ASTM A981-97(2002)
(Test Method)Standard Test Method for Evaluating Bond Strength for 15.2 mm (0.6 in.) Diameter Prestressing Steel Strand, Grade 270, Uncoated, Used in Prestressed Ground Anchors
Standard Test Method for Evaluating Bond Strength for 15.2 mm (0.6 in.) Diameter Prestressing Steel Strand, Grade 270, Uncoated, Used in Prestressed Ground Anchors
SCOPE
1.1 This test method describes procedures to establish the relative bond strength of 15.2 mm (0.6 in.) diameter, Grade 270 prestressing steel strand in cement grout as used in prestressed ground anchors for the purpose of evaluating the effects of manufacturing practices on bond strength.
1.2 The bond strength values obtained shall not be used to design the bond length of ground anchors that depend on field conditions.
1.3 This test method is not intended to be used as a bond test for pretensioned concrete applications.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.5 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:A981–97 (Reapproved 2002)
Standard Test Method for
Evaluating Bond Strength for 15.2 mm (0.6 in.) Diameter
Prestressing Steel Strand, Grade 270, Uncoated, Used in
Prestressed Ground Anchors
This standard is issued under the fixed designation A 981; 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. Terminology
1.1 This test method describes procedures to establish the 3.1 Definitions of Terms Specific to This Standard:
relativebondstrengthof15.2mm(0.6in.)diameter,Grade270 3.1.1 bond strength—maximum measured load in a pull test
prestressing steel strand in cement grout as used in prestressed on a 15.2 mm (0.6 in.) diameter prestressing steel strand
ground anchors for the purpose of evaluating the effects of embedded in cement grout.
manufacturing practices on bond strength. 3.1.2 bonded length—the length of the test strand that is in
1.2 The bond strength values obtained shall not be used to contact with the cement grout.
design the bond length of ground anchors that depend on field
4. Apparatus
conditions.
1.3 Thistestmethodisnotintendedtobeusedasabondtest 4.1 Equipment—A suitable tensile test machine or load
frame shall be used. The loading system shall be calibrated in
for pretensioned concrete applications.
1.4 The values stated in SI units are to be regarded as the accordance with Practices E 4. The test system shall have
sufficient capacity to prevent yielding of its various compo-
standard. The values given in parentheses are for information
only. nents and shall ensure that the applied tensile load remains
parallel to the axis of the prestressing steel strand during
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the testing.
4.2 Strand Displacement Measurements—Displacements of
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- the free end of the prestressing steel strand shall be measured
bility of regulatory limitations prior to use. with respect to the loaded surface of the test specimen using
suitable measurement devices. Dial gages having the smallest
2. Referenced Documents
division of not more than 25 µm (0.001 in.) or linear variable
2.1 ASTM Standards: differential transformers (LVDTs) with equal or superior accu-
A 416 Specification for Steel Strand, Uncoated Seven Wire racy are examples of satisfactory devices.
for Prestressed Concrete
3 5. Test Specimen
C 150 Specifications for Portland Cement
C 511 Specification for Moist Cabinets, Moist Rooms and 5.1 Prestressing Steel Strand—shall be 15.2 mm (0.6 in.)
diameter, Grade 270 and comply with SpecificationA 416 and
Water Storage Tanks Used in the Testing of Hydraulic
Cements and Concrete shall be cut from standard production coils. The surface of the
test samples shall not be wiped or cleaned in order to preserve
C 1019 Test Method for Sampling and Testing Grouts
E 4 Practices for Force Verification of Testing Machines their original condition. Minimum recommended sample
length is 750 mm (30 in.).
5.2 Strand Bond Test Specimen—The test specimen shall
consist of the prestressing steel strand embedded in cement
This test method is under the jurisdiction of ASTM Committee A01 on Steel,
groutandcenteredinsideasteelpipe,125mm(5in.)O.D.with
Stainless Steel, and RelatedAlloys and is the direct responsibility of Subcommittee
a 3 mm (0.125 in.) wall, 450 mm (18 in.) long with a 150 by
A01.05 on Steel Reinforcement.
Current edition approved Nov. 10, 1997. Published September 1998.
150 by 6 mm (6 by 6 by 0.25 in.) base plate welded, or
Annual Book of ASTM Standards, Vol 01.04.
otherwise leakproof connected to one end of the steel pipe.
Annual Book of ASTM Standards, Vol 04.02.
Other mold designs, including reusable molds, shall be per-
Annual Book of ASTM Standards, Vol 04.05.
Annual Book of ASTM Standards, Vol 03.01. missible, provided that the dimensions and confinement in
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A981–97 (2002)
regard to circumferential stress provided for the grout body are 5.4 Test Specimen Conditioning—The test specimen includ-
the same.Ahole in the base plate shall allow the strand to pass ing the grout test cubes, shall be cured according to Specifi-
through. A 50 mm (2 in.) long debonding tube shall be cation C 511 at a 23 6 1.7°C (74 6 3°F) temperature and
positioned on the strand above the base plate and the strand minimum 95 percent relative humidity until the grout strength,
shall protrude at least 50 6 10 mm (2 6 0.5 in.) from the top as determined according toTest Method C 1019 on at least two
of the grouted steel tube. A typical test specimen is illustrated 50 by 50 by 50 mm (2 by 2 by 2 in.) test cubes, has reached a
in
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