apparent reason for this problem as ice was not
Results and discussion
forming on the bottom of the trowels despite the
New Hampshire
cold weather. The high slump, as discussed later,
Test site. At CRREL, a composting bin consist-
may have contributed to this finishing problem.
ing of a 16.5-cm- (6.5 in.) thick reinforced slab on
The EY-11 was placed in the west wall and in the
grade 3.7 m wide by 4.6 m long (12 15 ft) with
west third of the south wall, so finishing charac-
1.2-m- (4 ft) high reinforced 203-mm- (8 in.) thick
teristics could not be evaluated for this admix-
walls on three sides was cast during 17 and 18
ture.
February. The bin was oriented such that the long
Table 23 gives the proportions of the two con-
axis of the slab ran eastwest, and the three walls
crete mixtures used in this study. Table 24 gives
formed the east, south, and west sides of the bin.
the properties of fresh concrete. As previously
The north wall was omitted. The bin was divided
described, Pozzutec 20 was used in the slab and
into five sections, three wall sections and two slab
EY-11 in the wall. The 4% dosage of Pozzutec 20
sections. Dividing the bin in this manner allowed
is equivalent to 60 mL/kg (90 fl oz/cwt) used
for five admixtures to be evaluated. This report
elsewhere in this report. Likewise, the 6% EY-11
discusses the two admixtures provided by Mas-
equates to 95 mL/kg (145 fl oz/cwt).
ter Builders: Pozzutec 20 and EY-11.
The target water-to-cement ratio was 0.44 with
Site preparation consisted of removing a meter
a slump of 100 mm (4 in.). The Pozzutec 20 and
of snow from the ground, placing about 100 mm
EY-11 mixes differed from this target, especially
(4 in.) of dry sand on the newly exposed frozen
in w/c. The water content of the Pozzutec 20 mix
ground, and setting the forms and reinforcing
was intentionally reduced below the target value
steel on the sand. The concrete was placed in the
at the mix plant because Pozzutec 20 contains a
forms, consolidated, and finished as usual. A plas-
high-range water reducer and the mix plant nor-
tic sheet was placed over the slab and over the
mally adds a plasticizer to this mixture. The 0.39
top of the wall for three days to minimize water
w/c resulted in a relatively high slump of 210
loss. The wooden forms were removed from the
mm (8.25 in.) (Table 24). Based on this result, and
walls 20 hours after the concrete was placed. No
because EY-11 also contained a high-range water
thermal protection was provided to the concrete.
reducer, the water content of the EY-11 mixture
Plastic pullout cylinders, 100 150 mm (4 6 in.),
was held to 0.40 at the mix plant. Also, the mix
were cast into the slab and the top of the wall to
plant was requested not to add plasticizer. The
provide in-situ strength gain results. No control
EY-11 concrete unexpectedly arrived at the site
concrete was cast at the site during this study.
with no measurable slump. Thus, water was care-
Workability/finishability. The initial slump of the
fully added to the mix until the concrete in the
EY-11 mix as delivered to the site was poor. The
truck was noticeably looser. The extra water pro-
original concern was that the 6% dosage (Table
duced slump of 127 mm (5 in.) (Table 24) and a
23) of EY-11 was causing the cement to set up too
0.55 w/c (Table 23). The resulting mix was easy to
rapidly but, as explained later, a low water and
place and consolidate within the wall forms. Note
plasticizer content contributed to this low slump.
that the concrete temperatures of both placements
The Pozzutec 20 mix used for the west half of the
were above freezing, not the more desirable be-
slab had good workability, although the concrete
low freezing.
workers complained that the concrete seemed to
Thermal record. Five thermocouples were
tear when finished with a trowel. There was no
equally positioned through the thickness of the
Table 23. Mixture proportions.
Air
Admixture dosage
Rock 3/4-in.
entraining
Water reducer
(wgt active
crushed ledge,
Sand natural
Cement
agent
added at mix plant ingredient per
Mix
0.5% abs 2.89 SG 1.1% abs 2.71 SG
Type II portland
w/c
(Microair)
(WRDA w/Hycol)
cement wgt)
kg/m (lb/yd3) 3
kg/m3 (lb/yd3)
kg/m (lb/yd3) 3
mL/m3 (fl oz/yd3)
mL/m3 (fl oz/yd3)
no.
ratio
(%)
P20
1012
788
421
0.39
798
769
4
(1700)
(1323)
(707)
(27)
(26)
EY-11
1027
777
420
0.55
325
none
6
(1725)
(1305)
(705)
(11)
18
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