ASTM C1609/C1609M-05

Standard Test Method for Flexural Performance of Fiber-Reinforced Concrete (Using Beam With Third-Point Loading)

SCOPE
1.1 This test method evaluates the flexural performance of fiber-reinforced concrete using parameters derived from the load-deflection curve obtained by testing a simply supported beam under third-point loading using a closed-loop, servo-controlled testing system.
1.2 This test method provides for the determination of first-peak and peak loads and the corresponding stresses calculated by inserting them in the formula for modulus of rupture given in Eqn. 1. It also requires determination of residual loads at specified deflections, and the corresponding residual strengths calculated by inserting them in the formula for modulus of rupture given in Eqn. 1 (see Note 1). At the option of the specifier of tests, it provides for determination of specimen toughness based on the area under the load-deflection curve up to a prescribed deflection (see Note 1).Note 1
Residual strength is not a true stress but an engineering stress computed using simple engineering bending theory for linear elastic materials and gross (uncracked) section properties.Note 1
Specimen toughness expressed in terms of the area under the load-deflection curve is an indication of the energy absorption capability of the particular test specimen, and its magnitude depends directly on the geometry of the test specimen and the loading configuration.
1.3 UnitsThe 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.

General Information

• Status: Historical
• Publication Date: 14-Dec-2005
• ICS: 91.100.40 - Products in fibre-reinforced cement
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.42 - Fiber-Reinforced Concrete

Relations

• Replaced By: ASTM C1609/C1609M-06 - Standard Test Method for Flexural Performance of Fiber-Reinforced Concrete (Using Beam With Third-Point Loading)
• Effective Date: 15-Dec-2006
• Referred By: ASTM C1903-21 - Standard Specification for Precast Concrete Duct Bank
• Effective Date: 15-Dec-2005
• Referred By: ASTM C1812/C1812M-22 - Standard Practice for Design of Journal Bearing Supports to be Used in Fiber Reinforced Concrete Beam Tests
• Effective Date: 15-Dec-2005
• Referred By: ASTM C1399/C1399M-10(2015) - Standard Test Method for Obtaining Average Residual-Strength of Fiber-Reinforced Concrete (Withdrawn 2024)
• Effective Date: 15-Dec-2005
• Referred By: ASTM C1856/C1856M-17 - Standard Practice for Fabricating and Testing Specimens of Ultra-High Performance Concrete
• Effective Date: 15-Dec-2005
• Referred By: ASTM C1116/C1116M-23 - Standard Specification for Fiber-Reinforced Concrete
• Effective Date: 15-Dec-2005

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: C 1609/C 1609M – 05
Standard Test Method for
Flexural Performance of Fiber-Reinforced Concrete (Using
Beam With Third-Point Loading)
This standard is issued under the fixed designation C 1609/C 1609M; 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 priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 This test method evaluates the flexural performance of
fiber-reinforced concrete using parameters derived from the
2. Referenced Documents
load-deflection curve obtained by testing a simply supported
2.1 ASTM Standards:
beam under third-point loading using a closed-loop, servo-
C 31/C 31M Practice for Making and Curing Concrete Test
controlled testing system.
Specimens in the Field
1.2 This test method provides for the determination of
C 42/C 42M Test Method for Obtaining and Testing Drilled
first-peak and peak loads and the corresponding stresses
Cores and Sawed Beams of Concrete
calculated by inserting them in the formula for modulus of
C78 Test Method for Flexural Strength of Concrete (Using
rupture given in Eq 1. It also requires determination of residual
Simple Beam with Third-Point Loading)
loads at specified deflections, and the corresponding residual
C 125 Terminology Relating to Concrete and Concrete
strengths calculated by inserting them in the formula for
Aggregates
modulus of rupture given in Eq 1 (see Note 1).At the option of
C 172 Practice for Sampling Freshly Mixed Concrete
the specifier of tests, it provides for determination of specimen
C 192/C 192M Practice for Making and Curing Concrete
toughness based on the area under the load-deflection curve up
Test Specimens in the Laboratory
to a prescribed deflection (see Note 2).
C 823 Practice for Examination and Sampling of Hardened
NOTE 1—Residual strength is not a true stress but an engineering stress
Concrete in Constructions
computed using simple engineering bending theory for linear elastic
C 1140 Practice for Preparing and Testing Specimens from
materials and gross (uncracked) section properties.
Shotcrete Test Panels
NOTE 2—Specimen toughness expressed in terms of the area under the
load-deflection curve is an indication of the energy absorption capability
3. Terminology
of the particular test specimen, and its magnitude depends directly on the
geometry of the test specimen and the loading configuration. 3.1 Definitions—The terms used in this test method are
defined in Terminology C 125.
1.3 Units—The values stated in either SI units or inch-
3.2 Definitions of Terms Specific to This Standard:
pound units are to be regarded separately as standard. The
3.2.1 end-point deflection—thedeflectionvalueontheload-
values stated in each system may not be exact equivalents;
deflection curve equal to ⁄150 of the span, or a larger value as
therefore,eachsystemshallbeusedindependentlyoftheother.
specified at the option of the specifier of tests.
Combining values from the two systems may result in non-
3.2.2 first-peak load, P —the load value at the first point on
conformance with the standard.
the load-deflection curve where the slope is zero.
1.4 This standard does not purport to address all of the
3.2.3 first-peak deflection, d —the net deflection value on
safety concerns, if any, associated with its use. It is the
the load-deflection curve at first-peak load.
responsibility of the user of this standard to establish appro-
1 2
This test method is under the jurisdiction of ASTM Committee C09 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Concrete and ConcreteAggregates and is the direct responsibility of Subcommittee contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
C09.42 on Fiber-Reinforced Concrete. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Dec. 15, 2005. Published January 2006. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C 1609/C 1609M – 05
3.2.4 first-peak strength f —the stress value obtained when digitally and subsequently used to plot a load-deflection curve.
the first-peak load is inserted in the formula for modulus of Points termed first-peak, peak, and residual loads at specified
rupture given in Eq 1. deflectionsareidentifiedonthecurve,andareusedtocalculate
3.2.5 load-deflection curve—the plot of load versus net flexural performance parameters.
deflection of a flexural beam specimen loaded to the end-point
deflection.
5. Significance and Use
3.2.6 net deflection—thedeflectionmeasuredatmid-spanof
5.1 The first-peak strength characterizes the flexural behav-
a flexural beam specimen exclusive of any extraneous effects
ior of the fiber-reinforced concrete up to the onset of cracking,
due to seating or twisting of the specimen on its supports or
whileresidualstrengthsatspecifieddeflectionscharacterizethe
deformation of the support and loading system.
residual capacity after cracking. Specimen toughness is a
3.2.7 peak load, P —the maximum load on the load-
P
measureoftheenergyabsorptioncapacityofthetestspecimen.
deflection curve.
The appropriateness of each parameter depends on the nature
3.2.8 peak-load deflection, d —the net deflection value on
P
of the proposed application and the level of acceptable crack-
the load-deflection curve at peak load.
ing and deflection serviceability. Fiber-reinforced concrete is
3.2.9 peak strength, f —the stress value obtained when the
P
influencedindifferentwaysbytheamountandtypeoffibersin
peak load is inserted in the formula for modulus of rupture
the concrete. In some cases, fibers may increase the residual
given by Eq 1.
load and toughness capacity at specified deflections while
3.2.10 residual load, P —the load value correspond-
150,0.75
producing a first-peak strength equal to or only slightly greater
ing to a net deflection equal to ⁄600 of the span (or 0.75
than the flexural strength of the concrete without fibers. In
mm–0.03 in.) using a specimen with a depth of 150 mm (6 in.).
other cases, fibers may significantly increase the first-peak and
3.2.11 residual load, P —the load value correspond-
100,0.50
peak strengths while affecting a relatively small increase in
ing to a net deflection equal to ⁄600 of the span (or 0.50
residual load capacity and specimen toughness at specified
mm–0.02 in.) using a specimen with a depth of 100 mm (4 in.).
deflections.
3.2.12 residual load, P —the load value corresponding
150,3.0
5.2 The first-peak strength, peak strength, and residual
to a net deflection equal to ⁄150 of the span (3.0 mm–0.12 in.)
strengths determined by this test method reflect the behavior of
using a specimen with a depth of 150 mm (6 in.).
fiber-reinforced concrete under static flexural loading. The
3.2.13 residual load, P —the load value corresponding
100,2.0
absolute values of energy absorption obtained in this test are of
to a net deflection equal to ⁄150 of the span (2.0 mm–0.08 in.)
little direct relevance to the performance of fiber-reinforced
using a specimen with a depth of 100 mm (4 in.).
concrete structures since they depend directly on the size and
3.2.14 residual strength, f —the stress value obtained
150,0.75
shape of the specimen and the loading arrangement.
when the residual load P is inserted in the formula for
150,0.75
modulus of rupture given in Eq 1. 5.3 The results of this test method may be used for com-
3.2.15 residual strength, f —the stress value obtained paring the performance of various fiber-reinforced concrete
100,0.50
when the residual load P is inserted in the formula for mixtures or in research and development work. They may also
100,0.50
modulus of rupture given in Eq 1.
be used to monitor concrete quality, to verify compliance with
3.2.16 residual strength, f —the stress value obtained construction specifications, obtain flexural strength data on
150,3.0
when the residual load P is inserted in the formula for
fiber-reinforced concrete members subject to pure bending, or
150,3.0
modulus of rupture given in Eq 1. to evaluate the quality of concrete in service.
3.2.17 residual strength, f —the stress value obtained
100,2.0
NOTE 3—Theresultsobtainedusingonesizemoldedspecimenmaynot
when the residual load P is inserted in the formula for
100,2.0
correspond to the performance of larger or smaller molded specimens,
modulus of rupture given in Eq 1.
concrete in large structural units, or specimens sawn from such units.This
3.2.18 specimen toughness, T —the energy equivalent
150,3.0
difference may occur because the degree of preferential fiber alignment
totheareaundertheload-deflectioncurveuptoanetdeflection
becomes more pronounced in molded specimens containing fibers that are
relatively long compared with the cross-sectional dimensions of the mold.
of ⁄150 of the span (3.0 mm–0.12 in.) using a specimen with a
Moreover, structural members of significantly different thickness experi-
depth of 150 mm (6 in.).
encedifferentmaximumcrackwidthsforagivenmid-spandeflectionwith
3.2.19 specimen toughness, T —the energy equivalent
100,2.0
the result that fibers undergo different degrees of pull-out and extension.
totheareaundertheload-deflectioncurveuptoanetdeflection
of ⁄150 of the span (2.0 mm–0.08 in.) using a specimen with a
6. Apparatus
depth of 100 mm (4 in.).
6.1 Testing Machine—The testing machine shall be capable
4. Summary of Test Method
of servo-controlled operation where the net deflection of the
4.1 Molded or sawn beam specimens of fiber-reinforced center of the beam is measured and used to control the rate of
concrete are tested in flexure using a third-point loading increase of deflection. Testing machines that use stroke dis-
arrangement similar to that specified in Test MethodC78 but placement control or load control are not suitable for estab-
incorporating a closed-loop, servo-controlled testing system lishing the portion of the load-deflection curve immediately
and roller supports that are free to rotate on their axes. Load after first-peak.The loading and specimen support system shall
and net deflection are monitored and recorded to an end-point be capable of applying third-point loading to the specimen
deflection of at least ⁄150 of the span. Data are recorded and without eccentricity or torque. The fixtures specified in Test
plotted by means of an X-Y plotter, or they are recorded MethodC78 are suitable with the qualification that supporting
C 1609/C 1609M – 05
the stored data or from a plot of the data. In the latter case, use a plot scale
rollers shall be able to rotate on their axes and shall not be
similar to that recommended for an X-Y plotter.
placedingroovesorhaveotherrestraintsthatpreventtheirfree
rotation.
7. Sampling, Test Specimens, and Test Units
6.2 Deflection-Measuring Equipment—Devices such as
electronic transducers or electronic deflection gages shall be
7.1 General Requirements—The nominal maximum size of
located in a manner that ensures accurate determination of the aggregate and cross-sectional dimensions of test specimens
netdeflectionatthemid-spanexclusiveoftheeffectsofseating
shall be in accordance with Practice C 31/C 31M or Practice
or twisting of the specimen on its supports. One acceptable C 192/C 192M when using molded specimens, or in accor-
arrangement employs a rectangular jig, which surrounds the
dance with Test Method C 42/C 42M when using sawn speci-
specimen and is clamped to it at mid-depth directly over the mens, provided that the following requirements are satisfied:
supports (Figs. 1 and 2). Two electronic displacement trans-
7.1.1 Thelengthoftestspecimensshallbeatleast50mm(2
ducers or similar digital or analog devices mounted on the jig
in.) greater than three times the depth, and in any case not less
at mid-span, one on each side, measure deflection through
than 350 mm (14 in.).The length of the test specimen shall not
contact with appropriate brackets attached to the specimen.
be more than two times the depth greater than the span.
The average of the measurements represents the net deflection.
7.1.2 The width and depth of test specimens shall be at least
6.3 Data Recording System—An X-Y plotter coupled di-
three times the maximum fiber length.
rectly to electronic outputs of load and deflection is an
7.1.3 Whenthespecimensizeisnotlargeenoughtomeetall
acceptable means of obtaining the relationship between load
the requirements of 7.1-7.1.2, specimens of square cross-
and net deflection—that is, the load-deflection curve. A data
section large enough to meet the requirements shall be used.
acquisition system capable of digitally recording and storing
The three times maximum fiber length requirement for width
load and deflection data at a sampling frequency of at least 2.5
and depth may be waived at the option of the specifier of tests
Hz is an acceptable alternative.
to permit specimens with a width and depth of 150 mm (6 in.)
NOTE 4—For X-Yplotters, accurate determination of the area under the
when using fibers of length 50 to 75 mm(2to3 in.).
load-deflection curve and the loads corresponding to specified deflections
is only possible when the scales chosen for load and deflection are NOTE 5—The results of tests on beams with relatively stiff fibers, such
reasonably large.Aload scale chosen such that 25 mm (1 in.) corresponds as steel fibers, longer than one-third the width and depth of the beam may
to a flexural stress of the order of 1 MPa (150 psi), or no more than 20 % not be comparable with test results of similar-sized beams with fibers
of the estimated first-peak strength, is recommended. A recommended shorter than one-third the width and depth because of preferential fiber
deflection scale is to use 25 mm (1 in.) to represent about 10 % of the alignment, and different size beams may not be comparable because of
end-point deflection of ⁄150 of the span, which is 2 mm (0.08 in.) for a 350 size effects. The degree of preferential fiber alignment may be less for
by 100 by 100 mm (14 by 4 by 4 in.) specimen size, and 3 mm (0.12 in.) fibers that are flexible enough to be bent by contact with aggregate
for a 500 by 150 by 150 mm (20 by 6 by 6 in.) specimen size. When data particles or mold surfaces than for rigid fibers that remain straight during
are digitally stored, the test parameters may be determined directly from mixing and specimen preparation.
FIG. 1 Arrangement to Obtain Net Deflection by Using Two Transducers Mounted on Rectangular Jig Clamped to Specimen Directly
Above Supports
...