SPECIAL REPORT 96-28

Freezing Temperature Protection

Admixture for Portland Cement

Concrete

Charles J. Korhonen and John W. Brook October 1996
Abstract: A number of experimental admixtures were

compared to Pozzutec 20 admixture for their ability to

protect fresh concrete from freezing and for increasing

the rate of cement hydration at below-freezing temperatures. The commercial accelerator and low-temperature admixture Pozzutec 20 served as the reference admixture for this project as it has been a

successful product of Master Builders for winter concreting during the past several years. Over thirty-five

experimental admixture candidates were tested. Of

these, one experimental admixture, code-named EY11, a nonchloride admixture, outperformed all the others and was selected as the admixture to be considered for future commercialization. It was demonstrated

by laboratory evaluation that the Pozzutec 20 admixture did not contribute to corrosion of embedded steel

reinforcement. The EY-11 admixture, although still unHow to get copies of CRREL technical publications:

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der examination, also did not contribute to corrosion in

a newer and different laboratory test. Based on a

knowledge of its constituents, EY-11 is not expected to

contribute to corrosion under laboratory conditions or

in the field. The low and medium dosages (60 and

100 mL/kg [90 and 150 fl oz/cwt]), of EY-11 produced freeze–thaw-durable concrete, but the highest

dosage examined, 160 mL/kg (240 fl oz/cwt), did

not. The middle dosage (100 mL/kg) protected concrete down to the low-temperature goal of this project,

–5°C (23°F). The prototype admixture, EY-11, affords

superior low-temperature protection compared to existing accelerating admixtures, as well as good durability. Unfortunately, it did not provide the desirable

rapid setting and strength gain of concrete at abovefreezing temperatures that field engineers and concrete

technicians would like.
Special Report 96-28

Freezing Temperature Protection

Admixture for Portland Cement

Concrete

Charles J. Korhonen and John W. Brook October 1996

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 J. Korhonen, Research Civil Engineer, Civil

and Geotechnical Research Division, Research and Engineering Directorate, U.S.

Army Cold Regions Research and Engineering Laboratory (CRREL), Hanover, New

Hampshire, and by John W. Brook, Senior Research and Development Scientist,

retired, Master Builders, Inc. (MB), Cleveland, Ohio.

The investigation was conducted under the authority of the Corps Construction

Productivity Advancement Research (CPAR) program. Project approval was received in August 1991 and work began in April 1992. The research was completed in

December 1994.

Technical review of this report was provided by Edel R. Cortez, CRREL, and by

Brian E. Caine, Manager, Chemical Laboratory, and Dr. Charles Nmai, Manager,

Engineering Group, MB. The authors acknowledge the support of Brian Caine, Ray

Giangiacomo, James Zupanic (Youngstown State University), Robert Ryan, Jerry

Lewis, Matt Miltenberger, R. Davis, and Jesse Osborne of MB, and Brian Charest, Edel

Cortez, Charles Smith, and Christopher Berini of CRREL.

This publication reflects the personal views of the authors and does not suggest or

reflect the policy, practices, programs, or doctrine of the U.S. Army or Government

of the United States. 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
CONTENTS

Page

Preface ..................................................................................................................... ii

Introduction ............................................................................................................ 1

Background ........................................................................................................ 1

Objectives ........................................................................................................... 2

Scope ................................................................................................................... 3

Phase I: Evaluation of Pozzutec 20 ...................................................................... 3

Procedure ........................................................................................................... 3

Results and discussion ..................................................................................... 5

Phase II: Development of improved admixture ................................................ 11

Procedure ........................................................................................................... 11

Results and discussion ..................................................................................... 12

Phase III: Evaluation of improved admixture ................................................... 14

Procedure ........................................................................................................... 14

Results and discussion ..................................................................................... 14

Phase IV: Field application ................................................................................... 17

Procedure ........................................................................................................... 17

Results and discussion ..................................................................................... 18

Conclusions ............................................................................................................ 25

Recommendations ................................................................................................. 27

Literature cited ....................................................................................................... 27

Appendix A: Phase I, Task 1 strengths ............................................................... 29

Appendix B: Phase I, Task 5 critical strengths .................................................. 31

Appendix C: Phase II, mortar screening results................................................ 33

Appendix D: Phase II, concrete testing results .................................................. 35

Abstract ................................................................................................................... 39

ILLUSTRATIONS

Figure

1. Temperature histories of concrete with Types I and III cement,

various dosages of Pozzutec 20, cured at various temperatures ..... 6

2. Effect of temperature on strength gain of concrete ................................. 7

3. Lollipop specimens submerged half-height in 3% sodium chloride

solution ..................................................................................................... 8

4. Lollipop specimens submerged half-height in deionized water .......... 8

5. Effect of early age freezing on concrete strength .................................... 10

6. Strength gain of concrete made with EY-11 cured at –5°C compared

to control concrete cured at two above-freezing temperatures ........ 15

7. Lollipop specimens, 75- × 150-mm cylinders ponded half-height

in sodium chloride solution ................................................................... 16

iii
Figure Page

8. Lollipop specimens, 50- × 100-mm cylinders ponded half-height

in sodium chloride solution ................................................................ 16

9. Air temperatures from 7:30 a.m., 17 February, through 12:30 a.m.,

10 March 1994, at Hanover, New Hampshire .................................. 19

10. Temperature history of the Pozzutec 20 concrete slab placed on

grade at Hanover, New Hampshire ................................................... 19

11. Temperature history of the EY-11 concrete wall placed at 12:05 p.m.

on 18 February at Hanover, New Hampshire .................................. 20

12. Temperature history of the top surface of the control slab and the

heated air in the control shelter at Sault Ste. Marie, Michigan ...... 22

13. Temperature history of the top surface of the EY11L slab and

that of the outdoor air at Sault Ste. Marie, Michigan ...................... 22

14. Temperature history of the top surface of the EY11H slab and

that of the outdoor air at Sault Ste. Marie, Michigan ...................... 22

15. Temperature history of the center of mass of a 75- × 150-mm

cylinder of EY11L concrete stored on grade in the unheated

shelter at Sault Ste. Marie, Michigan.................................................. 23

16. Possible extension of construction season with various lowtemperature limits ................................................................................ 25

TABLES

Table

1. Chemical composition of Type I and Type III cement .......................... 2

2. The four phases of work ............................................................................ 3

3. Phase I tasks ................................................................................................. 3

4. Phase I test variables .................................................................................. 4

5. Phase I mixture identification ................................................................... 4

6. Equivalent insulation tests ........................................................................ 5

7. Durability factors for Pozzutec 20 concrete ............................................ 9

8. Equivalent insulation test results for concrete made with

Pozzutec 20 ............................................................................................ 9

9. Equivalent insulation values for 5.4-cm-thick wall maintained at

10°C for seven days .............................................................................. 10

10. Phase II tasks ............................................................................................... 11

11. Phase II, Task 1; mortar mixture proportions ......................................... 11

12. Phase II, Task 2; concrete mixture proportions ...................................... 12

13. Strength results from two trial admixtures in concrete with a

365-kg/m3

 cement factor and a 0.48 w/c .......................................... 12

14. Strength results from Pozzutec 20 and propylene glycol and urea

with a 420-kg/m3 cement factor and a 0.43 w/c .............................. 13

15. Strength results from three trial admixtures in concrete with a

365-kg/m3 cement factor and a 0.48 w/c .......................................... 13

16. Strength results from three trial admixtures in concrete with a

420-kg/m3 cement factor and a 0.43 w/c .......................................... 14

iv
Table Page

17. Phase III tasks .............................................................................................. 14

18. Compressive strength of the EY-11 mixtures ......................................... 14

19. Harmlessness corrosion results ................................................................ 15

20. Durability factors for Pozzutec 20 and EY-11 concrete ......................... 17

21. Equivalent insulation test results ............................................................. 17

22. Equivalent insulation values for 152-mm-thick wall maintained

at 10°C for seven days .......................................................................... 17

23. Mixture proportions ................................................................................... 18

24. Properties of fresh concrete ....................................................................... 19

25. Concrete placement time ........................................................................... 19

26. Strength results from pullout cylinders cast into the concrete ............ 20

27. Mix proportions .......................................................................................... 21

28. Concrete placement time ........................................................................... 21

29. Properties of fresh concrete ....................................................................... 21

30. Test results from 92- × 133-mm core samples drilled in July 1994 ...... 24

31. Winter cost estimate ................................................................................... 24

v
INTRODUCTION

Background

Development of an admixture capable of allowing fresh concrete to gain strength at belowfreezing temperatures without causing detrimental effects to the final product has long been a goal

of the concreting industry. Work on the problem

began several decades ago, with contributions

made by researchers from the former Soviet Union,

Scandinavia, and elsewhere (Korhonen 1990) who

showed that certain chemicals can significantly

depress the freezing point of the concrete mix

water, and that other chemicals can accelerate the

hydration rate of cement at very low temperatures. To date, however, there has been no comparable advancement of these or other chemicals

in the United States. Concerns over their potential adverse effects, such as increased risk of corrosion or chemical reaction with aggregate, have

discouraged serious consideration.

As a result, current U.S. winter concreting practices have remained unchanged for the past several decades. Concrete ingredients such as stone,

sand, and water must still be heated to melt all

ice, but not heated so highly as to cause rapid set

within the concrete mixing and handling equipment, 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

ensure adequate strength to allow early removal

of forms for their reuse.

The American Concrete Institute (ACI) sets the

standards for winter concreting. It recommends

that freshly placed concrete must be protected

from freezing by maintaining its temperature at

or above 5°C (40°F), preferably at or above 10°C

(50°F) (ACI 1988) until it has sufficiently cured to

serve its intended purpose. Finishing operations

take longer as temperatures dip to 5°C (40°F) and

below, and forms cannot be stripped as fast as

they can during the summer. The rate of concrete

strength gain is slowed. At a few degrees below

zero, the hydration rate of cement continues to

slow and the mix water begins to turn into ice; at

–3°C (27°F), 90% of the water will freeze (Korhonen

1990). If freezing occurs, upon thawing the concrete may lose half its strength.

There are procedures today to protect newly

placed concrete from freezing and to ensure adequate strength to produce concrete that meets

construction needs for strength and durability.

However, this protection is costly. It has been

estimated that the U.S. construction industry

spends $800 million (Civil Engineering 1991) every year on measures to protect fresh concrete

from freezing. An admixture that would alleviate

this expense would be of great economic benefit.

Master Builders (MB) established renewed interest in this topic in the late 1980s by marketing

this country’s first nonchloride, low-temperature

admixture: Pozzutec 20. Though Pozzutec 20 depresses the freezing point of water a few degrees,

its major cold weather advantage is that it has

been specially formulated to accelerate setting time

and strength gain in concrete. When used at recommended dosages, Pozzutec 20 greatly increases

the rate of cement hydration, generating more

heat earlier than would be generated by normal

concrete, even those containing conventional accelerators. This extra heat usually provides enough

protection to prevent concrete from freezing until

it has developed sufficient strength to resist ice

damage. After the concrete has reached this level

of self-protection, it continues to gain strength

even if its internal temperature should fall below

freezing. Pozzutec 20 is recommended for use at

Freezing Temperature Protection Admixture

for Portland Cement Concrete

CHARLES J. KORHONEN AND JOHN W. BROOK
ambient temperatures down to –7°C (20°F) with an

application dosage of up to 60 mL/kg (90 fl oz/

cwt).

In an effort to expand upon the success of

Pozzutec 20 and to develop the long-sought freezing protection admixture, Master Builders and

the U.S. Army Cold Regions Research and Engineering Laboratory entered into a cooperative research project. This project was conducted under

the authority of the Corps of Engineers Construction Productivity Advancement Research (CPAR)

program. Because the Federal Government is a

big buyer of construction services and the Corps

of Engineers uses a lot of concrete, a new winter

admixture would produce savings for the Government and provide a benefit to the U.S.

economy. This is the final report of Fiscal Year

1990 project “Freezing Temperature Protection

Admixture for Portland Cement Concrete.”

Objectives

The two prime objectives of this study were to

explore the low-temperature performance of

Pozzutec 20 and to develop a prototype admixture that would protect fresh concrete from freezing while increasing the rate of cement hydration

when the internal temperature of the concrete is

below 0°C (32°F).

One important constraint in developing lowtemperature admixtures for concrete is that no

standards of acceptance criteria are available.

Chemical admixtures are currently classified by

ASTM C 494 into seven categories of set-controlling and water-reducing admixtures. The categories include Type C, accelerating, and Type E,

water reducing and accelerating admixtures, each

tested at 23 ± 1.7°C (73 ± 3°F), well above freezing. It was therefore necessary at the start of this

project to define a freezing protection admixture.

Freezing protection admixtures were defined as

chemicals that should:

Depress the freezing point of water

Promote strength gain of concrete at low

temperatures

Not interfere with concrete strength gain

at normal, above-freezing temperatures

Maintain workability of the concrete in

freezing conditions

Achieve reasonable concrete set times

(this does not necessarily mean accelerated

set times)

Produce freeze–thaw-durable concrete

Not react unduly with silica aggregate

Not contribute to corrosion of embedded steel reinforcement, or to steel on which

concrete is placed

Be cost-effective

Further, to avoid the necessity of conducting

long-term testing of experimental admixtures to

determine that they meet these requirements, the

decision was made that only chemicals currently

being used in concrete be considered for initial

evaluation. This decision provided us with reasonable assurance that the chemicals have already

been tested for their effect on concrete. As experience was gained with this new technology, other

chemicals could be added to the study. It was also

decided that the initial low-temperature goal

would be set at –5°C (23°F), with –10°C (14°F)

being a possible ultimate objective, and that the

concrete cured at these low temperatures should

gain strength at least as rapidly as normal concrete at 5°C (40°F), the accepted low-temperature

limit for winter concreting in the United States

(ACI 1988).

Finally, to ensure reasonable continuity during

the nearly two years of laboratory testing, both

MB and CRREL used the same cement, air entraining agent, and plasticizer. The cement selected was an ASTM Type I cement from Blue

Circle Cement, Tulsa, Oklahoma, with a Blaine

fineness of 3460 cm2/g (Table 1). A Type III cement was used at CRREL for some Phase I mixtures (Table 1). The air entraining agent was a

neutralized vinsol resin, MB-VR, and the plasticizer was a high-range water reducer, Rheobuild

1000 (naphthalene sulfonate-formaldehyde condensate, calcium salt), both from Master Builders.

Each party used its local aggregates and water.

The coarse and fine aggregates used by CRREL

Table 1. Chemical composition

of Type I and Type III cement.

Type I Type III

Compound (%) (%)

SiO2 20.85 20.95

Al2O3 4.75 5.44

Fe2O3 2.26 2.36

CaO 63.92 62.57

K2O 0.70 0.75

MgO 2.34 2.16

SO3 3.14 4.20

C3S 58.0 43.6

C2S 16.0 27.2

C3A 9.0 10.4

C4AF 7.0 7.2

LOI 1.18 1.09

Na2O (Eq) 0.87 0.80

2
had bulk specific gravities of 2.89 and 2.67 and an

absorption of 0.5 and 1.1 percent, respectively.

The coarse aggregate was crushed ledge with a

gradation that fit between ASTM sizes no. 6 and

7. The fine aggregate was a natural sand with a

fineness modulus of 2.80. The coarse and fine

aggregate used by MB had specific gravities of

2.84 and 2.58, respectively. The coarse aggregate

was a Drummond Island limestone while the fine

aggregate was a Hugo sand. Tap water was used

for the mix water at each lab.

Scope

A series of laboratory and field tests was conducted to evaluate the effect of various chemicals

on properties of concrete. Master Builders developed chemical formulations for testing and conducted the laboratory studies aimed at defining

strength and chemical reactions of the formulations. CRREL conducted the low-temperature

laboratory and field studies to verify expected

performance of the admixtures.

This project consisted of four phases of experimental work (Table 2). Phase I involved a comprehensive laboratory testing of Pozzutec 20.

Phase II conducted a laboratory screening of numerous potentially new freezing protection admixtures, selecting the best for further testing and

evaluation. Phase III used a series of tests similar

to those performed on Pozzutec 20 in Phase I on

the best admixture developed in Phase II. Phase

IV consisted of two cold weather field trials.

PHASE I: EVALUATION

OF POZZUTEC 20

Procedure

The objective of Phase I was to characterize the

low-temperature performance of Pozzutec 20 and,

in the process, establish a test protocol for Phase

III. Phase I was divided into five experimental

tasks (Table 3).

Task 1: Strength vs. temperature

The objective of this task was to develop a

relationship between the strength gain of concrete and its curing temperature. The test procedure consisted of mixing and casting the concrete

at room temperature. A few minutes after casting, the cylinders were placed into one of several

curing rooms set at prescribed temperatures. Concrete temperatures in each of the rooms were

monitored for the first seven days by thermocouples cast into dummy cylinders. A data logger

recorded the temperatures in each dummy cylinder as well as the ambient temperature. All cylinders were sealed to prevent evaporation from the

concrete. At various ages, sets of three cylinders

were removed from the curing rooms, allowed to

warm up to 10°C (50°F), if necessary, and tested

for unconfined compressive strength according

to ASTM C 39.

The concrete was prepared according to ACI

211.1 standards. Fourteen mixes, each with a volume of 0.057 m3 (2.0 ft3) were batched, twelve

corresponding to three cement factors and four

admixture dosages for Type I cement, and two

for one cement factor with Type III cement and

two dosages of admixture (Table 4). Sixty-five

cylinders (75 × 150 mm [3 × 6 in.]) were cast per

mix (4 ages × 5 temperatures × 3 replicate specimens + 5 dummies).

Each cylinder was identified by three numbers

(Table 5): cement factor, admixture dosage, and

curing temperature. For example, mix (2,0,–5) contained the cement factor 2 (365 kg/m3 [611 lb/

yd3]) and no admixture cured at –5°C. The mixtures containing Type III cement were identified

by an asterisk (*) preceding the three-digit label.

This scheme is used throughout this report.

Once cast, the cylinders were placed into 20, 5,

–5, –10, and –20°C (70, 40, 23, 14, –4°F) rooms

within 30–45 min of addition of the mix water.

This ensured that essentially no strength gain took

place at anything but the appropriate curing temperature. The cylinders remained in each room

Table 2. The four phases of work.

Phase Description

I Evaluation of Pozzutec 20

II Development of improved admixture

III Evaluation of improved admixture

IV Field application

Table 3. Phase I tasks.

Task Description

1 Strength vs. temperature

2 Corrosion potential

3 Durability

4 Equivalent insulation

5 Critical strength

3
until tested or until 28 days. After 28 days, all

untested cylinders were placed in the 20°C (70°F)

room for 28 days of additional curing. This additional curing showed whether any permanent

strength loss was caused by the freezing temperatures.

Task 2: Corrosion potential

The potential of Pozzutec 20 to corrode reinforcing steel was tested according to two different procedures: initially via the well-known procedure reported in FHWA/RD-86/193 of the

Federal Highway Administration (this method

was the predecessor of ASTM G 109, a modification of and more reliable one than that of the

FHWA) and the MB-labeled “Lollipop Microcell

Corrosion Test.” The latter test, based on several

references (Sagues 1987, Dawson and Langford

1988, Aguilar et al. 1990, and Tourney and Berke

1993) uses a lower w/c ratio than the ASTM

method, thereby providing a better quality concrete. The lollipop procedure uses 75- × 150-mm

(3 × 6 in.) cylindrical mortar specimens, each fitted with an axially located No. 4 reinforcing bar

positioned 31.8 mm (1.25 in.) off the bottom of the

cylinder. The rebar protrudes out from the top of

each specimen. In the test, six specimens were

cast from two mortar mixtures: one mixture with

no admixture, and one with Pozzutec 20 dosed at

60 mL/kg (90 fl oz/cwt). Three of the six specimens from each of the two mixtures were submerged to a depth of 75 mm (3 in.) in a 3% sodium chloride solution, and the other three

specimens were partially submerged in deionized water. Another mixture was also prepared

with a Pozzutec 20 dose of 100 mL/kg (150 fl oz/

cwt), from which only three specimens were cast

and placed in the sodium chloride solution. All

specimens were made with standard ASTM C 109

mortar with a 0.485 w/c. They were cured at

100% relative humidity according to normal ACI

accepted practice. The deionized water provided

a nonaggressive environment and the sodium

chloride solution an aggressive one. The specimens were monitored for corrosion by regularly

recording the reinforcing bar‘s half-cell potential

using ASTM C 876, and periodically running impedance spectroscopy to approximate the corrosion rate. Testing, which was expected to run for

up to two years, began during April 1994 and was

completed after 1 1/2 years in October 1995, when

all specimens in chloride solution began corroding. Specimens in sodium chloride solution were

found to have corroded only under an epoxy coating upon final inspection.

Task 3: Durability

The resistance of concrete beams to deterioration from repeated cycles of freezing and thawing

was tested according to ASTM C 666, Procedure

A. Pozzutec 20 was tested at two dosages: 60 and

100 mL/kg (90 and 150 fl oz/cwt). The concrete

for the beams was made with a cement factor of

365 kg/m3 (611 lb/yd3), a w/c of 0.434 for the

concrete made with Pozzutec 20 (for the admixture provides water reduction) and 0.45 for plain

concrete, and an entrained air content of 6%. Three

beams were made from each mix, each beam measuring 75 × 102 × 406 mm (3 × 4 × 16 in.). They

were moist-cured for 14 days, then wrapped in

plastic and stored in a freezer until tested. All

beams were cycled through 300 freezing and thawing cycles or until failure, whichever occurred

first. Changes in relative dynamic modulus derived from resonant frequency readings were used

to monitor the deterioration. Criteria of ASTM C

Table 4. Phase I test variables.

Variable Quantity

Cement factors 308, 365, 420 kg/m3

(517, 611, and 705 lb/yd3)

Pozzutec 20 0, 40, 60, 100 mL/kg

(0, 60, 90, and 150 fl oz/cwt†)

Test ages 7, 14, 28, and 56 days

Curing temperatures 20, 5, –5, –10, and –20°C

(70, 40, 23, 14, –4°F)

w/c ratios 0.44, 0.48, and 0.52 for the 308,

365, and 420 cement factor

mixtures, respectively

Cement types I and III (Type III w/mix [*2,2]

and [*2,0])

Plasticizer For the 308 factor mixture only

† cwt denotes 100 lb of cement.

* Denotes Type III cement.

Table 5. Phase I mixture identification.

kg/m3 Admixture mL/kg

Cement factor (lb/yd3) dosage (fl oz/cwt)

1 308 (517) 0 0 (0)

2 365 (611) 1 40 (60)

3 420 (705) 2 60 (90)

— — 3 100 (150)

4
494 indicate that adequate F/T durability is expected of concrete that provides a durability factor (DF) of 80 or greater.

Task 4: Equivalent insulation

The American Concrete Institute (ACI 1988)

specifies that concrete placed during cold weather

should be maintained at a certain temperature for

a given amount of time. For example, ACI provides a series of tables outlining the amount of

insulation that is needed to maintain concrete at

10°C (50°F) for up to seven days. The amount of

insulation required is related to the ambient temperature, the shape of the structure, and the cement factor of the concrete. Because Pozzutec 20

accelerates the generation of heat from cement

during the first few days, concrete made with this

admixture should require less thermal protection

than admixture-free concrete. The objective of this

task was to determine the minimum ambient temperature at which an uninsulated cylinder of concrete made with Pozzutec 20 can be cured to produce a compressive strength equal to that of

admixture-free concrete cured at 10°C (50°F). This

minimum curing temperature could then be compared to the ACI tables to determine the amount

of insulation that would have been necessary to

protect normal concrete if cured at that same low

temperature. This insulation value was termed

“equivalent insulation,” signifying the amount of

insulation that Pozzutec 20 could safely replace.

The test consisted of making three batches of

concrete, each with a Type I cement and a different dosage of Pozzutec 20. The concrete was mixed

and cast into numerous 75- × 150-mm (3 × 6 in.)

cylinder molds, and then capped and distributed

among various curing rooms, each maintained at

a different temperature. At 7, 14, and 28 days,

three cylinders were removed from each room

and compression-tested after the cylinders were

warmed up to 10°C (50°F). Two additional batches

of concrete made with Type III cement tested the

value of using a high early strength cement. Table

6 gives the test makeup.

Task 5: Critical strength

Concrete is susceptible to ice damage at early

age because either its pore structure is underdeveloped or its moisture content is too high. As a

concrete matures, its water chemically combines

with cement, with the result that the concrete

increases in strength and decreases in freezable

water content. At some strength the quantity of

freezable water falls below a critical level, which

creates empty space within the concrete, enabling

the concrete to accommodate the growth of ice

crystals without being damaged. Concrete that

attains a compressive strength of 3.5 MPa (500

psi), the critical strength, is expected to be resistant to one cycle of freezing and thawing (ACI

1988). The objective of this test was to determine

if Pozzutec 20 affected this value.

The test was accomplished by allowing 75- ×

150-mm (3 × 6 in.) cylinders of fresh concrete to

cure at room temperature until they attained a

compressive strength of 1.7, 3.4, and 5.2 MPa (250,

500, and 750 psi). They were then transferred to a

–20°C (–4°F) freezing room overnight, after which

they were returned to room temperature and

cured until being strength-tested after 3, 7, and 28

days. The strengths of the once-frozen cylinders

were compared to control cylinders that were

never frozen to determine if the various freezing

scenarios caused a loss of strength.

Results and discussion

Task 1: Strength vs. temperature

Strength gain of concrete is the result of chemical and physical reactions between cement and

water. At room temperature, the reaction process

is most easily observed as a rise in temperature of

curing concrete. The amount of temperature rise

depends on how quickly the cement hydrates and

how quickly the generated heat is lost from the

concrete to the outside environment. Figure 1

shows typical temperature histories for 75- × 150-

mm (3 × 6 in.) cylinders of concrete cured at various temperatures. Results for the 308-kg/m3 (517

lb/yd3) mixes are not provided, as these mixes

tended to segregate when Pozzutec 20 was added.

Because this is considered a low cement content

for winter concreting, work with this cement factor was not pursued further.

Figures 1a, 1b, and 1c show the effect of cement type, cement amount, and Pozzutec 20 on

the temperature of curing concrete. It should be

noted that these figures do not represent field

conditions, as most field structures are more masTable 6. Equivalent insulation tests.

Cure temperature

Mixture ID °C (°F)

2,0 10 (50)

2,1 4, 2, 0, –2 (40, 35, 32, 28)

2,2 4, 2, 0, –2 (40, 35, 32, 28)

2,3 4, 2, 0, –2 (40, 35, 32, 28)

*2,0 4, 2, 0, –2 (40, 35, 32, 28)

*2,2 4, 2, 0, –2 (40, 35, 32, 28)

*Denotes Type III cement.

5
30

28

26

24

22

200 25 50 75 100 125 150 175

Time (hrs)

Temperature (°C)

Air

2, 0

2, 1

2, 2

2, 3

30

28

26

24

22

20 0 25 50 75 100 125 150 175

Time (hrs)

Temperature (°C)

Air

3, 0

3, 2

30

28

26

24

22

20 0 25 50 75 100 125 150 175

Time (hrs)

Temperature (°C)

Air

*2, 0 *2, 2

Temperature (°C)

Time (hrs)

40

20

0

– 10

– 20

0 50 100 150

10

30

a. Mixtures 2,3; 2,2; 2,1; and 2,0.

b. Mixtures 3,0 and 3,2.

c. Mixtures *2,0 and *2,2.

d. All curves represent mixture 2,3.

Figure 1. Temperature histories of concrete with Types I and III cement, various dosages of Pozzutec 20,

cured at various temperatures.

6
sive than the small samples tested in this task and

would likely produce higher concrete temperatures. However, the referenced curves clearly demonstrate the accelerating effect of Pozzutec 20. In

all three figures, increased dosages of this admixture caused the temperature of the concrete to

rise more quickly and attain higher temperatures

than did lower dosages. For example, Figure 1a

shows that mixture 2,3 produced a concrete temperature that was about 2°C (3.6°F) higher than

mixture 2,0 and about 1°C (1.8°F) higher than

mixtures 2,1 and 2,2. Comparing Figure 1a to 1b

shows that increasing the cement content has the

same accelerating effect as does adding Pozzutec

20 to the mix. The 3,0 mixture, containing the

high cement factor (420 kg/m3) and no admixture, produced a concrete temperature that was

nearly identical to the 2,3 mixture, containing the

middle cement factor (365 kg/m3) and Pozzutec

20. Comparing Figures 1b to 1c shows that the

high early strength cement produced the same

temperature that was produced by a higher

amount of normal cement.

Figure 1d shows a typical temperature history

of samples cured in each of the five curing rooms.

Samples stored at room temperature briefly rise

in temperature before cooling to room temperature at about 30 hours. The heat loss for the

samples in the other rooms was rapid enough to

preclude any rise in temperature. The samples

quickly cooled from about 20°C (70°F) to ambient

temperature. Within eight hours the sample in

the 5°C (40°F) room cooled to ambient while those

in the three colder rooms cooled to below freezing within five hours, showing that essentially all

strength gained by the samples in the cold rooms

occurred at the temperature of the particular curing room. Therefore, the cold room temperature

can be thought of as the temperature of the concrete.

Figure 2 shows the two most important findings from this task. A complete list of strength

results is provided in Appendix A. As was done

with the temperature measurements, the strength

results for the 308-kg/m3 (517 lb/yd3) mixes are

not provided due to segregation of this mixture.

The first finding of this task was that Pozzutec

20 not only accelerated early strength gain in concrete but that it also enhanced ultimate strength.

This result can be seen in Figure 2 by comparing

the room-temperature strength of the control concrete (2,0,20) to those of the three concretes made

with Pozzutec 20, cured at room temperature.

The low, medium, and high dosages of Pozzutec

20 increased the seven-day strength of concrete

by 5, 16, and 17 percent, respectively, and that of

the 56-day strengths by 8, 18, and 30 percent,

respectively. The second finding was that none of

the Pozzutec 20 dosages produced acceptable

strengths when cured at –5, –10, or –20°C (23, 14,

–4°F); it is probable that mass concrete produced

in the field with higher dosages (90 fl oz) of

Pozzutec 20 and curing temperatures above 14°F

would have acceptable compressive strengths. The

initial goal of this project was to produce an admixture that would promote strength in concrete

60

40

20

0 20 40 60 80

Age (days)

Compression Strength (MPa)

Room Temperature

2, 0, 20

2, 1, 20

2, 2, 20

2, 3, 20

ACI @ 5 °C

2, 3, – 5 °C

2, 3, – 10 °C

2, 3, – 20 °C

Figure 2. Effect of temperature on strength gain of concrete. The dotted

lines show the strength gain of control concrete at 20°C (70°F) and 5°C

(40°F). The 5°C (40°F) line is based on guidance from ACI (1988). All

results are for concrete made with a 365-kg/m3 (611 lb/yd3) cement factor

cured at a given temperature for 28 days, followed by 28 days of curing at

room temperature.

7
Corr.

Line

Pozzutec 20

@ 100 mL/kg

Pozzutec 20

@ 60 mL/kg

Reference

Weeks

Potential (– mV vs. SCE)

500

400

300

200

100

0 10 20 30 40 50 60 70 80

Pozzutec 20

@ 60 mL/kg

Potential (– mV vs. SCE)

Weeks

10 20 30 40 50 60 70 80

Reference

200

160

120

80

40

0

Figure 3. Lollipop specimens submerged half-height in 3% sodium chloride solution.

Figure 4. Lollipop specimens submerged half-height in deionized water.

cured at –5°C (23°F) at the same rate as that in

control concrete cured at 5°C (40°F). As can be

seen, the 7-, 14-, and 28-day strengths of the high

dosage concrete cured at –5°C (23°F) were significantly below that of the ACI standard for 5°C

(40°F) concrete. Strength gain at –10 and –20°C

(14 and –4°F) was even lower (see Fig. 2). This

does not necessarily mean that the Pozzutec concrete has been damaged by freezing, as this concrete displayed a remarkable recovery in strength

by 56 days when brought back to room temperature. It does suggest, however, that a new admixture would have to be developed to fully satisfy

the low-temperature goal of this project.

Task 2: Corrosion potential

The lollipop test results show that mortars

treated with 60 mL/kg (90 fl oz/cwt) of Pozzutec

20 are practically identical to admixture-free mortar. Figures 3 and 4 are graphs of the average

potentials from three specimens over a 1 1/2-year

period. There is no exact potential identifying the

initiation of corrosion. ASTM C 876 identifies potentials more positive than –200 mV vs. copper

sulfate reference electrodes as passive or noncorrosive behavior. Potentials between –200 and

–350 mV are an indication that corrosion has initiated, and potentials more negative than –350 mV

indicate a high probability of corrosion. Since our

8
test used a saturated calomel electrode (SCE), 60

mV should by added to the ASTM values to make

them useful to our readings (to convert to mV

SCE). Based on this guidance, potential indicative

of corrosion for a saturated calomel electrode is

–290 mV. The admixture-free specimens and the

specimens containing both dosages of Pozzutec

20 partially submerged in 3% sodium chloride

solution showed beginning signs of corrosion (Fig.

3). The interest, however, is that the Pozzutec 20

did not increase the level of corrosion when compared to the reference. All specimens in deionized water show no indication of corrosion. Thus,

the Pozzutec 20 did not adversely affect the mortar from the corrosion point of view.

Previous testing by others (Nmai et al. 1994)

corroborates the above results by showing that

mortar containing 60 mL/kg (90 fl oz/cwt) of

Pozzutec 20 and tested by the aforementioned

method of FHWA over the 50-week examination

period showed no sign of rebar corrosion. The

FHWA test, also known as the modified Southern

Climate Accelerated Corrosion Test, subjects the

top surface of concrete slabs, embedded with two

layers of rebar, to intermittent ponding with 15%

sodium chloride solution. The presence of corrosion is determined by the voltage drop between

the layers of rebar.

Task 3: Durability

Table 7 shows the results from subjecting concrete beams to up to 300 cycles of freezing and

thawing according to ASTM C 666, Procedure A.

Freeze–thaw deterioration was monitored by measuring the relative dynamic modulus of elasticity

of each concrete beam according to ASTM C 215.

Criteria of ASTM C 494 indicate that concrete is of

adequate durability if it maintains a durability

factor of greater than 80 after 300 freeze–thaw

cycles. The durability factor is the relative dynamic modulus of elasticity, expressed as percent, at the end of testing multiplied by the fraction of the number of test cycles conducted to the

specified number of cycles (300 for this project).

As seen in the table, the control and Pozzutec 20

mixture dosed at 60 mL/kg (90 fl oz/cwt) performed well. They both had durability factors of

99 at the end of the test. The 100 mL/kg (150 fl

oz/cwt), on the other hand, failed after 204 cycles

of freezing and thawing. The lower dosage (90 fl

oz) of Pozzutec is the maximum dosage recommended by Master Builders.

Task 4: Equivalent insulation

The minimum temperature at which concrete

with Pozzutec 20 can be cured to produce compressive strengths equal to that of control concrete cured at 10°C (50°F) was determined. Table

8 shows the strength of the various concrete mixtures studied. As can be seen, the minimum temperature for the 40-mL/kg (60 fl oz/cwt) dosage

of Pozzutec 20 (mixture 2,1) was 2°C (35.6°F),

where its strength equaled or bettered that of the

control at all ages. The 60 (90) and 100 (150) mL/

kg (fl oz/cwt) had minimum temperatures of 1

and 0°C, respectively. For the mixture made with

high early strength cement, the zero dose and 60

mL/kg (90 fl oz/cwt) dose had minimum temperatures of –2 and –4°C (28.4 and 24.8°F), respectively.

Table 7. Durability factors for Pozzutec 20 concrete.

Pozzutec 20 dosage—mL/kg (fl oz/cwt)

None 60 (90) 100 (150)

Durability factor 99 99 Failed

Table 8. Equivalent insulation test results for concrete made with Pozzutec 20.

Compressive strength—MPa (psi)

Mixture ID 7 days 14 days 28 days

2,0,10 (control) 23.5 (3405) 28.5 (4131) 33.1 (4800)

2,1,4 23.7 (3442) 29.6 (4291) 33.0 (4791)

2,1,2 24.0 (3475) 30.0 (4357) 34.7 (5027)

2,1,0 22.6 (3282) 27.8 (4037) 33.8 (4899)

2,1,–2 19.9 (2881) 26.1 (3782) 30.5 (4428)

2,2,4 25.5 (3697) 31.7 (4593) 35.5 (5154)

2,2,2 24.4 (3532) 31.1 (4513) 35.8 (5197)

2,2,0 22.4 (3524) 29.1 (4220) 33.4 (4847)

2,2,–2 20.3 (2947) 27.2 (3942) 32.3 (4678)

2,3,4 25.9 (3753) 30.2 (4380) 36.4 (5281)

2,3,2 25.8 (3739) 31.9 (4630) 38.4 (5564)

2,3,0 24.3 (3527) 29.6 (4296) 36.3 (5262)

2,3,–2 19.7 (2862) 28.9 (4186) 33.8 (4899)

*2,0,4 27.2 (3942) 34.8 (5041) 38.7 (5612)

*2,0,2 27.2 (3937) 35.9 (5210) 37.5 (5432)

*2,0,0 26.3 (3810) 33.5 (4857) 32.8 (4763)

*2,0,–2 24.2 (3503) 30.4 (4409) 34.4 (4984)

*2,2,4 30.5 (4418) 35.8 (5197) 41.8 (6059)

*2,2,2 29.8 (4319) 37.0 (5366) 40.0 (5805)

*2,2,0 28.6 (4140) 35.0 (5069) 39.5 (5734)

*2,2,–2 26.9 (3895) 35.0 (5074) 39.4 (5720)

* Denotes Type III cement.

9
Table 9 shows the amount of insulation that

the various mixtures tested can replace. The table

is based on ACI requirements to maintain a 150-

mm- (6 in.) thick wall of concrete made with Type

I cement at a cement factor of 365 kg/m3 (611 lb/

yd3) at 10°C (50°F) for seven days. For instance,

according to ACI, an ambient air temperature of

0°C (32°F) requires insulation to have a thermal

resistance value of 1.2 m2 K/W (6.9 hr ft2 F/Btu),

which is equivalent to 56 mm (2.2 in.) of fibrous

glass insulation. Pozzutec 20 dosed at 100 mL/kg

(150 fl oz/cwt) is equivalent to that amount of

insulation (Table 9).

Task 5: Critical strength

The objective of this task was to determine if

Pozzutec 20 affected the minimum strength at

which concrete can be frozen without being frostdamaged. The critical freezing strength of normal

air-entrained concrete, according to ACI 1988, is

3.5 MPa (500 psi). A complete list of strength

results at all test ages is provided in Appendix B.

Figure 5 highlights this data by showing the 28-

day strengths for the 365-kg/m3 (611 lb/yd3) cement factor of Type I and III cement. These data

provide evidence of the effect of Pozzutec 20 on

the critical freezing strength of concrete.

Before discussing the effects of Pozzutec 20, it

is worth noting in Figure 5 that the three admixture-free concretes, i.e., (2,0), (3,0), and (*2,0), were

unaffected by one cycle of freezing and thawing

once they had attained a compressive strength of

3.4 MPa (500 psi). The freezing actually produced

a slightly stronger concrete for the Type I cement

and showed no ill effect for the Type III cement. It

is interesting to note that the 3.5 MPa (500 psi)

critical strength value is for air-entrained concrete. The concretes in this study were non-airentrained. Thus, the real critical strength is probably less than that given by ACI.

The addition of Pozzutec 20 to the concrete

Table 9. Equivalent insulation values for 5.4-cm- (6 in.) thick

wall maintained at 10°C (50°F) for seven days.

Air temperature Required thermal resistance Equivalent fibrous

Mixture °C (°F) m2 K/W (hr ft2 F/Btu) glass—mm (in.)

2,1 2 (37) 1.0 (5.7) 47 (1.8)

2,2 1 (34) 1.1 (6.3) 52 (2.0)

2,3 0 (32) 1.2 (6.9) 56 (2.2)

*2,0 –2 (28) 1.4 (8.1) 66 (2.6)

*2,2 –4 (25) 1.6 (9.2) 75 (3.0)

* Denotes Type III cement.

c.

50

40

30

20

10

0

*2, 0 *2, 2

b.

60

40

20

0

3, 0 3, 1 3, 2 3, 3

Room a.

1.7 MPa

3.4 MPa

5.2 MPa

50

40

30

20

10

0

2, 0 2, 1 2, 2 2, 3

Compressive Strength (MPa)

Figure 5. Effect of early age freezing on concrete strength. The concretes were placed in a

–20°C (–4°F) room for 24 hours after they

attained a specified compressive strength. They

were then removed from the cold room and

cured at room temperature. This graph compares the 28-day strength of control concrete

that was never frozen to those of the concretes

that were frozen once.

had a positive effect on when concrete

can first be frozen. For both of the Type

I cement mixtures (Fig. 5a and b),

Pozzutec 20 produced a 28-day strength

that exceeded that of the admixturefree control, regardless of the strength

at which the concrete was frozen. The

exception to this was for the Type III

cement mixture (Fig. 5c), where Pozzutec 20 caused a 5% decrease in the 28-

10
and 28 days. This was later changed to three,

seven, and 28 days because the one-day strengths

were too low to be of value in this screening process.

Three series of trial admixtures were created,

coded EX, EY, and EZ, along with two others

modeled after Pozzutec 20, for a total of 35 solutions.

Task 2: Concrete testing

The best trial admixtures from Task 1 were

tested in concrete. Mixing took place at room temperature in a 0.17-m3 (6 ft3) drum mixer rotating

at 18 rpm for five minutes. The test specimens,

100- × 200-mm (4 × 8 in.) cylinders, were cast and

divided into two groups. One group was cured at

room temperature and one at –10°C (14°F) for

one, seven, and 28 days. All specimens from the

cold room were thawed at room temperature for

four to six hours (the amount of time necessary to

day strength when the concrete was frozen at the

1.7-MPa (250 psi) strength. The strength of the

Pozzutec 20 concrete when frozen after it had

attained the 3.4-MPa (500 psi) strength exceeded

that of the control by 1% (Fig. 5c).

Based on the data in Table B1 and in Figure 5, it

is clear that concrete made with Pozzutec 20 can

safely be frozen after it has achieved a compressive strength of 3.5 MPa (500 psi).

PHASE II: DEVELOPMENT

OF IMPROVED ADMIXTURE

Procedure

The objective of this phase was to develop a

new admixture that would outperform Pozzutec

20 in early strength gain at lower temperatures.

This work consisted of creating trial admixtures

composed of chemicals in aqueous solution. The

raw materials are proprietary information and

are not disclosed. Although no listing of individual chemicals is provided, the general categories of chemicals used are given: 1) inorganic salts,

2) organic chemicals containing hydroxy or

carboxy groups, and 3) organic surfactants (plasticizer). Phase II was divided into the three tasks

indicated in Table 10.

Task 1: Mortar screening

Task 1 used mortar as a rapid way to

screen the various chemicals. Using

mortar instead of concrete simplified

mixing operations by reducing material handling and permitting smaller

test specimens to be used. The performance of each trial admixture was

judged against two references: mortar

produced with 60 mL/kg (90 fl oz/

cwt) of Pozzutec 20, and plain mortar.

The mortars were cured at 10°C (50°F).

This temperature was used in the hope that it

would yield a reasonable indication of relative

admixture efficacy for lower temperatures. The

mix proportions are given in Table 11.

The mortar was prepared according to ASTM

C 109 in a Hobart mixer. Set times were obtained

with Gillmore needles at 10°C (50°F) ambient temperature. The mortars were tested at a 0.50 w/c

ratio so as to provide near-equal flow, or workability, for each mix. The water contents of the

mixtures were adjusted for water content of each

admixture. Compressive strengths were obtained

from 2-in. cubes cast after curing for one, three,

Table 10. Phase II tasks.

Task Description

1 Mortar screening

2 Concrete testing

3 Follow-up testing

Table 11. Phase II, Task 1; mortar mixture proportions.

Ingredient Amount

Type I cement, Blue Circle 500–550 gm (1.1–1.2 lb)

Concrete sand 1375–1513 gm (3.0–3.3 lb)

Tap water—16°C (60°F) 195–213 mL (6.6–7.2 fl oz) (admixture mortar)

225–242 mL (7.6–8.2 fl oz) (plain mortar)

Trial admixture 60 mL/kg (90 fl oz/cwt)

100 mL/kg (150 fl oz/cwt)

160 to 176 mL/kg (245 to 270 fl oz/cwt)

allow for elevating the concrete specimen temperature to 50°F) before being tested for compressive strength. Set time was determined according

to ASTM C 403, air content according to ASTM C

231 (pressure method [Type B]), and slump according to ASTM C 143 (penetrometer). The trial

admixtures were added to the mix water before

mixing started. Table 12 provides the mixture proportions used in this task.

Task 3: Follow-up testing

Task 3 consisted of follow-up work using the

better trial admixture systems found in Task 2.

11
The concrete was mixed at room temperature and

cured at –5 and –10°C (23 and 14°F). The best

admixtures were selected for further testing in

Phase III. The follow-up tests consisted primarily

of reexaminations and confirmation testing of the

better results.

Results and discussion

Task 1: Mortar screening

There is little to report in this task except to list

those admixtures that performed relatively well:

ARL-506, EX-3, EX-4, EX-5D, EY-1, EY-3, EY-7,

and EY-10. The results from all mortar screenings

are provided in Appendix C. Criteria such as set

time, both initial and final, compressive strength,

and admixture dosage were used in picking the

best performances.

Task 2: Concrete testing

Three trial admixtures were found

to perform well in concrete. The primary yardstick for admixture selection was compressive strength at

–10°C (14°F). The results from all

concrete testings are provided in

Appendix D. The admixtures chosen for further evaluation were ARL506, EX-4, and EY-11; ARL-506 is an

analog of Pozzutec 20.

Task 3: Follow-up testing

Task 3 further examined the three

best trial admixtures from Task 2. It

also examined two other groupings

of admixtures: two freeze-point depressants in combination with Pozzutec 20, and three new trial admixtures. The results are presented in

Tables 13–16. In all cases, the concrete was mixed at room temperature and cured at 20, –5, and –10°C

(70, 23, and 14°F).

Table 13 shows the results from

a reexamination of ARL-506 and

EX-4 in comparison to Pozzutec 20

and admixture-free concrete. All

mixtures had a cement factor of

365 kg/m3 (611 lb/yd3) and a w/c

of 0.48. At –5°C (23°F), the concrete made with high dosages of

ARL-506 and EX-4 gained 15 and

17%, respectively, more strength

than Pozzutec 20 at 28 days. At

–10°C (14°F), these admixtures produced concrete

that was significantly weaker compared with

Pozzutec 20 concrete cured at that same temperature. At room temperature neither of these two

trial admixtures provided as much strength as

that recorded for Pozzutec 20; the high doses of

ARL-506 and EX-4 gained 16 and 5%, respectively,

less strength than Pozzutec 20 at 28 days. Based

on the room temperature results, the ARL-506

and EX-4 were excluded from further consideration.

Table 14 shows the results of combining propylene glycol and urea, two freeze-point depressants not previously examined, with Pozzutec 20.

The purpose of doing this was to determine if

simply adding a freeze-point depressant to

Pozzutec 20 would enhance its low-temperature

Table 12. Phase II, Task 2; concrete mixture proportions. A Type I

cement with a 365-kg/m3 (611 lb/yd3) cement factor was used.

Ingredient Control Trial

Water/cement 0.463 0.438–0.440

Hugo sand, SG 2.58 24.5 kg (53.9 lb) 25.5 kg (56.2 lb)

Coarse agg, SG 2.84 36.4 kg (80.0 lb) 36.4 kg (80.0 lb)

Trial admixture none 60 mL/kg (90 fl oz/cwt)

none 100 mL/kg (150 fl oz/cwt)

Pozzutec 20 60 mL/kg (90 fl oz/cwt) none

Table 13. Strength results from two trial admixtures in concrete

with a 365-kg/m3 (611 lb/yd3) cement factor and a 0.48 w/c.

Admixture Curing

code name-dosage temperature Compressive strength—MPa (psi)

mL/kg (fl oz/cwt) (°C) 7 days 14 days 28 days

Control 20 28.3 (4102) 31.7 (4593) 34.2 (4960)

EX-4-60 (90) 20 27.2 (3947) 27.6 (4008) 30.1 (4371)

EX-4-100 (150) 20 29.4 (4258) 32.3 (4682) 35.0 (5079)

ARL-506-60 (90) 20 33.4 (4848) 36.0 (5225) 37.8 (5479)

ARL-506-100 (150) 20 33.2 (4810) 37.0 (5362) 39.6 (5748)

Pozzutec 20-100 (150) 20 35.4 (5140) 38.9 (5645) 41.6 (6036)

Control –5 1.1 (164) 1.2 (180) 1.8 (260)

EX-4-60 (90) –5 9.0 (1306) 11.4 (1649) 12.5 (1815)

EX-4-100 (150) –5 12.4 (1797) 16.2 (2348) 19.0 (2761)

ARL-506-60 (90) –5 8.3 (1202) 11.8 (1707) 13.7 (1985)

ARL-506-100 (150) –5 8.6 (1254) 13.5 (1964) 18.7 (2716)

Pozzutec 20-100 (150) –5 8.4 (1211) 12.1 (1752) 16.2 (2349)

Control –10 0.0 (0.0) 0.0 (0.0) 0.0 (0.0)

EX-4-60 (90) –10 3.4 (492) 3.4 (496) 3.9 (570)

EX-4-100 (150) –10 3.3 (482) 5.1 (738) 7.0 (1012)

ARL-506-60 (90) –10 1.8 (259) 2.2 (312) 2.8 (410)

ARL-506-100 (150) –10 1.4 (203) 2.9 (414) 4.2 (610)

Pozzutec 20-100 (150) –10 4.4 (645) 5.5 (799) 8.6 (1243)

12
capability without diminishing its room-temperature strength gain. All mixtures used a cement

factor of 420 kg/m3 (705 lb/yd3) and a w/c of 0.43.

At room temperature, the combination of 4.5% Pozzutec 20 plus 1.5%

propylene glycol provided the best

strength gain compared to the control mixture. It provided a 10%

strength gain over that of the control

mixture at 28 days, which, unfortunately, was less than the approximately 20% strength increase provided by just Pozzutec 20 in Phase I.

At –5°C (23°F), this same combination provided a 28-day strength

equal to 77% of the room temperature control mixture. This was better

than with Pozzutec 20 alone in Phase

I where it provided a –5°C (23°F)

strength equal to only 65% of the

room-temperature control mixture at

28 days. Since neither of these two

freeze-point depressants are routinely used by the concrete industry,

they were not considered further in

this CPAR project. However, it did

appear that the low-temperature

range of Pozzutec 20 could be extended by combining it with certain

chemicals.

Tables 15 and 16 show the results

of three trial admixtures coded EY11, EZ-3B, and EZ-4B. The Table 15

mixtures had a cement factor of 365

kg/m3 (611 lb/yd3) and a w/c of

0.48, while the Table 16 mixtures had

a cement factor of 420 kg/m3 (705

lb/yd3) and a w/c of 0.43. The Table

15 mixtures were tested at 60 and

100 mL/kg (90 and 150 fl oz/cwt),

while the Table 16 mixes were tested

at 100 mL/kg (150 fl oz/cwt) only.

At room temperature, all three admixtures provided about the same

strength results as those attained by

the control. They did not enhance

strength as much as did Pozzutec

20. Though it did not cause enhanced

strength at room temperature at the

dosage tested, the EY-11 provided

the highest 28-day strength at –5°C

(23°F) of all the admixtures tested.

(Note that such high dosages will

most likely not be used at room temperature.) Consequently, EY-11 was selected as

the admixture for continued study in Phase III.

Another admixture, EZ-3B, appeared to provide

Table 14. Strength results from Pozzutec 20 (P20) and propylene

glycol (PG) and urea with a 420-kg/m3 (705 lb/yd3) cement factor

and a 0.43 w/c.

Admixture

dosed by weight of

active ingredient per Curing

100 lbs of cement temperature Compressive strength—MPa (psi)

given in percent. (°C) 7 days 14 days 28 days

Control 20 32.2 (4668) 38.5 (5588) 42.1 (6104)

1.5% P20 + 4.5% PG 20 32.6 (4720) 40.0 (5800) 41.8 (6059)

3% P20 + 3% PG 20 35.1 (5088) 41.7 (6048) 44.6 (6470)

4.5% P20 + 1.5% PG 20 36.9 (5357) 42.2 (6126) 46.2 (6705)

1.5% P20 + 4.5% Urea 20 28.1 (4074) 34.9 (5065) 37.6 (5456)

Control –5 0.7 (101) 2.9 (415) 4.2 (606)

1.5% P20 + 4.5% PG –5 11.3 (1636) 22.1 (3206) 27.7 (4022)

3% P20 + 3% PG –5 14.4 (2089) 25.0 (3618) 28.5 (4131)

4.5% P20 + 1.5% PG –5 16.3 (2365) 27.0 (3908) 32.4 (4697)

1.5% P20 + 4.5% Urea –5 13.3 (1924) 22.2 (3226) 27.1 (3928)

Control –10 0.0 (0.0) 0.8 (111) 1.2 (177)

1.5% P20 + 4.5% PG –10 0.5 (78) 5.2 (751) 8.4 (1223)

3% P20 + 3% PG –10 1.7 (248) 5.9 (850) 11.6 (1677)

4.5% P20 + 1.5% PG –10 1.8 (260) 5.7 (825) 9.1 (1318)

1.5% P20 + 4.5% Urea –10 3.8 (552) 9.3 (1349) 12.9 (1866)

Table 15. Strength results from three trial admixtures in concrete

with a 365-kg/m3 (611 lb/yd3) cement factor and a 0.48 w/c.

Admixture Curing

code name-dosage temperature Compressive strength—MPa (psi)

mL/kg (fl oz/cwt) (°C) 7 days 14 days 28 days

Control 20 35.0 (5074) 40.3 (5843) 41.9 (6073)

EY-11 60 (90) 20 33.3 (5423) 37.4 (5423) 40.5 (5866)

EY-11 100 (150) 20 34.2 (4961) 39.1 (5663) 41.8 (6055)

EZ-3B 60 (90) 20 33.4 (4843) 38.3 (5555) 39.4 (5720)

EZ-3B 100 (150) 20 34.0 (4937) 38.0 (5503) 40.6 (5880)

EZ-4B 60 (90) 20 33.7 (4885) 38.9 (5644) 41.5 (6017)

EZ-4B 100 (150) 20 32.8 (4763) 36.9 (5352) 40.6 (5885)

Control –5 1.7 (245) 3.6 (521) 3.4 (499)

EY-11 60 (90) –5 20.2 (2928) 25.1 (3645) 26.5 (3848)

EY-11 100 (150) –5 24.8 (3598) 32.1 (4654) 35.5 (5154)

EZ-3B 60 (90) –5 19.1 (2768) 23.5 (3405) 24.9 (3607)

EZ-3B 100 (150) –5 23.1 (3348) 30.8 (4461) 33.2 (4819)

EZ-4B 60 (90) –5 19.5 (2829) 23.5 (3405) 23.8 (3452)

EZ-4B 100 (150) –5 24.4 (3687) 30.9 (4475) 34.6 (5022)

Control –10 0.0 (0.0) 0.8 (115) 1.0 (144)

EY-11 60 (90) –10 3.7 (540) 5.8 (842) 4.9 (714)

EY-11 100 (150) –10 5.3 (763) 8.6 (1242) 6.3 (909)

EZ-3B 60 (90) –10 3.8 (548) 6.0 (865) 5.6 (811)

EZ-3B 100 (150) –10 5.4 (790) 8.5 (1228) 7.4 (1078)

EZ-4B 60 (90) –10 4.2 (602) 6.4 (934) 6.2 (898)

EZ-4B 100 (150) –10 5.3 (773) 7.9 (1146) 6.9 (995)

13
somewhat higher strengths at –5°C (23°F) than

with EY-11, and could have been a prototype alternate for that reason, but it was discovered in

time to be relatively unstable (i.e., it tended to

precipitate out of solution) and was therefore

abandoned.

PHASE III: EVALUATION

OF IMPROVED ADMIXTURE

Procedure

The objective of Phase III was to more fully

evaluate the best Phase II admixture. Phase III

used all Phase I procedures except for one: the

critical strength test. Thus, Phase III consisted of

four experimental tasks (Table 17). The procedures used in this phase have been explained in

Phase I.

Results and discussion

Task 1: Strength vs. temperature

As was done in Phase I, the concrete was mixed

at room temperature and immediately after casting placed into 20, –5, and –10°C (70, 23, 14°F)

rooms for curing. Table 18 shows the strength

results for two cement factors. At room temperature, EY-11 provided concrete of essentially the

same strength as that of the control concrete.

Though the EY-11 did not enhance strength in the

way Pozzutec 20 is capable of, it did not interfere

with strength gain at room temperature, which

was an important consideration of this project. At

–5°C (23°F), EY-11 promoted strength that exceeded that of control concrete cured at 5°C (40°F).

Figure 6 illustrates this result. In that figure, the

5°C (40°F) reference strength was based on guidance given in ACI 1988. For the 365-kg/m3 (611

lb/yd3) cement factor, the EY-11 concrete exceeded

the ACI reference strength at all ages except for

28 days (Fig. 6a). However, this is not considered

a problem because the concrete has the potential

of recovering full strength when brought back

Table 16. Strength results from three trial admixtures in concrete

with a 420-kg/m3 (705 lb/yd3) cement factor and a 0.43 w/c.

Admixture Curing

code name-dosage temperature Compressive strength—MPa (psi)

mL/kg (fl oz/cwt) (°C) 7 days 14 days 28 days

Control 20 36.0 (5216) 38.4 (5573) 42.0 (6083)

EY-11 100 (150) 20 35.5 (5152) 37.8 (5474) 39.8 (5767)

EZ-3B 100 (150) 20 33.6 (4876) 35.7 (5182) 38.1 (5526)

EZ-4B 100 (150) 20 33.0 (4782) 35.5 (5145) 37.7 (5470)

Control –5 2.8 (410) 3.9 (562) 4.2 (607)

EY-11 100 (150) –5 24.0 (3478) 27.2 (3942) 30.5 (4423)

EZ-3B 100 (150) –5 24.1 (3494) 30.1 (4371) 33.8 (4895)

EZ-4B 100 (150) –5 21.8 (3160) 28.0 (4060) 28.4 (4117)

Control –10 0.4 (65) 0.9 (135) 0.9 (127)

EY-11 100 (150) –10 5.6 (806) 7.6 (1107) 8.7 (1263)

EZ-3B 100 (150) –10 6.7 (973) 8.0 (1160) 10.0 (1448)

EZ-4B 100 (150) –10 5.9 (861) 7.7 (1120) 8.1 (1168)

Table 17. Phase III tasks.

Task Description

1 Strength vs. temperature

2 Corrosion potential

3 Durability

4 Equivalent insulation

Table 18. Compressive strength, MPa (psi), of

the EY-11 mixtures. The 365-kg/m3 (611 lb/yd3)

cement factor had a w/c of 0.48 and the 420-kg/m3

(705 lb/yd3) cement factor had a w/c of 0.43. The

second number of the ID refers to EY-11 dosage.

Age—days

Mixture ID 7 14 28

2,0,20 30.5 (4423) 33.0 (4785) 38.4 (5572)

2,2,20 27.3 (3962) 31.4 (4550) 34.6 (5024)

2,3,20 27.5 (3988) 31.7 (4596) 34.0 (4933)

2,2,–5 14.4 (2086) 16.8 (2430) 18.9 (2745)

2,3,–5 16.6 (2406) 25.4 (3690) 27.6 (3998)

2,2,–10 4.8 (699) 5.6 (813) 6.7 (965)

2,3,–10 5.9 (852) 8.8 (1283) 10.6 (1538)

3,0,20 34.5 (5003) 37.4 (5429) 39.4 (5718)

3,2,20 30.7 (4456) 34.5 (4998) 37.8 (5479)

3,3,20 32.2 (4671) 36.6 (5307) 39.7 (5761)

3,2,–5 19.4 (2808) 22.4 (3246) 24.2 (3503)

3,3,–5 22.7 (3288) 27.6 (4005) 33.1 (4795)

3,2–10 6.1 (887) 6.7 (968) 7.8 (1130)

3,2,–10 7.5 (1081) 9.7 (1406) 11.3 (1638)

14
der and protruding from the top. The test area of

the rebar is limited to 30 cm2 (4.7 in2) by epoxy

paint. The specimens were cured for four days in

saturated calcium hydroxide solution to within

12.7 mm (0.5 in.) of the top surface. They were

then kept at a potential of +260 mV vs. a saturated

calomel electrode. The current flowing through a

1000-ohm resistor placed in the circuit is measured at regular intervals by voltage drop across

the resistor. If the current density is below 1 μA/

cm2, the admixture is considered not harmful.

Table 19 shows the results for Pozzutec 20 and

EY-11. Both admixtures provided results below 1

μA/cm2, indicating that neither admixture caused

corrosion at the dosages used.

One of the corrosion measuring methods used

in Phase I to measure the potential of Pozzutec 20

to initiate corrosion damage to embedded steel

rebar, the Lollipop Corrosion Test, was again used

to measure the potential of EY-11 to initiate corrosion. Two dosages of EY-11 were used (60 and

100 mL/kg [90 fl oz/cwt]), the result being compared in the same test with the same two dosages

of Pozzutec 20 and two references without admixture. The specimen size was 75- × 150-mm (3 ×

6 in.) cylinders, each concrete mix being prepared,

and the concrete specimens cured and otherwise

treated, in the same manner as were the earlier

lollipop examinations of Phase I, except that 15%

sodium chloride solution was used for ponding

in place of the 3% solution of Phase I; weekly

measurements were taken. Figure 7 shows that

EY-11 caused corrosion to be initiated at about

week 12 with the higher dosage (100 mL/kg, 150

fl oz/cwt) and around week 43 with the lower

dosage (60 mL/kg, 90 fl oz/cwt). Pozzutec 20, on

the other hand, was found to initiate corrosion at

earlier times, at about week 6 with the higher

dosage and week 23 with the lower, each dosage

causing initiation to occur earlier by about onehalf the time period. Two admixture-free reference specimens were shown to have initiated corrosion at weeks 39 and 43 for an average of 41

weeks for the two references. The trial admixture

EY-11, therefore, was found in this 75- × 150-mm

Relative Strength (%) 120

80

40

0 10 20 30

Age (days)

b.

a.

120

80

40

0

Control

(20 °C)

EY11

(– 5 °C)

ACI

(5 °C)

Figure 6. Strength gain of concrete made with

EY-11 cured at –5°C (23°F) compared to control concrete cured at two above-freezing temperatures. The line denoted as ACI (5°C) is

based on guidance provided by ACI (1988).

That line represents the minimum curing condition used by the construction industry today.

Figure 6a is for concrete containing a 365-kg/

m3 (611 lb/yd3) cement factor and a 100-mL/kg

(150 fl oz/cwt) EY-11 dosage. Figure 6b contains a 420-kg/m3 (705 lb/yd3) cement factor

and a 100-mL/kg (150 fl oz/cwt) EY-11 dosage.

Table 19. Harmlessness corrosion results.

Dosage Current

Admixture mL/kg (fl oz/cwt) μA/cm2

Pozzutec 20 30 (45) 0.539

Pozzutec 20 60 (90) 0.405

EY-11 50 (75) 0.724

EY-11 100 (150) 0.651

to warm conditions. The 100-mL/kg (150 fl oz/

cwt) dose with the 420-kg/m3 (705 lb/yd3) cement factor exceeded the ACI reference strength

at all ages (Fig. 6b).

Task 2: Corrosion potential

The potential of EY-11 to corrode steel reinforcement was tested according to the so-called

“Harmlessness Test” (modeled after a German

DIN standard according to discussions during

meetings of ASTM Committee G-1.14 1994–95).

The method employed in this project uses small

“lollipop” cylinder specimens measuring 50 × 100

mm (2 × 4 in.). The mortar used Type I cement, an

ASTM C 109 sand in a 1:3 cement:sand ratio and a

0.50 w/c. The embedded rebar is a No. 4 axially

located 25.4 mm (1 in.) off the bottom of the cylin15
test specimen not to have initiated corrosion with

the lower dosage of 60 mL/kg (90 fl oz/cwt), but

to have initiated corrosion at the higher dosage

level. Likewise, Pozzutec 20 was found to have

initiated corrosion, with the higher dosage causing damage earlier than the lower 60-mL/kg dosage.

Another similar test was run using the same

lollipop method, but this time with only 50- ×

100-mm (2 × 4 in.) cylinder specimens, to determine if specimen size mattered. The same dosage

levels of the two admixtures were repeated, as

were the two references. Figure 8 shows that the

two admixture-free references initiated corrosion

at Weeks 15 and 16, while EY-11 at the high and

low dosages initiated corrosion at 8 and 21 weeks,

respectively, and Pozzutec 20, again at the high

and low dosages, initiated corrosion at two and

ten weeks, respectively. Therefore, like the larger

cylinders, the lower dosage only (60 mL/kg, 90 fl

oz/cwt) of EY-11 did not cause corrosion initiation, and provided evidence that EY-11 was potentially less corrosive to steel rebar. The higher

EY-11 dosage (150 fl oz) initiated corrosion at an

even later time than the lower dosage (90 fl oz) of

Pozzutec 20. Also, as for the specimen size, the

smaller the test cylinder, the earlier the initiation

of corrosion. It is most important here to restate

that the admixtures Pozzutec 20 and EY-11 did

not cause corrosion to occur without chloride ions

800

600

400

200

0 4 8 12 16 20 24 28 32 36 40 44

Weeks

Potential (– mV vs. SCE)

Reference

EY-11

@ 60 mL/kg

Pozzutec 20

@ 100 mL/kg

Pozzutec 20

@ 60 mL/kg

EY-11

@ 100 mL/kg

Reference

Corr.

Line

Figure 7. Lollipop specimens, 75- × 150-mm (3 × 6 in.) cylinders ponded halfheight in sodium chloride solution.

Reference

EY-11

@ 60 mL/kg

Pozzutec 20

@ 100 mL/kg

Pozzutec 20

@ 60 mL/kg

Reference

Corr.

Line

800

600

400

200

Potential (– mV vs. SCE)

0 4 8 12 16 20 24 28 32 36

Weeks

EY-11

@ 100 mL/kg

Figure 8. Lollipop specimens, 50- × 100-mm (2 × 4 in.) cylinders ponded halfheight in sodium chloride solution.

16
present. It appears that the higher dosages of these

admixtures may decrease the chloride threshold.

Task 3: Durability

The freeze–thaw durability of concrete made

with Pozzutec 20 and EY-11 was tested using

ASTM C 666, Procedure A, and evaluated according to ASTM C 494. Table 20 shows the results. As

happened in Phase I, Pozzutec 20 passed the durability test at a dosage of 60 mL/kg (90 fl oz/

cwt) but not at 100 mL/kg (150 fl oz/cwt). EY-11,

on the other hand, showed very high durability at

both dosages.

Task 4: Equivalent insulation

The purpose of this task was to determine the

amount of insulation that EY-11 can replace in a

420 kg/m3 (705 lb/yd3) cement factor mix. Table

21 presents the strength results at various low

temperatures. Since EY-11 does not enhance the

late age strength of concrete (Phase III, Task 1)

when cured at room temperature, the effect of

EY-11 was evaluated only at the seven-day

strength. EY-11 was found to increase compressive strength relative to 10°C (50°F) down to approximately –1°C (30°F) for both dosages.

Table 22 shows that EY-11 is equivalent to a

thermal resistance of 1.1 m2 K/W (6.5 hr ft2 F/

Btu), or about 50 mm (2 in.) of fibrous glass insulation.

PHASE IV: FIELD APPLICATION

Procedure

The objective of Phase IV was to validate the

EY-11 admixture developed in Phase III by means

of a field trial. Special attention was given to workability, finishability, temperature records, and

strength development.

The prototype admixture (EY-11) was tested

outdoors at CRREL, Hanover, New Hampshire,

and at the Corps of Engineers Soo Locks, Sault

Ste. Marie, Michigan, during February and March

1994. The CRREL site was chosen because of its

proximity to testing facilities and because it provided a location convenient for long-term monitoring of the concrete. The Soo Locks was attractive because it provided an opportunity to

compare normal winter concreting to concreting

with antifreeze admixtures. The timing at each

site was determined from weather records and

forecasts that promised weather conditions appropriate to the –5°C (23°F) capability of the admixture. A technical representative from MB was

on hand to evaluate the effectiveness of the admixture with the cements used at each site. CRREL

personnel provided instrumentation for monitoring temperatures and helped measure properties

of the fresh and hardened concrete. Pozzutec 20

was used to batch a separate mix of concrete for

comparison purposes.

Table 20. Durability factors for Pozzutec 20 and

EY-11 concrete.

Dosage

60 (90) 100 (150)

Admixture None mL/kg (fl oz/cwt) mL/kg (fl oz/cwt)

Control 99

Pozzutec 20 99 Failed

EY-11 98 96

Table 21. Equivalent insulation test results.

Compressive strength—MPa (psi)

Mixture ID 7 days 14 days 28 days

3,0,10 (control) 27.9 (4052) 39.8 (5767) 43.8 (6348)

3,2,5 32.4 (4691) 36.7 (5326) 39.8 (5771)

3,2,2 30.6 (4439) 32.3 (4685) 35.3 (5112)

3,2,–2 26.5 (3846) 35.7 (5170) 38.2 (5543)

3,3,5 33.0 (4778) 36.9 (5349) 42.1 (6098)

3,3,2 30.8 (4465) 34.1 (4941) 35.8 (5190)

3,3,–2 26.3 (3817) 34.3 (4970) 38.8 (5628)

Table 22. Equivalent insulation values for 152-mm- (6 in.)

thick wall maintained at 10°C (50°F) for seven days.

Air temperature Required thermal resistance Equivalent fibrous

Mixture °C (°F) m2 K/W (hr ft2 F/Btu) glass—mm (in.)

3,2 –1 (30.2) 1.1 (6.5) 50 (2.0)

3,3 –1 (30.2) 1.1 (6.5) 50 (2.0)

17
Results and discussion

New Hampshire

Test site. At CRREL, a composting bin consisting of a 16.5-cm- (6.5 in.) thick reinforced slab on

grade 3.7 m wide by 4.6 m long (12 × 15 ft) with

1.2-m- (4 ft) high reinforced 203-mm- (8 in.) thick

walls on three sides was cast during 17 and 18

February. The bin was oriented such that the long

axis of the slab ran east–west, and the three walls

formed the east, south, and west sides of the bin.

The north wall was omitted. The bin was divided

into five sections, three wall sections and two slab

sections. Dividing the bin in this manner allowed

for five admixtures to be evaluated. This report

discusses the two admixtures provided by Master Builders: Pozzutec 20 and EY-11.

Site preparation consisted of removing a meter

of snow from the ground, placing about 100 mm

(4 in.) of dry sand on the newly exposed frozen

ground, and setting the forms and reinforcing

steel on the sand. The concrete was placed in the

forms, consolidated, and finished as usual. A plastic sheet was placed over the slab and over the

top of the wall for three days to minimize water

loss. The wooden forms were removed from the

walls 20 hours after the concrete was placed. No

thermal protection was provided to the concrete.

Plastic pullout cylinders, 100 × 150 mm (4 × 6 in.),

were cast into the slab and the top of the wall to

provide in-situ strength gain results. No control

concrete was cast at the site during this study.

Workability/finishability. The initial slump of the

EY-11 mix as delivered to the site was poor. The

original concern was that the 6% dosage (Table

23) of EY-11 was causing the cement to set up too

rapidly but, as explained later, a low water and

plasticizer content contributed to this low slump.

The Pozzutec 20 mix used for the west half of the

slab had good workability, although the concrete

workers complained that the concrete seemed to

tear when finished with a trowel. There was no

apparent reason for this problem as ice was not

forming on the bottom of the trowels despite the

cold weather. The high slump, as discussed later,

may have contributed to this finishing problem.

The EY-11 was placed in the west wall and in the

west third of the south wall, so finishing characteristics could not be evaluated for this admixture.

Table 23 gives the proportions of the two concrete mixtures used in this study. Table 24 gives

the properties of fresh concrete. As previously

described, Pozzutec 20 was used in the slab and

EY-11 in the wall. The 4% dosage of Pozzutec 20

is equivalent to 60 mL/kg (90 fl oz/cwt) used

elsewhere in this report. Likewise, the 6% EY-11

equates to 95 mL/kg (145 fl oz/cwt).

The target water-to-cement ratio was 0.44 with

a slump of 100 mm (4 in.). The Pozzutec 20 and

EY-11 mixes differed from this target, especially

in w/c. The water content of the Pozzutec 20 mix

was intentionally reduced below the target value

at the mix plant because Pozzutec 20 contains a

high-range water reducer and the mix plant normally adds a plasticizer to this mixture. The 0.39

w/c resulted in a relatively high slump of 210

mm (8.25 in.) (Table 24). Based on this result, and

because EY-11 also contained a high-range water

reducer, the water content of the EY-11 mixture

was held to 0.40 at the mix plant. Also, the mix

plant was requested not to add plasticizer. The

EY-11 concrete unexpectedly arrived at the site

with no measurable slump. Thus, water was carefully added to the mix until the concrete in the

truck was noticeably looser. The extra water produced slump of 127 mm (5 in.) (Table 24) and a

0.55 w/c (Table 23). The resulting mix was easy to

place and consolidate within the wall forms. Note

that the concrete temperatures of both placements

were above freezing, not the more desirable below freezing.

Thermal record. Five thermocouples were

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)

 no. kg/m (lb/yd3) 3 kg/m3 (lb/yd3) kg/m (lb/yd3) 3 ratio mL/m3 (fl oz/yd3) mL/m3 (fl oz/yd3) (%)

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
Table 24. Properties of fresh concrete.

Slump Air Unit wgt Concrete

Mix mm (in.) (%) kg/m3(lb/ft3) °C (°F)

P20 210 (8.25) 4.4 2389 (149) 10 (50)

EY-11 127 (5.00) 4.0 2357 (147) 16 (61)

Table 25. Concrete placement time.

Mix Date Start

P20 17 Feb 12:30 p.m.

EY-11 18 Feb 12:05 p.m.

15

10

5

0

– 5

– 10

– 15

– 20

0 5 10 15 20 25

Time (days)

Air Temperature (°C)

Figure 9. Air temperatures from 7:30 a.m., 17 Feb, through

12:30 a.m., 10 Mar 1994, at Hanover, New Hampshire.

slab and six through the wall beginning at one

surface and ending at the other. An additional

thermocouple was positioned away from the concrete out of direct sunlight to record ambient air

temperature. A malfunction of the data recorder

eliminated some temperature recordings from

portions of days two through five. Some thermocouple locations were unable to be read at all due

to apparent problems with the sensors themselves.

Figures 9–11 provide the recorded temperature histories. Table 25 gives the approximate

times when each concrete was placed. The air

temperature (Fig. 9) averaged –1.4°C (29.5°F) over

the first five days, with a high of 10°C (50°F) and

a low of –16°C (–3.2°F), while the concrete averaged 2.2°C (36.0°F) over that same period. The air

temperature on the 17th (day 1) began at –16°C

(–3.2°F) at 7:30 a.m., rose to a high of 4.5°C (40.1°F)

at 2 p.m., and then dropped off to well below

freezing that night. The slab concrete (with

Pozzutec 20) temperature (Fig. 10) at placement

(12:30 p.m.) was 10°C (50°F). It cooled to about

4.8 cm

Below Top Surface

Bottom

of Slab

9.5 cm

above Base

15

10

5

0

– 5

– 10

0 5 10 15 20 25

Time (days)

Temperature (°C)

Figure 10. Temperature history of the Pozzutec 20 concrete slab placed on grade at

Hanover, New Hampshire. The slab was placed at 12:30 p.m. on 17 Feb (day 1). A

malfunction of the data recorder eliminated temperatures from portions of day 2

through day 5.

19
3°C (37°F) when it came in contact with the cold

ground but quickly rose to 13.2 °C (55.8°F) by 1:00

p.m. and then began to cool. A malfunction of the

temperature recorder prevented recordings from

18 Feb at 12:30 a.m. to 21 Feb at 4:30 p.m. Although the air temperature during the first three

nights got quite cold, –15 °C (5°F) at 6:30 a.m. on

the 18th (day 2), –10.3°C (13.5°F) at 6 a.m. on the

19th (day 3), and –5.4°C (22.3°F) at 2 a.m. on the

20th (day 4), the concrete did not freeze. A petrographic examination of core samples drilled from

the concrete confirmed this. Data from a separate

project show that a slab placed next to this slab at

9 a.m. on the same day dropped to a low of only

–1.2°C (29.8°F) on 19 Feb (day 3). This kind of

temperature would not have damaged the

Pozzutec 20 slab. The Pozzutec 20 slab cooled to

below –5°C (23°F) at 3 a.m. on the 26th (day 10),

and remained below that temperature until 7 a.m.

on 2 March, a five-day period. It then rose slowly

the next seven days to near 0°C (32°F) on 10 March.

Notice that the slab was close to uniform temperature throughout the recording period. The

three temperature recordings (two other thermocouples malfunctioned) nearly overlay one another. Because of the closeness of the recorded

temperatures, no attempt was made to distinguish

the significance of one line from another.

The wall with admixture EY-11 was placed on

18 Feb (day 2) at 12:05 p.m. at a concrete temperature of 16°C (61°F). Unfortunately, the recorder

malfunction prevented any temperature record

until 21 Feb (day 4) at 4:30 p.m. Two temperature

histories, one on the surface and one internal temperature, are plotted in Figure 11. A petrographic

examination of core samples obtained in May

shows that the wall did not suffer frost damage.

This was not a severe test of the low-temperature capability of either admixture because the

ambient and concrete temperatures both were

above freezing.

Strength. Results of the strength tests from the

field-cured pullout cylinders taken from each concrete section are presented in Table 26. Though

no control concrete was cast at the site for direct

comparison to the pullout cylinder strength results, the strength of admixture-free concrete of

similar mix design with a 0.44 w/c ratio cured at

room temperature is given. As can be seen, the

field samples exceeded the 28-day strength of the

room-cured concrete. This is remarkable for the

EY-11 owing to its relatively high w/c of 0.55.

Michigan

Test site. The second field test was conducted

in northern Michigan in March 1994. The Corps‘

Soo Area Office had scheduled 39 sections of concrete to be replaced because of their advanced

stage of freeze–thaw deterioration. The work area

was located on the southwest pier, which borders

the ship canal of the Poe Lock, the largest of four

locks operated and maintained by the Corps of

Engineers, Sault Ste. Marie, Michigan. Inspection

10

0

– 10

– 200 5 10 25

Time (days)

Temperature (°C)

15 20

8.1 cm (3.2”) into Wall

Surface

Figure 11. Temperature history of the EY-11 concrete wall placed at 12:05

p.m. on 18 Feb (day 2) at Hanover, New Hampshire. A malfunction of the

data recorder eliminated temperature records until 21 Feb (day 5).

Table 26. Strength results, MPa (psi), from pullout cylinders cast into the concrete.

Mixture 7 days 28 days

Pozzutec 20 27.4 (3975) 48.3 (7010)

EY-11 20.3 (2949) 38.1 (5526)

Room-cured admixture-free 30.9 (4480) 37.6 (5451)

20
and repair of the locks themselves is normally

done during the winter months, January through

March, when shipping is stopped. Other repair

work, such as the replacement of the slabs described here, is also most conveniently done during the winter nonshipping season, making this

test particularly relevant.

For this test, four reinforced slabs on grade

were selected for testing two admixtures. Each

slab measured 5.5 m wide by 6.1 m long by 150

mm thick (18 × 20 ft × 6 in.). The two admixtures

tested were EY-11 and Pozzutec 20. The EY-11

admixture was used in two dosages: low and high,

designated EY11L and EY11H. The Pozzutec 20

admixture was used in a single dosage. The four

test slabs were cast between 15 and 16 March.

Site preparation consisted of jackhammering

out alternate sections of concrete, replacing 150

mm (6 in.) of base material with an equal amount

of coarse crushed stone, and setting forms and

reinforcing steel. The slabs that remained between

the removed sections provided work space for

finishing operations. A temporary heated enclosure was erected over one slab to serve as a control section and to provide a comparison between

normal and antifreeze concrete operations. A second enclosure, unheated, was used to cover the

EY11L admixture section as a secondary test. Admixture-free concrete was placed in the heated

shelter while concretes made with the EY11H and

Pozzutec 20 admixtures were placed in sections

exposed to ambient air outside the shelter.

The concrete was placed and finished in the

normal fashion. Except for the heated control section, the concrete remained thermally unprotected.

A plastic sheet was placed over the two exposed

concrete sections for seven days to minimize water loss. The concrete in the two shelters was left

uncovered. Thermocouples connected to data loggers monitored concrete and air temperatures.

Numerous 75- × 150-mm (3 × 6 in.) cylindrical

samples were cast from each concrete section and

stored in two locations next to the slabs on grade

and overhead in the heated enclosure. A concrete

testing laboratory in northern Michigan tested the

cylinders for compressive strength at regular intervals.

The concrete was transported by rotary-drum

truck from a ready-mix plant 8 km (5 mi) 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 27. Table 28 gives the concrete

placement times. The concrete was delivered 30

to 45 minutes after water was added to the mix,

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

to 60 minutes. Table 29 gives the properties of the

fresh concrete.

Workability/finishability. 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 inTable 27. Mix proportions.

3/4 in. Admixture dosage

maximum size Cement (wgt active ingredient

coarse aggregate Sand (Type IA portland) w/c per cement wgt)

Mix kg/m3 (lb/yd3) kg/m3 (lb/yd3) kg/m3 (lb/yd3) ratio (%)

Control 1047 (1760) 774 (1300) 392 (658) 0.41 None

EY11L 1047 (1760) 774 (1300) 392 (658) 0.41 3.7

EY11H 1047 (1760) 774 (1300) 392 (658) 0.38 6.3

Pozzutec 20 1047 (1760) 774 (1300) 392 (658) 0.39 4.0

Table 28. Concrete placement time.

Mix Date Start

Control 15 March 11:00 a.m.

EY11L 16 March 9:45 a.m.

EY11H 16 March 11:40 a.m.

Pozzutec 20 16 March 1:27 p.m.

Table 29. Properties of fresh concrete.

Slump Air Unit wgt Temperature

Mix mm (in.) (%) kg/m3 (lb/ft3) °C (°F)

Control 51 (2) 3.2 2307 (144) 12.2 (54)

EY11L 140 (5.5) 3.2 2307 (144) 3.3 (38)

EY11H 140 (5.5) 4.7 2275 (142) 3.3 (38)

Pozzutec 20 150 (6) 3.4 2330 (145) 4.4 (40)

21
side the heated shelter. The workers found the

freedom of movement better outdoors than in a

temporary enclosure, while the heated shelter was

useful as a warming hut between concrete deliveries. The workers remained outdoors for periods

of approximately two hours. The Pozzutec 20 and

EY-11 concretes were very easy to place,

consolidate, and finish, according to the concrete workers. The concrete maintained its

workability throughout the finishing operation, which lasted nearly two hours after water was first added to the mixtures at

the mix plant. According to workers’ comments, the EY-11 mixture seemed to be

somewhat easier to finish compared to the

Pozzutec 20 or the control, though no difficulty was noted with working with any of

the mixtures.

Thermal record. Thermocouples connected

to data loggers monitored concrete and air

temperatures. Five thermocouples were

equally spaced throughout the thickness of

each slab, beginning at the top surface. (The

temperature of the Pozzutec 20 was not recorded due to equipment malfunction.) An

additional thermocouple was positioned

away from the concrete, 150 mm (6 in.)

above grade and out of direct sunlight, to

record the ambient 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 cold gravel.

Figures 12–14 show the temperatures of the

slabs’ top surfaces and the temperature of

surrounding ambient air. The recording

period for each concrete section began at

the time shown in Table 28 and extends

through midnight, 22 March.

Figure 12 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 (20°F) by the time concreting started, but after the walls were replaced, the shelter warmed up again. However, the shelter temperature fluctuated

daily. The maximum of 29.7°C (85°F) occurred at

4:10 p.m. on the 16th, and two lows of –0.2°C

(31°F) and 0.4°C (33°F) 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

Temperature (°C)

Time (days)

30

20

10

0

– 10

March ‘94

15 16 17 18 19 20 21 22 23

Air

Control

Temperature (°C)

March ‘94

Time (days)

10

5

0

– 5

– 10

– 15

15 16 17 18 19 20 21 22 23

Air

EY11L

Figure 12. Temperature history of the top surface of the control slab and the heated air in the control shelter at Sault Ste.

Marie, Michigan.

Figure 13. Temperature history of the top surface of the EY11L

slab and that of the outdoor air at Sault Ste. Marie, Michigan.

Figure 14. Temperature history of the top surface of the EY11H

slab and that of the outdoor air at Sault Ste. Marie, Michigan.

20

10

0

– 10

– 20

15 16 17 18 19 20 21 22 23

Air

EY11H

Temperature (°C)

Time (days)

March ‘94

22
turned off about 4 p.m. on 22 March. The

average air temperature in the shelter for the

recording period was 10.5°C (51°F).

The control concrete was delivered to the

site in two separate shipments, at a temperature of about 12°C (54°F) 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 to

1.3°C (34°F) (Fig. 8). 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 (54°F). The concrete continued to warm until it reached 20.3°C (68.5°F)

at 7 a.m., 16 March, in spite of the air cooling

to 9.4°C (48.9°F). Like the air, the concrete

temperature fluctuated throughout the recording

period. It reached a maximum temperature of

25.3°C (77.5°F) at 4:10 p.m. on the 16th and a

minimum of 3.8°C (38.8°F) 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 (55.9°F). It never dropped below 0°C during this period.

The EY-11 mixtures were placed on 16 March,

the colder of the two days during which concrete

was placed. The outdoor air temperature, shown

in Figure 13 and again in 14, averaged a chilly

–8.7°C (16.3°F) through midnight on the 16th,

though it rose to slightly above freezing for a

short time by midday, the 17th. The minimum

outdoor air temperature of –16.5°C (2.3°F) was

recorded at 6:45 a.m. on 17 March. Winds created

wind chills down to –28°C (–18.4°F) during the

17th. Thereafter the outdoor air temperature became much milder. The average outdoor air temperature from 16 March through 22 March was

–2.4°C (27.7°F).

Figure 13 shows the temperatures of the EY11L

concrete and the air inside the unheated shelter.

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

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

(37.9°F). As was done with the control section,

two walls of the unheated shelter were removed

temporarily. When exposed to the –10°C (14°F)

(but warming) air, the concrete temperature

quickly dropped from its delivered temperature

to 2°C (35.6°F), but almost immediately began

rising, reaching 4.3°C (39.7°F) by 4 p.m. After that

the concrete temperature dropped to –3°C (26.6°F),

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

around –3°C (26.6°F). Its average temperature was

0.9°C (33.6°F) through 4 p.m. on 22 March.

Figure 14 shows the temperatures of the EY11H

concrete and the outdoor air. The freezing point

of this concrete was –5°C (23°F). The EY11H mix

was cast outdoors at 11:40 a.m. on 16 March. It,

too, began at 3.3°C (37.9°F). Instead of cooling

when exposed to the –7.3°C (18.9°F) air, however,

it warmed to 11.8°C (53.2°F) at 2:10 p.m. before

dropping to –4.4°C (24.1°F) at 7 a.m. on 17 March.

It reached its lowest temperature of –5.5°C

(22.1°F) at 7 a.m. on 20 March, four days after

being cast. Its average temperature was 2.4°C

(36.3°F) through 4 p.m. on 22 March.

Figure 15 shows the temperatures of an EY11L

cylinder stored on grade in the unheated shelter.

The cylinder’s temperature dipped below –5°C

(23°F) on several occasions, the first at 8:00 p.m.

on 16 March, about ten hours after it was cast.

The average temperature of the cylinder through

4 p.m. on 22 March was –1.3°C (29.7°F).

Strength development. Several 75- × 150-mm (3 ×

6 in.) cylindrical samples were cast from each

type of concrete and stored in two locations on

grade next to the slabs and overhead in the heated

enclosure. A concrete testing laboratory in Michigan periodically tested the cylinders’ compressive strength.

The compressive strengths of the cylinders cannot be used as an indicator of the in-place strength

of the antifreeze concrete because, as Figure 15

shows, the cylinders probably froze. Subsequent

petrographic analysis of the suspected frozen cylinders at CRREL revealed typical ice lens patterns in the cylinders. Strengths reported by the

testing laboratory indicate that the cylinders deTemperature (°C)

Time (days)

March ‘94

10

5

0

– 5

– 10

– 15

Cylinder

15 16 17 18 19 20 21 22 23

Figure 15. Temperature history of the center of mass of a 75- ×

150-mm (3 × 6 in.) cylinder of EY11L concrete stored on grade

in the unheated shelter at Sault Ste. Marie, Michigan.

23
veloped only about half their potential strength,

which is indicative of concrete that has frozen

while curing.

Likewise, the strengths of the cylinders stored

on an overhead shelf 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

(Table 30). The cores showed that the antifreeze

concrete was stronger than the control concrete in

compression. None of the slabs showed signs of

frost damage.

Cost comparison between conventional and antifreeze concrete. As previously mentioned, a heated

shelter was used for the control concrete. This

provided an opportunity to compare costs between normal winter concreting and concreting

with antifreeze admixtures. Based on these field

tests it became apparent that the main difference

between normal concrete and antifreeze concrete

is the heat, shelter, and labor needed to protect

normal concrete compared to the chemicals

needed to protect antifreeze concrete. The cost to

erect, heat, and dismantle the temporary shelter

at the Soo Locks was estimated to be $1,079.54

(Table 31). Heating accounted for close to 15 percent of this expense. Since antifreeze admixtures

are still prototypes, their market price has not

been determined. However, based on the estimate developed for the shelter, the cost of an

antifreeze could potentially be as high as $21 per

gallon.

Summary of both field tests. The New Hampshire

field demonstration was not considered to be a

severe enough test of the low-temperature capability of EY-11. The concrete did not freeze until it

had gained considerable strength. However, this

test showed that no special skills are needed to

work with the prototype admixture at nearfreezing conditions.

The northern Michigan field demonstration

provided a good evaluation of EY-11 under severe conditions. Normal unprotected concrete

would have frozen during this test. The freezing point depression and accelerated cure properties of the EY-11 concrete enabled it 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 four

months after construction and examined under a

microscope showed no signs of frost damage.

The drilled cores were also tested for compressive strength, thereby providing 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. The

concern was 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 EY-11 concrete 21

hours after placement was about –1.2°C (30°F),

and for the high-dosage EY-11 concrete four days

after placement, it was –2.6°C (27.3°F ). At these

Table 30. Test results from 92- × 133-mm (4 × 5.25 in.)

core samples drilled in July 1994. Densities are based

on cylinder dimensions and mass. Minimum design

strength was 32 MPa (4640 psi).

Compressive strength Bulk density Evidence of

Mix MPa (psi) kg/m3 (lb/ft3) past ice?

Control 46.7 (6770) 2310 (143.7)) No

EY11L 50.6 (7350) 2320 (144.4) No

EY11H 53.2 (7720) 2290 (142.5) No

Pozzutec 20 54.1 (7840) 2340 (145.6) No

Table 31. Winter cost estimate.

Shelter

Erect shelter

(6 men, 1/2 day @ $23/hr) $552.00

Heat shelter - 1 d prior to pour and 7 d after

(8 d @ 21.4 gal propane/d @ $0.78/gal) $133.54

Dismantle shelter $276.00

Materials—assume 9 reuses

(Total cost estimated at $1,062) $118.00

Total estimated cost of shelter $1,079.54

Antifreeze admixture

Volume of concrete placed inside shelter 6.7 yd3

Dosage of admixture per 100 lb of cement 150 fl oz

Amount of cement per yd3 of concrete 658 lbs

Amount of admixture per 6.7 yd3 of concrete 51.67 gal

Cost of admixture to equal cost of shelter 20.89/gal

24
temperatures and by these times, even admixture-free concrete may have been able

to set and become resistant to freezing.

The test showed that a plastic sheet was

capable of providing more than just protection against moisture loss. Figures 13 and

14 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

days but 21 March, which was cloudy. On

that day, the two concrete temperatures

were nearly identical. During nighttime, 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 within 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 six-day temperature of the concrete under the plastic sheet averaged 2.4°C (36.3°F) compared to only 0.9°C (33°F) 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 Locks stated 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

(–4°F), possibly lower, provided a heated shelter

was available to warm up in periodically. At the

Soo, the workers worked outdoors in windy

–10°C (14°F) weather for two-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 suspected.

Concreting in winter costs more than during

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

were 113 percent for the enclosure, and up to 43

percent 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.

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

concrete at –5°C (23°F) instead of at the current

limit of 5°C (41°F) can be determined by looking

at weather records. The number of days that the

maximum air temperature in northern Michigan

(at the Soo Locks) exceeded various low temperatures is shown in Figure 16. As can be seen, pushing the temperature envelope to –5°C (23°F) 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 United

States.

CONCLUSIONS

The results from investigating Pozzutec 20 and

developing a new prototype admixture indicate

the following:

1. Pozzutec 20 accelerates and enhances the

strength gain of concrete. When cured at room

temperature, Pozzutec 20, used at its maximum

permissible dosage of 60 mL/kg (90 fl oz/cwt),

improved the seven-day strength of concrete by

nearly 20%. A similar result was produced when

the concrete was tested after 56 days of roomtemperature curing.

2. Compared to the more-than 35 trial admixtures tested, Pozzutec 20 provided the fastest setting concrete. In one test conducted in mortar,

Pozzutec 20 shortened the initial set time of concrete from 4 1/6 hours to 2 5/6 hours. The best

Figure 16. Possible extension of construction season with various low-temperature limits (Horrigan 1995, unpublished). Time (days)

400

300

0 5 0 – 5 –10 – 20

200

100

Lowest Working Temperature (°C)

25
trial admixture produced a set time that was 20

min longer than that achieved with the Pozzutec

20 admixture. Other admixtures acted as set retarders, producing concrete set times in excess of

those produced by admixture-free concrete. These

comparisons were drawn from mortar cured at

room temperature and made with 365 kg/m3 (611

lb/yd3) of Type I cement.

3. Pozzutec 20 did not contribute to the corrosion of reinforcing steel embedded in concrete

submerged in sodium chloride solution. This was

true for both the 60- and 100-mL/kg (90 and 150 fl

oz/cwt) dosage.

4. At its maximum permissible dosage of 60

mL/kg (90 fl oz/cwt), Pozzutec 20 did not reduce

the freeze–thaw durability of standard concrete

beams tested according to ASTM C 666, Procedure A. At that dosage, the durability factor of

concrete made with Pozzutec 20 following 300

cycles of freezing and thawing was 99 compared

to control concrete, which was also 99. A durability factor of 80 is considered passing. At a dosage

of 100 mL/kg (150 fl oz/cwt), the durability factor of the concrete dipped below 80 after 204 cycles

of freezing and thawing.

5. Pozzutec 20 at a dosage of 60 mL/kg (90 fl

oz/cwt) was determined to be equivalent to placing 50 mm (2 in.) of fibrous glass insulation over

the concrete. This is the thickness of insulation

that admixture-free concrete would require to remain above freezing for seven days at an air temperature very near freezing.

6. The critical freezing strength of concrete

made with Pozzutec 20 is considered the same for

admixture-free concrete. Pozzutec 20 does not

adversely affect the strength at which concrete

can first be frozen.

7. When used at its maximum permissible dosage of 60 mL/kg (90 fl oz/cwt), Pozzutec 20 was

unable to promote strength in concrete cured at

–5°C (23°F) at the same rate as that in admixturefree concrete cured at 5°C (41°F). This finding

prompted the search for an improved low-temperature admixture.

8. The prototype admixture, code named EY11, was selected as the potential improvement to

Pozzutec 20 for use in freezing temperatures.

9. EY-11 at a dosage of 100 mL/kg (150 fl oz/

cwt) was able to promote strength in concrete

cured at –5°C (23°F) at the same rate as that developed in admixture-free concrete cured at 5°C

(23°F). This is considered a major advantage over

existing admixtures used by the concrete industry today.

10. At the 100-mL/kg (150 fl oz/cwt) dosage,

the EY-11 admixture produced a concrete that

easily passed the ASTM C 666, Procedure A,

freeze–thaw test. The EY-11 concrete had a durability factor of 96 at the end of 300 cycles of freezing and thawing compared to a durability factor

of 99 for admixture-free concrete.

11. At dosages of 60 and 100 mL/kg (90 and

150 fl oz/cwt), EY-11 was not found to contribute

to corrosion of steel reinforcing embedded in concrete submerged in calcium chloride solution.

12. EY-11 was determined to be equivalent to

55.9 mm (2.2 in.) of insulation when the ambient

temperature is as low as –1°C (30°F).

13. The negative aspect of the EY-11 admixture

is that it did not promote short set times as effectively as did Pozzutec 20. The set time of EY-11

was approximately half an hour longer than that

with Pozzutec 20. Also, the EY-11 admixture did

not promote enhanced strengths to the same degree as did Pozzutec 20 when concrete was cured

at room temperature. These are considered important productivity factors.

14. The field tests clearly demonstrated that

working with EY-11 required no new skills. The

concrete was easily mixed at low temperature,

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. Because external heat

was not needed to protect the concrete, a tremendous amount of thermal energy was conserved.

The resulting concrete quality was excellent.

15. The potential effect of being able to place

concrete at temperatures below freezing is significant. Pushing the winter concreting envelope

from the current 5–10°C limit to –5°C (23°F) can

extend the “normal” construction season by over

two months in northern Michigan, such as at the

Soo Locks. Since the climate at the Soo is similar

to that of the coldest areas in the conterminous

United States, the construction season should be

extendible by at least two months in the United

States by using an admixture with the low-temperature capability of the experimental admixture EY-11.

26
RECOMMENDATIONS

A new low-temperature concreting technology

was explored with the result that a prototype

freezing-temperature-protection admixture has

been developed. The resulting EY-11 prototype

affords superior low-temperature protection compared to existing admixtures and provides good

freeze–thaw durability at high dosages. These are

important qualities. However, EY-11 needs further development to improve its ability to accelerate setting and enhance strength at above-freezing temperatures in order to fit into current ASTM

(C 494) testing guidelines for concrete admixtures.

It is believed necessary and in the best interests of

Master Builders to develop an admixture that performs well at both above- and below-freezing temperatures. Consequently, MB has chosen not to

market EY-11 until improvements can be made,

particularly those of setting and early strength, at

temperatures above freezing.

LITERATURE CITED

ACI (1988) Cold Weather Concreting. ACI 306-88.

Detroit, Michigan: American Concrete Institute.

Aguilar, A., A.A. Sagues, and R.G. Powers (1990)

Corrosion measurements of reinforcing steel in

partially submerged concrete slabs. In Corrosion

Rates of Steel in Concrete (N.S. Berke, V. Chalker,

and D. Whiting, Eds.), ASTM STP 1065. Philadelphia, Pennsylvania: American Society of Testing

and Materials, p. 66–85.

ASTM Committee G-1.14 (1995) Corrosion of Reinforcing Steel: Discussions. Philadelphia, Pennsylvania: American Society of Testing and Materials.

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

Dawson, J.L. and P.E. Langford (1988) The electrochemistry of steel corrosion in concrete compared to its response in pore solution. In The Use

of Synthetic Environments for Corrosion Testing

(P.S. Francis and T.S. Lee, Eds.), ASTM STP 970.

American Society of Testing and Materials, p.

264–273.

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

Serbin (1974) Thermal behavior of concrete slab

on frozen ground bed. In The Second International

Symposium on Winter Concreting, Vol. 1. Moscow:

Stroyizdat, p. 23–33. Available as CRREL Draft

Translation 729.

Horrigan, T. (1995) Unpublished chart, Research

and Engineering Directorate, CRREL, Hanover,

New Hampshire.

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

cold weather concreting: A literature review. USA

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

Nmai, C.K., M.A. Bury, and H. Farzam (1994)

Corrosion evaluation of a sodium thiocyanatebased admixture. Concrete International, April.

Sagues, A.A. (1987) Corrosion measurements of

reinforcing steel in concrete exposed to various

aqueous environments. In Corrosion of Metals in

Concrete, Proceedings of the CORROSION/87 Symposium on Corrosion of Metals in Concrete, University of South Florida. NACE Unit Committee T3K, p. 13–24.

Tourney, P. and N. Berke (1993) A call for standardized tests for corrosion inhibitors. Concrete

International, 15: 57–62.

27
APPENDIX A: PHASE I, TASK 1 STRENGTHS

Table A1. Compressive strength, MPa (psi), with Type I cement

and a 365-kg/m3 (611 lb/yd3) cement factor.

Age—days

Mixture ID 7 14 28 56

2,0,20 30.2 (4385) 33.8 (4898) 33.9 (4916) 34.9 (5057)

2,1,20 31.9 (4621) 33.7 (4881) 36.3 (5258) 37.6 (5447)

2,2,20 35.3 (5116) 37.8 (5484) 39.9 (5788) 41.1 (5965)

2,3,20 35.4 (5140) 38.9 (5645) 41.6 (6036) 45.2 (6557)

2,0,5 25.1 (3636) 29.2 (4239) 33.2 (4810) 39.5 (5725)

2,1,5 25.1 (3640) 28.8 (4183) 33.6 (4869) 37.4 (5423)

2,2,5 27.5 (3985) 30.9 (4485) 36.9 (5352) 41.4 (6007)

2,3,5 28.6 (4154) 34.1 (4951) 40.8 (5918) 47.8 (6932)

2,0,–5 0.8 (123) 0.7 (98) 0.9 (125) 12.8 (1858)

2,1,–5 6.0 (869) 7.1 (1028) 8.5 (1230) 14.4 (2094)

2,2,–5 8.4 (1214) 10.2 (1481) 12.1 (1754) 20.8 (3018)

2,3,–5 8.4 (1211) 12.1 (1752) 16.2 (2349) 28.7 (4168)

2,0,–10 0.3 (38) 0.1 (8) 0.3 (46) 15.5 (2254)

2,1,–10 0.8 (113) 2.8 (402) 2.9 (423) 12.2 (1773)

2,2,–10 1.5 (217) 3.3 (478) 3.9 (562) 14.1 (2042)

2,3,–10 4.4 (645) 5.5 (799) 8.6 (1243) 23.6 (3418)

2,0,–20 0 (0) 0 (0) 0 (0) 18.9 (2735)

2,1,–20 0.1 (16) 0 (0) 0 (0) 14.2 (2066)

2,2,–20 0.3 (49) 0 (0) 0 (3) 14.9 (2160)

2,3,–20 1.1 (159) 1.1 (153) 0.5 (68) 22.9 (3320)

Table A2. Compressive strength, MPa (psi), with Type III cement

and a 365-kg/m3 (611 lb/yd3) cement factor.

Age—days

Mixture ID 7 14 28 56

*2,0,20 36.9 (5352) 40.6 (5890) 42.6 (6172) 42.9 (6224)

*2,2,20 39.8 (5772) 43.7 (6338) 47.5 (6892) 46.9 (6802)

*2,0,5 33.4 (4847) 38.3 (5550) 42.8 (6201) 45.5 (6601)

*2,2,5 33.8 (4894) 39.5 (5725) 42.1 (6102) 47.2 (6849)

*2,0,–5 1.0 (146) 1.7 (241) 2.8 (404) 18.1 (2631)

*2,1,–5 10.0 (1451) 14.2 (2056) 19.3 (2796) 29.7 (4305)

*2,0,–10 0 (0) 0.5 (66) 0.5 (69) 19.0 (2749)

*2,1,–10 4.1 (590) 5.5 (797) 5.8 (842) 18.0 (2617)

*2,0,–20 0 (0) 0 (0) 0 (0) 23.3 (3376)

*2,1,–20 0 (0) 0.1 (21) 0 (0) 19.2 (2784)

* Denotes Type III cement.

28
Table A3. Compressive strength, MPa (psi), with Type I cement

and a 420-kg/m3 (705 lb/yd3) cement factor.

Age—days

Mixture ID 7 14 28 56

3,0,20 30.9 (4480) 34.2 (4961) 37.6 (5451) 37.7 (5470)

3,1,20 32.9 (4767) 37.4 (5423) 40.9 (5932) 40.7 (5906)

3,2,20 37.3 (5404) 42.4 (6154) 43.6 (6328) 46.6 (6755)

3,3,20 36.6 (5314) 43.9 (6371) 46.8 (6790) 47.2 (6837)

3,0,5 28.5 (4126) 34.1 (4947) 38.2 (5536) 42.0 (6088)

3,1,5 28.1 (4074) 32.6 (4720) 38.2 (5541) 43.3 (6276)

3,2,5 31.3 (4536) 37.8 (5480) 40.8 (5923) 48.3 (7002)

3,3,5 31.0 (4494) 38.0 (5513) 44.1 (6399) 51.2 (7418)

3,0,–5 0.6 (85) 1.2 (167) 1.6 (237) 14.1 (2042)

3,1,–5 7.8 (1127) 11.0 (1601) 12.4 (1797) 19.8 (2874)

3,2,–5 9.9 (1432) 14.1 (2051) 17.0 (2471) 27.2 (3942)

3,3,–5 9.7 (1401) 17.9 (2598) 24.4 (3532) 40.2 (5823)

3,0,–10 0 (0) 0.4 (52) 0.3 (49) 15.2 (2202)

3,1,–10 2.3 (337) 3.7 (533) 4.6 (672) 13.1 (1905)

3,2,–10 3.7 (537) 5.5 (797) 6.9 (1002) 18.4 (2664)

3,3,–10 3.3 (472) 6.3 (915) 9.9 (1442) 26.8 (3890)

3,0,–20 0 (0) 0 (0) 0 (0) 16.8 (2438)

3,1,–20 0 (0) 0 (0) 0 (0) 15.4 (2240)

3,2,–20 0 (0) 0.4 (52) 0.4 (58) 16.8 (2443)

3,3,–20 0 (5) 1.7 (241) 2.8 (401) 24.5 (3556)

29
APPENDIX B: PHASE I, TASK 5 CRITICAL STRENGTHS

Table B1. Critical strength results of early age concrete frozen at –20°C

(–4°F) overnight, then cured at 20°C (70°F). The control concrete was

continuously cured at 20°C (70°F).

Mixture Age Control at Strength attained before freezing—MPa (psi)

ID (days) 2°C (70°F) 1.7 (250) 3.4 (500) 5.2 (750)

2,0 3 23.4 (3400) 21.9 (3178) 23.9 (3461) 24.7 (3584)

7 27.4 (3973) 28.6 (4145) 27.1 (3926) 29.6 (4287)

28 32.3 (4678) 33.6 (4867) 34.0 (4928) 32.8 (4756)

2,1 3 26.0 (3765) 23.9 (3468) 24.3 (3527) 25.0 (3624)

7 32.2 (4673) 30.0 (4350) 29.1 (4225) 29.6 (4289)

28 35.2 (5100) 34.1 (4951) 34.5 (5008) 36.2 (5246)

2,2 3 26.9 (3895) 27.2 (3947) 27.4 (3975) 26.4 (3834)

7 33.8 (4907) 32.7 (4742) 33.4 (4836) 33.5 (4860)

28 39.0 (5654) 36.8 (5336) 37.3 (5411) 38.5 (5588)

2,3 3 28.5 (4131) 28.7 (4164) 28.4 (4119) 28.9 (4192)

7 34.5 (5001) 36.4 (5275) 35.4 (5135) 36.0 (5213)

28 41.4 (6005) 41.2 (5997) 41.4 (6005) 40.6 (5890)

3,0 7 32.5 (4716) 31.8 (4610) 31.8 (4605) 32.4 (4704)

14 36.9 (5348) 34.8 (5039) 36.5 (5293) 36.5 (5296)

29 37.0 (5362) 35.7 (5178) 38.4 (5574) 39.1 (5668)

3,1 7 36.4 (5279) 33.6 (4867) 35.2 (5098) 35.1 (5086)

14 37.6 (5447) 35.6 (5157) 37.5 (5435) 39.0 (5661)

29 40.5 (5875) 40.0 (5805) 41.1 (5960) 41.8 (6059)

3,2 7 40.7 (5904) 39.2 (5691) 40.4 (5857) 40.4 (5857)

14 43.2 (6260) 42.3 (6137) 43.3 (6281) 44.9 (6505)

29 45.0 (6526) 46.7 (6767) 47.5 (6884) 47.8 (6932)

3,3 7 43.9 (6369) 42.5 (6159) 42.5 (6161) 43.3 (6279)

14 45.8 (6644) 44.9 (6508) 46.8 (6779) 48.0 (6956)

29 49.1 (7120) 48.9 (7087) 49.0 (7106) 49.7 (7210)

*2,0 3 29.3 (4251) 18.7 (2714) 30.1 (4367) 28.6 (4152)

7 34.2 (4966) 33.6 (4874) 32.7 (4739) 36.3 (5270)

28 39.1 (5668) 36.6 (5308) 39.1 (5675) 39.1 (5666)

*2,2 3 31.9 (4626) 27.7 (4015) 29.4 (4265) 30.7 (4449)

7 38.6 (5590) 31.1 (4513) 33.9 (4911) 35.5 (5152)

28 41.8 (6064) 37.1 (5378) 39.5 (5732) 40.7 (5906)

* Denotes Type III cement.

30
APPENDIX C: PHASE II, MORTAR SCREENING RESULTS

Table C1. Mortar mix results, 90 fl oz/cwt dosage.

Compressive strength

Reference Reference Reference

Initial Final mix mix mix

Admixture set set 1 day (%) 3 days (%) 28 days (%)

Plain 4:10 7:20 364 100 520 100 3,201 100

ARL-506 3:25 8:00 259 71 1,134 218 6,251 195

ARL-507 3:15 8:05 144 40 276 53 5,231 163

Pozzutec 20 2:50 7:15 185 51 786 151 5,710 178

EX-1 3:30 8:55 246 68 1,075 207 7,089 221

EX-2 3:40 8:40 228 63 833 160 6,749 211

EX-3 3:55 8:10 216 59 1,018 196 5,840 182

EX-4 3:45 7:40 428 118 1,159 223 5,611 175

EX-5D 3:40 7:25 309 85 1,193 229 6,208 194

EX-6 3:55 8:15 200 55 568 109 6,616 207

EX-7 3:25 7:55 163 45 604 116 5,209 163

500 g cement

1375 g sand

212.7 mL water (reference mix: 242 mL)

29.3 mL (90 fl oz/cwt) admixture

Ambient mix room temperature @ 50°F (10°C)

Ambient curing temperature @ 35°F (2°C)

Table C1a. Mortar mix results, 240 fl oz/cwt dosage.

Compressive strength

Reference Reference Reference

Initial Final mix mix mix

Admixture set set 3 days (%) 7 days (%) 28 days (%)

Plain 3:40 9:00 0 na 1,114 100 4,448 100

ARL-506 3:05 6:00 no samples

ARL-507 7:10 0 na 943 85 2,055 46

Pozzutec 20 5:40 10:15 0 na 436 39 999 22

EX-1 3:00 1,680 na 3,684 331 5,054 114

EX-2 3:05 6:30 925 na 2,815 253 5,989 135

EX-3 2:20 8:00 1,326 na 4,051 364 7,428 167

EX-4 2:15 7:25 1,115 na 3,721 334 6,693 150

EX-5D 2:15 7:20 1,186 na 2,663 239 6,144 138

EX-6 2:05 10:45 0 na 1,473 132 4,285 96

EX-7 1:55 6:10 788 na 2,569 231 5,466 123

550 g cement

1513 g sand

180.1 mL water (reference mix: 266.2 mL)

86.1 mL (240 fl oz/cwt) admixture

Ambient mix room temperature @ 50°F (10°C)

Ambient curing temperature @ 35°F (2°C)

31
Table C2. Mortar mix results, 90 fl oz/cwt dosage.

Compressive strength

Reference Reference Reference

Initial Final mix mix mix

Admixture set set 1 day (%) 3 days (%) 28 days (%)

Plain 2:05 2:45 114 100 1,311 100 4,158 100

Pozzutec 20 2:26 2:48 236 208 1,444 110 4,726 114

EY-1 2:19 2:51 189 166 1,538 117 5,151 124

EY-3 2:40 5:20 153 134 1,471 112 4,995 120

EY-7 3:35 7:30 480 422 1,373 105 4,629 111

EY-8* 5:35 183 160 1,031 79 4,070 98

EY-10 2:10 6:45 240 211 823 63 3,835 92

EY-11* 3:30 550 484 1,243 95 4,389 106

* Denotes Type III cement.

Table C3. Mortar mix results, 90 and 150 fl oz/cwt dosage.

Compressive strength

Reference Reference Reference

Initial Final mix mix mix

Admixture set set 3 days (%) 7 days (%) 28 days (%)

Plain 3:10 7:40 70 100 760 100 3,525 100

Pozzutec 20 @ 90 2:50 6:20 185 264 1,090 143 3,268 93

EZ-1 @ 90 2:30 5:30 210 300 990 130 2,864 81

EZ-1 @ 150 3:05 5:25 225 321 1,375 181 3,960 112

EZ-2 @ 90 2:15 5:05 325 464 1,325 174 3,094 88

EZ-2 @ 150 2:10 4:45 300 429 1,975 260 4,805 136

EZ-3 @ 90 2:15 4:35 330 471 1,725 227 4,038 115

EZ-3 @ 150 2:05 4:30 165 236 1,585 209 4,725 134

EZ-4 @ 90 2:10 5:05 390 557 1,480 195 4,065 115

EZ-4 @ 150 1:55 4:50 200 286 1,185 156 4,368 124

EZ-7 @ 90 3:45 5:50 525 750 1,345 177 4,214 120

EZ-7 @ 150 3:30 6:10 170 243 1,305 172 4,450 126

32
APPENDIX D: PHASE II, CONCRETE TESTING RESULTS

Table D1. Mix data and plastic properties.

Mix # 12345 6

MB-VR (fl oz/cwt) 0.90 1.30 1.35 1.20 1.35 1.35

Pozzutec 20 (fl oz/cwt) — 90.00 150.00 — — —

ARL-506 (fl oz/cwt) — — — 90.00 150.00 —

ARL-507 (fl oz/cwt) ————— 90.00

Cement (lb/yd) 612 612 608 619 613 609

Sand (lb/yd) 1,250 1,314 1,305 1,329 1,317 1,308

Stone (lb/yd) 1,801 1,800 1,788 1,820 1,804 1,791

Water (lb/yd) 258 244 243 247 244 243

w/c 0.422 0.399 0.400 0.399 0.398 0.399

Water reducer (%) — 5.4 5.8 4.3 5.4 5.8

Air (%) 6.2 5.6 6.2 4.5 5.4 6.0

Slump (in.) 5.00 8.00 9.00 7.50 6.25 7.50

Table D1a. Hardened properties.

Mix # 1 2345 6

MB-VR (fl oz/cwt) 0.90 1.30 1.35 1.20 1.35 1.35

Pozzutec 20 (fl oz/cwt) — 90.00 150.00 — — —

ARL-506 (fl oz/cwt) — — — 90.00 150.00 —

ARL-507 (fl oz/cwt) ————— 90.00

70°F Comp. strength

1 day 2,320 3,270 2,850 3,240 3,060 2,490

7 days 3,780 4,900 5,200 5,620 5,230 4,720

28 days 4,710 6,550 6,600 6,500 6,250 5,930

14°F Comp. strength

1 day NA 190 120 380 250 50

7 days NA 530 510 470 410 170

28 days NA 910 1,170 920 1,060 420

70°F Set time (hr:min)

Initial 3:56 3:41 3:34 2:48 2:30 4:03

Final 5:21 4:36 4:21 3:25 3:09 4:49

14°F Set time (hr:min)

Initial NA 9:02 9:10 7:29 7:31 9:27

33
Table D2. Mix data and plastic properties.

Mix # 12345 6

MB-VR (fl oz/cwt) 0.90 1.40 1.55 1.45 1.40 1.40

Pozzutec 20 (fl oz/cwt) — 90.00 — — — —

ARL-507 (fl oz/cwt) — — 90.00 150.00 — —

EX-4 (fl oz/cwt) ———— 90.00 150.00

Cement (lb/yd) 615 614 614 605 611 607

Sand (lb/yd) 1,256 1,319 1,319 1,300 1,313 1,304

Stone (lb/yd) 1,812 1,807 1,807 1,781 1,798 1,787

Water (lb/yd) 278 248 248 234 254 246

w/c 0.453 0.404 0.404 0.387 0.417 0.406

Water reducer (%) — 10.80 10.8 15.8 8.6 11.5

Air (%) 4.5 5.0 5.0 7.0 5.0 6.0

Slump (in.) 4.00 5.50 5.00 6.25 4.25 5.00

Table D2a. Hardened properties.

Mix # 12345 6

MB-VR (fl oz/cwt) 0.90 1.40 1.55 1.45 1.40 1.40

Pozzutec 20 (fl oz/cwt) — 90.00 — — — —

ARL-507 (fl oz/cwt) — — 90.00 150.00 — —

EX-4 (fl oz/cwt) ———— 90.00 150.00

70°F Comp. strength

1 day 2,500 3,040 2,580 2,430 2,590 1,910

7 days 4,430 6,360 5,630 5,530 4,820 4,310

28 days 5,520 7,400 6,810 6,490 5,840 5,460

14°F Comp. strength

1 day NA 160 120 100 270 150

7 days NA 840 420 290 870 730

28 days NA 1,940 1,830 2,280 1,590 1,700

70°F Set time (hr:min)

Initial 4:07 3:28 3:44 3:44 3:05 2:25

Final 5:15 4:26 4:42 4:56 4:06 3:20

14°F Set time (hr:min)

Initial NA 9:02 10:00 9:36 9:03 9:20

34
Table D3. Mix data and plastic properties.

Mix # 1 2345678

MB-VR (fl oz/cwt) 1.00 2.00 1.80 1.10 1.80 1.10 2.00 1.60

Pozzutec 20 (fl oz/cwt) — 90.00 ——————

EX-3 (fl oz/cwt) — — 90.00 150.00 ————

EX-5D (fl oz/cwt) ———— 90.00 150.00 — —

EY-1 (fl oz/cwt) —————— 90.00 150.00

Cement (lb/yd) 614 611 609 611 613 615 613 613

Sand (lb/yd) 1,252 1,313 1,309 1,312 1,316 1,320 1,316 1,316

Stone (lb/yd) 1,806 1,799 1,793 1,798 1,803 1,808 1,803 1,803

Water (lb/yd) 279 246 252 242 252 246 254 245

w/c 0.453 0.403 0.413 0.396 0.411 0.400 0.415 0.400

Water reducer (%) — 11.8 9.7 13.3 9.7 11.8 9.0 12.2

Air (%) 4.8 5.5 5.4 5.8 5.0 5.1 4.8 5.4

Slump (in.) 3.75 5.75 4.50 4.75 4.50 5.00 3.75 5.25

Table D3a. Hardened properties.

Mix # 1 2345678

MB-VR (fl oz/cwt) 1.00 2.00 1.80 1.10 1.80 1.10 2.00 1.60

Pozzutec 20 (fl oz/cwt) — 90.00 ——————

EX-3 (fl oz/cwt) — — 90.00 150.00 ————

EX-5D (fl oz/cwt) — — — — 90.00 150.00 — —

EY-1 (fl oz/cwt) — ————— 90.00 150.00

70°F Comp. strength

1 day 2,460 2,940 2,600 2,390 2,620 1,940 1,970 1,660

7 days 4,330 5,260 3,890 4,450 3,990 4,460 3,610 3,370

28 days 5,060 6,950 4,850 5,380 5,490 5,820 4,530 4,590

14°F Comp. strength

1 day NA 210 270 240 300 270 120 70

7 days NA 1,900 1,790 2,600 2,230 2,280 880 800

28 days NA 3,700 2,830 3,700 2,630 2,880 1,130 1,460

70°F Set time (hr:min)

Initial 4:12 3:43 3:14 2:43 3:12 3:06 4:41 5:57

Final 5:20 4:24 4:07 3:35 4:14 3:53 6:20 7:04

14°F Set time (hr:min)

Initial NA 7:53 7:41 7:41 8:00 10:58 11:40 13:41

35
Table D4. Mix data and plastic properties.

Mix # 1 2 3 4 5 6 7 8 9 10

MB-VR (fl oz/cwt) 0.85 1.30 1.80 2.00 1.10 0.75 1.60 2.35 0.80 0.30

Pozzutec 20 (fl oz/cwt) — 90.00 — — — — ————

EY-3 (fl oz/cwt) — — 90.00 150.00 — — ————

EY-7 (fl oz/cwt) — — — — 90.00 150.00 ————

EY-10 (fl oz/cwt) — — — — — — 90.00 150.00 — —

EY-11 (fl oz/cwt) — — — — — — — — 90.00 150.00

Cement (lb/yd) 611 617 602 603 604 604 601 613 612 620

Sand (lb/yd) 1,281 1,360 1,262 1,265 1,331 1,333 1,260 1,235 1,349 1,367

Stone (lb/yd) 1,748 1,815 1,770 1,776 1,776 1,778 1,769 1,805 1,800 1,824

Water (lb/yd) 261 223 279 283 237 225 293 319 239 236

w/c 0.427 0.361 0.463 0.469 0.392 0.373 0.488 0.520 0.391 0.381

Water reducer (%) — 14.6 0.0 0.0 9.2 13.8 0.0 0.0 8.4 9.6

Air (%) 5.6 5.8 6.0 5.6 6.6 7.2 5.2 4.6 5.8 5.0

Slump (in.) 5.00 5.75 4.50 4.00 5.00 6.25 4.50 3.00 4.00 4.00

Table D4a. Hardened properties.

Mix # 1 2 3 4 5 6 7 8 9 10

MB-VR (fl oz/cwt) 0.85 1.30 1.80 2.00 1.10 0.75 1.60 2.35 0.80 0.30

Pozzutec 20 (fl oz/cwt) — 90.00 — — — — ————

EY-3 (fl oz/cwt) — — 90.00 150.00 — — ————

EY-7 (fl oz/cwt) — — — — 90.00 150.00 ————

EY-10 (fl oz/cwt) — — — — — — 90.00 150.00 — —

EY-11 (fl oz/cwt) — — — — — — — — 90.00 150.00

70°F Comp. strength

1 day 2,440 3,240 1,780 1,790 2,870 2,870 1,580 1,280 2,380 2,140

7 days 4,430 6,190 4,280 4,360 4,480 4,630 4,060 3,820 4,540 5,210

28 days 5,240 7,300 5,090 5,240 5,130 5,550 4,930 4,670 5,410 6,180

14°F Comp. strength

1 day NA 110 80 30 150 300 170 130 420 320

7 days NA 1,620 1,580 260 890 1,680 1,260 40 170 470

28 days NA 2,370 530 260 1,720 2,480 590 550 2,470 3,680

70°F Set time (hr:min)

Initial — — — 5:01 — — 3:02 3:43 2:53 2:19

Final 2:40* — — 6:50 3:56 3:23 4:44 5:16 4:24 3:04

14°F Set time (hr:min)

Initial NA 8:53 8:00* 11:45 8:00* 7:30* 8:51 8:59 8:45* 8:00*

* Denotes estimated set times.

36
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VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503.

October 1996

Freezing Temperature Protection Admixture for Portland Cement Concrete

Charles J. Korhonen and John W. Brook

U.S. Army Cold Regions Research and Engineering Laboratory

72 Lyme Road Special Report 96-28

Hanover, New Hampshire 03755-1290

Office of the Chief of Engineers

Washington, D.C. 20314-1000

Approved for public release; distribution is unlimited.

Available from NTIS, Springfield, Virginia 22161

46

Antifreeze admixture Freeze–thaw Winter construction

Cold-weather concrete Thermal protection

UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED UL

For conversion of SI units to non-SI units of measurement consult ASTM Standard E380-93, Standard Practice for Use of

the International System of Units, published by the American Society for Testing and Materials, 1916 Race St., Philadelphia, Pa. 19103.

A number of experimental admixtures were compared to Pozzutec 20 admixture for their ability to protect fresh

concrete from freezing and for increasing the rate of cement hydration at below-freezing temperatures. The

commercial accelerator and low-temperature admixture Pozzutec 20 served as the reference admixture for this

project as it has been a successful product of Master Builders for winter concreting during the past several years.

Over thirty-five experimental admixture candidates were tested. Of these, one experimental admixture, codenamed EY-11, a nonchloride admixture, outperformed all the others and was selected as the admixture to be

considered for future commercialization. It was demonstrated by laboratory evaluation that the Pozzutec 20

admixture did not contribute to corrosion of embedded steel reinforcement. The EY-11 admixture, although still

under examination, also did not contribute to corrosion in a newer and different laboratory test. Based on a

knowledge of its constituents, EY-11 is not expected to contribute to corrosion under laboratory conditions or in

the field. The low and medium dosages (60 and 100 mL/kg [90 and 150 fl oz/cwt]), of EY-11 produced freeze–

thaw-durable concrete, but the highest dosage examined, 160 mL/kg (240 fl oz/cwt), did not. The middle

dosage (100 mL/kg) protected concrete down to the low-temperature goal of this project, –5°C (23°F). The

prototype admixture, EY-11, affords superior low-temperature protection compared to existing accelerating

admixtures, as well as good durability. Unfortunately, it did not provide the desirable rapid setting and strength

gain of concrete at above-freezing temperatures that field engineers and concrete technicians would like.