Table 30. Test results from 92- 133-mm (4 5.25 in.)
work with the prototype admixture at near-
core samples drilled in July 1994. Densities are based
freezing conditions.
on cylinder dimensions and mass. Minimum design
The northern Michigan field demonstration
strength was 32 MPa (4640 psi).
provided a good evaluation of EY-11 under se-
vere conditions. Normal unprotected concrete
Compressive strength
Bulk density
Evidence of
would have frozen during this test. The freez-
kg/m3 (lb/ft3)
Mix
MPa (psi)
past ice?
ing point depression and accelerated cure prop-
Control
46.7 (6770)
2310 (143.7))
No
erties of the EY-11 concrete enabled it to resist
EY11L
50.6 (7350)
2320 (144.4)
No
freezing.
EY11H
53.2 (7720)
2290 (142.5)
No
The best evidence that the concrete did not
Pozzutec 20
54.1 (7840)
2340 (145.6)
No
freeze was obtained by examining drilled cores.
The core samples taken from each slab four
veloped only about half their potential strength,
months after construction and examined under a
which is indicative of concrete that has frozen
microscope showed no signs of frost damage.
while curing.
The drilled cores were also tested for compres-
Likewise, the strengths of the cylinders stored
sive strength, thereby providing additional infor-
on an overhead shelf in the heated shelter were
mation that the admixtures produced a concrete
not considered useful information other than to
that was unaffected by the outdoor winter condi-
confirm that the admixtures promoted strength
tions.
in concrete cured at above-freezing temperatures.
Other than the cold weather, the major concern
They shed little light on the in-place strength of
during the test was that concrete was placed on a
subgrade that was significantly below the 5C
the concrete slabs.
The most interesting and useful results came
protection capability of the admixtures at their
from cores drilled from each slab in the summer
highest dosage, let alone at the low dosage. The
(Table 30). The cores showed that the antifreeze
concern was that the bottom of the concrete would
concrete was stronger than the control concrete in
be damaged by frost. Gavrish et al. (1974) re-
compression. None of the slabs showed signs of
ported that up to 16 times more heat is lost from a
frost damage.
concrete slab to frozen ground than is lost to the
Cost comparison between conventional and anti-
air during initial curing. From our data, however,
freeze concrete. As previously mentioned, a heated
it was clear that the bottom of the concrete was
shelter was used for the control concrete. This
free from frost damage. The lowest slab-bottom
provided an opportunity to compare costs be-
temperature of the low-dosage EY-11 concrete 21
hours after placement was about 1.2C (30F),
tween normal winter concreting and concreting
with antifreeze admixtures. Based on these field
and for the high-dosage EY-11 concrete four days
after placement, it was 2.6C (27.3F ). At these
tests it became apparent that the main difference
between normal concrete and antifreeze concrete
is the heat, shelter, and labor needed to protect
normal concrete compared to the chemicals
Table 31. Winter cost estimate.
needed to protect antifreeze concrete. The cost to
erect, heat, and dismantle the temporary shelter
Shelter
at the Soo Locks was estimated to be
||content||
,079.54
Erect shelter
(Table 31). Heating accounted for close to 15 per-
(6 men, 1/2 day @ /hr)
2.00
cent of this expense. Since antifreeze admixtures
Heat shelter - 1 d prior to pour and 7 d after
are still prototypes, their market price has not
(8 d @ 21.4 gal propane/d @
||content||
.78/gal)3.54
Dismantle shelter
6.00
been determined. However, based on the esti-
Materials--assume 9 reuses
mate developed for the shelter, the cost of an
(Total cost estimated at
||content||
,062)
8.00
antifreeze could potentially be as high as per
Total estimated cost of shelter
||content||
,079.54
gallon.
Antifreeze admixture
Summary of both field tests. The New Hampshire
field demonstration was not considered to be a
6.7 yd3
Volume of concrete placed inside shelter
severe enough test of the low-temperature capa-
Dosage of admixture per 100 lb of cement
150 fl oz
Amount of cement per yd3 of concrete
658 lbs
bility of EY-11. The concrete did not freeze until it
Amount of admixture per 6.7 yd3 of concrete
51.67 gal
had gained considerable strength. However, this
Cost of admixture to equal cost of shelter
20.89/gal
test showed that no special skills are needed to
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