ASTM C1040-93(2000)
(Test Method)Standard Test Methods for Density of Unhardened and Hardened Concrete In Place By Nuclear Methods
Standard Test Methods for Density of Unhardened and Hardened Concrete In Place By Nuclear Methods
SCOPE
1.1 These test methods cover the determination of the in-place density of unhardened and hardened 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 7 Test Method B---Backscatter 8
1.3 The values stated in inch-pound units are to be regarded as the standard. The SI equivalents of inch-pound units may be approximate.
1.4 This standard does not purport to address all of the safety problems, 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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:C1040–93 (Reapproved 2000)
Standard Test Methods for
Density of Unhardened and Hardened Concrete In Place By
Nuclear Methods
This standard is issued under the fixed designation C 1040; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2 These test methods are suitable for control and for
assisting in acceptance testing during construction, for evalu-
1.1 These test methods cover the determination of the
ation of concrete quality subsequent to construction, and for
in-place density of unhardened and hardened concrete by
research and development.
gamma radiation. For notes on the nuclear test see Appendix
X1.
NOTE 1—Care must be taken when using these test methods in
1.2 Two test methods are described, as follows:
monitoring the degree of consolidation, which is the ratio of the actual
density achieved to the maximum density attainable with a particular
Section
concrete.The test methods presented here are used to determine the actual
Test MethodA—Direct Transmission 7
density. A density measurement, by any test method, is a function of the
Test Method B—Backscatter 8
components of the concrete and may vary, to some extent, in response to
the normal, acceptable variability of those components.
1.3 The values stated in inch-pound units are to be regarded
as the standard.The SI equivalents of inch-pound units may be 3.3 Test results may be affected by reinforcing steel, by the
approximate. chemical composition of concrete constituents, and by sample
1.4 This standard does not purport to address all of the heterogeneity. The variations resulting from these influences
safety concerns, if any, associated with its use. It is the are minimized by instrument design and by the user’s compli-
responsibility of the user of this standard to establish appro- ance with appropriate sections of the test procedure. Results of
priate safety and health practices and determine the applica- tests by the backscatter test method may also be affected by the
bility of regulatory limitations prior to use.
density of underlying material. The backscatter test method
exhibits spatial bias in that the apparatus’s sensitivity to the
2. Referenced Documents
material under it decreases with distance from the surface of
2.1 ASTM Standards:
the concrete.
C 29/C 29M Test Method for Unit Weight and Voids in
2 4. Apparatus
Aggregate
C 138 Test Method for Unit Weight, Yield, andAir Content 4.1 The exact details of construction of the apparatus may
(Gravimetric) of Concrete vary,buttheapparatusasawholeshallsatisfytherequirements
for system precision stated in 10.1. The system shall consist of
3. Significance and Use
the following:
3.1 These test methods are useful as rapid, nondestructive
4.1.1 Gamma Source—An encapsulated and sealed radio-
techniques for the in-place determination of the density of isotopic source, such as cesium-137 (see X1.2).
unhardened concrete. The backscatter test method is also
4.1.2 Detector—Any type of gamma detector, such as a
useful for the same purpose on hardened concrete. The Geiger-Müller tube, scintillation crystal, or proportional
fundamental assumptions inherent in the test methods are that
counter.
Compton scattering is the dominant interaction and that the 4.1.3 Probe—For direct transmission measurements, either
material under test is homogeneous.
thegammasourceorthedetectorshallbehousedinaprobefor
inserting in a preformed hole in the material to be tested. The
probe shall be marked in increments of 2 in. (50 mm) for tests
These test methods are under the jurisdiction of ASTM Committee C09 on
with probe depths from 2 to 12 in. (50 to 300 mm). The probe
ConcreteandConcreteAggregatesandarethedirectresponsibilityofSubcommittee
C09.45 on Roller-Compacted Concrete.
shall be so made mechanically, that when moved manually to
Current edition approved March 15, 1993. Published May 1993. Originally
the marked depth desired, it will be held securely in position at
published as C 1040 – 85. Last previous edition C 1040 – 85.
2 that depth.
Annual Book of ASTM Standards, Vol 04.02.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959, United States.
C1040
4.1.4 Readout Instrument—A suitable scaler or direct read- the necessary adjustments using the same mode of operation
out meter. and at the same depth (if using direct transmission) as that
4.1.5 Gage Housing—The source, detector, readout instru-
intendedfortesting.Arecommendedprocedureformakingthis
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
theprobe,forformingaholenormaltotheconcretesurfaceare
NOTE 4—Consolidationmaybeachievedbytheprocedureusedforunit
required. weight testing (Test Method C 138) or by other methods, such as spading
the concrete and then dropping the ends of the container alternately on a
4.1.8 Calibration Adjustment Container— The container
rigid surface.
shall be rigid and watertight, with minimum inside dimensions
large enough to allow the calibration curve adjustment proce-
5.2.3 Strike off the container with strike-off plate or bar.
dure (5.2) to be followed with no effect of the finite size of the
Take care to make the concrete surface flat and flush with the
container on the instrument’s responses. The volume of the
container edges.
container shall be established following the procedure outlined
in Test Method C 29/C 29M. NOTE 5—A ⁄16 in. (1.6 mm) average difference between the concrete
surface and the container edges in a 6 in. (150 mm) deep container will
NOTE 2—For backscatter measurements, a container 18 by 18 by 6 in.
produce a 1.0 % error in the weighed density of the concrete.
(450 by 450 by 150 mm) will meet this requirement for most equipment
currently available commercially. For 2-in. (50-mm) depth direct trans- 5.2.4 Weigh the concrete in the container to the nearest 0.5
mission measurements, a container 24 by 24 by 4 in. (600 by 600 by 100
lb (250 g) and determine the weighed density as follows:
mm) will meet this requirement.
W
c
W 5 (1)
4.1.9 Scale—The scale shall be accurate to within 0.5 lb
V
(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 weight
where:
of the calibration adjustment container empty, to the weight of
3 3
3 3 W = weighed density of concrete, lb/ft (kg/m ),
the measure plus the contents at 160 lb/ft (2600 kg/m ).
W = weight of the concrete, lb (kg), and
c
4.1.10 Strike-Off Plate or Bar—This shall be a flat metal or
3 3
V = volume of the container, ft (m ).
glass plate or metal bar with a length at least 2 in. (50 mm)
5.2.5 Immediately take three automatically timed direct
greater than the length, width, or diameter of the calibration
transmission or backscatter readings with the instrument cen-
adjustment container.The strike-off must be rigid, straight, and
tered on the surface of the concrete in the container. Rotate the
smooth enough to finish the concrete surface flat and flush with
base of the instrument 90° around the vertical axis, with
the edges of the calibration adjustment container.
subsequent rotations of 180 and 270° from the original
position. Obtain three additional automatically timed counts at
5. Calibration
each position. The instrument must be centered over the
5.1 Calibration curves are established by determining the
surface of the concrete in each rotated position to prevent edge
nuclear count rate of each of several materials at different and
effects on the instrument reading.
known densities, plotting the count rate (or count ratio) versus
5.2.6 Using the applicable calibration curve, determine the
each known density, and placing a curve through the resulting
density from the average of the 12 counts obtained in 5.2.5.
points. The method used to establish the curve must be the
5.2.7 Determine the difference between the two density
same as that used to determine the density. The materials used
readings obtained in 5.2.4 and 5.2.6.
for calibration must be of uniform density.
5.2.8 Repeat 5.2.2-5.2.7 on two additional concrete mixes
NOTE 3—Calibrationcurvesaresuppliedbygagemanufacturers,orcan
of the same proportions. Determine the adjustment factor by
be established using blocks of known density or prepared containers of
averaging the three values obtained in 5.2.7 and 5.2.8. If one of
uniform, unchanging material compacted to known densities. Materials
considered satisfactory for use in blocks include granite, aluminum, chalk, thethreevaluesdiffersfromtheaveragebymorethan1.5lb/ft
limestone, and magnesium.
(24 kg/m ), discard it as a statistical outlier and recalculate the
adjustment factor as the average of the remaining two values.
5.2 Adjusting Calibration Curves—Prior to use, adjust the
instrument’s calibration curve, if necessary, to compensate for 5.2.9 Use the adjustment factor determined in 5.2.8 to plot
a corrected count-rate calibration curve which shall be parallel
chemical composition effects. Such an adjustment is necessary
wheneverthechemicalcompositionoftheconcretetobetested to the original calibration curve and offset by the amount
indicated in 5.2.8. Alternatively, the value of the adjustment
differs significantly from that for which the calibration curve
was established. An adjustment is also necessary if the testing factor shall be attached to the instrument and applied to all
equipment has been changed. Adjustment is particularly im- density determinations arrived at from an original (unadjusted)
portant for backscatter test method measurements. Determine calibration curve.
C1040
NOTE 6—In some circumstances, for example, where chemical compo-
of the underlying (original) concrete 1 to 2 in. (25 to 50 mm)
sition changes are minimal, calibration curve adjustments may be estab-
down over a small area before placement of the overlay.
lished on permanent, uniform, hardened concrete blocks.
7.2 Smooth the surface with a wood float. If necessary, use
the guide plate and hole-forming device (4.1.7) to make a hole
6. Standardization
slightly larger than the probe and perpendicular to the surface.
6.1 Standardization of the equipment on the reference stan-
In some concretes, the probe may be inserted directly into the
dard is required at the start of each day and whenever test
concrete without the use of the guide plate and hole-forming
measurements are suspect.
device.
NOTE 7—In some older instrument models, count rates are strongly 7.3 Insert the probe so that the side of the probe facing the
influenced by the ambient temperature; frequent standardization may be
center of the gage is in intimate contact with the side of the
necessary.
hole. Keep all other radioactive sources at such a distance from
6.2 Warm-up time shall be in accordance with the manufac- the gage that the readings will not be affected.
turer’s recommendations.
NOTE 8—Thirty feet (10 m) is the recommended minimum distance
6.3 Take at least five readings on the reference standard,
from other nuclear density gages.
more if recommended by the manufacturer, or take one 4 min
7.4 Use the same warm-up time as in standardization. Take
or longer count if the instrument is equipped with automatic
automatically timed readings, for a minimum of 1 min, and
standard count storage.
determine the in-place density from the adjusted calibration
6.4 Ifmorethanoneoftheindividualreadingsisoutsidethe
curve. Alternatively, determine the in-place density from the
limit set by Eq 2, repeat the standardization. If the second
unadjusted calibration curve and then apply the calibration
attempt does not satisfy Eq 2, check the system for a malfunc-
adjustment factor (5.2.9). If the instrument has a direct reading
tion. If no malfunction is found, establish a new N (average
o
display which is not programmed to apply the calibration
count) by taking the average of a minimum of 10 counts on the
adjustment factor (5.2.8), correct the displayed density by
reference standard.
applying that factor.
|N 2N | , 1.96 N (2)
=
s o o
TEST METHOD B—BACKSCATTER (FOR
where:
UNHARDENED OR HARDENED CONCRETE)
N = count currently measured in checking the instrument
s
operation, and
8. Procedure
N = average count previously established on the reference
o
8.1 Select a test location such that, when the gage is placed
standard.
in test position:
In instruments where the count has been prescaled, that is,
8.1.1 Any point on the source-detector axis shall be at least
divided by a constant factor k before it is displayed, Eq 2 shall
9 in. (230 mm) from any pavement edge or object, and
be replaced by the following:
8.1.2 No reinforcing steel with less than 3 in. (75 mm) of
|N 2N | , 1.96 N /k (3) concrete cover shall lie directly under the source - detector
=
s o o
axis, except as indicated in Note 9.
6.4.1 If automatic standard count storage is used and the
newly established count is outside the limit set by Eq 2, repeat
NOTE 9—The user may find that certain instrument models and oper-
the standardization. ating modes allow gages to operate over steel with as little as 1 ⁄2 in. (38
mm) of concrete cover.
6.4.2 If the second attempt does not satisfy Eq 2, check the
system for a malfunction.
8.2 Prepare the test site in the following manner:
6.4.3 If no malfunction is found, establish a newN equal to
o 8.2.1 On unhardened concrete, smooth the surface with a
the average count found in 6.4.2.
wood float.
6.5 IfanewN differsbymorethan10 %fromthestandard
8.2.2 For best results on hardened concrete, find as smooth
o
count at which the calibration curve (5.1) was established,
a surface as possible. Remove all loose material. The maxi-
recalibrate the instrument. 1
mum void beneath the gage shall not exceed ⁄8in. (3 mm). Use
fine sand to fill these voids and smooth the surface with a rigid
TEST METHOD A—DIRECT TRANSMISSION (FOR
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.