selection criteria at this stage were chiefly
in Phase 1.
based on the strength developed at seven
days of cure at 5C. In these graphs each
Antifreeze admixture
Dosage
Water/cement
mixture is identified by a code. The first two
Mix no.
formulation
(% CWT)
ratio
characters indicate the task number for which
1A_1*
Control admixture-free
0
0.48
the test results were obtained followed by
1A_20
KC1 (3 parts of sodium nitrate
the mix number used in the corresponding
+ 1 part of sodium sulfate)
8.0
0.48
task. Figures 1a through 1d display the test
1B_19
CCSN
4.0
0.48
results at 20C, 5C, 10C, and 20C. Two
1D_4
K2CO2 + lignosulfonate
6.0/1.5
0.38
1D_7
Ca(NO2)2 + NaNO2
3.0/3.0
0.48
control curves corresponding to admixture-
CM-48†
6.0
0.48
1E_5
free concrete are included for reference. One
CM-42†
1E_3
6.0
0.48
corresponds to concrete cured at 20C. The
Ca(NO2)2 + WRDA-19**
1F_8
4.0/0.7
0.40
second corresponds to concrete cured at 5C,
DP†
6.0
0.43
1H_2
†
the lowest temperature currently covered by
1H_6
DPTC
6.0
0.43
the ACI 306 specification. Table 5 shows the
* 1A_1 means mix number 1 in task 1A.
chemical composition of the selected admix-
† Code name used only to protect proprietary rights.
tures. The admixtures subject to proprietary
** WRDA-19 is a high-range water-reducing admixture commercially
available from W.R. Grace, Inc.
rights are identified by their code name only.
Figure 1a, corresponding to a curing tem-
mens cured at 5C that was equal to or better
perature of 20C, shows that CCSN (Mix No.
than that of nonadmixture concrete cured at 5C.
1B_19) enhanced the strength of concrete for at
The admixtures that developed higher strength at
least the first 28 days. The admixture Ca(NO2)2 +
5C were selected for further testing in Phase 2.
NaNO2 (mix 1D_7) caused lower strength at seven
It is important to note that these temperatures are
days, but higher strength at 14 days and thereaf-
at the center of mass of concrete cylinders. In ac-
ter. The admixture K2CO2 + lignosulfonate (mix
tual concrete structures, the air temperature can
1D_4) reduced the strength at all times, at least up
be significantly lower without harming the con-
to 28 days. The rest of the admixtures did not
crete because of the effect of the internal heat of
have a significant effect at room temperature.
hydration.
Figure 1b, corresponding to a curing tempera-
ture of 5C, shows that most of the selected ad-
Analysis of Phase 1 test results
mixtures allowed concrete strengths to be between
the values for the 20C and 5C control concrete.
The strength performances of the selected ad-
mixtures are presented in the figures below. The
Any strength developed at low temperature that
7000
6000
5000
4000
Control +20C
3000
Control +5C
1A 20
2000
1B 19
1D 4
1D 7
1000
1E 5
1E 3
0
0
7
14
21
28
Concrete Age (days)
a. 20C.
Figure 1. Compressive strength of best admixtures of Phase 1 cured at
various temperatures. Mixes 1F_8, 1H_2, and 1H_6 were not tested at
20C.
4
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