EY-11 concretes were very easy to place,
consolidate, and finish, according to the con-
March `94
30
crete workers. The concrete maintained its
Control
workability throughout the finishing op-
20
eration, which lasted nearly two hours af-
ter water was first added to the mixtures at
10
the mix plant. According to workers' com-
Air
ments, the EY-11 mixture seemed to be
somewhat easier to finish compared to the
0
Pozzutec 20 or the control, though no diffi-
culty was noted with working with any of
10
15
16
17
18
19
20
21
22
23
the mixtures.
Time (days)
Thermal record. Thermocouples connected
Figure 12. Temperature history of the top surface of the con-
to data loggers monitored concrete and air
trol slab and the heated air in the control shelter at Sault Ste.
temperatures. Five thermocouples were
Marie, Michigan.
equally spaced throughout the thickness of
each slab, beginning at the top surface. (The
10
temperature of the Pozzutec 20 was not re-
March `94
corded due to equipment malfunction.) An
5
additional thermocouple was positioned
EY11L
away from the concrete, 150 mm (6 in.)
0
above grade and out of direct sunlight, to
record the ambient air temperature. For this
5
report, only the data from the top surface
Air
thermocouples are provided because the
10
top surface was the coolest portion of each
slab--it cooled quicker and experienced
15
wider temperature excursions than the rest
15
16
17
18
19
20
21
22
23
Time (days)
of the slab, including the bottom surface,
which was in contact with the cold gravel.
Figure 13. Temperature history of the top surface of the EY11L
Figures 1214 show the temperatures of the
slab and that of the outdoor air at Sault Ste. Marie, Michigan.
slabs' top surfaces and the temperature of
surrounding ambient air. The recording
20
period for each concrete section began at
March `94
the time shown in Table 28 and extends
EY11H
10
through midnight, 22 March.
Figure 12 shows the temperatures of the
control concrete and the heated air in the
0
shelter. The shelter was heated for several
days before 15 March to thaw the frozen
ground. To facilitate placement of the con-
10
Air
trol concrete, two walls of the shelter were
removed at 10:30 a.m. on 15 March and
20
replaced at noon. The air inside the shelter
15
16
17
18
19
20
21
22
23
cooled to 6.6C (20F) by the time concret-
Time (days)
Figure 14. Temperature history of the top surface of the EY11H
ing started, but after the walls were re-
slab and that of the outdoor air at Sault Ste. Marie, Michigan.
placed, the shelter warmed up again. How-
ever, the shelter temperature fluctuated
daily. The maximum of 29.7C (85F) occurred at
side the heated shelter. The workers found the
4:10 p.m. on the 16th, and two lows of 0.2C
freedom of movement better outdoors than in a
(31F) and 0.4C (33F) occurred at 3:30 a.m. on
temporary enclosure, while the heated shelter was
useful as a warming hut between concrete deliv-
the 19th and at 6:45 a.m. on the 20th, respectively.
eries. The workers remained outdoors for periods
The two low temperatures were caused by a mal-
of approximately two hours. The Pozzutec 20 and
function of the heating equipment. The heat was
22
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