ASTM C1399-00

Test Method for Obtaining Average Residual-Strength of Fiber-Reinforced Concrete

SCOPE
1.1 This test method covers the determination of residual strength of a fiber-reinforced concrete test beam. The average residual strength is computed for specified beam deflections beginning after the beam has been cracked in a standard manner. The test provides data needed to obtain that portion of the load-deflection curve beyond which significant cracking damage has occurred and it provides a measure of post-cracking strength, as such strength is affected by the use of fiber-reinforcement.
1.2 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.
1.3 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.

General Information

• Status: Historical
• Publication Date: 09-Nov-2001
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.42 - Fiber-Reinforced Concrete

Relations

• Replaced By: ASTM C1399-01 - Test Method for Obtaining Average Residual-Strength of Fiber-Reinforced Concrete
• Effective Date: 10-Nov-2001

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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.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 1399 – 00
Test Method for
Obtaining Average Residual-Strength of Fiber-Reinforced
Concrete
This standard is issued under the fixed designation C 1399; 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 tained in a manner that excludes deflection caused by the
following: (1) the flexural test apparatus, (2) crushing and
1.1 This test method covers the determination of residual
seating of the beam at support contact points, and (3) torsion of
strength of a fiber–reinforced concrete test beam. The average
the beam; sometimes termed net deflection.
residual strength is computed for specified beam deflections
3.1.2 initial loading curve—the load–deflection curve ob-
beginning after the beam has been cracked in a standard
tained by testing an assembly that includes both the test beam
manner. The test provides data needed to obtain that portion of
and a specified steel plate (Fig. 1); plotted to a deflection of at
the load–deflection curve beyond which significant cracking
least 0.25 mm (0.010 in.) (Fig. 2).
damage has occurred and it provides a measure of post–crack-
3.1.3 reloading curve—the load–deflection curve obtained
ing strength, as such strength is affected by the use of
by reloading and retesting the precracked beam, that is, after
fiber–reinforcement.
the initial loading but without the steel plate. (Fig. 2)
1.2 This standard does not purport to address all of the
3.1.4 reloading deflection—deflection measured during the
safety concerns, if any, associated with its use. It is the
reloading of the cracked beam and with zero deflection
responsibility of the user of this standard to establish appro-
referenced to the start of the reloading.
priate safety and health practices and determine the applica-
3.1.5 residual strength—the flexural stress on the cracked
bility of regulatory limitations prior to use.
beam section obtained by calculation using loads obtained
1.3 The values stated in SI units are to be regarded as the
from the reloading curve at specified deflection values (see
standard. The values in parentheses are for information only.
Note 1).
2. Referenced Documents
NOTE 1—Residual strength is not a true stress but an engineering stress
2.1 ASTM Standards:
computed using the flexure formula for linear elastic materials and gross
C 31 Practice for Making and Curing Concrete Test Speci- (uncracked) section properties.
mens in the Field
3.1.6 average residual strength—the average stress–carry-
C 42 Test Method for Obtaining and Testing Drilled Cores
ing ability of the cracked beam that is obtained by calculation
and Sawed Beams of Concrete
using the residual strength at four specified deflections.
C 78 Test Method for Flexural Strength of Concrete (Using
4. Summary of Test Method
Simple Beam with Third–Point Loading)
C 172 Practice for Sampling Freshly Mixed Concrete
4.1 Cast or sawed beams of fiber–reinforced concrete are
C 192 Practice for Making and Curing Concrete Test Speci-
cracked using the third–point loading apparatus specified in
mens in the Laboratory
Test Method C 78 modified by a steel plate used to assist in
C 823 Practice for Examining and Sampling of Hardened
support of the concrete beam during an initial loading cycle
Concrete in Constructions
(Fig. 1). The steel plate is used to help control the rate of
C 1018 Test Method for Flexural Toughness and First Crack
deflection when the beam cracks. After the beam has been
Strength of Fiber-Reinforced Concrete (Using Beam With
cracked in the specified manner, the steel plate is removed and
Third Point Loading)
the cracked beam is reloaded to obtain data to plot a reloading
load–deflection curve. Load values at specified deflection
3. Terminology
values on the reloading curve are averaged and used to
3.1 Definitions of Terms Specific to This Standard:
calculate the average residual strength of the beam.
3.1.1 deflection—mid–span deflection of the test beam ob-
5. Significance and Use
5.1 This test method provides a quantitative measure useful
This specification is under the jurisdiction of ASTM Committee C09 on
Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee in the evaluation of the performance of fiber–reinforced
C09.42 on Fiber-Reinforced Concrete.
concrete. It allows for comparative analysis among beams
Current edition approved June 10, 2000. Published August 2000. Originally
containing different fiber types, including materials, dimension
published as C 1399–98. Last previous edition C 1399–98.
and shape, and different fiber contents. Results can be used to
Annual Book of ASTM Standards, Vol 04.02.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
C 1399
FIG. 1 Diagrammatic View of a Suitable Apparatus for Residual Strength Test of Fiber-Reinforced Concrete
optimize the proportions of fiber–reinforced concrete mixtures, the ability to control the rate of motion of the loading head and
to determine compliance with construction specifications, to meeting the requirements of Test Method C 78. A load cell with
evaluate fiber–reinforced concrete which has been in service, a 44.5 kN capacity (10,000 lbf) will generally be required.
and as a tool for research and development of fiber–reinforced Closed–loop feed–back controlled deflection apparatus is not
concrete (see Note 2). required.
6.2 Flexural–Loading Beam–Support Apparatus, conform-
NOTE 2—Banthia and Dubey compared results using this test method
ing to the requirements of Test Method C 78.
with residual strengths at the same net deflections from Test Method
6.3 Load and Deflection–Measuring Devices, such as load
C 1018 on 45 beams with a single fiber configuration at proportions of 0.1,
0.3, and 0.5 % by volume and reported an average 6.4 % lower than Test cells and electronic transducers, capable of producing elec-
Method C 1018 test results.
tronic analog signals and having support apparatus located and
arranged in a manner that provide determination of applied
5.2 Test results are intended to reflect either consistency or
load and mid-span deflection (see 3.1.5) of the beam. Measure
differences among variables used in proportioning the fiber-
deflection using a device capable of measuring net deflection at
–reinforced concrete to be tested, including fiber type (mate-
the beam mid–span with a minimum resolution of 0.025 mm
rial), fiber size and shape, fiber amount, beam preparation
(0.001 in.) by one of the following alternative methods (see
(sawed or molded), and beam conditioning.
Note 3).
5.3 In molded beams fiber orientation near molded surfaces
will be affected by the process of molding. For tests of
NOTE 3—The deflection measurement requires care in the arrangement
fiber–reinforced concrete containing relatively rigid or stiff
of displacement transducers in order to minimize extraneous contributions
such as might be caused by seating or twisting of the specimen. A
fibers of length greater than 40 mm (1.5 in.), use of sawed
suggested method to accomplish this measurement uses a spring–loaded
beams cut from samples which had initially a width and depth
electronic displacement transducer mounted on a suspension yoke as is
at least 3 times the length of the fiber is recommended to
shown in Fig. 1.
minimize effects of fiber orientation.
6.3.1 Three Electronic Transducers, mounted on a support
6. Apparatus
frame. The support frame positions the transducers along the
centerline of the top surface of the test beam at locations so as
6.1 Either Screw Gear or Hydraulic Testing Apparatus, with
to contact the beam at midspan and each support location.
Average the measured support deflections and subtract this
Banthia, N. and Dubey, A., “Measurement of Flexural Toughness of Fiber
value from the recorded mid–span deflection to obtain the net
Reinforced Concrete Using a Novel Technique, Part I: Assessment and Calibration,”
In Press, Materials Journal, American Concrete Institute. deflection.
C 1399
FIG. 2 Load-Deflection Curves
6.3.2 Two Electronic Transducers, mounted on a support 6.5 Stainless Steel Plate, nominally 100 by 12 by 350 mm (4
frame. The support frame either (1) surrounds the test beam by ⁄2 by 14 in.) (see Note 4)
and is clamped to the sides of the beam at points on a line
NOTE 4—Depending upon the chosen method for obtaining net deflec-
passing vertically through the b
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