1、Designation: C 1040 05Standard 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; the number immediately following the designation indicates the year oforiginal adopt
2、ion or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the determination of thein-place density of unh
3、ardened 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 inch-pound units are to be re
4、gardedas the standard. The SI equivalents of inch-pound units may beapproximate.1.4 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 det
5、ermine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards: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 f
6、or Preparing Precision and Bias Statementsfor Test Methods for Construction Materials3. Significance and 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
7、 purpose on hardened concrete. Thefundamental assumptions inherent in the test methods are thatCompton scattering 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
8、 evalu-ation of concrete quality subsequent to construction, and forresearch and development.NOTE 1Care must 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.
9、The test methods presented here are used to determine the actualdensity. A density measurement, by any test 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 re
10、inforcing steel, by thechemical composition of concrete constituents, and by sampleheterogeneity. The variations 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 met
11、hod may also be affected by thedensity of underlying material. The backscatter test methodexhibits spatial bias in that the apparatuss sensitivity to thematerial under it decreases with distance from the surface ofthe concrete.4. Apparatus4.1 The exact details of construction of the apparatus mayvar
12、y, 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).4.1.2 DetectorAny type of gamma detector, such as aGeiger-
13、Mller tube, scintillation crystal, or proportionalcounter.4.1.3 ProbeFor direct transmission measurements, eitherthe gamma source or the detector shall be housed in a probe forinserting in a preformed hole in the material to be tested. Theprobe shall be marked in increments of 2 in. (50 mm) for test
14、s1These test methods are under the jurisdiction of ASTM Committee C09 onConcrete and ConcreteAggregates and are the direct responsibility of SubcommitteeC09.45 on Roller-Compacted Concrete.Current edition approved July 1, 2005. Published August 2005. Originallyapproved in 1985. Last previous edition
15、 approved in 2000 as C 1040 00.2For 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.1Copyright ASTM International,
16、 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.with probe depths from 2 to 12 in. (50 to 300 mm). The probeshall be so made mechanically, that when moved manually tothe marked depth desired, it will be held securely in position atthat depth.4.1.4 Readout Instrum
17、entA suitable scaler or direct read-out meter.4.1.5 Gage 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 StandardA block of uniform, unchangingdensity provided for checking equ
18、ipment 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 slightly larger thanthe probe, for forming a hole normal to the concrete
19、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 effect of the finite size of thecontainer on the instruments responses.
20、The volume of thecontainer shall be established following the procedure outlinedin Test Method C 29/C 29M.NOTE 2For backscatter measurements, a container 18 by 18 by 6 in.(450 by 450 by 150 mm) will meet this requirement for most equipmentcurrently available commercially. For 2-in. (50-mm) depth dir
21、ect trans-mission measurements, a container 24 by 24 by 4 in. (600 by 600 by 100mm) will meet this requirement.4.1.9 ScaleThe scale shall be accurate to within 0.5 lb(0.2 kg) of the test load at any point within the range of use.The range of use shall be considered to extend from the weightof the ca
22、libration adjustment container empty, to the weight ofthe measure plus the contents at 160 lb/ft3(2600 kg/m3).4.1.10 Strike-Off Plate or BarThis shall be a flat metal orglass plate or metal bar with a length at least 2 in. (50 mm)greater than the length, width, or diameter of the calibrationadjustme
23、nt 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 thenuclear count rate of each of several materials at differe
24、nt 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 materials usedfor calibration must be of uniform density.NOTE 3
25、Calibration curves are supplied by gage manufacturers, or canbe established using blocks of known density or prepared containers ofuniform, unchanging material compacted to known densities. Materialsconsidered satisfactory for use in blocks include granite, aluminum, chalk,limestone, and magnesium.5
26、.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 testeddiffers significantly from that for which the calibration cu
27、rvewas 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 operationand at the same depth (if using direct transmission) as tha
28、tintended 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 concreteand consolidate to produce a uniform, homogeneous materialwit
29、h approximately the density that will be achieved in theconstruction.NOTE 4Consolidation 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 dropping the ends of the containeralternately on a rigid surface.
30、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 5A116 in. (1.6 mm) average difference between the concretesurface and the container edges in a 6 in. (150 mm) deep container willproduce a 1.0 % error in the
31、 weighed density of the concrete.5.2.4 Weigh the concrete in the container to the nearest 0.5lb (250 g) and determine the weighed density as follows:W 5WcV(1)where:W = weighed density of concrete, lb/ft3(kg/m3),Wc= weight of the concrete, lb (kg), andV = volume of the container, ft3(m3).5.2.5 Immedi
32、ately 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 from the originalposition. Obtain three
33、 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 from the average of the 12 counts obtai
34、ned 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 5.2.7 and 5.2.8. If one ofthe three value
35、s differs from the average by more than 1.5 lb/ft3(24 kg/m3), discard it as a statistical outlier and recalculate theadjustment factor as the average of the remaining two values.5.2.9 Use the adjustment factor determined in 5.2.8 to plota corrected count-rate calibration curve which shall be paralle
36、lto the original calibration curve and offset by the amountindicated in 5.2.8. Alternatively, the value of the adjustmentC1040052factor shall be attached to the instrument and applied to alldensity determinations arrived at from an original (unadjusted)calibration curve.NOTE 6In some circumstances,
37、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 required at the start of each day and whenever testmeas
38、urements are suspect.NOTE 7In 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 at least five readings on the reference standar
39、d,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. If the secondattempt does not satisfy Eq 2, chec
40、k 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 instrumentoperation, andNo= average count previously establi
41、shed 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 used and thenewly established count is outside
42、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 more than 10 % from the standardcount at which
43、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 gage is placedin test position:7.1.1 Any point on the source-detector axis shall be at least9 in. (230 mm) from a
44、ny 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 1 in.(25 mm) greater than that to which the probe will be inserted.In thin concrete overlay projects, th
45、is may require the removalof the underlying (original) concrete 1 to 2 in. (25 to 50 mm)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 a holeslightly larger than the probe and p
46、erpendicular 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 gage is in intimate contact with the side of thehole. Keep all other
47、 radioactive sources at such a distance fromthe gage that the readings will not be affected.NOTE 8Thirty feet (10 m) is the recommended minimum distancefrom other nuclear density gages.7.4 Use the same warm-up time as in standardization. Takeautomatically timed readings, for a minimum of 1 min, andd
48、etermine 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 calibration
49、adjustment factor (5.2.8), correct the displayed density byapplying that factor.TEST METHOD BBACKSCATTER (FORUNHARDENED OR HARDENED CONCRETE)8. Procedure8.1 Select a test location such that, when the gage is placedin test position:8.1.1 Any point on the source-detector axis shall be at least9 in. (230 mm) from any pavement edge or object, and8.1.2 No reinforcing steel with less than 3 in. (75 mm) ofconcrete cover shall lie directly under the source - detectoraxis, except as indicated in Note 9.NOTE 9The user may find that certain instrument models and
