Table 2. The four phases of work.
Table 3. Phase I tasks.
Phase
Description
Task
Description
I
Evaluation of Pozzutec 20
1
Strength vs. temperature
II
Development of improved admixture
2
Corrosion potential
III
Evaluation of improved admixture
3
Durability
IV
Field application
4
Equivalent insulation
5
Critical strength
had bulk specific gravities of 2.89 and 2.67 and an
Task 1: Strength vs. temperature
absorption of 0.5 and 1.1 percent, respectively.
The objective of this task was to develop a
The coarse aggregate was crushed ledge with a
relationship between the strength gain of con-
gradation that fit between ASTM sizes no. 6 and
crete and its curing temperature. The test proce-
7. The fine aggregate was a natural sand with a
dure consisted of mixing and casting the concrete
fineness modulus of 2.80. The coarse and fine
at room temperature. A few minutes after cast-
aggregate used by MB had specific gravities of
ing, the cylinders were placed into one of several
2.84 and 2.58, respectively. The coarse aggregate
curing rooms set at prescribed temperatures. Con-
was a Drummond Island limestone while the fine
crete temperatures in each of the rooms were
aggregate was a Hugo sand. Tap water was used
monitored for the first seven days by thermo-
for the mix water at each lab.
couples cast into dummy cylinders. A data logger
recorded the temperatures in each dummy cylin-
Scope
der as well as the ambient temperature. All cylin-
A series of laboratory and field tests was con-
ders were sealed to prevent evaporation from the
ducted to evaluate the effect of various chemicals
concrete. At various ages, sets of three cylinders
on properties of concrete. Master Builders devel-
were removed from the curing rooms, allowed to
warm up to 10C (50F), if necessary, and tested
oped chemical formulations for testing and con-
ducted the laboratory studies aimed at defining
for unconfined compressive strength according
strength and chemical reactions of the formula-
to ASTM C 39.
tions. CRREL conducted the low-temperature
The concrete was prepared according to ACI
laboratory and field studies to verify expected
211.1 standards. Fourteen mixes, each with a vol-
ume of 0.057 m3 (2.0 ft3) were batched, twelve
performance of the admixtures.
This project consisted of four phases of experi-
corresponding to three cement factors and four
mental work (Table 2). Phase I involved a com-
admixture dosages for Type I cement, and two
prehensive laboratory testing of Pozzutec 20.
for one cement factor with Type III cement and
Phase II conducted a laboratory screening of nu-
two dosages of admixture (Table 4). Sixty-five
cylinders (75 150 mm [3 6 in.]) were cast per
merous potentially new freezing protection ad-
mix (4 ages 5 temperatures 3 replicate speci-
mixtures, selecting the best for further testing and
evaluation. Phase III used a series of tests similar
mens + 5 dummies).
to those performed on Pozzutec 20 in Phase I on
Each cylinder was identified by three numbers
the best admixture developed in Phase II. Phase
(Table 5): cement factor, admixture dosage, and
IV consisted of two cold weather field trials.
curing temperature. For example, mix (2,0,5) con-
tained the cement factor 2 (365 kg/m3 [611 lb/
yd3]) and no admixture cured at 5C. The mix-
PHASE I: EVALUATION
tures containing Type III cement were identified
OF POZZUTEC 20
by an asterisk (*) preceding the three-digit label.
This scheme is used throughout this report.
Procedure
Once cast, the cylinders were placed into 20, 5,
5, 10, and 20C (70, 40, 23, 14, 4F) rooms
The objective of Phase I was to characterize the
low-temperature performance of Pozzutec 20 and,
within 3045 min of addition of the mix water.
in the process, establish a test protocol for Phase
This ensured that essentially no strength gain took
III. Phase I was divided into five experimental
place at anything but the appropriate curing tem-
tasks (Table 3).
perature. The cylinders remained in each room
3
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