USF Libraries
USF Digital Collections

Stabilization of marginal soils using recycled materials

MISSING IMAGE

Material Information

Title:
Stabilization of marginal soils using recycled materials
Physical Description:
Book
Language:
English
Creator:
Carreon, Delfin G
Publisher:
University of South Florida
Place of Publication:
Tampa, Fla
Publication Date:

Subjects

Subjects / Keywords:
Waste materials
Municipal solid waste
Industrial by-products
Geotechnical
Beneficial reuse
Dissertations, Academic -- Civil Engineering -- Masters -- USF
Genre:
bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

Notes

Abstract:
ABSTRACT: Marginal soils, including loose sands, soft clays, and organics are not adequate materials for construction projects. These marginal soils do not possess valuable physical properties for construction applications. The current methods for remediation of these weak soils such as stone columns, vibro-compaction, etc. are typically expensive. Waste materials such as scrap tires, ash, and wastewater sludge, offer a cheaper method for stabilizing marginal soils. As an added benefit, utilizing waste materials in soil stabilization applications keeps these materials from being dumped into landfills, thereby saving already depleting landfill space. Included in this report is an extensive investigation into the current state of research on waste and recycled materials in construction applications. Also included is an investigation on actual implementation of this research in construction projects. Upon completion of this investigation, an effort was made to determine waste materials specific to the state of Florida (waste roofing shingles, municipal solid waste ash, waste tires, and paper mill sludge) that could be used in stabilizing marginal soils through soil mixing techniques. Changes in the engineering properties of soils as a result of adding these waste materials were studied and recommendations on implementing these effects into construction applications are offered.
Thesis:
Thesis (M.A.)--University of South Florida, 2006.
Bibliography:
Includes bibliographical references.
System Details:
System requirements: World Wide Web browser and PDF reader.
System Details:
Mode of access: World Wide Web.
Statement of Responsibility:
by Delfin G. Carreon.
General Note:
Title from PDF of title page.
General Note:
Document formatted into pages; contains 55 pages.

Record Information

Source Institution:
University of South Florida Library
Holding Location:
University of South Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 001910368
oclc - 173366613
usfldc doi - E14-SFE0001700
usfldc handle - e14.1700
System ID:
SFS0026018:00001


This item is only available as the following downloads:


Full Text

PAGE 1

i Stabilization of Marginal Soils Using Recycled Materials by Delfin G. Carreon Jr. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Civil Engineering Department of Civil and Environmental Engineering College of Engineering University of South Florida Major Professor: Alaa K. Ashmawy, Ph.D. Manjriker Gunaratne, Ph.D. Abla Zayed, Ph.D. Date of Approval: July 11, 2006 Keywords: waste materials, municipal solid waste, industrial by-pr oducts, geotechnical, beneficial reuse Copyright 2006, Delfin G. Carreon Jr.

PAGE 2

i Dedication This work is dedicated to my parents. They’ve supported me mentally, physically, and most of all, financially in my efforts to achieve a master’s degree in geotechnical engineering at the University of South Florida.

PAGE 3

ii Acknowledgement There are several people to thank for their effo rts and help in this research. First and foremost would have to Dr. Ashmawy. Ev en though he wasn’t always around, I would not have been able to complete this wo rk without his guidance and direction. My colleagues at the University of South Fl orida including Brian Runkles, Nivedia Das, Aidee Cira, and the boss himself Mr. Maged Mi shriki offered their insight and time in helping with this project. And of course, my friends who were there for me when I needed them most.

PAGE 4

i Table of Contents List of Tables................................................................................................................. ....iii List of Figures................................................................................................................ ....iv Abstract....................................................................................................................... .......vi Chapter 1: Introduction......................................................................................................1 Introduction................................................................................................................... ..1 Scope of Project..............................................................................................................1 Organization of Thesis....................................................................................................2 Chapter 2: Literature Review.............................................................................................3 Introduction................................................................................................................... ..3 Breakdown of Materials..................................................................................................3 MSW Ash....................................................................................................................5 Scrap Roof Shingles....................................................................................................7 Paper Mill Sludge.......................................................................................................8 Scrap Tires..................................................................................................................9 Chapter Three: Materials.................................................................................................12 Introduction................................................................................................................... 12 Material Descriptions....................................................................................................12 MSW Ash..................................................................................................................12 Scrap Roof Shingles..................................................................................................15 Paper Mill Sludge.....................................................................................................18 Scrap Tires................................................................................................................20 Sand and Organic Clay.............................................................................................21 Chapter 4: Compaction Properties...................................................................................24 Introduction................................................................................................................... 24 Test Methods.................................................................................................................24 Results and Discussion.................................................................................................25 MSW Ash..................................................................................................................25 Scrap Roof Shingles..................................................................................................27 Paper Mill Sludge.....................................................................................................29 Scrap Tires................................................................................................................30

PAGE 5

ii Chapter 5: Shear Strength Properties...............................................................................32 Introduction................................................................................................................... 32 Unconfined Compression Test......................................................................................32 Direct Shear Test..........................................................................................................34 Chapter 6: Database Implementation...............................................................................38 Introduction................................................................................................................... 38 Overview of Database...................................................................................................38 Tables......................................................................................................................... ...39 Reuse Applications...................................................................................................40 Engineering Properties..............................................................................................41 Material Composition and L eachate Characteristics................................................42 Updating Database....................................................................................................46 Chapter 7: Conclusions and Recommendations..............................................................49 Conclusions...................................................................................................................4 9 General Recommendations.......................................................................................49 Materials Recommendations.....................................................................................50 Recommendations for Further Research...................................................................50 References..................................................................................................................... ....52

PAGE 6

iii List of Tables Table 2-1: Initial List of 24 Materials...........................................................................4 Table 3-1: Engineering Properties for MSW Ash.......................................................13 Table 3-2: Compaction and CBR Data for Scrap Roof Shingles................................16 Table 3-3: Engineering Prope rties for Paper Mill Sludge...........................................19 Table 3-4: Engineering Properties for Scrap Tires......................................................20

PAGE 7

iv List of Figures Figure 2-1: Materials Flowchart.....................................................................................5 Figure 2-2: Tire Buffings..............................................................................................10 Figure 3-1: a) MSW Ash as-Received b) After Sorting and Drying............................14 Figure 3-2: Grain Size Di stribution for MSW Ash.......................................................15 Figure 3-3: a) Scrap Roof Shingles as-Received b) Sc reened Shingles.......................17 Figure 3-4: Grain Size Distribu tion for Scrap Roof Shingles.......................................18 Figure 3-5: Plasticity Chart for Paper Mill Sludge.......................................................19 Figure 3-6: Grain Size Dist ribution for Florida Sand...................................................21 Figure 3-7: Direct Shea r Test on Florida Sand.............................................................22 Figure 3-8: Plasticity Index for Organics.....................................................................22 Figure 3-9: Plasticity Index for 10% MSW Ash and Organics....................................23 Figure 3-10: Plasticity Index for 30% MSW Ash and Organics....................................23 Figure 4-1: Compaction Curves for MSW Ash-sand Blends.......................................26 Figure 4-2: Compaction Curves for MSW Ash-organics Blends.................................27 Figure 4-3: Compaction Curves for Scrap Roof Shingle-sand Blends.........................27 Figure 4-4: Creep Test Apparatus.................................................................................28 Figure 4-5: Creep Test Results.....................................................................................29 Figure 4-6: Compaction Curves fo r Paper Mill Sludge-sand Blends...........................30 Figure 4-7: Crumb Rubber............................................................................................30 Figure 4-8: Compaction Curves for Crumb Rubber-sand Blends................................31 Figure 5-1: Typical Failure Mode for Organic Clay-MSW Ash Blends......................33 Figure 5-2: Stress-Strain Curves for MSW Ash-organic Blends..................................34 Figure 5-3: Shear Stress vs. Displacement for Sand.....................................................35 Figure 5-4: Shear Stress vs. Displa cement for Sand and 5% Shingles.........................35 Figure 5-5: Shear Stress vs. Displa cement for Sand and 10% Shingles.......................36

PAGE 8

v Figure 5-6: Effects of Shingl es on Friction Angle of Sand..........................................37 Figure 6-1: Recycled Materials Relational Database...................................................39 Figure 6-2: List of Proc esses within Database..............................................................40 Figure 6-3: List of Appli cations within Database.........................................................41 Figure 6-4: Engineering Properties for Scrap Tires......................................................42 Figure 6-5: Chemical Compounds Included within Database......................................43 Figure 6-6: Metals Included within Database...............................................................45 Figure 6-7: Organic Compounds within Database.......................................................45 Figure 6-8: Adding Case Studies Process.....................................................................46 Figure 6-9: Inputting Case Study for Yang et al., 2002................................................47

PAGE 9

vi Stabilization of Marginal Soils Using Recycled Materials Delfin G. Carreon Jr. ABSTRACT Marginal soils, including loose sands, soft clays, and organics are not adequate materials for construction projects. These ma rginal soils do not possess valuable physical properties for construction applications. Th e current methods for remediation of these weak soils such as stone columns, vibro-comp action, etc. are typically expensive. Waste materials such as scrap tires, ash, and wa stewater sludge, offer a cheaper method for stabilizing marginal soils. As an added benefit, utilizing waste materials in soil stabilization applications keeps these materi als from being dumped into landfills, thereby saving already depleting landfill space. In cluded in this report is an extensive investigation into the current state of re search on waste and recycled materials in construction applications. Also included is an investigation on actual implementation of this research in construction projects. Upon completion of this investigation, an effort was made to determine waste materials specific to the state of Florida (waste roofing shingles, municipal solid waste ash, waste tire s, and paper mill sludge) that could be used in stabilizing marginal soils through soil mixing techniques. Changes in the engineering properties of soils as a result of adding these waste materials were studied and recommendations on implementing these eff ects into construction applications are offered.

PAGE 10

1 Chapter 1: Introduction Introduction Recycled materials such as paper mill sludge and scrap roof shingles show potential for use in geotechnical engineeri ng applications. These materials can be processed to a more desirable product or us ed in their natural state as a suitable construction material. Part of the driving force for pushing recycled materials research is the fact that these material s possess equivalent or even better engineering properties typical for the conventional construction material s. The other part would be the fact that reusing these materials ultimately keeps them out of landfills. This is paramount due to the fact that landfill sp ace is constantly and rapidly depleting. Scope of Project There are three major tasks associated w ith the current research. The first task was a comprehensive literature review and in formation collection on recycled materials. In the past, much effort has been made to fi nd new applications for recycled materials. Depleting landfill space is the major motivation for such research. Finding new uses for materials that typically end up in landfills is mandatory in order to keep from using land for landfills. This first task was time-consum ing mostly because of the vast amounts of information available from so many different sources. As a re sult of this literature review and information collection, specific materials were chosen to be part of the next task, the experimental program. The experimental program included tes ting materials chosen for the current research. Tests were conducted to determin e index properties, compaction properties, and strength properties of the materials. Th e materials were then blended with either

PAGE 11

2 sand or clay and tested further in order to determine how these materials affected the properties of the sand and clay. The third task included updating of the recycled materials relational database. Past research on recycled materials led to the creation of a database including all important information when considering th e use of recycle materials in various applications. The database was populated with information collected from the literature review as well as results from the experimental program of the current research. Organization of Thesis Chapter 2 will contain introduce the list of materials considered in this study. A breakdown of the materials is included as well a literature revi ew on the materials selected for the testing program of this study. Chapter 3 includes a detailed description and characterization of the ma terials tested including inde x properties and environmental issues. Chapters 4 and 5 discuss the compac tion behavior and shear strength properties of the materials, respectively. Chapter 6 includes a brief discussion of the recycled materials database that was updated as a re sult of the literature review. Chapter 7 includes conclusions and recommendati ons as a result of this study.

PAGE 12

3 Chapter 2: Literature Review Introduction The idea of using recycled materials in construction applications is not a new concept. Reports on this subject can be found dating back to the 1970’s. The Organization for Economic Co-operation and De velopment (OECD) published a report in 1977 entitled, “Use of Waste Materials and By -products in Road Construction.” The OECD was a conglomeration of countries in cluding the United States that was put together in 1960. Their report contained in formation on domestic and industrial wastes and how each could be utili zed in roadway construction. Using recycled materials in construc tion makes sense because they offer two major advantages over traditiona l construction materials. Firs t, they are typically less costly due to the fact that they are a waste pr oduct that already needs to be disposed of. Second, finding alternative uses for these mate rials keeps them out of landfills, ultimately saving already depleting landfill space. These two points alone make the case for finding alternative reuse applications for recycled materials. Breakdown of Materials At the beginning of literature for the curre nt research, an initial list of 24 waste and recycled materials was compiled. These 24 initial materials were chosen for their potential to serve as a construction material in civil engineering applications, with a focus on the geotechnical side. In other words, thes e materials were chosen for their potential to serve as either fill material, base or subba se material for roadway construction, or as a soil amendment for stabilizing weak soils. Another reason for these materials to be

PAGE 13

4 chosen was that each one on the initial list of 24 were reported to have been either studied for alternative reuse applications, actually implem ented in a reuse application or both. This list included materials ranging from municipal wastes such as paper, glass, and plastics to industrial wast es like slag and coal com bustion by-products. A complete list of these materials is shown in Table 2-1. Table 2-1: Initial List of 24 Materials Paper Demolition Debris Paper Mill Sludge Plastics Blast-Furnace Slag Wood Waste Incinerator Ash (MSW) Steel Mill Slag Carpet Fibers Scrap Tires Non-Ferr ous Slag Mine Tailings Roof Shingles Cement/Lime Kiln Dust Phosphogypsum Fly Ash (Coal Ash) Reclaimed Asphalt Pavement Quarry Waste Bottom Ash (Coal) Reclaimed Concrete Pavement Glass Scrubber Base (Coal) Foundry Wastes Boiler Slag During the literature review it was dete rmined that only certain materials would be taken into consideration during the testi ng program. Certain crite ria were set for each material to meet in order to decide whethe r or not the material would be tested. Two major aspects of each material were evaluated: availability in Florida and environmental issues. The availability of the material is important because if sufficient amounts are not being produced, then it would not be a wi se choice of construction material. Environmental issues were a major criterion because some of the materials such as phosphogypsum are associated with radon emissions and would not be considered in the testing program. A flowchar t was developed, shown in Figur e 2-1 and each material was subjected to it. Once each material was subjected to the flow chart, 4 materials were selected to be considered in the testing program. These materials showed that ample amounts were produced and that they were more or less safe enough to be considered for reuse in geotechnical applications. The materials sele cted for the current research included: municipal (MSW) solid waste incinerator ash, scrap roof shingles, paper mill sludge, and scrap tires. The rest of this chapter will di scuss the past research conducted specific to these 4 materials.

PAGE 14

5 If yes, have TCLP/SPLP and totals tests been performed on the material? If no, then these tests need to be performed If yes, are the results below the EPA mandated maximums, as well as the Florida Soil Cleanup Target Levels? If no, the material is no good unless intensive study showing that material is good can be provided and approved by FDEP If yes, then the material is suitable for beneficial reuse Have geotechnical tests shown the material actually improves the soil? If yes, the material is suitable for beneficial reuse provided that quality assurance measures can be proved to have been taken to assure consistencies If not, these testes need to be performed. Once quality reassurance is provided, contact FDOT for actual field testing. These sites will need to be monitored for leaching and settlement by the material supplier. Are significant amounts of the material available? If no, this material is not suitable for beneficial reuse. Figure 2-1: Materials Flowchart MSW Ash A fair amount of research has been conducted on the prope rties and potential reuse application of MSW ash. A 2004 st udy by Muhunthan et al. investigated the geotechnical properties of MSW ash mixes. Th e mixes in this study included blends of bottom ash and fly ash produced at a mass burn facility in Spokane, Washington. The blends tested were composed of 0, 20, 40, 60, 80, and 100% bottom ash to fly ash and visa versa totaling 6 different blends. Samples were tested for compaction behavior, shear strength by the direct sh ear test, and permeability. From the compaction tests, it was seen that the incinerator ash mixes exhibit behavior similar to that of clays. It s hould also be noted that incinerator ash mixes achieved much lower unit weights than typi cal values for sand and clay (Muhunthan et

PAGE 15

6 al., 2004). When comparing botto m ash to fly ash it was seen that the 100% bottom ash sample exhibited significantly lower optimum moisture content than the 100% fly ash sample. This was explained by the fact th at fly ash contained much more smaller particles than bottom ash thereby increasing th e amount of surface area of particles to be covered with moisture. (Muhunthan et al., 2004). Direct shear tests were conducte d on each blend at optim um moisture content and on the as-received samples of incinerator ash. Results showed that the friction angle for the blends increased with percentage of bottom ash with the highest value being 50.70 for the 100% bottom ash blend. The opposite wa s true for calculated cohesion values. The cohesion of the blends decreased with increasing percentage of fly ash with the highest value being 34.1 kPa for the 100% fly ash blend. The overall results from the direct shear testing showed that incinerator ash blends will tend to have better strength characteristics than typical fill materials and since ash is relatively lighter than typical fill material, lowe r normal stresses. This in turn will allow for the generation of lower normal stresses on foundation soils (Muhunt han et al., 2004). Similar to the direct shear tests, permeability was investigated on a ll blends at optimum moisture content as well as at as-received mo isture content. Results indicated that 100% bottom ash gave a permeability coefficient of 1.4 x 10-3 cm/sec at optimum moisture content. This study did not include any data on the chemical composition of the MSW ash tested or how applying this material in construction applications would affect the surrounding environment. A similar study on the use of MSW ash as a highway fill material was conducted in 1995 by Consentino et al. The major diffe rence when compared to Muhunthan et al, 2004 is that this study included an in depth i nvestigation into the environmental impacts of reusing MSW ash. In this study an act ual embankment made from combined bottom and fly MSW ash was designed and constr ucted. The field performance of the embankment was evaluated as well as its environmental characteristics. A leachate collection system was installed during cons truction of the embankment. Rainwater runoff was also collected. The leachate a nd runoff collected was analyzed for heavy metal concentrations and toxicity limits.

PAGE 16

7 The results of this study indicated that toxicity limits were not exceeded in the runoff or the leachate after 6 months. Dri nking water standards were also taken into consideration. These standards were slight ly exceeded in the leachate which showed a selenium concentration of 0.13 mg/l. Th e drinking water standard for selenium concentration is 0.1 mg/l. Overall the results from this st udy and the study by Muhunthan et al, 2004 indicate that MSW incinerator ash would make a proficient construction material when blends of bottom ash and fly ash are used. It is now pertinent to investigate how adding MSW ash would affect the engineering propert ies of sand or clay as in the current research. Scrap Roof Shingles There has not been as much research on the beneficial reuse of scrap roof shingles when compared to other widely researched r ecycled materials such as scrap tires or MSW ash. Reported reuses of scrap r oof shingles include using the material as an additive to hot mix asphalt and as a gravel substitute for the wearing surface of rural roads. In a 2004 study by Hooper and Marr, the eff ects of adding asphalt shingle tabs to different soils including crus hed stone gravel, a silty sa nd, a clean sand, and clay was investigated. When mixing the shingle material with crushed stone gr avel 5 different mix percentages were tested. Varying amounts of shingle tabs of 25.4 mm minus (0, 33, 50, 67, and 100% by volume) were added to the gr avel. For the clean sand, silty sand, and clay a fixed amount of 33% by volume shingle tabs were blended in. A number of different tests were c onducted on these samples, including sieve analysis, Atterberg limits, compaction, and Calif ornia bearing ratio (CBR). Test results from this study varied with shingle to soil mix percentages. Adding the shingle tabs to crushed stone gravel, silty sand, and clean sa nd resulted in a decreasing affect on the strength according to the CBR test. The only strength increase was experienced when the shingles were added to clay. This can be e xplained by the ability of the clay to hold the shingle tabs in place by cohesi on. This would allow for the shingles to remain in place

PAGE 17

8 during loading and refrain from slipping. Th is in turn would for the distribution of pressures throughout the sample as the load is applied (Hooper and Marr, 2004). The study by Hooper and Marr, 2004 does give an idea on how addition of scrap shingle tabs can affect the stre ngth of different types of so ils however; the shingles used in this study were obtained from a pre-consum er source. They were basically the scraps leftover from shingle production. This source of waste shingles will typically end up in a landfill and is in need of some sort of recycling application but only makes up 10% of the total shingle waste produced nationally. The majority of shingle waste produced comes from tear-off post consumer shingles. For the current research, post-consumer tear-off shingles will be evaluated when mixed with soils. The other issue related to scrap shingle reuse not mentioned in this study is the potenti al for the material to contain asbestos. This is an issue that needs to be addresse d when one is considering reusing scrap roof shingles. Paper Mill Sludge Paper mill sludge is a by-product of the paper manufacturing industry. There have been several studies on reuse applica tions for paper mill sludge. A study completed by Moo-Young and Zimmie 1996 was conducted in order to determine the geotechnical properties of paper mill sludges specifically for use in landfill covers. They collected and studied 7 different paper mill sludges from different sources including wastewater treatment plants, paper mills, and a sludge monofill. The sludges were tested for geotechnical properties such as Atterberg lim its, compaction behavior, shear strength and permeability. All of the sludges studied exhibited high water content, high compressibility, and low solid content. The fact that the sludge can be compacted to low permeability makes this material ideal for use as hydraulic barrier for landfills (Moo-Young and Zimmie, 1996). Problems occurred during testing sin ce the sludge has a tendency to form coarse flocs upon drying, which are difficult to pulveri ze. All the sludge samples collected exhibited high Atterberg limits. There was a wide range of optimum moisture contents from 50 to 100%. Shear strength testing was completed using consolidated undrained

PAGE 18

9 triaxial compression tests with pore pressure measurements. Friction angles ranged from 250 to 400 while the cohesion was between 2.8 and 9 kPa. Results from this study indicate that paper mill sludge would make a suitable landfill cover material. Another study conducted by Simpson et al 2004 looked at the overall history and technology associated with the beneficial reus e of paper mill sludge. Overall, the major reuse application for paper mill sludge has been using the material for landfill cover. According to this study paper mill sludge, term ed fiber-clay when talking about reuse, has been combined with pozzola nic material (fly ash) and us ed as both subbase material and as a finished surface for sec ondary and remote access roads. Simpson et al also describes the thixotropic properties of paper mill sludge. In other words, when the sludge is dried to around the optimum moistu re content (typically around 60%) the material resembles paper mach e. Addition of moisture however, does not return the material to its original consis tency, but rather to a mixture of lumps of paper mache in water (Simpson et al., 2004). Other reported reuses for paper mill sludge according to this study include kitty litter, worm bedding, commercial absorbents, and agricultural animal bedding. Neither of th e two studies mentioned on paper mill sludge addressed the environmental hazards associated with reusing paper mill sludge, such as potential for leaching of heavy metals. Scrap Tires Similar to MSW ash, scrap tires have b een studied extensivel y with regards to alternative forms of disposal and recycling. Tires have been reused in many different applications mainly related to production of new rubber based materials. Another major form of tire recycling is burning tires for fuel at tire derived fuel (TDF) facilities. There have also been reports that de scribe construction related appl ications for waste tires such as crumb rubber modifiers for highway pavement and shredded tires as fill material. The reuse application for tires is dependent on how the tires are processed. Processing basically includes shredding, removing of me tal reinforcing, and further shredding until the desired material is achieved.

PAGE 19

10 In a report by Edinciler et al, 2004 th e researches looked at the effects on the shear strength of sand when tire buffings ar e added. Tire buffings, shown in Figure 2-2, are the by-product of th e tire retread process. The tir e buffings in this study were between 1 and 4 mm in diamet er and 2 to 40 mm in length. The small diameter and fiber shape of the buffings make them ideal form mixi ng with soil compared to tire shreds or chips (Edinciler et al., 2004). Figure 2-2: Tire Buffings Large scale direct shear te sts were conducted on the buffings themselves and on a sand-tire buffing blend. Results show that at low a vertical stress of 20 kPa, the addition of tire buffings stiffened the sand at low deforma tions. At higher ver tical stresses the (40 kPa) the addition of tire buffings lowers the ultimate strength of sand, however the displacement at failure shifts from 12 mm for sand only to 35 mm when buffings are added. From these results, it can be deduced that adding tire buffings to an embankment material can allow for the embankment to undergo larger strains without failure. A report by Consentino et al., 1995 investig ated the basic engi neering properties and environmental impacts of using wast e tire chips in highway construction applications. The report suggest ed utilizing scrap tire chips as a lightweight fill material. Scrap tire chips would make an ideal lightwe ight fill because they’re readily available,

PAGE 20

11 relatively inexpensive (by-pr oduct), and are easily handled by standard construction equipment. A couple of downfalls associated with using scrap tire chips as lightweight fill include the fact that design parameters ar e based on field trials and the restricted use below the groundwater table (Consentino et al, 1995). The report by Consentino et al, 1995 also included information on the environmental impacts of using scrap tire chips as fill material. TCLP testing and extraction procedure (EP) toxi city tests were conducted on scrap tire chip samples. TCLP results indicated that the leachate from the samples were one to three times less than TCLP regulatory levels. The EP toxici ty test showed that the amount of heavy metals extracted from the samples were well below EPA toxicity levels. Another major risk associated with reusing scrap tires discussed in the report by Consentino et al, 1995 was the potential for spontaneous combustion. Reports of fires occurring at tire stock piles have been noted and investigated. St udies have shown that the primary reason for combustion occurring is heat accumulation by exothermic reactions due to oxidation of exposed steel in the tires. This can be avoi ded when using scrap tires as fill material by removing the steel during the shredding process (Consentino et al., 1995).

PAGE 21

12 Chapter Three: Materials Introduction For the current research, four materials were considered for beneficial reuse in soil stabilization applications. These materi als included: municipal solid waste (MSW) incinerator ash, scrap roofing shingles, crum b rubber tires, and paper mill sludge. These materials were selected based on their engineer ing properties, availabi lity in Florida, and their potential for use in ge otechnical applications. For the current research the main applic ation of these materials focused on soil blending. In other words, these materials were mixed with soils and tested in order to determine whether or not the addition of the material enhanced the engineering properties of the soil itself. Each material was mixed w ith either sand or organi c material and tested for index properties, compaction behavior, and strength effects. Th is chapter contains information pertaining to the origin, descripti on, and index properties of each material, as well as some current reuse applications. Al so included in this chapter is information related to the environmental impacts of applying these materials in soil blending applications. Material Descriptions MSW Ash MSW ash is a by-product that is produced as a result of burning municipal solid waste. There are two differe nt types of facilities that produce MSW ash, mass burn and refuse derived fuel (RDF). Mass burn faciliti es basically incinerate all the waste entering in the waste stream. RDF facilities process the incoming waste by removing the

PAGE 22

13 inorganic content such as glass, ceramics, and metals prior to incineration. Although RDF facilities make an effort to separate the waste before it is incinerated there is still a large variability in the compos ition of the resulting ash. This has led to some hesitation in considering MSW ash for use in constructio n applications. MSW ash has been used in asphalt concrete applications and in asphalt paving mixes, how ever the material has been termed “borderline” hazardous by the EPA due to its potential for leaching of hazardous materials. Previous research on MSW ash in reuse applications has resulted in reported engineering properties summ arized in Table 3-1. Table 3-1: Engineerin g Properties for MSW Ash Unit Weight (kg/m3) 965 1290 Specific Gravit y 1.86 2.24 CBR Value 95 190 Friction A n g le 40o 45oAbsorption ( % ) 3.6 14.8 Max Dry Density (kg/m3) 1730 The MSW ash used in this study was obt ained from the Pinellas County solid waste facility. According to the information provided by the County, the ash samples obtained were a combination of bottom and fl y ash. This combined ash was stabilized using the WES-PHix process and was processe d to a minus five inch size by removing the ferrous and non-ferrous metals to be r ecycled. Typically th e ash generated from municipal solid waste incine ration is land filled. Upon first inspection of th e as-received MSW ash sample s, it was seen that the particle size ranged from larg e bulky materials (glass, ceramics, etc.) to fines. The appearance of the ash was mostly dark to light gray with the finer particles being lighter in color. Grain size distribution of the MS W ash was determined by sieve analysis in

PAGE 23

14 order to classify the material. Prior to r unning the sieve analysis, all of the large, bulky material was removed from the sample. A porti on of the as-received sample is shown in Figure 3-1(a). This was done until the ash was allowed to pass a #4 sieve (4.75 mm). The sample was then dried and placed in the sieve shaker. A small portion of the sorted and dried ash used in the siev e analysis is shown if Figure 3-1(b). From the grain size distribution curve shown in Figure 3-2, it can be seen that the material classified as a poorly graded sand. (a) (b) Figure 3-1: a) MSW Ash as Recei ved b) After Sorting and Drying

PAGE 24

15 0 10 20 30 40 50 60 70 80 90 100 110 0.010.1110Particle size (mm)Percent finer Figure 3-2: Grain Size Distribution for MSW Ash Scrap Roof Shingles Roof shingle scrap maybe derived from tw o different sources, the first being the leftover material from roof shingle production. These are termed roof shingle tabs. The second, and more predominant source in term s of amount produced comes from shingle replacement and demolition projects. These are termed tear-off roof shingles. The major difference between shingle tabs and tear-off shingles is the variability of the final product. Shingle tabs, when collected, are uniform in thei r engineering and environmental properties. Tear-off shingles, on the other hand, are much more variable. This is mostly due to the fact that when te ar-off shingles are collected, they will typically contain other materials such as nails, w ood, and metals, mixed in with the shingle material. Typically roofing shingles are made up of three major constituents: asphalt, fiberglass, and aggregate. As mentioned in th e Literature Review, some states have used

PAGE 25

16 roofing shingle waste in limited recycling app lications such as hot mix asphalt, however a large portion of shingles produced still ends up in the landfills (Hooper, 2004). The main environmental concern with reusing this mate rial is the potential for the shingles to contain asbestos. In a stu dy conducted by Hooper and Marr (2004) on moisture-density relationships and CBR values of scrap roof shingles, they looked minus 25.4 mm ground and screened shingle material. Their results are shown in Table 3-2. It should be noted that the shingle material used in the 2004 study were pre-cons umer shingle tabs provided by the manufacturer. Table 3-2: Compaction and CBR Da ta for Scrap Roof Shingles Optimum Moisture ( % ) 7 Max Dry Density (kN/m3) 15.7 CBR % 6 Swell % 0.5 The samples used in the current resear ch were obtained from a roof shingle recycling plant in Hillsborough County. Sim ilar to the MSW ash obtained, the particle sizes ranged from large bulky pieces to crus hed fines. The samples also contained a number of foreign materials su ch as nails and pieces of w ood. The as received shingles were mostly dry and dark gray to black in color and are shown in Figure 3-3(a). Similar to the MSW ash, the larger pieces of shingl e were removed the material passing through a #4 sieve was subjected to sieve analysis. Fr om the grain size distribution curve shown in Figure 3-4 it can be seen that the scrap roof shingles resemble a well graded sand.

PAGE 26

17 (a) (b) Figure 3-3: a) Scrap Ro of Shingles as-Received b) Screened Shingles

PAGE 27

18 0 20 40 60 80 100 0.010.1110100 Particle size (mm)Percent finer Figure 3-4: Grain Si ze Distribution for Scrap Roof Shingles Paper Mill Sludge Waste paper mill sludge, also termed fiber-clay when talking about reuse and recycling applications is a major by-product of the pa per manufacturing industry. There is a high residual of clay content in paper mill sludge due to the amount of kaolin clay in the manufacturing of paper products. Reported reuse applications for fiber-clay include landfill cover material, soil amendment for agricultural purposes, and as road bed material for remote access road s (Simpson and Zimmie, 2004). Typically, paper mill sludge exhibits high water content and a low solid content. However, the material may be compacted to a low permeability, a desired property for landfill cover material. The environmental issu es that arise with the paper mill sludge in geotechnical applications include the potential to leach hazardous materials. Similar to MSW ash, paper mill sludge is a highly variable material in terms of its chemical makeup. The engineering properties for this material shown in Table 3-3 represent values taken from the few studies previously conducted for paper mill sludge.

PAGE 28

19 Table 3-3: Engineering Prope rties for Paper Mill Sludge Specific Gravit y 1.88 1.96 Plastic Index191 Compression Inde x 1.24 Permeability ( cm/s ) < 10-8 The paper mill sludge used in this research was obtained from a paper mill manufacturing facility in Nort heast Florida. The sludge was dark gray to black in color and exhibited a high water content. The phys ical appearance of the sludge closely resembled an organic clay. Atterberg limits were evaluate d on the as-received sludge in order to classify the material. The liquid limit (LL) was determined using the fall cone test according to British Standards BS 1377. Fr om the plasticity chart in Figure 3-5, it can be seen that the paper mill sludge behave s like a kaolin clay. The plasticity index (PI) for the material is right around 115 and pl ots directly on the “A” line on the plasticity chart. 0 50 100 150 200 250 300 350 400 450 500 0100200300400500600Liquid Limit (LL)Plasticity Index (PI) "A" Line "U" Line Plasticity Index Figure 3-5: Plasticity Ch art for Paper Mill Sludge

PAGE 29

20 Scrap Tires The last material considered in this re search was waste scrap tires. Scrap tires come from any type of old truck or automob ile. Scrap tires are typically land filled or incinerated for fuel. As mentioned in the lite rature review, scrap tire s are one of the most extensively researched recycled materials. This extensive research has led to the generation of ASTM standards for reusing scra p tires in different a pplications including the ASTM designation D6270-98 “Standard Prac tice for Use of Scrap Tires in Civil Engineering Applications. Recycling applications include fill material and hot asphalt concrete (Consentino et al., 1995). The major ity of reuse applica tions for scrap tires require processing of the material prior to reuse. Processing of tires basically consists of shredding the tires, removing the steel, and fu rther shredding until the desired product is produced. The tires used in the current resear ch were obtained from a rubber tile manufacturing company in Hillsborough County. This company utilized scrap tires and processed them to a crumb rubber material comp rised of very fine material. The samples obtained were relatively dry, completely uniform, free of any non-rubber material, and black in color. Reported engineering propert ies for scrap tires are given in Table 3-4. Table 3-4: Engineering Properties for Scrap Tires Unit Weight (kg/m3) 390 584 Specific Gravit y 1.1 1.3 Absorption ( % ) 2 3.8 Friction A n g le* 19o 41oPermeability ( cm/sec ) 1.5 15 Young's Modulus ( kPa ) 770 1250 *Depending on how tires are processed i.e. shreds, crumb, etc.

PAGE 30

21 Sand and Organic Clay For the testing program of this project, described in detail in chapters 4 and 5 of this report, the materials described above were blended with either sand or organic material depending on the desired application. It is pertinent to desc ribe these materials in this portion of the report. The sand was obtained from a job site on the campus of the University of South Florida provided by the physical plant. The sa nd was fairly uniform with small pieces of lime rock existing throughout the samples. Sieve analyses conduc ted on the sand, shown in Figure 3-6 show that the sand may be classi fied as an A-3 material according to the AASHTO classification system. 0 20 40 60 80 100 0.010.1110100 Particle size (mm)Percent finer Figure 3-6: Grai n Size Distribution for Florida Sand The friction angle of the sand was determin ed by the direct shear test. This test was also conducted on sand samples blended with scrap roof shingles and is described in more detail in chapter 5. The results of the direct shear test in Fi gure 3-7 show the sand having a friction angle of 300.

PAGE 31

22 Figure 3-7: Direct Shear Test on Sand The organic material was obt ained from a dredging proj ect site in Pinellas County provided by the city of St. Petersburg. Atte rberg limits for the organic material were tested and the PI came out to a value of 94. The plasticity char t shown in Figure 3-8 shows that the material can be cl assified as an organic clay. 0 50 100 150 200 250 300 350 400 450 500 0100200300400500600Liquid Limit (LL)Plasticity Index (PI ) "A" Line "U" Line Plasticity Index Figure 3-8: Plasticity Index for Organics 0 1 2 3 4 5 6 7 8 9 02468101214Normal Stress (psi)Shear Stress (psi)

PAGE 32

23 The effects of adding MSW ash to the plas ticity of organic clay was investigated. Two mix ratios, 10% and 30% MSW ash by wei ght to organic clay were tested. The results are shown in Figures 3-9 and 3-10, re spectively. The addition of MSW ash to the organic clay had a significan t effect on the plastic index. Adding 10% MSW ash to the organics caused the plastic index to drop from 94 to 13. When 30% MSW ash was added, the plastic index dropped a little more to 10.7. From these results it can be said that the cementing effects of the MSW ash can change a very high plasticity clay to a medium plasticity clay. 0 20 40 60 80 100 120 140 160 180 200 050100150200250Liquid Limit (LL)Plasticity Index (PI ) "A" Line "U" Line Plasticity Index ```` Figure 3-9 Plasticity Index for 10% MSW Ash and Organics 0 20 40 60 80 100 120 140 160 180 200 050100150200250Liquid Limit (LL)Plasticity Index (PI ) "A" Line "U" Line Plasticity Index Figure 3-10: Plasticity Index for 30% MSW Ash and Organics

PAGE 33

24 Chapter 4: Compaction Properties Introduction The principle behind compaction of a soil is basically using mechanical energy to increase the density of the mate rial. When loose soils are compacted, there is an increase in the unit weight of the soil, which in turn leads to higher strength. It is also important to take into account the affect of the wa ter content of the soil during compaction. Addition of moisture to soil will allow for the soil particles to slip over themselves and cause further densification than if the soil wa s completely dry. Adding more moisture to the soil will increase the stre ngth to a point. After this point, any further addition of moisture will not lead to any more incr ease in strength. This point is called the optimum moisture content. The maximum dry density of the soil will occur at the optimum moisture content. The major reuse applications for the mate rials considered in the current research are in the construction field. Therefore it is important to know how the addition of the recycled materials to soils will affect th e compaction behavior. All the materials considered were mixed with the sand descri bed in chapter 3 and subjected to compaction testing, in order to determine how they a ffect the optimum water content and maximum dry density. Test Methods The methods of compaction testing for al l sand-recycled material samples were the same. Testing was done in accordance with the ASTM Standards under the designation: D 698-91 “Test Method for Labor atory Compaction Characteristics of Soil Using Standard Effort.” In this method a 4in diameter mold that is 4.6-in in height

PAGE 34

25 without the extension was used along with a 5.5-lbf hammer dropped from a 12-in height. The mold was filled with 3 layers of soil each compacted using 25 blows from the hammer. After compaction, the extension wa s removed and the excess soil was trimmed from the top. The mold was weight in or der to determine the unit weight since the volume of the mold is fixed at 1/30 ft3. For determination of water content, the samples were dried in a bulk oven for at least 24 hours. A minimum of 6 trials were run for each sample in order to obtain the moisture content-dry unit weight curve. Compaction curves for all tests run we re plotted along with the zero air voids (ZAV) curve. The ZAV curve represents the theoretical maximum dry unit weight for a given moisture content. This maximum dr y unit weight occurs when there is no air present in the void spaces. Test results and observations for the compaction behavior using each material are discu ssed in this chapter. Results and Discussion MSW Ash MSW ash was mixed with sand and or ganic clay separately in varying percentages. Samples of 0, 1, 5, and 10% MSW ash by weight blended with were tested. In preparing the samples, the MSW ash was fi rst screened and dried. The ash was then passed through a #4 sieve (4.75 mm). This fraction was then blended with sand by hand in the varying percentages mentioned above. The samples were blended until it visually appeared that the ash was uniformly spread throughout the sand. Th e ash-organic blends tested included 0, 10, and 30% ash by weight to organics. These samples were prepared similar to the sand samples. The compaction curves for ash-sand blends are plotted in Figure 4-1. From the compaction curves it can be seen that the addition of MSW ash has an increasing effect on the maximum dry density of the sand. The sand alone (0% MSW Ash) shows a maximum dry density of 106.5 lb/ft3. The addition of each percentage of ash led to an increase in maximum dry density. The la rgest increase occurred when 10% MSW ash by

PAGE 35

26 weight was added to the sand. This resulted in an increase of maximum dry density to 110 lb/ft3. This increase in maximum dry density can be attributed to the pozzolanic nature of the ash material. In other words, the ash will react with the added moisture and cause a cementing effect, which in turn leads to increased strength of th e soil. This effect should increase with increasing percentage of MSW ash content. Figure 4-1: Compaction Curv es for MSW Ash-sand Blends The compaction curves for the ash-organic ble nds are shown in Figure 4-2. The curves show similar results to the ash-sand blends, although the effect is not as pronounced. The addition of MSW ash does show a slight increas e in the dry unit weight of the organics and a decrease in the opt imum moisture content. 98 100 102 104 106 108 110 112 114 0510152025 Moisture ContentDry Unit Weight (lb/ft3) 0% MSW Ash 1% MSW Ash 5% MSW Ash 10% MSW Ash ZAV LineZAV Line

PAGE 36

27 Figure 4-2: Compaction Curves for MSW Ash-organic Blends Scrap Roof Shingles The scrap roof shingle samples were mixed with sand in 0, 1, 5, and 10% by weight. The preparation of the samples was similar to the MSW ash. The results of the compaction tests are shown in Figure 4-3. From the plotted curves it can be seen that the addition of scrap roof shingles does not effec tively result in any si gnificant increases in the maximum dry unit weight of the sand. A ddition of 1% and 5% shingles to sand had little to no effect on the maximum dry densit y. 10% addition caused an increase of 1 lb/ft3 in maximum dry density. From these re sults it can be shown that scrap roof shingles do not perform well in so il stabilization through blending. Figure 4-3: Compaction Curves for Scrap Roof Shingle-sand Blends 100 102 104 106 108 110 112 0510152025 Moisture Content (%)Dry Unit Weight (lb/ft3) 0% Shingles 1% Shingles 5% Shingles 10% Shingles ZAV Line 45 50 55 60 65 70 75 80 20304050607080 Moisture content (%)Dry unit weight (lb/ft3) 0% MSW ash 10% MSW ash 30% MSW ash Zero air voids

PAGE 37

28 In addition to the effect on compaction be havior, the creep behavior of scrap roof shingles was also investigated. The creep test shows how the shingles would deform over time under a constant load. This behavi or is important when considering a material to be used in roadway co nstruction applications. For this test two samples were analyz ed: 100% dry sand and 100% dry scrap roof shingles. Each sample was compacted in a st andard Proctor mold in three layers. Each layer was compacted with 25 blows from a standard Proctor hammer (5.5-lbf). The compacted samples were placed in a rack and a load hanger was placed on top of the sample. The apparatus of the te st is shown in Figure 4-4. Figure 4-4: Creep Test Apparatus Once the sample was compacted and pl aced under the load hangar the load was applied by adding weights to the bottom of th e hangar. Two tests were conducted under different constant loads for each sample. Loads of 45 and 125 lbs were applied. Deformation was measured using a dial gauge placed on top of the load hangar. Results of the Creep tests were plotted and shown in Figure 4-5. The plot shows that, over time scrap shingles tend to deform much more than the sand. Dial Gauge Load Hangar Mold

PAGE 38

29 0 0.02 0.04 0.06 0.08 0.1 0.12 110100100010000 Time (min)Displacement (in) Sand, P = 45 lbs Sand, P = 125 lbs Shingles, P = 45 lbs Shingles, P = 125 lbs Figure 4-5: Creep Test Results Paper Mill Sludge The paper mill sludge required more prepar ation than the ash and shingles before it could be blended with sand. The as-receiv ed sludge was high in water content. The sample to be blended was first dried in an oven with the temperature not exceeding 600 C. The temperature was kept at this level in so th at any organic material would not burn off. Once the sludge was dried out it formed into co arse clumps of varying sizes. The larger clumps were fairly easy to break apart but the smaller ones were much more dense and harder to break up. These smaller clumps needed to be pulverized using a particle crusher before they could pass the #4 sieve. Once the sludge samples were screen ed they were blended with sand and subjected to compaction testing. The comp action curves are shown in Figure 4-6. Blends of 1% and 5% by weight paper mill sl udge to sand were tested. From Figure 4-6 it can be seen that the addition of paper mill sludge led to a decrease in the maximum dry density of the sand. The d ecrease was more pronounced when 5% sludge was added compared to 1% sludge. For this reason a 10% paper mill sludge to sand blend was not tested.

PAGE 39

30 Figure 4-6: Compaction Curves for Paper Mill Sludge-sand Blends Scrap Tires The scrap tire samples received from th e rubber tile manufacturer were in the form of crumb rubber. The crumb rubber was fairly dry and uniform as shown in Figure 4-7. The material did not require any pr eparation prior to blending with sand. Compaction testing was applied to 0, 1, and 5% crumb rubber tires by weight and sand blends. Compaction curves are presented in Figure 4-8. The addition of crumb rubber to sand had a similar decreasing effect on the maximum dry density of sand. For this reas on a 10% crumb rubber to sand blend was not tested. Figure 4-7: Crumb Rubber 90 95 100 105 110 115 120 0510152025Moisture ContentDry Unit Weight (lb/ft3) Z.A.V. 1% Paper Mill Sludge 5% Paper Mill Sludge 0% Paper Mill Sludge

PAGE 40

31 Figure 4-8: Compaction Curves for Crumb Rubber-sand Blends 90 95 100 105 110 115 120 0510152025Moisture ContentDry Unit Weight (lb/ft3) Z.A.C. 1% Waste Tires 5% WaSte Tires 0% Waste Tires

PAGE 41

32 Chapter 5: Shear Strength Properties Introduction The materials considered for the current research were subjected to a strength testing program when blended with soils. The materials tested such as MSW ash did improve the compaction characteristics of sa nd, however it is importa nt to observe how this material can improve the shear strength of a weak soil that may be encountered in the field such as organic clay. In order to dete rmine the effects of this material on the shear strength of organic clay, MSW ash was blende d in and the samples were subjected to the unconfined compression test. The other material that was tested for st rength properties was scrap roof shingles. From the compaction testing, it was seen that adding scrap shingles to sand did have cause a slight improvement when blended with sand. In order to determine the strength characteristics of this material, the shingles were blended with sand and subjected to the direct shear test. This chap ter describes the tests conducted and a discussion of the test results. Unconfined Compression Test The unconfined compression test was run on organic clay blended with MSW ash. The test was run in a triaxial cell mounted on a Loadtrac II load frame system. The samples tested included a 10% by weight MS W ash to organics and a 30% by weight ash to organics. The samples were mixed and unde r-compacted inside a cylindrical mold at their respective optimum moisture contents. The under-c ompaction technique involved increasing the number of blows with each lift The optimum moisture contents were evaluated during the compacti on testing. Blending of th e materials was done by hand

PAGE 42

33 while both the ash and organics were dry and un til the sample looked uniform to the eye. Water was added in small amounts and the sample was mixed until the desired moisture content was achieved. A split mold for preparing triaxial samples was used. The samples were compacted in the mold in 5 lifts using a tamper until the maximum dry unit weight was achieved. Once each sample was compacted, the mold was removed and the sample was placed in the triaxial chamber. The chamber was placed in the load frame and a strain rate of 2%/min was applied until the sample reached failure. Each sample tested showed typical failure mode of a clayey sand rather than clay. The samples tended to shear diagonally rather then swell as shown in Figure 5-1. The results of the unconfined compression tests are shown in Figure 5-2. The results indicate that adding MSW ash to organic clay has a slightly increasing effect on the unconfined compressive strengt h. The organic clay alone exhibited an unconfined compressive strength of 0.794 ps i (5.47 kPa). Addition of 10% MSW ash increased the unconfined compressive stre ngth to 0.866 psi (5.97 kPa). Adding 30% MSW ash did not cause any more signifi cant increase in stre ngth. The resulting unconfined compressive strength of the 30% MSW ash sample was 0.867 psi (5.98 kPa). Figure 5-1: Typical Failure Mode for Organic Clay-MSW Ash Blends

PAGE 43

34 Figure 5-2: Stress-str ain Curves for MSW Ash-organics Blends Direct Shear Test The direct shear test was conducted on the scrap roof shingles blended with sand. This test is provides a method for determini ng the shear strength properties and internal angle of friction for a given soil. For this test the sample is placed in a shear box with inside dimensions of 2-in by 2-in and a height of 1-in. The box is split in 2 halves top and bottom held in place with screws at each corner. The sample was placed into the shear box in 3 layers and compacted with a wooden tamper. Once the sample was compacted a normal load was applied by a lo ad hanger and the box was placed in the direct shear test machine. The two halves of the box were then separated slightly by advancing the screws. A horizont al load was top half of the box at a constant rate of 1 mm/min. The load applied to the shear box was by way of a provi ng attached to the direct shear machine. Readings were take n every minute until the proving ring readings stopped increasing meaning that the sample had failed in shear. Displacement of the top 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 00.050.10.150.20.25 Axial Strain (%)Stress (psi) 0% MSW Ash 10% MSW Ash 30% MSW Ash

PAGE 44

35 half of the box was easily calcula ted since the load was applie d at a constant rate of 1 mm/min. The direct shear test was conducted on 3 di fferent samples. The first was the sand with no shingles blended in. The second a nd third samples tested included sand blended with 5% and 10% shingles by weight, resp ectively. The samples were tested under 3 different normal loads of 35, 50, and 70 lbs. A plot of shear stress vs. displacement on the sample of sand alone is shown in Figure 5-3. Figures 5-4 and 55 show similar plots for the 5% shingles to ash and 10% shingles to ash samples. 0 1 2 3 4 5 6 7 8 9 00.050.10.150.20.250.30.350.4 Horizontal displacement (in)Shear stress (psi) N = 35 lbs N = 50 lbs N = 70 lbs Figure 5-3: Shear Stress vs. Displacement for Sand 0 1 2 3 4 5 6 00.050.10.150.20.250.30.350.4 Horizontal Displacement (in)Shear Strength (psi) N = 35 lbs N = 50 lbs N = 70 lbs Figure 5-4: Shear Stress vs. Disp lacement for Sand and 5% Shingles

PAGE 45

36 0 1 2 3 4 5 6 7 8 00.10.20.30.40.5 Horizontal Displacement (in)Shear Stress (psi) N = 35 lbs N = 50 lbs N = 70 lbs Figure 5-5: Shear Stress vs. Disp lacement for Sand and 10% Shingles It can be seen from Figures 5-3 through 5-5 that adding scrap roof shingles had a decreasing effect on the shear strength at failu re and little to no effect on the horizontal displacement of the sample at failure. For the sample of 100% sand, the peak shear stress under a normal load of 70 lbs is 8 psi and a displacement at failure of 0.35 in. When 5% scrap roof shingles are added to the sample the peak shear stress is reduced to 4.8 psi at the same displacement as the sand sample. When the amount of shingles added is increased to 10%, the peak shear stress reduced slightly to 7 psi and the displacement at failure was around 0.43 in. The direct shear test also allows for the friction angle of the soil to be determined. For the shingles-ash samples tested the friction angle determination results are shown in Figure 5-6. From Figure 5-6 it can be seen that addition of shingles to sand had a decreasing effect on the fricti on angle of sand. The 100% sand sample showed a friction angle of 300. When 5% and 10% shingles were a dded, the friction angles reduced to 280 and 25.50 respectively. Overall, the results of the direct shear test on sand blended with scrap roof shingles showed th at this material does not pr ovide any significant effects on the shear strength of sand.

PAGE 46

37 Figure 5-6: Effect of Shi ngles on Friction Angle of Sand 0 1 2 3 4 5 6 7 8 9 02468101214 Normal Stress (psi)Shear Stress (psi) 0% Shingles 5% Shingles 10% Shingles

PAGE 47

38 Chapter 6: Database Implementation Introduction Prior to the current research, many effort s have been made in trying to find other potential uses and applications for recycled ma terials. During the course of the literature review, it was found that the majority of the previous research conducted on recycled materials was published in various techni cal reports, online sources, and special publications. This makes it difficult for anyone interested in recycled materials applications to find any relevant information. As a result a project, in conjunction with the current research, was undertaken in orde r to organize all the available data on recycled materials research in a database. The database is being developed at the University of South Florida. During the literature review potion of this project, information from all of the references including journal ar ticles, conference proceedings, etc. were added to the database. This chapter will give an overview of the basic workings of the database and the process of adding and updating new data. Overview of Database The database is run using Microsoft Access software. The user is able to navigate through the database via a user fr iendly windows based in terface. The starting screen of the database, shown in Figure 6-1, allows for the user to choose one of the following options: add or update existing data, query existing da ta, or maintain the tables within the database. These in itial options allow the user to easily navigate through the database and quickly and efficiently find th e desired information. The fact that the

PAGE 48

39 database is just as easily upda table ensures that th e information taken is up to date with the most current research. Figure 6-1: Recycled Materials Relational Database Tables The data is organized within the database via different related tables that include all the relevant information collected on the original 24 materials that showed potential for reuse applications. This list of materials is shown in Table 2-1. Al ong with the list of materials, there is also a list of processes th at a specific material will undergo in order to produce a reusable form of the original material. These proc esses include a vast range of methods in which recycled materials are treate d before they can be reused in a specific reuse application. Examples of the different processes include: crushing, dewatering, drying, screening, removing of fo reign materials, etc. A portion of these processes can be seen in Figure 6-2.

PAGE 49

40 Figure 6-2: List of Pr ocesses within Database Other types of material specific information cat egories included in the database are: reuse application, engineering properties, chemi cal composition, organics content, metals content, leachate characteris tics, the state in which the re search was performed, and case studies. Each of these categories will be explained in more detail in the following sections. Reuse Applications This category includes several different pot ential applications for reusing recycled materials. For example, one of the potential reuse applications for re cycled plastic is to produce plastic lumber and use this new mate rial in a soil reinforcement/stability application. A list of the app lications included in the databa se is shown in Figure 6-3. Other applications can be adde d to the database as they ar e found in the l iterature.

PAGE 50

41 Figure 6-3: List of App lications within Database Engineering Properties This category consists of the basic en gineering properties specific to certain materials. These properties include general ge otechnical properties of the materials such as Atterberg limits (plastic and liquid limit) cohesion, and friction angle, etc. An example of the existing properties for scrap tires according to Ya ng et al., 2002, is shown in Figure 6-4. The engineering pr operties chosen to be part of the database were chosen based mostly on the ability of these properties to sufficiently describe a material. These properties are also consiste ntly reported in papers focused on civil engineering applications for recycled materials.

PAGE 51

42 Figure 6-4: Engineering Properties for Scrap Tires Material Composition and Leachate Characteristics Along with lists of materials, applicat ions, and engineering properties, the database also includes information specifi c to the chemical makeup and leachate characteristics specific to each material. Ch emical composition for the materials is given in terms of percent weight of the material. Metal and organic con centration is given in mg/kg and the leachate parameters are in mg/L A comprehensive list of all chemicals and compounds is available to characterize ea ch material. The same goes for the metal and organic concentrations. However, if a chemical compound is noted in the literature but does not exist in the database, it can be easily added by way of the table maintenance option on the starting screen. Refer to Fi gure 6-1. Figures 6-5 through 6-7 show examples of the chemical compounds, metals, and organics included in the database.

PAGE 52

43 Figure 6-5: Chemical Compounds Included within Database

PAGE 53

44 Figure 6-6: Metals Included within Database

PAGE 54

45 Figure 6-7: Organic Co mpounds within Database

PAGE 55

46 The leachate characteristics for the materi als are given in terms of the reported results of environmental tests conducted. Re sults can be found within the database for such tests as the Toxicity Characteristic L eaching Procedure (TCLP) test, the Synthetic Precipitate Procedure (SPLP), the Extraction Pr ocedure Toxicity Test, etc. The leachate tests within the database were chosen based on their ability to characterize a material as hazardous or not. Updating Database As mentioned in Chapter 1 of this report the third task of this project was the updating of the database. During the course of the literature re view, numerous journal articles and technical reports were compile d on past and present recycled materials research. The information not already include d in the database was then added by way of case studies. A case study was basically a pa per or report that entailed some form of characterization of a material that was included in original list. This section describes the basic pr ocess of inputting a case study into the database. From the start screen (refer to Figure 6-1), the “Add/Edit Existing Data” option was selected. From here the user is given the options shown in Figure 6-8. Figure 6-8: Adding Ca se Studies Process

PAGE 56

47 From here the “Case Study” option is selected and the user is now able to begin adding preliminary information such as the author or authors, a full reference to the source, year of publication, and a general overview of what the source entails. Once this preliminary information is input ted, it is saved and the user is taken to the screen shown in Figure 6-9. The screen shot shown in Figure 69 is taken from the inputted case study on scrap ti res by Yang et al., 2002. Figure 6-9: Inputting Case Study for Yang et al., 2002 At this point the user may now begin adding material specific information such as how the material is processed, what applica tion the material is being processed for, engineering properties, chemical composition etc. It is importa nt to note that for a certain material, multiple processes and applications may be chosen. This was the case for some of the materials researched where the materi al was considered for more than one reuse application or multiple materials were considered for a certain application. For example, Lee et al., 2002, recommended using a mix of fly ash and waste foundry sand as a fill of flowable back fill material. Both fly ash and waste foundry sand are also considered for reuse as separate materials. Once this information is saved, it is now available to anyone with access to the database. If the need arises for a particul ar case study to be updated, it can be accessed

PAGE 57

48 through the screen shown in Figure 6-8. Inst ead of adding a new case study, the user is able to filter through all cas e studies within the databa se by author and year of publication. Once the desired case study is select ed, the user is taken back to the screen in Figure 6-9, and the information can be updated.

PAGE 58

49 Chapter 7: Conclusions and Recommendations Conclusions General Recommendations The reuse of recycled materials in civil engineering applications is favorable because of the suitable engineering properties of the materials, the lower costs compared to traditional construction materials, and the fact that reusing thes e materials keeps them from being dumped into landfills. There are however, several issues and concerns that arise with the reusing waste materials. The biggest concerns probably are the environmental impacts associated with reusing these materials. A good majority of the materials showi ng potential for reuse (Table 2-1) come from industrial waste s ources. These materials will typically have some environmental concerns associated with reusing them in civil engineering applications. Materials such as phos phogypsum, may possess favorable engineering properties, but are not recommended for re use due to unfavorable environmental properties, namely its radioactivity. The flowchart shown in Figure 2-1 reitera tes the importance of the environmental concerns of reusing waste a nd recycled materials. Co-operation with such environmental re gulating agencies such as the Florida Department of Environmental Protection (FDEP) and the Environmental Protection Agency (EPA) is essential with reusing waste and recycled materials. FDEP requires that a Beneficial Use Demonstrati on (BUD) is conducted before a material can be reused.

PAGE 59

50 Materials Recommendations As a result of this study, it is recommended that out of the 4 materials subjected to the testing program (MSW ash, scrap tires, sc rap roof shingles, paper mill sludge), MSW ash was the only material that showed true po tential for stabilizing soils by blending. The compaction and shear strength tests conducted showed that materials such as scrap roofing shingles had either little to no effect or even detrimental effects on the geotechnical properties the so ils being stabilized. MSW ash however showed that when ble nded with soils can have positive effects with respect to compaction behavior and shear strength characteristics. During compaction testing, the addition of MSW ash to sa nd resulted in an overall increase in the maximum dry unit weight of the sa mple. This can be directly connected to an increase in strength. The same result was achieved, although less pronounced, when MSW ash was blended with a marginal soil such as the orga nic clay used in the testing program. The addition of MSW ash to the organics had a more pronounced effect on the optimum water content of the organics which decreased by nearly 20% when 30% MSW ash by weight was added. The increase in strength as a resu lt of blending soils with MSW ash is mainly attributed to the pozzolani c nature of the ash. Recommendations for Further Research Although, this study has s hown that MSW ash can ai d in stabilizing soils by blending, it also raises some que stions that need to be addr essed through further research. First and foremost is the environmental issue. A major problem with reusing MSW ash is the inconsistency of its chemical compos ition. The chemical makeup of MSW ash is variable due to the fact that the waste st ream entering the combus tion facility is not consistent. MSW ash compositi on can vary with location, t ype of combustion facility (Mass burn or RDF), and even th e time of year when the ash is collected. This variability in composition is directly related to the que stion of whether or not MSW ash should be treated as a hazardous material. If MSW ash is going to be used as a soil stabilizer, it is recommended that it is closely monitored dur ing processing and prio r to blending with

PAGE 60

51 soils in order to make sure that no hazardous materials such as heavy metals leach out and get into the groundwater. If MSW ash is recommended for use as a construction material on a given project, a report that can be accessed through the FDEP website, ent itled “Guidance for Preparing Municipal Waste-to-Energy As h Beneficial Use Demonstrat ions” provides guidelines for the user to conduct and submit a BUD to th e FDEP. The purpose of the BUD is to provide verification that the as h being reused has been managed in such a way that its application will not violate air standards or su rface or ground water standards and criteria. The BUD also ensures that the ash has been tested and monitored thoroughly prior to reuse.

PAGE 61

52 References Abichou, T., Benson, C.H., and Edil, T.B. (2002), “Foundry Green Sands as Hydraulic Barriers: Field Study.” Journal of Geotechnical and Geoenvironmental Engineering, Vol. 128, No. 3, pp. 206-215. Abichou, T., Benson, C.H., Edil, T.B., Freber, B.W. (1998), Recycled Materials in Geotechnical Applications, ASCE GSP 79, C. Vipulanandan, and D.J. Elton, Eds., pp. 86-99. Al-Rawas, A. A., (2004), “Characterization of Incinerator Ash Treated Expansive Soils,” Ground Improvement, Vol. 8, No. 3, pp. 127-135. Cabral, A. R., Tremblay, P., and Lefebvre, G. (2004), “Determination of the Diffusion Coefficient of Oxygen for a Cover System Including a Pulp and Paper By-Product,” Geotechnical Testing Journal, Vol. 27, No. 2, pp. 1-14. Chesner, W., Stein, C., Collins, R., and MacKay, M. (1998), National Cooperative Highway Research Program Waste and R ecycled Materials Information Database Accessed on July 7, 2006. http://www.rmrc.unh.edu/Resources/PandD/NCHRP Consentino, P. J., Kalajian, E. H., Heck, H. H., and Shieh, C., (1995) Developing Specifications for Waste Tires as Highway Fill Materials, FDOT Report No. FL/DOT/RMC/06650-7754. Consoli, N. C., Prietto, P. D., Carraro, J. A., and Heineck, K. S., (2001), “Behavior of Compacted Soil-Fly Ash-Carbide Lime Mixtures.” Journal of Geotechnical and Geoenvironmental Engineering, Vol. 127, No. 9, pp. 774-782. Consoli, N.C., Montardo, J.P., Prietto, P. D.M., and Pasa, G.S. (2002), “Engineering behavior of a sand reinfor ced with plastic waste,” J. of Geotech. and Geoenviron. Eng., Vol. 128, No. 6, pp. 462-472. Edil, T. B., (2005), “A Review of Mechanical and Chemical Properties of Shredded Tires and Soil Mixtures,” Geotechnical Special Publica tion, Recycled Materials in Geotechnics: Proceedings of Sessions of the ASCE Civil Engineering Conference and Exposition, No. 127, pp 1-21.

PAGE 62

53 Edil, T. B., Acosta, H. A., and Benson, C. H ., (2006) “Stabilizing Soft Fine-Grained Soils with Fly Ash,” Journal of Materials in Civil Engineering, Vol. 18, No 2., pp. 283294. Edincliler, A., Baykal, G., and Dengili, K., (2 004), “Determination of Static and Dynamic Behavior of Recycled Materials for Highways,” Resources, Conservation and Recycling, Vol. 42, pp. 223-237. Emery, J., Mangin, S., Nieuwenhuis, J. D., Or msby, W., C., Pihl, K. A., Sherwood, P. T., Toussaint, O., and van Ganse, M. R., (1977) Use of Waste Materials and ByProducts in Road Construction. Organization for Economic Co-Operation and Development, Paris, France. Foose, G. J., Benson, C. H., and Bosscher, P. J., (1996), “Sand Reinforced with Shredded Waste Tires,” Journal of Geotechnical Engineering, Vol. 122, No. 9, pp. 760-767. Ghazavi, M., “Shear Strength Characteristic s of Sand-Mixed with Granular Rubber,” (2004), Geotechnical and Geol ogical Engineering, Vol. 22, pp. 401-416. Grubb, D. G., Davis, A. F., Sands, S. C., Wartman, J., and Gallagher, P. M., (2006), “Field Evaluation of Crushed Gl ass-Dredged Material Blends,” Journal of Geotechnical and Geoenvironmental Engineering, Vol. 132, No. 5, pp. 577-590. Grubb, D. G., Gallagher, P. M., Wartman, J., and Liu Y., (2006), “Laboratory Evaluation of Crushed Glass-Dredge d Material Blends.” Journal of Geotechnical and Geoenvironmental Engineering, Vol. 132, No. 5, pp. 562-576. Hooper, F., and Marr, W. A., (2005), “E ffects of Reclaimed Asphalt Shingles on Engineering Properties of Soils,” Geotechnical Special Publication, Recycled Materials in Geotechnics: Proceedings of Sessions of the ASCE Civil Engineering Conference and Exposition, No. 127, pp 137-149. Hoyos, L. R., Puppala, A. J., and Chai nuwat, P., (2004). “Dynamic Properties of Chemically Stabilized Sulfate Rich Clay,” Journal of Geotechnical and Geoenvironmental Engineering, Vol. 130, No. 2, pp. 153-162. Iskander, M. G., and Hassan, M., (2001), “Accel erated Degradation of Recycled Plastic Piling in Aggressive Soils.” Journal of Composites for Construction, Vol. 5, No. 3, pp. 179-187. Kumar, B. R., and Sharma, R. S., (2004), “Eff ect of Fly Ash on Engi neering Properties of Expansive Soils,” Journal of Geotechnical and Ge oenvironmental Engineering, Vol. 130, No. 7, pp. 764-767.

PAGE 63

54 Kumar, S., and Stewart, J., (2003), “Evaluat ion of Illinois Pulverized Coal Combustion Dry Bottom Ash for Use in Geotechni cal Engineering Applications.” Journal of Energy Engineering, Vol. 129, No. 2, pp. 42-55. Lee, K., Yoon, Y., Cho, J., Salgado, R., Lee, and Kim, N. (2002) “Engineering Properties of Mixtures of Fly As h and Waste Foundry Sand,” Journal of Solid Waste Technology and Management, Vol. 28, No. 4, pp. 190-198. Loehr, J.E., and Bowders, J.J. (2000), “Slope stabilization with recycled plastic pins,” Geotechnical News Vol. 18, No. 1, pp. 41-44. Moo-Young, H. K., Zimmie, T. F., (1996), “Geotechnical Properties of Paper Mill Sludges for Use in Landfill Covers,” Journal of Geotechnical Engineering, Vol. 122, No. 9, pp. 768-775. Muhunthan, B., Taha, F., Said, J., (2004), “G eotechnical Engineering Properties of Incinerator Ash Mixes,” Journal of the Air and Wast e Management Association, Vol. 54, pp. 985-991. Poh, H. Y., Ghataora, G. S., and Ghazireh, N. (2006), “Soil Stabilization Using Basic Oxygen Steel Slag Fines,” Journal of Materials in Civil Engineering, Vol. 18, No. 2, pp. 229-240. Poran, C. J., and Ahtchi-Ali, F., (1988), “Pr operties of Solid Waste Incinerator Fly Ash, Journal of Geotechnical Engineering, Vol. 115, No. 8., pp. 1118-1133. Punthutaecha, K., Puppala, A. J., Vanapalli, S. K., and Inyang, H., (2006), “Volume Change Behaviors of Expansive Soils Stabil ized with Recycled Ashes and Fibers.” Journal of Materials in Civil Engineering, Vol. 18, No. 2, pp. 295-306. Quiroz, J.D., and Zimmie, T.F. (1998), “Pap er Mill Sludge Landfill Cover Construction,” Recycled Materials in Geotechnical Applications, ASCE GSP 79, C. Vipulanandan, and D.J. Elton, Eds., pp. 19-36. Reddy, K. R., and Saichek, R. E., (1998), “A ssessment of Damage to Geomembrane Liners by Shredded Scrap Tires,” Geotechnical Testing Journal GTJODJ, Vol. 21, No. 4, pp. 307-316. Show, K., Tay, J., and Goh, A. T., (2003), “Reuse of Incinerator Fly Ash in Soft Soil Stabilization,” Journal of Materials in Civil Engineering, Vol. 15, No. 4, pp. 335343. Simpson, P. T., and Zimmie, T. F., (2004), “Waste Paper Sludge-an Update on Current Technology and Reuse,” Geotechnical Special Publica tion, Recycled Materials in Geotechnics: Proceedings of Sessions of the ASCE Civil Engineering Conference and Exposition, No. 127, pp. 75-90.

PAGE 64

55 Sobhan, K., and Mashnad, M. (2003), “Fatigue Behavior of a Pavement Foundation with Recycled Aggregate and Waste HDPE Strips.” Journal of Geotechnical and Geoenvironmental Engineering, Vol. 129, No. 7, pp. 630-638. Trzebiatowski, B. D., Edil, T. B., Bens on, C. H., (2005) “Case Study of Subgrade Stabilization Using Fly Ash.” Geotechnical Special Public ation, Recycled Materials in Geotechnics: Proceedings of Sessions of the ASCE Civil Engineering Conference and Exposition, No. 127, pp 123-136. Vipulanandan, C., and Bashaeer, M. (1998) “Recycled materials for embankment construction.” Recycled Materials in Geotechnical Applications, ASCE GSP 79, C. Vipulanandan, and D.J. Elton, Eds., pp. 100-114. Wang, Y. (1999). “Utilization of recycled ca rpet waste fibers for reinforcement of concrete and soil,” J. of Polym.-Plast. Technol. Eng ., 38(3), 533-546. White, D. J., (2006), “Reclaimed Hydrated Fly Ash as a Geomaterial .” Journal of Materials in Civil Engineering, Vol. 18, No 2, pp. 206-213. Yang, S., Lohnes, R.A., and Kjartanson, B.H. (2002), "Mechanical properties of shredded tires,” Geotechnical Testing J., Vol. 25, No. 1, pp. 44-52.


xml version 1.0 encoding UTF-8 standalone no
record xmlns http:www.loc.govMARC21slim xmlns:xsi http:www.w3.org2001XMLSchema-instance xsi:schemaLocation http:www.loc.govstandardsmarcxmlschemaMARC21slim.xsd
leader nam Ka
controlfield tag 001 001910368
003 fts
005 20070927112916.0
006 m||||e|||d||||||||
007 cr mnu|||uuuuu
008 070927s2006 flu sbm 000 0 eng d
datafield ind1 8 ind2 024
subfield code a E14-SFE0001700
040
FHM
c FHM
035
(OCoLC)173366613
049
FHMM
090
TA145 (ONLINE)
1 100
Carreon, Delfin G.
0 245
Stabilization of marginal soils using recycled materials
h [electronic resource] /
by Delfin G. Carreon.
260
[Tampa, Fla] :
b University of South Florida,
2006.
3 520
ABSTRACT: Marginal soils, including loose sands, soft clays, and organics are not adequate materials for construction projects. These marginal soils do not possess valuable physical properties for construction applications. The current methods for remediation of these weak soils such as stone columns, vibro-compaction, etc. are typically expensive. Waste materials such as scrap tires, ash, and wastewater sludge, offer a cheaper method for stabilizing marginal soils. As an added benefit, utilizing waste materials in soil stabilization applications keeps these materials from being dumped into landfills, thereby saving already depleting landfill space. Included in this report is an extensive investigation into the current state of research on waste and recycled materials in construction applications. Also included is an investigation on actual implementation of this research in construction projects. Upon completion of this investigation, an effort was made to determine waste materials specific to the state of Florida (waste roofing shingles, municipal solid waste ash, waste tires, and paper mill sludge) that could be used in stabilizing marginal soils through soil mixing techniques. Changes in the engineering properties of soils as a result of adding these waste materials were studied and recommendations on implementing these effects into construction applications are offered.
502
Thesis (M.A.)--University of South Florida, 2006.
504
Includes bibliographical references.
516
Text (Electronic thesis) in PDF format.
538
System requirements: World Wide Web browser and PDF reader.
Mode of access: World Wide Web.
500
Title from PDF of title page.
Document formatted into pages; contains 55 pages.
590
Adviser: Alaa K. Ashmawy, Ph.D.
653
Waste materials.
Municipal solid waste.
Industrial by-products.
Geotechnical.
Beneficial reuse.
690
Dissertations, Academic
z USF
x Civil Engineering
Masters.
773
t USF Electronic Theses and Dissertations.
4 856
u http://digital.lib.usf.edu/?e14.1700