1、Designation: D7760 12Standard Test Method forMeasurement of Hydraulic Conductivity of Tire DerivedAggregates 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, in the ca
2、se 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 (also referred
3、 to as coeffcient of per-meability) of water-saturated tired derived aggregates (TDA)obtained from scrap tires using a rigid-wall permeameter. Thetire materials covered in this method include tire chips, tireshreds, and tire derived aggregate (TDA) as described inPractice D6270 with particle sizes r
4、anging 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 thetests. A dual-rin
5、g 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 theparticle size (1).1.3
6、 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 TDAs with sizes smaller than 19mm under constant head conditions in a rigid-wall permeame-ter. Method D2
7、434 includes the use of a permeameter with asingle ring.1.6 The standard units for the hydraulic conductivity valuesare the SI units, unless other units are specified. Hydraulicconductivity has traditionally been expressed in cm/s in theU.S., even though the official SI unit for hydraulic conductivi
8、tyis 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Ref
9、erenced Documents2.1 ASTM Standards:3D653 Terminology Relating to Soil, Rock, and ContainedFluidsD2434 Test Method for Permeability of Granular Soils(Constant Head)D3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design a
10、nd 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 of Scrap Tires in Civil EngineeringApplications3. Terminolo
11、gy3.1 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 D6270.3.2 Definitions of Terms Specific to This Standard:3.2.1 hydraulic conductivity, k(also referred to as coeff-cient of perme
12、ability or permeability) the rate of discharge ofwater under laminar flow conditions through a unit cross-sectional area of porous medium under a unit hydraulicgradient and standard temperature conditions (20 C).3.2.2 hydraulic gradient, ithe change in total head (headloss, Dh) per unit distance (L)
13、 in the direction of fluid flow, inwhich i = Dh/L.3.2.3 permeameterthe apparatus (cell) containing the testspecimen in a hydraulic conductivity test.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.14 on Geotechnics
14、 ofSustainable Construction.Current edition approved June 1, 2012. Published August 2012. DOI: 10.1520/D7760122The 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 Se
15、rvice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Significance and Use4.1 This test method
16、 is used to measure one-dimensionalvertical flow of water through initially saturated TDAs underan applied hydraulic gradient. Hydraulic conductivity is re-quired in various civil engineering applications of TDAs.4.2 TDAs are to be tested at a unit weight and under anoverburden pressure representati
17、ve of field conditions. Datafrom the literature indicate a reduction 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 a
18、dverse effects ofsidewall leakage on measured hydraulic conductivity 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
19、permeameter) allows forseparating the flow from the central part 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
20、beessentially independent of hydraulic gradient. The validity ofDarcys 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
21、 themeasured hydraulic conductivity values are similar (i.e., within25 %), 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 t
22、hat meet the criteriaof Practice D3740 are generally considered 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 D3
23、740provides a means of evaluating some of these factors.5. Apparatus5.1 Schematics of the various components of two setupsused to determine hydraulic conductivity of TDAs usingrigid-wall permeameters under constant head conditions areprovided for single-ring and dual-ring devices in Fig. 1(a) and(b)
24、, respectively.5.2 Constant-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 applicati
25、on setupsmay also be 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
26、% or betteraccuracy during 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 s
27、ystem shall bedesigned 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, bu
28、t are largeenough not 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)
29、over an interval of time 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
30、 required to determine 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-ai
31、ring. Dimensional stability 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 TDA specimen
32、 in the per-meameter (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 d
33、esired level ofpressure 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
34、 provisions to support 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(define
35、d as the average particle size that comprises more than50 % of a TDA sample per Practice D6270) of the TDA to betested. A permeameter diameter at least 6 times the nominalparticle size has been shown to be adequate (1).Apermeameterwith a diameter of 0.30 m and a height of 0.12 m wasdemonstrated to b
36、e effective for testing tire chips with dimen-sions 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 materialsuch
37、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 byD7760 122more than 62 % and the height shall not vary by more than61 %.
38、 The permeameter shall be designed and operated suchthat permeant water flows downward through the test speci-men, 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 the sidewallof the permeameter to
39、 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 material that does not react adver
40、sely 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.AsealedFIG. 1 Example Test SetupsD7760
41、 123top 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 f
42、low 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 leaka
43、ge. 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
44、 be 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
45、be 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 d
46、iscontinuities. 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. T
47、he 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 the permeameter mold.The end pieces sha
48、ll be free from clogging. The hydraulicconductivity of the porous end pieces shall be significantlygreater than that of the specimen to be tested. The requirementsoutlined in 6.1 below ensure that this criterion is satisfied.5.6 Deformation MeasurementThe permeameter may beequipped for determination
49、 of axial deformation of a specimenduring placement or during a test. The deformation of aspecimen shall be determined to the nearest 1 mm. The heightof a specimen may be monitored by direct observation throughthe cell wall using a cathetometer, camera setup, or otherinstrument that has the resolution required for the determina-tion of deformation as prescribed above. The height of aspecimen also may be monitored using a deformation gaugeconnected to the top plate above a specimen or a deformationgauge attached to a loading piston connected to the top pla
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