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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