represent
pressure at the face of disk. Prepare a calibration chart to allow converting penetrometer scale reading to penetration resistance,
in psi. See Table A3.1.
A3.7 Procedure
A3.7.1 Mortar to be tested for board life shall be prepared so the initial penetration resistance (P ) is either 0.94 6 0.05 psi for
o
mortar to be used with brick sized units or 1.24 6 0.05 psi for mortar to be used with heavier units requiring less plastic mortars
for proper bedment. Water additions to the mortar decrease penetration resistance. Prepare comparison mortars with varied
composition and proportions controlling equipment and procedures.
A3.7.2 Begin filling the circular ring within five minutes of obtaining the final portion of the sample.
A3.7.3 Place the mortar in the circular ring, previously centered on the damp mortar board. Spade the mortar with the
square-nosed shovel. Screed the top surface of the specimen to the surface of the ring using either the straightedge or trowel.
Remove mold within three min after mortar mixing was completed. Immediately take three penetration readings. Position the disk
of the penetrometer on the surface of the mortar at least one disk diameter from both the edge and previous test areas. Apply
uniform pressure within three seconds so the disk penetrates the mortar a distance of 1 in., the disk thickness. Read the
TABLE A3.1 Penetrometer Calibration
(5.67 in. Disk, 2.47 lb of Penetrometer and Disk)
NOTE 1—The pressure exerted on the specimen is the measured weight
plus the weight of the penetrometer and disk divided by the area of the
disk. For example, the disk weighs 2.47 lb and the area of the disk is
5.67 in. ; 1 lb of measured weight + 2.47 lb weight of penetrometer and
disk (tare)/5.67 in. = 0.61 psi.
Measured Weight, lb Scale Readings psi
1 20 0.61
2 40 0.79
3 60 0.96
4 80 1.14
5 100 1.32
6 120 1.49
7 140 1.67
8 160 1.85
9 180 2.02
10 200 2.20
11 220 2.38
12 240 2.55
13 260 2.73
14 280 2.90
15 300 3.08
16 320 3.26
17 340 3.43
18 360 3.61
19 380 3.79
20 400 3.96
21 420 4.14
22 440 4.32
23 460 4.49
24 480 4.67
25 500 4.84
26 520 5.02
27 540 5.20
28 560 5.37
29 580 5.55
30 600 5.73
C780 − 23
penetrometer scale to the nearest 5 psi and record penetrometer scale reading and time of readings. Reset scale marker to zero.
Average the three readings and convert to applied pressure, in psi, using the calibration curve. Record this result as P , psi, and
o
the time as T , min.
o
A3.7.4 Within two minutes after completing the three initial penetration readings, thoroughly remix the mortar using mason’s
trowel. Position ring, screed, and remove ring. Allow mortar to remain undisturbed for 15 min since T . Read and record three
o
additional penetrations and time, using the procedures of A3.7.3. Repeat this procedure every 15 min till the average penetration
resistance is either 1.74 psi for mortars to be used with brick sized units or 2.44 psi for mortars to be used with heavier units. (Note
A3.2)
NOTE A3.2—Uniformly spaced measurements other than 15 min may be desirable for research and other testing needs.
A3.8 Report
A3.8.1 Report the following information:
A3.8.1.1 Plot data of penetration resistance, in psi, with elapsed time until P is reached.
f
A3.8.1.2 Calculate and report the rate of stiffening as:
Rate of stiffening 5 P 2 P /T , psi permin (A3.1)
~ !
f o f
FIG. A3.1 Penetration Resistance Versus Elapsed Time
C780 − 23
where:
P and P are as indicated:
f o
A
Mortar for Brick Sized Units Mortar for Heavier Units
P = 1.74 P = 2.44
f f
P = 0.94 P = 1.24
o o
—————
A
The size, weight and bedding area of the unit should be considered in selecting the appropriate values of P and P .
f o
T 5interpolated time when P obtained. (A3.2)
f f
(see Note A3.3)
NOTE A3.3—For graphic illustration, see Fig. A3.1.
A3.8.2 Report T as board life, in minutes. P is approximately equal to the consistency when mortars are judged too stiff to be
f f
used properly.
A3.8.3 Report all penetration resistance data in psi and associated times in minutes.
A3.9 Precision and Bias
A3.9.1 The precision of the procedure in Test Method C780, Annex A3, for measuring consistency and board life is being
determined.
A3.9.2 The procedure in Test Method C780, Annex A3, for measuring the consistency and board life of masonry mortars has no
bias because the value of consistency and board life can be defined only in terms of a test method.
A4. TEST METH
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