ASTM C1040/C1040M-08(2013)
(Test Method)Standard Test Methods for In-Place Density of Unhardened and Hardened Concrete, Including Roller Compacted Concrete, By Nuclear Methods
Standard Test Methods for In-Place Density of Unhardened and Hardened Concrete, Including Roller Compacted Concrete, By Nuclear Methods
SIGNIFICANCE AND USE
3.1 These test methods are useful as rapid, nondestructive techniques for the in-place determination of the density of unhardened concrete. The backscatter test method is also useful for the same purpose on hardened concrete. The fundamental assumptions inherent in the test methods are that Compton scattering is the dominant interaction and that the material under test is homogeneous.
3.2 These test methods are suitable for control and for assisting in acceptance testing during construction, for evaluation of concrete quality subsequent to construction, and for research and development. Note 1—Care must be taken when using these test methods in monitoring the degree of consolidation, which is the ratio of the actual density achieved to the maximum density attainable with a particular concrete. The test methods presented here are used to determine the actual density. A density measurement, by any test method, is a function of the components of the concrete and may vary, to some extent, in response to the normal, acceptable variability of those components.
3.3 Test results may be affected by reinforcing steel, by the chemical composition of concrete constituents, and by sample heterogeneity. The variations resulting from these influences are minimized by instrument design and by the user's compliance with appropriate sections of the test procedure. Results of tests by the backscatter test method may also be affected by the density of underlying material. The backscatter test method exhibits spatial bias in that the apparatus's sensitivity to the material under it decreases with distance from the surface of the concrete.Note 2—Typically, backscatter gauge readings represent the density in the top 75 to 100 mm [3 to 4 in.] of material.
SCOPE
1.1 These test methods cover the determination of the in-place density of unhardened and hardened concrete, including roller compacted concrete, by gamma radiation. For notes on the nuclear test see Appendix X1.
1.2 Two test methods are described, as follows:
Section
Test Method A—Direct Transmission
Test Method B—Backscatter
7
8
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation: C1040/C1040M − 08(Reapproved 2013)
Standard Test Methods for
In-Place Density of Unhardened and Hardened Concrete,
Including Roller Compacted Concrete, By Nuclear Methods
This standard is issued under the fixed designation C1040/C1040M; the number immediately following the designation indicates the
year of original adoption 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. Scope* unhardened concrete. The backscatter test method is also
useful for the same purpose on hardened concrete. The
1.1 These test methods cover the determination of the
fundamental assumptions inherent in the test methods are that
in-place density of unhardened and hardened concrete, includ-
Compton scattering is the dominant interaction and that the
ing roller compacted concrete, by gamma radiation. For notes
material under test is homogeneous.
on the nuclear test see Appendix X1.
3.2 These test methods are suitable for control and for
1.2 Two test methods are described, as follows:
assisting in acceptance testing during construction, for evalu-
Section
ation of concrete quality subsequent to construction, and for
Test MethodA—Direct Transmission 7
research and development.
Test Method B—Backscatter 8
NOTE 1—Care must be taken when using these test methods in
1.3 The values stated in either SI units or inch-pound units
monitoring the degree of consolidation, which is the ratio of the actual
are to be regarded separately as standard. The values stated in
density achieved to the maximum density attainable with a particular
each system may not be exact equivalents; therefore, each
concrete.The test methods presented here are used to determine the actual
system shall be used independently of the other. Combining density. A density measurement, by any test method, is a function of the
components of the concrete and may vary, to some extent, in response to
values from the two systems may result in non-conformance
the normal, acceptable variability of those components.
with the standard.
3.3 Test results may be affected by reinforcing steel, by the
1.4 This standard does not purport to address all of the
chemical composition of concrete constituents, and by sample
safety concerns, if any, associated with its use. It is the
heterogeneity. The variations resulting from these influences
responsibility of the user of this standard to establish appro-
are minimized by instrument design and by the user’s compli-
priate safety and health practices and determine the applica-
ance with appropriate sections of the test procedure. Results of
bility of regulatory limitations prior to use.
tests by the backscatter test method may also be affected by the
2. Referenced Documents
density of underlying material. The backscatter test method
exhibits spatial bias in that the apparatus’s sensitivity to the
2.1 ASTM Standards:
material under it decreases with distance from the surface of
C29/C29M Test Method for Bulk Density (“Unit Weight”)
the concrete.
and Voids in Aggregate
NOTE 2—Typically, backscatter gauge readings represent the density in
C138/C138M Test Method for Density (Unit Weight),Yield,
the top 75 to 100 mm [3 to 4 in.] of material.
and Air Content (Gravimetric) of Concrete
C670 Practice for Preparing Precision and Bias Statements
4. Apparatus
for Test Methods for Construction Materials
4.1 The exact details of construction of the apparatus may
3. Significance and Use
vary,buttheapparatusasawholeshallsatisfytherequirements
3.1 These test methods are useful as rapid, nondestructive for system precision stated in Annex A1. The system shall
techniques for the in-place determination of the density of
consist of the following:
4.1.1 Gamma Source—An encapsulated and sealed radio-
These test methods are under the jurisdiction of ASTM Committee C09 on
isotopic source, such as cesium-137 (see X1.2).
Concrete and ConcreteAggregatesand are the direct responsibility of Subcommittee
4.1.2 Detector—Any type of gamma detector, such as a
C09.45 on Roller-Compacted Concrete.
Geiger-Müller tube, scintillation crystal, or proportional coun-
Current edition approved Nov. 15, 2013. Published December 2013. Originally
ter.
approved in 1985. Last previous edition approved in 2008 as C1040 – 08. DOI:
10.1520/C1040_C1040M-08R13.
4.1.3 Probe—For direct transmission measurements, either
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
thegammasourceorthedetectorshallbehousedinaprobefor
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
inserting in a preformed hole in the material to be tested. The
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. probe shall be marked in increments of 50 mm [2 in.] for tests
*A Summary of Changes section appears at the end of this standard
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959. United States
C1040/C1040M − 08 (2013)
with probe depths from 50 to 300 mm [2 to 12 in.]. The probe differs significantly from that for which the calibration curve
shall be so made mechanically, that when moved manually to was established. An adjustment is also necessary if the testing
the marked depth desired, it will be held securely in position at equipment has been changed. Adjustment is particularly im-
that depth. portant for backscatter test method measurements. Determine
the necessary adjustments using the same mode of operation
4.1.4 Readout Instrument—A suitable scaler or direct read-
out meter. and at the same depth (if using direct transmission) as that
intendedfortesting.Arecommendedprocedureformakingthis
4.1.5 Gauge Housing—The source, detector, readout instru-
ment and appropriate power supplies shall be in housings of adjustment is as follows:
rugged construction that are moisture and dust proof. 5.2.1 Prepare a concrete mix similar in composition to the
4.1.6 Reference Standard—Ablock of uniform, unchanging material to be tested subsequently.
density provided for checking equipment operation, back-
5.2.2 Fill the calibration adjustment container with concrete
ground count, and count-rate reproducibility.
and consolidate to produce a uniform, homogeneous material
4.1.7 Guide Plate and Hole-Forming-Device—For direct with approximately the density that will be achieved in the
transmission measurements, a guide plate and a device, such as
construction.
apinordrillrod,havinganominaldiameterslightlylargerthan
NOTE 5—Consolidation may be achieved by the procedure used for unit
theprobe,forformingaholenormaltotheconcretesurfaceare
weight testing (Test Method C138/C138M) or by other methods, such as
required.
spading the concrete and then dropping the ends of the container
4.1.8 Calibration Adjustment Container—The container alternately on a rigid surface.
shall be rigid and watertight, with minimum inside dimensions
5.2.3 Strike off the container with strike-off plate or bar.
large enough to allow the calibration curve adjustment proce-
Take care to make the concrete surface flat and flush with the
dure (5.2) to be followed with no effect of the finite size of the
container edges.
container on the instrument’s responses. The volume of the
NOTE 6—A2 mm [ ⁄16 in.] average difference between the concrete
container shall be established following the procedure outlined
surface and the container edges in a 150 mm [6 in.] deep container will
in Test Method C29/C29M.
producea1to2% error in the weighed density of the concrete.
NOTE 3—For backscatter measurements, a container 450 by 450 by 150
5.2.4 Weigh the concrete in the container to the nearest 0.2
mm [18 by 18 by 6 in.] will meet this requirement for most equipment
kg [0.5 lb] and determine the weighed density as follows:
currently available commercially. For 50-mm [2-in.] depth direct trans-
mission measurements, a container 600 by 600 by 100 mm [24 by 24 by
W
c
4 in.] will meet this requirement.
W 5 (1)
V
4.1.9 Scale—The scale shall be accurate to within 0.2 kg
where:
[0.5lb]ofthetestloadatanypointwithintherangeofuse.The
3 3
W = weighed density of concrete, kg/m [lb/ft ],
range of use shall be considered to extend from the weight of
W = mass of the concrete, kg [lb], and
c
thecalibrationadjustmentcontainerempty,totheweightofthe
3 3
3 3 V = volume of the container, m [ft ].
measure plus the contents at 2600 kg/m [160 lb/ft ].
4.1.10 Strike-Off Plate or Bar—This shall be a flat metal or
5.2.5 Immediately take three automatically timed direct
glass plate or metal bar with a length at least 50 mm [2 in.]
transmission or backscatter readings with the instrument cen-
greater than the length, width, or diameter of the calibration
tered on the surface of the concrete in the container. Rotate the
adjustment container.The strike-off must be rigid, straight, and
base of the instrument 90° around the vertical axis, with
smoothenoughtofinishtheconcretesurfaceflatandflushwith
subsequent rotations of 180 and 270° from the original
the edges of the calibration adjustment container.
position. Obtain three additional automatically timed counts at
each position. The instrument must be centered over the
5. Calibration
surface of the concrete in each rotated position to prevent edge
effects on the instrument reading.
5.1 Calibration curves are established by determining the
5.2.6 Using the applicable calibration curve, determine the
nuclear count rate of each of several materials at different and
density from the average of the 12 counts obtained in 5.2.5.
known densities, plotting the count rate (or count ratio) versus
5.2.7 Determine the difference between the two density
each known density, and placing a curve through the resulting
readings obtained in 5.2.4 and 5.2.6.
points. The method used to establish the curve must be the
same as that used to determine the density. The materials used 5.2.8 Repeat 5.2.2 – 5.2.7 on two additional concrete mixes
for calibration must be of uniform density. of the same proportions. Determine the adjustment factor by
averaging the three values obtained in5.2.7 and 5.2.8. If one of
NOTE 4—Calibration curves are supplied by gauge manufacturers, or
the three values differs from the average by more than 25
can be established using blocks of known density or prepared containers
3 3
kg/m [1.5 lb/ft ], discard it as a statistical outlier and recalcu-
of uniform, unchanging material compacted to known densities. Materials
consideredsatisfactoryforuseinblocksincludegranite,aluminum,chalk, late the adjustment factor as the average of the remaining two
limestone, and magnesium.
values.
5.2 Adjusting Calibration Curves—Prior to use, adjust the 5.2.9 Use the adjustment factor determined in 5.2.8 to plot
instrument’s calibration curve, if necessary, to compensate for a corrected count-rate calibration curve which shall be parallel
chemical composition effects. Such an adjustment is necessary to the original calibration curve and offset by the amount
wheneverthechemicalcompositionoftheconcretetobetested indicated in 5.2.8. Alternatively, the value of the adjustment
C1040/C1040M − 08 (2013)
factor shall be attached to the instrument and applied to all 7.1.2 Reinforcing steel shall not be present in the volume
density determinations arrived at from an original (unadjusted) bounded by the extended probe and the detector tubes.
calibration curve. 7.1.3 The test location shall contain concrete to a depth 25
mm[1in.]greaterthanthattowhichtheprobewillbeinserted.
NOTE 7—In some circumstances, for example, where chemical compo-
In thin concrete overlay projects, this may require the removal
sition changes are minimal, calibration curve adjustments may be estab-
of the underlying (original) concrete 25 to 50 mm [1 to 2 in.]
lished on permanent, uniform, hardened concrete blocks.
down over a small area before placement of the overlay.
6. Standardization
7.2 Smooth the surface with a wood float. If necessary, use
6.1 Standardization of the equipment on the reference stan-
the guide plate and hole-forming device (4.1.7) to make a hole
dard is required at the start of each day and whenever test
slightly larger than the probe and perpendicular to the surface.
measurements are suspect.
In some concretes, the probe may be inserted directly into the
concrete without the use of the guide plate and hole-forming
NOTE 8—In some older instrument models, count rates are strongly
influenced by the ambient temperature; frequent standardization may be device.
necessary.
7.3 Insert the probe so that the side of the probe facing the
6.2 Warm-up time shall be in accordance with the manufac-
center of the gauge is in intimate contact with the side of the
turer’s recommendations.
hole. Keep all other radioactive sources at such a distance from
the gauge that the readings will not be affected.
6.3 Take at least five readings on the reference standard,
more if recommended by the manufacturer, or take one 4 min
NOTE 9—The recommended minimum distance from other nuclear
or longer count if the instrument is equipped with automatic
density gauges is 10 m [30 ft].
standard count storage.
7.4 Use the same warm-up time as in standardization. Take
6.4 Ifmorethanoneoftheindividualreadingsisoutsidethe
automatically timed readings, for a minimum of 1 min, and
limit set by Eq 2, repeat the standardization. If the second
determine the in-place density from the adjusted calibration
attempt does not satisfy Eq 2, check the system for a malfunc-
curve. Alternatively, determine the in-place density from the
tion. If no malfunction is found, establish a new N (average
unadjusted calibration curve and then apply the calibration
o
count) by taking the average of a minimum of 10 counts on the
adjustment factor (5.2.9). If the instrument has a direct reading
reference standard.
display which is not programmed to apply the calibration
adjustment factor (5.2.8), correct the displayed density by
=
N 2 N ,1.96 N (2)
? s o? o
applying that factor.
where:
TEST METHOD B—BACKSCATTER (FOR
N = count currently measured in checking the instrument
s
UNHARDENED OR HARDENED CONCRETE)
operation, and
N = average count previously established on the reference
8. Procedure
o
standard.
8.1 Selectatestlocationsuchthat,whenthegaugeisplaced
In instruments where the count has been prescaled, that is,
in test position:
divided by a constant factor k before it is displayed, Eq 2 shall
8.1.1 Any point on the source-detector axis shall be at least
be replaced by the following:
230 mm [9 in.] from any pavement edge or object, and
8.1.2 No reinforcing steel with less than 75 mm [3 in.] of
N 2 N ,1
...
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