ASTM A 416/A 416M, Grade [250] [270], strand diameter as shown. Strand
assemblies may be either shop or field assembled with anchor fittings
positively attached to strands.
2.1.1.2
Stress-Relieved Wire and Wire Assemblies
Stress-relieved wire and wire assemblies shall conform to ASTM A 421/A 421M,
Type BA or WA, wire diameter as shown. Wire assemblies shall be shop
assembled with anchor fittings positively attached to wires.
2.1.1.3
High-Strength Steel Bars
High-strength steel bars shall conform to ASTM A 722/A 722M, Type I or II,
meeting all supplementary requirements.
2.1.2
Accessories
2.1.2.1
Ducts
Tendon ducts shall be of ferrous metal, capable of transmitting forces from
grout to the surrounding concrete, flexible enough to conform to the tendon
profile and strong enough to maintain their shape without deforming,
sagging, or collapsing during concrete placement and vibration. The inside
diameter of the ducts shall be large enough to provide an internal area at
least twice the gross area of multiple wire, bar or strand assemblies and
shall be at least 6 mm 1/4-inch larger than the diameter of a single wire,
bar or strand placed in the ducts. Ducts shall be designed for watertight
connections with all fittings. Galvanized ducts will not be permitted.
2.1.2.2
Anchorages and Couplers
Anchorages and couplers shall be metal of proven corrosion resistance and
compatible with the stressing tendons, capable of fully developing the
minimum guaranteed ultimate strength of tendons without excessive slip and
approved. Anchorages shall be the button-head, wedge, nut and thread, grip
nut, thread-bar, threaded plate or other approved type and shall be
provided with bearing plates bars, rings, bells or other positive-attaching
anchor fittings. Couplers shall be provided with housings long enough to
permit the necessary movements and fittings which allow complete grouting
of all components.
2.1.2.3
Grout
Grout for grouting post-tensioned tendons shall consist of a mixture of
Portland cement, shrinkage compensating admixture and potable water of
which final proportions shall be based on test results of sample mixtures.
Cement shall conform to ASTM C 150, Type I or II. The shrinkage
compensating admixture shall produce a 2 percent minimum and a 10 percent
maximum unconfined expansion when tested in accordance with ASTM C 940,
shall not contain aluminum powder, chlorides, fluorides or nitrates, may be
dispensed in solid or liquid form and must be approved by the Contracting
Officer prior to its use. The water content shall be the minimum necessary
for proper placement but the water-cement ratio shall not exceed 0.50 by
weight. The pumpability of grout shall be determined in accordance with
ASTM C 939. The efflux time of a grout sample immediately after mixing
shall not be less than 11 seconds. The minimum 7-day compressive strength
of 50 mm 2-inch grout cubes, molded, cured and tested in accordance with
ASTM C 109/C 109M shall be 17.2 MPa. 2500 psi.
SECTION 03230
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