SPECIAL REPORT 97-9

Developing New Low-Temperature

Admixtures for Concrete

A Field Evaluation

Charles Korhonen, Brian Charest, and Kurt Romisch April 1997
Abstract: Two new admixtures, capable of preventing

water from freezing, as well as increasing the hydration rate of cement at below-freezing temperatures,

were field tested at Sault Ste. Marie, Michigan. Concrete made with the admixtures was placed on a frozen subgrade during a cold winter day and was alHow to get copies of CRREL technical publications:

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lowed to cure thermally, unprotected in the cold. Comparison to control concrete placed inside a heated

shelter showed that the unprotected, admixtured concrete was equal to the control in strength and appearance. Work is continuing on the development of these

admixtures for commercial use.
Special Report 97-9

Developing New Low-Temperature

Admixtures for Concrete

A Field Evaluation

Charles Korhonen, Brian Charest, and Kurt Romisch April 1997

Prepared for

OFFICE OF THE CHIEF OF ENGINEERS

Approved for public release; distribution is unlimited.

US Army Corps

of Engineers®

Cold Regions Research &

Engineering Laboratory
PREFACE

This report was prepared by Charles Korhonen, Research Civil Engineer, Brian Charest,

Research Civil Engineer, of the Civil and Geotechnical Engineering Division, Research

and Engineering Directorate, U.S. Army Cold Regions Research and Engineering Laboratory; and Kurt Romisch, Chief, SYM Shops, Yards and Mechanical Branch, Soo Area Office, U.S. Army Engineer District, Detroit. The investigation was conducted under the authority of the Corps Construction Productivity Advance Research (CPAR) program.

The authors acknowledge the support of Stanley Jacek, Area Engineer, Soo Area Office,

as well as of the work crew from the Soo that placed the concrete. Technical review was

provided by William F. Quinn (CRREL) and John W. Brook (Master Builders, Inc., Cleveland, Ohio).

The contents of this report are not to be used for advertising or promotional purposes.

Citation of brand names does not constitute an official endorsement or approval of the use

of such commercial products.

ii
INTRODUCTION

During March 1994, an innovative way of protecting fresh concrete from freezing was field

tested in northern Michigan at the Soo Locks in

Sault Ste. Marie (run by the U.S. Army Engineer

District, Detroit). Instead of using the customary

insulation or heated enclosures, special chemical

compounds were added to the concrete to help it

gain strength while its internal temperature was

below the freezing point of water. Two prototype

chemical formulations, antifreeze admixtures,

were developed as part of the Corps Construction Productivity Advancement Research

(CPAR) program. This field test intentionally allowed fresh concrete to cool below freezing without any attempt being made to insulate or heat it.

BACKGROUND

Construction Productivity Advancement

Research (CPAR) program

CPAR allows Corps research laboratories,

such as CRREL, to work with private industry on

Research and Development that has potential for

advancing the art of construction and for being

of value to Corps activities. The intent of CPAR is

to catalyze improved construction technology

through cooperative, cost-shared ventures. Such

a venture resulted in the development of the two

admixtures described in this report.

These admixtures were developed under two

independent projects—Master Builders, Inc.,

and W.R. Grace & Co. entered into separate contracts with CRREL in 1991. Each project was successful in bringing a practical antifreeze admixture to the threshold of commercialization.

Conventional practice

Current winter concreting practices have remained unchanged for many years. Concrete ingredients must be heated to melt all ice and to

create a mix temperature that is well above freezing; the substrate on which fresh concrete is

placed must be thawed; and the concrete must be

kept warm and moist long enough to assure adequate strength.

Construction standards require that normal

concrete be kept at or above 5°C (ACI 1988) until

it has cured. As temperatures drop to this mark,

finishing operations take longer and forms cannot be stripped as fast as they can during the

summer. The strength gain of concrete is slowed.

At a few degrees below zero, not only is the hydration rate of cement slow, the mix water begins

to turn into ice. At –3°C, 90% of the water will

freeze (Korhonen 1990). If freezing occurs, the

concrete may lose half its strength. Figure 1

shows the effect of temperature on the strength

of normal concrete.

Freezing, however, is a threat for only a short

time. As concrete matures and water chemically

combines with cement, the quantity of freezable

water diminishes to the point that freezing the

concrete once will not damage it. Most concrete

develops this level of self-protection by the time

it reaches a compressive strength of 3.5 MPa

(ACI 1988), which, for normal concrete cured at

10°C, can happen in a day.

The procedures used today to protect concrete

from freezing and to assure adequate strength do

produce concrete that meets construction needs

for strength and durability. However, this protection can be expensive. It has been estimated that

the U.S. construction industry spends $800 milDeveloping New Low-Temperature Admixtures for Concrete

A Field Evaluation

CHARLES KORHONEN, BRIAN CHAREST, AND KURT ROMISCH
lion every year on measures to protect fresh concrete from freezing (Civil Engineering 1991).

Antifreeze admixtures

Antifreeze admixtures are chemicals that

depress the freezing point of water and accelerate the hydration of cement. The literature cites

numerous chemicals that can function as accelerators, calcium chloride being the most popular.

And there are many common substances that

dissolve in water and can serve as freezing point

depressants. The challenge, however, is to find

chemicals that will work together and that will

not harm the concrete.

Because no standards or acceptance criteria

are available for antifreeze admixtures, it was

necessary at the start of the CPAR projects to

define such criteria. An antifreeze admixture

should:

• Depress the freezing point of water.

• Promote strength gain of concrete at low

temperatures.

• Not interfere with concrete strength gain at

normal temperatures.

• Maintain the workability of the concrete.

• Achieve a reasonable concrete set time.

• Produce freeze–thaw durable concrete.

• Not react with silica aggregate.

• Not corrode steel.

• Not adversely alter hydration products.

• Be cost effective.

Also, we decided that the initial low-temperature goal would be –5°C, with –10°C or perhaps

–20°C being the ultimate objective, and that the

concrete cured at this low temperature should

gain strength at least as rapidly as normal concrete cured at 5°C.

Numerous chemical mixtures were investigated before one prototype formulation from each

company was selected for final testing: EY11

from Master Builders, Inc., and DP from W.R.

Grace & Co. Because the admixtures are proprietary, the chemicals used in them are not disclosed.

Data from nearly two years of laboratory testing have not proven that the prototype admixtures harm the concrete. The concrete made with

each admixture passed standard freeze–thaw

tests, did not shrink excessively, did not contain

excess alkalis, and did not promote corrosion.

Further, the admixtures promoted strength in

concrete cured at –5°C that exceeded the strength

attained by normal concrete cured at 5°C. The

prototypes were ready for field evaluation.

FIELD EVALUATION

Soo Locks

The Soo Area Office was replacing 39 sections

of concrete that showed advanced freeze–thaw

deterioration. They devoted four reinforced

slabs on grade, measuring 5.5 m wide by 6.1 m

2

150

125

100

75

50

25

0

0 10 20 30 40 50 60 70 80 90

Days

Relative Strength (%)

–10 ̊C

– 5 ̊C

–20 ̊C

 20 ̊C

 10 ̊C

 5 ̊C

 40 ̊C

20 ̊C Cure

Figure 1. Effect of temperature on strength gain of normal concrete. All

strengths are referenced to the 28-day strength of the 20°C concrete. The 40, 10

and 5°C lines are based on relations presented by ACI. The other data are from

laboratory tests at CRREL.
long by 15 cm thick, to the experiment; they were

cast on 15 through 17 March. Inspection and repair of the locks and other repair work, such as

the replacement of these slabs, is most conveniently done during the winter, after the shipping season, making this test particularly relevant.

Site preparation

The site was prepared by jackhammering out

alternate sections of concrete, replacing 15 cm of

base material with coarse gravel, and setting

forms and reinforcing steel. The slabs that remained between the removed sections provided

work space for finishing operations. A temporary, propane-heated enclosure (Fig. 2) was erected over one slab as a control section (admixturefree) to provide a comparison between normal

and antifreeze concreting operations. An unheated enclosure covered one of the admixture sections as a secondary test. Concrete made with

admixtures was placed in the two sections exposed to ambient air outside the shelter and in

the section in the unheated shelter.

Concrete

Two admixtures were tested: the EY11 and DP

prototypes. The EY11 admixture was used in two

dosages: low and high, designated EY11L and

EY11H. The DP admixture was used in a single

dosage. Both DP and EY11H were capable of protecting concrete down to –5°C. The EY11L was

expected to work down to around –3°C.

The concrete was transported by rotary-drum

truck from a ready-mix plant 8 km from the job

site. The concrete was mixed with unheated aggregate and heated water. The ingredients, including all admixtures, were mixed before being

added into the truck (the mix proportions are

given in Table 1). Table 2 gives the concrete placement times. The concrete was delivered 30 to 45

minutes after water was added to the mix, and it

was placed within another 30 minutes. Consolidation and finishing operations took another 45

to 60 minutes. Table 3 gives the properties of the

fresh concrete.

3

Table 1. Mix proportions.

1.9 cm max. Type 1A

size coarse portland Admixture

aggregate Sand cement W/C dosage*

Mix (kg/m3) (kg/m3) (kg/m3) ratio (%)

Control 1047 774 392 0.41 None

EY11L 1047 774 392 0.41 3.7

EY11H 1047 774 392 0.38 6.3

DP 1047 774 392 0.41 5.2

*Weight active ingredient per cement weight.

Table 2. Concrete placement time.

Mix Date Start

Control 15 Mar 11:00 a.m.

EY11L 16 Mar 9:45 a.m.

EY11H 16 Mar 11:40 a.m.

DP 17 Mar 1:10 p.m.

Figure 2. Temporary heated shelter.
Placing and curing concrete

The concrete for all sections was placed and

finished in the normal fashion. No extra effort or

skill was required to work outdoors compared to

doing the same work inside the heated shelter.

The workers found the freedom of movement

better outdoors than in the temporary enclosure.

The heated shelter was useful as a warming hut

between concrete deliveries. The workers stayed

outdoors for approximately 2-hour periods. Except for the heated control section, the concrete

was thermally unprotected. A plastic sheet was

placed over the two exposed concrete sections

for 7 days to minimize water loss (Fig. 3). The

concrete in the two shelters was uncovered.

Thermal history

Thermocouples connected to data loggers

monitored concrete and air temperatures. Five

thermocouples were equally spaced through the

thickness of each slab, beginning at the top surface. An additional thermocouple was positioned away from the concrete, 15 cm above

grade and out of direct sunlight, to record the air

temperature. For this report only the data from

the top surface thermocouples are provided because the top surface was the coolest portion of

each slab. It cooled quicker and experienced wider temperature excursions than the rest of the

slab, including the bottom surface, which was in

contact with the gravel. Figure 4 shows the temperatures of the slabs’ top surfaces and the temperature of surrounding air. A separate graph is

shown for each concrete section. The recording

period for each concrete section began at the time

shown in Table 2 and extends through midnight,

22 March. Figure 4 also shows the temperatures

from two points near the bottom surface of one

slab, and the temperature of one 7.6- × 15.2-cm

sample cylinder exposed to the cold.

Figure 4a shows the temperatures of the control concrete and the heated air in the shelter. The

shelter was heated for several days before 15

March to thaw the frozen ground. To facilitate

placement of the control concrete, two walls of

the shelter were removed at 10:30 a.m. on 15

March and replaced at noon. The air inside the

shelter cooled to –6.6°C by the time concreting

started, but, after the walls were replaced, the

shelter warmed up again. However, the shelter

Table 3. Properties of fresh concrete.

Temperature

inside the

Slump Air Unit wt. concrete

Mix (cm) (%) (kg/m3) (°C)

Control 5.1 3.2 2307 12.2

EY11L 14 3.2 2307 3.3

EY11H 14 4.7 2275 3.3

DP 12.7 8 2163 7.2

4

Figure 3. Plastic was placed over the antifreeze concrete cured outdoors.
5

15 16 17 18 19 20 21 22 23

March

Temperature ( ̊C)

35

30

25

20

15

10

5

0

–5

–10

Control

Air

15 16 17 18 19 20 21 22 23

March

Temperature ( ̊C)

10

5

0

–5

–10

–15

EY11L

Air

15 16 17 18 19 20 21 22 23

March

Temperature ( ̊C)

10

5

0

–5

–10

–15

EY11H

Air

20

15

–20

c. EY11H concrete and outside air.

Figure 4. Thermal history of test concretes.

a. Control concrete and heated air.

b. EY11L concrete and unheated shelter air.
6

15 16 17 18 19 20 21 22 23

March

Temperature ( ̊C)

10

5

0

–5

–10

–15

DP

Air

20

15

–20

15 16 17 18 19 20 21 22 23

March

Temperature ( ̊C)

0

–5

1.9 cm Below Slab Botton

2.54 cm Above Slab Bottom

5

-10

15 16 17 18 19 20 21 22 23

March

Temperature ( ̊C)

10

5

0

–5

–10

–15

Center of EY11L Cylinder in Unheated Shelter

d. DP concrete and outside air.

e. Temperature in gravel and in EY11L slab.

f. Center of EY11L cylinder in unheated shelter.

Figure 4 (cont’d). Thermal history of test concretes.
temperature fluctuated daily. The maximum of

29.7°C occurred at 4:10 p.m. on the 16th, and two

lows of –0.2°C and 0.4°C occurred at 3:30 a.m. on

the 19th and at 6:45 a.m. on the 20th respectively.

The two low temperatures were caused by a malfunction of the heating equipment. The heat was

turned off at about 4 p.m. on 22 March. The average air temperature in the shelter for the recording period was 10.5°C.

The control concrete was delivered to the site in

two separate shipments, at a temperature of about

12°C for each shipment. (All other concrete was

delivered in one truck per section.) By the time

both control shipments had been placed and the

shelter walls were reinstalled, the concrete had

cooled off to 1.3°C (Fig. 4a). It wasn’t until 5 p.m.

of that same day that the heat supplied by cement

hydration and the shelter warmed the concrete to

12°C. The concrete continued to warm until it

reached 20.3°C at 7 a.m., 16 March, in spite of the

air cooling to 9.4°C. Like the air, the concrete temperature fluctuates throughout the recording period. It reached a maximum temperature of

25.3°C at 4:10 p.m. on the 16th and a minimum of

3.8°C at 7:10 p.m. on the 20th, closely corresponding to the high and low shelter air temperatures.

The average temperature of the control concrete

through 4 p.m. on 22 March was 13.3°C. It never

dropped below zero during this period.

Two of the three antifreeze sections were

placed on 16 March, the coldest of the two days

that concrete containing antifreeze admixtures

was placed. The outdoor air temperature (Fig. 4c

and d) through midnight on the 16th averaged

–8.7°C, though it rose to slightly above freezing

for a short time by midday. The minimum outdoor air temperature of –16.5°C was recorded at

6:45 a.m. on 17 March. Winds created wind chills

down to –28°C. Thereafter, the outdoor air temperature became much milder; the average

through 4 p.m., 22 March, was –2.4°C.

Figure 4b shows the temperatures of the EY11L

concrete and the air inside the unheated shelter.

The EY11L mix was placed at 9:45 a.m., 16 March.

It was delivered at a temperature of 3.3°C. As was

done with the control section, two walls of the

unheated shelter were removed temporarily.

When exposed to the –10°C (but warming) air, the

concrete temperature dropped to 2°C, but almost

immediately began rising, reaching 4.3°C by 4

p.m. Then, the concrete temperature dropped to

–3°C, its lowest recorded temperature, at 3:30 a.m.

on 17 March. This concrete contained a low admixture dosage and had an expected freezing

point of around –3°C. Its average temperature

was 0.9°C through 4 p.m., 22 March.

Figure 4c shows the temperatures of the EY11H

concrete and the outdoor air. The freezing point of

this concrete was –5°C. The EY11H mix was cast

outdoors at 11:40 a.m., 16 March. It, too, began at

3.3°C. But, instead of cooling off when exposed to

the –7.3°C air, it warmed to 11.8°C at 2:10 p.m., before dropping off to –4.4°C at 7 a.m., 17 March. It

reached its lowest temperature of –5.5°C at 7 a.m.,

20 March, 4 days after being cast. Its average temperature was 2.4°C through 4 p.m., 22 March.

Figure 4d shows the temperatures of the DP

concrete and the outdoor air. The freezing point of

this admixture was –5°C. The DP concrete section

was cast outdoors at 1:10 p.m., 17 March. It was

delivered to the site at 7.2°C, when the air temperature was 4°C and falling. The concrete temperature rose to a high of 15.8°C at 2:30 p.m. on 17

March. Because of a data recorder malfunction,

concrete temperatures were not recorded after

midnight, 18 March. The average air temperature

from the time of placement to midnight, 18 March,

was –1.6°C and from placement through 4 p.m., 22

March, was –1°C. The average temperature of the

concrete through midnight, 18 March, was 6.3°C.

The DP concrete probably did not drop below

–5°C through 22 March.

Figure 4e shows the temperatures of two points

near the bottom surface of the EY11L slab. The

EY11L slab had the lowest average surface temperature of all the slabs. As can be seen in Figure

4e, the bottom surface of the concrete, which was

halfway between the two thermocouple positions,

could not have frozen. The lowest temperature of

the two thermocouples was –1.2°C, 21 hours after

the concrete was placed. Recall that the freezing

temperature of this concrete was –3°C. The EY11H

slab, with a –5°C freezing temperature, experienced the lowest single surface temperature of all

the slabs. Its bottom surface temperature reached

a low of about –3°C (not shown), 4 days after the

concrete was placed.

Figure 4f shows the temperatures of an EY11L

cylinder stored on grade in the unheated shelter.

The cylinder’s temperature dipped below –5°C on

several occasions, the first at 8:00 p.m. on 16

March, about 10 hours after it was cast. The average temperature of the cylinder through 4 p.m., 22

March, was –1.3°C.

Strength development

Several 7.6- × 15.2-cm cylindrical samples were

cast from each type of concrete and stored in two

7
8

locations: on grade next to the slabs, and overhead

in the heated enclosure. A concrete testing laboratory (Coleman Engineering Co., Iron Mountain,

Michigan) periodically tested the cylinders’ compressive strength.

Their compressive strengths cannot be used as

an indicator of the in-place strength of the antifreeze concrete because, as Figure 4f shows, the

cylinders probably froze. At CRREL, subsequent

petrographic analysis of the suspected frozen

cylinders revealed typical ice lens patterns.

Strengths reported by the testing laboratory indicate that the cylinders developed only about half

of their potential strength, which is indicative of

concrete that has frozen while curing.

Likewise, the strengths of the cylinders stored

overhead in the heated shelter were not considered useful information, other than to confirm

that the admixtures promoted strength in concrete

cured at above-freezing temperatures. They shed

little light on the in-place strength of the concrete

slabs.

The most interesting and useful results came

from cores drilled from each slab in the summer.

The cores showed that the antifreeze concrete was

at least as good as the control concrete in compressive strength and appearance. None of the slabs

showed signs of frost damage and all of the concrete exceeded minimum design strengths (Table

4). In fact, when it is considered that entrained

air can reduce compressive strength 3% for each

1% of entrained air (U.S. Department of the Interior, Water and Power Resources Service 1981; Kosmatka and Panarese 1988), and that the air contents were generally higher in the admixtured

concretes than in the control concrete (Table 3), the

strength of the admixtured concretes exceeded the

strength of the control concrete. Though air contents can change when a concrete hardens, the

core densities (Table 4) suggest that the concretes

retained their relative proportions of air.

Table 4. Test results from 9.2- × 13.3-cm

core samples drilled in July 1994.

Compressive Bulk

strength* density† Evidence of

Mix (Mpa) (g/cm3) past ice?

Control 46.7 2.31 No

DP 46.0 2.21 No

EY11L 50.6 2.32 No

EY11H 55.5 2.29 No

* Minimum design strength was 32 Mpa.

† Densities based on cylinder dimensions and

mass.

Cost comparison

Freeze protection is the primary cost-multiplier

of a concrete job done during the winter. Based on

the field tests, the main differences between normal winter concreting practice at the Soo and concreting done with antifreeze admixtures are the

heat, shelter, and labor needed to protect the normal concrete, and the chemicals in the antifreeze

concrete. Table 5 shows an estimate of the relative

surcharge, per slab, of each winter concreting

method. It is useful to know that the cost of readymix concrete at the Soo was $93.50/m3 the summer before this project and that placement would

double this cost.

DISCUSSION

Normal unprotected concrete would have frozen during this test. The freezing-point-depression and accelerated cure properties of the antifreeze concretes enabled them to resist freezing.

The best evidence that the concrete did not

freeze was obtained by examining drilled cores.

The core samples, taken from each slab 4 months

after construction and examined under a microscope, showed no signs of frost damage.

The drilled cores were also tested for compressive strength, which provided additional information that the admixtures produced a concrete

that was unaffected by the outdoor winter conditions.

Other than the cold weather, the major concern

during the test was that concrete was placed on a

subgrade that was significantly below the –5°C

protection capability of the admixtures at their

highest dosage, let alone at the low dosage. This

could mean that the bottom of the concrete would

be damaged by frost. Gavrish et al. (1974) reported that up to 16 times more heat is lost from a concrete slab to frozen ground than is lost to the air

during initial curing. From our data, however, it

was clear that the bottom of the concrete was free

from frost damage. The lowest slab-bottom temperature of the low dosage EY11 concrete was

about –1.2°C, 21 hours after placement, and for

the high dosage EY11 concrete it was –2.6°C, 4

Table 5. Winter surcharge estimate per slab.

Shelter Antifreeze

Erect $552 Concrete 5.1 m3

Materials $118 Dosage 97.1mL/kg cement

Heat $136 Cement 391 kg/m3

Dismantle $276 Admixture $0.80–$2.10/L

Total $1082 Total $155–$407
9

days after placement. At these temperatures and

by these times, even admixture-free concrete may

have been able to set and become resistant to

freezing.

The fact that the antifreeze concrete placed on

frozen ground didn’t suffer frost damage has implications for normal winter concreting, when

placing fresh concrete on frozen ground is prohibited because of the danger of freezing. In this

study, when the top surface temperature of the 15-

cm slab was above freezing, the bottom surface of

the slab did not develop ice. Recall that the concrete was placed on a gravel pad, free of ice. If the

concrete had been placed directly on the ground,

which contained ice, the situation may have

changed because ice can significantly increase

heat loss rates. In this case, air spaces among the

pieces of gravel probably slowed the heat loss

from the slab enough to prevent freezing. Also,

the accelerators in the admixture probably provided increased protection through increased heat

release during early hydration. More study is

needed to test the practice of placing admixturefree concrete on frozen ground.

The test showed that, at times, a plastic sheet

provided more than just protection against moisture loss. Figures 4b and c show that the concrete

under the plastic sheet was actually warmer than

the concrete inside the unheated shelter, at least

on sunny days. The sheet-covered concrete was 5

to 10°C warmer during the day on all but 21

March, which was a cloudy day. On that day, the

two concrete temperatures were nearly identical.

At night, the opposite occurred: the concrete inside the unheated shelter was

up to 1.5°C warmer. These observations can be explained by

the effect of the large volume of

air in the shelter. The plastic

sheet, having essentially no air

to heat up and cool off, allowed

the concrete to heat and cool

faster than could the concrete inside the shelter. The 6-day temperature of the concrete under

the plastic sheet averaged 2.4°C,

vs. 0.9°C for the concrete in the

unheated shelter. A blanket of

insulation would undoubtedly

have performed even more effectively.

Of special interest in these

tests was how the work would

progress in cold weather. The

workers at the Soo said that working outdoors

was much preferred to working in a confining,

though heated, enclosure. It was much easier to

place and finish the concrete where there was freedom of movement. The consensus was that outdoor concreting was practical down to –20°C, possibly lower, provided a heated shelter was available to warm up in periodically. At the Soo, the

personnel worked outdoors in windy –10°C

weather for 2-hour intervals. The finishing operation required no special tools, skills or precautions. The antifreeze concrete finished in the same

manner as normal concrete. Ice did not build up

on the cold metal tools as expected.

Concreting in winter costs more than during

the rest of the year. The extra costs in this test were

113% for the enclosure, and up to 43% for the admixture. Costs associated with antifreeze admixtures were more than offset by savings on protection requirements.

From a strength development standpoint, the

antifreeze concrete was equal to or better than the

concrete placed inside a heated enclosure. Dry

heat can create problems. In fact, if the temperature of concrete is not closely regulated, high temperatures can cause significant strength loss, as

shown in Figure 1 for the 40°C concrete.

The potential effect on the length of the construction season of being able to place and keep

concrete at –5°C, instead of at the current limit of

5°C, can be determined by looking at weather

records. The number of days that the maximum

air temperature at the Soo exceeded various low

temperatures are shown in Figure 5. As can be

Figure 5. Extension of construction season possible with various low temperature limits (unpublished chart from Horrigan, 1995).

100

0

200

300

400

5 0 –5 –10 -20

Days

Lowest Working Temperature ( ̊C)
10

seen, pushing the temperature envelope to –5°C

increases the length of the construction season by

nearly 80 days. More working days become available at lower temperatures, to the point that concreting is a year-round proposition without the

need for heat. The climate at the Soo is similar to

that of the coldest areas in the contiguous U.S.

CONCLUSION

The admixtures performed quite well. Data

from nearly 2 years of laboratory testing have

shown that the prototype admixtures do not harm

the concrete and that they are capable of protecting concrete down to –5°C. The field tests clearly

demonstrated that working with these new admixtures required no new skills. The concrete was

mixed at lower temperatures; the admixture was

dosed into the truck, as is normally done with

some admixtures today; and the concrete was finished in the usual manner. The major benefit was

that, once finished, the concrete was not damaged

by exposure to freezing temperatures. The only

protection used was a plastic sheet to cover

exposed areas to minimize moisture loss during

curing. In addition to all of this, a tremendous

amount of thermal energy was conserved and the

resulting concrete quality was excellent.

The potential effect of being able to place concrete at below-freezing temperatures is significant.

Pushing the winter concreting envelope from the

current 5°C limit to –5°C can extend the “normal”

construction season by around 2 months at the Soo.

Since this field test was conducted, the prototype admixtures have undergone additional

research and improvement. Such research will

likely produce commercial admixtures that outperform the present prototypes.

LITERATURE CITED

ACI (1988) Cold weather concreting. ACI 306-88.

Detroit, Michigan: American Concrete Institute.

Civil Engineering (1991) Antifreeze for your concrete. December 1991, p. 10.

Gavrish, Y. E., N.S. Khvorostovskya, and V.G.

Serbin (1974) Thermal behavior of concrete slab

on frozen ground bed. In Proceedings, The Second

International Symposium on Winter Concreting,

Moscow. Stroyizdat, vol. 1, p. 23–33. (Available as

CRREL Draft Translation 729.)

Korhonen, C.J. (1990) Antifreeze admixtures for

cold weather concreting: A literature review. USA

Cold Regions Research and Engineering Laboratory, Special Report 90-32.

Kosmatka, S. H., and W. C. Panarese (1988) Design

and Control of Concrete Mixtures, 13th edition. 5420

Old Orchard Road, Skokie, Illinois: Portland

Cement Association.

U.S. Department of the Interior, Water and Power

Resources Service (1981) Concrete Manual. U.S.

Department of the Interior, Water and Power

Resources Service. Washington, D.C.: Superintendent of Documents, U.S. Government Printing

Office, 8th edition,
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April 1997

Developing New Low-Temperature Admixtures for Concrete:

A Field Evaluation

Charles Korhohen, Brian Charest, and Kurt Romisch

U.S. Army Cold Regions Research and Engineering Laboratory

72 Lyme Road Special Report 97-9

Hanover, New Hampshire 03755-1290

Office of the Chief of Engineers

Washington, D.C. 20314-1000

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UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED UL

Two new admixtures, capable of preventing water from freezing, as well as increasing the hydration rate of

cement at below-freezing temperatures, were field tested at Sault Ste. Marie, Michigan. Concrete made with

the admixtures was placed on a frozen subgrade during a cold winter day and was allowed to cure thermally,

unprotected in the cold. Comparison to control concrete placed inside a heated shelter showed that the unprotected, admixtured concrete was equal to the control in strength and appearance. Work is continuing on the

development of these admixtures for commercial use.

Antifreeze admixture Freeze–thaw

Cold-weather concrete Winter construction

For conversion of SI units to non-SI units of measurement consult Standard Practice for Use of the International System of Units (SI),

ASTM Standard E380-93, published by the American Society for Testing and Materials, 1916 Race St., Philadelphia, Pa. 19103.