; K264)

Materials and ComponentsTechnology Division

Materials and ComponentsTechnology Division

Materials and ComponentsTechnology Division

Weight Losses of Marble andLimestone Briquettes Exposed to

Outdoor Environments in theEastern United States

by C. A. Youngdahl

Argonne National Laboratory, Argonne, Illinois 60439operated by The University of Chicago

for the United States Department of Energy under Contr act W-31-109-Eng-38

ANL-87-56

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WEIGHT LOSSES OF MARBLE AND LIMESTONE BRIQUETTESEXPOSED TO OUTDOOR ENVIRONMENTSIN THE EASTERN UNITED STATES*

by

C. A. Youngdahl

Materials and Components Technology Division

August 1987

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United StatesGovernment. Neither the United States Government nor any agency thereof, nor any of theiremployees, makes any warranty, express or implied, or assumes any legal liability or responsi-bility for the accuracy, completeness, or usefulness of any information, apparatus, product, orprocess disclosed, or represents that its use would not infringe privately owned rights. Refer-ence herein to any specific commercial product, process, or service by trade name, trademark,manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recom-mendation, or favoring by the United States Government or any agency thereof. The viewsand opinions of authors expressed herein do not necessarily state or reflect those of theUnited States Government or any agency thereof.

*Research sponsored by the U.S. National Park Service for the National AcidPrecipitation Assessment Program.

A major purpose of the Techni-cal Information Center is to providethe broadest dissemination possi-ble of information contained inDOE's Research and DevelopmentReports to business, industry, theacademic community, and federal,state and local governments.

Although a small portion of thisreport is not reproducible, it isbeing made available to expeditethe availability of information on theresearch discussed herein.

TABLE OF CONTENTS

Page

ABSTRACT R....................................................... 1

I. INTRODUCTION .................................................. 1

II. EXPERIMENTAL PROCEDURES....................................... 2

III. RESULTS ....................................................... E

IV. DISCUSSION.............................. ...................... 8

ACKNOWLEDGMENTS ...................................................... 10

REFERENCES........................................................... 11

APPENDICES:

A. DETAILED EXPERIMENTAL PROCEDURES.............................. 12

B. SPECIFICATIONS OF BRIQUETTE EXPOSURES AND FIELD PROCEDURESFROM SITE MANAGEMENI PLAN..................................... 15

C. WEIGHT LOSSES FROM INDIVIDUAL BRIQUETTES...................... 21

iii

LIST OF FIGURES

No. Title Page

1. Stone Briquette for Surface Chemistry Studies..................3

2. Briquette Contoured for Gravimetry............................ 4

3. Typical Briquette Exposure Racks.............. . 5

LIST OF TABLES

No. Title Page

1. Dates of Gravimetric Installatiorns and Removalsat Field Exposure Sites.................... .................... 6

2. Weight Losses and Recession for Two Periodsof Exposure During 1984-1986................................... 7

iv

1

WEIGHT LOSSES OF MARBLE AND LIMESTONE BRIQUETTES

EXPOSED TO OUTDOOR ENVIRONMENTS

IN THE EASTERN UNITED STATES*

by

C. A. Youngdahl

ABSTRACT

Weight losses of marble and limestone samples exposed to

outdoor environments at field sites in the eastern United States

have been monitored in studies initiated in 1984. The proceduresare described, and the results are tabulated and discussed. A

rate of marble loss approximately equivalent to 16 Um of surfacerecession per year was found in North Carolina, and losses of this

order were also observed in New Jersey, New York, and Washington,DC. Limestone weight losses were much higher than for marble in

the first year; loss of extraneous materials from the porous

limestone appeared to be a likely contributor to the overall

loss. The rate of limestone loss diminished in the second year,though it continued to be higher than for marble. Exposures are

continuing in a planned 10-yr program of tests.

I. INTRODUCTION

The effects of acid rain, air pollution, and weathering on Shelburne

Marble and Salem Limestone samples exposed to the outdoor environments of test

sites in the eastern United States are being investigated under the NationalAcid Precipitation Assessment Program (NAPAP).1 The studies of the effects

on stone and other building materials are conducted by several federalagencies cooperating in NAPAP; Argonne National Laboratory (ANL) participates

in the NAPAP effort as a facility of the U.S. Department of Energy. Theinvestigators apply a variety of methods (e.g., gravimetry, surface metrology,

surface chemistry, mineralogy, and rain-runoff chemistry) to measure stone

deterioration. The monitoring of sample weight losses resulting from exposure

to the environments at the test sites is one of several stone research tasks

performed by ANL under the sponsorship of the U.S. National Park Service(NPS), which coordinates all of the stone materials research.

A Site Management Plan for stone field exposures was issued in 1984

by NPS. This plan detailed a projected 10-year schedule of experiments,

described stone procurement and sample fabrication, and contained protocols

*Research sponsored by the U.S. National Park Service for the National Acid

Precipitation Assessment Program.

2

for sample handling and exposures. Stone slabs for rain runoff analyses bythe U.S. Geological Survey (USGS) and briquettes for other investigations,

including ANL's gravimetry, were installed beginning in May 1984 at fourestablished NAPAP test sites located near Raleigh, North Carolina, Chester,

New Jersey, Newcomb, New York, and in Washington, DC. An additional site was

established in Steubenville, Ohio, in 1986; results will be given in a future

report. The sites (designated NC, NJ, NY, DC, and OH, respectively) are

instrumented to record a wide range of environmental parameters.

This topical report details the technical procedures used and data

obtained in the gravimetric tests conducted from May 1984 to September 1986.

The results have been summarized earlier as portions of publications authored

or co-authored by ANL personnel3-5 and are reproduced, along with the

supporting data, in this report.

Preliminary tests of the briquette drying and equilibration procedures

applied prior to weighings were done by ANL, and a protocol for gravimetry,

described in Section II of this report, was developed. The protocol was

accepted in 1984 by the Stone Research Group organized by NPS and in April

1986 by NAPAP peer reviewers.

Sample preparation and gravimetry procedures, summarized in Section II,

are detailed in Appendix A. Apperdi!x B includes (1) the section of the Site

Management Plan specifying the briquettes exposed at these sites for

gravimetry and for measurements of color change, which are done on the same

briquettes; (2) the long-range plan for exposure of gravimetric samples; and

(3) specifications for sample handling by the site operators.

The weighings have been performed on an annual schedule, in accordance

with the Site Management Plan. Averaged weight-loss data from exposed

replicate samples are given in Section III of this report. The weight changes

of individual briquettes are listed in Appendix C.

A discussion of res, .ts ard initial interpretations based on theseresults and on those of companion experiments at the sites is given in Section

IV. Correlations with environmental factors will be elaborated in a future

report when the environmental data pertinent to the subject field tests become

available.

II. SUMMARY OF EXPERIMENTAL PROCEDURES

A. Preparation of Briquettes for Exposure

Briquettes for several studies were cut from stock slabs obtained by

the Stone Research Group, as described in Appendix A. An 80-grit ground

surface was used on marble and a "smooth, planed finish" was used on the upper

surface of limestone briquettes. The dimensions of these briquettes are shownin Fig. 1. The briquettes were water-rinsed, allowed to air-dry, labeled to

3

15

-" 83

51 Fig. 1

Stone Briquette for Surface

K36 Chemistry Studies

1~89

DIMENSIONS: M

preserve information regarding their location and orientation with respect

to the source block, and stored in sealed Ziploc bags for further disposition.

Final shaping of gravimetry briquettes consisted of rounding all edges

and corners by wet grinding marble with 80-grit and limestone with 180-grit

abrasive, to minimize weight loss resulting from handling rather than

environmental exposure. Surface powders were then removed with a softbristle brush under flowing distilled water. Drying and weighing procedures

are described in a separate subsection, below. Figure 2 shows a typical

briquette prepared for gravimetric measurements.

B. Procedure for Briquette Exposures at Field Sites

Three sets of gravimetric samples of each stone type were installed at

each test site and were assigned, respectively, to 1-, 5-, and 10-year periods

of continuous exposure. These sets each consisted of three briquettes.

Additionally, one briquette per stone type was installed at each site for

posterity. Another set of three field control briquettes per stone type was

provided to each site, to be shipped, handled, dried, and weighed with the

test samples but never exposed outdoors, as a test of possible errors caused

by the manipulations. Additional control seta' were retained at the

laboratories for processing and measurement with the field sets as the latterwere received after exposures. The sets of briquettes are detailed in

Appendix B. Handling, installation, and removal of briquettes from the

exposure racks followed specific protocols (Appendix B). The exposure racks,

produced by the National Bureau of Standards (NBS) and illustrated in Fig. 3,

supported the briquettes at a 30* angle to the horizontal, inclined toward

the south. The rack and wedge-shaped sample designs. ensured that the samples

were securely protected from displacement (e.g., by wind), while avoiding

binding forces on specimens and providing a minimum of contact between

specimens and the acrylic rack material.

4

Fig. 2

Briquette Contoured for Gravimetry

C. Exposure Periods

Dates of installation and removal of gravimetric samples at field sites

are shown in Table 1. After the first year of exposure the exposed briquettes

and the field control briquettes were weighed, sent to NBS for colormeasurements, and subsequently returned to the sites for redeployment. The

color test schedule was changed to a biennial cycle after the second yearly

gravimetric measurements, and the briquettes were returned directly to the

exposure sites for redeployment.

D. Briquette Drying and Weighing Procedure at ANL

On receipt from a field site after about one week in transit by ground

carrier, the briquettes were unpacked, removed from the Ziploc bags, and

placed in a 45*C drying oven for nominally one week. The laboratory control

briquettes were subjected to the drying procedure together with the samples

from the field site; i.e., 18 briquettes were present in the oven during the

drying period--three each of marble and limestone exposure samples, plus three

field controls and three laboratory controls of each of the two stone types.

The same laboratory control samples were employed repeatedly as the sets of

samples were received from the sites and dried. At the end of a drying

period, all samples were transferred expeditiously to a balance room and

allowed to equilibrate with air (at 22*C.and <40% relative humidity)

overnight. The samples were thus brought to an effectively reproducible state

with respect to ambient humidity, rather than a state of absolute dryness.

Each sample was then weighed on a Mettler Type B5 C1000 balance with 0.2 mgresolution. Afterwards the briquettes were returned to their individual

Ziploc bags, which were then sealed before the samples were taken from the

balance room.

I

4"

I I~i

!I

Fig. 3. Typical Briquette Exposure Rack

6

Table 1. Dates of Gravimetric Specimen Installations and Removals

at Field Exposure Sites

NC NJ NY DC

Period 1

Install 5-25-84 6-05-84 6-19-84 8-11-84Remove 5-16-85 6-07-85 6-21-85 8-12-85

Period 2

Install 9-16-85 9-16-85 11-20-85* 11-12-85

Remove 6-04-86 6-18-86* 6-26-86 8-14-86

OH

Install 7-17-86

*approximate

III. RESULTS

The results of weighing are summarized in Table 2. Each weight change

shown is the average of three replicate briquettes. For the exposed samples,

the listed weight losses are those that occurred during each of the exposure

periods noted; the total loss for periods 1 and 2 can be obtained by summing

the two individual values. The standard deviations of the observed

gravimetric changes of exposed replicates averaged 5% for marble and 7% for

limestone briquettes. The weight changes shown for the control samples are

the actual differences between the measured weights of these samples at thestart of the program and at the end of each period, averaged over three

samples each. Results for individual briquettes are given in Appendix C.

Weight changes of control samples were negligibly small for marble, but

notable weight losses were found for limestone. The rate of loss fromlaboratory control samples of limestone diminished during several drying

cycles and remained relatively small, although s ignificant. G. Olhoeft(USGS) has suggested to the author that some microcracking may occur within

specimens during the thermal cycle used each time the samples are dried for

weighing, and small amounts of trapped moisture may then be freed and lost;

this release would produce the effect noted. Handling effects are not con-idered to be the major cause of this loss because no loss of stone particles

from laboratory control samples has been noted and repeated weighings duringany given session of weighings show good reproducibility. Further investi-

gations are needed before compensation for the above loss can be made with

confidence: these include study to verify 1) the causes of weight loss fromunexposed limestone briquettes and 2) the effects of ambient humidity present

during drying and equilibration on the ultimate sensitivity of the method for

7

Table 2. Weight Losses and Recession of Stone Briquettes*

for Two Periods of Exposure During 1984-1986

Field LabExposed Briquettes Controls Controls

Expos. Avg. Wt. Loss Prorated Recession Avg. Avg.Time, t Std. Dev., Wt. Loss, Calc., Prorated, Change, Change,

Site mo. g g/yr Um um/yr g g

Marble: Period 1

NC 12 0.2733 t 0.0173 - 16.1 16.1 -0.0022 -0.0013NJ 12 0.4348 f 0.0218 - 25.6 25.6 0.0000 0.0017NY 12 0.2877 t 0.0088 - 16.9 16.9 0.0005 0.0029DC 12 0.3111 0.0044 - 18.3 18.3 0.0009 0.0016

Limestone: Period 1

NC 12 1.5182 t 0.1239 1.5182 - - 0.0402 0.0453NJ 12 1.8050 0.0673 1.8050 - - 0.0315 0.0577NY 12 1.6100 * 0.1054 1.6100 - - 0.0563 0.0878DC 12 1.4210 0.1086 1.4210 - - 0.0699 0.0841

Marble: Period 2

NC 8.5 0.1796 0.0102 - 10.6 14.9 0.0030 0.0033NJ 9 0.3483 0.0239 - 20.5 27.3 0.0007 0.0040NY 7 0.1592 0.0097 - 9.4 16.0 0.0028 0.0044DC 9 0.2389 0.0075 - 14.0 18.7 0.0045 0.0040

Limestone: Period 2

NC 8.5 0.3252 0.0452 0.4591 - - 0.0957 0.1056NJ 9 0.6639 0.0214 0.8852 - - 0.0789 0.1098NY 7 0.2333 0.0156 0.4000 - - 0.0781 0.1124DC 9 0.3995 0.0109 0.5326 - - 0.0984 0.1163

*Each weight change shown was an average from three replicate briquettes, and values forexposed samples were not corrected by control results. At each site, the same sets ofbriquettes were continually employed.

8

limestone.

Because of the foregoing and additional considerations discussed inSection IV, the limestone weight losses were not converted to recession valuesin Table 2. The recession for marble briquettes was calculated as follows:

Recession =Weight loss(Exposure area) x (Stone density)

The exposed area of the upper surface of each briquette was approximately63 cm 2 , and the handbook density of marble is 2.7 g/cm 3 . Measurements onmarble samples showed a density within a few percent of the handbook value.The recession calculation assigns all weight loss to the skyward surfaces;

thus the result is likely to be somewhat greater than the actual value ofsurface recession. (The inclination of the sample surface and the variableangle of rain incidence are disregarded in this approximate calculation.) Theprorated recession (Table 2) was extrapolated with the arbitrary assumption ofuniform weight loss throughout the year. The exposure gaps caused by theannual evaluations have been shortened in the third year in order to reduce

dependence on proration. More rigorous estimates of annual loss will be madewhen environmental data are more readily available and again after the samples

having multiple years of continuous exposure (Appendix B) are weighed.

IV. DISCUSSION

A rate of marble loss approximately equivalent to 16 um of surfacerecession per year for the skyward surface of samples was found after thefirst year of exposure at NC (Table 2). This value was compared in Ref. 5with that found by C. Sciammarella, based on surface recession measured bylaser interferometry on samples exposed in NC simultaneously with thegravimetry briquettes, and with a rate predicted by M. Reddy from analyses of

rain runoff from marble slabs there during a. portion of the first exposureperiod. The results of the three independent methods were in close agreement,

as shown below:

Recession Rate Estimated From

Runoff SurfaceChemistry Metrology Gravimetry

Site (Reddy) (Sciammarella) (Youngdahl)

NC 14 pm/yr 13 pm/yr 16 pm/yr

9

Rates of marble loss during the first period at NJ, NY, and DC were well

within a factor of two of the rate in NC. The prorated rates for the second

period were similar to those of the first at any given site. Comparisons

among sites and exposure periods will be discussed in a future report when

environment. data are more readily available for use in correlations.

The weight losses of limestone briquettes were much larger than those of

marble, as shown in Table 2. However, the results of surface interferometry

and runoff chemistry indicated recession rates for limestone that were similar

to those of marble.5 Thus, the limestone weight loss results are attributed,

in part, to the nonreactive loss of subsurface matter such as residual powders

produced by the prior fabrication processes and perhaps other extraneous

materials originally in the porous material. It is apparent that, as

extraneous materials were gradually flushed from the limestone by rain, the

rate of sample weight loss at each site diminished greatly to a value within a

factor of two of that observed for marble briquettes.

Residues of acidic reactions with the environment are known to be

partially retained by the briquettes, and the contributions of residue weights

to gravimetric results have been considered. Surface chemistry at ANL has

revealed the presence of up to about 200 pg/cm2 of sulfate (the most abundant

product found) on ground-facing surfaces of marble after one year's exposure(and little sulfate accumulation on skyward surfaces); the weight gain

contributed, if sulfate was present as gypsum, was about 300 Pg/cm less

200 Pg/cm2 of calcite consumed to produce this gypsum = 100 pg/cm2 or about

4-5 mg/briquette (approximately 2/3 of the lower surface, as estimated bysurface appearance, retains the product). Up to about 3-4 times this amountof sulfate gain was found for limestone. Thus the contributions to gravi-

metric results by retained product were rather small. This conclusion wasunchanged for Period 2, as sulfation continued at rates generally similar to

those of Period 1 and weight losses continued as detailed in this report. ANL

surface chemistry procedures and results are discussed in Refs. 3, 4, and 8.

The established gravimetric studies are expected to continue through

1994. Additional gravimetry of exposed stone versus sheltered stone sprayed

with clean rain in amounts equivalent to ambient rain has been initiated at a

test site in Steubenville, OH (dry, sheltered samples are present also).

Gravimetry of weathered samples prepared from stone removed from buildings

20-80 years old is also being initiated as part of the continuing work by ANL

under the NAPAP/NPS program.

10

ACKNOWLEDGMENTS

The long-term plan for stone sample exposures at field sites wasdeveloped during 1983-1984 by the Stone Research Group organized by NPS. Thegroup included investigators from the U.S. Environmental Protection Agency andBrookhaven National Laboratory, as well as NBS, ANL, USGS, and NPS. The groupwas under the scientific direction of Dr. Bruce Doe (USGS) in 1984-1985 andDr. John Morgan (USGS) in 1985-1986.

Appreciation for field site operations is due to Curtis Moore (NC),

Paul Fiechter and Scott Begraft (NJ), Raymond Masters (NY), and NPS personnel(DC). The participation of Richard H. Lee (ANL) in laboratory tests of drying

and weighing procedures and in sample preparation for field tests isgratefully acknowledged.

The valuable support and advice of Ms. Susan Sherwood, NPS Project

Officer, and of NAPAP Group VII Chairman Dr. Raymond Herrmann (NPS) in F

1982-1985 and Dr. David Fli:, (Bureau of Mines) in FY 1986 were essenti: to

the effort. Reviews and suggestions by Mr. Randall Fedors (NPS) during the

preparation of this report are also appreciated.

11

REFERENCES

1. National Acid Precipitation Assessment Program Annual Report 1984 to the

President and Congress, Washington, DC, 1985.

2. B. R. Doe, Editor, Acid Rain Site Management Plan for Dimension Stone,

U.S. National Park Service, Preservation Assistance Division,

Washington, DC, 1984.

3. C. A. Youngdahl and B. R. Doe, "Effects of Atmospheric Exposure onRoughening, Recession, and Chemical Alteration of Marble and Limestone

Sample Surfaces in the Eastern United States," in Materials Degradation

Caused by Acid Rain, pp. 266-284, ACS Symposium Series 318, R. Baboian,

Editor, American Chemical Society, Washington, DC, 1986.

4. C. Arthur Youngdahl and Bruce R. Doe, "Dimensional, Chemical, and

Gravimetric Changes in Marble and Limestone Exposed at Field Test Sites of

the National Acid L:ecipitation Assessment Program," in Materials Effects

Task Group VII Peer Review Summaries, pp. 215-225, North Carolina State

University Acid Deposition Program, Raleigh, NC, 1986.

5. Michael M. Reddy and C. Arthur Youngdahl, "Acid Rain and Weathering Damageto Carbonate Building Stone: Results of Material Loss Measurements,"

paper 415, presented at Corrosion '87 Conference, March 9-13, 1987, SanFrancisco, CA, National Assoc. of Corrosion Engineers, Houston, TX, 1987;

republished in Materials Performance, July 1987, pp. 33-36.

6. M. Ross and L. Knab, Selection, Procurement, and Description of Salem

Limestone Samples Used to Study Effects of Acid Rain, NBSIR 84-2905,National Bureau of Standards. Gaithersburg, MD, 1984.

7. M. Ross, Description, Selection, and Procurement of Shelburne Marble Used

to Study Effects of Acid Rai:.,USGS Open-File Report 85-594, United States

Geological Survey, Reston, VA, 1985.

8. C. A. Youngdahl, K. J. Jensen, F. I .lliams, and E. A. Huff, C' .

Alteration of Marble and Limestone L. ples Exposed to Acid Rain 4..d

Weathering in the Eastern United States, ANL-87-57, Xrgonne Nation,'

Laboratory, Argonne, IL, in preparation.

12

APPENDIX A

DEThILED EXPERIMENTAL PROCEDURrS

A. Preparation of Briquettes for Exposure

Shelburne N rble from Vermont, as used, for example, in the Jefferson

Memorial in Wash igton, DC, and Salem Limestone from Indiana, as used in the

National Cathedral in Washington, DC, were obtained6'7 as sample stock

materials by USGS and NBS for the NAPAP/NPS stone research program. Each of

the two stone stocks was selected as a monolithic block and was cut by the

supplier into slabs measuring 610 x 305 x 51 mm, under the supervision of

NAPAP personnel. A surface finish typical of that provided on stone used for

exteriors of buildings was employed on what would become the skyward (top)

surface of each slab and briquette: an 80-grit ground surface was produced onmarble, and a "smooth, planed finish" was used on limestone.

NBS prepared the initial secs of briquettes to be sent to the four field

sites. Selected slabs were :1ed to fabricate briquettes for use in several of

the studies. Nominal dimensions of briquettes are shown in Fig. 1 of the

text. All slabs and briquettes were labeled systematically to preserve

information on their relative locations and orientations in the source blocks:

the sedimentary bedding planes of the stone are parallel to the broad faces of

the briquettes, .nd the most recent sedimentary layers are nearer the upper

faces. After fabrication, the briquettes were rinsed in distilled water,

allowed to air dry, and sealed in Ziploc bags. Briquette' for gravimetry were

sent to ANL for shaping and processing, as described belt The processed

samples were returned by ANL to NBS for color measurements and shipment withother briquettes to the field sites for various tests. Briquettes and slabs

were individually protected by plastic bubble wrap (nom. 1-in.-diameter

bubbles) during transportation by NAPAP personnel to the field sites. The

remainders of the stocks of stone at NBS . sealed in polyethylene wrap and

stored indoors.

In August 1984, these archival and resupply stocks were transferred with

du: :are to ANL 'ith the responsibility for preparation and shipment of

additional briquettes as needed, according to the same procedures. As an

added specification for briquettes :ut from ;labs by ANL, surfaces other thanthe top surface have been given an 80-grit finish (marble) or t 180-grit

finish (limestone) before shipping to test sites. This surf e-finishing

procedure was employed by ANL in the preparation of the sets of gravimetrysamples discussed above and those prepared in 1986 for installation at an

additional test site in Steubenville, Ohio, as well as briquettes supplied by

ANL for other types of tests.

Final shaping of gravimetry briquettes consist d of rounding all edges

I corners by wt-t grinding marble with 80-grit and limestone with 180-grit

...- asive, in order to minimize errors caused by inadvertent damage during

handling at field sites and in the laboratory. After final fabrication, these

samples were rinsed under flowing distilled water (resistivity > 2 Megohm-cm)

13

as surface powder was removed with a soft bristle brush. Drying and weighingprocedures are described in a separate subsection below.

Care has been exercised by NBS and ANL to avoid contamination of samples

by oils and other extraneous substances; but it is recognized that the

limestone, 13-18% of the volume of which consists of interconnected pores, may

contain minor amounts of organic residues as well as some limestone powder

from the formation and fabrication history of the stone. The Stone Research

Group recommended that chemical pre-cleaning, not typically done when

dimension stone is used in buildings and monuments, be avoided in preparation

of samples for exposure. Although it was shown that fingerprint oil is

readily dissolved in water made alkaline by contact with the stone, the

protocol specifies that rubber or vinyl gloves be worn by personnel contacting

samples, in order to prevent any contamination from handling. Concentrations

of impurities that could affect interpretation of exposure results are

determined in briquette bulk materials and surfaces prior to exposure by

analyses at USGS and at ANL8 .

B. Briquette Exposures at Field Sites

Racks for briquette exposures, illustrated in Fig. 3 of the text were

designed to support the samples at a 300 angle to the horizontal, inclined

toward the south. The rack and wedge-shaped (Fig. 1) sample designs ensuredthat the samples were securely protected from displacement (e.g., by wind),

while avoiding binding forces and providing a minimum of contact between

specimens and the acrylic rack material. Racks, produced by NBS, were placed

in semi-rural areas of North Carolina, New Jersey, and New York and inWashington, DC, as described in the Site Management Plan.2 Three sets of

gravimetric samples of each stone type were installed at each test site and

assigned to 1--, 5-, and 10-yr periods, respectively, of continuous exposure.

Each set consisted of three briquettes. Additionally, one briquette per stone

type was installed at each site for posterity. Another set of three field

control briquettes per stone type was provided to each site, to be shipped,

handled, dried, and weighed with the test samples but never exposed outdoors,

as a check for possible errors caused by the manipulations. Other control

sets were retained at the laboratories for processing and measurement with the

field sets as the latter were received after exposures.

Frequent inspections have been made by site operators, who brush away

interfering material such as leaves and bird droppings and who alsoperiodically remove and replace specimens according to the Site Management

Plan. The schedule of annual removal following the different dates when racks

were initially loaded with specimens at the four sites is given in Appendix

B. By protocol, samples are removed under dry conditions between rainfall

events and have been routinely sealed in Ziploc bags, padded, and shipped by

ground transportation to participating laboratories for specific tests; i.e.,

to ANL in the case of sample removals for gravimetry (or for certain other

tests conducted by ANL on separate specimens). The dates given in Appendix B

14

continue to serve as target dates as the program continues, although short-

term deferrals may be made at the discretion of site operators; the protocol

requests deferral if samples in racks are not dry on the scheduled date ofremoval. The actual dates of the subject transactions from May 1984 to thepresent are given in Table 1.

C. Briquette Drying and Weighing Procedures at ANL

On receipt from a field site after about one week in transit by groundcarrier, the briquettes are unpacked, removed from the Ziploc bags, and placedin a 45*C drying oven for nominally one week. This length of time has becomethe standard period of drying. The rather low drying temperature and longtime of drying are employed to avoid subjecting samples to conditions greatlyin excess of those experienced during natural outdoor exposure. The

laboratory control briquettes are subjected to the drying procedure togetherwith the samples from the field site; i.e., there are 18 briquettes present inthe oven during the drying period--three marble and three limestone exposure

samples, plus three field controls and three laboratory controls of each of

the two stone types. The same laboratory control samples are employedrepeatedly as the sets of samples are received from the sites and dried. Atthe end of a drying period, all samples are transferred expeditiously to abalance room and allowed to equilibrate with air (at 220C and <40% relative

humidity) overnight. Each sample is then weighed on a Mettler Type B5 C1000balance that can resolve 0.2 mg. The calibration of the balance is routinely

checked and is effectively invariant. Air temperature, relative humidity, andbarometric pressure are recorded before and after each series of weighings.After the weights are obtained and recorded in a laboratory notebook, thebriquettes are returned to their individual Ziploc bags, which are then sealed

before the samples are taken from the balance room. Samples rest on cleanstainless steel, aluminum, or platinum surfaces during processing, and the

metal is cushioned by an underlayer of resilient material during transfers bycart among laboratory rooms. Personnel wear vinyl gloves during samplehandling. Field briquettes sealed in Ziploc bags are then wrapped in doublelayers of plastic bubble wrap and packed in padded, hard-cased containers forshipping. The procedure described was applied to all sets of briquettes priorto initial installations and for each annual weighing,

15

APPENDIX BSPECIFICATIONS OF BRIQUETTE EXPOSURES AND FIELD PROCEDUP''S

FROM SITE MANAGEMENT PLAN

Table B.1 gives the stone field exposure schedule and Table B.2 gives the

gravimetric briquette selection plan as outlined in Chapter V of Ref. 2.Presented below is the detailed briquette-handling protocol for field exposure

sites, an earlier version of which appeared in Ref. 2.

A. Introduction

Briquette specimens of dimension stone are being tested under outdoor

exposure conditions at sites that are instrumented to record air quality,

precipitation chemistry, and weather data. The exposure effects on the

specimens are analyzed periodically by NAPAP investigators. Changes in

surface chemical composition, physical properties, weight, and color are

monitored. For most of the measurements, the briquette samples are shipped

to participating laboratories. Some specimens are returned to field sites

for further exposure. Because the rate of damage caused by acid rain and

weathering is small, very sensitive methods of analysis are employed. This

protocol is written for exposure site personnel participating in the work to

inform them of the need for great care in sample handling and to specify

procedures to insure the program's success. A separate protocol was provided

for sample-processing personnel in laboratories.

A drawing of the standard briquette sample is given in Fig. 1 of the

text. The upper face (3-1/4 x 2-15/16 in.) of the briquette was given astandard surface finish before the initial exposure in the field, and this

surface is the one of greatest interest to investigators. It is to facegenerally skyward during exposure in its sample rack, except that the plane

of the upper surface of the briquette is purposely inclined 300 to thehorizontal by the slope of the rack; that is, the back edge of the briquette's

upper surface is somewhat higher than the front edge when the sample is in

the rack. The identification code of the sample has been marked on the front

surface with an arrow pointing toward the standard (upper) surface. The front

and back surfaces are not parallel to each other: the taper is present to

help avoid possible dislodging of the sample by high winds (see SampleInstallation, below). During handling, the sample should be gripped (with

the use of rubber or vinyl gloves) at the side surfaces, which are parallel to

each other (Fig. 1). All surfaces of each briquette are of some interest to

investigators; therefore, care should be taken to avoid contamination,

disturbance of any deposits, and physical damage to any surface, edge, or

corner of briquettes during handling.

B. Withdrawal of Briquettes From Racks, Wrapping, and Shipping

1. Samples should be handled with great care. Clean rubber or vinyl

gloves should be worn by site personnel to contact the samples, and only side

16

Table B.1. Stone Field Exposure Program Plan For Sample Installationand Annual Removal

NC NJ NY DC OH

May 1984

June

July

August

September

October

November

December

January 1985

February

March

April

May

June

July

August

September

October

November

December

January 1986

February

March

April

May

June

July

August

September

May 25th - 0 yr

June 5th - 0 yr June 19th - 0 yr

Aug. 11th - 0 yr

May 25th - 1 yr

June 5th - 1 yr June 19th - 1 yr

Aug. 11th - 1 yr

May 25th - 2 yr

June 5th - 2 yr June 19th - 2 yr

July 17th - 0 yr

Aug. 11 - 2 yr

17

Table B.2. Briquette Selection Plan

For Weight Loss/Color Change Measurements*

Exposure SiteType of Briquette LabExposure Color NC NJ NY DC Controls

Shelburne Marble

Annual whitestreak

dark

whitestreakdark

whitestreakdark

Posterity

FieldControlst

H14-17G36-19G26-02

E26-13A33-08136-21

E26-07A33-13G36-21

H14-24G36-10G26-12

A33-14A33-22136-01

H14-03E26-10(36-01

G36-02 G36-03

114-01136-21G36-05

H14-15G36-17G26-22

A33-15A33-06136-06

H14-09E26-16G36-11

G36-04

114-02K36-18G36-06

H14-10G36-22G26-11

A33-19A33-03136-10

H14-19E26-23G36-14

G36-09

114-03K36-20G36-07

H14-18G36-23G26-10

Color onlyC16-21

H36-22K36-22G36-08

Salem Limestone

RU5-13IL4-07GL7-01

HU5-23IL4-18GL7 -06

HU5-06IL4-13GL7-23

IU5-01

GU1-07HU6-04HU5-04

HU5-22IL4-03GL7-18

HU5-09IL4-11GL7--19

HU5-02IL4-21GL7 -10

GL2-19

GU1-12HU6-24HU5-18

HU5-10IL4-19GL7-15

HU5-24IL4-23GL7-14

IL4-08IL4-09GL7-24

GL7-05

GL7-04GL7-11IU4-15

HU1-15RU 1-20CL7-03

Color only"U5-12

*See Ref. 2 for a description of the sample coding system used for field briquettes.

tSite control samples are to be placed indoors at each site on a protected flatsurface, covered with plastic and paper. Annually, when weight loss/color change areremoved from the modules at a site, these simulation samples are to be wrapped,packed, and shipped with the field exposure samples. The control samples will bereturned to the site with the weight-loss/color-change briquettes and will be setindoors on a flat surface and covered as before. This procedure tests degradationin handling.

5-yr

10-yr

Annual

5-yr

10-yr

HU5-05IL4-22GL7-09

HU5-14IL4-06GL7-22

HU5-17IL4-10GL7-02

HL4-20

GU1-06HU6-01HU4-24

Posterity

FieldControlst

18

surfaces should be gripped. No firm contact with the upper surface of samplesshould be made (see Introduction), and no contamination of any sample surfaceduring handling should be allowed.

2. The briquettes must be allowed to dry naturally in the racks beforeremoval. When the briquettes are damp on the date of a scheduled withdrawal,

removals should be deferred by one day if humidity is not high (<50%) and

longer if humidity is high (>50%). When it is very high, conditions are

inappropriate for removals. The effect of dew in contributing moisture to

briquettes should be included in decisions on sufficient dryness: morning

removal would not be favorable if dew had affected the briquettes overnight.This caution is to avoid loss of microgram quantities of surface product from

the stone samples, e.g., to the interior surface of the Ziploc bags, prior toanalysis.

Removal of samples should not be done in haste or under difficult orhazardous conditions. If any such conditions are present on the date of a

scheduled withdrawal, the withdrawal may be delayed slightly at the discretion

of site personnel.

3. Plan and prepare indoors for the work completely before beginning

withdrawals. Consult the schedule provided for identities of samples to be

removed, and locate their rack positions from the placement chart provided.Gather all Ziploc bags (1/briquette), bubble wrap (2/briquette), rubber bands

(3/briquette), and clean gloves needed. Consult Steps 5c-e. If color-change/weight-change samples are to be withdrawn, bag and wrap the six

unexposed briquettes that are stored inside the test station. Remove excess

wrappers from the foam-padded, reusable shipping container provided (retaining

extra wrappers that may be needed to fill void space after loading samples),

place materials needed (and six wrapped samples if applicable) in the

container, and take it along with the notes, a roll of strapping tape, and

scissors to the rack site.

4. Arrange to remove the specified briquette without disturbing other

briquettes or contaminating them with any substance. Samples in the top two

rows of the rack may have to be reached from behind the rack with the use ofa step-platform or other stable support. Convenience should be established

so that care in treatment of samples is facilitated.

5. Remove one of the specified samples and wrap it as follows: (a) whilewearing rubber or vinyl gloves, turn the plastic screw of the specified

location in the rack at least three full turns in the direction that increases

the gap width for removal of the tapered briquette; (b) move the briquetteupslope and clear of its Plexiglass support pegs an only then lift it away

from itf support rods and gently out of the rack, taking care not to scrapethe pegs or screw head against the sample during removal; (c) place the

briquette in a clean Ziploc bag, expel excess air, and seal the bag; (d) wrap

one 12-in. x 12-in. sheet of bubble wrap around the sample, fasten with one

19

rubber band, wrap a similar sheet of the bubble plastic over the first, securewith two crossed rubber bands, and place the wrapped sample in the padded

shipping container; and (e) record any pertinent observations, including notes

on mistakes or accidents that may have affected the briquettes.

6. Repeat the foregoing procedure for the remaining samples of the set

specified, one sample at a time.

7. Fill remaining space in the container with additional sheets of bubble

wrap, and close and latch the container.

8. Apply strapping tape to insure that the container does not come apartwhile being carried or in shipping.

9. Ship the container, marked "Fragile," via expeditious groundtransportation (for example, UPS Ground) to the address indicated on the

schedule provided. (Air shipment must be avoided because partial

depressurization may alter fluid distribution in the porous samples and may

disturb any surface deposits or residues.)

C. Handling of Briquettes Received at Field Sites

The foregoing procedure should be consulted for guidance in sample

handling.

1. On receipt of a shipping container of briquettes from a participating

laboratory, the container should be handled carefully and stored indoors in

an area not subject to flooding or extreme ambient conditions until a time

appropriate for placement of samples into exposure racks. Placement should

not be done in haste, during inclement weather, or under difficult orhazardous conditions.

2. Plan and prepare indoors for the work completely before unpacking the

container. Consult the schedule provided for identities of sampes to beplaced and for their assigned locations. If there are questions, phone Susan

Sherwood, NPS, FTS or area code 202-343-1055.

3. If weight-change/color-change samples are received, open the con-

tainer indoors and locate the six briquettes that are used for monitoring

effects of handling and shipping. These samples, which are not to be ex-

posed to weathering, will be found labeled on the outside sheet of bubble

wrap around each sample. With the use of clean rubber or vinyl gloves, un-

wrap these six briquettes and place the briquettes carefully on a protected,

flat, indoor surface. Record pertinent information and observations.

4. If the container was opened (see Step 3), close and latch the shipping

container, re-apply strapping tape, and transport the container and notes to

the outdoor rack location.

20

5. Open the container, remove one briquette, and remove bubble wrap.Note sample identity and assigned location in rack. Arrange a means of

convenient access to the assigned location without disturbance of other

briquettes on the rack. With the use of clean rubber or vinyl gloves, remove

the briquette from the Ziplo' bag, gripping the sample at the side surfaces

only, and place in the assigned location with care to avoid chipping edges orscraping surfaces on supporting pins or screw head of rack compartment. The

label on the briquette should be facing the downslope direction of the rack,

and the arrow of the labei should be pointing generally skyward. While

avoiding contact with the briquette's upper surface, manually turn the plastic

screw of the compartment until a 1/32-in. gap remains between screw andbriquette. Record any pertinent remarks.

6. Remove the next briquette from the shipping container and repeat theforegoing procedure of unwrapping and placement. Repeat until all briquettes

are properly installed and recorded.

7. Place bags, bubble wrap, and rubber bands in the shipping container

and store the container in a dry location indoors until next use.

21

APPENDIX CWEIGHT LOSSES FROM INDIVIDUAL BRIQUETTES

Weight changes for each annual briquette employed in the gravimetricstudy are shown in Table C.1. A description of the sample coding system usedfor field program briquettes is given in Ref. 2, along with an explanation of

the exposure rack slot layout and numbering system. The weight changes shownfor the exposed briquettes pertain only to the weight loss that occurredduring the indicated exposure period; the total loss can be found by summingthe losses for each period. Weight changes shown for the control briquettesare the differences between the weights measured at the beginning of the

exposure program and at the end of the given period.

R. Fedors has pointed out that for each site and period, the smallestweight loss was almost always observed for briquettes in slots 107 and 207.

Aerodynamic effects on the volume of wind-blown rain received at various

locations within exposure racks are being considered by ANL as possible

contributing causes. Wind deflected up the face of the rack after delivery of

rain may somewhat deflect the rain approaching the higher elevations in the

rack. A cause involving rain, rather than drying, seems required in order to

account for the magnitude of the variation among weight losses of limestone

briquettes during Period 1.

22

Table C.1. Weight Changes (in grams)* Observed in Annual Samples

Expos.Time, Exposed Briquettes Field Controls Lab Controls

Site Mo. Slot Sample Wt. Change Sample # Wt. Change Sample t. Change

NC 12 263207265

NJ 12 263207265

NY 12 263207265

DC 12 263207265

NC 12 163107165

NJ 12 163107165

NY 12 163107165

DC 12 163107165

NC 8.5 263207265

NJ 9 263207265

NY 7 263207265

DC 9 263207265

NC 8.5 163107165

NJ 9 163107165

NY 7 163107165

DC 9 163107165

H14-17G36-19G26-02

H14-24G36-10G26-12

H14-15G36-17G26-22

H14-10G36-22G26-11

HUS-05IL4-22GL7-09

HUS-13IL4-07GL7-01

HU5-22IL4-03GL7-18

HUS-101L4-19GL7-15

H14-17G36-19G26-02

H14-24G36-10G26-12

H14-15G36-17C'26-22

114-10G36-22G26-11

HUS-05IL4-22GL7-09

HU5-13IL4-07GL7-01

HU5-22IL4-03GL7-18

HU5-101L4-19GL7-15

Marble: Period I

0.2915 G36-050.2500 H36-210.2785 114-01

0.4520 114-020.4040 K36-180.4483 G36-06

0.2908 114-030.2757 K36-200.2965 G36-07

0.3172 H36-220.3091 K36-220.3070 G36-08

Limestone: Period 1

1.5674 HU6-011.3480 GU1-061.6392 HU4-24

1.8482 GU1-071.7099 HU6-041.8569 HU5-04

1.5769 GUI-121.5006 HU6-241.7524 HU5-18

1.4169 GL7-041.2900 GL7-111.5560 IU4-15

Marble: Period 2

0.1889 G36-050.1654 H36-210.1846 114-01

0.3779 114-020.3194 K36-180.3476 G36-06

0.1668 114-030.1455 K36-200.1653 G36-07

0.2493 H36-220.2319 K36-220.2355 G36-08

Limestone: Period 2

0.3828 HU6-010.2723 GUI-060.3204 HU4-24

0.6636 GU1-070.6379 HU6-040.6903 HU5-04

0.2452 GU1-120.2112 HU6-240.2434 HU5-18

0.4014 GL7-040.3853 GL7-110.4117 IU4-15

*A negative sign denotes a weight increase.

-0.0016-0.0026-0.0025

0.00020.0000

-0.0002

0.0012-0.0002

0.0004

0.00130.00090.0005

0.03230.05010.0383

0.04360.02940.0215

0.06510.04680.0571

0.06670.07030.0726

0.00330.00340.0024

0.00190.0005

-0.0003

0.00290.00280.0026

0.00670.00390.0030

0.08690.11070.0895

0.09440.07630.0660

0.09010.06390.0803

0.09360.09900.1026

G26-10G36-23H14-18

H14-18G36-23G26-10

H14-18G36-23G26-10

H14-18G36-23G26-10

HU1-15GL7-03HU1-20

HU1-15HU1-20GL7-03

HU1-15HU1-20GL7-03

HU1-15KU1-20GL7-03

G26-10G36-23H14-18

H14-18036-23G26-10

H14-18G36-23G26-10

H14-18G36-23G26-10

HU1-15GL7-03HU1-20

GL7-03HUl-15HUL-20

GL7-03HU1-15HU1-20

GL7-03HU1-15HU1-20

-0.0014-0.0006-0.0019

0.00050.00260.0021

0.00210.00390.0027

0.00080.00250.0016

0.04410.05400.0378

0.05770.04840.0671

0.08900.07890.0955

0.08530.07570.0914

0.00330.00430.0023

0.00330.00490.0039

0.00330.00560.0044

0.00280.00520.0040

0.10880.11200.0960

0.11580.11310.1004

0.11830.11470.1042

0. 12270.12020.1061

23

Distribution for ANL- 7-56

Internal:

R. DaltonH. DruckerP. HessD. KuppermanA. C. RaptisD. Schmalzer

J. ShannonE. StefanskiD. StreetsC. TillR. WeeksM. Wesley

J. WozniakA. Youngdahl (7)

ANL Patent Dept.ANL Contract FileANL LibrariesTIS (3)

External:

DOE-TIC (10)DOE Chicago Operations Office:

ManagerMaterials and Comp'nents Tecl ; Division Review Committe:

P. AlexanderS. J. GreenR. A. GreenkornL. J. JardineC. LiR. E. SchollP. G. Shewmon

National Park Service:L. NelsonJ. RogersS. Sherwood (10)

National Acid Precipitation Assessment Program:Executive Director of Research

United States Geological Survey:P. BaedeckerM. KingstonJ. MorganV. MossottiR. PickeringM. ReddyM. RossE. Spiker

Colorado School of Mines:D. Langmuir