applied continuously under moderate pressure at the other end until all
entrapped air is forced out as indicated by a uniform flow of grout from
the discharge vent. The discharge vent shall then be closed and the
pressure raised to 340 MPa 50 psi minimum and held for at least 1 minute.
The injection point shall then be closed by an approved means to prevent
any loss of grout. For a period of at least 3 days after grouting the
tendons, the prestressed members shall not have equipment or other loads
placed on them. A longer period may be required, depending upon the method
of curing and magnitude of imposed stresses.
3.1.7
Accuracy of Stress and Elongation Measurement
3.1.7.1
Stress Measurement
Hydraulic gauges, dynamometers, load cells or other devices for measuring
stressing load shall have an accuracy of reading within two percent for
stress measurement. Gauges are required to have been calibrated for the
jacks for which they are used within a period not exceeding 12 months.
Recalibration shall be performed at any time that a gaging system shows
indication of erratic results in the opinion of the Contracting Officer.
Gauges shall indicate loads directly in kilonewtons pounds or be
accompanied by a chart which converts dial readings into kilonewtons pounds.
3.1.7.2
Elongation Measurement
After the initial force has been applied to a tendon, reference points for
measuring elongation due to additional tensioning forces shall be
established. They shall be located according to the method of tensioning
and type of equipment. The system used shall be capable of measuring the
true elongation plus or minus 2 mm. 1/16-inch.
3.1.8
Prestressing Operations Records
The Contractor shall compile and submit complete prestressing operations
records to the Contracting Officer. These records shall show the
manufacturer, identification and description of materials and equipment
including prestressing tendons and jacking and load measuring equipment;
location of prestressing tendons; initial design tensioning loads, final
design tensioning loads and actual tensioning loads for tendons; dates
tensioning loads applied; and theoretical and actual elongations for
tendons.
3.2
INSPECTION
The Contractor's facilities shall be open for inspection by the Contracting
Officer at any time.
3.3
MATERIALS DISPOSITION RECORDS
Accurate materials disposition records identifying all materials
incorporated into the work and showing the disposition of specific lots of
approved tested materials shall be compiled by the Contractor.
-- End of Section --
SECTION 03230
Page 11
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