ASTM C1579-06
(Test Method)Standard Test Method for Evaluating Plastic Shrinkage Cracking of Restrained Fiber Reinforced Concrete (Using a Steel Form Insert)
Standard Test Method for Evaluating Plastic Shrinkage Cracking of Restrained Fiber Reinforced Concrete (Using a Steel Form Insert)
SIGNIFICANCE AND USE
The test method is intended to evaluate the effects of evaporation, settlement, and early autogenous shrinkage on the plastic shrinkage cracking performance of fiber reinforced concrete up to and for some hours beyond the time of final setting (See Terminology C 125).
The measured values obtained from this test may be used to compare the performance of concretes with different mixture proportions, concretes with and without fibers, concretes containing various amounts of different types of fibers, and concretes containing various amounts and types of admixtures. For meaningful comparisons, the evaporative conditions during test shall be sufficient to produce an average crack width of at least 0.5 mm in the control specimens (2, 5) (See Note 2). In addition, the evaporation rate from a free surface of water shall be within ± 5 % for each test.
Note 2—To achieve evaporation rates that result in a crack of at least 0.5 mm in the control specimens, it may be necessary to use an evaporation rate higher than that discussed in Note 1.
This method attempts to control atmospheric variables to quantify the relative performance of a given fresh concrete mixture. Since many other variables such as cement fineness, aggregate gradation, aggregate volume, mixing procedures, slump, air content, concrete temperature and surface finish can also influence potential cracking, attention shall be paid to keep these as consistent as possible from mixture to mixture.
SCOPE
1.1 This test method compares the surface cracking of fiber reinforced concrete panels with the surface cracking of control concrete panels subjected to prescribed conditions of restraint and moisture loss that are severe enough to produce cracking before final setting of the concrete.
1.2 This test method can be used to compare the plastic shrinkage cracking behavior of different concrete mixtures containing fiber reinforcement.
1.3 The values stated in SI units are to be regarded as 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. ( Warning- fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure.)
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Standards Content (Sample)
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Designation:C1579–06
Standard Test Method for
Evaluating Plastic Shrinkage Cracking of Restrained Fiber
Reinforced Concrete (Using a Steel Form Insert)
This standard is issued under the fixed designation C1579; 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 (ϵ) indicates an editorial change since the last revision or reapproval.
1. Scope C670 Practice for Preparing Precision and Bias Statements
for Test Methods for Construction Materials
1.1 This test method compares the surface cracking of fiber
C995 Test Method for Time of Flow of Fiber-Reinforced
reinforced concrete panels with the surface cracking of control
Concrete Through Inverted Slump Cone
concrete panels subjected to prescribed conditions of restraint
and moisture loss that are severe enough to produce cracking
3. Summary of Test Method
before final setting of the concrete.
3.1 Panels of control concrete and fiber reinforced concrete
1.2 This test method can be used to compare the plastic
are prepared in a prescribed manner and are exposed to
shrinkage cracking behavior of different concrete mixtures
controlled drying conditions after finishing. The drying condi-
containing fiber reinforcement.
tions (See Note 1) are intended to be severe enough to induce
1.3 The values stated in SI units are to be regarded as the
plastic shrinkage cracking in test panels made of control
standard.
concrete. The evaporation rate from a free water surface is
1.4 This standard does not purport to address all of the
monitored by pans placed next to the panels in the environ-
safety concerns, if any, associated with its use. It is the
mental chamber.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
NOTE 1—An important parameter in this method is the rate of evapo-
bility of regulatory limitations prior to use. (Warning— fresh rative water loss, which is controlled by the atmospheric conditions
surrounding the test specimens. Since the concrete specimens will not
hydraulic cementitious mixtures are caustic and may cause
always have the same rate of water evaporation as the pan of water (due
chemical burns to skin and tissue upon prolonged exposure.)
toevaporativeandbleedingeffects),therateofevaporationof1.0kg/m ·h
from the pan of water represents the minimum evaporation rate that must
2. Referenced Documents
be attained for this test (1). The moisture loss from the concrete test
2.1 ASTM Standards:
panels can also be monitored and reported, however, the rate of evapora-
C125 Terminology Relating to Concrete and Concrete Ag-
tion from the free surface of the water in the pan is the parameter that
gregates should be used to quantify the drying environment.
C143/C143M Test Method for Slump of Hydraulic-Cement
3.2 The test is terminated at the time of final setting of the
Concrete
concrete determined in accordance with Test Method C403/
C192/C192M Practice for Making and Curing Concrete
C403M. At 24 h from initial mixing, the average crack width
Test Specimens in the Laboratory
is determined.
C403/C403M Test Method for Time of Setting of Concrete
3.3 A cracking reduction ratio (CRR) is computed from the
Mixtures by Penetration Resistance
average crack width for the fiber-reinforced concrete panels
and the average crack width for the control concrete panels.
4. Significance and Use
This test method is under the jurisdiction of ASTM Committee C09 on
Concrete and ConcreteAggregates and is the direct responsibility of Subcommittee 4.1 The test method is intended to evaluate the effects of
C09.42 on Fiber-Reinforced Concrete.
evaporation, settlement, and early autogenous shrinkage on the
Current edition approved Feb. 15, 2006. Published March 2006. DOI: 10.1520/
plastic shrinkage cracking performance of fiber reinforced
C1579-06.
Section on Safety Precautions, Manual of Aggregate and Concrete Testing,
Annual Book of ASTM Standards, Vol. 04.02.
3 4
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Withdrawn. The last approved version of this historical standard is referenced
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM on www.astm.org.
Standards volume information, refer to the standard’s Document Summary page on The boldface numbers in parentheses refer to the list of references at the end of
the ASTM website. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
C1579–06
concrete up to and for some hours beyond the time of final aggregate gradation, aggregate volume, mixing procedures,
setting (See Terminology C125). slump, air content, concrete temperature and surface finish can
4.2 The measured values obtained from this test may be alsoinfluencepotentialcracking,attentionshallbepaidtokeep
used to compare the performance of concretes with different these as consistent as possible from mixture to mixture.
mixture proportions, concretes with and without fibers, con-
5. Apparatus
cretes containing various amounts of different types of fibers,
and concretes containing various amounts and types of admix-
5.1 Molds:
tures. For meaningful comparisons, the evaporative conditions
5.1.1 For maximum coarse aggregate size equal to or less
duringtestshallbesufficienttoproduceanaveragecrackwidth
than 19 mm, use a mold with a depth of 100 65mmand
of at least 0.5 mm in the control specimens (2, 5) (See Note 2).
rectangulardimensionsof355610mmby560615mm(See
In addition, the evaporation rate from a free surface of water
Fig. 1). The mold can be fabricated from metal, plastic, or
shall be within6 5 % for each test.
plywood.
NOTE 2—To achieve evaporation rates that result in a crack of at least
NOTE 3—If plywood is used for molds, the plywood should have low
0.5 mm in the control specimens, it may be necessary to use an
moisture absorption. The mold should be constructed to be lightweight
evaporation rate higher than that discussed in Note 1.
and stiff. The molds, when properly constructed, should last for approxi-
mately 50 uses.
4.3 This method attempts to control atmospheric variables
to quantify the relative performance of a given fresh concrete 5.1.2 This test method is designed for aggregate less than or
mixture. Since many other variables such as cement fineness, equal to 19 mm. For coarse aggregate greater than 19 mm, the
FIG. 1 Specimen and Stress Riser Geometry (4, 5)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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C1579–06
environmental chamber designed for this test method (See Fig. 3)orthe
depth of the mold shall be at least 65 mm plus at least 2 times
pans can be placed downstream from panels in a fan box (See Fig. 2).
the maximum coarse aggregate size.
5.2 Stress Riser and Internal Restraints—The internal re-
5.9 Scale—If the rate of moisture loss from test panels is
straints and stress riser shall be bent from one piece of sheet
required by the specifier of tests, weigh test panels with a scale
metal, as illustrated in Fig. 1, or made from a solid piece of
having a capacity of at least 100 kg and accurate to within
steel. The sheet metal shall have a thickness of 1.26 0.05 mm
0.1 % of the test load. Weigh the evaporation rate monitoring
(18 gauge) (See Fig. 1 and Ref 2). Two 32 6 1 mm high
pans with a balance or scale having a capacity of at least 3 kg
restraints are placed 906 2 mm inward from each end of the
and accurate to within 5 g.
mold. The central stress riser is 646 2 mm high and serves as
5.10 Crack Measurement Tool—Optical hand-held micro-
an initiation point for cracking. This sheet metal stress riser
scope,crackcomparator,orimageanalysissystemcanbeused.
with internal restraints shall fit at the bottom of the mold.
The measurement tool should be capable of measuring crack
5.2.1 Use form release oil to coat the metal insert and mold
width to at least the nearest 0.05 mm. If an automated image
sides to reduce bond with concrete. The insert and mold are
analysis system is used, it should be demonstrated to provide
considered to be properly oiled when the entire surface is
an accurate measurement. To demonstrate the accuracy of the
coated and excess oil has been removed with a clean, dry rag.
measurement, the system shall be used to measure a 0.5 mm
5.3 Variable Speed Fan(s)—The fan(s) used shall be ca- notch that is machined into a piece of steel and the reported
pable of achieving a wind speed of more than 4.7 m/s over the
notch width shall be within6 0.05 mm of the machined width.
entire test panel surface area.
6. Sampling, Test Specimens, and Test Units
5.4 Environmental Chamber—The use of a fan box in an
6.1 Test Panels—Cast test panels in accordance with the
environmental chamber is a method for producing a uniform
applicable provisions of Practice C192/C192M, using the same
airflow over the panel surface (See Fig. 2). A clear cover over
source of materials, preparation, mixing and finishing proce-
the panels will aid in obtaining uniform airflow and allow for
dures.
observation of cracking.Another method of producing uniform
6.2 Test Unit—A test unit is comprised of at least two
airflowistouseaspecificallydesignedenvironmentalchamber
control specimens and at least two fiber reinforced concrete
as shown in Fig. 3. A commercially available heater, humidi-
specimens with the same mixture proportions. A group of two
fier, and dehumidifier can be used to maintain the specified
control specimens has to be tested each time in order to
environmental condition. This test is conducted using either
determine the plastic shrinkage crack reduction of fiber rein-
apparatus shown in Fig. 2 or Fig. 3 by exposing the panels to
forced concrete.
anevaporationrateofatleast1.0kg/m ·h(SeeNote1).Forthe
standardtest,thetemperaturemustbemaintainedat3663°C,
7. Procedure
therelativehumiditymustbe30610 %,andthewindvelocity
7.1 Determinetheslumpofeachmixtureinaccordancewith
must be sufficient to maintain the minimum evaporation rate
Test Method C143/C143M. If the slump is too low for a
during the test.
concrete mixture containing fibers, use the time of flow
NOTE 4—Before casting the concrete panels, atmospheric variables in
through an inverted slump cone to measure workability in
the environmental facility should be checked to determine that the
accordance with Test Method C995.
necessary evaporative conditions can be achieved.Awind velocity of 4.7
7.2 Fabricate specimens for setting time determination in
m/s should be sufficient to achieve the minimum specified evaporation
accordance with Test Method C403/C403M. If fiber reinforced
rate, but a higher wind velocity may be needed to obtain sufficient average
crack width in some control panels. concrete cannot be wet sieved readily, use the control concrete
specimen to measure time of final setting of both the control
5.5 Sensors—Use temperature, humidity, and wind velocity
and the fiber-reinforced mixtures. Place the time of setting
sensors to measure ambient air and concrete surface tempera-
specimensintheairstreamsothattheyareexposedtothesame
ture to the nearest 0.5 °C, relative humidity to the nearest 1 %,
environmental conditions as the plastic shrinkage panels.
and air speed to the nearest 0.1 m/s.
7.3 Fill the panel molds using one layer. Consolidate the
5.6 Vibrating Platform—Any device that can fully consoli-
concrete with external vibration until the concrete is approxi-
datethetestpanelthatmeetsminimumfrequencyrequirements
mately level with the top of the mold. Screed each specimen
as stated in Practice C192/C192M for an external vibrator is
perpendicular to the stress riser three times.
suitable.
7.4 After screeding, trowel specimens using a predeter-
5.7 Surface Finishing Equipment—An angle iron screed
mined number of passes. If moisture loss from the panel is to
shall be used for the concrete after vibration. A magnesium,
be determined, remove any waste concrete adhering to the
steel, or wood trowel shall be used for finishing the surface of
outside of the mold and weigh each panel while in the mold.
the specimen after screeding.
7.5 Place a fiber reinforced concrete mixture panel and
5.8 Monitoring Pan—A pan suitable for exposing water to
control mixture panel in the environmental chamber down-
theairstreamforeachconcretetestpanelisrequired.Thesides
stream from the fan(s) (See arrangements in Figs. 2 and 3).
of the pan shall be vertical. The pan shall be of sufficient size
7.6 Turn on the fan(s), which have been preset to achieve
to expose at least 0.16 0.01 m of water to the air stream.The
the air speed to obtain the required evaporative conditions (See
exposed lip of the pan shall not extend more than 5 mm above
Note 4). The evaluation of cracking commences at this time.
the water level at the start of the test.
7.7 At the start of the test and at 30-min intervals, record air
NOTE 5—The test panels and monitoring pans can be placed in an temperature, relative humidity, and air flow speed at a location
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Please contact ASTM International (www.astm.org) for the latest information.
C1579–06
FIG. 2 Example of Fan Box to Maintain Environmental Conditions (2) (Not to Scale)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
C1579–06
FIG. 3 Example of Chamber to Maintain Environmental Conditions (4)
100 6 5 mm above each panel surface. If required by the and the time interval between successive weighings (See Note
specifier of tests, record the time at which cracking is first 6). The test is not valid if the average evaporation rate is less
observed for each panel surface. Perform penetration tests at than 1.0 kg/m ·h.
regular time intervals according to Test Method C403/C403M.
NOTE 6—Adjustments to wind velocity should be made if necessary to
Continue recording the environmental variables until the time
maintain the evaporation rate at the required level. It is suggested that the
of final setting.
monitoring pans be placed on scales in the air stream for continuous
monitoring
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