ASTM A944-99(2004)
(Test Method)Standard Test Method for Comparing Bond Strength of Steel Reinforcing Bars to Concrete Using Beam-End Specimens
Standard Test Method for Comparing Bond Strength of Steel Reinforcing Bars to Concrete Using Beam-End Specimens
SCOPE
1.1 This test method describes procedures to establish the relative bond strength of steel reinforcing bars in concrete.
1.2 This test method is intended to determine the effects of surface preparation or condition (such as bar coatings) on the bond strength of deformed steel reinforcing bars (of sizes ranging from No. 10 to No. 36 [No. 3 to No. 11]) to concrete.
1.3 The values stated in SI units are to be regarded as the standard. The values given in brackets are for information only.
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.
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Designation:A 944–99 (Reapproved 2004)
Standard Test Method for
Comparing Bond Strength of Steel Reinforcing Bars to
Concrete Using Beam-End Specimens
This standard is issued under the fixed designation A 944; 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 3.1.4 embedment length, n—thedistancefromthesurfaceof
the concrete test specimen to the installed end of the steel
1.1 This test method describes procedures to establish the
reinforcing bar. This equals the sum of the lead length and the
relative bond strength of steel reinforcing bars in concrete.
bonded length.
1.2 This test method is intended to determine the effects of
3.1.5 lead length, n—the length of the test bar that is not in
surface preparation or condition (such as bar coatings) on the
contact with concrete but is between the surface of the concrete
bond strength of deformed steel reinforcing bars (of sizes
test specimen and the bonded length.
ranging from No. 10 to No. 36 [No. 3 to No. 11]) to concrete.
3.1.6 relative rib area, n—ratio of the projected rib area
1.3 The values stated in SI units are to be regarded as the
normal to bar axis to the product of the nominal bar perimeter
standard.Thevaluesgiveninbracketsareforinformationonly.
and the center-to-center rib spacing.
1.4 This standard does not purport to address all of the
3.2 Symbols:
safety concerns, if any, associated with its use. It is the
C = Concrete cover, mm [in.].
b
responsibility of the user of this standard to establish appro-
d = Nominal diameter of reinforcing bar, mm [in.].
b
priate safety and health practices and determine the applica-
l = Embedment length, mm [in.].
e
bility of regulatory limitations prior to use.
4. Apparatus
2. Referenced Documents
4.1 Equipment—A schematic of a suitable testing system is
2.1 ASTM Standards:
shown in Fig. 1. The loading system shall be capable of
C 192/C 192M Practice for Making and Curing Concrete
measuring the forces to an accuracy within 62 % of the
Test Specimens in the Laboratory
applied load, when calibrated in accordance with Practices E 4.
E 4 Practices for Force Verification of Testing Machines
The test system shall have sufficient capacity to prevent
E 575 Practice for Reporting Data from Structural Tests of
yielding of its various components and shall ensure that the
Building Constructions, Elements, Connections, and As-
applied tensile load remains parallel to the axis of the steel
semblies
reinforcing bar during testing.
3. Terminology
4.2 Compression Reaction Plate—The compression reac-
tionplateshallbeplacedaminimumcleardistanceequalto0.9
3.1 Definitions of Terms Specific to This Standard:
l measured from the center of the test bar to the edge of the
3.1.1 bond strength, n—maximum measured load in a e
reaction plate.
tensile bond test of a steel reinforcing bar.
4.3 Bar Displacement Measurements—Displacements of
3.1.2 bonded length, n—the length of the test bar that is in
the loaded and free ends of the steel reinforcing bar shall be
contact with concrete.
measured with respect to the loaded and free surfaces, respec-
3.1.3 concrete cover, n—minimum distance between the
tively, of the concrete using suitable measurement devices.
surface of the test bar and the top or bottom of the test
Dial gages having the smallest division of not more than 25 µm
specimen.
[0.001 in.] or linear variable differential transformers (LVDTs)
with equal or superior accuracy are examples of satisfactory
This test method is under the jurisdiction of ASTM Committee A01 on Steel,
devices.
Stainless Steel, and RelatedAlloys and is the direct responsibility of Subcommittee
A01.05 on Steel Reinforcement.
5. Test Specimen
Current edition approved Nov. 10, 1999. Published January 2000. Originally
approved in 1995. Last previous edition approved in 1999 as A 944 – 99. 5.1 Beam-End Specimen—The test specimen shall consist
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
of the test bar cast in a block of reinforced concrete 600 6 25
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
mm [24 6 1 in.] long by d + 200 6 13 mm [d+8 6 ⁄2 in.]
b b
Standards volume information, refer to the standard’s Document Summary page on
wide by a minimum of d+C+l+60mm[d+C+l+2 ⁄2
the ASTM website.
b b e b b e
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
A 944–99 (2004)
FIG. 1 Schematic of Test Apparatus
NOTE 1—The lead length, shown in Fig. 2, is typically between 13 and
in.] high. A typical test specimen is illustrated in Fig. 2. The
100 mm [0.5 and 4 in.]. This unbonded region is used to prevent a
specimen shall be reinforced by four closed stirrups oriented
cone-type pullout failure at the surface of the concrete. Increases in lead
parallel to the sides of the specimen and two flexural steel
length generally result in an increase in bond strength.
reinforcing bars parallel to the test bar, as shown in Fig. 2.
Transverse steel reinforcing bars similar to those illustrated in 5.2 Fabrication—The concrete block shall be fabricated
usingconcretedesignedtoproduceastrengthatthetimeoftest
Fig.2maybeusedtoaidinfabricationandtesting.Thetestbar
shall extend from the front surface a distance that is compatible between 31 and 38 MPa [4500 and 5500 psi]. The specimen
shall be cast in
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