ASTM C1150-96

Standard Test Method for the Break-Off Number of Concrete (Withdrawn 2002)

SCOPE
1.1 This test method covers determination of the break-off number of hardened concrete in test specimens or structures, by measuring the force required to cause failure of a pre-cast or drilled core specimen loaded as a cantilever.
1.2 The values stated in SI units are to be regarded as the standard.
1.3 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.

General Information

• Status: Withdrawn
• Publication Date: 09-May-1996
• Withdrawal Date: 09-Jan-2002
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.64 - Nondestructive and In-Place Testing

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: C 1150 – 96
Standard Test Method for
The Break-Off Number of Concrete
This standard is issued under the fixed designation C 1150; 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
1.1 This test method covers determination of the break-off
number of hardened concrete in test specimens or structures,
by measuring the force required to cause failure of a pre-cast or
drilled core specimen loaded as a cantilever.
1.2 The values stated in SI units are to be regarded as the
standard.
1.3 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 appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
E 178 Practice for Dealing with Outlying Observations
C 670 Practice for Preparing Precision and Bias Statements
for Test Methods for Construction Materials
C 823 Practice for Examination and Sampling of Hardened
Concrete in Constructions
3. Summary of Test Method
3.1 The principle of the break-off test is illustrated in Fig. 1.
A plastic sleeve with an annular seating ring is inserted in fresh
concrete to form a cylindrical test specimen and a counter bore.
After the concrete has hardened, the sleeve is removed and a
force is applied at the uppermost section of the cylinder so as
to break the cylindrical test specimen from the concrete mass.
The test result is reported as a break-off number, which is the
maximum pressure recorded by the gage measuring the hy-
draulic pressure in the loading mechanism. In hardened con-
crete, in cases where the plastic sleeve has not been installed,
a concrete coring machine with a specially shaped coring drill
FIG. 1 Schematic of Break-Off Test
bit may be used to drill a similarly shaped test specimen.
4. Significance and Use
This test method is under the jurisdiction of ASTM Committee C-9 on Concrete
4.1 The break-off number determined by this test method
and Concrete Aggregatesand is the direct responsibility of Subcommittee C09.64on
may be used to assess the in-place strength of concrete, and to
Nondestructive Testing of Concrete.
Current edition approved May 10, 1996. Published July 1996. Originally delineate zones, regions, or areas of varying quality or dete-
published as C 1150 – 90. Last previous edition C 1150 – 90e
riorated concrete in structures.
The break-off method is covered by a patent held by SINTEF, Norwegian
4.2 Prior to using this test method for determining in-place
Institute of Technology, Trondheim, Norway. Interested parties are invited to submit
strength, a correlation relationship between the break-off num-
information regarding the identification of acceptable alternatives to this patented
item to The Committee on Standards, ASTM Headquarters, 100 Barr Harbor Drive,
ber and the concrete strength should be established. Since such
West Conshohocken, PA 19428. Your comments will receive careful consideration
a correlation may vary with type and size of aggregates and
at a meeting of the responsible technical committee which you may attend.
method of specimen preparation, a relationship may be devel-
Annual Book of ASTM Standards, Vol 14.02.
Annual Book of ASTM Standards, Vol 04.02. oped to take these and other variables into account. This
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
C 1150
relationship must be established for each new combination of
concrete-making materials. In developing such relationships,
care must be taken to ensure that the break-off specimens and
the strength test specimens undergo similar curing histories up
to the time of the test.
NOTE 1—Published reports (1-8) by different researchers present their
experience in the use and evaluation of the break-off test equipment and
in establishing break-off strength correlation with compressive strength of
concrete.
4.3 The break-off test may be used to evaluate the in-place
concrete in order to:
4.3.1 Determine if formwork or reshoring can be removed,
4.3.2 Test if concrete meets break-off number specifications,
4.3.3 Determine when prestressing strands may be cut to
release the prestressing force,
4.3.4 Determine if concrete has sufficient strength to allow
post-tensioning to proceed,
4.3.5 Estimate efficiency of curing techniques, and
4.3.6 Evaluate the effects of exposure to environmental or
chemical attack.
4.4 When planning the break-off test and analyzing test
results, consideration should be given to (1) the normally
expected decrease of concrete strength with increasing height
within a given concrete placement in a structural element (see
9-11), and (2) locations with less favorable curing conditions
prior to form removal.
4.5 Break-off tests are not recommended for concrete with a
nominal maximum aggregate size greater than 25 mm. The
FIG. 2 Sleeve for Creating Test Specimen in Fresh Concrete
within test variability of the break-off test has been found to
increase in concrete with larger aggregate size (see (6) and
which produces a core with a circular counterbore at the
(11)).
surface with dimensions as shown in Fig. 3.
4.6 The cylindrical break-off specimens may be kept and
5.3 The loading mechanism shall consist of a tubular shaped
used for additional testing. The break-off test shall not be
fixture that fits into the counterbore, and a hydraulic piston
performed on concrete that is at a temperature of less
which when actuated applies a force at the top of the core,
than −5°C. Prior to starting a testing program the break-off
perpendicular to the longitudinal axis of the core.
tester must be calibrated according to the manufacturer’s
procedure (using the calibrator force gage and calibration
NOTE 2—The loading mechanism may include both a high and low
diagram provided with the test unit) to ensure a consistent measuring range capability to permit strength test of concrete over a wider
range. A correlation relationship must be developed using the range setting
relationship between the pressure gage reading and the force
that will be used during strength assessment.
applied by the loading mechanism.
5. Apparatus
5.1 The apparatus consists of a loading mechanism, a load
generating device, a load measuring instrument, a tubular
sleeve and seating ring of the dimensions shown in Fig. 2, a
tubular sleeve remover, and a gage for calibrating or adjusting
the loading system. The tubular sleeve shall be of a material
that is resistant to chemical attack by concrete. It shall be rigid
enough to maintain a reproducible size of test specimen. It
shall be coated with a release agent that is not reactive with
concrete prior to inserting it in the concrete. Plastic is an
acceptable sleeve material and automotive grease is a suitable
release agent.
5.2 For applications where tests are to be performed in
already hardened concrete, a diamond tipped drill bit is used,
The boldface numbers in parentheses refer to the list of references appended to
this test method. FIG. 3 Dimensions of Test Specimen Created by Core Drill
C 1150
5.4 The load generating device shall consist of a hydraulic is uniformly seated in the counterbore. Set the maximum
pump that is connected to the loading mechanism so that it is pressure indicator on the pressure gage to its zero value. Apply
possible to apply load (with smooth strokes of the pump) to the a gradual force to the specimen by means of the hydraulic
core until it breaks off. pump until the core breaks off. Use a loading rate that causes
5.5 The load measuring device shall consist of a pressure a break-off within 60 6 15 s from the start of loading. On the
gage to measure the hydraulic pressure applied to the loading pressure gage dial, read the maximum pressure required to
mechanism. The pressure gage shall have a maximum value break off the core and record the maximum reading as the
indicator. The pressure gage shall have a pressure range up to break-off number for the test specimen. In reading the maxi-
15 MPa (150 bars) and a least dial division not greater than 0.2 mum pressure, estimate to the nearest 0.1 MPa (1 bar).
MPa (2 bars). 7.3.2 Record the nature of the break at the base of the core.
Note whether the fracture surface includes the presence of
6. Sampling
large aggregate particles, reinforcing steel, and other abnor-
6.1 The break-off test locations shall be separated so that the malities, such as foreign inclusions, soft aggregate particles, or
center to center distance between test specimens is at least 150 excess
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