Center for

By-Products

Utilization

CLEAN COAL BY-PRODUCTS UTILIZATION IN

ROADWAY, EMBANKMENTS AND BACKFILLS

By Tarun R. Naik, Viral M. Patel, and

Amr A. Hassaballah

CBU-1991-18

REP-132

A CBU Report

Department of Civil Engineering and Mechanics

College of Engineering and Applied Science

THE UNIVERSITY OF WISCONSIN - MILWAUKEE

ACKNOWLEDGEMENT

The Center for By-Products Utilization would like to thank the

Radian Corporation, Austin, TX and Electric Power Research

Institute, Palo Alto, CA for their financial support and help in

the execution of this research project. We would also like to

thank the College of Engineering and Applied Sciences, the Office

of Industrial Research and Technology Transfer of the Graduate

School of the University of Wisconsin - Milwaukee, WI for their

continuing support and help to the Center for By-Products

Utilization.

The Center was established by a generous grant from the

Dairyland Power Cooperative, LaCrosse, WI; Madison Gas and Electric

Company, Madison, WI; National Minerals Corporation, St. Paul, MN;

Northern States Power Company, Eau Claire, WI; Wisconsin Electric

Power Company, Milwaukee, WI; Wisconsin Power and Light Company,

Madison, WI; and, Wisconsin Public Service Corporation, Green Bay,

WI. Their financial support and continuing help and encouragement

is gratefully acknowledged.

-3-

1.0 GENERAL

1.1 Introduction

It is estimated that over 90% of the solid by-products

generated from electricity production is from the use of coal-based

technologies(1). This production is estimated to increase over the

next decade in the United States. The need for reducing air

emissions from coal-fueled plants, particularly use of eastern

coals, has lead to the use of clean coal and using advanced sulfur

dioxide control technologies. Figure 1 shows clean coal technology

benefits(2)

.

In 1977, the concept of spray dryer absorption began receiving

attention in the United States as a viable technology for removing

SO2 from flue gases(1)

. In this concept, a slurry of hydrated

calcitic or dolomitic lime is atomized in a spray dryer and

injected into the flue gas stream. The sulfur oxides in the gas

react with the alkalies in the atomized droplets to form sulfites

and sulfates as the hot flue gas dries the atomized solution. A

dry by-product is produced and collected in a fabric filter or an

electrostatic precipitator(1).

The calcium spray drying is now a commercially available flue

gas desulfurization (FGD) technology that is used to control SO2

-4-

emissions from electric utility generating stations. Currently, at

least 14 power plants use this technology to reduce air emissions

in United States. Although considerable attention has been given

to the development of calcium spray drying within the electric

utility industry, very little research concerning the utilization

of this by-product in the construction industry has been done.

Most of the available studies(1,3)

have provided physical properties,

chemical properties and engineering data on the spray dryer by-

products. Many of the chemical and physical properties of the

calcium spray drying wastes are different from those of

conventional fly ash and FGD scrubber sludge(3). These differences

could require changes in typical construction practices where the

by-product can be potentially used as an additive in structural

fills, synthetic gravels, artificial reef blocks, and mineral wool.

Such changes may also impact the overall economics of the calcium

spray drying technology.

U.S. Department of Energy has conducted a world wide study on

waste disposal/utilization(4). The project investigated potential

utilization options for by-products of the advanced coal combustion

technologies. The potential spray dryer by-product applications

are listed below:

-5-

(1) Agriculture

(a) Soil Amendment

(b) Soil Neutralization

(2) Asphalt

(a) Asphalt Paving

(3) Brick Production

(4) Cement

(a) Cement Raw Material

(b) Cement Additive

(5) Ceramic Products

(6) Concrete

(a) Concrete

(b) Concrete Blocks

(7) Fillers

(8) Grout

(9) Mineral Wool

(10) Resource Recovery

(a) Metals Recovery

(b) Sulfur Recovery

(11) Road Construction

(a) Road Base Material

(b) Soil Stabilization

(c) Subbase Stabilization

-6-

(12) Structural Fill

(13) Artificial Aggregate

(14) Waste Water Treatment Agent

1.2 Spray Dryer Characteristics

Properties of calcium spray dryer by-product generally differ

from those of conventional fly ash. However, the conventional fly

ash constitutes a major fraction of this by-product, therefore,

some properties are very similar. The spray dryer by-products are

dry powders, lighter in color than conventional fly ash. Most

spray dryer systems collect fly ash and sulfur reaction products

together downstream from the spray dryer. The spray dryer by-

products consists of 40% to 75% by weight of fly ash. It is

composed of conventional fly ash particles that have been coated

with calcium/sulfur compounds and separate, smaller particles of

calcium/sulfur reaction products. The optimum moisture content for

collecting spray dryer by-products reactions is generally higher

than for corresponding fly ashes(5). Since spray dryer by-products

also have cementitious properties, the construction industry

appears to be a potential field of application for these clean coal

by-products.

1.2.1 Chemical Properties

-7-

1.2.1.1 Solids Characteristics

Calcium spray dryer by-product is mostly fly ash surrounded by

and mixed with calcium/sulfur reaction by-products. A typical

waste stream may be composed of 75 percent fly ash, 16 percent

calcium sulfite hemihydrate (CaSO3, 1/2H2O), 6 percent calcium

sulfate dihydrate (CaSO4, 2H2O), two percent calcium hydroxide

(Ca(OH)2), and 1 percent moisture(6)

.

1.2.2 Physical Properties

1.2.2.1 Abrasiveness, Corrosivity, Hygroscopicity, Self-Hardening

Results of the EPRI Advanced SO2 Control Waste Management Study(5)

indicate that spray dryer by-products tends to be moderately

corrosive when wet, and have hygroscopic tendencies. Wear on some

components of existing spray dryer by-products transfer equipment

exhibit abrasive nature of this by-product(5)

.

-8-

1.2.2.2 Particle Size

Spray dryer waste typically is poorly graded and has a mean

particle size ranging from 0.016 mm to 0.045 mm. Uniformity of the

size distribution of this waste is indicated by the shape (steeply

sloping) of the gradation curve(5). A steeply sloping gradation

curve is indicative of a poorly graded material because it

represents a relatively narrow range of grain sizes. The mean

particle size of calcium spray dryer by-product tends to be smaller

than the 0.045 mm reported for conventional fly ash(5)

.

1.2.2.3 Bulk Density

Literature review(4,5,7)

has reported values for both poured and

packed bulk densities. Poured bulk density refers to a material in

a loose state. Values for poured bulk density ranged from 34 to 60

lb/ft3. Packed bulk density refers to the density of a material

after some degree of vibration. Values for packed bulk density

ranged from 44 to 78 lb/ft3.

1.2.2.4 Specific Gravity

-9-

Values for the specific gravity of spray dryer by-product

range from 2.29 to 3.71 which is comparable to the values reported

for conventional fly ash and cement(4,5,7,8,9)

.

1.2.2.5 Moisture Content

Calcium spray dryer by-product is generated with a free

moisture content ranging from less than 0.1 percent to 3.1 percent

by weight(5,10,11)

. Although it has some initial moisture, spray

dryer by-product can be expected to absorb available moisture from

the atmosphere due to its somewhat hygroscopic nature.

1.2.3 ENGINEERING PROPERTIES

1.2.3.1 Moisture/Density Relationship

Data reported in the literature indicate an optimum moisture

content (the moisture level at which dry density is a maximum)

ranging from 16 to 54 percent, and maximum dry density ranging from

61 to 104 lb/ft3 (5,7,8,12,13,14)

.

1.2.3.2 Strength

-10-

Many different soil strength tests are available to develop

strength data for design use. For spray dryer by-product, data

from unconfined compressive strength tests is the most widely

reported information. Reported 28-day cured strengths of a

cylinder made only of spray dryer by-products ranged from 12 to

3,000 psi(5,7,8,12,13,14)

.

1.2.3.3 Permeability

Literature reported permeability (K) values for calcium spray

dryer by-product range from 9 x 10-10 to 9.7 x 10

-5 cm/sec

(7,12,13,14).

Values reported by EPRI (3.1 x 10-9 to 1.6 x 10

-7 cm/sec) were

obtained from samples that were mixed with water to reach optimum

moisture, then compacted to maximum dry density and cured at 100

percent relative humidity for 28 days(4).

2.0 OVERVIEW OF THE LAB WORK

2.1 Introduction

This report details the laboratory work performed for

establishing the technical feasibility and data for utilizing

spray-dryer by-product as a construction material. The initial

research phase consisted of mix proportioning and casting of

concrete specimens containing spray dryer by-product for

-11-

compressive strength testing purposes. A total of three mixes were

designed and produced at the Center for By-Products Utilization

(CBU) laboratories at the University of Wisconsin-Milwaukee (UWM).

The testing included the determination of various physical and

mechanical properties of both fresh and hardened concrete. All of

the mixes were designed in accordance with the Minnesota DOT

specifications(15)

to achieve a compressive strength of 4000 psi at

28 days.

2.2 Material Selection And Mix Proportioning

2.2.1 General

The concrete was produced in the CBU laboratory using

conventional techniques using a tilting-drum mixer. For economic

reasons, locally available materials were used in the mix

proportions. Hence, an optimum design was developed for the

available materials on the basis of strength, cost, and field

performance. Because of the high potential for this spray dryer

by-product to be used in road construction, the objective was to

determine the effect of adding the spray dryer by-product on the

compressive strength of concrete and its modulus of rupture. All

mixes were air-entrained to resist freeze and thaw. Also, due to a

high sulfur content in the spray dryer by-products, the sulfate

-12-

resistance of concretes incorporating this by-product is being

investigated.

2.2.2 Materials

2.2.2.1 Cement

The cement used in this research program was produced by

LaFarge Corporation. Chemical compositions were determined for the

cement and are reported in Table 1.

Physical properties of the cement were determined in

accordance with the appropriate ASTM standards listed below(16)

.

The temperature and relative humidity in the laboratory were

maintained at 70 + 3 F and 45 + 5%, respectively.

(a) Fineness, Blain Air Permeability (ASTM C 204)

(b) Normal Consistency (ASTM C 187)

(c) Initial and Final Setting Time, Vicat's Apparatus (ASTM C 191)

(d) Soundness (ASTM C 151)

(e) Air Content (ASTM C 185)

(f) Specific Gravity (ASTM C 188)

The results of these tests are given in Table 2.

-13-

2.2.2.2 By-Product Materials

Spray dryer "by-product" from the Northern States Power Plant,

was used for the entire program. Chemical analysis results for the

by-product are reported in Table 3. The spray dryer by-product was

further tested for physical properties in accordance with ASTM C

618 and the findings are presented in Table 4.

2.2.2.3 Aggregates

The coarse and the fine aggregates used in this research

program were obtained from a local ready mixed concrete company

(Central Ready Mix, Inc.). The coarse aggregates were a mixture of

crushed and rounded natural gravel with a 3/4" maximum size. The

fine aggregate was natural sand with a 1/4" maximum size. The

following set of ASTM Standard tests were conducted to determine

the physical properties of the aggregates.

(a) Moisture content (ASTM C 566)

(b) Unit Weight and Volume of Voids (ASTM C 29)

(c) Specific Gravity and Absorption (ASTM C 127 for C. A.) and

(ASTM C 128 for F. A.)

(d) Sieve Analysis (ASTM C 136)

-14-

Fineness modulus for sand was also determined by the ASTM C

136 method. The test data on physical properties of the aggregates

are presented in Tables 5, 6, and 7.

2.3 Mixture Proportioning

A total of three different trial mixes were produced in the

laboratory. One out of these three mixes was a control mix. The

by-product was used as one on one replacement of cement by weight.

The water to cementitious ratio (water divided cement plus spray

dryer by-product) was maintained at 0.47 for all mixes. All mixes

were air-entrained. Details of the mixture proportions and

rheological properties of the three concrete batches are given in

Table 8.

2.4 Manufacture of Concrete and Casting of Test Specimens

All of the three mixes were produced at the laboratory of the

Center for By-Products Utilization at UWM. An electric tilting

drum type mixer having a 5 cu. ft. mixing capacity was used to mix

the concrete. For each mix slump, specific weight, temperature of

the fresh concrete, and the amount of entrained air was determined.

6" x 12" cylinders were cast in accordance with the ASTM C 192 for

measuring the compressive strength of concrete. Rectangular prisms

-15-

were cast for testing the sulfate resistance of these mixes.

Additional prisms were also cast to determine the change in modulus

of rupture due to sulfate attack. All of the specimens were

demolded after 24 hours and immersed in lime saturated water at 73

+ 2 F until the time of test. The cylinders were capped using a

sulfur compound to ensure the faces were parallel and smooth.

2.5 TESTING PROGRAM

The test specimens for all mixes were tested to determine

their uniaxial compressive strength in accordance with the ASTM C

39. The compressive strength data is presented in Table 9. All

prisms were tested in accordance with the ASTM C78 to determine the

modulus of rupture before and after immersing in a 10% sodium

sulfate solution by weight.

The prisms are also being tested to determine the sulfate

resistance of these concrete mixes. A modified ASTM C 1012 is

being followed for the sulfate resistance tests in order to study

the effect of accelerated sulfate attack. Appendix A contains a

detailed description of the test procedure followed for measuring

the sulfate resistance of concrete specimens.

2.5.1 Results and Discussions

-16-

2.5.1.1 Compressive Strength

The Compressive strength data for all the three mixes is

presented in Table 9. The test data shows that all mixes averaged

greater than 4380 psi at 28 days age. The compressive strength was

found to increase with age for all of the mixtures as reported.

The control mix A-0-0 showed the lowest strengths compared to

the other two mixes. The concrete mixture A-10-0 containing 10%

spray dryer by-product produced the highest compressive strengths.

The mix A-50 had 18% higher compressive strengths than control mix

A-0-0, while the mix A-10-0 showed 22% higher compressive strength

as compared to the control mix at 28 day age. The mixes A-50 and

A-10-0 consistently showed higher strengths than A-0-0 at all ages.

At 91 days A-5-0 was 27% higher than A-0-0 and A-10-0 was 30%

higher than A-0-0. Figure 2 shows the plot of the compressive

strengths versus age for all three mixes.

2.5.1.2 Sulfate Resistance Testing

Specimens from all three mixes A-0-0, A-5-0, and A-10-0 are

being tested for sulfate resistance. A modified ASTM C1012

procedure is being followed to obtain accelerated test results.

-17-

The procedure is described in detail in appendix A. The test

results for up to 9 months age is reported in appendix B. The test

results indicate that the density of concrete is constantly

increasing with age. However, this increment is negligible. The

increase in density can be attributed to the formation of more

hydration products.

The mixtures A-5-0 and A-10-0 showed a higher density at all

ages. The fundamental transverse frequency and the pulse velocity

for all mixes is increasing with age. The specimens have not

reached the failure criteria yet.

-18-

4.0 REFERENCES:

(1) Proposal to EPRI for "Clean Coal By-Product Utilization in

Roadways, Embankments and Backfills - 1990-1991 Construction,"

Radian Corporation, NSP, VFL Technology, 1990.

(2) Elliot, T.C., "Coal Handling and Preparations", Power, Vol.

136, No. 1, 110th Year, January 1992, p. 17-32.

(3) GAI Consultants, Inc., "Generic Conceptual Engineering Design

for a 500 MW Coal Fired Power Plant Utilizing a Spray Dryer

for SO2 Control", Electric Power Research Institute, Project

85-105, Palo Alto, California, February 1985.

(3) GAI Consultants, Inc., "Fly Ash Design Manual for Road and

Site Application", EPRI Reports CS-4419, Vol. 1, EPRI CS-5981,

Vol. 1 & 2, February 1986 and October 1988.

(4) Radian Corporation, "Laboratory Characterization of Advanced

SO2 Control By-Products: Spray Dryer Wastes", EPRI CS-5782,

May 1988.

(5) ICF Northwest and Baker/TSA, Inc., "Calcium Spray Dryer Waste

Management Design Guidelines", EPRI CS-5312, September 1987.

-19-

(6) Donnelly, J. R., and Webster, W. C., "Synthetic Gravel from

Dry Flue Gas Desulfurization End-Products", Presented at the

6th International Ash Utilization Symposium, Reno, Nevada,

March 1982.

(7) Donnelly, J. R., Ellis, R. P., and Webster, W.C., "Dry Flue

Gas Desulfurization End-Product Disposal Riverside

Demonstration Facility Experience", Presented at the EPA/EPRI

Symposium on Flue Gas Desulfurization, Hollywood, Florida,

EPRI CS-2897, Vol.2, May 1982.

(8) Phillips, L., "An Evaluation of the Waste Product from a

Calcium Based Dry Flue-Gas Desulfurization System", Thesis

submitted to the University of Tennesse, Knoxville, Tennesse,

June 1970.

(9) Adkins, B. J., "Shawnee Steam Plant - Evaluation of Waste

from Pilot Spray Dryer", Unpublished Report Prepared by TVA,

September 1984.

(10) Radian Corporation, "Characteristics of Waste Products from

Dry Scrubbing Systems", EPRI CS-2766, December 1982.

-20-

(11) Radian Corporation, "Field Evaluation of a Utility Spray Dryer

System", EPRI CS-3954, May 1985.

(12) Webster. W. C., Donnelly, J. R., and Buschman, J. C.,

"Disposal Properties of Dry Scrubber Residues", Presented at

the 42nd Annual Meeting of the International Water Conference,

Pittsburgh, Pennsylvania, October 1981.

(13) Donnelly, J. R., "Disposal and Utilization of Spray Dryer FGD

End-Products", Presented at the Canadian Electrical

Association Seminar on SO2 Removal by Dry Processes, Ottawa,

Canada, October 1981.

(14) Buschman, J.C., Rasmussen, E.L., and Kaplan, S.M., "Disposal

of Wastes from Dry SO2 Removal Processes", Presented at the

Joint Power Generating Conference, Phoenix, Arizona, September

1980.

(15) "Standard Specifications for Construction", Minnesota,

Department of Transportation, St. Paul, 1985, p. 914.

(16) "Annual Book of ASTM Standards", ASTM, Volume 4.01, 4.02,

Philadelphia, PA, 1991.

-21-

REP-132

5/07/92

-22-

Table 1: Chemical Properties of Cement

Chemical

Composition

Cement A

ASTM C 150

Weight %

TYPE I

TYPE II Silicon Dioxide

(SiO2)

21.0

-

20.0% min

Aluminum Oxide

(Al2O3)

4.9

-

6.0% max

Iron Oxide

(Fe2O3)

2.8

-

6.0% max

Calcium Oxide

(CaO)

78.6

-

-

Magnesium

Oxide (MgO)

1.6

6.0% max

6.0% max

Sulfur Trioxide

(SO3)

3.5% max

3.0% max

Total (SiO2 +

Al2O3 + Fe2O3)

28.7

-

-

-23-

Table 2: Physical Properties of Cement

ASTM C 150 Requirements

Test

Cement A

Minimum

Maximum

Type I

Cement

Type II

Cemen

t

Type I

Cement

Type II

Cement

Air Content, %

8.2

-

-

12

12

Fineness (by Air Permeability),

m2/kg

392.5

280

280

-

-

Autoclave Expansion, %

- 0.04

-

-

0.80

0.80

Specific Gravity

3.11

-

-

-

-

Compressive Strength, psi

1 day

3 days

7 days

28 days

1835

3065

4266

5750

-

1800

2800

-

1500

2500

-

-

-

-

-

-

Vicat Time of Initial Set, minutes

175

45

45

375

375

-24-

Table 3: Chemical Properties of NSP Spray Dryer By-Product

Chemical Composition

NSP Spray Dryer

By-Product

ASTM C 618

Weight %

Class F

Class C

Silicon Oxide (SiO2)

31.0

-

-

Aluminum Oxide (Al2O3)

16.7

-

-

Iron Oxide (Fe2O3)

3.8

-

-

Total (SiO2 + Al2O3 +

Fe2O3)

51.5

70% min

50% min

Sulfur Trioxide (SO3)

5.0% max

5.0% max

Calcium Oxide (CaO)

21.3

-

-

Magnesium Oxide (MgO)

3.0

-

-

Loss in Ignition

6.0% max

6.0% max

Available (K2O)

Alkalies (Na2O)

0.5

1.5% max

1.5% max

2.1

-25-

Table 4: Physical Properties of NSP Spray Dryer By-Products

Test

NSP Spray

Dryer

By-Product

ASTM C618

Class F

Class C

Fineness

Amount retained when wet sieved

on No. 325 sieve, %

18.5

43 max

34 max

Pozzolanic Activity Index

With Type I Cement at 28 days,

Percent of Control

With Type II Cement at 28 days,

Percent of Control

With Lime at 7 days, psi

96

99

75 min

75 min

800

75 min

75 min

- Water Required, % of Control

With Cement A

With Cement B

97.5

99.2

105 max

105 max

105 max

105 max Autoclave Expansion, %

With Cement A

With Cement B

- 0.06%

- 0.06%

+0.8% max

+0.8% max

+0.8% max

+0.8% max Specific Gravity

2.43

-

-

Variation

Fineness

Specific Gravity

0.4

1.6

5% max

5% max

5% max

5% max

-26-

Table 5: Properties of Aggregate

Moisture

Content

(%)

Bulk

Specific

Gravity

Bulk

Specific

Gravity

(SSD)

Apparent

Specific

Gravity

Absorption

(SSD) (%)

Unit

Weight

(lb/ft3)

Percent

Voids

(%)

Fineness

Modulus

Gravel #1

0.2

2.66

2.69

2.75

1.3

105.4

36

Gravel #2

Sand #1

0.6

2.69

2.72

2.78

1.2

115.4

31

2.85

Table 6: Sieve Analysis for Fine Aggregate

Sieve Number

Individual %

Retained

Cumulative %

Retained

% Passing

ASTM C 33

% Passing

4

3.4

3.4

96.6

95-100

8

15.0

18.4

81.6

80-100

16

16.1

34.5

65.5

50-85

30

19.0

53.5

46.5

25-60

50

27.3

80.8

19.2

10-30

100

13.4

94.2

5.7

2-10

Pan

5.6

99.8

-

Total

99.8

-27-

-28-

Table 7: Sieve Analysis for Coarse Aggregate

Sieve

Size, Max.

Opening

Individual %

Retained

Cumulative %

Retained

% Passing

ASTM C33

% Passing Gravel

#1

Gravel

#2

Gravel

#1

Gravel

#2

Gravel

#1

Gravel

#2

1"

0

0

0

0

100

100

100

3/4"

7.2

9.6

7.2

9.6

92.8

90.4

90-100

3/8"

72.1

70.4

79.3

80.0

20.7

20.0

20-55

#4

18.8

17.8

98.1

97.8

1.9

2.2

1-10

#8

0.9

1.4

99.0

99.2

1.0

0.8

0-5

Pan

1.0

0.8

100.0

100.0

-

-

-

Total

100.0

100.0

-

-

-

-

-

-29-

Table 8: Description of Mixture Proportions and Properties of Fresh Concrete

MIX NO.

A-0-0

A-5-0

A-10-0

Design Strength, psi

4000

4000

4000

Cement A, lbs./cu.yd.

611

580

550

Spray Dryer By-Product, lbs./cu.yd.

0

31

62

Water, lbs./cu.yd.

290

290

290

Water to Cementitious Ratio

0.47

0.47

0.47

Sand, SSD, lbs./cu.yd.

1450

1450

1450

Max. 3/4" aggregates, SSD, lbs./cu.yd.

1810

1810

1810

Slump, inches

3 ½

3

2 ¼

Air Content, %

7

5.2

4.2

Air Temperature, F

68

68

68

Concrete Temperature, F

73

72

73

Concrete Density, pcf

145

147

149 Air Entraining Agent, DAREX, ml/cu.yd.

300

300

300

-30-

Table 9: Concrete Test Data - 4000 psi (27 MPa) Design Strength

Project: EPRI Clean Coal By-Product Utilization in Roadways, Embankments, and

Backfill - Radian Corporation, Austin, TX.

Mix No.

A-0-0

A-5-0

A-10-0

Design Strength, psi

4000

4000

4000

Spray Dryer By-Product,

Percent

0

5

10

Test Age, Days

Compressive Strength, psi

act.

ave. act.

ave.

act.

ave.

3

2970

3840

3930

3

3060

3015

3660

3725

3770

3840

3

3010

3680

3820

7

3540

4240

4530

7

3520

3520

4490

4365

4600

4565

7

3500

4370

4560

28

4315

5111

5234

28

4403

4380

5252

5175

5447

5345

28

4422

5164

5358

56

4527

5783

6013

56

4624

4525

5376

5630

5853

5925

56

4421

5730

5915

91

4828

6278

6101

91

4845

4875*

6278

6180*

6313

6320*

91

4951

5995

6543

-31-

* Test was done when concrete age was 94 days

-32-

Appendix A

Sulfate Resistance Test Procedure

per ASTM C-1012 (modified)

-33-

Modified ASTM C-1012 Procedure for

Sulfate Resistance of Concrete Specimens

Specimen Size: 3"x4"x16" for sulfate resistance measurements, and 6"x12" cylinders for

compressive strength.

Solution: Na2SO4 @ 10% concentration by weight.

Procedure

Cast nine 3"x4"x16" prism specimens per concrete mixture in accordance with ASTM C666.

Demold at 24 ± 1 hours and store in moisture curing room in accordance with ASTM C39.

At the 28-day age measure the following parameters for all prisms:

(1) weight in air and water to the nearest 0.01 lb.

(2) length to the nearest 0.0002 in, in accordance with ASTM C490.

(3) modulus of rupture, in accordance with ASTM C78.

(4) pulse velocity, in accordance with ASTM C597.

(5) transverse frequency, in accordance with ASTM C666.

(6) longitudinal frequency, in accordance with ASTM C666.

Measure the weight of prisms in air and water to the nearest .01 lb.

Soak three 3"x4"x16" prism specimens per mix in the 10% Na2SO4 solution and cover it "air

tight", to minimize water/solution evaporation, in plastic containers (tanks). The plastic

tanks should be stored in constant room temperature (73 + 3 F). The rest of the 3"x4"x16"

prism specimens remain in the moisture room.

At the age of 1, 2, 3, 4, 8, 13, 15 weeks, and at 4, 6, 9, 12 months, measure the following

parameters for the three soaked prism specimens:

(1) weight in water & air to the nearest 0.01 lb.

(2) length to the nearest 0.001 in, in accordance with ASTM C 490.

(3) pulse velocity, in accordance with ASTM C 597.

(4) transverse frequency, in accordance with ASTM C 666.

(5) longitudinal frequency, in accordance with ASTM C 666.

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Failure Criteria:

one or more of the following

0.2% change in length.

40% loss of the original dynamic modulus.

Precautions:

(1) Calibrate and keep the length comparator in the same exact position throughout the test for

length measurements.

(2) The plastic grid below the specimens should not be very thick (about 1/4 inch).

(3) The specimens faces should be equally exposed to the solution in all directions.

(4) While casting the specimens insert studs in the end plates of molds until 3 threads remain

visible. During the measurements of the above parameters, handle the studs with care so

they do not become loose or fall off.

(5) Check the pH level of the solution periodically to maintain consistency.

(6) Change the Na2SO4 solution every time the specimens are tested.

(7) Handle the specimens with care to minimize material/concrete loss.

(8) In measuring the above parameters, take one specimen at a time only, out of the tank.

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Appendix B

Sulfate Resistance Data Sheets