1、Designation: D7762 11D7762 18Standard Practice forDesign of Stabilization of Soil and Soil-Like Materials withSelf-Cementing Fly Ash1This standard is issued under the fixed designation D7762; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guidepractice covers procedures for the design of stabilization of soil and soil-like materi
3、als using self-cementing coalfly ash for roadway applications, treatment of expansive subgrade or organic subgrade, and limiting settlement of fills belowbuildings. The coal fly ash covered in this method includes self-cementing fly ashes described in Specification D5239.1.2 The testing and engineer
4、ing practices for self-cementing coal fly ash are similar to generally accepted practices for soilstabilization with fly ash and other pozzolans that require lime.1.3 The test methods in this guidepractice are applicable to the characterization of mechanical properties of in situ mixedself-cementing
5、 fly ash stabilized materials. Follow Practice D75 for sampling purposes. There are other related fly ash stabilizationstandards. Practice D5239 can be used to characterize the general types of fly ash for use in soil stabilization. Specification C593can be used to evaluate the performance of fly as
6、h and other pozzolans that require lime soil stabilization. Guide E2277 can beused to characterize properties of fly ash and bottom ash in structural fills and related design and construction considerations.1.4 The standard units are the SI units, unless other units are specified.1.5 This standard d
7、oes not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.6 Thi
8、s guide offers an organized collection of information or a series of options and does not recommend a specific courseof action. practice offers a set of instructions for performing one or more specific operations. This document cannot replaceeducation or experience and should be used in conjunction
9、with professional judgment. Not all aspects of this guidepractice maybe applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which theadequacy of a given professional service must be judged, nor should this document be applied without co
10、nsideration of a projectsmany unique aspects. The word “Standard” in the title of this document means only that the document has been approved throughthe ASTM consensus process.1.7 This international standard was developed in accordance with internationally recognized principles on standardizationes
11、tablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C593 Specification for Fly Ash and Other Pozzolans for Use W
12、ith Lime for Soil StabilizationC597 Test Method for Pulse Velocity Through ConcreteD75 Practice for Sampling AggregatesD420 Guide to Site Characterization for Engineering Design and Construction Purposes (Withdrawn 2011)3D653 Terminology Relating to Soil, Rock, and Contained FluidsD698 Test Methods
13、for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft3 (600 kN-m/m3)1 This practice is under the jurisdiction ofASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.14 on Geotechnics of SustainableConstruction.Current edition ap
14、proved Dec. 1, 2011Jan. 1, 2018. Published January 2012February 2018. Originally approved in 2011. Last previous edition approved in 2011 asD776211. DOI: 10.1520/D7762-1110.1520/D7762-182 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceast
15、m.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.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. Becaus
16、eit 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 versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Bar
17、r Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D1557 Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3 (2,700kN-m/m3)D1883 Test Method for California Bearing Ratio (CBR) of Laboratory-Compacted SoilsD4609 Guide for E
18、valuating Effectiveness of Admixtures for Soil Stabilization (Withdrawn 2017)3D5102 Test Methods for Unconfined Compressive Strength of Compacted Soil-Lime MixturesD5239 Practice for Characterizing Fly Ash for Use in Soil StabilizationD5759 Guide for Characterization of Coal Fly Ash and Clean Coal C
19、ombustion Fly Ash for Potential UsesD5918 Test Methods for Frost Heave and Thaw Weakening Susceptibility of SoilsE2201 Terminology for Coal Combustion ProductsE2277 Guide for Design and Construction of Coal Ash Structural Fills2.2 AASHTO (American Association of State Highway and Transportation Offc
20、ials) Standard:4AASHTO T 307 Standard Method of Test for Determining the Resilient Modulus of Soils and Aggregate Materials2.3 TRB (Transportation Research Board) Standard:5NCHRP 1-28A Harmonized Test Method for Laboratory Determination of Resilient Modulus for Flexible Pavement Design2.4 ACAA (Amer
21、ican Coal Ash Association) Soil Stabilization Manual:6Soil Stabilization and Pavement Recycling with Self-Cementing Coal Fly Ash3. Terminology3.1 Definitions:3.1.1 For definitions related to Coal Combustion Productions, see coal combustion products, refer to Terminology E2201. Fordefinitions related
22、 to geotechnical properties, see of common technical terms in this standard, refer to Terminology D653.4. Significance and Use4.1 Self-cementing coal fly ashes are suitable materials for the stabilization of soils, recycled pavement materials and roadsurface gravel. Fly ash stabilization can result
23、in improved properties, including increased stiffness, strength and freeze-thawdurability; reduced hydraulic conductivity, plasticity, and swelling; and increased control of soil compressibility and moisture. Flyash stabilized materials (FASM) may be used in roadway construction, such as working pla
24、tforms during construction, stabilizedsubgrade, subbase, and base layers. Fly ash stabilization can also be used in limiting settlement of fills below buildings.4.2 This guidepractice is intended for use with self-cementing fly ash that can be used separatelyindividually or along with otherstabilizi
25、ng admixtures to improve soil properties.4.3 The guidepractice describes the unique design considerations that may apply to stabilization of soils and soil-like materialswith self-cementing coal fly ash. The requirements for stabilization of specific materials may vary due to local conditions or the
26、intended use of the stabilized material, or both.4.3.1 This guidepractice is not intended to limit the flexibility of design in stabilization. The degree of success attained instabilization with coal fly ash is highly dependent on the particular combination of soil, fly ash, and other additives and
27、theconstruction procedure used. The selection of appropriate materials, applicable tests, acceptance criteria, and specification is theresponsibility of the design engineer.4.4 The test methods in this guidepractice are intended for the determination of mechanical properties of FASM. Thecharacteriza
28、tion of mechanical property improvement with self-cementing fly ash will assist in the evaluation of the fly ashstabilized materials.4.5 The use of self-cementing fly ash in geotechnical engineering applicationapplications may be regulated by state and localcodes. The codes should be consulted.5. St
29、abilization Applications5.1 GeneralHigh calcium oxide content and self-cementing properties of subbituminous coal fly ash (self-cementing fly ash)can be used effectively in stabilization, such as drying wet soils to facilitate compaction and increase subgrade support, improvingstiffness and strength
30、 and reducing compressibility of both cohesive soils and granular materials. However, the effectivenessdepends on specific material to be stabilized and specific fly ash and has to be determined on a case-specific basis.5.2 Stabilization of Fine-Grained SoilsIn the fly ash stabilization of fine-grai
31、ned soils, flocculation, agglomeration, andcementitious reactions may occur. Self-cementing coal fly ash has been demonstrated to be an effective stabilization agent for arange of fine-grained soils in increasing subgrade support capacity for pavements, in reducing swelling potential of expansive so
32、ils,3 The last approved version of this historical standard is referenced on www.astm.org.4 Available from American Association of State Highway and Transportation Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,http:/www.transportation.org.5 National Cooperative Highway
33、Research Program, Transportation Research Board, Washington, DC.6 American Coal Ash Association Educational Foundation, 15200 E. Girard Ave., Suite 3050, Aurora, Colorado 80014-3955.D7762 182in increasing shear strength of organic soils and fine-grained soils, and in reducing the compressibility of
34、fills under foundations.The fly ash stabilized section also provides a more stable platform (working platform) during pavement construction over very softsubgrades. Such stabilized subgrade working platforms can be treated as a subbase section in the pavement thickness design.5.3 Stabilization of Co
35、arse-Grained MaterialsIn coarse-grained materials, such as aggregate base, gravels, recycled pavementmaterials, recycled road surface gravel, cementation through pozzolanic reactions and hydration within the self-cementing coal flyash can cause strength gain and enhance durability. The reaction rate
36、 depends on the self-cementing coal fly ash used.5.4 Pavement Recycling: Full Depth ReclamationRecycling or reclaiming existing flexible pavements with self-cementing flyash as a stabilizing agent has been demonstrated to be an efficient and economical method of pavement rehabilitation for roadways.
37、The process is accomplished by pulverizing the entire pavement section down to the subgrade and stabilizing the pulverizedmixture by adding self-cementing coal fly ash and water (as needed). The recycled section provides an enhanced base for a newhot mix asphalt (HMA) wearing surface. Self-cementing
38、 fly ash stabilized recycled sections have structural capacities (enhancedmodulus and reduced plastic deformations), which are considerably better than a crushed-stone aggregate base and can beequivalent to an asphaltic concrete base section.5.5 Gravel Road Recycling: In Situ ReclamationRecycling or
39、 reclaiming existing road surface gravel (RSG) withself-cementing fly ash stabilization is an economical method for converting gravel roads to paved roads. The process isaccomplished by placing the appropriate amount of self-cementing fly ash over the entire road surface and then blending it intothe
40、 RSG down to the required depth to form a base for the HMA layer. The self-cementing fly ash stabilized-RSG has similar orbetter properties as a high-quality crushed aggregate base course in the stabilized section. The recycled and stabilized RSG sectionprovides an enhanced base for a new HMA wearin
41、g surface.6. Laboratory Mix-Design6.1 GeneralA laboratory mix design is developed to establish the optimum fly ash content, optimum moisture content,maximum dry density, and maximum strength gain for design and construction testing purposes. Since most stabilizationapplications with self-cementing f
42、ly ash rely on the fly ash as stabilizing agent, the test and design procedures should address therapid rate at which the fly ash hydrates upon exposure to water.Ash hydration can significantly alter the compaction characteristicsof materials treated with self-cementing fly ash.6.2 Hydration RateSel
43、f-cementing ash hydrates at a much more rapid rate than Portland cement, a 2-h delay in compactionmay decrease the maximum density and reduce strength. A 1- to 2-h compaction delay should be achievable in situ and should bestated in the project specifications. The specified maximum compaction delay
44、time in the project specification is measured fromthe time the self-cementing fly ash is incorporated into the materials being stabilized and has been exposed to water. Laboratorytests conducted to establish construction and design parameters should be based on the properties of the stabilized mater
45、ialscompacted at the specified maximum allowable delay time.6.3 Moisture Content for StabilizationFor a given compactive energy, an optimum moisture content exists at which maximumstrength is achieved. This optimum moisture content for maximum strength is generally 1 to 8 % below optimum moisture co
46、ntentfor maximum density, depending on mineralogy of the self-cementing fly ash and the type of material being stabilized.Construction specifications that specify moisture ranges based solely upon compaction characteristics can produce stabilizedmaterials having strengths 50 % or less of the maximum
47、 potential strength, greatly reducing the benefits achieved through thestabilization operation. The allowable range in moisture content must be specified and monitored during construction to ensure thatthe moisture content of the stabilized section is near the optimum maximum strength.6.4 Mix Design
48、 ProcedureThe procedure herein follows ACAA manual, Soil Stabilization and Pavement Recycling withSelf-Cementing Coal Fly Ash, for determining moisture-density and moisture-strength relationships of the fly ash stabilizedmaterials. Standard size compaction molds with a diameter of 100 mm (4 in.) or
49、150 mm (6 in.) depending on maximum particlesize of the material to be stabilized can be used with standard Proctor (Test Method D698) or modified Proctor (Test MethodD1557) compactive energy. Use of split molds (metal or polyvinyl chloride reinforced with clamps) is desirable for the ease ofspecimen removal after compaction. After blending of the soil, fly ash, and water, specimens are compacted using the specifiedcompaction delay. A minimum of five test specimens, compacted over a wide range of moisture contents, should be prepared foreach test series to define both
