1、Designation: D7760 18Standard Test Method forMeasurement of Hydraulic Conductivity of Materials Derivedfrom Scrap Tires Using a Rigid Wall Permeameter1This standard is issued under the fixed designation D7760; the number immediately following the designation indicates the year oforiginal adoption or
2、, in the case of revision, 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 test method covers laboratory measurement of thehydraulic conductivity (al
3、so referred to as coeffcient of per-meability) of water-saturated samples obtained from materialsderived from scrap tires using a rigid-wall permeameter. Thescrap tire materials covered in this method include tire chips,tire shreds, and tire derived aggregate (TDA) as described inPractice D6270 with
4、 particle sizes ranging from approximately12 to 305 mm. Whole scrap tires are not included in thisstandard. A clear trend between hydraulic conductivity andshred size has not been established at a given vertical pressurefor shreds 50 mm (1).21.2 A single- or dual-ring permeameter may be used in thet
5、ests. A dual-ring permeameter may be preferred over asingle-ring permeameter to take into account and preventshort-circuiting of permeant along the sidewalls of the per-meameter. The effects of sidewall flow is more significant athigh stresses and when the cell diameter is less than 6 times theparti
6、cle size (1).1.3 The test method is used under constant head conditions.1.4 Water is used as the permeant with the test method.1.5 Test Method D2434 also can be used for determinationof hydraulic conductivity of materials derived from scrap tireswith sizes smaller than 19 mm under constant head cond
7、itionsin a rigid-wall permeameter. Method D2434 includes the use ofa permeameter with a single ring.1.6 The values stated in SI units are to be regarded as thestandard. Hydraulic conductivity has traditionally been ex-pressed in cm/s in the US, even though the official SI unit forhydraulic conductiv
8、ity is m/s.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations p
9、rior to use.1.8 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization Technica
10、lBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3D653 Terminology Relating to Soil, Rock, and ContainedFluidsD2434 Test Method for Permeability of Granular Soils(Constant Head) (Withdrawn 2015)4D3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or
11、 Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4753 Guide for Evaluating, Selecting, and Specifying Bal-ances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingD6026 Practice for Using Significant Digits in GeotechnicalDataD6270 Practice for Use
12、of Scrap Tires in Civil EngineeringApplications3. Terminology3.1 Definitions:3.1.1 For common definitions of terms in this standard, referto Terminology D653.3.1.2 For definitions of terms related to scrap tires, refer toPractice D6270.3.1.3 hydraulic conductivity, k(also referred to as coeff-cient
13、of permeability or permeability) the rate of discharge of1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.14 on Geotechnics ofSustainable Construction.Current edition approved Jan. 1, 2018. Published February 2018.
14、Originallyapproved in 2012. Last previous edition approved in 2012 as D776012. DOI:10.1520/D776018.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at se
15、rviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
16、 PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organizatio
17、n Technical Barriers to Trade (TBT) Committee.1water under laminar flow conditions through a unit cross-sectional area of porous medium under a unit hydraulicgradient and standard temperature conditions (20 C).3.1.4 hydraulic gradient, ithe change in total head (headloss, h) per unit distance (L) in
18、 the direction of fluid flow, inwhich i = h/L.3.1.5 permeameterthe apparatus (cell) containing the testspecimen in a hydraulic conductivity test.4. Significance and Use4.1 This test method is used to measure one-dimensionalvertical flow of water through initially saturated samples ofmaterials derive
19、d from scrap tires under an applied hydraulicgradient. Hydraulic conductivity is required in various civilengineering applications of scrap tires.4.2 Samples are to be tested at a unit weight and under anoverburden pressure representative of field conditions. Datafrom the literature indicate a reduc
20、tion in hydraulic conductiv-ity with increasing vertical pressure (1).4.3 Use of a dual-ring permeameter is included in this testmethod in addition to a single-ring permeameter. The dual-ringpermeameter allows for minimizing potential adverse effects ofsidewall leakage on measured hydraulic conducti
21、vity of the testspecimens. The use of a bottom plate with an inner ring with adiameter smaller than the diameter of the permeameter and twooutflow ports (one from the inner ring, one from the annularspace between the inner ring and the permeameter) allows forseparating the flow from the central part
22、 of the test specimenfrom the flow near the sidewall of the permeameter.4.4 Darcys law is assumed to be valid, flow is assumed tobe laminar (Reynolds number less than approximately20003000), and the hydraulic conductivity is assumed to beessentially independent of hydraulic gradient. The validity of
23、Darcys law may be evaluated by measuring the hydraulicconductivity of a specimen at three hydraulic gradients. Thedischarge velocity (v = k i) is plotted against the appliedhydraulic gradient. If the resulting relationship is linear and themeasured hydraulic conductivity values are similar (i.e., wi
24、thin25 %), then Darcys law may be taken as valid.NOTE 1The quality of the result produced by this standard isdependent of the competence of the personnel using this standard and thesuitability of the equipment and facilities. Agencies that meet the criteriaof Practice D3740 are generally considered
25、capable of competent andobjective testing/sampling/inspection/etc. Users of this standard are cau-tioned that compliance with Practice D3740 does not in itself assurereliable results. Reliable results depend on many factors; Practice D3740provides a means of evaluating some of these factors.5. Appar
26、atus5.1 Schematics of the various components of two setupsused to determine hydraulic conductivity of samples of mate-rials derived from scrap tires using rigid-wall permeametersunder constant head conditions are provided for single-ring anddual-ring devices in Fig. 1(a) and (b), respectively.5.2 Co
27、nstant-Head Hydraulic SystemThe hydraulic sys-tem is used to apply, maintain, and measure heads and resultinghydraulic gradients in a test. The hydraulic system mainlyconsists of reservoirs that hold water and associated piping,tubing, valves, and connections. Pressure application setupsmay also be
28、used to pressurize influent and effluent liquids, inparticular to apply high hydraulic gradients. The system shallallow for maintaining constant hydraulic head to within 65%or better accuracy during a test. The system shall allow formeasurement of the constant head to within 65 % or betteraccuracy d
29、uring a test. The head shall be measured with agraduated pipette, engineers scale, pressure gauge, electronicpressure transducer, or any other device that has the resolutionrequired for the determination of head to the accuracy providedabove.5.2.1 System De-airingThe hydraulic system shall bedesigne
30、d to facilitate rapid and complete removal of free airbubbles from flow lines. This can be accomplished for exampleby using properly sized tubing and ball valves, and fittingswithout pipe threads. Properly sized components are smallenough to prevent entrapment of air bubbles, but are largeenough not
31、 to cause head losses as described in 6.1.5.3 Flow-Measurement SystemFlow-measurement systemis used to determine the amount of inflow and outflow from aspecimen during a test. The measurement device shall allowfor the measurement of the quantity of flow (both inflow andoutflow) over an interval of t
32、ime to within 65 % or betteraccuracy. Flow-measurement system may consist of a gradu-ated accumulator, Mariotte bottle, vertical standpipe in con-junction with an electronic pressure transducer, electromag-netic flow meter, or other volume-measuring device that hasthe resolution required to determin
33、e flow to the accuracyprovided above. In most cases, these devices are common tothe hydraulic system.5.3.1 De-airing and Dimensional Stability of the SystemThe flow-measurement system shall contain a minimum ofdead space and shall be equipped to allow for complete andrapid de-airing. Dimensional sta
34、bility of the system withrespect to changes in pressure shall be ensured by using a stiffflow-measurement system that includes glass pipe or rigidmetallic or thermoplastic tubing.5.4 Vertical Pressure Application SystemThe system forapplying vertical pressure on the test specimen in the per-meameter
35、 (if used) shall allow for applying and controlling thepressure to within 65 % or better accuracy. The verticalpressure application system may include a dead-weight loadapplication setup; a hydraulic load application system; or anyother system that allows for application of the desired level ofpress
36、ure to a specimen via the top of the specimen.5.5 PermeameterThe permeameter shall consist of a per-meameter cell and attached equipment that allow for connect-ing the permeameter to the hydraulic system, the flow-measurement system, and the pressure application system, aswell as provisions to suppo
37、rt a specimen and to permeate thespecimen. The permeameter cell shall consist of a rigid mold,cover plate, base plate, and attachments to hold the componentstogether without leakage during a test. The diameter of thepermeameter shall be determined based on the nominal size(defined as the average par
38、ticle size that comprises more than50 % of a sample per Practice D6270) of the scrap tire derivedmaterial to be tested. A permeameter diameter at least 6 timesD7760 182the nominal particle size has been shown to be adequate (1).Apermeameter with a diameter of 0.30 m and a height of 0.12 mwas demonst
39、rated to be effective for testing tire chips withdimensions of 38 76 mm (2).5.5.1 Rigid Permeameter MoldThe permeameter cellshall consist of a rigid-wall mold into which the tire specimento be tested is placed and in which the test specimen ispermeated. The mold shall be constructed of a rigid mater
40、ialsuch as steel, aluminum, brass, or plastic that will not bedamaged during placement/compression of the specimen in themold. The mold shall be cylindrical in shape. The cross-sectional area along the direction of flow shall not vary bymore than 62 % and the height shall not vary by more than61 %.
41、The permeameter shall be designed and operated suchFIG. 1 Example Test SetupsD7760 183that permeant water flows downward through the testspecimen, although upward flow may be used if the top of thespecimen is protected from upward movement by a rigidporous element. Provisions may be included along t
42、he sidewallof the permeameter to directly attach the mold to the constant-head hydraulic system or the flow-measurement system orboth. Hydraulic gradient measurements may be made using thestand pipe piezometer attachments on the sidewall.5.5.2 Top PlateThe top plate shall be constructed of arigid ma
43、terial that does not react adversely with the testmaterial or permeant water. The top plate may be sealed to therigid-wall permeameter cell using an O-ring or similar prevent-ing leakage or the plate may be perforated and not sealed to thepermeameter cell based on the design of the test setup.Aseale
44、dtop plate is used when the hydraulic or flow measurementsystems or both are connected to the top plate (or thepermeameter cell) through leak-proof ports or valves, whereasa perforated top plate is used when water is ponded directlyabove a specimen. The top plate shall be designed to ensurethat flow
45、 through the test specimen is one-dimensional.5.5.3 Base PlateThe bottom plate shall be constructed ofa rigid material that does not react adversely with the testmaterial or permeant water. The base plate shall be sealed tothe rigid-wall permeameter cell using an O-ring or similarpreventing leakage.
46、 The plate shall be designed to ensure thatflow through the test specimen is one-dimensional. If adual-ring permeameter is used, the diameter of the inner ringshall be 80 % of the diameter of the permeameter mold and theinner ring shall be concentric to the mold. The height of theinner ring shall be
47、 5 % of the height of the mold.5.5.4 Porous End PiecesThe specimen shall be overlainand underlain by porous end pieces. Porous end pieces shall beused to distribute water uniformly over the surfaces of a testspecimen (that is, areas perpendicular to the direction of flow).Porous end pieces shall be
48、constructed of a material that doesnot react with the specimen or the permeant liquid. Geosyn-thetic materials such as geonets and drainage geocompositesmay be used when high flow through the system is required.The end pieces shall have plane and smooth surfaces and befree of cracks, chips, and disc
49、ontinuities. The top porous endpiece shall have the same diameter (65 % or better accuracy)as the specimen, and shall have sufficient thickness to preventbreaking. If a dual-ring permeameter is used, two porous endpieces are required under the specimen due to the use of thedual-ring base plate. The first porous end piece with a circularshape shall have a diameter within -5 % of the diameter of theinner ring. The second porous end piece with a disc shape shallhave a width within -5 % of the width of the annular spacebetween the inner collector ring and
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