1、Designation: C 1040/C 1040M 08Standard Test Methods forIn-Place Density of Unhardened and Hardened Concrete,Including Roller Compacted Concrete, By Nuclear Methods1This standard is issued under the fixed designation C 1040/C 1040M; the number immediately following the designation indicates theyear o
2、f original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods cover the determination of thein-plac
3、e density of unhardened and hardened concrete, includ-ing roller compacted concrete, by gamma radiation. For noteson the nuclear test see Appendix X1.1.2 Two test methods are described, as follows:SectionTest Method ADirect TransmissionTest Method BBackscatter781.3 The values stated in either SI uni
4、ts 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 no
5、t 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. Referenced Documents2.1 ASTM Standard
6、s:2C 29/C 29M Test Method for Bulk Density (“Unit Weight”)and Voids in AggregateC 138/C 138M Test Method for Density (Unit Weight),Yield, and Air Content (Gravimetric) of ConcreteC 670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction Materials3. Significance and
7、Use3.1 These test methods are useful as rapid, nondestructivetechniques for the in-place determination of the density ofunhardened concrete. The backscatter test method is alsouseful for the same purpose on hardened concrete. Thefundamental assumptions inherent in the test methods are thatCompton sc
8、attering is the dominant interaction and that thematerial under test is homogeneous.3.2 These test methods are suitable for control and forassisting in acceptance testing during construction, for evalu-ation of concrete quality subsequent to construction, and forresearch and development.NOTE 1Care m
9、ust be taken when using these test methods inmonitoring the degree of consolidation, which is the ratio of the actualdensity achieved to the maximum density attainable with a particularconcrete. The test methods presented here are used to determine the actualdensity. A density measurement, by any te
10、st method, is a function of thecomponents of the concrete and may vary, to some extent, in response tothe normal, acceptable variability of those components.3.3 Test results may be affected by reinforcing steel, by thechemical composition of concrete constituents, and by sampleheterogeneity. The var
11、iations resulting from these influencesare minimized by instrument design and by the users compli-ance with appropriate sections of the test procedure. Results oftests by the backscatter test method may also be affected by thedensity of underlying material. The backscatter test methodexhibits spatia
12、l bias in that the apparatuss sensitivity to thematerial under it decreases with distance from the surface ofthe concrete.NOTE 2Typically, backscatter gauge readings represent the density inthe top 75 to 100 mm 3 to 4 in. of material.4. Apparatus4.1 The exact details of construction of the apparatus
13、 mayvary, but the apparatus as a whole shall satisfy the requirementsfor system precision stated in Annex A1. The system shallconsist of the following:4.1.1 Gamma SourceAn encapsulated and sealed radio-isotopic source, such as cesium-137 (see X1.2).1These test methods are under the jurisdiction of A
14、STM Committee C09 onConcrete and ConcreteAggregates and are the direct responsibility of SubcommitteeC09.45 on Roller-Compacted Concrete.Current edition approved Oct. 1, 2008. Published November 2008. Originallyapproved in 1985. Last previous edition approved in 2005 as C 1040 05.2For referenced AST
15、M 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.1*A Summary of Changes section appears at the end of this standard.Copyright AST
16、M International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.1.2 DetectorAny type of gamma detector, such as aGeiger-Mller tube, scintillation crystal, or proportionalcounter.4.1.3 ProbeFor direct transmission measurements, eitherthe gamma source or the dete
17、ctor shall be housed in a probe forinserting in a preformed hole in the material to be tested. Theprobe shall be marked in increments of 50 mm 2 in. for testswith probe depths from 50 to 300 mm 2 to 12 in. The probeshall be so made mechanically, that when moved manually tothe marked depth desired, i
18、t will be held securely in position atthat depth.4.1.4 Readout InstrumentA suitable scaler or direct read-out meter.4.1.5 Gauge HousingThe source, detector, readout instru-ment and appropriate power supplies shall be in housings ofrugged construction that are moisture and dust proof.4.1.6 Reference
19、StandardA block of uniform, unchangingdensity provided for checking equipment operation, back-ground count, and count-rate reproducibility.4.1.7 Guide Plate and Hole-Forming-DeviceFor directtransmission measurements, a guide plate and a device, such asa pin or drill rod, having a nominal diameter sl
20、ightly larger thanthe probe, for forming a hole normal to the concrete surface arerequired.4.1.8 Calibration Adjustment Container The containershall be rigid and watertight, with minimum inside dimensionslarge enough to allow the calibration curve adjustment proce-dure (5.2) to be followed with no e
21、ffect of the finite size of thecontainer on the instruments responses. The volume of thecontainer shall be established following the procedure outlinedin Test Method C 29/C 29M.NOTE 3For backscatter measurements, a container 450 by 450 by 150mm 18 by 18 by 6 in. will meet this requirement for most e
22、quipmentcurrently available commercially. For 50-mm 2-in. depth direct trans-mission measurements, a container 600 by 600 by 100 mm 24 by 24 by4 in. will meet this requirement.4.1.9 ScaleThe scale shall be accurate to within 0.2 kg0.5 lb of the test load at any point within the range of use. Therang
23、e of use shall be considered to extend from the weight ofthe calibration adjustment container empty, to the weight of themeasure plus the contents at 2600 kg/m3160 lb/ft3.4.1.10 Strike-Off Plate or BarThis shall be a flat metal orglass plate or metal bar with a length at least 50 mm 2 in.greater tha
24、n the length, width, or diameter of the calibrationadjustment container. The strike-off must be rigid, straight, andsmooth enough to finish the concrete surface flat and flush withthe edges of the calibration adjustment container.5. Calibration5.1 Calibration curves are established by determining th
25、enuclear count rate of each of several materials at different andknown densities, plotting the count rate (or count ratio) versuseach known density, and placing a curve through the resultingpoints. The method used to establish the curve must be thesame as that used to determine the density. The mate
26、rials usedfor calibration must be of uniform density.NOTE 4Calibration curves are supplied by gauge manufacturers, orcan be established using blocks of known density or prepared containersof uniform, unchanging material compacted to known densities. Materialsconsidered satisfactory for use in blocks
27、 include granite, aluminum, chalk,limestone, and magnesium.5.2 Adjusting Calibration CurvesPrior to use, adjust theinstruments calibration curve, if necessary, to compensate forchemical composition effects. Such an adjustment is necessarywhenever the chemical composition of the concrete to be tested
28、differs significantly from that for which the calibration curvewas established. An adjustment is also necessary if the testingequipment has been changed. Adjustment is particularly im-portant for backscatter test method measurements. Determinethe necessary adjustments using the same mode of operatio
29、nand at the same depth (if using direct transmission) as thatintended for testing.Arecommended procedure for making thisadjustment is as follows:5.2.1 Prepare a concrete mix similar in composition to thematerial to be tested subsequently.5.2.2 Fill the calibration adjustment container with concretea
30、nd consolidate to produce a uniform, homogeneous materialwith approximately the density that will be achieved in theconstruction.NOTE 5Consolidation may be achieved by the procedure used for unitweight testing (Test Method C 138/C 138M) or by other methods, such asspading the concrete and then dropp
31、ing the ends of the containeralternately on a rigid surface.5.2.3 Strike off the container with strike-off plate or bar.Take care to make the concrete surface flat and flush with thecontainer edges.NOTE 6A2mm116 in. average difference between the concretesurface and the container edges in a 150 mm 6
32、 in. deep container willproducea1to2%error in the weighed density of the concrete.5.2.4 Weigh the concrete in the container to the nearest 0.2kg 0.5 lb and determine the weighed density as follows:W 5WcV(1)where:W = weighed density of concrete, kg/m3lb/ft3,Wc= mass of the concrete, kg lb, andV = vol
33、ume of the container, m3ft3.5.2.5 Immediately take three automatically timed directtransmission or backscatter readings with the instrument cen-tered on the surface of the concrete in the container. Rotate thebase of the instrument 90 around the vertical axis, withsubsequent rotations of 180 and 270
34、 from the originalposition. Obtain three additional automatically timed counts ateach position. The instrument must be centered over thesurface of the concrete in each rotated position to prevent edgeeffects on the instrument reading.5.2.6 Using the applicable calibration curve, determine thedensity
35、 from the average of the 12 counts obtained in 5.2.5.5.2.7 Determine the difference between the two densityreadings obtained in 5.2.4 and 5.2.6.5.2.8 Repeat 5.2.2-5.2.7 on two additional concrete mixesof the same proportions. Determine the adjustment factor byaveraging the three values obtained in 5
36、.2.7 and 5.2.8. If one ofthe three values differs from the average by more than 25C 1040/C 1040M 082kg/m31.5 lb/ft3, discard it as a statistical outlier and recalcu-late the adjustment factor as the average of the remaining twovalues.5.2.9 Use the adjustment factor determined in 5.2.8 to plota corre
37、cted count-rate calibration curve which shall be parallelto the original calibration curve and offset by the amountindicated in 5.2.8. Alternatively, the value of the adjustmentfactor shall be attached to the instrument and applied to alldensity determinations arrived at from an original (unadjusted
38、)calibration curve.NOTE 7In some circumstances, for example, where chemical compo-sition changes are minimal, calibration curve adjustments may be estab-lished on permanent, uniform, hardened concrete blocks.6. Standardization6.1 Standardization of the equipment on the reference stan-dard is require
39、d at the start of each day and whenever testmeasurements are suspect.NOTE 8In some older instrument models, count rates are stronglyinfluenced by the ambient temperature; frequent standardization may benecessary.6.2 Warm-up time shall be in accordance with the manufac-turers recommendations.6.3 Take
40、 at least five readings on the reference standard,more if recommended by the manufacturer, or take one 4 minor longer count if the instrument is equipped with automaticstandard count storage.6.4 If more than one of the individual readings is outside thelimit set by Eq 2, repeat the standardization.
41、If the secondattempt does not satisfy Eq 2, check the system for a malfunc-tion. If no malfunction is found, establish a new No(averagecount) by taking the average of a minimum of 10 counts on thereference standard.|Ns2 No| , 1.96 =No(2)where:Ns= count currently measured in checking the instrumentop
42、eration, andNo= average count previously established on the referencestandard.In instruments where the count has been prescaled, that is,divided by a constant factor k before it is displayed, Eq 2 shallbe replaced by the following:|Ns2 No| , 1.96 =No/k (3)6.4.1 If automatic standard count storage is
43、 used and thenewly established count is outside the limit set by Eq 2, repeatthe standardization.6.4.2 If the second attempt does not satisfy Eq 2, check thesystem for a malfunction.6.4.3 If no malfunction is found, establish a new Noequal tothe average count found in 6.4.2.6.5 If a new Nodiffers by
44、 more than 10 % from the standardcount at which the calibration curve (5.1) was established,recalibrate the instrument.TEST METHOD ADIRECT TRANSMISSION (FORUNHARDENED CONCRETE)7. Procedure7.1 Select a test location such that, when the gauge is placedin test position:7.1.1 Any point on the source-det
45、ector axis shall be at least230 mm 9 in. from any pavement edge or object.7.1.2 Reinforcing steel shall not be present in the volumebounded by the extended probe and the detector tubes.7.1.3 The test location shall contain concrete to a depth 25mm 1 in. greater than that to which the probe will be i
46、nserted.In thin concrete overlay projects, this may require the removalof the underlying (original) concrete 25 to 50 mm 1 to 2 in.down over a small area before placement of the overlay.7.2 Smooth the surface with a wood float. If necessary, usethe guide plate and hole-forming device (4.1.7) to make
47、 a holeslightly larger than the probe and perpendicular to the surface.In some concretes, the probe may be inserted directly into theconcrete without the use of the guide plate and hole-formingdevice.7.3 Insert the probe so that the side of the probe facing thecenter of the gauge is in intimate cont
48、act with the side of thehole. Keep all other radioactive sources at such a distance fromthe gauge that the readings will not be affected.NOTE 9The recommended minimum distance from other nucleardensity gauges is 10 m 30 ft.7.4 Use the same warm-up time as in standardization. Takeautomatically timed
49、readings, for a minimum of 1 min, anddetermine the in-place density from the adjusted calibrationcurve. Alternatively, determine the in-place density from theunadjusted calibration curve and then apply the calibrationadjustment factor (5.2.9). If the instrument has a direct readingdisplay which is not programmed to apply the calibrationadjustment factor (5.2.8), correct the displayed density byapplying that factor.TEST METHOD BBACKSCATTER (FORUNHARDENED OR HARDENED CONCRETE)8. Procedure8.1 Select a test locati
