1、Designation: D6638 18Standard Test Method forDetermining Connection Strength Between GeosyntheticReinforcement and Segmental Concrete Units (ModularConcrete Blocks)1This standard is issued under the fixed designation D6638; the number immediately following the designation indicates the year oforigin
2、al adoption or, 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 is used to determine the connectionproperties be
3、tween a layer of geosynthetic reinforcement andsegmental concrete block units used in construction of rein-forced soil retaining walls. The test is carried out underconditions determined by the user that reproduce the connec-tion system at full scale. The results of a series of tests are usedto defi
4、ne a relationship between connection strength for asegmental unit-geosynthetic connection system and normalload.1.2 This is a performance test used to determine propertiesfor design of retaining wall systems utilizing segmental con-crete units and soil reinforcing geosynthetics, either geotextilesor
5、 geogrids. The test is performed on a full-scale constructionof the connection and may be run in a laboratory or the field.1.3 The values stated in SI units are regarded as thestandard. The values stated in inch-pound units are providedfor information only.1.4 This standard does not purport to addre
6、ss 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 prior to use.1.5 This international standard was develo
7、ped 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 TechnicalBarriers to Trade (TBT) Committee.2. Referenced Docum
8、ents2.1 ASTM Standards:2D448 Classification for Sizes of Aggregate for Road andBridge ConstructionD4354 Practice for Sampling of Geosynthetics and RolledErosion Control Products (RECPs) for TestingD4439 Terminology for GeosyntheticsD4495 Test Method for Impact Resistance of Poly(VinylChloride) (PVC)
9、 Rigid Profiles by Means of a FallingWeightD6637/D6637M Test Method for Determining Tensile Prop-erties of Geogrids by the Single or Multi-Rib TensileMethod3. Terminology3.1 Definitions:3.1.1 displacement criteria, na user-prescribed maximummovement, mm (in.), of the geosynthetic reinforcement outfr
10、om the back of segmental concrete units.3.1.2 geosynthetic, na planar product manufactured frompolymeric material used with soil, rock, earth, or other geo-technical engineering-related material as an integral part of amanmade project, structure, or system. D44393.1.3 granular infill, ncoarse-graine
11、d soil aggregate usedto fill the voids in and between segmental concrete units.3.1.4 peak connection strength, nthe maximum tensilecapacity of the connection between geosynthetic reinforcementand segmental concrete units.3.1.5 segmental concrete unit (modular concrete block),na concrete unit manufac
12、tured specifically for mortarless,dry-stack retaining wall construction.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.01 on Mechani-cal PropertiesCurrent edition approved July 15, 2018. Published August 2018. Or
13、iginallyapproved in 2001. Last previous edition approved in 2011 as D6638 11. DOI:10.1520/D6638-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Doc
14、ument Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on
15、Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.1.6 segmental concrete unit width, nthe segmental con-crete unit dimension parallel to the wall face and coincidentwith the geosy
16、nthetic reinforcement test specimen width.3.1.7 service-state connection strength, nthe connectiontensile capacity at a service-state displacement criterion be-tween geosynthetic reinforcement and segmental concreteunits.3.2 For definitions of other terms relating to geosynthetics,refer to Terminolo
17、gy D4439.4. Summary of Test Method4.1 One end of a wide geosynthetic reinforcement testspecimen is attached to dry-stacked segmental concrete blockunits assembled as specified by the user. The other end of thetest specimen is attached to a clamp, which is part of a constantrate of extension tensile
18、loading machine. The top course ofsegmental concrete block units is then loaded vertically to aconstant normal load, and the geosynthetic is then tensionedunder constant rate of displacement until a sustained loss ofconnection capacity or excessive movement (greater than150 mm) of the reinforcement
19、out from the connection, orboth.4.1.1 Peak connection capacity, and, when required, tensilecapacity after a user-prescribed displacement criteria hasoccurred, is used to define connection strength based on peakand, when required, service-state criteria, respectively. Boththese values may be obtained
20、 from each test that measuresgeosynthetic displacement. Tensile loads and strengths arereported per unit width of geosynthetic sample, kN/m (lb/ft).Generally, a series of tests is performed to establish a math-ematical relationship between connection strength and normalload on the connection.5. Sign
21、ificance and Use5.1 The connection strength between geosynthetic rein-forcement and segmental concrete block units is used in designof reinforced soil retaining walls.5.2 This test is used to determine the connection strength forthe design of the connection system formed by segmentalconcrete block u
22、nits and geosynthetic reinforcement layers inreinforced soil retaining walls. Performing a series of theseconnection tests at varying normal loads permits developmentof a relationship between connection strength and normal load.This relationship may be linear, bilinear, or some othercomplex mathemat
23、ical expression.5.3 This connection strength test is meant to be a perfor-mance test (laboratory or field); therefore, it should be con-ducted using full-scale system components. The conditions forthe test are selected by the user and are not for routine testing.5.4 As a performance test on full-sca
24、le system components,it accounts for some of the variables in construction proceduresand materials tolerance normally present for these types ofretaining wall systems.6. Apparatus6.1 Testing SystemAn example of a test apparatus andsetup is illustrated in Figs. 1 and 2. The principal componentsof the
25、 test apparatus are:6.1.1 Loading Frame.6.1.2 Normal Load Piston/Actuator.6.1.3 Vertical Loading Platen, with stiff rubber mat orairbag to apply uniform vertical pressure to top of concreteblocks.6.1.4 Vertical Load Cell, to measure normal load.6.1.5 Geosynthetic Loading Clamp.6.1.6 Horizontal Pisto
26、n/Actuator, to load geosynthetic rein-forcement in tension.6.1.7 Horizontal Load Cell, to measure geosynthetic tensileforce.6.1.8 Two (2) Horizontal Displacement MeasurementDevices, to record displacement of the geosynthetic at the backof the segmental concrete blocks.6.2 Loading FrameThe loading fr
27、ame shall have suffi-cient capacity to resist the forces developed by the horizontaland vertical loading pistons/actuators.6.3 Tensile Loading Clamp and Loading AssembliesThegeosynthetic is gripped at its free end with a clamp extendingthe full width of the specimen. The clamp shall be capable ofapp
28、lying a uniform force across the full width of the testspecimen. A roller grip assembly may be used to apply thetensile load. For some geosynthetics, it may be necessary toepoxy bond the geosynthetic to, or within, the clamp in orderto obtain a uniform stress distribution across the entire width oft
29、he test specimen.6.3.1 The tensile loading unit will generally be a constantrate of extension screw jack or hydraulic actuator that can beFIG. 1 Connection Strength Test SystemD6638 182displacement rate controlled. The loading equipment shall havea capacity that is at least equal to 120 % of the wid
30、e-striptensile strength of the geosynthetic (Test Method D4495 orD6637/D6637M) multiplied by the specimen width. The pistonshall be capable of at least 150 mm (6 in.) of movement inorder to facilitate test setup and to ensure that there is adequatestroke to achieve failure of geosynthetic reinforcem
31、ent speci-mens.NOTE 1Some systems (that is, modular concrete units with a depthgreater than 0.5 m) may need more than 150 mm of movement to achievefailure of the connection.6.3.2 The orientation of the tensioning force shall be hori-zontal and perpendicular to the back of the segmental units,and sha
32、ll be applied at the elevation where the geosyntheticexits the back of the segmental units.6.4 Load CellsA calibrated load cell shall be used tomeasure the tensile connection force and normal load duringthe test. The load cell used for measuring tension shall have acapacity that is greater than or e
33、qual to 120 % of the wide-striptensile strength of the geosynthetic (Test Method D4495 orD6637/D6637M) multiplied by the specimen width. The loadcell used for measuring the normal surcharge load shall have acapacity that is greater than or equal to 100 % of the maximumanticipated normal load. The lo
34、ad cells shall be accurate towithin 60.5 % of its full-scale range.6.5 Displacement Measuring DevicesTwo linear variabledisplacement transducers (LVDTs) or similar electronic dis-placement measuring devices are recommended to continu-ously monitor the displacement of the geosynthetic out fromthe bac
35、k of the concrete units. Alternatively, dial gauges maybe read and recorded manually at regular intervals not greaterthan 1 min. LVDTs, dial gauges, or similar measuring devicesshall be accurate to 60.1 mm (60.005 in.).7. Sampling7.1 Segmental Concrete Units:7.1.1 Segmental concrete units shall be f
36、ull-size blocks andmeet the manufacturers material and dimensional specifica-tions. Model or prototype units shall not be used unless it canbe demonstrated that they are equivalent to production units.7.1.2 The user shall specify or collect (or both) a sufficientsample of representative segmental un
37、its, from a standardproduction lot, to construct the anticipated number of testconfigurations for the connection system within the testingagencys load frame and testing system.7.1.3 The wall for connection testing shall be constructedusing randomly selected full-size (that is, full-width) segmentalu
38、nits from the users sampling of a standard production lot; see7.1.2. A maximum of two half-width segmental concrete unitsmay be used on only one course of the units being tested in aconfined width test apparatus. Segmental concrete units may bereused in testing if there is no cracking, abrasion, or
39、wearing ofthe concrete surfaces between tests.7.1.4 Wall WidthThe wall for testing shall be constructedto a minimum of 750 mm (29.5 in.) in width and contain atleast one typical segmental concrete unit running bond joint.The segmental wall width for testing shall be at least as wideas the geosynthet
40、ic test specimen width (see 7.2.3). Testing ofsegmental concrete unit widths greater than 500 mm may berepresented in this test by limiting the test wall to 1000 mm(39.4 in.) in width.NOTE 2Narrower wall widths may be used for testing, provided theFIG. 2 Connection Test Apparatus (Plan View)D6638 18
41、3connection strength is proven to be unaffected by this reduction (see7.2.3).7.1.5 ConditioningThe segmental concrete unit test speci-men shall be brought to standard temperature and relativehumidity conditions for testing in a laboratory. The temperatureis to be 21 6 2 C (70 6 4 F) and the relative
42、 humidity 65 610 %. For field testing, the specimen shall be brought toambient conditions for not less than 1 h. The temperature andhumidity at the start and end of the test shall be recorded forfield testing.7.2 Geosynthetic:7.2.1 Sampling RequirementsThe latest version of ASTMsampling protocol for
43、 geotextiles (Practice D4354) shall beused for the geosynthetic reinforcement material.7.2.2 ConditioningThe geosynthetic reinforcement testspecimen shall be brought to standard temperature and relativehumidity conditions for testing in a laboratory. The temperatureis to be 21 6 2 C (70 6 4 F) and t
44、he relative humidity 60 610 %. For field testing, the specimen shall be brought toambient conditions for not less than 1 h. The temperature andhumidity at the start and end of the test shall be recorded forfield testing.7.2.3 Specimen WidthThe geosynthetic reinforcement testspecimen shall be a minim
45、um of 750 mm (29.5 in.) in width.For tests that use two or more full segmental retaining wallunits on the bottom course, the geosynthetic shall be an exactmultiple of the segmental retaining wall unit width totalingclosest to but exceeding 750 mm (29.5 in.) in width. Forsegmental retaining wall unit
46、 widths greater than 500 mm(19.7 in.), a geosynthetic specimen width of 1000 mm(39.4 in.) may be used.NOTE 3Narrower geosynthetic reinforcement specimen widths maybe used for a specific concrete unit, provided that sufficient testingdemonstrates that narrower samples provide an evaluation of connect
47、ionperformance that is equivalent to the minimum 750 mm (29.5 in.) widthsample. This procedure may be appropriate for wall connections that areprimarily mechanical (non-frictional) in nature.7.2.4 Specimen LengthThe geosynthetic specimen shallhave sufficient length to cover the interface surface as
48、specifiedby the user. The specimen must be trimmed to providesufficient anchorage at the geosynthetic loading clamp and afree length between the back of the concrete blocks and loadingclamp ranging from a minimum of 200 mm (7.9 in.) to amaximum of 600 mm (23.6 in.). The geosynthetic reinforce-ment s
49、pecimen shall be placed between the stacked segmentalconcrete units to cover the same area that will be used in fieldconstruction of the connection, or as determined by the user.7.2.5 A new geosynthetic reinforcement test specimen shallbe used for each test.7.2.6 Number of TestsA sufficient number of tests shall beconducted to adequately define a relationship between connec-tion strength and normal load applied to the connection. Testsshall be conducted at a minimum of five (5) unique normalloads within the range of loads typical of wall design, asdire
