long by 15 cm thick, to the experiment; they were
cast on 15 through 17 March. Inspection and re-
1.9 cm max.
pair of the locks and other repair work, such as
the replacement of these slabs, is most conve-
niently done during the winter, after the ship-
ping season, making this test particularly rele-
The site was prepared by jackhammering out
*Weight active ingredient per cement weight.
alternate sections of concrete, replacing 15 cm of
base material with coarse gravel, and setting
Table 2. Concrete placement time.
forms and reinforcing steel. The slabs that re-
mained between the removed sections provided
work space for finishing operations. A tempo-
rary, propane-heated enclosure (Fig. 2) was erect-
ed over one slab as a control section (admixture-
free) to provide a comparison between normal
and antifreeze concreting operations. An unheat-
ed enclosure covered one of the admixture sec-
The concrete was transported by rotary-drum
tions as a secondary test. Concrete made with
truck from a ready-mix plant 8 km from the job
admixtures was placed in the two sections ex-
site. The concrete was mixed with unheated ag-
posed to ambient air outside the shelter and in
gregate and heated water. The ingredients, in-
the section in the unheated shelter.
cluding all admixtures, were mixed before being
Figure 2. Temporary heated shelter.
Two admixtures were tested: the EY11 and DP
given in Table 1). Table 2 gives the concrete place-
prototypes. The EY11 admixture was used in two
ment times. The concrete was delivered 30 to 45
dosages: low and high, designated EY11L and
minutes after water was added to the mix, and it
EY11H. The DP admixture was used in a single
was placed within another 30 minutes. Consoli-
dosage. Both DP and EY11H were capable of pro-
dation and finishing operations took another 45
tecting concrete down to 5C. The EY11L was
to 60 minutes. Table 3 gives the properties of the
expected to work down to around 3C.