Pavers from Recycled Glass

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I Pavers from Recycled Glass

I A Model for Small-Scale I Pressed Glass Manufacturing \ \ \ I PAVERS FROM RECYCLED GLASS

A model for small-scale pressed glass manufacturing

FINAL REPORT

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THE CLEAN WASHINGTON CENTER A division of the Department of Trade & Economic Development 2001 Sixth Avenue, Suite 2700 Seattle, WA 98121

July 7, 1993

Laboratory analysis by

The Applied Technology Development Center Westem Washington University Bellingham, WA 98225

This recycled paper is recyclable

REPORT NUMBER: B 16

This report describes some of the operating characteristics, dimensions, and output of a small-scale production system for manufacturing paving bricks from recycled glass. Paving bricks were chosen for this project because a product was sought which could be manufactured inexpensively in a single style, has a large existing market, and has the potential to absorb a large quantity of recycled material without the addition of quantities of virgin batch modifiers.

Working with molten glass is usually considered to be as much of an art as a science, and all of the small-scale glass production businesses in the Northwest of which the author is aware are art glass production houses. One of the goals of this project was to gain knowledge of the potential for creating small, economically- viable pressed glass manufacturing operations within communities, using indigenous labor and materials, making a product which could be manufactured by workers with no background in glass art.

In performing business assistance, attempting to stimulate alternative markets for recycled glass, the author has often felt that it would be useful to have, but he has not found, a short, straightforward document explaining the difficulties and opportunities for glass melting applications. It is hoped that this document will help to fill that function.

The author wishes to thank Bill Sargent of Hot Stuff Glass for his heroic expenditure of time and money to make this project work. No public money was paid to private companies during this project. The long term goal of this project, and this department, is to advise, accumulate, and disseminate information which will enable private companies like Hot Stuff to use recycled materials as resources for profitable enterprise. 2 ll=wmJa To qualify as a paving material, it was important to prove that the physical characteristics of the glass bricks would meet or exceed standards for a generally accepted paving material. The bricks were tested against American National Standards Institute Specifications for Ceramic Tile, ANSI A1 37.1-1988.

Specifically, section 5.3 of the standard named above pertains to unglazed ceramic paver tile. Visual and dimensional specifications were not applied because those will be a function of the repeatability of the final production process. Rather, this project was intended to investigate the fitness for use of remelted bottle glass in terms of its physical performance. The tests performed were: 1) Coefficient of friction per ASTM C 1028 2) Bond strength per ASTM C 482 3) Breaking strength per ASTM C 648 4) Abrasive hardness per ASTM C 501 The Applied Technology Development Center of Western Washington University performed the tests.

The glass pavers manufactured for this project were 4" x 8". the same length and width as standard paving bricks. Thicknesses of both 1" and 1 1/2 were made. A 1 112" thick glass brick weighs about four pounds. The bricks are designed to be marketed as a highlight or detail in areas paved with standard clay brick.

Glass bricks were made with three textures, two-dimensional serrated, random, and smooth-surfaced. The serrated pattern is a uniform grid, with a mold cast from the cover of a common fluorescent light fixture. The random pattern is a swirled texture. The smooth-surfaced bricks were poured into the mold and not pressed, but rather allowed to settle with gravity. Samples in all styles can be seen by contacting Bob Kirby, business assistance specialist at the Clean Washington Center.

Since samples have been shown in the community, some interest has been shown in using the bricks as translucent panels in vertical applications. This project tested strength characteristics for paving applications, not window applications. Which is not to say that, subjectively, the bricks would not be functional and attractive in vertical applications where agency approval was not required. 3

Some of the untextured bricks have been broken up, tumbled with abrasives, and used with marble rubble in interesting floor samples. All of the bricks made to date have been melted from clear bottle glass, with no additives or fluxes. The product has an amber-gray tint which many find appealing.

Some of the untextured bricks have also been sandblasted. Another potential market may exist in sandblasting logos or images on bricks and selling them as promotional, award, or decorative items.

-The production system described here falls under the category of "pressed glass." Pressed glass involves creating molten glass from virgin materials or remelted old glass, then pouring the glass into a mold and pressing while still hot and malleable into a desired shape. The concept is easy, but implementation can be difficult.

For a production rather than a one-time artwork product, the physical parameters which affect the qualities of the finished product must be understood and well enough replicatable to manufacture products within acceptable tolerances. The strategy of this project was to perform iterative rounds of testing in order to optimize the production process for aesthetics, strength, and operations.

Hot Stuff Glass uses a 200 pound natural gas-fired pot furnace into which the recycled glass is loaded for melting. A pot furnace is a refractory furnace which contains an open crucible made from fused crystalline silica. A natural gas burner maintains the crucible at a temperature adequate for melting glass.

These are the important parameters for the production cycle: Melting time Melting temp Pour temp Anneal time and temp profile.

Meltina In the first round of tests, glass crushed in a Vitreous Environmental GlassBlaster and screened to 16 mesh minus was used. The Vitreous equipment is interesting 4 because when glass is crushed to the consistency of coarse sand, most of the contaminants (paper and plastic labels and aluminum caps) do not crush as efficiently as glass. Therefore, following crushing, the glass can be passed through a screen which passes most of the glass but retains the contaminants.

In the glass melting process, organic contaminants such as plastic and paper burn off below 1000° F, leaving little if any detectable residue. If they are initially present at levels of only a few percent, the final product is not effected. They do, however, create emissions as they burn off which can be a problem both in the working space and, in larger facilities, in emissions air quality.

In the first round of tests, the glass melted from finely ground bottles foamed, threatening the integrity of the furnace, before collapsing into the molten state. For this reason, glass crushed into about 1" diameter pieces was used for the other tests. More investigation needs to be done to determine whether the foaming problem can be overcome.

Glass is loaded into the furnace at the melting temperature and remains there to refine for the melting time. Melting and refining was accomplished in this test by holding the glass at 240OOF for about 12 hours. Pouring was done at the same temperature, after the glass was determined to have sufficient viscosity to allow adequate control of pouring. For these tests, pouring was performed by ladling molten glass into a mold. Consistency was obtained in the thickness of the brick through the judgement of the pourer.

Larger automated pressed glass manufacturing systems use continuous furnaces and gob feeders. The continuous furnace has a long, shallow melting trough into which unmelted batch materials are introduced at one end, and flow through as they melt to the other end, where molten glass is automatically metered directly out of the furnace in controlled "gobs" which fall into molds, usually on an indexing table where automated pressing is performed (this is obviously a simplistic description - many books have been written on the intricacies of continuous glass furnaces). 5 tdQl& The molds were made from aluminum bronze scavenged from old glass bottle molds. A common practice in the industry is to make test molds from graphite, which will allow only a limited number of pours before wearing out. Once the - design and practicality of the product has been proven, permanent molds are made from aluminum bronze or cast iron. Permanent molds require extensive casting ~~ and machining, and can cost from $2000 to $5000 per set.

The taper of the molds made for this project allow brick thicknesses of 1/2" to 1 1/2" to be manufactured without causing the molds to bind during pressing.

Illumss After ladling the glass into the mold, while the glass is still malleable, the top of the mold is brought down and the glass is pressed into the mold shape. Traditional glass pressing equipment involved the use of a lever-operated press which brought together two halves of a mold. Three or four person production teams were required to gather the ball of glass, pour it into the mold, press, remove the pressed glass, swab the mold, and carry the glass to the annealer.

With a simple shape and dedicated equipment, however, it may be possible to build equipment designed to be operated by two people, with a mechanism for easily dumping the pressed piece out of the mold.

For this project, Hot Stuff Glass built a press actuated by a pneumatic cylinder which lowers the textured top of the mold into the cavity of the bottom, pressing the glass as it cools. The mold top and bottom were slightly tapered to prevent wedging. As soon as the glass brick hardens enough to retain its shape, the bottom of the mold is rotated on a set of pillow bearings, dumping the brick out of the mold. A sketch of the press is shown in figure 1. Construction of the pneumatic press and the molds consumed a large portion of the contract time for this study, and was undertaken at the time and expense of Hot Stuff Glass. nAir cylinder

Bearing

figure 1. Hot Stuff custom glass press. As the machine was used, it was found that heat conducted to the bearings and legs distorted the frame enough to limit the speed of production. In large-scale production, molds contain jackets through which coolant can be pumped to maintain proper working temperatures. With this machine for a model and to work out the bugs, the machine builder has ideas for improvements on future designs. production Because melting time for the glass is at least 12 hours, Hot Stuff's daily production is limited to the capacity of its furnace. For the glass bricks, that means about 50 pieces per day. Because of the manual nature of the production, and dependent on the skill of the workers, it can be assumed that no more than 80% of production will be of saleable quality. 7

Annealina Molten glass normally cools from the outside in. As it cools the viscosity increases as it approaches a state of practical infinite viscosity at room temperature. Being an amorphous substance, there are no defined crystalline or state interfaces. Rather, areas of tension and compression are produced by temperature gradients interacting with viscosity characteristics of the material.

If molten glass is cooled too quickly, the outer surface will reach a point of solidity earlier than the inside. As the inside cools it also shrinks. If the outside is already solid, a condition is created where the inside is under tension from pulling in as it cools, while the outside is under compression from being pulled into a smaller volume than it would occupy with no stress at that temperature. If the outside is cooled too quickly, the glass object will literally tear itself apart.

More disturbing from a production point of view, if permanent strain below the failure point is set up by cooling a glass object too quickly, the object can appear to be stable, but at some time in the future a small jolt may cause the strain to overcome the integrity of the piece, causing fault lines to appear inside. This balance of internal stress and strain has been used historically to create safety devices which fail at a predictable tension.

The permanent stress problem can be overcome by cooling at a slow enough rate that temperature gradients are low and internal and external stresses are constantly relieved by homogeneous physical changes in the glass. In larger manufacturing operations, continuous annealers , or "tunnel lehrs," are used in which glass objects are moved through a temperature profile on a continuous belt. In small operations, annealing must be done in a closed temperature-controlled vessel which is too expensive to dedicate to one piece for a prolonged length of time. Therefore, some compromise must be reached between ideal and practical annealing profiles.

Thicker glass objects and those with somewhat indeterminate physical properties are more difficult to anneal than thinner, more well-defined pieces. Recycled bottle glass contains containers of all types, both domestic and foreign. Therefore, there is some level of indeterminacy in its physical characteristics as compared with 8 glass batched from well-known virgin material. The bricks made for this project were also very thick compared to most common glass objects.

Finding workable annealing parameters was, and continues to be, one of the biggest challenges of this project. For soda-lime glass sheet 1 1/2thick, Tooley gives the following annealing time and temperature profile: Temperature range Time (minutes) Rate 934 131 934-924 18 924-914 15 914-904 12 904-894 9.5 894-884 I 884-100 11O0F/hour

The table above (Tooley, page 808) translates into 208 minutes, or almost 4 hours of carefully controlled cooling, followed by 6 hours of less critical cooling. This gives an indication of the complexity of the annealing process.

In a small shop dealing with recycled glass, empirical information is as important as theory, so "slump tests" were performed to determine the annealing parameters. In slumping, a sample is placed in the annealer, and the highest temperature is sought where the glass has sufficient viscosity to support itself without "slumping" (something the author frequently does on Friday afternoon). The annealing point is then set at about 100°F below the slump point, a temperature where the pieces are strong enough to stand, but still soft enough to allow internal stresses to relieve themselves.

It was found in the test production runs that the mass of the mold and its changing temperature throughout the day created material consistency problems. Since the

mold was colder than the molten glass, although it was heated with a torch during ~ production, contact with the mold was causing the outside of the bricks to cool too quickly. To compensate for this problem, Hot Stuff built a small "flash annealer," which was maintained at 1200°F, and into which newly poured bricks were placed for several minutes to stabilize the outside and inside temperatures before placing the bricks into the large annealer. 9

The annealing profile that was found to work the best was to place 1" bricks into the large annealing lehr for a minimum of 2 hours at 1010OF. When the last 1" bricks made from the furnace load had been in the annealer for a minimum of 2 hours, the annealer was cooled at a rate of 2OOOF per hour. A rule of thumb in the industry calls tor one hour of annealing time per 114" depth from the side exposed to the annealing lehr. Following this empirical procedure resulted in the most consistent quality of production.

sical characteristrcs The appendix contains the lab reports from Western Washington University. When this project was undertaken, it was not known how remelted bottle glass would perform as a paving material. Bottle glass is, after all, softer than window glass and has the reputation for being "slick as glass." Glass artists are under the impression that bottle glass gets harder each time it is remelted, as the fluxing agents "burn off." It has not been determined whether this is, indeed, the case, or just an "urban legend."

BreakinutmUh The breaking strengths for the test bricks were as follows: nominal thickness mean std dev test 1 1 112" 4576# 1255# test 2 1" 3092# 1285# ANSi A137.1-1988 section 5.3.1.3.3 requires a minimum of 250 pound breaking strength for ceramic paving material..lt was not surprising that glass is much stronger than ceramic material in breaking strength. This may be an installation advantage for pavers, since attaining a uniform underlayment is less critical for paving materials whose capacity far exceed expected loads.

Abrasive hardness represents the "wearability" of the material. It is a surface test, so thickness should be irrelevant. nominal thickness mean std dev test 1 1 112 74.1 gm 6.4gm

test 2 1" 57.1 gm 13.2 gm 10

ANSI A137.1-1988 section 5.3.1.3.4 requires an abrasive index of 50 for a natural clay paver. All samples except one exceeded an index of 50. Therefore, the glass pavers should meet minimum wear requirements for brick paver applications.

-In the first sample run, the test lab used a polyurethane adhesive which demonstrated an excellent bond to adhesive failure with the glass bricks. See the appendix for a description.

For the second run, it was decided to try a Portland cement mixture which is commonly used with glass block construction. Problems were encountered finding an appropriate mortar mix. See the appendix for a description.

More mortar tests will be run, and this report will be amended to report future results. .. .. Coefflclent of film Coefficient of friction (COF) tests were run for both wet and dry surfaces. The bricks tested had the serrated surface texture. The results, expressed as Fx, were as follows: dry (FD) wet FW) test 1 .633 .475 test 2 ,736 .470 ANSI A137.1-1988 section 5.3.1.2.9 specifies that the COF shall be as agreed to between the buyer and seller. Brungraber and Adler found a static COF for terrazzo of .25 to .35, and for synthetic marble of .15 to .2, although they comment that the inconsistencies of COF testing are such that comparisons should only be made relative to the exact same test setup.

PwinduStU During the course of the project the possibility of encouraging the creation of a number of small-scale manufacturing operations throughout the state, each with different molds and styles, was discussed. In this way, a wide variety of basic materials could be made in a number of small-scale facilities, possibly marketed by a producers' cooperative. "Okanogan Pavers," "Gray's Harbor Pavers," and 11

"Whatcom Pavers" would each have a distinctive style and could share production insights and pool purchasing power at regular meetings.

Facilities could be designed as turnkey operations and set up with the insights of Bill Sargent, owner of Hot Stuff. A manual of standard operating procedures could be created to make it unnecessary for the workers to be glass artists.

The following list gives some indication of the scale of capital costs for such a two- person operation: 800 pound pot furnace w/controls $120,000 glass press 20,000 molds 20,000 annealing lehr 4,000 misc. equipment l.!uNQ total capital cost $1 80,000 annual cost amortized over 5 years at 9% $46,000 and annual operating costs: rent 3000 square feet $4,000 natural gas 5,000 electricity 3,000 replacement crucible 1,000 other misc. parts 1,000 consumables 10,000 contingency and other organization expense 20,000 two workers, $30,000 each total compensation 60,000 amortization expense from above ilfa2Q estimated annual cost $1 50,000 Two workers with this equipment could make about 150 pavers per day, or about 35,000 per year. Therefore, the pavers would need to sell for about $5 each, f.0.b. factory. Such an installation would consume the recycled glass from about 5000 people.

r facw.. Another possible strategy would be to use the insight and knowledge gained in this project to scale Hot Stuff Glass up to a larger manufacturing facility. Data have not 12 been gathered, but informal information gathering has given a sense that the equipment to establish a 2-4 ton per day continuous furnace operation with indexing molds and automatic gob feed would cost on the order of one million dollars. flext steDS More work needs to be done to make the Hot Stuff Glass glass paver operation into a viable, replicatable model. A number of technical details of manufacture need to be worked out through experience and with the advice of glass production experts. Now that the product can be made, marketing can be done to get a sense of the saleability of the product. The product is initially being promoted to architects for specific jobs, especially those where interest has been expressed in using recycled products. If sufficient interest is demonstrated, more traditional lines of distribution will be investigated.

The Clean Washington Center will begin to investigate the level of interest throughout the state in developing small businesses as described above. The idea of creating producer cooperatives to both manufacture and distribute the products may be attractive to pursue. Anyone with additional insights and information is welcome to call Bob Kirby, business assistance specialist, at (206)389-2549.

Functional biblioarat, hy Brungraber, R. J., and Adler, S. C., "Technical support for a slip-resistance standard," Walkway Surfaces, Measurement of Slip Resistance, ASTM STP 649, ASTM, 1978, pp. 40-48.

-. -. Although it is oriented large-scale manufacturing, this magazine offers many practical insights into small-scale production as well.

Tooley, Dr. Fay V., The H- , Ashlee Publishing Co., Inc., N. Y., N. Y. 1984. ASTM TESTING OF RECYCLED GLASS PAVING BRICKS

as performed by Western Washington University Engineering Technology Department Applied Technology Development Center

Performed in conjunction with HOT STUFF GLASS and Washington State Department of Trade and Economic Development Clean Washington Center ASTM DESIGNATION C-482 BOND STRENGTH

Sample Run #1 Scope This test method covers the determination of the ability of recycled glass brick pavers to be bonded to selected adhesives. A small portion of the adhesive spectrum has been tested to provide a range of choices. Apparatus Five frame type molds were initially constructed following dimensions in the standard. Wood with a veneer finish was chosen in lieu of brass or other heavy metal. In addition, the support fixture was constructed using 1/2 aluminum with minor dimension modifications for base support. A key was constructed according to the standard from 1/8" aluminum plate and a Tinnius/Olsen tensile machine was used to apply the force. Test Sample The sample number of five (5) and the sample size was 4x 4. Summary of Test Method This method consisted of the bonding of a glass brick paver tile to a polyurethane adhesive (Sikaflexo) bed. Portland cement was not used as it is a corrosive to the glass paver. After an inadequate cure of the polyurethane bed, we changed to a plywood bed and an adhesive thickness of 1/8". After a 24 hr. cure at 70' Fahrenheit, a load was applied as per the standard using a Tinnius/Olsen tensile tester. The paver did not separate from the molded bed due to the elstic characteristics of the adhesive. Results Sample #1 Sample #2 Sample #3 Sample #4 Sample #5 Overall Dimension 3.43 X 3.92 3.95 X 3.92 3.93 X 3.95 3.94 X 3.95 3.92 X 3.95

Bonded Surface 13.89 sq. in. 14.01 sq. in. 14.04 sq. in. 14.01 sq. in. 14.00 sq. in. Force (lbs) 573 560 541 585 581 Bond Strength (psi) 41.26 40.0 38.5 41.5 41.05 Elongation .958 in. ,980 in. .960 in. .925 in. .940 in.

Bond Strength

42 -

Force (psi)

I Sample Sample Sample Sample Sample #1 #2 #3 #4 #5

2 ASTM DESIGNATION C-482 BOND STRENGTH SAMPLE RUN #2

Information was received from Clean Washington Center regarding a mortar mix currently used with the product, PC GlassBlock@. Pittsburgh Coming, the manufacturer, was consulted as to further physical properties of the mortar's application to their product. The mix was prepared according to their specifications and consisted of:

1 part Portland Cement 1/2 part Lime 4 parts Sand

Mixed to a 'mashed potato' consistency, it was applied to wooden blocks which were substituted for the full mortar block. After 4 days of curing, the samples showed little bonding quality to the wood or glass. It was decided not to continue any further with this particular mortar mix,

Note of information:

During a telephone conversation with Pittsburgh Coming regarding this mortar mix, we were told they use a PVB (Polyvinylbuterol) coating on their glass blocks for adhesion and creep control. The glass paver we tested has no surface modification and is an area that should be explored further.

3 ASTM DESIGNATION C-482 BOND STRENGTH THIRD SAMPLE RUN Local research revealed a source for a mortar mix known as 'glass block mortar'. This was applied to the glass pavers as described above or what is known in the industry as a thin set.

4 ASTM DESIGNATION C-501 ABRASIVE HARDNESS

Sample run #1 Scope This test method covers the establishment of an abrasive wear index by determination of the loss of weight resulting from abrasion of recycled glass brick pavers. Apparatus The apparatus used the recommended Taber Abrasion Tester, Model 510 using H-22 abrasive wheels. Test Sample The sample size was 4x 4x 0.50” and the number of three (3)was used due to inadequate supply. Original cast size of 4x 4x1.50 was too thick for the abraser unit and was reduced to 0.50. Summary of Test Method The sample was secured to the abraser plate using doublesided adhesive tape. Testing was done on the textured side and evaluated according to the standard. Results

Sue (in) Initial Final Weight IW LxWxH Weight Weight Difference (gm) (gm) (gm) (gm) Sample #1 3.890 x 3.750 x .895 529.91 528.83 1.08 81.48 Sample #2 4.000 x 3.895 x .850 482.41 481.15 1.26 69.84 Sample #3 3.940 x 3.875 x .875 517.30 516.06 1.24 70.97

The mean average for Iw was 74.96 gm.

Abrasive Hardness

Weightloss 75 (sm) 70 65 60 Sample Sample Sample #1 #2 #3

5 ASTM DESIGNATION C-501 ABRASIVE HARDNESS Sample Run #2 Scope This test method covers the establishment of an abrasive wear index by determination of the loss of weight resulting from abrasion of recycled glass brick pavers. Apparatus The apparatus used the recommended Taber Abrasion Tester, Model 510 using H-22 abrasive wheels. Test Sample The average sample size was 4"x 4x 0.814 and the number of samples was four (4). Summary of Test Method The sample was secured to the abraser plate using double-sided adhesive tape. Testing was done on the textured side and evaluated according to the standard. Results Size (in) Initial Final Weight Iw LxWxH Weight Weight Difference (gm) (gm) (gm) (gm) Sample #1 3.864 x 3.939 x .906 533.65 531.44 2.21 39.82 Sample #2 3.838 x 3.942 x .821 475.85 474.21 1.64 53.66 Sample #3 3.880 x 3.935 x .759 437.23 435.91 1.31 67.18 Sample #4 3.888 x 3.937 x 773 463.39 462.09 1.30 67.69 ' The mean average for Iw was 57.08 gm.

Abrasive Hardness

Weight loss 40 (am) 30 20 "IrLu_100 Samle SamDle Samde Samde #1 #2 #3 #4

6 ASTM DESIGNATION C-648 BREAKING STRENGTH

Sample Run #1 Scope This test method covers the determination of the breaking strength of recycled glass brick pavers having a facial area of at least 1 in.2 Apparatus The specimen support was created as per the standard. Test Sample The sample number was ten (10) and the sample size was approximately 4x4". Summary of Test Method Physical measurements were obtained prior to the test. Samples were then placed on the fixture and tested according to the standard. A Tinnius/Olsen tensile testing machine was used to apply and measure force.

Results Sample Sample Sample Sample Sample Sample Sample Sample #1 #2 #3 w4 #5 #6 #7 #8 Force 3950 4170 4490 2570 6080 4510 6590 4250

Breaking Strength 7000r

5000 4000 Force (Ibs) 3000 2000

1000

0 Sample Sample Sample Sample Sample Sample Sample Sample #1 #2 #3 #4 #5 #6 #7 L#8

7 ASTM DESIGNATION C-648 BREAKING STRENGTH Sample Run #2

Test Sample The sample number was ten (10) and the sample size was approximately 4x4 x 1" . Results

Sample # #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 Force(1bs) 3670 4000 5270 4110 3150 2420 3240 1290 2690 1080

The mean breaking strength was 3092#.

Breaking Strength 60005ooot r

Fwce

Sample#3 Sample Sample Samle Samle Samde Samde Samle Samle %"e #1 #2 I #4 #5 #6 #7 #8 #9 #lo

8 ASTM DESIGNATION C-1028 COEFFICIENT OF FRICTION Sample Run #1 Scope This test method covers the measurement of static coefficient of friction of recycled glass brick pavers. Apparatus The heel assembly was constructed according to the standard. The forces were measured in lbs. by a Chatillon hand spring scale. The spring was checked for calibration against the Tinnius/Olsen tensile testing machine. Test Sample The sample number was three (3)as required by the standard. A fourth was used as a reference point for control purposes. Summary of Test Method Physical measurements were obtained prior to the test. Samples were then tested according to the standard.

Results: Wet Calibration Test FD= 0.475 Size (in.) Pull #1 Pull #2 Pull #3 Pull #4 Reference 3.85 x 3.95 x 1.68 18 18 16.5 17.5 Sample #1 4.04 x 3.95 x 1.67 14.5 15 13.5 15.5 Sample #2 3.87 x 3.90 x 1.72 19.5 22 17.5 20 Sample #3 3.92 x 3.95 x 1.77 14 15 19 16.5

Wet Calibration

25r

9 Results: Dry Calibration Test FD= 0.633 Size Pull #1 Pull #2 Pull #3 Pull #4 Reference 3.85 x 3.95 x 1.68 23 19 25 25 Sample #1 4.04 x 3.95 x 1.67 18 16.5 18 20 Sample #2 3.87 x 3.90 x 1.72 21 20 19.5 20.5 Sample #3 3.92 x 3.95 x 1.77 18.5 18 20 18.5

Cabration

25 r

" Pull #1 Pull #2 Pull #3 Pull #4

10 &TM DESIGNATION C-1028 COEFFICIENT OF FRICTION

Sample Run #2

Results: Wet Calibration Test Fw= 0.470 (using mean XW = 0.136) Size (in.) Pull #1 Pull #2 Pull #3 Pull #4 Sample #1 3.91 x 3.94 x .98 18 18 16.5 17.5 Sample #2 3.81 x 3.95 x .99 14.5 15 13.5 15.5 Sample #3 3.971 x 3.95 x 1.00 19.5 22 17.5 20

Wet Calibration

25r

Results: Dry Calibration Test FD= 0.736 (using mean X~=0.368) Size Pull #1 Pull #2 Pull #3 Pull #4 Sample #1 4.04 x 3.95 x 1.67 18 16.5 18 20 Sample #2 3.87 x 3.90 x 1.72 21 20 19.5 20.5 Sample #3 3.92 x 3.95 x 1.77 18.5 18 20 18.5

Dry Calibration

25 r