ASTM D1635/D1635M-19

Standard Test Method for Flexural Strength of Soil-Cement Using Simple Beam with Third-Point Loading 

SIGNIFICANCE AND USE
5.1 This test method is used to determine the flexural strength of soil-cement. Flexural strength is significant in pavement design and can be used to determine the thickness of pavement layers.
Note 2: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.
SCOPE
1.1 This test method covers the determination of the flexural strength of soil-cement by the use of a simple beam with third-point loading.  
Note 1: For methods of molding soil-cement specimens, see Practice D1632.  
1.2 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined. The SI units are presented in brackets.  
1.2.1 The gravitational system of inch-pound units is used when dealing with inchpound units. In this system, the pound (lbf) represents a unit of force (weight), while the unit for mass is slugs. The rationalized slug unit is not given, unless dynamic (F = ma) calculations are involved.  
1.3 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.  
1.3.1 The procedures used to specify how data are collected/recorded or calculated in the standard are regarded as industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s objectives; and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analysis methods for engineering design.  
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-2019
• ICS: 93.020 - Earthworks. Excavations. Foundation construction. Underground works
• Technical Committee: D18 - Soil and Rock
• Drafting Committee: D18.15 - Stabilization With Admixtures

Relations

• Replaces: ASTM D1635/D1635M-12 - Standard Test Method for Flexural Strength of Soil-Cement Using Simple Beam with Third-Point Loading
• Effective Date: 01-Nov-2019
• Refers: ASTM D3740-23 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Nov-2023
• Refers: ASTM D3740-19 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Oct-2019
• Refers: ASTM D2216-19 - Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
• Effective Date: 01-Mar-2019
• Refers: ASTM D1632-17 - Standard Practice for Making and Curing Soil-Cement Compression and Flexure Test Specimens in the Laboratory
• Effective Date: 01-Nov-2017
• Refers: ASTM D1632-17e1 - Standard Practice for Making and Curing Soil-Cement Compression and Flexure Test Specimens in the Laboratory
• Effective Date: 01-Nov-2017
• Refers: ASTM D653-14 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Aug-2014
• Refers: ASTM E4-14 - Standard Practices for Force Verification of Testing Machines
• Effective Date: 01-Jun-2014
• Refers: ASTM D3740-12a - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-May-2012
• Refers: ASTM D3740-12 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Mar-2012
• Refers: ASTM D3740-11 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Sep-2011
• Refers: ASTM D653-11 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Sep-2011
• Refers: ASTM D2216-10 - Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
• Effective Date: 01-Jul-2010
• Refers: ASTM E4-10 - Standard Practices for Force Verification of Testing Machines
• Effective Date: 01-Jun-2010
• Refers: ASTM D3740-10 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Mar-2010

Overview

ASTM D1635/D1635M-19 is the internationally recognized standard test method for determining the flexural strength of soil-cement using a simple beam with third-point loading. Published by ASTM International, this standard is vital for evaluating the mechanical performance of soil-cement, particularly in the context of pavement design and soil stabilization projects. Accurate measurement of flexural strength allows engineers to optimize pavement layer thickness and ensures long-term performance in transportation infrastructure applications.

Key Topics

• Flexural Strength Measurement: Outlines procedures for assessing the bending resistance (modulus of rupture) of soil-cement beams using a third-point loading apparatus.
• Test Specimen Preparation: Refers to ASTM D1632 for molding and curing soil-cement test specimens to ensure consistency and reproducibility.
• Apparatus Requirements:
  • Compression testing machine compliant with ASTM E4 for force verification.
  • Flexural testing apparatus designed for third-point loading, ensuring vertical force application without load eccentricity.
  • Accurate measuring tools for verifying specimen dimensions.
• Data Collection and Reporting:
  • Strict adherence to guidelines on significant digits and rounding (per ASTM D6026).
  • Comprehensive documentation including specimen dimensions, span length, maximum load, fracture location, modulus of rupture, defects, age, water content, and curing details.
• Precision and Bias: Offers guidance on interpreting test variability and emphasizes the importance of operator competence and equipment suitability, referencing ASTM D3740 for laboratory quality assurance.

Applications

The ASTM D1635/D1635M-19 standard is widely used in geotechnical engineering, construction, and materials testing laboratories for:

• Pavement Design: Determination of soil-cement flexural strength is crucial in designing pavement systems, directly influencing the thickness and durability of pavement layers.
• Soil Stabilization Projects: Evaluating the performance of soil-cement in resisting bending under load enables project teams to select optimal material blends and curing methods.
• Quality Control: Testing during soil-cement production and installation helps verify material compliance with engineering specifications and regulatory standards.
• Research and Development: Assists in material characterization studies and the development of new soil-cement mixtures for enhanced durability and performance.

Related Standards

ASTM D1635/D1635M-19 references several other ASTM standards to ensure rigorous, standard-compliant soil-cement testing:

• ASTM D1632: Practice for Making and Curing Soil-Cement Compression and Flexure Test Specimens in the Laboratory.
• ASTM D653: Terminology Relating to Soil, Rock, and Contained Fluids.
• ASTM D2216: Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass.
• ASTM D3740: Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction.
• ASTM D6026: Practice for Using Significant Digits in Geotechnical Data.
• ASTM E4: Practices for Force Verification of Testing Machines.

Practical Value

Adhering to ASTM D1635/D1635M-19 ensures reliable, reproducible measurements of soil-cement flexural strength, supporting pavement designers, construction engineers, and quality assurance professionals in delivering safe, compliant, and cost-effective infrastructure projects. Through standardization, this method enhances data comparability across organizations and jurisdictions, advancing best practices in soil-cement testing worldwide.

Keywords: ASTM D1635/D1635M-19, flexural strength, soil-cement, third-point loading, pavement design, soil stabilization, geotechnical testing, standard test method.

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: D1635/D1635M − 19
Standard Test Method for
Flexural Strength of Soil-Cement Using Simple Beam with
Third-Point Loading
This standard is issued under the fixed designation D1635/D1635M; 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* priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 Thistestmethodcoversthedeterminationoftheflexural
1.5 This international standard was developed in accor-
strength of soil-cement by the use of a simple beam with
third-point loading. dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
NOTE 1—For methods of molding soil-cement specimens, see Practice
Development of International Standards, Guides and Recom-
D1632.
mendations issued by the World Trade Organization Technical
1.2 Units—The values stated in either SI units or inch-
Barriers to Trade (TBT) Committee.
pound units are to be regarded separately as standard. The
values stated in each system are not necessarily exact equiva-
2. Referenced Documents
lents; therefore, to ensure conformance with the standard, each
system shall be used independently of the other, and values
2.1 ASTM Standards:
from the two systems shall not be combined. The SI units are
D653 Terminology Relating to Soil, Rock, and Contained
presented in brackets.
Fluids
1.2.1 The gravitational system of inch-pound units is used
D1632 Practice for Making and Curing Soil-Cement Com-
when dealing with inchpound units. In this system, the pound
pression and Flexure Test Specimens in the Laboratory
(lbf) represents a unit of force (weight), while the unit for mass
D2216 Test Methods for Laboratory Determination of Water
is slugs.The rationalized slug unit is not given, unless dynamic
(Moisture) Content of Soil and Rock by Mass
(F = ma) calculations are involved.
D3740 Practice for Minimum Requirements for Agencies
1.3 All observed and calculated values shall conform to the
Engaged in Testing and/or Inspection of Soil and Rock as
guidelines for significant digits and rounding established in
Used in Engineering Design and Construction
Practice D6026.
D6026 Practice for Using Significant Digits in Geotechnical
1.3.1 Theproceduresusedtospecifyhowdataarecollected/
Data
recorded or calculated in the standard are regarded as industry
E4 Practices for Force Verification of Testing Machines
standard. In addition, they are representative of the significant
digits that generally should be retained. The procedures used
3. Terminology
do not consider material variation, purpose for obtaining the
3.1 For definitions of common technical terms used in this
data, special purpose studies, or any considerations for the
standard, refer to Terminology D653.
user’s objectives; and it is common practice to increase or
reduce significant digits of reported data to be commensurate
3.2 Definitions of Terms Specific to This Standard:
with these considerations. It is beyond the scope of this
3.2.1 flexural strength, n—maximum resistance of a speci-
standard to consider significant digits used in analysis methods
men subjected to bending.
for engineering design.
3.2.2 modulus of rupture, n—calculated stress, assuming
1.4 This standard does not purport to address all of the
linear-elastic behavior, in the tensile face of a beam specimen
safety concerns, if any, associated with its use. It is the
at the maximum bending moment during a standard test
responsibility of the user of this standard to establish appro-
method.
This test method is under the jurisdiction ofASTM Committee D18 on Soil and
Rock and is the direct responsibility of Subcommittee D18.15 on Stabilization With
Admixtures. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2019. Published December 2019. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1959. Last previous edition approved in 2012 as D1635 – 12. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D1635_D1635M-19. the ASTM website.
*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
D1635/D1635M − 19
4. Summary of Test Method width of the beam but not greatly in excess of the width of the
beam. The movable portion of this block shall be held closely
4.1 A beam, typically 3 by 3 by 11 ⁄4 in. [76 by 76 by 290
in the spherical seat, but the design shall be such that the
mm], is placed in a third-point loading apparatus and loaded
bearing face may be rotated freely and tilted through small
until failure.
angles in any direction. The compression machine shall be
4.2 The maximum applied load, specimen dimensions, and
verified in accordance with Practice E4 at least annually to
span length are used to calculate the modulus of rupture.
determine if indicated loads are accurate to 61.0 % in the
4.3 Practice D1632 provides methods of molding soil- applicable range of loading
cement test specimens.
6.2 Flexural Testing Apparatus—Afour-point loading appa-
ratus shall employ bearing blocks that will ensure that forces
5. Significance and Use
applied to the beam will be vertical only and applied without
5.1 This test method is used to determine the flexural
eccentricity. A diagrammatic drawing of an apparatus that
strength of soil-cement. Flexural strength is significant in
accomplishes this purpose is shown in Fig. 1. This type of
pavement design and can be used to determine the thickness of
loading apparatus is commonly referred to as third-point
pavement layers.
loading since the bearing blocks are located at third points of
NOTE 2—The quality of the result produced by this standard is the span.
dependent on the competence of the personnel performing it, and the
6.2.1 The apparatus shall be designed to incorporate the
suitability of the equipment and facilities used. Agencies that meet the
following principles:
criteria of Practice D3740 are generally considered capable of competent
and objective testing/sampling/inspection/etc. Users of this standard are 6.2.1.1 The distance between supports and points of load
cautioned that compliance with Practice D3740 does not in itself assure
application shall remain constant for a given apparatus.
reliable results. Reliable results depend on many factors; Practice D3740
6.2.1.2 The direction of the reactions shall be parallel to the
provides a means of evaluating some of those factors.
direction of the applied load at all times during the test.
6. Apparatus
6.2.1.3 The directions of loads and reactions may be main-
tained parallel by judicious use of linkages, rocker bearings,
6.1 Compression Testing Machine—The testing machine
and flexure plates. Eccentricity of loading can be avoided by
may be of any type having sufficient capacity and control to
use of spherical bearings.
provide the rate of displacement or loading prescribed in 8.2.
Thetestingmachineshallbeequippedwithasphericallyseated 6.2.1.4 Thesteelplateandbedoftestingmachineshallbeof
head block having a bearing surface of at least 75 % of the sufficient hardness and size to support the testing apparatus.
FIG. 1 Diagrammatic View of Suitable Apparatus for Flexure Test of Soil-Cement by Third-Point Loading Method
D1635/D1635M − 19
6.3 Drying Oven—Conforming to the requirements of Test away as much material as practicable from the capping, for the
Methods D2216. water content specimen.
6.4 Measuring Device—A measuring device suitable for
9. Measurement of Specimens After Test
measuring the width and depth of test specimens to the nearest
9.1 Record the following measurements.
0.01 in. [0.25 mm].
9.1.1 Confirm the width and depth of the specimen, at the
section of failure, to the nearest 0.01 in. [0.25 mm].
7. Test Specimens
9.1.2 The span length to the nearest 0.1 in. [2.5 mm].
7.1 The standard test spe
...

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: D1635/D1635M − 12 D1635/D1635M − 19
Standard Test Method for
Flexural Strength of Soil-Cement Using Simple Beam with
Third-Point Loading
This standard is issued under the fixed designation D1635/D1635M; 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 flexural strength of soil-cement by the use of a simple beam with third-point
loading.
NOTE 1—For methods of molding soil-cement specimens, see Practice D1632.
1.2 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice
D6026 unless superseded by this standard.
1.2 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated
in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other, and values from the two systems shall not be combined. The SI units are presented in brackets.
1.2.1 The gravitational system of inch-pound units is used when dealing with inchpound units. In this system, the pound (lbf)
represents a unit of force (weight), while the unit for mass is slugs. The rationalized slug unit is not given, unless dynamic (F =
ma) calculations are involved.
1.3 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice
D6026.
1.3.1 The procedures used to specify how data are collected/recorded or calculated in the standard are regarded as industry
standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not
consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s objectives;
and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations.
It is beyond the scope of this standard to consider significant digits used in analysis methods for engineering design.
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 safety, health, and healthenvironmental 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:
D653 Terminology Relating to Soil, Rock, and Contained Fluids
D1632 Practice for Making and Curing Soil-Cement Compression and Flexure Test Specimens in the Laboratory
D2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
D3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in
Engineering Design and Construction
D6026 Practice for Using Significant Digits in Geotechnical Data
E4 Practices for Force Verification of Testing Machines
This test method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.15 on Stabilization With
Admixtures.
Current edition approved May 1, 2012Nov. 1, 2019. Published June 2012December 2019. Originally approved in 1959. Last previous edition approved in 20002012 as
D1635 – 00D1635 – 12.(2006). DOI: 10.1520/D1635_D1635M-12.10.1520/D1635_D1635M-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.
*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
D1635/D1635M − 19
3. Terminology
3.1 For common definitions of common technical terms used in this standard, refer to Terminology D653.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 flexural strength, n—maximum resistance of a specimen subjected to bending.
3.2.2 modulus of rupture, n—calculated stress, assuming linear-elastic behavior, in the tensile face of a beam specimen at the
maximum bending moment during a standard test method.
4. Summary of Test Method
4.1 A beam, typically 3 by 3 by 11 ⁄4 in. [76 by 76 by 290 mm], is placed in a third-point loading apparatus and loaded until
failure.
4.2 The maximum applied load, specimen dimensions, and span length are used to calculate the modulus of rupture.
4.3 Practice D1632 provides methods of molding soil-cement test specimens.
5. Significance and Use
5.1 This test method is used to determine the flexural strength of soil-cement. Flexural strength is significant in pavement design
and is can be used to determine slab thickness.the thickness of pavement layers.
NOTE 2—The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the
equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective
testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable
results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.
6. Apparatus
6.1 Compression Testing Machine—The testing machine may be of any type having sufficient capacity and control to provide
the rate of displacement or loading (prescribedprescribed in 7.28.2). It shall conform to the requirements of Section 15 of Practices
E4. The testing machine shall be equipped with a spherically seated head block having a bearing surface of at least 75 % of the
width of the beam but not greatly in excess of the width of the beam. The movable portion of this block shall be held closely in
the spherical seat, but the design shall be such that the bearing face may be rotated freely and tilted through small angles in any
direction. The compression machine shall be verified in accordance with Practice E4 at least annually to determine if indicated
loads are accurate to 61.0 % in the applicable range of loading
6.2 Flexural Testing Apparatus—The third-point loading method used in making flexure tests of soil-cement A four-point
loading apparatus shall employ bearing blocks that will ensure that forces applied to the beam will be vertical only and applied
without eccentricity. A diagrammatic drawing of an apparatus that accomplishes this purpose is shown in Fig. 1. The apparatus
shall be designed to incorporate the following principles:This type of loading apparatus is commonly referred to as third-point
loading since the bearing blocks are located at third points of the span.
5.2.1 The distance between supports and points of load application shall remain constant for a given apparatus.
5.2.2 The direction of the reactions shall be parallel to the direction of the applied load at all times during the test.
5.2.3 The load shall be applied at a uniform rate and in such a manner as to avoid shock.
6.2.1 The directions of loads and reactions may be maintained parallel by judicious use of linkages, rocker bearings, and flexure
plates. Eccentricity of loading can be avoided by use of spherical bearings.apparatus shall be designed to incorporate the following
principles:
6.2.1.1 The distance between supports and points of load application shall remain constant for a given apparatus.
6.2.1.2 The direction of the reactions shall be parallel to the direction of the applied load at all times during the test.
6.2.1.3 The directions of loads and reactions may be maintained parallel by judicious use of linkages, rocker bearings, and
flexure plates. Eccentricity of loading can be avoided by use of spherical bearings.
6.2.1.4 The steel plate and bed of testing machine shall be of sufficient hardness and size to support the testing apparatus.
6.3 Drying Oven—Conforming to the requirements of Test Methods D2216.
6.4 Measuring Device—A measuring device suitable for measuring the width and depth of test specimens to the nearest 0.01
in. [0.25 mm].
7. Test Specimens
7.1 The standard test specimens shall beare typically beams 3 by 3 by 11 ⁄4 in. [76 by 76 by 290 mm], but mm] as described
in D1632. However, a similar test method may be used for testing specimens of other sizes. Test the specimens on their sides with
respect to their molded position.
7.2 Make flexural tests of moist cured specimens as soon as practicable after removing them from the moist room, and during
the period between removal from the moist room and testing keep the specimens moist by a wet burlap or blanket covering. Curing
and conditioning procedures shall be given in detail in the report.
...