ambient temperature hourly during placing operations, weather
conditions, time of placement, volume yardage placed, and method of
placement.
b. Placing Corrective Action - The placing foreman shall not permit
placing to begin until he has verified that an adequate number of
vibrators in working order and with competent operators are available.
Placing shall not be continued if any pile of concrete is inadequately
consolidated. If any batch of concrete fails to meet the temperature
requirements, immediate steps shall be taken to improve temperature
controls.
3.8.2.9
Vibrators
a. Vibrator Testing and Use - The frequency and amplitude of each
vibrator shall be determined in accordance with COE CRD-C 521prior to
initial use and at least once a month when concrete is being placed.
Additional tests shall be made as directed when a vibrator does not
appear to be adequately consolidating the concrete. The frequency
shall be determined while the vibrator is operating in concrete with
the tachometer being held against the upper end of the vibrator head
while almost submerged and just before the vibrator is withdrawn from
the concrete. The amplitude shall be determined with the head
vibrating in air. Two measurements shall be taken, one near the tip
and another near the upper end of the vibrator head, and these results
averaged. The make, model, type, and size of the vibrator and
frequency and amplitude results shall be reported in writing.
b. Vibrator Corrective Action - Any vibrator not meeting the
requirements of paragraph PREPARATION FOR PLACING shall be immediately
removed from service and repaired or replaced.
3.8.2.10
Curing
a. Moist Curing Inspections - At least twice each shift, and twice per
day on nonwork days an inspection shall be made of all areas subject to
moist curing. The surface moisture condition shall be noted and
recorded.
b. Moist Curing Corrective Action - When a daily inspection report
lists an area of inadequate moistness, immediate corrective action
shall be taken, and the required curing period for those areas shall be
extended by one (1) day.
c. Membrane Curing Inspection - No curing compound shall be applied
until the Contractor's authorized representative has verified that the
compound is properly mixed and ready for spraying. At the end of each
operation, he shall estimate the quantity of compound used by
measurement of the container and the area of concrete surface covered
and compute the rate of coverage in square meters/L square feet per
gallon. He shall note whether or not coverage is uniform.
d. Membrane Curing Corrective Action - When the coverage rate of the
curing compound is less than that specified or when the coverage is not
uniform, the entire surface shall be sprayed again.
e. Sheet Curing Inspection - At least once each shift and once per day
on nonwork days, an inspection shall be made of all areas being cured
using sheets. The condition of the covering and the tightness of the
SECTION 03700
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