ASTM C684-99
(Test Method)Standard Test Method for Making, Accelerated Curing, and Testing Concrete Compression Test Specimens
Standard Test Method for Making, Accelerated Curing, and Testing Concrete Compression Test Specimens
SCOPE
1.1 This test method covers four procedures for making, curing, and testing specimens of concrete stored under conditions intended to accelerate the development of strength. The four procedures are: Procedure A-Warm Water Method, Procedure B-Boiling Water Method, Procedure C-Autogenous Curing Method, and Procedure D-High Temperature and Pressure Method.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information purposes only.
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. See Section 9 and 14 for specific warnings and precautions.
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Standards Content (Sample)
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Designation: C 684 – 99
Standard Test Method for
Making, Accelerated Curing, and Testing Concrete
Compression Test Specimens
This standard is issued under the fixed designation C 684; 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 C 617 Practice for Capping Cylindrical Concrete Speci-
mens
1.1 This test method covers four procedures for making,
C 1231 Practice for Use of Unbonded Caps in Determina-
curing, and testing specimens of concrete stored under condi-
tion of Compressive Strength of Hardened Concrete Cyl-
tions intended to accelerate the development of strength. The
inders
four procedures are: Procedure A—Warm Water Method,
D 3665 Practice for Random Sampling of Construction
Procedure B—Boiling Water Method, Procedure
Materials
C—Autogenous Curing Method, and Procedure D—High
E 105 Practice for Probability Sampling of Materials
Temperature and Pressure Method.
E 122 Practice for Choice of Sample Size to Estimate a
1.2 The values stated in SI units are to be regarded as
Measure of Quality for a Lot or Process
standard. The values given in parentheses are provided for
E 141 Practice for Acceptance of Evidence Based on the
information purposes only.
Results of Probability Sampling
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 There are no terms in this standard that require new or
priate safety and health practices and determine the applica-
other than dictionary definitions.
bility of regulatory limitations prior to use. See Section 9 and
Note 9 and Note 14 for specific warnings and precautions.
4. Summary of Test Method
4.1 Concrete specimens are exposed to accelerated curing
2. Referenced Documents
conditions that permit the specimens to develop a significant
2.1 ASTM Standards:
portion of their ultimate strength within a time period ranging
C 31/C 31M Practice for Making and Curing Concrete Test
from 5 to 49 h, depending upon the procedure that is used.
Specimens in the Field
Procedures A and B utilize storage of specimens in heated
C 39 Test Method for Compressive Strength of Cylindrical
water at elevated curing temperatures without moisture loss.
Concrete Specimens
2 The primary function of the moderately heated water used in
C 172 Practice for Sampling Freshly Mixed Concrete
Procedure A is to serve as insulation to conserve the heat
C 177 Test Method for Steady-State Heat Flux Measure-
generated by hydration. The temperature level employed in
ments and Thermal Transmission Properties by Means of
3 Procedure B provides thermal acceleration. Procedure C in-
the Guarded-Hot-Plate Apparatus
volves storage of specimens in insulated curing containers in
C 192/C 192M Practice for Making and Curing Concrete
2 which the elevated curing temperature is obtained from heat of
Test Specimens in the Laboratory
hydration of the cement. The sealed containers also prevent
C 470 Specification for Molds for Forming Concrete Test
2 moisture loss. Procedure D involves simultaneous application
Cylinders Vertically
of elevated temperature and pressure to the concrete using
special containers. Sampling and testing procedures are the
This test method is under the jurisdiction of ASTM Committee C-9 on Concrete same as for normally cured specimens (see Practice C 172 and
and Concrete Aggregates and is the direct responsibility of Subcommittee C09.61 on
Test Method C 39, respectively).
Testing for Strength.
Current edition approved Nov. 10, 1999. Published February 2000. Originally
published as C 684 – 71 T. Last previous edition C 684 – 96.
2 4
Annual Book of ASTM Standards, Vol 04.02. Annual Book of ASTM Standards, Vol 04.03.
3 5
Annual Book of ASTM Standards, Vol 04.06. Annual Book of ASTM Standards, Vol 14.02.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
C684–99
4.2 Important characteristics of these procedures are shown 7.2 Molds:
in Table 1.
7.2.1 Cylinder molds for test specimens used in Procedures
A, B, and C shall conform to Specification C 470. Paper molds
5. Significance and Use
are excluded. When specimens are to be tested without
5.1 The accelerated curing procedures provide, at the earli-
capping, use only reusable molds with machined end plates
est practical time, an indication of the potential strength of a
that can be securely connected to both top and bottom of the
specific concrete mixture. These procedures also provide
mold. The end plates shall produce specimens with bearing
information on the variability of the production process for use
surfaces that are plane within 0.05 mm (0.002 in.) and whose
in quality control.
ends do not depart from perpendicularity to the axis of the
5.2 The accelerated early strength obtained from any of the
cylinder by more than 0.5° (approximately equivalent to 10
procedures in this test method can be used to evaluate concrete
mm/m ( ⁄8 in. in 12 in.). When assembled, the mold assembly
strengths in the same way conventional 28-day strengths have
is sufficiently tight to permit the filled mold to be turned from
been used in the past, with suitable changes in the expected
the vertical filling position to a horizontal curing position
strength values. Since the practice of using strength values
without loss of mortar or damage to the test specimen.
obtained from standard-cured cylinders at 28 days is long
7.2.2 Cylinder molds for Procedure D shall conform to the
established and widespread, the results of accelerated strength
following:
tests are often used to estimate the later-age strength under
7.2.2.1 Made of stainless steel,
standard curing. Such estimates should be limited to concretes
using the same materials and mixture proportions as those used
7.2.2.2 Equipped with removable top and bottom metal
for establishing the correlation. Appendix X2 provides a
plugs and O-ring seals,
procedure to estimate the 90 % confidence interval of the
7.2.2.3 Equipped with a heating element capable of raising
average later-age strength based on accelerated strength test
the concrete temperature within the mold to 150 6 3°C (300 6
results.
5°F) within 30 6 5 min, and are capable of maintaining this
5.3 Correlation between accelerated strength and strength
temperature throughout the time required by the test procedure,
achieved at some later age by using conventional curing
7.2.2.4 Equipped with devices to measure the temperature
methods depends upon the materials comprising the concrete,
within each mold to ascertain that the temperature of the
the mixture proportions, and the specific accelerated test
concrete satisfies the temperature requirements stated herein,
procedure.
and
5.4 The user shall choose which procedure to use on the
7.2.2.5 Equipped with a companion loading component
basis of experience and local conditions. These procedures, in
capable of maintaining a pressure of 10.3 MPa 6 0.2 MPa
general, will be practical when a field laboratory is available to
(1500 6 25 psi) on the concrete during the curing period.
house the curing containers and the testing equipment to
measure compressive strength within the specified time limits.
7.3 Curing Apparatus:
7.3.1 Accelerated Curing Tank for Procedures A and B:
6. Interferences
7.3.1.1 The tank is of any configuration suitable for the
6.1 When wet sieving of the concrete sample is required
number of cylinders to be tested. Arrange the cylinders in any
prior to molding the test specimens due to maximum aggregate
configuration that provides a clearance of at least 50 mm (2 in.)
size limitations (such as Procedure D, which is limited to 25
between the side of each cylinder and the side of the tank, and
mm maximum), consider the effect of wet sieving on the air
at least 100 mm (4 in.) between adjacent cylinders. Maintain
content and strength of the test specimens.
the water level at least 100 mm (4 in.) above the tops of the
cylinders.
7. Apparatus
7.1 Equipment and small tools for fabricating specimens,
NOTE 1—Provision for an overflow pipe is a convenience in controlling
measuring slump, and determining air content shall conform to
the maximum depth of water. A number of different tanks have been used
Practice C 31/C 31M. successfully. Guidelines are given in Appendix X1.
TABLE 1 Characteristics of Accelerated Curing Procedures
Accelerated Curing Age Accelerated Duration of
Source of Strength Age at
Procedure Molds Temperature Curing Accelerated
Acceleration Testing
°C (°F) Begins Curing
A. Warm Water reusable or single-use heat of hydration 35 (95) immediately after 23.5 h 6 30 min 24 h 6 15 min
casting
B. Boiling Water reusable or single-use boiling water boiling 23 h 6 30 min after 3.5 h 6 5 min 28.5 h 6 15 min
casting
C. Autogenous single-use heat of hydration initial concrete immediately after 48 h 6 15 min 49 h 6 15 min
temperature casting
augmented by
heat of hydration
A
D. High-Temperature reusable external heat and 150 (300) immediately after 5h 6 5 min 5.25 h 6 5 min
and Pressure pressure casting
A
Add 30 min if capping with sulfur compound is used.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
C684–99
7.3.1.2 Equip the tank with environmental control ele- 9.2 Observe the additional safety measures indicated when
ment(s) capable of: (1) providing the specified water tempera- using Procedure B to prevent scalding or other burns resulting
ture, (2) maintaining the water temperature within 63°C from the use of boiling water as a curing medium.
(65°F) of the specified value at any point in the water, and (3) 9.3 Observe the additional safety measures indicated when
limiting the temperature drop, after immersion of specimens, to using Procedure D to prevent injury due to the high tempera-
less than 3°C (5°F) and returning to the specified water ture and pressure used for curing.
temperature within 15 min. Thermometers or other temperature
10. Sampling
recording devices are required, independent of the thermostat,
to check the temperature of the water.
10.1 Determine the number of tests required from the
concrete lot(s) or process. Use a random or systematic plan that
NOTE 2—Depending upon the design features of the tank, insulation or
provides the number of tests needed to characterize the strength
mechanical agitation, or both, might be necessary to meet the specified
of the concrete used in the construction.
temperature requirements. Electrical immersion heaters controlled by a
thermostat are one suitable form of heating elements. For a particular
10.2 If the lot(s) or process is stratified into sublots, locate
procedure, the size of the heating element required will depend upon the
the samples using a stratified random procedure. If circum-
size of the tank and the number of specimens to be cured at one time.
stances dictate a non-stratified approach, use a random proce-
7.3.1.3 The plate supporting the specimens is perforated to dure.
permit circulation of the water.
NOTE 4—A stratified random sampling procedure can be implemented
7.3.1.4 A close fitting lid to reduce evaporation is required
by dividing each lot of concrete into a number of equal-sized sublots, and
for Procedure B but is optional for Procedure A.
randomly selecting a sample from each sublot. The number of sublots
7.3.2 Curing Container for Procedure C:
equals the number of samples that were scheduled to be taken from the lot.
7.3.2.1 The container consists of thermal insulation meeting For example, if the job requirements called for each 500 m of concrete to
be treated as a lot and that five samples be obtained from each lot to
heat retention requirements of 12.2.1 and closely surrounding
determine compressive strength, divide the lot into five equal-sized
the concrete specimen.
sublots of 100 m each. Randomly obtain one sample from each sublot.
7.3.2.2 The container is capable of being opened to permit
Test results from the five samples obtained in this manner provide
insertion and withdrawal of the specimen and has an outer 3
unbiased estimates of the compressive strength of the 500 m lot. This is
casing and inner liner to protect the insulation from mechanical
the most practical approach to ensure that the samples obtained include the
damage. entire range of concrete in the production process. If unequal size sublots
occur due to the construction process, weighting of the test results may be
7.3.2.3 The container has a maximum-minimum recording
appropriate to maintain the fairness and defensibility of the sampling
thermometer which is not insulated from the concrete specimen
procedure.
(see Note 10).
NOTE 5—Practice D 3665 contains a table of random numbers, includ-
7.3.2.4 The container has a lid or other means to provide
ing instructions for use. Practices E 105, E 122, and E 141 contain
secure closure during the specified curing period. The lid
additional information concerning sampling practices.
includes a heat seal that satisfies the requirements of 12.2.2.
10.3 Sample the freshly mixed concrete in accordance with
7.3.2.5 The container is capable of holding either one or two
Practice C 172. Record in the job records the location at which
specimens.
the sampled batch is used in the structure.
NOTE 3—Examples of suitable containers are included in Appendix X1.
Any configuration is acceptable provided it meets the performance 11. Preparation of Apparatus
requirements of 12.2.
11.1 Methods A and B:
7.3.3 Curing Apparatus for Procedure D:
11.1.1 Activate the environmental control elements at least
7.3.3.1 The curing apparatus consists of a loading system to
1 h prior to the start of a scheduled test to allow the temperature
apply the specified pressure to the concrete specimens and
of the water and equipment to stabilize.
special molds to maintain the concrete specimens at the
11.2 Method C:
specified temperature during the curing period. The curing
11.2.1 Conduct the proving tests specified in Section 12
apparatus can be of any configuration suitable for the number
prior to scheduling tests.
of cylindrical specimens to be tested. Appendix X1 describes a
11.3 Method D:
successful apparatus designed for curing three specime
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