ASTM C181-11(2018)

Standard Test Method for Workability Index of Fireclay and High-Alumina Refractory Plastics

SIGNIFICANCE AND USE
3.1 Workability index serves as a measure of the facility with which refractory plastic materials can be rammed, gunned, or vibrated into place.  
3.2 Workability index is commonly used to control consistency of plastics during manufacture. It has also been found useful for specification acceptance by the consumer.  
3.3 The workability index determination can provide information for developing a plastic body. When a sample splits under impact at various water contents, it is an indication that the material is “short” or lacking in plasticity.  
3.4 Determinations on samples that split during impact will be difficult to reproduce. If the sample splits, the measurement is not a true indication of deformation. This should be noted in the report.
SCOPE
1.1 This test method covers the determination of the workability index of fireclay and high-alumina refractory plastics by measuring the plastic deformation of a molded test specimen when subjected to impacts.  
1.2 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.  
1.3 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: 30-Sep-2018
• ICS: 81.080 - Refractories
• Technical Committee: C08 - Refractories
• Drafting Committee: C08.09 - Monolithics

Relations

• Replaces: ASTM C181-11 - Standard Test Method for Workability Index of Fireclay and High-Alumina Refractory Plastics
• Effective Date: 01-Oct-2018
• Refers: ASTM D2906-97(2002) - Standard Practice for Statements on Precision and Bias for Textiles (Withdrawn 2008)
• Effective Date: 10-Nov-1997
• Refers: ASTM D2906-97 - Standard Practice for Statements on Precision and Bias for Textiles
• Effective Date: 10-Nov-1997
• Referred By: ASTM C179-14(2019) - Standard Test Method for Drying and Firing Linear Change of Refractory Plastic and Ramming Mix Specimens
• Effective Date: 01-Oct-2018
• Referred By: ASTM C1054-18 - Standard Practice for Pressing and Drying Refractory Plastic and Ramming Mix Specimens
• Effective Date: 01-Oct-2018
• Referred By: ASTM C673-97(2022) - Standard Classification of Fireclay and High-Alumina Plastic Refractories and Ramming Mixes
• Effective Date: 01-Oct-2018
• Referred By: ASTM C71-12(2018) - Standard Terminology Relating to Refractories
• Effective Date: 01-Oct-2018

Overview

ASTM C181-11(2018): Standard Test Method for Workability Index of Fireclay and High-Alumina Refractory Plastics establishes the procedure for determining the workability index of refractory plastics, specifically fireclay and high-alumina materials. This internationally recognized ASTM standard is vital for manufacturers and consumers who need to evaluate the ease of installation and plasticity of refractory plastics that are rammed, gunned, or vibrated into place. By measuring plastic deformation under impact, ASTM C181-11(2018) offers a reliable method to assess product consistency and facilitates quality control across production and procurement cycles.

Key Topics

• Workability Index Definition: The workability index provides a quantitative measure of how easily refractory plastic materials can be installed by ramming, gunning, or vibration.
• Consistency Control: Manufacturers employ the workability index during production to maintain product quality and ensure uniformity across refractory batches.
• Material Development and Specification Acceptance: The test informs both product development and the acceptance criteria specified by end-users.
• Sample Splitting and Plasticity: If a test sample splits under impact, it reveals insufficient plasticity and the result may not be reproducible; such observations should be documented in reports.
• Test Conditions: Key test conditions include maintaining sample temperature between 65 and 75°F (18 and 24°C), molding five test specimens, and ensuring the use of precisely calibrated test equipment.
• Apparatus Requirements: The method utilizes a sand rammer equipped with standardized dimensions and impact energy mechanisms, ensuring repeatable and accurate deformation measurements.
• Reporting: Results are calculated as percentage deformation and averaged to provide the workability index, accompanied by detailed observations and any anomalies encountered during testing.

Applications

The workability index test is crucial in several industrial and commercial contexts, including:

• Quality Assurance in Manufacturing: Refractory producers use the method to monitor and maintain batch consistency, minimizing costly installation failures and ensuring customer satisfaction.
• Specification and Procurement: Consumers and procurement specialists use the workability index as an objective acceptance criterion when purchasing high-alumina and fireclay refractory plastics.
• Research & Development: Material scientists rely on this test during development and formulation optimization to achieve desired workability and performance characteristics.
• Installation Verification: Refractory contractors and end-users apply this method to confirm that delivered materials install smoothly, reducing installation time and material waste.
• Compliance and Certification: The test supports compliance with internationally harmonized standards, facilitating trade and acceptance in regulated industries like steel, cement, and petrochemicals.

Related Standards

Organizations and professionals involved in refractories and high-temperature applications should also be aware of these related ASTM standards:

• ASTM D2906 - Practice for Statements on Precision and Bias for Textiles (Referenced for statistical methodology on data reporting in ASTM C181-11(2018))
• Other Refractory Property Standards - ASTM provides multiple standards for physical properties, installation characteristics, and performance of refractory materials.
• International Guidelines - ASTM C181-11(2018) adheres to the WTO TBT Committee's principles, aligning with ISO and other global standardization bodies.

Practical Value

Using ASTM C181-11(2018) ensures reproducible, objective data for refractory plastic workability, helping stakeholders maintain high-quality installations and production outcomes. Application of this standard streamlines communication between manufacturers, installers, and end-users, reducing disputes and costly failures in industrial refractory applications.

Keywords: ASTM C181-11, workability index, refractory plastics, fireclay, high-alumina, plasticity testing, quality control, industrial standards, installation consistency

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: C181 − 11 (Reapproved 2018)
Standard Test Method for
Workability Index of Fireclay and High-Alumina Refractory
Plastics
This standard is issued under the fixed designation C181; 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 3.2 Workability index is commonly used to control consis-
tency of plastics during manufacture. It has also been found
1.1 This test method covers the determination of the work-
useful for specification acceptance by the consumer.
ability index of fireclay and high-alumina refractory plastics by
measuring the plastic deformation of a molded test specimen
3.3 The workability index determination can provide infor-
when subjected to impacts.
mation for developing a plastic body. When a sample splits
under impact at various water contents, it is an indication that
1.2 The values stated in inch-pound units are to be regarded
the material is “short” or lacking in plasticity.
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only
3.4 Determinations on samples that split during impact will
and are not considered standard.
be difficult to reproduce. If the sample splits, the measurement
is not a true indication of deformation. This should be noted in
1.3 This standard does not purport to address all of the
the report.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Apparatus
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
4.1 Rammer—The apparatus shall consist of the device
1.4 This international standard was developed in accor-
known as the sand rammer for refractories (see Fig. 1). It shall
dance with internationally recognized principles on standard-
consist essentially of a steel cylindrical mold (specimen tube)
ization established in the Decision on Principles for the
2.00 in. (50.8 mm) in inside diameter and 4.75 in. (120.6 mm)
Development of International Standards, Guides and Recom-
in length, supported in a vertical position on the same axis as
mendations issued by the World Trade Organization Technical
a shaft to which shall be fastened a plunger that fits inside the
Barriers to Trade (TBT) Committee.
mold. A 14-lb (6.4-kg) cylindrical weight slides on the same
shaft and is arranged to fall a distance of 2 in. (51 mm) before
2. Referenced Documents
engaging a collar fastened to the shaft.As shown in Fig. 1, the
2.1 ASTM Standards:
weight may be raised by a manually rotated cam. Provision
D2906 Practice for Statements on Precision and Bias for
shall be made by the equipment manufacturer to support the
Textiles (Withdrawn 2008)
weight, thereby removing the load from the vertical shaft
(example shown in Fig. 2). The sand rammer will include a
3. Significance and Use
linear scale capable of measuring sample height to 0.02 in.
3.1 Workability index serves as a measure of the facility (0.5 mm) with a typical range of 1.7 to 2.5 in. (Note 1). The
with which refractory plastic materials can be rammed, portion of the scale to be used shall be adjusted so that when
gunned, or vibrated into place. the vertical shaft is measuring a 3.00-in. standard, 3.00 in. is
read on the scale.
NOTE 1—The apparatus as described in this section is capable of
This test method is under the jurisdiction of ASTM Committee C08 on
measuring workabilities up to about 32 %. For products of higher
Refractories and is the direct responsibility of Subcommittee C08.09 on Monolith-
workability, a suitable spacer block may be installed under the specimen.
ics.
Current edition approved Oct. 1, 2018. Published October 2018. Originally
4.1.1 Mounting for Rammer—It is recommended the ram-
approved in 1943. Last previous edition approved in 2011 as C181 – 11. DOI:
merbemountedonsandrammerbasesoldbythemanufacturer
10.1520/C0181-11R18.
or a concrete column to isolate the rammer from vibration
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
variations. The rammer is to be secured onto the base or
Standards volume information, refer to the standard’s Document Summary page on
column using steel bolts.Variable results are obtained from the
the ASTM website.
test unless the described mounting or an acceptable alternative
The last approved version of this historical standard is referenced on
www.astm.org. mounting is used for the rammer. An acceptable mounting
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C181 − 11 (2018)
FIG. 1 Apparatus for Workability Index Test
producing full ramming energy. This is accomplished by using
calibrated impact rings. Inspect the specimen tube (Note 2).
NOTE 2—Variation in the smoothness and dimensions of the specimen
tube may cause variation in workability values. For referee testing, the
specimen tube may require periodic comparison with a master precision
specimen tube sold by manufacturer.
5. Test Specimens
5.1 Temperature of Refractory Plastic—Since the workabil-
ity index may vary with a wide spread of temperature, the
temperature of the material to be tested must be between 65
and 75 °F (18 and 24 °C) to reduce this variable. Record the
temperature of material before forming the cylinder.
NOTE 3—As much as a three-point change in the workability index may
occur within the 10 °F (6 °C) stated range.
5.2 Number of Specimens—Five cylindrical test specimens
shall be molded from the sample of refractory plastic.
5.3 MoldingofSpecimens—Theinteriorofthemoldshallbe
cleaned and coated with a li
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