ASTM D6608-20

Standard Practice for the Identification of Trinidad Lake Asphalt in Asphalt Mixes

SIGNIFICANCE AND USE
4.1 Asphalt contains sulfur compounds, most of which are removed during refining; the resulting asphalt also contains sulfur compounds which are released at the temperatures above 230 °C. Trinidad Lake Modified Asphalt contains sulfur compounds which are released at lower temperatures between 170 °C and 230 °C. The release of sulfur from Trinidad Lake Modified Asphalt tarnishes the copper strip and appears to be related directly to the total TLA content. The copper strip test is designed to assess the qualitative presence of TLA in asphalt.
Note 1: The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and the capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of Specification D3666 are generally considered capable of competent and objective testing, sampling, inspection, etc. Users of this standard are cautioned that compliance with Specification D3666 alone does not completely ensure reliable results. Reliable results depend on many factors; following the suggestions of Specification D3666 or some similar acceptable guideline provides a means of evaluating and controlling some of those factors.
SCOPE
1.1 This practice shall be used for the qualitative determination of Trinidad Lake Asphalt in Trinidad Lake Modified Asphalt Cements obtained from production blends or recovered binder from asphalt paving mixtures.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This practice is limited to asphalt binders which are produced in accordance with Specification D5710/D5710M.  
1.4 Warning—Mercury has been designated by the United States Environmental Protection Agency and many state agencies as a hazardous material that can cause central nervous system, kidney, and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury-containing products. See the applicable Material Safety Data Sheet (MSDS) for details and EPA’s website—http://www.epa.gov/mercury/index.htm—for additional information. Users should be aware that selling mercury and/or mercury-containing products into your state may be prohibited by state law.  
1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 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-Oct-2020
• ICS: 93.080.20 - Road construction materials
• Technical Committee: D04 - Road and Paving Materials
• Drafting Committee: D04.47 - Miscellaneous Asphalt Tests

Relations

• Refers: ASTM D140/D140M-16(2023) - Standard Practice for Sampling Asphalt Materials
• Effective Date: 01-Dec-2023
• Refers: ASTM D2172/D2172M-17 - Standard Test Methods for Quantitative Extraction of Asphalt Binder from Asphalt Mixtures
• Effective Date: 01-Apr-2017
• Refers: ASTM D2172/D2172M-17e1 - Standard Test Methods for Quantitative Extraction of Asphalt Binder from Asphalt Mixtures
• Effective Date: 01-Apr-2017
• Refers: ASTM D3666-16 - Standard Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
• Effective Date: 01-Oct-2016
• Refers: ASTM D140/D140M-16 - Standard Practice for Sampling Asphalt Materials
• Effective Date: 01-Jun-2016
• Refers: ASTM D140/D140M-15 - Standard Practice for Sampling Bituminous Materials
• Effective Date: 01-Jun-2015
• Refers: ASTM D140/D140M-14 - Standard Practice for Sampling Bituminous Materials
• Effective Date: 01-Jun-2014
• Refers: ASTM D3666-13 - Standard Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
• Effective Date: 01-Dec-2013
• Refers: ASTM D5710/D5710M-13 - Standard Specification for Trinidad Lake Modified Asphalt
• Effective Date: 01-Jun-2013
• Refers: ASTM D3666-11 - Standard Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
• Effective Date: 01-Dec-2011
• Refers: ASTM D2172/D2172M-11 - Standard Test Methods for Quantitative Extraction of Bitumen From Bituminous Paving Mixtures
• Effective Date: 01-Feb-2011
• Refers: ASTM D3666-09a - Standard Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
• Effective Date: 01-Dec-2009
• Refers: ASTM D1856-09 - Standard Test Method for Recovery of Asphalt From Solution by Abson Method
• Effective Date: 01-Jul-2009
• Refers: ASTM D140/D140M-09 - Standard Practice for Sampling Bituminous Materials
• Effective Date: 01-Jun-2009
• Refers: ASTM D3666-07a - Standard Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
• Effective Date: 01-Aug-2007

Overview

ASTM D6608-20 - Standard Practice for the Identification of Trinidad Lake Asphalt in Asphalt Mixes - provides a qualitative method for evaluating the presence and approximate content of Trinidad Lake Asphalt (TLA) in asphalt cements and paving mixtures. Published by ASTM International, this standard is essential for testing the TLA content in asphalt binders, especially those produced according to Specification D5710/D5710M.

The practice uses a copper strip tarnish test to indicate the sulfur compounds unique to TLA, which are released at specific temperatures, distinguishing it from refined asphalt. This test is commonly used for mix designers, testing laboratories, and agencies seeking to verify TLA content in road construction materials.

Key Topics

• Trinidad Lake Asphalt (TLA) Identification: The standard outlines a practice for determining if TLA is present in asphalt mixes by analyzing the characteristic sulfur compounds that react with copper strips under controlled thermal conditions.
• Copper Strip Tarnish Test: A polished copper strip is immersed in a sample of asphalt and heated. The degree and type of tarnish observed on the strip after exposure at set temperatures indicate the qualitative presence and approximate amount of TLA.
• Temperature Sensitivity: Notably, TLA releases sulfur compounds at lower temperatures (170°C - 230°C) than refined asphalt (>230°C). Tarnishing at different temperatures aligns with differing TLA concentrations.
• Sample and Equipment Requirements: The accuracy of results is governed by correct sample preparation, proper maintenance, and calibration of equipment, as well as adherence to related standards such as D3666 for agency competence.
• Safety Precautions: The method involves hazardous substances, including mercury in certain equipment, necessitating strict adherence to safety guidelines and relevant environmental regulations.

Applications

• Asphalt Pavement Quality Control: Ensuring correct TLA content in asphalt mixtures is crucial for projects demanding high-performance road surfaces with improved durability and resistance to deformation.
• Material Verification: Agencies, laboratories, and construction contractors use this standard to verify supplier claims regarding TLA content in asphalts, supporting contractual compliance and material traceability.
• Research and Product Development: The method facilitates comparative studies of paving materials, especially when assessing the performance impacts of different binder compositions or sources.
• Asset Management: Evaluating existing pavement materials for TLA content informs asset condition assessments and maintenance planning.

Related Standards

• ASTM D140/D140M - Sampling Asphalt Materials
• ASTM D1856 - Recovery of Asphalt from Solution
• ASTM D2172/D2172M - Quantitative Extraction of Asphalt Binder
• ASTM D3666 - Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
• ASTM D5710/D5710M - Specification for Trinidad Lake Modified Asphalt
• ASTM E1 - Specification for ASTM Liquid-in-Glass Thermometers

Practical Value

Implementing ASTM D6608-20 ensures reliable identification of Trinidad Lake Asphalt in construction and maintenance of roads, supporting material quality verification and regulatory compliance. The standard is integral for anyone involved in asphalt mix design, quality assurance, and ensuring the functional longevity of road surfaces where TLA-modified binders are specified.

For laboratories and field technicians, following ASTM D6608-20 enhances the accuracy of TLA detection, supports the sustainability of testing practices, and upholds international standardization in asphalt materials testing. Proper use of this practice provides confidence in the asphalt mix’s composition, driving performance, and service life.

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:D6608 −20
Standard Practice for the
Identification of Trinidad Lake Asphalt in Asphalt Mixes
This standard is issued under the fixed designation D6608; 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 mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This practice shall be used for the qualitative determi-
nation of Trinidad Lake Asphalt in Trinidad Lake Modified
2. Referenced Documents
Asphalt Cements obtained from production blends or recov-
2.1 ASTM Standards:
ered binder from asphalt paving mixtures.
D140/D140M Practice for Sampling Asphalt Materials
1.2 The values stated in SI units are to be regarded as
D1856 Test Method for Recovery of Asphalt From Solution
standard. No other units of measurement are included in this
by Abson Method
standard.
D2172/D2172M TestMethodsforQuantitativeExtractionof
1.3 This practice is limited to asphalt binders which are Asphalt Binder from Asphalt Mixtures
produced in accordance with Specification D5710/D5710M. D3666 Specification for Minimum Requirements for Agen-
cies Testing and Inspecting Road and Paving Materials
1.4 Warning—Mercury has been designated by the United
D5710/D5710M Specification for Trinidad Lake Modified
States Environmental ProtectionAgency and many state agen-
Asphalt
cies as a hazardous material that can cause central nervous
system, kidney, and liver damage. Mercury, or its vapor, may
3. Summary of Test Method
be hazardous to health and corrosive to materials. Caution
3.1 Apolished copper strip is immersed in a given quantity
should be taken when handling mercury and mercury-
of sample and heated at a temperature and for a given time
containing products. See the applicable Material Safety Data
characteristic of the material being tested. At the end of this
Sheet (MSDS) for details and EPA’s website—http://
periodthecopperstripisremoved,washed,andcomparedwith
www.epa.gov/mercury/index.htm—for additional information.
the classifications of the TLA Copper Tarnishing Ranges for
Users should be aware that selling mercury and/or mercury-
copper strips.
containing products into your state may be prohibited by state
law.
4. Significance and Use
1.5 The text of this standard references notes and footnotes
4.1 Asphalt contains sulfur compounds, most of which are
which provide explanatory material. These notes and footnotes
removed during refining; the resulting asphalt also contains
(excluding those in tables and figures) shall not be considered
sulfurcompoundswhicharereleasedatthetemperaturesabove
as requirements of the standard.
230 °C. Trinidad Lake Modified Asphalt contains sulfur com-
1.6 This standard does not purport to address all of the
pounds which are released at lower temperatures between
safety concerns, if any, associated with its use. It is the
170 °C and 230 °C. The release of sulfur from Trinidad Lake
responsibility of the user of this standard to establish appro-
Modified Asphalt tarnishes the copper strip and appears to be
priate safety, health, and environmental practices and deter-
related directly to the total TLA content. The copper strip test
mine the applicability of regulatory limitations prior to use.
isdesignedtoassessthequalitativepresenceofTLAinasphalt.
1.7 This international standard was developed in accor-
NOTE 1—The quality of the results produced by this standard are
dance with internationally recognized principles on standard-
dependent on the competence of the personnel performing the procedure
ization established in the Decision on Principles for the
and the capability, calibration, and maintenance of the equipment used.
Development of International Standards, Guides and Recom-
Agencies that meet the criteria of Specification D3666 are generally
considered capable of competent and objective testing, sampling,
inspection, etc. Users of this standard are cautioned that compliance with
Specification D3666 alone does not completely ensure reliable results.
This practice is under the jurisdiction of ASTM Committee D04 on Road and
Paving Materials and is the direct responsibility of Subcommittee D04.47 on
Miscellaneous Asphalt Tests. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2020. Published November 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2000. Last previous edition approved in 2012 as D6608 – 12. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D6608-20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6608−20
Reliable results depend on many factors; following the suggestions of
glass plate with a pad of cotton (cotton wool) moistened with
Specification D3666 or some similar acceptable guideline provides a
a drop of wash solvent. Wipe vigorously with fresh pads of
means of evaluating and controlling some of those factors.
cotton (cotton wool) and subsequently handle only with
stainless steel forceps. Do not touch with fingers. Clamp in a
5. Apparatus
vise and polish the main surfaces with silicone carbide grains
5.1 Test Tubes, 25 by 150 mm.
on absorbent cotton. Do not polish in a circular motion. Rub in
the direction of the long axis of the strip, carrying the stroke
5.2 Provide a bath, which can maintain a constant tempera-
beyondtheendofthestripbeforereversingdirection.Cleanall
ture of 210 6 1 °C and 225 6 1 °C. The bath should have
metaldustfromthestripbyrubbingvigorouslywithcleanpads
suitablesupportstoholdthetesttubesinaverticalpositionand
of absorbent cotton until a fresh pad remains unsoiled. When
immersed to a depth of about 100 mm. Oil or aluminum block
the strip is clean, immediately immerse it in the prepared
baths are suitable.
sample.
5.3 Thermometric Device, partial immersion thermometer
6.2.3.1 Itisimportanttopolishthewholesurfaceofthestrip
forindicatingtherequiredtesttemperature,withgraduationsof
uniformlytoobtainauniformlystainedstrip.Iftheedgesshow
1 °C or less.TheASTM 2C thermometer is suitable.Any other
wear (surface elliptical) they will likely show more corrosion
thermometric device of equal accuracy may be used.
than the center. The use of a vise will facilitate uniform
5.4 Polishing Vise, to hold the copper strip firmly without
polishing.
marring the edge while polishing. Any suitable holder may be
6.2.3.2 It is important to follow the order of preparation
used, provided that the surface is held tightly and the surface
with the correctly sized silicone carbide material as described
being polished is supported above the surface of the holder.
in 6.2.2 and 6.2.3. The final preparation is with 105-µm
silicone carbide grains. This is a larger grain size than the
5.5 Viewing Test Tubes, flat glass test tubes, are c
...

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: D6608 − 12 D6608 − 20
Standard Practice for the
Identification of Trinidad Lake Asphalt in Asphalt Mixes
This standard is issued under the fixed designation D6608; 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 practice shall be used for the qualitative determination of Trinidad Lake Asphalt in Trinidad Lake Modified Asphalt
Cements obtained from production blends or recovered binder from asphalt paving mixtures.
1.2 The values stated isin SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 It This practice is limited to the binder content of Trinidad Lake Modified Asphalt (Specificationasphalt binders which are
produced in accordance with Specification D5710D5710/D5710M) used in the construction of asphalt pavements.
1.4 Warning—Mercury has been designated by the United States Environmental Protection Agency and many state agencies as
a hazardous material that can cause central nervous system, kidney, and liver damage. Mercury, or its vapor, may be hazardous
to health and corrosive to materials. Caution should be taken when handling mercury and mercury containing mercury-containing
products. See the applicable Material Safety Data Sheet (MSDS) for details and EPA’s website—http://www.epa.gov/mercury/
index.htm—for additional information. Users should be aware that selling mercury and/or mercury containing mercury-containing
products into your state may be prohibited by state law.
1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of the standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.7 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:
D140D140/D140M Practice for Sampling Asphalt Materials
D1856 Test Method for Recovery of Asphalt From Solution by Abson Method
D2172D2172/D2172M Test Methods for Quantitative Extraction of Asphalt Binder from Asphalt Mixtures
This practice is under the jurisdiction of ASTM Committee D04 on Road and Paving Materials and is the direct responsibility of Subcommittee D04.47 on Miscellaneous
Asphalt Tests.
Current edition approved Dec. 1, 2012Nov. 1, 2020. Published December 2012November 2020. Originally approved in 2000. Last previous edition approved in 20062012
as D6608 – 00D6608 – 12.(2006). DOI: 10.1520/D6608-12.10.1520/D6608-20.
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
D6608 − 20
D3666 Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
D5710D5710/D5710M Specification for Trinidad Lake Modified Asphalt
E1 Specification for ASTM Liquid-in-Glass Thermometers
3. Summary of Test Method
3.1 A polished copper strip is immersed in a given quantity of sample and heated at a temperature and for a given time
characteristic of the material being tested. At the end of this period the copper strip is removed, washed, and compared with the
classifications of the TLA Copper Tarnishing Ranges for copper strips.
4. Significance and Use
4.1 BitumenAsphalt contains sulfur compounds, most of which are removed during refining,refining; the resulting asphalt cement
also contains sulfur compounds which are released at the temperatures above 230°C.230 °C. Trinidad Lake Modified Asphalt
contains sulfur compounds,compounds which are released at lower temperatures between 170°C170 °C and 230°C.230 °C. The
release of sulfur from Trinidad Lake Modified Asphalt tarnishes the copper strip and appears to be related directly to the total TLA
content. The copper strip test is designed to assess the qualitative presence of TLA in asphalt cements.asphalt.
NOTE 1—The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and the
capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of Specification D3666 are generally considered capable
of competent and objective testing, sampling, inspection, etc. Users of this standard are cautioned that compliance with Specification D3666 alone does
not completely ensure reliable results. Reliable results depend on many factors; following the suggestions of Specification D3666 or some similar
acceptable guideline provides a means of evaluating and controlling some of those factors.
5. Apparatus
5.1 Test Tubes, 25 by 150 mm.
5.2 Provide a bath, which can maintain a constant temperature of 210 6 1°C (410 6 2°F) 1 °C and 225 6 1°C (437 6 2°F). 1 °C.
The bath should have suitable supports to hold the test tubes in a vertical position and immersed to a depth of about 100-mm
(4-in.).100 mm. Oil or aluminum block baths are suitable.
5.3 Thermometric Device, partial immersion thermometer for indicating the required test temperature, with graduations 1°C of
1 °C or less. The ASTM 2C thermometer is suitable. Any other thermometric device of equal accuracy may be used.
5.4 Polishing Vise, to hold the copper strip firmly without marring the edge while polishing. Any suitable holder may be used,
provided that the surface is held tightly and the surface being polished is supported above the surface of the holder.
5.5 Viewing Test Tubes, flat glass test tubes, are convenient for protecting corroded strip and may be used for close inspection and
storage.
6. Materials
6.1 Polishing Materials:
6.1.1 Silicone carbide grip paper of varying degrees of fineness including 65 μm (240 grit) paper or cloth.
6.1.2 Silicone carbide grains 105 μm (150-mesh).
6.1.3 Absorbent cotton (cotton wool), pharmaceutical grade.
6.2 Copper Strips:
6.2.1 Specifications—Use strips 12.5 mm wide, 1.5 to 3.0 mm 3.0 mm thick, cut 75 mm long from smooth-surface, hard temper,
cold-finished copper of 99.9+ % purity; electrical bus bar stock is generally suitable (see Annex A1). The strips may be used
repeatedly but should be discarded when the surfaces become deformed on handling.
6.2.2 Surface Preparation—Remove all surface blemishes from all six sides of the strip with silicone carbide paper of such varying
D6608 − 20
degrees of fineness as are needed to accomplish the desired results efficiently. Finish with 65-μm (240 grit) silicone carbide paper
or cloth, removing all marks that may have been made by other grades of paper used previously. Immerse the strip in wash solvent
from w
...