ASTM C1446-19

Standard Test Method for Measuring Consistency of Self-Flowing Castable Refractories

SIGNIFICANCE AND USE
5.1 This test method is used to measure the consistency (degree of self-flow) that a castable refractory demonstrates at a given level of tempering liquid at specified time intervals after the liquid is added. A self-flow of 25 % has been selected as the minimum at which a mix can be poured into typical molds or forms in normal practice.  
5.2 Castable refractories which are self-flowing at one level of tempering liquid will require vibration for placement at some lower level of tempering liquid. At the tempering liquid levels which require vibration or tamping for placement, the castable refractory should be characterized using test methods which are appropriate for castable refractories designed for vibration placement, such as Test Method C1445.  
5.3 This test method is not appropriate for determining the pumpability of castable refractories.
SCOPE
1.1 This test method covers the determination of the consistency (degree of self-flow) of self-flowing castable refractories.  
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.  
1.3 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.  
1.4 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.

General Information

• Status: Published
• Publication Date: 31-Aug-2019
• ICS: 81.080 - Refractories
• Technical Committee: C08 - Refractories
• Drafting Committee: C08.09 - Monolithics

Relations

• Replaces: ASTM C1446-11 - Standard Test Method for Measuring Consistency of Self-Flowing Castable Refractories
• Effective Date: 01-Sep-2019
• Refers: ASTM C1445-13(2018) - Standard Test Method for Measuring Consistency of Castable Refractory Using a Flow Table
• Effective Date: 01-Oct-2018
• Refers: ASTM C230/C230M-14 - Standard Specification for Flow Table for Use in Tests of Hydraulic Cement
• Effective Date: 01-Oct-2014
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM C1445-13 - Standard Test Method for Measuring Consistency of Castable Refractory Using a Flow Table
• Effective Date: 01-Sep-2013
• Refers: ASTM C230/C230M-13 - Standard Specification for Flow Table for Use in Tests of Hydraulic Cement
• Effective Date: 01-Jun-2013
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM E177-10 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2010
• Refers: ASTM E177-08 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2008
• Refers: ASTM E691-08 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Oct-2008
• Refers: ASTM C230/C230M-08 - Standard Specification for Flow Table for Use in Tests of Hydraulic Cement
• Effective Date: 01-Jul-2008
• Refers: ASTM C862-02(2008) - Standard Practice for Preparing Refractory Concrete Specimens by Casting
• Effective Date: 01-Mar-2008
• Refers: ASTM C1445-07 - Standard Test Method for Measuring Consistency of Castable Refractory Using a Flow Table
• Effective Date: 01-Mar-2007

Overview

ASTM C1446-19: Standard Test Method for Measuring Consistency of Self-Flowing Castable Refractories provides a standard procedure to determine the consistency or degree of self-flow of castable refractories. This test helps manufacturers and end users assess whether a refractory castable has an adequate self-flow level for placement into molds or forms during installation, ensuring reliable and consistent construction of refractory linings and components. The method also allows for determining the working time of self-flowing castables, which is essential for maintaining product quality and workability on-site.

ASTM C1446-19 is developed by ASTM International and aligns with internationally recognized standardization principles. This standard is particularly relevant in industries that use high-temperature materials, such as iron and steel making, cement production, and petrochemical processing.

Key Topics

• Consistency Measurement: The test establishes a process for measuring the self-flow of a castable refractory after mixing with a tempering liquid. Self-flow is judged by the percentage increase in the spread diameter of the material after mold removal.
• Minimum Self-Flow: A self-flow of 25% is considered the threshold at which a castable mix can be poured into typical molds without vibration or tamping.
• Working Time Determination: The method optionally tracks how long the castable maintains at least 25% self-flow, which is critical for installation planning.
• Factors Affecting Consistency: The test method identifies factors that can influence results, such as mixing liquid quantity, temperature, mold filling method, and mold lifting technique.
• Equipment and Conditions: Testing uses a cone mold, a flow surface, measuring calipers, a castable mixer, and a stopwatch/timer. Precise temperature and mixing control are required for accurate results.
• Limitations: The test is not suitable for determining the pumpability of castable refractories and should not be used for mixes that require vibration at their chosen tempering liquid levels.

Applications

ASTM C1446-19 is widely used across sectors where self-flowing castable refractories are essential for high-temperature operations. Its applications include:

• Refractory Lining Installation: Ensuring the correct consistency of castable refractories is critical for forming durable, defect-free linings in furnaces, kilns, and incinerators.
• Material Quality Control: Manufacturers use this test during product development and quality assurance to verify that their formulations meet required self-flow standards.
• Site Acceptance Testing: Field engineers and on-site teams apply this standard to confirm material suitability prior to installation, reducing the risk of improper placement or poor wear performance.
• Specification Compliance: Procurement and engineering teams rely on results from ASTM C1446-19 testing to ensure purchased materials will perform as expected during project delivery.

Related Standards

ASTM C1446-19 references several standards for terminology, equipment, and related test methods:

• ASTM C71 - Terminology Relating to Refractories
• ASTM C230/C230M - Specification for Flow Table for Use in Tests of Hydraulic Cement
• ASTM C860 - Test Method for Determining the Consistency of Refractory Castable Using the Ball-In-Hand Test
• ASTM C862 - Practice for Preparing Refractory Concrete Specimens by Casting
• ASTM C1445 - Test Method for Measuring Consistency of Castable Refractory Using a Flow Table (for vibration-placed castables)
• ASTM E177 - Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• ASTM E691 - Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

By following ASTM C1446-19 and associated standards, organizations in the refractory industry can achieve consistent product performance, reliable installation, and compliance with international best practices. Incorporating this test method into quality assurance protocols supports the longevity and effectiveness of refractory components in demanding environments.

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: C1446 − 19
Standard Test Method for
Measuring Consistency of Self-Flowing Castable
Refractories
This standard is issued under the fixed designation C1446; 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.
1. Scope 3. Terminology
3.1 Definitions of Terms Specific to This Standard:
1.1 This test method covers the determination of the con-
sistency (degree of self-flow) of self-flowing castable refrac- 3.1.1 consistency of self-flowing castable refractories—the
degree of mobility (self-flow) of the refractory castable under
tories.
its own weight as described in this test method at the specified
1.2 The values stated in inch-pound units are to be regarded
times after adding liquid to the mixer.
as the standard. The values given in parentheses are for
information only.
4. Summary of Test Method
1.3 This standard does not purport to address all of the
4.1 The castable refractory is mixed with a tempering liquid
safety concerns, if any, associated with its use. It is the
and the percentage of self-flow is measured. Self-flow is the
responsibility of the user of this standard to establish appro-
percent increase in the diameter of the sample after removing
priate safety, health, and environmental practices and deter-
the Specification C230/C230M cone mold and allowing the
mine the applicability of regulatory limitations prior to use.
specimen to flow (spread) under its own weight for 120 s.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
5. Significance and Use
ization established in the Decision on Principles for the
5.1 This test method is used to measure the consistency
Development of International Standards, Guides and Recom-
(degree of self-flow) that a castable refractory demonstrates at
mendations issued by the World Trade Organization Technical
a given level of tempering liquid at specified time intervals
Barriers to Trade (TBT) Committee.
after the liquid is added.Aself-flow of 25 % has been selected
as the minimum at which a mix can be poured into typical
2. Referenced Documents
molds or forms in normal practice.
2.1 ASTM Standards:
5.2 Castable refractories which are self-flowing at one level
C230/C230M Specification for Flow Table for Use in Tests
of tempering liquid will require vibration for placement at
of Hydraulic Cement
some lower level of tempering liquid. At the tempering liquid
C862 Practice for Preparing Refractory Concrete Specimens
levels which require vibration or tamping for placement, the
by Casting
castable refractory should be characterized using test methods
C1445 Test Method for Measuring Consistency of Castable
which are appropriate for castable refractories designed for
Refractory Using a Flow Table
vibration placement, such as Test Method C1445.
E177 Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
5.3 This test method is not appropriate for determining the
E691 Practice for Conducting an Interlaboratory Study to
pumpability of castable refractories.
Determine the Precision of a Test Method
6. Interferences (Factors Known to Affect Results)
6.1 During method development, a ruggedness evaluation
This test method is under the jurisdiction of ASTM Committee C08 on
was performed using a castable comprised of 5 % cement,
Refractories and is the direct responsibility of Subcommittee C08.09 on Monolith-
17 % reactive alumina, and 78 % tabular alumina. Several
ics.
factors were found to cause statistically significant effects on
Current edition approved Sept. 1, 2019. Published September 2019. Originally
the measured results. See ASTM Research Report No. C08-
approved in 1999. Previous edition approved in 2011 as C1446 – 11. DOI:
10.1520/C1446-19.
1016.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6.1.1 Amount of Mixing Liquid—The amount of mixing
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
liquid affects the measured results for typical self-flowing
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. castable refractories unless added by weight to within
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1446 − 19
60.002 lb (61 g) of the target weight for a 16.52-lb (7500-g) 7.9 Scoop or Spoon sufficient to fill the cone mold.
sampleweight.Thetargetliquidlevelisapercentageofthedry
weight of the batch.
8. Procedure
6.1.2 Mold Filling Level—During ruggedness testing it was
8.1 All times, amounts, and conditions are to be in accor-
found that filling the mold to a level of ⁄32 in. below the top of
dance with this test method unless others are specified by the
the mold reduced the measured flow at 10 min after adding
castable manufacturer/mix provider. Any deviations will be
liquid to the mixer by approximately 5.5 % for a mix with an
included in the test report; see Section 10.
average flow of approximately 115 % at this elapsed time.
6.1.3 Mold Lifting Technique—During ruggedness testing it 8.2 Ensure all materials and testing equipment that come in
contact with the castable are within 2 °F (1 °C) of the ambient
was found that the technique for lifting the mold from the
sample affected the results. The techniques compared were temperature. During the test, the ambient temperature should
not be allowed to change by more than 2 °F. Whenever
lifting the mold straight up and twisting the mold approxi-
mately 45° as it was lifted off the sample. Twisting the mold possible, the ambient temperature during the test should be in
the 68 to 75 °F (20 to 24 °C) range. Record the actual ambient,
while lifting resulted in an approximate 4.5 % increase in the
measured self-flow at 10 min after adding liquid to the mixer. dry castable and mixing liquid temperatures.
6.2 Factors which were found to be rugged during method
8.3 Ensure all equipment is clean and dry. Remove any
development for percentage self-flow at 10 min after adding
oxidationfromtheflowplate;lightlylubricateandwipedrythe
tempering liquid to the mixer were: (1) ambient temperature
flow plate and flow mold.
when varied from 70 °F to 74 °F, (2) tempering liquid when
8.4 Weigh out the mixing liquid to within 60.002 lb (61g)
varied by 0.1 %, (3) holding time from filling the mold to
of that specified (see 6.1.1).
lifting the mold when varied from 20 to 60 s, and (4)
lubricating the flow surface and wiping clean prior to placing
8.5 Dry mix the batch for 60 s.
the specimen on the flow surface as compared to no lubrication
8.6 Start the timer/stopwatch and add all mixing liquid
on a clean metal surface.
while the mixer is running. The rate of liquid addition can
influence the mixing behavior and thus flow. If all liquid is
7. Apparatus
added too fast, the result may be improper as overly wet
7.1 Cone Mold—The mold used to form the specimen is in
material generally will not pick up dry material from the
accordance with Specification C230/C230M.
bottom of the mixer. Unless known to be problematic, add
7.2 Measuring Caliper—Either a caliper in accordance with
90 % of the estimated water uniformly within 30 s. Add
Specification C230/C230M which reads directly in percent
additional water in small amounts. Use care that none of the
flow, or a standard caliper that can be read to within 60.004 in.
liquid or dry mix is lost. Mixing time and speed shall be as
(60.1 mm) accuracy can be used.
recommendedbytherefractorymanufacturer.At1minpastthe
time of final water addition, stop the mixer, check for dry
7.3 Flow Surface—A metal plate shall be used as the flow
material in the bottom of the bowl, stir in any dry material by
surface for the sample. It shall be thick enough to remain flat
hand if needed, and resume mixing. The timer monitoring the
in use; ⁄8-in. thickness is recommended. The surface shall be
mixing time should be temporarily stopped during the time that
level and confirmed with a leveling device. It shall have a
hand mixing and scraping are occurring. The mixing time
smooth mill finish with any minor imperfections ground
should indicate only the time that mechanical mixing is
smooth. The surface shall not have any circumferential
occurring.
markings, either permanent or temporary. Radial lines scribed
lightly at 45° intervals are recommended to aid in measuring
8.7 Place an excess amount of castable into the mold using
the sample after flow. The surface must be kept clean and free
a scoop or spoon. Consolidation of the castable may be
from oxidation. A galvanized or stainless steel or other non-
neces
...

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: C1446 − 11 C1446 − 19
Standard Test Method for
Measuring Consistency of Self-Flowing Castable
Refractories
This standard is issued under the fixed designation C1446; 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.
1. Scope
1.1 This test method covers the determination of the consistency (degree of self-flow) and working time of self-flowing castable
refractories. This test may optionally be used to determine working time of self-flowing castables.
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information
only.
1.3 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 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:
C71 Terminology Relating to Refractories
C230/C230M Specification for Flow Table for Use in Tests of Hydraulic Cement
C860 Test Method for Determining the Consistency of Refractory Castable Using the Ball-In-Hand Test
C862 Practice for Preparing Refractory Concrete Specimens by Casting
C1445 Test Method for Measuring Consistency of Castable Refractory Using a Flow Table
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 consistency of self-flowing castable refractories—the degree of mobility (self-flow) of the refractory castable under its own
weight as described in this test method at the specified times after adding liquid to the mixer.
3.1.2 working time of self-flowing castable refractories—the elapsed time from the first addition of liquid during mixing until
the mix will only achieve 25 % self-flow using the procedure described in this test method.
4. Summary of Test Method
4.1 The castable refractory is mixed with a tempering liquid and the percentage of self-flow is measured. Self-flow is the percent
increase in the diameter of the sample after removing the Specification C230/C230M cone mold and allowing the specimen to flow
(spread) under itits own weight for 120 s. The consistency is measured 10 min after water addition. Working time may optionally
be determined by repeating the self flow test at regular time intervals.
This test method is under the jurisdiction of ASTM Committee C08 on Refractories and is the direct responsibility of Subcommittee C08.09 on Monolithics.
Current edition approved July 1, 2011Sept. 1, 2019. Published August 2011September 2019. Originally approved in 1999. Previous edition approved in 20072011 as
C1446 – 07.C1446 – 11. DOI: 10.1520/C1446-11.10.1520/C1446-19.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1446 − 19
5. Significance and Use
5.1 This test method is used to measure the consistency (degree of self-flow) that a castable refractory demonstrates at a given
level of tempering liquid at specified time intervals after the liquid is added. A self-flow of 25 % has been selected as the minimum
at which a mix can be poured into typical molds or forms in normal practice.
5.2 Castable refractories which are self-flowing at one level of tempering liquid will require vibration for placement at some
lower level of tempering liquid. At the tempering liquid levels which require vibration or tamping for placement, the castable
refractory should be characterized using test methods which are appropriate for castable refractories designed for vibration
placement, such as Test Method C1445.
5.3 This test method is not appropriate for determining the pumpability of castable refractories.
6. Interferences (Factors Known to Affect Results)
6.1 During method development, a ruggedness evaluation was performed using a castable comprised of 5 % cement, 17 %
reactive alumina, and 78 % tabular alumina. Several factors were found to cause statistically significant effects on the measured
results. See ASTM Research Report No. C08–1016.C08-1016.
6.1.1 Amount of Mixing Liquid—The amount of mixing liquid affects the measured results for typical self-flowing castable
refractories unless added by weight to within 6 0.002 lb (6 1 60.002 lb (61 g) of the target weight for a 16.52–lb16.52-lb
(7500-g) sample weight. The target liquid level is a percentage of the dry weight of the batch.
6.1.2 Temperature—During ruggedness testing the effect of temperature was evaluated. The test mix, tempering liquid, and
room temperature were controlled to the same targets. When the temperature was raised by 3.5°F (70.3 to 73.8°F) working time
was found to be reduced by an average of 10 min. While the degree of this effect may be castable-formulation-dependent, it is
accepted that temperature will affect the working time for all typical self-flowing castables.
6.1.2 Mold Filling Level—During ruggedness testing it was found that filling the mold to a level of ⁄32 in. below the top of the
mold reduced the measured flow at 10 min after adding liquid to the mixer by approximately 5.5 % for a mix with an average flow
of approximately 115 % at this elapsed time.
6.1.3 Mold Lifting Technique—During ruggedness testing it was found that the technique for lifting the mold from the sample
affected the results. The techniques compared were lifting the mold straight up and twisting the mold approximately 45° as it was
lifted off the sample. Twisting the mold while lifting resulted in an appropriateapproximate 4.5 % increase in the measured
self-flow at 10 min after adding liquid to the mixer.
6.2 Factors which were found to be rugged during method development for percentage self-flow at 10 min after adding
tempering liquid to the mixer werewere: (1) ambient temperature when varied from 70°F70 °F to 74°F,74 °F, (2) tempering liquid
when varied by 0.1 %, (3) holding time from filling the mold to lifting the mold when varied from 20 to 60 s, and (4) lubricating
the flow surface and wiping clean prior to placing the specimen on the flow surface as compared to no lubrication on a clean metal
surface.
6.3 Factors which were found to be rugged during method development for working time were (1) holding time from filling the
mold to lifting the mold when varied from 20 to 60 s, (2) lubricating the flow surface and wiping clean prior to placing the
specimen on the flow surface as compared to no lubrication on a clean metal surface, (3) returning the castable to the storage
container after each flow measurement when compared to discarding the castable used for each flow measurement, and (4) storing
the castable in a covered mixing bowl when compared to storing in a sealed container.
7. Apparatus
7.1 Cone Mold—The mold used to form the specimen is in accordance with Specification C230/C230M.
7.2 Measuring Caliper—Either a caliper in accordance with Specification C230/C230M which reads directly in percent flow,
or a standard caliper that can be read to within 6 0.004 in. (6 0.1-mm)60.004 in. (60.1 mm) accuracy can be used used.
7.3 Flow Surface—A metal plate shall be used as the flow surface for the sample. It shall be thick enough to remain flat in
use,use; ⁄8-in. thickness is recommended. The surface shall be level and confirmed with a leveling device. It shall have a smooth
mill finish with any minor imperfections ground smooth. The surface shall not have any circumferential markings, either
permanent or temporary. Radial lines scribed lightly at 45° intervals are recommended to aid in measuring the sample after flow.
The surface must be kept clean and free from oxidation. A galvanized or stainless steel or other nonoxidizing metal is
recommended. If the flow surface is an oxidizing metal, a lightweight oil can be used to prevent oxidation. The surface must be
wiped clean prior to use with an absorbent cloth or clean sponge.
7.4 Mixed Castable Storage Container—The mixed castable may either be stored in the mixer bowl between flow intervals or
transferred to a container for storage. Independent of the storage container used, it must be sealed airtight to prevent evaporation
and must be constructed of a nonporous material. The container size should minimize the air space volume above the stored mixed
castable. No more than double the volume of the stored castable is recommended.
C1446 − 19
7.4 Castable Mixer—The castable mixing equipment shall be in accordance with Practice C862. Care must be exercised to
ensure the appropriate size mixing bowl is chosen. A motor-driven mixer is highly recommended, as many self-flowing castable
refractories require high-energy mixing to achieve their self-flowing consistency at the specified liquid levels.
7.5 Stopwatch/Timer, capable of being read to 1 s.
7.6 Balance, accurate to 0.002 lb (1 g).
7.7 Light Mold Release Oil or Vegetable Oil Cooking Spray.
7.8 Absorbent Cloth or Clean Sponge.
7.9 Scoop or Spoon sufficient to fill the cone mold.
8. Procedure
8.1 All times, amounts, and conditions are to be in accordance with this practice test method unless others are specified by the
castable manufacturer/mix provider. Any deviations will be included in the test report,report; see Section 10.
8.2 Ensure all materials and testing equipment that come in contact with the castable are within 2°F (1°C)2 °F (1 °C) of the
ambient temperature. During the test, the ambient temperature should not be allowed to change by more than 2°F. (see 2 °F. 6.1.2).
Whenever possible, the ambient temperature during the test should be in the 68 to 75°F75 °F (20 to 24°C)24 °C) range. Record
the actual ambient, dry castable,castable and mixing liquid temperatures.
8.3 Ensure all equipment is clean and dry. Remove any oxidation from the flow plate; lightly lubricate and wipe dry the flow
plate and flow mold. Lubricate with a light lubricating oil or a vegetable oil cooking spray. No further lubrication of the flow plate
shall be done until the testing is completed for the day.
8.4 Weigh out the mixing liquid to within 60.002 lb (6 1 (61 g) of that specified (see 6.1.1).
8.5 Dry mix the batch for 3060 s.
8.6 Start the timer/stopwatch and add all mixing liquid within 10 s while the mixer is running. The rate of liquid addition can
influence the mixing behavior and thus flow. If all liquid is added too fast, the result may be improper as overly wet material
generally will not pick up dry material from the bottom of the mixer. Unless known to be problematic, add 90 % of the estimated
water uniformly within 30 s. Add additional water in small amounts. Use care that none of the liquid or dry mix is lost. Mixing
time and speed
...