1、Designation: D75/D75M 14 American Association StateHighway and TransportationOfficials StandardAASHTO No.: T2Standard Practice forSampling Aggregates1This standard is issued under the fixed designation D75/D75M; the number immediately following the designation indicates the yearof original adoption
2、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. Scope1.1 This practice covers sampling of coarse and fine aggre-gates for the followin
3、g purposes:1.1.1 Preliminary investigation of the potential source ofsupply,1.1.2 Control of the product at the source of supply,1.1.3 Control of the operations at the site of use, and1.1.4 Acceptance or rejection of the materials.NOTE 1Sampling plans and acceptance and control tests vary with thety
4、pe of construction in which the material is used.1.2 The text of this standard references notes and footnoteswhich provide explanatory material. These notes and footnotes(excluding those in tables and figures) shall not be consideredas requirements of the standard.1.3 The values stated in either SI
5、units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.4 This standard does
6、 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.NOTE 2The quality of the results prod
7、uced by this standard aredependent on the competence of the personnel performing the procedureand the capability, calibration, and maintenance of the equipment used.Agencies that meet the criteria of Practice D3666 are generally consideredcapable of competent and objective testing/sampling/inspectio
8、n/etc. Usersof this standard are cautioned that compliance with Practice D3666 alonedoes not completely assure reliable results. Reliable results depend onmany factors; following the suggestions of Practice D3666 or somesimilar acceptable guideline provides a means of evaluating and control-ling som
9、e of those factors.2. Referenced Documents2.1 ASTM Standards:2C125 Terminology Relating to Concrete and Concrete Ag-gregatesC702 Practice for Reducing Samples ofAggregate to TestingSizeD8 Terminology Relating to Materials for Roads and Pave-mentsD2234/D2234M Practice for Collection of a Gross Sample
10、of CoalD3665 Practice for Random Sampling of Construction Ma-terialsD3666 Specification for Minimum Requirements for Agen-cies Testing and Inspecting Road and Paving MaterialsE105 Practice for Probability Sampling of MaterialsE122 Practice for Calculating Sample Size to Estimate, WithSpecified Preci
11、sion, the Average for a Characteristic of aLot or ProcessE141 Practice for Acceptance of Evidence Based on theResults of Probability Sampling3. Terminology3.1 Definitions:3.1.1 maximum size of aggregate, nin specifications for,or descriptions of aggregatethe smallest sieve openingthrough which the e
12、ntire amount of aggregate is required topass.3.1.2 maximum aggregate size, (Superpave) nin specifi-cations for, or descriptions of aggregateone size larger thanthe nominal maximum aggregate size.3.1.3 nominal maximum aggregate size (of aggregate),nin specifications for, or descriptions of aggregatet
13、hesmallest sieve opening through which the entire amount of theaggregate is permitted to pass.3.1.4 nominal maximum aggregate size (Superpave), ninspecifications for, or descriptions of aggregateone size largerthan the first sieve that retains more than 10 % aggregate.1This practice is under the jur
14、isdiction of ASTM Committee D04 on Road andPaving Materials and is the direct responsibility of Subcommittee D04.30 onMethods of Sampling.Current edition approved June 1, 2014. Published June 2014. Originallyapproved in 1920. Last previous edition approved in 2009 as D75/D75M 09. DOI:10.1520/D0075_D
15、0075M-14.2For 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 Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive,
16、 PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.4.1 DiscussionThe definitions in 3.1.1 and 3.1.2 alsoappear in Terminologies C125 and D8. They are presented inthis standard to illustrate the differences between the aggregatedefinitions and Superpave definitions of similar terms. Th
17、edefinitions in 3.1.2 and 3.1.4 apply to hot mix asphalt (HMA)mixtures designed using the Superpave system only.3.1.4.2 DiscussionSpecifications on aggregates usuallystipulate a sieve opening through which all of the aggregatemay, but not need to, pass so that a slated maximum portion ofthe aggregat
18、e may be retained on that sieve.Asieve opening sodesigned is the nominal maximum size.4. Significance and Use4.1 Sampling is equally as important as the testing, and thesampler shall use every precaution to obtain samples that willshow the nature and condition of the materials which theyrepresent.4.
19、2 Samples for preliminary investigation tests are obtainedby the party responsible for development of the potentialsource (Note 3). Samples of materials for control of theproduction at the source or control of the work at the site of useare obtained by the manufacturer, contractor, or other partiesr
20、esponsible for accomplishing the work. Samples for tests to beused in acceptance or rejection decisions by the purchaser areobtained by the purchaser or his authorized representative.NOTE 3The preliminary investigation and sampling of potentialaggregate sources and types occupies a very important pl
21、ace in determin-ing the availability and suitability of the largest single constituent enteringinto the construction. It influences the type of construction from thestandpoint of economics and governs the necessary material control toensure durability of the resulting structure, from the aggregate s
22、tandpoint.This investigation should be done only by a responsible trained andexperienced person. For more comprehensive guidance, see theAppendix.5. Securing Samples5.1 GeneralWhere practicable, samples to be tested forquality shall be obtained from the finished product. Samplesfrom the finished pro
23、duct to be tested for abrasion loss shall notbe subject to further crushing or manual reduction in particlesize in preparation for the abrasion test unless the size of thefinished product is such that it requires further reduction fortesting purposes.5.2 InspectionThe material to be sampled shall be
24、 visuallyinspected to determine discernible variations. If any discerniblevariations are noted, corrective action shall be taken to estab-lish homogeneity in the material prior to sampling. If it isnecessary to indicate the degree of variability existing withinthe main pile, separate samples shall b
25、e drawn from separateareas of the pile. The seller shall provide suitable equipmentneeded for proper inspection and sampling.5.3 Procedure:5.3.1 Sampling from a Flowing Aggregate Stream (Bins orBelt Discharge)Select units to be sampled by a randommethod, such as Practice D3665, from the production.
26、Obtainat least three approximately equal increments, selected atrandom from the unit being sampled, and combine to form afield sample whose mass equals or exceeds the minimumrecommended in 5.4.2. Take each increment from the entirecross section of the material as it is being discharged. It isusually
27、 necessary to have a special device constructed for useat each particular plant. This device consists of a pan ofsufficient size to intercept the entire cross section of thedischarge stream and hold the required quantity of materialwithout overflowing. A set of rails may be necessary to supportthe p
28、an as it is passed under the discharge stream. Insofar as ispossible, keep bins continuously full or nearly full to reducesegregation.NOTE 4Sampling the initial discharge or the final few tons from a binor conveyor belt increases the chances of obtaining segregated materialand should be avoided.5.3.
29、2 Sampling from the Conveyor BeltSelect units to besampled by a random method, such as Practice D3665, fromthe production. Obtain at least three approximately equalincrements, selected at random, from the unit being sampledand combine to form a field sample whose mass equals orexceeds the minimum re
30、commended in 5.4.2. Stop the con-veyor belt while the sample increments are being obtained.Insert two templates, the shape of which conforms to the shapeof the belt in the aggregate stream on the belt, and space themsuch that the material contained between them will yield anincrement of the required
31、 weight (see Fig. 1). Carefully scoopall material between the templates into a suitable container andcollect the fines on the belt with a brush and dust pan and addto the container.NOTE 5Automatic belt samplers may be used as long as they areproperly maintained, and regular inspection ensures all ma
32、terial is beingremoved from the belt (see Fig. 2).5.3.3 Sampling from StockpilesAvoid sampling coarseaggregate or mixed coarse and fine aggregate from stockpileswhenever possible, particularly when the sampling is done forthe purpose of determining aggregate properties that may bedependent upon the
33、grading of the sample. If circumstancesmake it necessary to obtain samples from a stockpile of coarseaggregate or a stockpile of combined coarse and fine aggregate,design a sampling plan for the specific case under consider-ation to ensure that segregation does not introduce a bias in theresults. Th
34、is approach will allow the sampling agency to use asampling plan that will give a confidence in results obtainedtherefrom that is agreed upon by all parties concerned to beFIG. 1 Belt Sampling TemplateD75/D75M 142acceptable for the particular situation. The sampling plan shalldefine the number of sa
35、mples necessary to represent lots andsublots of specific sizes. The sampling plan shall also defineany specialized site-specific sampling techniques or proceduresthat are required to ensure unbiased samples for existingconditions. The owner and supplier shall agree upon the use ofany specialized sit
36、e-specific techniques or procedures. Whensite-specific techniques or procedures are developed for sam-pling a stockpile, those procedures shall supersede the proce-dures given in 5.3.3.1.(Note 6). General principles for sam-pling from stockpiles are applicable to sampling from trucks,rail cars, barg
37、es, or other transportation units.NOTE 6Specific site sampling plans may include the number ofsampling increments (loader buckets) required to construct the samplingpad.5.3.3.1 Sampling from Stockpiles with Power Equipment(preferred)In sampling material from stockpiles it is verydifficult to ensure
38、unbiased samples due to the segregationwhich often occurs when material is stockpiled, with coarserparticles rolling to the outside base of the pile. For coarse ormixed coarse and fine aggregate, every effort shall be made toenlist the services of power equipment to develop a separatesmall sampling
39、pile.(1) When obtaining a sample from a stockpile for accep-tance testing, a loader shall enter the stockpile nearest the arearepresenting material that is currently being shipped or loadedinto a production facility, with the bucket approximately 150mm 6 in. above ground level, never allowing the fr
40、ont tires ofthe loader to ramp up on the pile. Without backing up, theloader shall lift the full bucket of material then tilt the bucketdown to gently roll the material out of the bucket back onto thepile, thus re-blending any segregated material on the outsidesurface of the pile. If prior visual in
41、spection noted discerniblevariation, or if the loader is not of sufficient size to cause acascading effect down the face of the pile during this remixingprocess, several buckets of material shall either be remixed orremoved and discarded to prevent use of potentially injuriousmaterial.(2) After re-b
42、lending, the loader shall re-enter thestockpile, as before, and obtain a full loader bucket of there-blended material, tilt back and lift the bucket only highenough to back up slightly.(3) At the base of the main stockpile with the bucket onlyhigh enough to permit free-flow of the material from theb
43、ucket, the loader operator shall tilt the bucket forward togently roll the material out of the bucket forming a smallsampling pile. If the loader bucket is not of sufficient size tocreate a sample pad of representative size, multiple bucketsshall be used, dumped on top of each other and back-dragged
44、to form a single sample pad.(4) At this point the loader operator shall raise the bucket,drive forward far enough to reach across the small pile with theloader bucket without allowing the loader tires to ramp up onthe sampling pile, lower the bucket to about half the height ofthe small pile, and bac
45、kup, therefore creating a flat surface forsampling (see Fig. 3). The loader shall only back-drag thesmall pile once. This flat surface provides a stable and safe areato obtain a representative sample.(5) Place the sample bucket(s) near the center of the flat,oval-shaped sampling pad. The sample shal
46、l be obtained acrossthe entire flat area, but avoid sampling within 0.3 m 1 ft of thesample pad edge. Divide the sample pad into 4 quadrants andsample equal amounts of materials evenly across each quad-rant. Fully insert the shovel as near vertical as possible thengently roll the shovel back and lif
47、t slowly to avoid coarsematerial rolling off the sides of the shovel (Note 7). Obtainadditional shovelfuls from different quadrants of the samplingpad, and in areas that avoid previous “shovel holes.”NOTE 7Square-tip shovels with the outer edges rolled up approxi-mately 50 mm 2 in. on each side work
48、s well in preventing material fromrolling from the side. Spade-tip shovels are not recommended.5.3.3.2 Sampling from Stockpiles Without Power Equip-ment:NOTE 8Sampling coarse aggregate and coarse and fine mixedaggregate stockpiles without the aid of power equipment is not advised.(1) Where power equ
49、ipment is not available, samples fromstockpiles shall be made up of at least three increments takenfrom the top third, at the mid-point, and bottom third of theelevation of the stockpile.(2) Shove a board vertically into the pile just above thesampling point to prevent coarser material from rolling downand further segregating the material and biasing the sample.The board shall be of ample size to prevent material fromcascading down into the sampling area.(3) With the board in place, scrape off the outer mostsurface of the pile with the shovel, then inse
