ASTM D6276-19

Standard Test Method for Using pH to Estimate the Soil-Lime Proportion Requirement for Soil Stabilization

SIGNIFICANCE AND USE
5.1 The soil-lime pH test is performed as a test to indicate the soil-lime proportion needed to maintain the elevated pH necessary for sustaining the reactions required to stabilize a soil. The test derives from Eades and Grim.4  
5.2 Performance tests are normally conducted in a laboratory to verify the results of this test method.  
5.3 This test method will not provide reliable information relative to the potential reactivity of a particular soil, nor will it provide information on the magnitude of increased strength to be realized upon treatment of this soil with the indicated percentage of lime.  
5.4 This test method can be used to estimate the percentage of lime as hydrated lime or quicklime needed to produce a lime stabilized soil. Common candidate soils contain clay minerals and have a Plasticity Index ≥10.  
5.5 Agricultural lime (crushed limestone) will not stabilize soil.
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 provides a means for estimating the soil-lime proportion requirement for stabilization of a soil. This test method is performed on soil passing the 425μm (No. 40) sieve. The optimum soil-lime proportion for soil stabilization is determined by tests of specific characteristics of stabilized soil such as unconfined compressive strength or plasticity index.  
1.2 Some highly alkaline by-products (lime kiln dust, cement kiln dust, carbide lime, and so forth) have been successfully used to stabilize soil. This test method is not intended for these materials and any such product would need to be tested for specific characteristics as indicated in 1.1.  
1.3 This test method is used to determine the percentage of lime that results in a soil-lime pH of approximately 12.4.
Note 1: Under ideal laboratory conditions of 25°C and sea level elevation, the pH of the lime-soil-water solution should be 12.4.  
1.4 Lime is not an effective stabilizing agent for all soils. Some soil components such as sulfates, phosphates, organics, and iron can adversely affect soil-lime reactions and may produce erroneous results using this test method.  
1.5 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.6 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.  
1.6.1 The procedures used to specify how data are collected/ recorded and calculated in the standard are regarded as the 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 these test methods to consider significant digits used in analysis for engineering data.  
1.7 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.  
1.8 This international standard was developed in accordance with internationally recognized principles on st...

General Information

• Status: Published
• Publication Date: 31-Jan-2019
• ICS: 13.080.99 - Other standards related to soil quality
• Technical Committee: D18 - Soil and Rock
• Drafting Committee: D18.15 - Stabilization With Admixtures

Relations

• Replaces: ASTM D6276-99a(2006)e1 - Standard Test Method for Using pH to Estimate the Soil-Lime Proportion Requirement for Soil Stabilization (Withdrawn 2015)
• Effective Date: 01-Feb-2019
• Refers: ASTM D4753-24 - Standard Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and Construction Materials Testing
• Effective Date: 01-Feb-2024
• 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 C977-18 - Standard Specification for Quicklime and Hydrated Lime for Soil Stabilization
• Effective Date: 01-Oct-2018
• Refers: ASTM D4753-15 - Standard Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and Construction Materials Testing
• Effective Date: 01-May-2015
• Refers: ASTM D653-14 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Aug-2014
• Refers: ASTM E11-13 - Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves
• Effective Date: 01-Oct-2013
• 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 D1293-12 - Standard Test Methods for pH of Water
• Effective Date: 01-Jan-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 C977-10 - Standard Specification for Quicklime and Hydrated Lime for Soil Stabilization
• Effective Date: 01-Nov-2010

Overview

ASTM D6276-19: Standard Test Method for Using pH to Estimate the Soil-Lime Proportion Requirement for Soil Stabilization outlines a laboratory procedure to estimate the amount of lime needed to stabilize soil by monitoring pH levels. Soil stabilization using lime is a common civil engineering practice to improve soil properties such as strength and durability, particularly in clayey soils. This standard provides a quick and effective method for estimating lime requirements, facilitating the planning and design of construction projects involving soil treatment.

Key Topics

• Estimation of Soil-Lime Proportion: The test method determines the percentage of lime (as hydrated lime or quicklime) required to achieve a soil-lime mixture with a pH of approximately 12.4, which is critical for effective stabilization.
• Suitability of Soils: The method is most applicable to soils containing clay minerals with a Plasticity Index of 10 or greater. It is not suitable for all soil types, as some components (such as organics, iron, phosphates, sulfates) can interfere with lime reactions.
• Use of Lime Types: Only hydrated lime or quicklime is effective for stabilization under this method; agricultural lime (crushed limestone) will not stabilize soil.
• Laboratory Procedure: Soil samples passing a 425μm (No. 40) sieve are tested. Multiple soil-lime mixtures are prepared with varying lime content, and their pH is measured to determine the optimal lime percentage.
• Significance of pH: Maintaining a high pH (around 12.4) is necessary to ensure pozzolanic reactions that improve soil strength and stability.
• Limitations: This method does not assess the final strength or specific reactivity of the soil, and further performance tests are advised. It is also not designed for highly alkaline industrial by-products like kiln dusts.

Applications

• Road Construction and Civil Engineering: Estimating the correct lime proportion for soil stabilization is vital for road bases, embankments, and foundation works, especially in projects that involve clayey or expansive soils.
• Geotechnical Investigation: The pH-based estimation is used in preliminary site investigations to guide laboratory or field stabilization trials.
• Quality Control: The method provides a standardized approach for project engineers and laboratory personnel to ensure consistent and efficient stabilization practices.
• Specification Compliance: By adhering to ASTM D6276, construction and engineering projects can demonstrate compliance with internationally recognized standards.

Related Standards

• ASTM C977: Specification for Quicklime and Hydrated Lime for Soil Stabilization - Requirements for the lime materials used in soil stabilization.
• ASTM D653: Terminology Relating to Soil, Rock, and Contained Fluids - Definitions of terms relevant to soil testing.
• ASTM D1193: Specification for Reagent Water - Quality of water used in testing.
• ASTM D1293: Test Methods for pH of Water - Calibration and measurement procedures for pH.
• ASTM D2216: Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock - Prepares samples for testing.
• ASTM D3740: Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock.
• ASTM D6026: Practice for Using Significant Digits in Geotechnical Data - Methods for recording and reporting results.

Practical Value

Using ASTM D6276-19 allows construction teams and geotechnical engineers to:

• Quickly estimate lime requirements for soil stabilization, saving time in the project design phase.
• Ensure effective soil-lime reactions by targeting the appropriate pH, ultimately enhancing soil load-bearing capacity and durability.
• Maintain adherence to international best practices, supporting quality assurance and regulatory compliance in infrastructure projects.

For optimal results, users should follow ASTM D6276 procedures accurately, rely on competent laboratory personnel, and consult related standards for comprehensive soil-lime stabilization processes.

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: D6276 − 19
Standard Test Method for
Using pH to Estimate the Soil-Lime Proportion Requirement
for Soil Stabilization
This standard is issued under the fixed designation D6276; 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* increase or reduce significant digits of reported data to be
commensuratewiththeseconsiderations.Itisbeyondthescope
1.1 This test method provides a means for estimating the
of these test methods to consider significant digits used in
soil-limeproportionrequirementforstabilizationofasoil.This
analysis for engineering data.
test method is performed on soil passing the 425µm (No. 40)
1.7 This standard does not purport to address all of the
sieve.Theoptimumsoil-limeproportionforsoilstabilizationis
safety concerns, if any, associated with its use. It is the
determined by tests of specific characteristics of stabilized soil
responsibility of the user of this standard to establish appro-
such as unconfined compressive strength or plasticity index.
priate safety, health, and environmental practices and deter-
1.2 Some highly alkaline by-products (lime kiln dust, ce-
mine the applicability of regulatory limitations prior to use.
ment kiln dust, carbide lime, and so forth) have been success-
1.8 This international standard was developed in accor-
fully used to stabilize soil. This test method is not intended for
dance with internationally recognized principles on standard-
these materials and any such product would need to be tested
ization established in the Decision on Principles for the
for specific characteristics as indicated in 1.1.
Development of International Standards, Guides and Recom-
1.3 This test method is used to determine the percentage of
mendations issued by the World Trade Organization Technical
lime that results in a soil-lime pH of approximately 12.4.
Barriers to Trade (TBT) Committee.
NOTE 1—Under ideal laboratory conditions of 25°C and sea level
elevation, the pH of the lime-soil-water solution should be 12.4. 2. Referenced Documents
1.4 Lime is not an effective stabilizing agent for all soils. 2.1 ASTM Standards:
Some soil components such as sulfates, phosphates, organics,
C977 Specification for Quicklime and Hydrated Lime for
and iron can adversely affect soil-lime reactions and may Soil Stabilization
produce erroneous results using this test method.
D421 Practice for Dry Preparation of Soil Samples for
Particle-Size Analysis and Determination of Soil Con-
1.5 Units—The values stated in SI units are to be regarded
stants (Withdrawn 2016)
as standard. No other units of measurement are included in this
D653 Terminology Relating to Soil, Rock, and Contained
standard.
Fluids
1.6 All observed and calculated values shall conform to the
D1193 Specification for Reagent Water
guidelines for significant digits and rounding established in
D1293 Test Methods for pH of Water
Practice D6026.
D2216 Test Methods for Laboratory Determination of Water
1.6.1 Theproceduresusedtospecifyhowdataarecollected/
(Moisture) Content of Soil and Rock by Mass
recorded and calculated in the standard are regarded as the
D3740 Practice for Minimum Requirements for Agencies
industry standard. In addition, they are representative of the
Engaged in Testing and/or Inspection of Soil and Rock as
significant digits that generally should be retained. The proce-
Used in Engineering Design and Construction
dures used do not consider material variation, purpose for
D4753 Guide for Evaluating, Selecting, and Specifying Bal-
obtaining the data, special purpose studies, or any consider-
ances and Standard Masses for Use in Soil, Rock, and
ations for the user’s objectives; and it is common practice to
Construction Materials Testing
Thistestmethodisunder the jurisdiction ofASTM CommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.15 on Stabilization With For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Admixtures. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Current edition approved Feb. 1, 2019. Published February 2019. Originally Standards volume information, refer to the standard’s Document Summary page on
approved in 1998. Last previous edition approved in 2006 as D6276 – 99a(2006), the ASTM website.
which was withdrawn July 2015 and reinstated in February 2019. DOI: 10.1520/ The last approved version of this historical standard is referenced on
D6276-19. www.astm.org.
*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
D6276 − 19
D6026 Practice for Using Significant Digits in Geotechnical 5.2 Performance tests are normally conducted in a labora-
Data tory to verify the results of this test method.
E11 Specification for Woven Wire Test Sieve Cloth and Test
5.3 This test method will not provide reliable information
Sieves
relative to the potential reactivity of a particular soil, nor will
it provide information on the magnitude of increased strength
3. Terminology
to be realized upon treatment of this soil with the indicated
3.1 Definitions:
percentage of lime.
3.2 For definitions of common technical terms used in this
5.4 This test method can be used to estimate the percentage
standard, refer to Terminology D653.
oflimeashydratedlimeorquicklimeneededtoproducealime
stabilized soil. Common candidate soils contain clay minerals
3.3 Definitions of Terms Specific to This Standard:
and have a Plasticity Index ≥10.
3.3.1 buffer solution, n—asolutionofspecificpHvalueused
to calibrate the pH meter.
5.5 Agricultural lime (crushed limestone) will not stabilize
soil.
3.3.2 free lime, n—lime in a soil-lime mixture that has not
dissociated into calcium and hydroxyl ions.
NOTE 2—The quality of the result produced by this standard is
dependent on the competence of the personnel performing it and the
3.3.3 hydrated lime, n—lime that is predominately calcium
suitability of the equipment and facilities used. Agencies that meet the
hydroxide (Ca(OH) ) or a mixture of calcium hydroxide and
criteria of Practice D3740 are generally considered capable of competent
magnesium oxide (MgO) or magnesium hydroxide
and objective testing/sampling/inspection/etc. Users of this standard are
(Mg(OH) ).
cautioned that compliance with Practice D3740 does not in itself assure
reliable results. Reliable results depend on many factors; Practice D3740
3.3.4 lime content, n—the ratio expressed as a percentage of
provides a means of evaluating some of those factors.
the mass of lime to the dry mass of soil.
3.3.5 lime stabilization, n—addition of lime to a soil in
6. Apparatus
sufficient quantities to promote long-term pozzolanic reactions
6.1 Balance or Scale—A balance or scale for determining
that result in strength gain and permanent improvement in
the mass of soil and lime having a minimum capacity of 600 g
stability.
and meeting the requirements of Specification D4753 for a
3.3.5.1 Discussion—Textural improvement alone, such as
balance or scale of 0.01 g readability.
reduced plasticity, is often referred to as “modification.”
6.2 Sieve—A 425µm (No. 40) sieve, conforming to the
Modification can be effected by lime addition rates less than
requirements of Specification E11.
those required for stabilization and may not be permanent.
6.3 Glass or Plastic Bottles—Six 150-mL(or larger) bottles
3.3.6 quicklime, n—lime that is predominately calcium ox-
with tight-fitting screw caps.
ide (CaO) or calcium oxide in association with magnesium
oxide (MgO).
6.4 pH Meter—A pH meter equipped with reference elec-
3.3.7 stabilization, n—a process to improve the engineering trode and low-sodium error glass pH-sensitive electrodes (or
combination electrode) and a meter capable of displaying 0.01
properties of soils at a site or in the laboratory.
units pH at 0.02 pH accuracy over a range from 0 to 14. The
4. Summary of Test Method meter must have a pH set-point of 12 or allow for “user
selectable” calibration.
4.1 A series of specimens is prepared containing a range of
percentages of lime content in soil. Measurements of pH are
NOTE 3—The electrode used with the pH meter should incorporate a
made on slurries of the specimens to determine the lime clog resistant junction designed for “dirty” suspended solids solutions to
prevent clogging.
content of the soil-lime mixture to obtain a pH of at least 12.4.
6.5 Drying Oven—Oven conforming to requirements of
4.2 The pH of at least 12.4 achieved in this test method
Specification D2216.
results from free lime remaining in the soil-lime mixture.
Normally, the pH of the specific lime being used for soil
6.6 Miscellaneous Equipment—An airtight, moisture-proof
stabilization should be determined and used as the indicator container for preserving the moisture content of the soil;
pH. mixing tools and scoops for use in preparing test specimens.
5. Significance and Use
7. Reagents and Materials
5.1 The soil-lime pH test is performed as a test to indicate 7.1 Water—Reference to water shall be understood to mean
the soil-lime proportion needed to maintain the elevated pH
Type II reagent water conforming to Specification D1193.
necessary for sustaining the reactions required to stabilize a Store the water in a tightly capped container; boil and cool the
soil. The test derives from Eades and Grim.
water immediately before use.
NOTE 4—If the pH of the site water to be used is highly acidic (<6) or
highly basic (>9) test results should be checked against a specimen made
Eades, J.L., and Grim, R.E.,AQuickTest to Determine Lime Requirements for
with the site water rather than Type II water.
Lime Stabilization, Highway Research Record No. 139, 1966, NationalAcademy of
7.2 Buffer Solution—Use a buffer solution having a pH of
Sciences, National Research Council, Highway Research Board, Washington, DC,
(pp. 61–72). 12, either commercially
...