United States
Environmental Protection Agency
Research and Development
U.S. EPA Workshop on Acid Deposition
Effects on Portland Cement Concrete
and Related Materials
Final Report
Atmospheric Sciences Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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620R86001
February, 1986
FINAL REPORT OF THE
U.S. EPA WORKSHOP ON ACID DEPOSITION EFFECTS ON PORTLAND CEMENT CONCRETE AND
RELATED MATERIALS
Workshop Chairmen
John Spence and Fred Haynie
Atmospheric Sciences Research Laboratory
Research Triangle Park, North Carolina 27711
ATMOSPHERIC SCIENCES RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
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DISCLAIMER
Although the research strategies workshop described in this internal report has been funded
by the U.S. Environmental Protection Agency, under Contract 68-02-3839 to Northrop Services, Inc., it
has not been subjected to the Agency's required peer and policy review and therefore does not
necessarily reflect the views of the Agency and no official endorsement should be inferred. Mention
of trade name or commercial products does not constitute endorsement or recommendation for use.
A questionnaire was used at the workshop to stimulate discussion and was sent to foreign
scientists for comment. Note that the foreign scientists who responded to this questionnaire
expressed differing viewpoints and do not necessarily endorse all recommendations in this report.
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TABLE OF CONTENTS
Disclaimer ----------------------------------------------------------------- "
Acknowledgements --------------------------------------------------------- IV
1. Executive Summary ------------------------------------------------- 1
2. Introduction ------------------------------------------------------- 2
3. Discussion -------------------------------------------------------- 3
Speculations on How Acid Deposition Might Affect Plain Concrete Materials — 3
Speculations on How Acid Deposition Might Affect Reinforced Concretes ----- 4
Recommended Research Program ---------------------------------- 4
Field Case Studies -------------------------------------------- 4
Laboratory Research ------------------------------------------ 5
Responses to Questionnaire ---------------------------------------- 9
Appendices
A. Workshop Agenda
B. Workshop Participants
C. Questionnaire
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ACKNOWLEDGEMENTS
We wish to thank Dr. Geoffrey Frohnsdorff, Building Materials Division, National Bureau of
Standards, for chairing and summarizing workshop discussions. The efforts of Ms. Linda Cooper,
Workshop Coordinator, Northrop Services, Inc., in planning and arranging the workshop and in
producing this final report are gratefully acknowledged.
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SECTION 1
EXECUTIVE SUMMARY
There is no direct evidence that acid deposition has a significant economic effect on portland
cement concrete and related materials. However, acid deposition may:
1. Convert the alteration layer caused by the action of CC>2 from carbonate
compounds to more soluble materials.
2. Cause corrosion of the steel rebar if the alteration layer reaches the steel.
3. Increase the rate of neutralization of the matrix by adding to the effects of CO2-
Although effects are not likely to be large, a research program is needed to determine whether they
occur and to assess their magnitudes.
Acid deposition could possibly damage the ties and hangers (usually made of galvanized steel
or carbon steel) that support masonry and concrete walls of building structures. Failure of these
supporting elements due to corrosion could lead to catastrophic failure of the wall.
Two study programs were recommended by workshop participants:
1. Field Case Studies: to select a few structures that are located in high deposition
areas and conduct microscopic and microanalytical studies of specimens from
structures.
2. Laboratory Research: to determine and quantify environmental factors affecting
the rate of attack of cracked and uncracked concrete and mortar by acid deposition.
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SECTION 2
INTRODUCTION
The Atmospheric Sciences Research Laboratory (ASRL) program, Effects of Acid Deposition on
Materials, is planned and conducted for Task Group G, Effects on Materials and Cultural Resources;
this is one of several task groups within the National Acid Precipitation Assessment Program
(NAPAP). One of the objectives of the NAPAP is to provide a scientific data base on the causes and
effects of acid precipitation.
Task Group G has two overall areas of responsibility in developing a research program on the
effects of wet and dry acid deposition on materials:
1. Develop data bases and methods for assessing the materials-related benefits of acid
deposition control policies.
2. Establish guidelines for protecting individual structures from the effects of acid
deposition or for restoring damaged structures.
The first responsibility is identified primarily with the regulatory activities of the U.S.
Environmental Protection Agency (EPA), whereas the second responsibility concerns the National
Park Service (NPS).
Man-made and naturally occurring materials used extensively in structures such as buildings,
monuments, electrical transmission towers, and highway bridges are exposed to acid deposition.
ASRL's program is concerned with studying the effects of acid deposition on materials of
construction such as galvanized steel, weathering steel, exterior paints, and portland cement
concrete, whereas the program with the NPS is primarily concerned with studying the effects on
materials found in cultural resources.
The objective of ASRL's program is to design and conduct a materials research program that
will differentiate between normal expected weathering and the accelerated deterioration
attributed to acid deposition, including both wet and dry deposition. Material damage functions
that quantify physical damages with significant environmental parameters causing the damage will
be derived for use in cost-benefit models.
The purpose of this workshop was to provide recommendations from which a research
program for developing damage functions for the effects of acid deposition on portland cement
concrete structures can be developed.
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SECTION 3
DISCUSSION
SPECULATIONS ON HOW ACID DEPOSITION MIGHT AFFECT PLAIN CONCRETE MATERIALS
The cement paste matrix (M) consists of anhydrous cement compounds [tricalcium silicate
(CaS)*, dicalcium silicate (C2S), tricalcium aluminate (CsA), and calcium aluminoferrite (Fss)l, their
hydration products [e.g., calcium silicate hydrate (C-S-H), calcium hydroxide (CH), and two phases
containing aluminum and iron (AFt and AFm)], pores, and an altered layer (a) caused by weathering
that contains calcium carbonate (CC), and carbonate analogs of AFt and AFm as well as residues of
the other phases.
Figure 1. Cement Paste Matrix.
The aggregate particles (A), both fine and coarse, consist of either silicious and carbonate
materials or both. The paste matrix (M) is known to be substantially modified close to the aggregate
particle surfaces, but the effects on concrete durability have not yet been determined. The thickness
of the layer of alteration products (a) increases as the square root of time (Vt). The rate depends on
the permeability of the concrete that varies markedly with the water to cement ratio of the original
mixture. Whereas the pH water in the pores of the paste before the alteration is about 13, it drops
to below 9 after alteration by CO2- Normal cracks appear to have little effect on the rate of advance
of the alteration front.
* In this cement industry nomenclature, C = CaO and S = SiO2; other symbols used in this section are
A = AI203/ H = H2O, and C = C02-
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It is speculated that acid deposition may either:
1. convert a portion of the alteration layer from carbonate compounds to compounds
of stronger acids, or
2. increase the rate of neutralization of the matrix by adding to the effects of C02-
In either case, the effect is not expected to be large, but research is needed to establish this.
Possible degradative effects that may result from acid deposition are as follows:
• Formation of more soluble compounds causing enhanced rate of leaching
• Expansion followed by spading
• Discoloration
• Enhanced propensity for freeze/thaw damage.
SPECULATIONS ON HOW ACID DEPOSITION MIGHT AFFECT REINFORCED CONCRETES
Acid deposition will affect the concrete portion of reinforced concrete in much the same way
as unreinforced concretes. However, when the alteration layer reaches the steel rebar (R, see
Figure 1), and the pH falls to about 9 or below, the passivation of steel against corrosion will be lost.
The steel would then corrode at a rate depending on factors including:
• 02 concentration
• H2O concentration
• Electrical conductivity of the concrete.
Research is needed to determine if acid deposition causes significant changes in the times to
corrosion and rates of corrosion of steel in reinforced concrete. (Reinforcement in masonry poses a
different problem, which is discussed in the Laboratory Research section (see Figure 2).
RECOMMENDED RESEARCH PROGRAM
Both field and laboratory research studies are recommended to determine the effects of acid
deposition on portland cement concrete and related materials.
Field Case Studies
The objective of a field investigation is to seek evidence of effects of acid deposition on
concrete. The effects might include the following:
• Discoloration
• Increased freeze/thaw damage
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• Corrosion of reinforcing steel
• Other evidence of degradative effects.
The approach would be to select a few candidate structures believed to have a particularly high
probability of attack by acid deposition.
Microscopic and microanalytkal studies of specimens from the structures should be made
similar to those recommended for the lab studies. It is important this work be done by an expert in
concrete technology and microscopic failure analysis.
Laboratory Research
The objective of a laboratory study would be to determine and quantify factors affecting the
rate of attack of cracked and uncracked concrete and mortar by acid deposition.
1. Variables to be investigated should include:
a) Environmental parameters
(1) Pollutants:
S02
NOX
HCI
Particulate matter
Combinations of the above
(2) Meteorological parameters:
Various relative humidities
Condensation
Water (with pollutants)
Wetting and drying cycles (need to know time of wetness)
Temperature (including temperature cycles)
Wind speed and direction
b) Materials
Cement
Mineral ad mixtures (low priority)
Air-entraining admixtures
Aggregates (Silicious and carbonate types)
Various mixture proportions
Reinforcement (exclude prestress)
Surface-to-volume ratio
Cover for steel
Cracks (with steel)
Specifically, materials recommended for use in the main study are:
Type f cement
White cement (for discoloration study using pastes)
Silicious fine aggregate
Silicious coarse aggregate
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Carbonate coarse aggregate
Air-entraining agent (to obtain 6% ± 1% air).
2. Specimens
a) Pastes
Various water to cement (w/c) ratios (0.7 - 0.4)
b) Mortar
Type N mortar with
(1) Masonry cement
(2) Portland cement/lime
c) Concrete
(1) Very porous
(2) Moderately porous
d) Reinforced concrete
(1) As for concrete, but with embedded polished steel tabs; use two depths of cover
(2) As for the above, but with the standard width of cracks (as defined by the American
Concrete Institute [ACI] Standard ACI 318) and one other crack width
e) Reinforced mortar
Use simulated mortar joints (Figure 2).
joint
reinforcement
face shell of
concrete block
mortar
Figure 2. Simulated Mortar Joint
(This specimen to be used in studies of effect of dry deposition)
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3. Exposures
a) Dry deposition; use closed chamber
b) Wet deposition; use
(1) Spray with various pollutant concentrations
(2) Spray with water at pH 5.6.
(Requires alternate wetting and drying.)
4. Damage measurements
a) Pastes
(1) Loss of material
(a) Weightless
(b) Run-off analysis
(c) Recession
(2) Alteration of phases
(a) X-ray diffraction (XRD)
(b) Microanalysis
(c) pH
(3) Alteration of microstructures
(a) Scanning electron microscopy (SEM)
(b) Permeability
(4) Change of mechanical properties
(a) Surface hardness
b) Concrete
(1) As for pastes and mechanical properties (fc)
c) Reinforced concrete
(1) Corrosion potential
(2) Bond strength
d) Reinforced mortar
(1) As for reinforced concrete.
An overall diagram for determining failure mechanisms and service life predictions from the
exposure study is shown in Figure 3.
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Concrete materials
Mixture design
Mixing and curing
Concrete
properties
Environmental
variables
Experiments
• accelerated
• outdoor
If necessary,
repeat the
research cycle
Evaluation of
experimental
results
Service life
prediction
Multivariant
discriminatory
analysis
Rate of
degradation
Rank system properties and
environmental variables with
respect to time-to-failure
Failure
mechanisms
Figure 3. Diagram For Exposure Study.
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RESPONSES TO QUESTIONNAIRE
The responses to the questionnaire that was used in the workshop to stimulate discussion and
that was sent for foreign scientists are compiled below.
A. Response provided by Or. Geoffrey Frohnsdorff, chairman of workshop discussions.
1. Please list any research on the effects of acid deposition on cement concrete materials that
is in progress or that is being planned.
The only research on the effects of acid deposition on cement concrete materials
that the workshop participants believed to be in progress or being planned was:
• The National Park Service was to support research on the effects on mortars
to be carried out by a Mr. Langmuir in Colorado (this was mentioned by John
Morgan).
• The Department of Energy is supporting studies of the use of concretes for
encapsulation of low-level radioactive wastes. This work, which is being
carried out at Pennsylvania State University by Dr. Delia Roy and colleagues,
probably includes studies of acid attack of the concrete materials.
2. Are there existing experimental programs that could incorporate the study of acid
deposition?
The workshop participants mentioned a few existing experimental programs that
could incorporate a study of the effects of acid deposition on concrete. These
include:
• Brookhaven National Laboratory's studies of the effects of acid deposition on
crops in the field exclusion shelters.
• Work being planned by the Waterways Experiment Station of the U.S. Army
Corps of Engineers on the effect of aggressive waters on the service life of
repaired and rehabilitated concrete.
• The Portland Cement Association's (PCA) continuing studies of factors
affecting the durability of concretes.
• The National Bureau of Standards' (NBS) continuing studies of factors
affecting the durability of building materials.
• The Construction Materials Research Council (CMRC) of the ACI is planning to
support research on effects of chlorides in concrete on the corrosion of
reinforcing steel.
• The National Concrete Masonry Association has a corrosion study under way
on unreinforced concrete masonry walls.
3. Does evidence exist for acid deposition damage to cement concrete materials (structures)?
If so, where?
The workshop participants knew of no conclusive evidence to show that acid
deposition had an effect on Portland cement concretes. However, it was
mentioned that Dam and Lock No. 2 on the Monongahela River near Pittsburgh
may show evidence of the effects of acid deposition.
An excellent review paper entitled "The Effects of Neutralization of Concrete by
Carbon Dioxide" was given at the Fifth International Symposium on the
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Chemistry of Cement in Tokyo in 1968. The paper, which was by Hamada,
included reference to surveys of actual buildings, including large "chimneys. In a
brief reference to neutralization of concrete in chimneys, Hamada mentioned
that the neutralization was due to the effects of both CC>2 and SC»2. He also
referred to studies by other workers on the effects of pollutants in chemical
plants.
6. Is an experimental program needed to study the effects of acid deposition on cement
concrete materials?
Some other references that might be useful in designing an experimental
program are as follows:
• A series of papers by P.K. Mehta and O. Gjorv on Sulfate Attack of Cement
Pastes by Sulfate Solution at Constant pH.
• A paper by Paul Brown, on an extension of the work of Mehta and Gjorv to
the study of sulfate attack at different constant pHs. (P. Brown, An
Evaluation of the Sulfate Resistance of Cement in a Controlled Environment,
in Cement and Concrete Research, Pergamon Press, Vol. II, 719-727, 1981.)
• Proceedings of the NATO Advanced Workshop on Problems in Prediction of
Service Life of Building Materials and Components.
7. How are the effects of acid deposition on cement concrete materials best assessed
economically, i.e., loss of service life and repair and replacement frequency?
• The PCA should be able to provide good information on the amount of
cement going into each major use.
• The two studies carried out by Battelle for NBS (on corrosion losses and on
fracture losses in the United States) give some information on economic
losses of construction materials and describe a methodology for analyzing
losses.
8. Response provided by Or. John Morgan, National Park Service, USA.
1. Please list any research on the effects of acid deposition on cement concrete materials that
is in progress or that is being planned.
The National Park Service (NPS) has an interest in mortar, both Portland cement
and lime mortar. There have been discussions concerning laboratory studies to
investigate reaction rates with very dilute acids.
2. Are there existing experimental programs that could incorporate the study of acid
deposition?
NPS has a stone exposure program that may have aspects that could be applied to
concrete. Stone is exposed for periods from three months up to several years.
Runoff is collected and analyzed for cations and anions. Surface recession and
roughness as well as color change is measured. A variety of surface techniques
are used: ion and electron probe, SEM Auger spectrometry etc. Surfaces of
whole specimens and individual grains are analyzed.
3. Does evidence exist for acid deposition damage to cement concrete materials (structures)?
If so, where?
There appears to be no definitive evidence.
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4. How does acid deposition affect cement concrete materials (structures)?
Two types of effects: a, general acid reactions, e.g., HsO* and OH'; b. sulfate
effects - expansion. Also two types of materials: a. cement; b. aggregate in
cement - three main phases: CaS, CsS, CsA. Carbonate aggregate may be
attacked, but may also provide additional buffering.
Will acid deposition affect reinforced cement concrete?
Needs to be investigated. Three possible effects:
1 . Chemical corrosive attack
2. Loss of bond
3. Reaction with
6. Is an experimental program needed to study the effects of acid deposition on cement
concrete materials?
Yes
If so, please make recommendations on the following:
a. Laboratory exposure, field exposure, or survey, etc.
Three stages: 1. Field case studies, 2. Experimental studies (e.g., natural
exposure, runoff, chamber studies), 3. Derivation of damage function.
b. Environmental variables to be measured, etc.
Presumably the standard EPA monitoring covers most possibilities.
c. Specimen composition and size, etc.
Somewhat controlled by aggregate size, and the problem of reinforcement.
d. Damage measurement, etc.
For cement itself, it can be measured as an analog of stone, but the question of
reinforcing adds complexity.
7. How are the effects of acid deposition on cement concrete materials best assessed
economically, i.e., loss of service life and repair and replacement frequency?
If we know a. the total cement production, and b. amount going into roads and
below ground purposes, and can guess c. the amount going into new
construction, then one can estimate an upper limit from the replacement cost.
Some percentage (small-large) of this number can be ascribed to acid rain -
perhaps, try several scenarios.
C. Response provided by Frances P. Bradow, U.S. EPA.
1. Please list any research on the effects of acid deposition on cement concrete materials that
is in progress or that is being planned.
The United Kingdom's building research establishment has long-term exposure studies
of quite a variety of building materials. It would be useful to get access to those data.
3. Does evidence exist for acid deposition damage to cement concrete materials (structures)?
If so, where?
Refer to the Durability of Building Materials bibliography in which articles
relevant to concrete and cement damage are highlighted. (Durability of Building
11
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Materials, Ed. P.J. Sereda, Elsevier Science Publishers B.V.: Amsterdam, The
Netherlands, 2,297-349,1985.)
D. Response provided by Dr. Gunnar Morten Idorn, Consultant, Denmark.
1. Please list any research on the effects of acid deposition on cement concrete materials that
is in progress or that is being planned.
In general, examination of concrete structures with evidence of damage
incorporates (within my field of knowledge) analyses of depth of carbonation.
No specific research is in progress within my regions of activity. I am not aware of
studies of a potential impact of SO2 deposition. I believe that such studies must
face a problem with the abundance of sulphate originally present in concrete.
2. Are there existing experimental programs that could incorporate the study of acid
deposition?
I am not aware of any which could or ought to.
3. Does evidence exist for acid deposition damage to cement concrete materials (structures)?
If so, where?
Not to my knowledge, whereas damage to natural stone with no protective
alkalinity is a considerable problem.
4. How does acid deposition affect cement concrete materials (structures)?
To my knowledge, by carbonation in concrete of insufficient denseness. I have
examined concrete of 137 years' age with only 5-mm carbonation inwards from
the surface (Cement and Concrete Research, 13, pp. 739-743, 1983), and am
satisfied that with available technology, incorporating mineral admixtures,
equally dense and durable concrete can be produced today.
5. Will acid deposition affect reinforced cement concrete?
Carbonation will affect bad concrete, see above.
6. Is an experimental program needed to study the effects of acid deposition on cement
concrete materials?
I do believe that an experimental program would meet with considerable
problems concerning identification of specific acid deposition effects if
reasonably attempting to model natural exposure conditions. Atmospheric
acidity may, though, be more severe in places I have not been dealing with, than
where my experiences originate. To provide advice I would need specific
exposure data of an alarming character.
7. How are the effects of acid deposition on cement concrete materials best assessed
economically, i.e., loss of service life and repair and replacement frequency?
I don't know how the effects, if any, of acid deposition may be assessed
separately, distinguished from other causes of concrete degradation - except by
estimating a "percentage cause" of the total?
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E. Response provided by Dr. Peter J. Sereda, National Research Council, Canada.
"I find the questionnaire difficult to answer because it does not ask the most
important questions, such as:
• What percentage of exposed concrete is at risk?
• What is the rate of deposition of acid as gas and as liquid corresponding to
the various concentrations in the air?
• What is the nature of the distribution of concentrations in urban areas, and
how does it change with height.
• Since concrete is subject to a number of processes of deterioration, acid
deposition is certain to act synergistically and for this reason it is not possible
to determine the effect of one without including the study of all. I suspect
that any process that causes surface cracking will expose the cement-
aggregate bond to attack by acid deposition.
Concrete has a large capacity for neutralizing acid, therefore, only in the cases
where surface texture and appearance is important, concrete may be able to
tolerate many years of acid deposition."
F. Response provided by Dr. T. Skoulikidis, National Technical University of Athens, Greece.
5. Will acid deposition affect reinforced cement concrete?
Yes, refer to T.N. Skoulikidis, Atmospheric Corrosion of Concrete Reinforcements,
Limestones, and Marbles, in Atmospheric Corrosion, Ed. William Ailor, 1982.
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APPENDIX A
AGENDA
Wednesday, December 18,1985
8:30 a.m. Registration
9:00 a.m. Welcome and Opening Remarks
JohnSpence, U.S. EPA
9:15 a.m. Workshop Objectives
JohnSpence, U.S. EPA
9:30 a.m. Survey Results
Larry Kukacka, Brookhaven National Laboratories
10:00 a.m. Break
10:20 a.m. Field and Chamber Exposure Studies - Existing Capabilities
Ed Edneyand David Stiles, Northrop Services, Inc.
11:00 a.m. Development of Material Damage Function
Fred Haynie, U.S. EPA
11.'30 a.m. Lunch
1:00 p.m. Review of Questionnaire
2:45 p.m. Break
3:00 p.m. Workshop Discussion
Geoffrey Frohnsdorff, National Bureau of Standards
5:00 p.m. Adjourn for Dinner
8:00 -10:00 p.m. Discussion
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Thursday, December 19.1985
9:00 a.m. Opening Remarks
Fred Haynie, U.S. EPA
9:15 a.m. Workshop Report
Geoffrey Frohnsdorff, National Bureau of Standards
10:15a.m. Break
10:30 a.m. Resume Discussion
11:30 a.m. Meeting Summary
Fred Haynie, U.S. EPA
12:00 p.m. Adjourn
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APPENDIX B
WORKSHOP PARTICIPANTS
Ms. Frances P. Bradow
U.S. Environmental Protection Agency
Environmental Criteria and
Assessment Office (MD-52)
Research Triangle Park, NC 27711
919-541-3797
Mr. Mario J. Catani
Dur-o-Wal
2215 Sanders Road
Northbrook, IL 60062
312-498-9010
Dr. James R. Clifton
Chairman, ACI Committee 222-
Corrosion of Metals in Concrete
National Bureau of Standards
Building 226, Room B-348
Gaithersburg, MD 20899
301-921-3458
Dr. Edward Edney
Northrop Services, Inc.
P.O. Box12313
Research Triangle Park, NC 27709
919-549-0631
Dr. Geoffrey Frohnsdorff
Chief, Building Materials Division
National Bureau of Standards
Building 226, Room B-368
Gaithersburg, MD 20899
301-921-3704
Mr. Sol Caller
Consultant
118 8th Avenue
Brookhaven, NY 11215
516-676-7811
Mr. Fred Haynie
U.S. Environmental Protection Agency
Atmospheric Sciences
Research Laboratory (MD-84)
Research Triangle Park, NC 27711
919-541-2535
Dr. Larry E. Kukacka
Department of Applied sciences
Brookhaven National Laboratory
Upton, Long Island, NY 11973
516-282-3065
Dr. John Morgan
U.S. Department of the Interior
National Park Service
1100 L Street, NW
Washington, DC 20005
202-343-1055
Dr. James G. Orbison
Assistant Professor
Bucknell University
Civil Engineering Department
Lewisburg, PA 17837
717-524-1182
Mr. Sam Wong
U.S. Army Corps of Engineers
Waterways Experiment Station
P.O. Box 631
Vicksburg, MS 39180
601-542-3273
Mr. John Spence
U.S. Environmental Protection Agency
Atmospheric Sciences
Research Laboratory (MD-84)
Research Triangle Park, NC 27711
919-541-2649
Mr. Frank T. Wagner
N.C. Department of Transportation
P.O. Box25201
Raleigh, NC 27611
919-733-7411
Dr. Ron P. Webster
Department of Applied Sciences
Brookhaven National Laboratory
Upton, Long Island, NY 11973
516-282-3065
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Dr. David A. Whiting
Concrete Materials Research Dept.
Construction Technology Laboratory
Portland Cement Association
5320 Old Orchard Road
Skokie. IL 60077
312-965-7500
Dr. William E.Wilson
U.S. Environmental Protection Agency
Atmospheric Sciences
Research Laboratory (MD-84)
Research Triangle Park, NC 27711
919-541-2551
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APPENDIX C
QUESTIONNAIRE
1. Please list any research on the effects of acid deposition on cement concrete materials that is in
progress or that is being planned.
2. Are there existing experimental programs that could incorporate the study of acid deposition?
3. Does evidence exist for acid deposition damage to cement concrete materials (structures)?
If so, where?
4. How does acid deposition affect cement concrete materials (structures)?
18
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5. Will acid deposition affect reinforced cement concrete?
6. Is an experimental program needed to study the effects of acid deposition on cement concrete
materials?
If so, please make recommendations on the following:
a. Laboratory exposure, field exposure, or survey, etc.
b. Environmental variables to be measured, etc.
c. Specimen composition and size, etc.
d. Damage measurement, etc.
7. How are the effects of acid deposition on cement concrete materials best assessed
economically, i.e., loss of service life and repair and replacement frequency?
19
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