ASTM D2399-21

Standard Practice for Selection of Cutback Asphalts

SIGNIFICANCE AND USE
4.1 This practice defines various types of bituminous paving construction for which cutback asphalt may be used. In addition, it delineates the types and grades recommended for each specific use.  
4.2 This practice provides the basic concepts on which the use recommendations have been made. It also provides a rationale by which the user may judiciously select a material for a specific job application from among those generally recommended.
SCOPE
1.1 This practice covers the selection of cutback asphalts of the slow, medium, and rapid curing types for various paving and allied uses. Slow-curing cutback asphalts are also called road oils.  
1.2 The values stated in either SI units or English units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.  
1.3 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.  
1.4 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.  
1.5 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-2021
• ICS: 91.100.50 - Binders. Sealing materials
• ICS: 93.080.20 - Road construction materials
• Technical Committee: D04 - Road and Paving Materials
• Drafting Committee: D04.40 - Asphalt Specifications

Relations

• Refers: ASTM D2027/D2027M-19 - Standard Specification for Cutback Asphalt (Medium-Curing Type)
• Effective Date: 01-Dec-2019
• Refers: ASTM D2027/D2027M-13 - Standard Specification for Cutback Asphalt (Medium-Curing Type)
• Effective Date: 01-Aug-2013
• Refers: ASTM D2027/D2027M-10 - Standard Specification for Cutback Asphalt (Medium-Curing Type)
• Effective Date: 01-Jun-2010
• Refers: ASTM D2028/D2028M-10 - Standard Specification for Cutback Asphalt (Rapid-Curing Type)
• Effective Date: 01-Jun-2010
• Refers: ASTM D2026/D2026M-97(2010)e1 - Standard Specification for Cutback Asphalt (Slow-Curing Type)
• Effective Date: 01-Jan-2010

Overview

ASTM D2399-21 - Standard Practice for Selection of Cutback Asphalts provides essential guidelines for the selection of various types and grades of cutback asphalts used in bituminous paving and related construction applications. Published by ASTM International, this standard addresses the key characteristics, applications, and selection criteria for slow-, medium-, and rapid-curing cutback asphalts, supporting construction quality and durability.

Cutback asphalts-bituminous materials dissolved in solvents of varying volatility-are widely used in road construction, surfacing, surface treatments, tack coats, cold-laid mixtures, and patching. The standard outlines considerations for selecting the best type based on project requirements, local practices, environmental factors, and specific use cases within paving and road maintenance.

Key Topics

ASTM D2399-21 covers critical concepts for the use and selection of cutback asphalts, including:

• Types of Cutback Asphalts:

  • Slow-curing (SC) - also referred to as road oils, uses low volatility solvents
  • Medium-curing (MC) - uses moderate volatility solvents
  • Rapid-curing (RC) - uses highly volatile solvents

• Paving Construction Applications:

  • Surface treatments (single or multiple applications)
  • Prime and tack coats
  • Dust binders
  • Patch mixes for repairs
  • Penetration macadam
  • Cold-laid plant mixes
  • Mixed-in-place (road mix)
  • Sand and sand seals
  • Mulch treatments

• Selection Criteria:
  Recommendations are based on factors such as:

  • Aggregate gradation (open-graded vs. dense-graded)
  • Type of pavement structure (base, surface)
  • Climatic conditions during construction
  • Method of application or mixing

• Curing Rates and Handling:

  • Understanding volatility and curing time is crucial to match job site needs
  • Safety and environmental practices are mandatory considerations, especially as some applications involve handling hot materials above flash point temperatures

Applications

ASTM D2399-21 is integral to ensuring best practices in the following scenarios:

• Road and Pavement Construction:
  Selecting the appropriate cutback asphalt enhances the durability, waterproofing, and bonding of pavement layers, directly benefiting the longevity of roads, parking lots, and transportation routes.

• Surface Treatments and Seals:
  Using rapid- or medium-curing asphalts for surface and sand seals protects pavement surfaces from oxidation, water penetration, and rutting, while improving skid resistance.

• Prime and Tack Coats:
  Application of slow- or medium-curing cutbacks to base layers and between pavement lifts ensures strong adhesion and uniformity between new and existing surfaces.

• Patching and Repairs:
  Cold-laid and stockpile patch mixes utilizing cutback asphalts facilitate effective maintenance of deteriorated or potholed pavements, allowing for year-round repairs.

• Specialty Treatments:
  Dust binders and mulch treatments, as specified in the standard, promote dust control on rural roads and temporary stabilization of erodible terrain.

Related Standards

To ensure full compliance and optimize the selection process, reference is also made to the following ASTM standards:

• ASTM D2026 - Specification for Cutback Asphalt (Slow-Curing Type)
• ASTM D2027 - Specification for Cutback Asphalt (Medium-Curing Type)
• ASTM D2028 - Specification for Cutback Asphalt (Rapid-Curing Type)

These related documents provide further technical specifications and classification details for each particular type of cutback asphalt, supporting comprehensive material selection and verification.

---

ASTM D2399-21 is widely recognized for its practical approach to cutback asphalt selection, making it an invaluable resource for civil engineers, contractors, and professionals engaged in asphalt pavement design, maintenance, and construction. Adhering to this standard helps maximize pavement performance, safety, and regulatory compliance.

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: D2399 − 21
Standard Practice for
Selection of Cutback Asphalts
This standard is issued under the fixed designation D2399; 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 D2028/D2028M Specification for Cutback Asphalt (Rapid-
Curing Type)
1.1 This practice covers the selection of cutback asphalts of
the slow, medium, and rapid curing types for various paving
3. Terminology
and allied uses. Slow-curing cutback asphalts are also called
3.1 Definitions:
road oils.
3.1.1 bitumen-aggregate applications—the spraying of liq-
1.2 The values stated in either SI units or English units are
uid bitumen on prepared aggregate or pavement surfaces,
to be regarded separately as standard.The values stated in each
which subsequently are covered with graded aggregate.
system may not be exact equivalents; therefore, each system
3.1.2 bitumen-aggregate mixture—a combination of bitumi-
shall be used independently of the other. Combining values
nous material and aggregate that is physically mixed by
from the two systems may result in nonconformance with the
mechanical and thermal means, spread on the job site, and
standard.
compacted.
1.3 The text of this standard references notes and footnotes
3.1.3 bitumen applications—the uses of sprayed bituminous
which provide explanatory material. These notes and footnotes
coatings not involving the use of aggregates. Uses of liquid
(excluding those in tables and figures) shall not be considered
bitumeninthisgroupareallclassedastreatments.(See surface
as requirements of the standard.
treatments.)
1.4 This standard does not purport to address all of the
3.1.4 cold-laid plant mix—a mixture of liquid bitumen and
safety concerns, if any, associated with its use. It is the
mineral aggregate prepared in a central bituminous mixing
responsibility of the user of this standard to establish appro-
plant and spread and compacted at the job site when the
priate safety, health, and environmental practices and deter-
mixture is at or near ambient temperature.
mine the applicability of regulatory limitations prior to use.
3.1.5 dense-graded aggregate—aggregate that is graded
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard- from the maximum size down to filler with the object of
ization established in the Decision on Principles for the obtaining a bituminous mix with a controlled void content and
Development of International Standards, Guides and Recom- high stability.
mendations issued by the World Trade Organization Technical
3.1.6 dust binder—a light application of bituminous mate-
Barriers to Trade (TBT) Committee.
rial for the express purpose of laying and bonding loose dust.
3.1.7 mixed-in-place (road mix)—a bituminous course pro-
2. Referenced Documents
duced by mixing mineral aggregate and liquid bitumen at the
2.1 ASTM Standards:
job site by means of travel plants, motor graders, drags, or
D2026/D2026M Specification for Cutback Asphalt (Slow-
special road-mixing equipment. Pavement base and surfaces,
Curing Type)
mixed in place, may utilize open-graded aggregates (3.1.10),
D2027/D2027M Specification for Cutback Asphalt
dense-graded aggregates (3.1.5), sand (3.1.14), or sandy soil
(Medium-Curing Type)
(3.1.16).
3.1.8 mulch treatment—a spray application of bituminous
1 material used to temporarily stabilize a recently seeded area.
This practice is under the jurisdiction of ASTM Committee D04 on Road and
Paving Materials and is the direct responsibility of Subcommittee D04.40 on The bitumen can also be applied to straw or hay mulch as a
Asphalt Specifications.
tie-down.
Current edition approved Nov. 1, 2021. Published November 2021. Originally
3.1.9 multiple surface treatment—two or more surface treat-
approved in 1965. Last previous edition approved in 2017 as D2399 – 12 (2017).
DOI: 10.1520/D2399-21.
ments placed one on the other.The maximum aggregate size of
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
each successive treatment is usually one half that of the
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
previous one, and the total thickness is about the same as the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. nominal maximum size aggregate particles of the first course.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2399 − 21
3.1.10 open-graded aggregate—one containing little or no rationale by which the user may judiciously select a material
mineral filler and in which the void spaces in the compacted for a specific job application from among those generally
aggregate are relatively large. recommended.
3.1.11 pavement base and surfaces—the lower or underly-
5. Precautions
ing pavement course atop the subbase or subgrade and the top
5.1 For some of the uses recommended in Table 1, the
or wearing course. Cold-laid mixtures that are bound together
cutback asphalt may be applied at temperatures above its flash
with liquid bitumens use either open or dense aggregate
point. Caution must therefore be exercised at all times in
gradations.
handling these materials to prevent fire or an explosion.
3.1.12 penetration macadam—a pavement construction us-
6. Recommended Uses
ing essentially one-size coarse aggregate, which is penetrated
6.1 The recommendations shown in Table 1 are for use only
in place by a heavy application of high-viscosity bituminous
as a guide in paving and road construction. Several cutback
material. This application is followed by an application of a
materials may be recommended in the table for a general
smaller size coarse aggregate (to reduce the void space) then is
construction procedure. Selection of a particular material will
rolled thoroughly. This procedure is usually followed another
depend on local practice, availability, traffic, and environmen-
time with a still smaller coarse aggregate and roller compac-
tal conditions for the specific project being considered.
tion.
6.2 Cutback asphalts are constituted from a base asphalt of
3.1.13 prime coat—an application of a low-viscosity bitu-
selected hardness or viscosity dissolved in a solvent of high,
minous material to an absorptive surface, designed to
medium, or low volatility to provide distinct differences for
penetrate, bond, and stabilize the existing surface and to
construction purpo
...

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.
´1
Designation: D2399 − 12 (Reapproved 2017) D2399 − 21
Standard Practice for
Selection of Cutback Asphalts
This standard is issued under the fixed designation D2399; 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.
ε NOTE—Section 1 was updated editorially in October 2017.
1. Scope
1.1 This practice covers the selection of cutback asphalts of the slow, medium, and rapid curing types for various paving and allied
uses. Slow-curing cutback asphalts are also called road oils.
1.2 The values stated in either SI units or English units are to be regarded separately as standard. The values stated in each system
may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two
systems may result in nonconformance with the standard.
1.3 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.
1.4 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.
1.5 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:
D2026D2026/D2026M Specification for Cutback Asphalt (Slow-Curing Type)
D2027D2027/D2027M Specification for Cutback Asphalt (Medium-Curing Type)
D2028D2028/D2028M Specification for Cutback Asphalt (Rapid-Curing Type)
3. Terminology
3.1 Definitions:
3.1.1 bitumen-aggregate applications—the spraying of liquid bitumen on prepared aggregate or pavement surfaces, which
subsequently are covered with graded aggregate.
This practice is under the jurisdiction of ASTM Committee D04 on Road and Paving Materials and is the direct responsibility of Subcommittee D04.40 on Asphalt
Specifications.
Current edition approved Oct. 1, 2017Nov. 1, 2021. Published October 2017November 2021. Originally approved in 1965. Last previous edition approved in 20122017
as D2399 – 12.D2399 – 12 (2017). DOI: 10.1520/D2399-12R17E01.10.1520/D2399-21.
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
D2399 − 21
3.1.2 bitumen-aggregate mixture—a combination of bituminous material and aggregate that is physically mixed by mechanical
and thermal means, spread on the job site, and compacted.
3.1.3 bitumen applications—the uses of sprayed bituminous coatings not involving the use of aggregates. Uses of liquid bitumen
in this group are all classed as treatments. (See surface treatments.)
3.1.4 cold-laid plant mix—a mixture of liquid bitumen and mineral aggregate prepared in a central bituminous mixing plant and
spread and compacted at the job site when the mixture is at or near ambient temperature.
3.1.5 dense-graded aggregate—aggregate that is graded from the maximum size down to filler with the object of obtaining a
bituminous mix with a controlled void content and high stability.
3.1.6 dust binder—a light application of bituminous material for the express purpose of laying and bonding loose dust.
3.1.7 mixed-in-place (road mix)—a bituminous course produced by mixing mineral aggregate and liquid bitumen at the job site
by means of travel plants, motor graders, drags, or special road-mixing equipment. Pavement base and surfaces, mixed in place,
may utilize open-graded aggregates (3.1.10), dense-graded aggregates (3.1.5), sand (3.1.15), or sandy soil (3.1.17).
3.1.8 mulch treatment—a spray application of bituminous material used to temporarily stabilize a recently seeded area. The
bitumen can also be applied to straw or hay mulch as a tie-down.
3.1.9 multiple surface treatment—two or more surface treatments placed one on the other. The maximum aggregate size of each
successive treatment is usually one-half that of the previous one, and the total thickness is about the same as the nominal maximum
size aggregate particles of the first course.
3.1.10 open-graded aggregate—one containing little or no mineral filler and in which the void spaces in the compacted aggregate
are relatively large.
3.1.11 patch mix—a mixture of bituminous material and mineral aggregate for patching holes, depressions, and distressed areas
in existing pavements. These mixes are suitable for use in relatively small areas, applied at ambient temperature using hand-laying
and hand-compaction techniques. These mixes may be designed for immediate use or for stockpiling for a period of time prior to
use.
3.1.12 pavement base and surfaces—the lower or underlying pavement course atop the subbase or subgrade and the top or wearing
course. Cold-laid mixtures that are bound together with liquid bitumens use either open or dense aggregate gradations.
3.1.13 penetration macadam—a pavement construction using essentially one-size coarse aggregate, which is penetrated in place
by a heavy application of high-viscosity bituminous material. This application is followed by an application of a smaller size coarse
aggregate (to reduce the void space) then is rolled thoroughly. This procedure is usually followed another time with a still smaller
coarse aggregate and roller compaction.
3.1.14 prime coat—an application of a low-viscosity bituminous material to an absorptive surface, designed to penetrate, bond,
and stabilize the existing surface and to promote adhesion between it and the construction course that follows.
3.1.15 sand—a clean, mineral aggregate material passing a No. 4 (4.75-mm) sieve, but only about 5 % passing the No. 200
(75-μm) sieve.
3.1.16 sand seal—a thin layer of spray-applied bitumen uniformly covered with sand (see 3.1.15), which waterproofs and
improves the texture of a pavement surface.
3.1.17 sandy soil—a material consisting essentially of fine aggregate particles smaller than No. 10 (2.00-mm) sieve and usually
containing up to 20 % passing a No. 200 (75-μm) sieve. This material usually exhibits plasticity characteristics.
3.1.18 single-surface treatment—a single application of bitumen to any kind of road surface followed immediately by a single
layer of aggregate of as uniform a size as practicable. The thickness of the treatment is about the same as the nominal maximum
size aggregate particles. A single-surface treatment is used as a wearing and waterproofing course.
D2399 − 21
3.1.19 surface treatments—applications of bituminous materials to any type of road or pavement surface that produce an increase
in thickness of less than 25mm (1 in.).
3.1.20 tack coat—an application of bituminous material applied to an existing, relatively nonabsorbent surface to provide a
thorough bond between old and new surfacing.
3.1 Definitions:
3.1.1 bitumen-aggregate applications—the spraying of liquid bitumen on prepared aggregate or pavement surfaces, which
subsequently are covered with graded aggregate.
3.1.2 bitumen-aggregate mixture—a combination of bituminous material and aggregate that is physically mixed by mechanical
and thermal means, spread on the job site, and compacted.
3.1.3 bitumen applications—the uses of sprayed bituminous coatings not involving the use of aggregates. Uses of liquid bitumen
in this group are all classed as treatments. (See surface treatments.)
3.1.4 cold-laid plant mix—a mixture of liquid bitumen and mineral aggregate prepared in a central bituminous mixing plant and
spread and compacted at the job site when the mixture is at or near ambient temperature.
3.1.5 dense-graded aggregate—aggregate that is graded from the maximum size down to filler with the object of obtaining a
bituminous mix with a controlled void content and high stability.
3.1.6 dust binder—a light application of bituminous material for the express purpose of laying and bonding loose dust.
3.1.7 mixed-in-place (road mix)—a bituminous course produced by mixing mineral aggregate and liquid bitumen at the job site
by means of travel plants, motor graders, drags, or special road-mixing equipment. Pavement base and surfaces, mixed in place,
may utilize open-graded aggregates (3.1.10), dense-graded aggregates (3.1.5), sand (3.1.14), or sandy soil (3.1.16).
3.1.8 mulch treatment—a spray appl
...