1、Designation: D7759 12Standard Guide forNuclear Surface Moisture and Density Gauge Calibration1This standard is issued under the fixed designation D7759; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A n
2、umber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide describes the process and objective ofcalibrating the density system of a nuclear surface moisture anddensity gauge, or formu
3、lating the mathematical relationshipbetween the density system response (the “density count”) of anuclear surface moisture and density gauge and the corre-sponding density value of the density standard upon which thedensity system response was observed.1.2 This guide describes the process and object
4、ive ofcalibrating the water content system of a nuclear surfacemoisture and density gauge, or formulating the mathematicalrelationship between the water content system response (the“water content count”) of a nuclear surface moisture anddensity gauge and the corresponding water mass per unitvolume v
5、alue of the water content standard upon which thewater content system response was observed.1.3 This guide describes the process and objective ofverifying the density system of a nuclear surface moisture anddensity gauge.1.4 This guide describes the process and objective ofverifying the water conten
6、t system of a nuclear surfacemoisture and density gauge.1.5 This guide describes two mathematical processes bywhich the gauge measurement precision may be computed ormeasured.1.6 This guide offers guidance for developing and reportingestimates of uncertainties in measurements made with gaugesthat ha
7、ve undergone calibration or verification.1.7 All observed and calculated values shall confirm to theguide for significant digits and rounding established in PracticeD6026.1.8 This guide does not purport to address all of the safetyconcerns, if any, associated with its use. It is the responsibilityof
8、 the user of this guide to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.1.9 This guide offers an organized collection of informationor a series of options and does not recommend specific courseof action. This document cannot r
9、eplace education or experi-ence and should be used in conjunction with professionaljudgment. Not all aspects of this guide may be applicable in allcircumstances. This ASTM standard is not intended to repre-sent or replace the standard of care by which the adequacy ofa given professional service must
10、 be judged, nor should thisdocument be applied without consideration of a projects manyunique aspects. The word “Standard” in the title of thisdocument means only that the document has been approvedthrough the ASTM consensus process.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relatin
11、g to Soil, Rock, and ContainedFluidsD2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD6026 Practice for Using Significant Digits in GeotechnicalDataD6938 Test Method for In-Place Density and Water Contentof Soil and Soil-Aggregate by Nuclear Method
12、s (ShallowDepth)D7013 Guide for Nuclear Surface Moisture and DensityGauge Calibration Facility Setup3. Terminology3.1 DefinitionsSee Terminology D653 for general defini-tions.3.2 Definitions of Terms Specific to This Standard:3.2.1 coverage factor3, na number larger than one bywhich a combined stand
13、ard measurement uncertainty is mul-tiplied to obtain an expanded measurement uncertainty.3.2.2 definitional uncertainty3, nthe component of mea-surement uncertainty resulting from the finite amount of detailin the definition of the measurand. The “measurand” in the caseof a nuclear surface moisture
14、density gauge, is typically eitherin-place density or water mass per unit volume.3.2.3 density system calibration, nthe method by whichthe values of the fit parameters in the equation that relates the1This practice is under the jurisdiction of ASTM Committee D18 on Soil andRock and is the direct res
15、ponsibility of Subcommittee D18.08 on Special andConstruction Control Tests.Current edition approved Feb. 1, 2012. Published March 2012. DOI: 10.1520/D7759-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of
16、ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3JCGM 200:2008: International Vocabulary of MetrologyBasic and GeneralConcepts and Associated Terms (VIM). 2008: Joint Document Committee forGuides in Metrology.1Copyright ASTM International, 100 Barr H
17、arbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.density system response (the “density count”) of a nucleargauge and the corresponding density value of the densitystandard upon which that density system response was ob-served are computed. In addition, the uncertainty of mea
18、sure-ments taken with gauges calibrated by the specific methodmust be known at representative density values that span therange of densities for which the calibration is valid.3.2.4 density system verification, na set of operations orprocesses, or both, by which, for each density standard used inthe
19、 process, the in-place density value(s) measured by thenuclear gauge on the density standard is related to thecorresponding value(s) of the standard or standards. In addi-tion, the uncertainty of measurements taken with gauges thatmeets the established verification criterion or criteria must beknown
20、 at representative densities that span the range ofdensities for which the verification is valid.3.2.5 detector, na device to detect and measure radiation.3.2.6 expanded measurement uncertainty3, nproduct of acombined standard measurement uncertainty and a coveragefactor larger than one.3.2.7 gamma
21、(radiation) source, na sealed source ofradioactive material that emits gamma radiation as it decays.3.2.8 in-place density, nthe total mass (solids plus water)per total volume of soil or soil-aggregates measured in place.3.2.9 measurement uncertainty3, nnon-negative param-eter characterizing the dis
22、persion of the quantity values beingattributed to a measurand. The “measurand” in the case of anuclear surface moisture density gauge, is typically eitherin-place density or water mass per unit volume.3.2.10 neutron (radiation) source, na sealed source ofradioactive material that emits neutron radia
23、tion as it decays.3.2.11 nuclear gauge, na device containing one or moreradioactive sources used to measure certain properties of soiland soil-aggregates.3.2.12 prepared standards, ndensity or water contentmeasurement standards prepared of soil, solid rock, concrete,and engineered materials, that ha
24、ve density or water contentvalues, or both, that are established and known to a specifieduncertainty.3.2.13 source rod, na metal rod attached to a nucleargauge in which a radioactive source or a detector is housed.The rod can be lowered to specified depths for testing.3.2.14 standard measurement unc
25、ertainty3,nmeasurement uncertainty expressed as a standard devia-tion.3.2.15 test count, N, nthe measured output of a detectorfor a specific type of radiation for a given test.3.2.16 Type A Uncertainty Evaluation3, nevaluation of acomponent of measurement uncertainty by a statistical analysisof meas
26、ured quantity values obtained under defined measure-ment conditions.3.2.17 Type B Uncertainty Evaluation3, nevaluation of acomponent of measurement uncertainty by means other than aType A Evaluation.3.2.18 volumetric water content, nthe volume of water asa percent of the total volume of soil or rock
27、 material.3.2.19 water content, nthe ratio of the mass of watercontained in the pore spaces of soil or soil-aggregate, to thesolid mass of particles in that material, expressed as a percent-age (this is sometimes referred to in some scientific fields asgravimetric water content to differentiate it f
28、rom volumetricwater content).3.2.20 water content system calibration, nthe method bywhich the values of the fit parameters in the equation thatrelates the water content system response (the “water contentcount”) of a nuclear gauge and the corresponding water massper unit volume value of the water co
29、ntent standard uponwhich that water content system response was observed arecomputed. In addition, the uncertainty of measurements takenwith the gauges calibrated by the specific method must beknown at representative water mass per unit volume values thatspan the range of water mass per unit volume
30、values for whichthe calibration is valid.3.2.21 water content system verification, na set of opera-tions or processes, or both, by which, for each water contentstandard used in the process, the in-place water mass per unitvolume value(s) measured by the nuclear gauge on watercontent standard is rela
31、ted to the corresponding value(s) ofthese standards. In addition, the uncertainty of measurementstaken with gauges that meets the established verificationcriterion or criteria must be known at representative water massper unit volume values that span the range of water mass perunit volume values for
32、 which the verification is valid.3.2.22 water mass per unit volume, nthe ratio of the massof water contained in the pore spaces of a soil or soil-aggregateto the total volume occupied by that soil or rock material.4. Summary of Practice4.1 The objectives of the practice are as follows:4.1.1 The obje
33、ctive of density system calibration is toformulate a mathematical equation, or density calibrationequation, that relates the gauge density system response (the“density count”) to the soil-equivalent density of the standardon which this response is elicited. The maximum uncertaintiesof subsequent gau
34、ge density readings shall be determined forthe calibration process that is used. The standards used for thedetermination of uncertainty shall be representative of therange of densities for which the gauge will be used.4.1.2 The objective of density system verification is toevaluate the current densi
35、ty calibration equation for the gaugeand determine if a new calibration is required. The verificationmethod will be based upon relating, at the pertinent density ordensities for the specific method, the density value of a knowndensity standard to the density measured by the gauge. Themaximum uncerta
36、inties of subsequent gauge density readingsshall be determined for the verification method used. Thestandards used for the determination of uncertainty shall berepresentative of the range of densities for which the gauge willbe used.4.1.3 The objective of water content system calibration isto formul
37、ate a mathematical equation, or water content cali-bration equation, that relates the gauge water content systemresponse (the “water content count”) to the water mass per unitvolume value of the standard on which this response is elicited.The uncertainties of subsequent gauge water mass per unitvolu
38、me readings for low and high water mass per unit volumestandards used for the determination of uncertainty shall beD7759 122determined for the calibration process that is used. The low andhigh water mass per unit volume standards shall span the rangeof water mass per unit volume values for which the
39、 gauge willbe used.4.1.4 The objective of water content system verification isto evaluate the current water content system calibration equa-tion for the gauge and determine if a new calibration isrequired. This evaluation will be based upon relating, at thepertinent water mass per unit volume values
40、 for the specificmethod, the water mass per unit volume value of a knownwater mass per unit volume standard to the water mass per unitvolume value measured by the gauge. The uncertainties ofsubsequent gauge water mass per unit volume readings for lowand high water mass per unit volume standards used
41、 for thedetermination of uncertainty shall be determined for thecalibration process that is used. The low and high water massper unit volume standards shall span the range of water massper unit volume values for which the gauge will be used.4.1.5 The density calibration equation relates the in-place
42、density value measured by the gauge on a test site (the“independent variable”) with the density test count measuredby the gauge on the test site (the “dependent variable”) istypically exponential or polynomial in form, with three fitcoefficients.4.2 Historically, the most successful methods for cali
43、bratingthe density system of a gauge is done by taking gauge densityreadings on three or more density standards, combining theindependent and dependent variables into data pairs, and usinga least-squares or Newton-Rafson fitting algorithm with thesedata pairs to compute the fit coefficients. These d
44、ensitystandards have unique density values that span the range ofdensities for which the gauge will be used.4.2.1 The density system calibration of a gauge is notnecessarily limited to the process described in 4.2. However,for any method that is used in the density system calibrationprocess, one mus
45、t know the uncertainties of the in-placedensity readings measured by devices calibrated in this mannerover the range of density values for which the gauge will beused.4.2.2 For any method that is used in the density systemverification process, one must know the uncertainties of thein-place density r
46、eadings measured by devices calibrated inthis manner over the range of density values for which thegauge will be used.4.2.3 The water content calibration equation that relates thein-place water mass per unit volume value measured by thegauge on a test site (the “independent variable”) with the water
47、content test count measured by the gauge on the test site (the“dependent variable”) is typically linear in form, with two fitcoefficients.4.3 Historically, the most successful method for calibratingthe water content system of a gauge is by taking readings ontwo water content standards (one of which
48、is a zero watercontent standard), combining the independent and dependentvariables into data pairs, and using a least-squares or fittingalgorithm with these data pairs to compute the fit coefficients.4.3.1 The water content system calibration of a gauge is notnecessarily limited to the process descr
49、ibed in 4.3. However,for any method that is used in the water content systemcalibration process, one must know the uncertainties of thewater mass per unit volume readings measured by devicescalibrated in this manner over the range of mass per unitvolume values for which the gauge will be used.4.3.2 For any method that is used in the water contentsystem verification process, one must know the uncertainties ofthe water mass per unit volume readings measured by devicescalibrated in this manner over the range of mass per unitvolume values for which the gauge will
