Innovative Use of Recycled Tyres in Civil Engineering Applic

INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONSThesis ReportUsed tyres are a major waste problem throughout the world. This project will investigate some potential uses for waste tyres in civil construction and identify advantages and disadvantages of theyre use. HES5108 Research Project Damian Ellis | Paras Gandhi Bachelor of Engineering (Civil) Supervisor: Dr Kamiran Abdouka 13th November 2009

INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09

AUTHORS

Damian EllisBachelor of Engineering (Civil) Student

Paras GandhiBachelor of Engineering (Civil) Student

Student ID Number: 5703239 Email: [email protected]

Student ID Number: 5753880 Email: [email protected]

DAMIAN ELLIS | PARAS GANDHI ii

INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 DISCLAIMER

THE AUTHORS ACCEPT NO LIABILITY WHATSOEVER FOR ANY LOSS WHICH MAY ARISE FROM ANY PERSON ACTING IN RELIANCE UPON THE CONTENTS OF THIS DOCUMENT WHERE THE WORK IS BASED ON JOINT RESEARCH, DISCLOSES THE RELATIVE CONTRIBUTION OF THE RESPECTIVE AUTHORS THIS THESIS CONTAINS NO MATERIAL WHICH HAS BEEN ACCEPTED FOR THE AWARD TO THE CANDIDATE OF ANY OTHER DEGREE OR DIPLOMA, EXCEPT WHERE DUE REFERENCES IS MADE IN THE TEXT OF THE EXAMINABLE OUTCOME. TO THE BEST OF THE CANDIDATES KNOWLEDGE CONTAINS NO MATERIAL PERVIOUSLY PUBLISHED OR WRITTEN BY ANOTHER PERSON EXCEPT WHERE DUE REFERENCE IS MADE IN THE TEXT OF THE EXAMINATION OUTCOME

NAME: DAMIAN ELLIS

NAME: PARAS GANDHI

DATE: 13TH DAY OF NOVEMBER 2009

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INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 ACKNOWLEDGEMENTS

WE WOULD LIKE TO THA THANK DEPARTMENT OF ENGINEERING AND INDUSTR INEERING INDUSTRIAL SCIENCES AT SWINBURNE UNIVERSITY OF TECHNOLOGY WHO SUPPORTED US IN OUR RESEARCH NIVERSITY TECHNOLOGY PROJECT. IN PARTICULAR WE WOU WOULD LIKE TO THANK DR. KAMIRAN ABDOUKA OF S SWINBURNE UNIVERSITY OF TECHNO TECHNOLOGY WHOM GUIDED US AND SUPPORTED US THR THROUGHOUT THE DEVELOPMENT OF THIS PROJECT. IN ADDITION, WE WOULD ALSO LIKE TO THE THANK THE FOLLOWIN ORGANISATIONS OULD THE FOLLOWING WHO KINDLY PROVIDED MATERIAL, TOOLS, EQUIPMENT, AND GENERAL ASSISTANCE IPMENT, WHICH WERE ESSENTIAL TO THE TESTING PERFORMED DURING THE COAR RMED COARSE OF THE PROJECT.

KANE Constructions Pty Transfield Services Pty Ltd Ltd Groundline Ltd

Load cell, and Associated Concrete and labour to pour concrete. Lever hoists and some Measurement Equipment, shackles round slings. and some round slings.

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INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 ABSTRACT

Used tyres are a major waste problem throughout the world. This project investigates some potential uses for waste tyres in civil construction and identifies advantages and disadvantages of theyre use. Current tyre recycling trends tend to focus on breaking down the tyres in some manner into their constituent parts. The majority of these techniques require a high input of energy, and a high investment in plant and equipment, making their products expensive, and causing significant environmental damage. While these techniques have found niche uses in various industries, a solution has not been found to adequately deal with the millions of waste tyres dumped each year, either at legal dump sites, or through illegal dumping. In light of this, this report proposes the concept of using tyres in a predominantly unmodified way (Modifications to tyre made through cutting with simple tools only), as the reinforcement and as a space filler in an example concrete beam, which was later tested to determine some preliminary mechanical properties of such a beam and to identify possible improvements to the design, and to proposed some potential uses for such a structure. Given that the concrete of the test beam was not vibrated, the beam performed as expected up to the cracking load of the beam, which was approximately 17kN. This compares with theoretical calculations for an equivalent sized hollow concrete beam (With properly vibrated concrete). Beyond cracking, the beam continued to support additional load up to approximately 25kN. Around this load, the rubber in the centre of the beam appears to have pulled out of the concrete sufficiently to cause the excessive deflection witnessed by the project team. Crushing failure of the concrete on the compression side of the beam was also noted, due to the excessive deflection. Following the testing, a number of potential uses for this type of concrete beam are proposed, in particular, it might be possible for this type of beam to be use as a railway sleeper, or as the rails of a highway crash barrier. Some preliminary calculations are performed to determine the viability of these potential uses, and it is found that the proposals warrant further investigation.

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INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 CONTENTS Authors........................................................................................................................................... ii Disclaimer...................................................................................................................................... iii Acknowledgements....................................................................................................................... iv Abstract .......................................................................................................................................... v List of Figures ................................................................................................................................ ix List of tables .................................................................................................................................. xi Introduction ................................................................................................................................... 1 Current Tyre Recycling Processes .................................................................................................. 1 Cryogenic Grinding.................................................................................................................... 2 Ambient Temperature Grinding/Shredding.............................................................................. 3 Pyrolysis (Traditional) ............................................................................................................... 4 Microwave Technique............................................................................................................... 5 Ultrasonic Technique ................................................................................................................ 5 Mechanical Properties of Tyres ..................................................................................................... 6 Use of Tyres as A Constituent of Concrete .................................................................................... 8 Tyre Rubber as an Agregate Substitute .................................................................................... 8 Tyre Steel and Fibres as Concrete Reinforcement .................................................................... 9 Use of Tyres in Civil Engineering Applications ............................................................................... 9 Properties................................................................................................................................ 10 Application .............................................................................................................................. 10 Use of un-processed tyres in civil engineering application ......................................................... 11 Reefs and breakwater ............................................................................................................. 11 Rlayground construction......................................................................................................... 11 Erosion purpose ...................................................................................................................... 12 Highway crash barriers ........................................................................................................... 12 Use of Re-Processed Tyres in Civil Engineering Applications....................................................... 12 Application of Steel: ................................................................................................................ 13 Punching of tyres (Splitting) .................................................................................................... 14

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INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 Combustion: ............................................................................................................................ 14 Pyrolysis .................................................................................................................................. 14 Conculsion .................................................................................................................................... 15 Concept of Waste Tyre Rubber Reinforced Concrete Beam........................................................ 15 Waste Tyre Rubber Reinforced Concrete Beam .......................................................................... 16 Beam Fabrication .................................................................................................................... 16 Rubber Core ........................................................................................................................ 16 Formwork ............................................................................................................................ 18 Concreting and Finalisation ................................................................................................ 19 Test Rig Fabrication................................................................................................................. 21 Design & Construction ........................................................................................................ 21 Data Logging........................................................................................................................ 22 Beam Testing........................................................................................................................... 23 Introduction ........................................................................................................................ 23 Test One .............................................................................................................................. 24 Test Sequence and Overview .......................................................................................... 24 Results ............................................................................................................................. 25 Discussion........................................................................................................................ 26 Test Two .............................................................................................................................. 28 Test Sequence and Overview .......................................................................................... 28 Results ............................................................................................................................. 29 Discussion........................................................................................................................ 33 Comparison to Equivalent Sized Beam Types ......................................................................... 36 Solid Concrete Beam ........................................................................................................... 36 Hollow Unreinforced Concrete Beam ................................................................................. 36 Steel Reinforced Solid Concrete Beam ............................................................................... 37 Future Test Recommendations ............................................................................................... 39 Costing of rubber beam or Reinforced concrete beam ............................................................... 41 Costing of reinforced concrete beam ..................................................................................... 41 Costing recycled rubber concrete beam: ................................................................................ 42 Current road safety barriers in australia:................................................................................ 43

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INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 Australian codes for road safety barriers system (AS/nzs3845, 1999) ........................................ 44 Study of NChrp 350 Report .......................................................................................................... 45 Potential Use of Rubber Tyre Cored Concrete Beams as Railway Sleepers................................. 46 Formulae & Loads Used in This Section .................................................................................. 47 Current Sleeper Designs.......................................................................................................... 48 Timber Sleepers .................................................................................................................. 48 Prestressed Concrete Sleepers ........................................................................................... 49 Steel Sleepers ...................................................................................................................... 50 Potential suitability of Rubber Core Concrete Sleeper ........................................................... 52 Use of scrap tyre in earthquake construction ............................................................................. 53 Future of usage of car-tyre rubber in earthquake construcion .............................................. 55 Discussion..................................................................................................................................... 56 Conclusion .................................................................................................................................... 57 References ................................................................................................................................... 58 Appendix DVD .............................................................................................................................. 62

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INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 LIST OF FIGURES Figure 1: Basic Modern Tyre Construction (Offroader.com 2009) ............................................... 1 Figure 2: 420um Rubber Powder (Jingdong Rubber Co., Ltd. 2009)............................................. 3 Figure 3: 0.6mm Ambient Ground Rubber (reRubber 2009) ........................................................ 3 Figure 4: Example Traditional Pyrolysis Plant (Dirk Gerlach 2009) ............................................... 5 Figure 5: Tread Ring Stress vs Strain (Turer & Glal 2008)......................................................... 6 Figure 6: Tread Ring Load vs Displacement (Turer & Glal 2008) .............................................. 6 Figure 8: Cross section of various tyres treads ............................................................................. 7 Figure 7: Tyre tread ring................................................................................................................ 7 Figure 9: Tyres were dumped in 1970s in an attempt to establish an artificial reef. ................. 11 Figure 10 Wire mesh and Bead separated from Tyre ................................................................. 13 Figure 11: Tread Section of Rubber Tyre as used in the Conceptual Beam. ............................... 17 Figure 12: Rubber Beam Flexibility ............................................................................................. 18 Figure 13: Formwork with rubber core in place ......................................................................... 19 Figure 14: Completed beam upon delivery at test location ....................................................... 20 Figure 15: Completed Test Rig .................................................................................................... 22 Figure 16: Beam Load vs. Time (Test One).................................................................................. 24 Figure 17: Initial Crack in Beam (0kN Load on Beam) ................................................................. 25 Figure 18: Cracking Event (Test One) .......................................................................................... 26 Figure 19: Beam Load vs. Time (Test Two) ................................................................................. 28 Figure 20: Beam Under Load During Second Test (13.695kN Beam Load) ................................. 29 Figure 21: Crack Event at 20kN ................................................................................................... 30 Figure 22: Evidence of Crushing Failure of the Beam (Compression Face) ................................ 31 Figure 23: Rubber Tyres Inside Crack (21.215kN Beam Load, 1st 25kN load cycle) ................... 32 Figure 24: Rubber Tyres Inside Crack (20.849kN Beam Load, 2nd 25kN load cycle) .................. 32 Figure 25: Beam deflection due to Self Weight .......................................................................... 33 Figure 26: Load vs Deflection (Both Tests).................................................................................. 34 Figure 27: Damage Sustained by Beam (Bottom (Floor) Face) ................................................... 35 Figure 28: Damage Sustained by Beam (Tension Face) .............................................................. 35

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INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 Figure 29: Beam Deflection at End of Test Two (Beam Load 20.760kN) .................................... 40 Figure 31 Flexfence 4 Rope Type product of INGAL CIVIL .......................................................... 43 Figure 30 Picture of Typical Freeway (Highway Barrier Solutions UK). ...................................... 43 Figure 32 T-39 Thribeam Type Product of INGAL CIVIL .............................................................. 44 Figure 33 Recommended test summary sheet for crash test results as per NCHRP report 350 report, on page number 58 and onwards. .................................................................................. 46 Figure 34 Steel Sleeper Dimensions (OneSteel, 2002)................................................................ 51 Figure 35 Plan section of with reinforced car tyre strips showing internal tensions and compression areas. (Charleson 2005)......................................................................................... 53 Figure 36 Nail Bending Pattern (Charleson 2005)....................................................................... 54 Figure 37 Experiment trial arrangement for applying load on specimen without tyres. (Charleson 2005) ......................................................................................................................... 54 Figure 38 Tyres wrapped at the half wall height at corner (Charleson 2005) ............................ 55

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INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 LIST OF TABLES Table 1: Engineering properties of tyre rubber from Development of crumb Rubber Materials from Whole Tyre BY Michael W. Rouse....................................................................................... 10 Table 2: Details of tyre used in the concrete beam rubber core. ............................................... 16 Table 3: Concrete Beam Mass Estimates .................................................................................... 20 Table 4: Theoretical Cracking Load for Rubber Beam (Ignoring Effect of Rubber)..................... 27 Table 5: Capacity Calculations: Solid concrete beam ................................................................. 36 Table 6: Capacity Calculations, Hollow unreinforced concrete beam ........................................ 37 Table 7: Capacity Calculations, Steel Reinforced Concrete Beam .............................................. 38 Table 8: Current Concrete Prices ................................................................................................ 41 Table 9 Pricing Comparison for RCC Beam & Rubber Concrete Beam with considering the dimension 0.27x0.20x1.80 .......................................................................................................... 42 Table 10: Road Safety Barrier Testing Conditions....................................................................... 45 Table 11: Legend of Vehicle Codes for Table 10 ......................................................................... 45 Table 12: Formulae Used for Calculating Railway Sleeper Bending Moments ........................... 47 Table 13: Timber Sleeper Properties .......................................................................................... 48 Table 14: Concrete Sleeper Properties ....................................................................................... 49 Table 15: Steel Sleeper Properties .............................................................................................. 50 Table 16: Rubber Core Concrete Sleeper Properties .................................................................. 52

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INTRODUCTION

The overall aim of this research project is to determine the feasibility of utilising generally unprocessed waste tyres in novel ways in civil engineering applications. In order to achieve tyres this, it is necessary to first analyse previously published knowledge relating to the research ary topic in the following area: Tyre recycling processes. Mechanical properties of tyres. Previously researched uses for waste tyre rubber and other tyre material in civil engineering applications. The following literature review will summarise key research papers and other information sources relating to the above three sub sub-topics, which will allow for more detailed analysis of the feasibility of potentia civil engineering applications for waste tyre identified during the potential tyres course of this research project.

CURRENT TYRE RECYCLING PROCESSES

According

to

Williams

(2007) the importance of rubber (tyre) recycling was ) realised as far back as the initial discovery in by and of 1839 Charles Thomas

vulcanisation separately Goodyear

Hancock. However, a viable . recycling technique wasnt described until 1899 by Arthur Marks, , whoFigure 1: Basic Modern Tyre Construction (Offroader.com 2009) :

patented his alkali process,

which remained in use well into the 20th century (Williams, 2007). This statement is supported in principal by Turer & Glal (2008). The authors state that approximately half of the tyres

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INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 produced until the 1960s were recycled. This was due to both natural and synthetic rubbers being expensive at the time. In addition, tyres in this period were manufactured from rubber (Natural or synthetic, or a mixture of both), only and were therefore comparatively easy to recycle. The development of steel belted tyres in the late 1960s was almost the end of tyre recycling. By 1995, only 2% of the rubber was being recycled. (Turer 2008). In slight contrast, Adhikari & Maiti (2000) state that in the early 1900s, 50% of rubber in use was from reclaimed sources, this reduced to approximately 20% at the end of the 1950s and continued to decline until in the mid-1980s only 1% of rubber was recycled. Whilst there is a small discrepancy in the figures between Adhikari & Maiti (2000) and Turer & Glal (2008), the fundamental message from the authors is that there has been a significant decline in the amount of rubber being recycled since the early to mid 20th century to a point in the mid 1980s when rubber recycling was almost non-existent. While neither of the authors states it, based on a comparison of these percentages between both of the authors, one could suggest that since the mid 1980s there has been a slight increase in rubber recycling (Based on Turer & Glals (2008) statement that 2% of rubber was being recycled in 1995). This decline notwithstanding, there have been a number of techniques proposed to recycle tyre rubber and other constituent materials of modern tyres. Some of which are described below.

CRYOGENIC GRINDING

The process of grinding scrap rubber into a fine powder by first cryogenically cooling the rubber using liquid nitrogen was first described in the mid 1960s (Klingensmith 1991). Klingensmith (1991) describes the process as involving small pieces (25mm x 25mm x 12mm) of rubber being placed in liquid nitrogen and ground into a fine powder of particle sizes of between 590m and 149m. Eldin & Senoucis (1993) and Pilakoutass et al. (2004) descriptions of the process compare in principal with Klingensmiths (1991) description of the process. Pilakoutas et al. (2004) adds that the rubber is pre-cooled using nitrogen gas at a temperature of approximately -120C (153K) before the rubber enters the main cooling tunnel, where it is cooled to below its embrittling or glass transition temperature. Eldin & Senouci (1993) draw the conclusion that cryogenic grinding is a good technique for

extracting/separating the steel and fabric from tyres; however, it is expensive compared with ambient temperature grinding. In contrast, Pilakoutas et al. (2004) draws the conclusion that cryogenic grinding is an energy-efficient solution compared with ambient temperature grinding, as it requires less energy to separate the rubber from other tyre material. This may be true if one does not take into account the embodied energy within the liquid nitrogen used DAMIAN ELLIS | PARAS GANDHI 2

INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 to cool the rubber. However, it is difficult to believe that a technique which requires the consumption of such an energy intensive product as liquid nitrogen is overall more energy efficient than ambient temperature grinding. ent

Figure 2: 420um Rubber Powder (Jingdong Rubber Co., Ltd. : 2009)

Figure 3: 0.6mm Ambient Ground Rubber (reRubber 2009) :

AMBIENT TEMPERATURE GRINDING/SHREDDING

Ambient temperature grinding/shredding produces courser rubber particles then cryogenic mperature grinding. The manner in which the rubber particles are produced also differs somewhat between ambient temperature and cryogenic grinding. Jang et al. (1998) contrasts t modes the of particle production by stating that for ambient temperature grinding particle reduction is accomplished by tearing or shearing action ( (Jang et al. 1998) where as when cryogenically cooled particles are reduced by fracturing the rubber. In contrast to cryogenic grinding, contrast ambient temperature grinding produces particle sizes in the order of 0.6mm to 2mm. Klingensmith (1991) & et al. (1998) Jang et al. (1998), and Weber et al. (2008) all generally (1998), agree on this particle size, however, Jang et al. (1998) states a slightly wider range of particle sizes of 0.422mm to 6.35mm. Pilakoutas et al. (2004) identifies ambient temperature grinding as a commercially mature and reliable process. The authors also identify that the use of this technique has increased in recent years as it is more economical to transport shredded tyres ased rather than whole tyre (Pilakoutas et al. 2004). Ambient temperature grinding is also tyres identified as potentially quite expensive by Pilakoutas et al. (2004). H However, in contrast to this Eldin & Senouci (1993) state that ambient temperature grinding is significantly cheaper than cryogenic grinding Klingensmith et al. (1998) also agrees that ambient temperature grinding. grinding is a relatively inexpensive technique. Given the embodied ener in the liquid energy DAMIAN ELLIS | PARAS GANDHI 3

INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 nitrogen used in the cryogenic process and the cost of that energy, this paper would tend to agree with Eldin & Senouci (1993) and Klingensmith et al. (1998) over the Pilakoutas et al. (2004) paper. Excess heat due to friction in the grinding process is identified by Klingensmith

(1991) & et al. (1998) as an issue inherent in this technique, where in some instances, temperatures can increase enough to cause degradation of the rubber being ground and/or cause combustion of stored rubber subsequent to grinding.

PYROLYSIS (TRADITIONAL)

Pyrolysis involves decomposing tyres in the absence of oxygen using heat. This technique was first described in the late 1960s by Wolfson et al. according to Eldin & Senouci (1993). The process is identified as largely unsuccessful due to unfavourable economies (Jang et al. 1998). Pilakoutas et al. (2004) describes that process as energy efficient, as the gasses and oils obtained from the process can be used to produce the energy required for the process. This is reasonable conclusion to draw; however seems to defeat the purpose of processing the tyres in the first place, since much of the valuable derived material such as crude oil is combusted to produce the energy for the process. It seems much more viable to simply combust the tyres in a power plant to produce electrical energy for the community or in kilns to produce heat for other manufacturing processes. Ferrer (1997) and Jang et al. (1998) both identify tyre rubber as having a slightly higher heat value than coal. However, there are significant environmental issues relating to combustion of rubber which require sophisticated high-temperature combustion facilities (Jang et al. 1998). Both Eldin & Senouci (1993) and Pilakoutas et al. (2004) conclude that pyrolysis using traditional heating techniques is not an economically viable solution to recycling tyres.



Figure 4: Example Traditional Pyrolysis Plant (Dirk Gerlach 2009)

MICROWAVE TECHNIQUE

The microwave technique decomposes rubber in much the same mode as the traditional pyrolysis technique described above Adhikari & Maiti (2000) describe the technique as using above. a controlled dose of microwave energy at specified frequency and energy level in an amount sufficient to cleave carbon carbon bonds. Whereas similarly Pilakoutas et al. (2004) describes fficient carbon-carbon the process as using optimised microwave power at the molecular level to thermally decompose tyres. Both papers conclude that the microwave technique is more en s. energy efficient and more environmentally friendly than traditional pyrolysis. However, again, Pilakoutas et al. (2004) states that the gasses produced in the process can be used to service the energy requirements of the technique, which seems to partially defeat the purpose. defeat

ULTRASONIC TECHNIQUE

Klingensmith & Baranwal (1998) describe the ultrasonic technique as devulcanization. The technique involves exposing crumb rubber from waste tyres to high intensity ultrasonic s vibrations which are absorbed by the rubber which is theorised to fracture the sulphur rubber sulphur-sulphur bonds which produces a rubber which can be reprocessed back into virgin rubber and re re-cured (Klingensmith & Baranwal 1998). Further detail on this technique is described in a paper by Adikari & Maiti (2000). In contrast to Klingensmith & Baranwal (1998) the authors state that (2000). DAMIAN ELLIS | PARAS GANDHI 5

INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 solid rubber articles such as tyres as immersed in liquid and exposed to ultrasonic vibrations s of between 20kHz and 50kHz with an intensity of 100W. The authors state that 20 minutes of exposure is required to devulcanise the rubber. While the ultrasonic technique appears to be the most energy efficient technique for recovering reusable rubber from waste tyres, and the nergy recovered rubber seems to have properties such that it could be used in most applications where virgin rubber is used, there is still a significant input of energy required to complete the process. Adikari & Maiti (2000) states, the devulcanisation process requires a high energy level to break carbon-sulphur and sulphur sulphur sulphur-sulphur bonds.

MECHANICAL PROPERTIE OF TYRES PROPERTIES

Experiments were conducted by Turer & Glal (2008) to determine the tensile strength of tyre rubber. Initial testing proved disappointing with failure of the tyre strip at

approximately 35kN. This was due to the test specimen tearing and slipping out of the clamp holding it.Figure 6: Tread Ring Load vs Displacement (Turer & Glal 2008)

Subsequent to a redesign of the testing apparatus, the authors found that the tread rings of tyres have an ultimate tensile strength of between 90kN and 190kN, with an average of 133.4kN and a standard deviation of 31.7kN or 24% (Turer & Glal 2008) 2008). The authors also found that the average stiffness of the tested tyres was

Figure 5: Tread Ring Stress vs Strain (Turer & Glal 2008)

2.93kN/mm and average ultimate stress .93kN/mm of 34.3MPa. Analysis of the stress strain curve the authors produced yielded an elastic stress-strain modulus of between 500MPa and 1200MPa.


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 Turer & Glal (2008) surmise that the following factors will affect the tensile capacity of a tread ring: he ring. The amount, orientation and tensile capacity of the steel strands within the tread ring The cross-sectional area of the tread ring. sectional The softness of the rubber blend in the tread ring. The age of the tread ring, and the amount of exposure it has had to the sun. The authors also conducted tensile tests on the tyre bead wire and found the yield capacity of the bead wire to be in the order of 2130MPa. This figure compares well with Papakonstantinou & Tobolski (2006) who state the yield capacity of the bead wire as being between 1500MPa and 1900MPa.Figure 7: Tyre tread ring :

Figure 8: Cross section of various tyres treads


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 USE OF TYRES AS A CONSTITUENT OF CONCRETE

A number of researcher in the past twenty years have investigated the possibility of utilising waste tyres and/or materials recovered from waste tyres as constituents of concrete, either through substitution of normal concrete materials, such as course or fine aggregate, or as concrete reinforcing materials.

TYRE RUBBER AS AN AGREGATE SUBSTITUTE

Beginning in the early 1990s a number of researchers have investigated the possibility of utilising waste tyres in various forms as a substitute for either the course or fine aggregate in concrete. Eldin & Senouci (1993) investigated the properties of at 35MPa GP concrete with the course aggregate replaced with rubber tyre particles, and also the same concrete with rubber tyre particles substituting the fine aggregate over various percentages of total aggregate volume. The authors found that there was a significant reduction in compressive and tensile strength of concrete which contained rubber particles. The worst performing specimens, which contained 100% rubber tyre particles as course aggregate, having lost 85% and 50% of their compressive and tensile strength respectively compared with the control specimens which contained no rubber. This compares with results from similar studies undertaken by Batayneh et al. (2008), Ganjian et al. (2009), Yilmaz & Degirmenci (2009), Meyer (2009), and Oikonomou & Mavridou (2009) All of whom witnessed reductions in strengths comparable to Eldin & Senoucis (1993) results. This reduction in strength was also noted by Siddique & Naik (2004) in a literature survey the authors undertook investigating the use of tyre rubber as concrete aggregate. Findings from the above studies indicate that rubber fill concrete does not experience brittle failure; rather it fails in a ductile mode (Eldin & Senouci 1993). Batayneh et al. (2008) stated that it is not recommended to use this modified concrete in structural elements were high strength is required. Similar sentiments are noted by Eldin & Senouci (1993), Siddique & Naik (2004), and Oikonomou & Mavridou (2009). However, many of the authors note that concrete modified with waste tyre rubber could be used in such low stress applications such as non-structural facades, highway crash barriers, due to the concretes superior impact resistance, sound absorbing panels due to the concretes improved sound attenuation properties (), or in driveways and roadways (Eldin & Senouci (1993), Siddique & Naik (2004), Batayneh et al. (2008), and Oikonomou & Mavridou (2009)).


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 TYRE STEEL AND FIBRES AS CONCRETE REINFORCEMENT

In addition to research being undertaken into using rubber as an aggregate substitute, some researchers have also investigated the possibility of using the steel and other fibres from recycled tyres as concrete reinforcement. This is predominantly due to the presents of high strength steel fibres within modern tyres. Pilakoutas et al. (2004) investigated the use of tyre steel fibres as concrete reinforcement by comparing steel fibres recovered from tyres using the shredding/cryogenic grinding process and fibres obtained from the microwave process. The authors found that the strength of fibres recovered using both techniques was best utilised at fibre lengths of 20mm for fibres recovered from shredding and 20mm for fibres recovered from the microwave process. The authors state that this is comparable to equivalent industrial reinforcement fibres. It was also found that the ideal fibre content in concrete by weight is 6% for fibres recovered from the microwave process and 2% from shredding. Wang et al. (2000) investigated the use of various different fibres as reinforcement in concrete from a shrinkage point of view. As part of the authors study, both fabric and steel fibres recovered from waste tyres were analysed. The authors found that the shrinkage of the concrete specimen containing tyre steel fibres compared with the shrinkage of the control specimen and shrinkage of specimens containing tyre fabric fibres was 23-57% higher than the control specimen (Wang et al. 2000). The authors also found that the use of recycled tyre fibres (both steel and fabric) improved shrinkage crack widths compared to the test specimen, however, the improvement was not as significant as the improvement gained from the use of industrial steel fibre reinforcement products. Papakonstantinou and Tobolski (2006) Also investigated the use of steel fibres recovered from waste tyres, however, in their study the authors focussed on steel fibres recovered from the tyre bead. The authors found that generally, the addition of tyre steel beads reduces the compressive strength of the test specimens, however markedly improved ductility (by 20% compared with the control specimens), and toughness of the test specimens containing tyre beads.

USE OF TYRES IN CIVIL ENGINEERING APPLICATIONS

The use of recycled tyres saves valuable energy and resources. A new tyre requires 23L of crude oil equivalent for raw materials and 9L for process energy compared with 7L and 2L respectively for recycling. (Research Journal of Recycling Rubber by Practical Action, The Schumacher Center For Technology & Development)


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 PROPERTIES

Tyres have many properties that can be taken advantage of when the scrap tyre is converted in Tyre Derived Material. It is important to understand and analyse the engineering properties of tyre rubber for further understanding of the application of tyres in civil engineering application. There are some engineering properties as listed below with respective feature:Table 1: Engineering properties of tyre rubber from Development of crumb Rubber Materials from Whole Tyre BY Michael W. Rouse

Property Black Liquid State Low Density Water Resistant Low Thermal Conductivity Low Electrical conductivity Absorption Rheology Enthalpy Organic APPLICATION

Feature Opaque Low Freezing point Specific Gravity 1.12 to 1.15 Non wicking Thermal Barrier Insulator High absorption of most organic liquids Elastic, compliant, and resilient High heat of combustion and low ash content Non biodegradable

The tyre is nearly indestructible to normal mechanical fracturing mechanisms. Further if the different components like fibre, rubber and steel are separated than they can be used for different purposes. Further it can be divided by two parts with the application of recycled rubber; first one rubber tyre used directly without processing and second rubber tyre used with the factory processes. Further it is also mentioned that materials made from tyres are called tyre-derived materials (TDMS) and include a higher portion, crumb rubber materials (CRMS) which can be reused in the manufacture of tyre compounds and for many other applications. (Rubber Recycling, Sadhan K. De., A. I. Isayev, K. Khait 2005) In general, the scrap tyre processor must have a number of applications, markets, to survive and be viable. The scrap tyre plant can be designed to produce a variety of Tyre Derived Material. There are certain applications which does not need any kind of processing or which need normal processing. Further there are some applications which needs over processing. By limiting the process the cost of end product could be in control and saves large amount of


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 energy. Further application of recycled tyre will be divided in two sections as processed and unprocessed recycle use of tyre.

USE OF UN-PROCESSED TYRES IN CIVIL ENGINEERING APPLICATION PROCESSED NG

REEFS AND BREAKWATER EEFS

Reefs: When it come to application of building a reef out of recycled tyre tyres the first example some can think will the project of Fort Lauderdale at Florida in United States of America. That project alone has used 3 million tyres s and it wasFigure 9: Tyres were dumped in 1970s in an attempt to establish an artificial reef. s

projected that project will add 1 million tyre

every year. In the present scenario it is estimated that 120,000 to 150,000 tyres are annually estimated used in the construction of reefs in United States of America. The costing of building a reef of discarded tyres cost around approximately 3.5 USD per tyre. s Break-Water: One of the applications of the scrap tyre is also to construct a break Water: break-water. Discarded tyres used for constructing breakwater are filled with foam and which displaces s for approximately 91 kg of water. Tyres float cost around 0.06USD to 0.08 USD per 0.13kg to 0.18kg. But later it was founded that it is economical to use foam with plastic and it cuts off the price 20% to 30%.

RLAYGROUND CONSTRUCTI LAYGROUND CONSTRUCTION

There was a concept found out constructing playground from the discarded tyres in early 1990s and same for the recreational area. It was also estimated in the American book Conservation and Recycling published in 1998 by Jang et al. that 7500 tyre are used every year tyres in USA for the construction from discarded tyres. This application for using of recycled tyres is on DAMIAN ELLIS | PARAS GANDHI 11

INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 decreasing as economy is improving and school and parks are selecting wooden playground base for better ambience.

EROSION PURPOSE

It is usual practice around the world to bury tyres or practice illegal land filling. But use of scrap tyres as a Soil Erosion Control was tested and designed by The California Office of Transportation Research. Discarded tyres were tied together partially or completely and further buried on unstable slope. By doing such practice construction price can be reduced. It was also estimated that construction cost and cut down by 505 to 75% in comparison of rock, gabion or concrete protection.

HIGHWAY CRASH BARRIERS

In late 1970s study was undertaken by Texas Transportation Unit for the application of use of discarded tyres as a highway crash barrier. It was also discovered stack of tyre tied up with a steel cable or enclosed within fibre glass absorbs or helps to reduce the impact of automobiles travelling up 115km/hr. Apparently State Transportation Departments in United States Of America prefers sand-filled crash barriers because they have better absorption properties and easier to construct on site.

USE OF RE-PROCESSED TYRES IN CIVIL ENGINEERING APPLICATIONS

Scrap tyres may be split, punched or stamped to yield shapes suitable for fabrication, or discarded tyres may to process to produce shred pieces which is called crumb in market. Tyres may be processed and force them into powder form which can be used in to rubber or plastic product, some rail road crossing or for asphalt paving. Various rubber products can be manufactured using rubber from discarded tyres to replace some virgin rubber is production of different variety of rubber products. During research for the recycled used of tyres we observed that market of recycled tyres is constantly developing. There are various uses and application of processed tyres. By saying the processed recycled tyres it means that with the help of either chemically or mechanical process every component of tyre is separated and is used individually. In the present market there are few applications for the processed tyres. There are few processes as listed below: DAMIAN ELLIS | PARAS GANDHI 12

INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 1. Tyre Rubber Recycling by Mechano Mechano-chemical Processing 2. Recycling by High Pre Pressure and high temperature Sintering. 3. Rubber Recycling by Blending with Plastic 4. Ultrasonic Devulcanization 5. Devulcanization by chemical and Thermo Thermo-mechanical means 6. Conversation of used tyres to Carbon Black and Oil.

APPLICATION OF STEEL STEEL:

The removal of inherent steel and reinforcing cords, either radial or bead wires, in the tyre carcass is one of the greatest concern. Usually magnet machine are used for removal of steel and aluminium products out of the CRM. When an object is surrounded b a magnetic field by and has magnetic properties, either natural or induced, it attracts iron or steel. Nonferrous materials like aluminium and copper can be removed with the help of that machinery but in rare case those metals are found unless and until they are contaminated by their original they source. After wire mesh or steel powder collected from CRM it is used for various purposes such as industrial, automobile etc. It was also derived that steel which is used as a wire mesh in tyres in capable for 1000 MPa to 1200 MPa s Further with the help of machine steel bead is separated from sidewalls and which may be machine, reused for construction purpose or recycled again for production of steel.

Figure 10 Wire mesh and Bead separated from Tyre


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 PUNCHING OF TYRES (SPLITTING)

The complete process involves the removal of steel bead and then the desired shaped is achieved using stamp or punch. There are many products which are available in market made up from this process like floor mats, belts, gasket, shoe soles, dock bumpers, seals, muffler hangers, shims, washer, insulators, and finishing and farming equipment. Because this industry is diversified there are no extensive published data; it is difficult to make good estimates of worldwide usage of split rubber products.

COMBUSTION:

Scrap tyres have potential in itself as energy value. There are various applications of discarded tyres as a fuel for the power plant, cement kilns, for pulp and paper mills and mainly for tyre manufacturing process. It is mentioned in Discarded tyre recycling practices in the United States of America, Japan and Korea which is an American Journal published in year 1998 that discarded tyres have fuel value slightly higher than that of coal, about 12,000 to 16,000 Btu (6,660 to 8,800 K.cal/kg) per pound. It is also recommended that combustion of one tyre cost less than process tyre for getting shredded pieces of scrap tyre. Further main drawback of this application is that, that the emission at the end of process has to be in its limit i.e. the emission has to be in environmental limits and efficiency of equipments used for the combustion has to be of superior quality. Further it is usual practices that tyre are firstly process in shredded form than they are burnt to produce fuel. The logical reason was doing such practice is to overcome transportation cost of whole tyre to power plant.

PYROLYSIS

This application is mostly failure around the world. Researchers recommend the reason of failure is that, that his application involves consumption of heat energy to derive various products such as carbon black and oil. The cost of heat energy is fairly high than the cost of process of production oil from crude. This application may be successful in future when crude price may rise. The remains of steel-belted tyres and char by-products and among those mainly steel wires are problem of pyrolysis of tyres.


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 CONCULSION

Because of some failed ideas for the use of recycle tyres the there are huge amounts of tyres accumulated around the world. It is been concluded from the research which has been done until now and from the market that the world is moving towards disposing tyres by using them various processed or unprocessed applications. It is been also concluded that, highways system are the place where the recycled tyres can be used as a crash barriers and also for the sound barriers on freeways. It is also been concluded that rubber used in tyres has the achievable acoustic strength and can absorb the sound from the vehicles on freeway. Highways provide an excellent place to use discarded tyres as an alternative to landfill disposal. Further still there are many technical problems needs to be solved i.e. further research is required in those field.

CONCEPT OF WASTE TYRE RUBBER REINFORCED CONCRETE BEAM

Following the literature review it was identified that most current recycling techniques for waste tyres required high energy input. After a deep study of the present trends of the use of recycled tyres, our research team came to a conclusion that there is a lack of recycling methods that requires minimum amount of energy to modify tyres such that they are suitable for civil engineering applications. We observed that scrap tyres are currently used as a filler material in some applications however, we identified that scrap tyres may have enough remaining strength which might be suitable for certain structural applications. In light of this, it was decided to develop the concept of using waste tyres for reinforcement in concrete beams which may be useful in applications such as non-load bearing beams, railway sleepers and highway crash barriers. In future rubber reinforced concrete beams may be a viable alternative to present steel rope barriers or Thribeam (W-Beam) crash barrier. The high impact absorption properties and high deflection qualities could be beneficial in the crash barriers concept. With further development rubber cored concrete sleepers may be used in place of currently used prestressed concrete sleepers or timber sleepers. The use of waste tyres in concrete sleepers will likely lead to a more cost effective, longer life span and environmentally friendly sleeper design.


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 WASTE TYRE RUBBER REINFORCED CONCRETE BEAM

During development of this project it was decided to fabricate a conceptual waste tyre rubber reinforced concrete beam to conduct some load testing on to determine the possible performance of a beam reinforced with waste tyre rubber. The following is a detailed commentary on the full development process.

BEAM FABRICATION

RUBBER CORE The rubber core was fabricated from the tread section of waste tyres. The tyres used were steel belted radial type tyres which contain steel strands that run within the rubber of the tread around the circumference of the tyre to strengthen it (See Figure 11). All tyres used in the rubber core were worn to or below the wear indicator moulded into the treads. All tyres except one were 175/70R13 with the other being 165/75R13. All tyres except one had a weight code of 82, the other tyre had a weight code of 81. Eight of the tyres had a speed code of H, one had a speed code of S and one had a speed code of T. The details of each tyre utilised are given below:Table 2: Details of tyre used in the concrete beam rubber core.

Tyre Code No. Tyres Width Height (Edge of rim to tread) Construction Rim diameter Load Rating Speed Rating

Simex SM800 175/70R13 82H 1 175mm 0.70 x 175 = 122.5mm Radial 13 inch = 330.2mm 82 = 475kg H = 210km/h

(No Name) Classic 70 175/70R13 82T 2 175mm 0.70 x 175 = 122.5mm Radial 13 inch = 330.2mm 82 = 475kg T = 190km/h

Bridgestone Turanza ER592 175/70R13 82H 3 175mm 0.70 x 175 = 122.5mm Radial 13 inch = 330.2mm 82 = 475kg H = 210km/h

Bridgestone B249 165/75R13 81S 1 165mm 0.75 x 165 = 123.75mm Radial 13 inch = 330.2mm 81 = 462kg S = 180km/h

Michelin Certis 175/70R13 82H 1 175mm 0.70 x 175 = 122.5mm Radial 13 inch = 330.2mm 82 = 475kg H= 210km/h


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 Tyres were cut around both edges of the tread ring to separate the tyre side walls and beads s from the tread ring. An electric jigsaw with a hacksaw blade attachment was used to cut the tyres. The remaining tread rings were then cut across the tread using the same jigsaw. This s. created a rubber tread strip of approximately 1700x170x10mm. Eight tyres were cut in this 1700x170x10mm. manner to create eight plies. It was noted during cutting that the Bridgestone and Michelin tyres were slightly harder to cut than the Simex and (No Name) tyre This likely indicates a s tyres. greater number and/or stronger steel threads used in the name-brand tyres over the nonbrand name-brand tyres. Every different tyre was having different level of boldness. Some the s. specimen tyres were completely bold and edges and were not having any texture left. s

Figure 11: Tread Section of Rubber Tyre as used in the Conceptual Beam.

The eight tread strips (plies) were formed into a rubber block approximately 170x90mm. The plies were laid in an alternating arrangement with one ply laid with the tread facing down and the next ply laid with the tread facing up. This arrangement was intended to prevent the completed rubber block from maintaining a partial curve due to the original molded shape of the plies. Initially the treads were fixed together using steel straps which were bolted through the small holes in the strapping. However, this fixing system was not capable of being tensioned adequately to bond the treads together tightly. Steel wire was then used to fix the treads together which allowed for some post tensioning of the wire subsequent to the wire tensioning being tied around the treads. This allowed the plies to be tightly bound together; however the block remained overly flexible, as can be seen in Figure 12. This appeared to be due to: . 1. The plies sliding against one and other 2. The plies deforming in between each wire tie.


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 To try and reduce the deformation and better bond the plies together, chipboard screws were driven into the plies at even spacing at the top and bottom of both sides of the beam. In key s locations additional screws were driven into the plies. This significantly improved the stiffness of the rubber beam.

FORMWORK The formwork was designed to allow the entire assembly to be transported with or without concrete, and to also allow the concrete to be poured in any location without any on site preparation (See Figure 13). The formwork was fabricated from particle board with MGP10 reinforcement. The rubber core was secured in the centre of the formwork by sitting it on 50mm reinforcement chairs below the rubber and by tying the rubber to the sides of the formwork using steel wi as was used to tie the tyre plies of the rubber core together. Wood wire, and chipboard screws were used to secure the formwork together and to allow it to be stripped away from the completed beam. The inside surfaces of the formwork were lubricated to prevent the concrete from bonding to the formwork. nt

Figure 12: Rubber Beam Flexibility



Figure 13: Formwork with rubber core in place

CONCRETING AND FINAL FINALISATION The completed formwork was transported to the concrete pour location at Swinburne University Advanced Technology Centre (ATC) construction site. Concrete was supplied by Boral Concrete through Kane Constructions during one of their scheduled pours for the ATC. The concrete used was 32MPa GP concrete. As the pour location was within an operating concrete. construction site, due to safety issues and the requirement for visitors to be inducted onto the construction site, it was not possible for the project team to be onsite during the pour. The completed concrete beam was collected from the pour location approximately five days after the pour and was transported to the testing location at one of the project members house. Upon delivering the beam to the testing location, the formwork was removed. It was noted that the concrete did not appear to have been vibrated nor did it appear to have been oted covered with wet coverings or had a curing compound applied. However, the concrete appears to have cured adequately and there was no evidence of shrinkage cracking. The concrete appeared to be acceptably poured and was adequate for testing. The beam was weighed at 206kg using a load cell. This agrees well with the estimated mass of the beam of 215kg, calculated as follows:


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09Table 3: Concrete Beam Mass Estimates

Beam Type Solid Concrete Steel Reinforced Concrete (Concrete) Steel Reinforced Concrete (Steel) Steel Reinforced Concrete (Total) Rubber Cored Concrete Beam (Concrete) Rubber Cored Concrete Beam (Rubber) Rubber Cored Concrete Beam (Total)

Volume (m3) 0.27x0.20x1.80 = 0.097 (0.27x0.2x1.8)-0.006 = 0.091 0.006

Unit Mass (kg/m3) 2500 2500 7800

Total Mass (kg) 243 229 42 270

(0.27x0.20x1.80) (0.17x0.10x1.70) = 0.068 0.17x0.10x1.70 = 0.29

2500 1522

171 44 215

The likely reasons for the disparity between the actual and calculated mass are as follows: Air voids within the rubber core (In between plies) Air entrainment within the concrete

The mass of the rubber cored beam is significantly less than that of an equivalent solid concrete beam with a mass saving of approximately 37kg. This equates to a mass saving over te an equivalent solid concrete beam of approximately 15%. Compared to a steel reinforced concrete beam of equivalent size, the mass saving is more pronounced with a mass sav saving of approximately 64kg. This equates to a mass saving over an equivalent sized steel reinforced concrete beam of approximately 24%.

Figure 14: Completed beam upon delivery at test location


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 TEST RIG FABRICATION

To test the beam at the selected test location it was necessary to fabricate a test rig which would induce three point loading into the beam. The following is a brief commentary on the design and fabrication of the test rig.

DESIGN & CONSTRUCTION The following equipment was available to the project team which allowed loading and measurement of the load placed on the beam: ton Lever Hoist 3 ton Lever Hoist 10 ton Load Cell 2 ton Round Slings 3 ton Round Slings Various Lifting Shackles Computer capable of connecting to the Load Cell.

Given the available testing equipment it was decided to design a triangular truss-like test rig out of structural timber and test the beam horizontally with the beam lying on its side (Strong axis parallel to the ground). This configuration allowed the beam to be loaded almost entirely through the test rig with only the self weight of the beam acting along the weak axis of the beam. Due to MGP10 being readily available at many hardware stores, it was decided that the test rig would be constructed of this material. The test rig load capacity was determined from the Timber Structures Design Standard (AS1720). The test rig incorporated three timber members, one tension member which ran parallel to the concrete beam, and two compression members which transfer load from the other end of the loading equipment to the supports of the beam. These two members, which were required to each support a compressive load slightly more than half the load being placed on the beam were also restrained against buckling with additional smaller timber members and were also during the second test sequence tied to the packing timbers below the concrete beam. Two


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 M16 bolts were used in each of the test rig connections. This gave a total of eight M16 bolts in the assembly. Supports were also fabricated out of MGP10 off cuts and were screwed to the end of the main compression members with self tapping wood screws. Additional restraints were added to the top and bottom of the supports to try to spread the loads across the supports more evenly and supports to spread the load being transferred into the compression members over a number of points of contact (Into the buckling restraints on the top of the compression members and into the tension compression member connection on the bottom of the compression member as well bottom as into the butt of the compression member where the support was originally screwed onto.

Figure 15: Completed Test Rig

DATA LOGGING Given that a load cell (and associated controller box with an RS232 serial output), was available for use in the test, it was decided to connect an old computer to the load cell controller box to capture and record the data from the load cell. An attempt was made to find software which was was capable of decoding and storing the data output from the load cell controller box, however no readily available software could be found. Hence a simple logging program was developed in VB.net to allow the data to be decoded and stored for later analysis. The decoded


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 program was capable of logging the time down to the millisecond that a measurement was received from the load cell controller box, the raw number received, the calculated Newton load on the beam and the calculated bending moment in the beam. The program was also capable of display the logged data on the computer screen.

BEAM TESTING

INTRODUCTION Testing of the beam was conducted sixteen days after the concrete was poured. Prior to testing two bolts were driven into the beam at the points of rotation on the axes of each support and a steel wire was tensioned between each to create a fixed reference line to allow measurement of deflection of the beam. The positions of the supports and the load were also marked on the beam using a permanent marker, as well as a number of marks below the reference wire. The positions of these marks were determined using a square placed on the beam and touching the reference wire to identify a position directly below the reference wire. The equipment and configuration used to place load into the beam was as follow: 1. A three ton round sling was doubled over the transfer plate at the apex of the test rig. Doubling over the round sling effectively doubles the load capacity of the sling to approximately six ton.

2. An 8.5 ton screw pin bow shackle was used to attach the round sling at 1 to the load cell at 3.

3. A ten ton load cell. The load cell was placed in this location to minimise the chance of damaging it should there be a failure in the test rig or loading equipment.

4. A three ton lever hoist was attached to the other end of the load cell at 3. This device was used to place load into the beam. The lever section of the lever hoist was placed on the load cell and the chain section extended to the round sling at 5.


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 5. A two ton round sling was doubled over a small piece of MGP10 which was used to place a point load across the face of the beam. Doubling over the round sling effectively doubles the load capacity of the sling to four ton. Additional three ton round slings were on hand and a six ton lever hoist was available should they be required to place additional load into the beam. These were not used initially.

TEST ONE Test one was conducted up to the cracking load of the beam. Load was placed into the beam gradually stopping at regular intervals to measure any deflection of the beam. Below is a detailed description of this test.

Test One Beam Loading18 16 Beam Load (kilonewtons) 14 12 10 8 6 4 2 0 0 60 120 180 240 300 360 420 480 540 600

Test Time (Seconds)Figure 16: Beam Load vs. Time (Test One)

TEST SEQUENCE AND OVERVIEW The slack in the loading equipment was taken out and the position of the beam relative to both the supports and the loading point was checked for centre. Once confirmed, load was gradually placed into the beam up to approximately 5kN and held relatively steady. The deflection of the beam was checked and found to be immeasurable. The load in the beam was then increased to approximately 10kN and the deflection was checked. Again the deflection DAMIAN ELLIS | PARAS GANDHI 24

INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 was found to be immeasurable. The sequence was repeated again at a load of 15kN, and again deflection was immeasurable. Upon attempting to increase the loading to 20kN the concrete of the beam experienced a brittle failure, reaching a maximum load of 16.965kN. Subsequent to failure, the beam continued to support a load of approximately 8.2kN, this load was as a of result of the residual tension in the loading equipment subsequent to the beam cracking and deflecting. After this event, prior to the load being let off to end the first test sequence the deflection of the beam wa measured at 4.38mm. was

RESULTS The beam did not experience any measurable deflection up until the point of cracking. Upon cracking, there was a significant deflection of the beam of 4.38mm and an audible cracking sound. The beam reached an absolute maximum load of 16.965kN before the concrete in the tensile region of the beam immediately failed in tension. It was noted that the crack appears to have been initiated by the presents of a reinforcing bar chair placed at the centre of the beam (See Figure 17).

Figure 17: Initial Crack in Beam (0kN Load on Beam)


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 Analysis of the detail view of the load cell output during the cracking event in Figure 18 shows that the failure appears to have occurred in two stages. The first being the failure of the concrete at the 374 second mark with the load sensed by the load dropping off over a period of approximately half a second. After the initial failure and deflection, the rubber appear to have taken some of the load, as evidenced by the slowing of the rate of load decrease starting at approximately the 374.5 second mark. This slowing continued for approximately 10 seconds until approximately the 384.5 second mark where there is a sudden, but slight reduction in load. This is likely due to a small amount of slippage of the rubber plies within the concrete. Subsequent to this the load in the beam levelled off to a relatively constant load. Upon removing the remaining load, it was noted that the beam had sustained a permanent deformation of 3.124mm. This is most likely due to a small amount of straightening of the rubber plies at the crack location, and potentially a small amount of slipping of the rubber plies within the concrete.

Cracking Event (Test One)17 16 15 Load (Kilonewtons) 14 13 12 11 10 9 8 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387

Test Time (Seconds)Figure 18: Cracking Event (Test One)

DISCUSSION The beam experienced a brittle failure at 16.965kN. To determine whether the beam performed as expected, the theoretical cracking load of the beam is calculated below:


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09Table 4: Theoretical Cracking Load for Rubber Beam (Ignoring Effect of Rubber)

Concrete Strength (fc) 32MPa Ft Ec Ag Ic Ih I Mc Lc

Concrete Unit Mass () 2500kg/m3

Section Width (bc & bh) 200mm & 100mm.

Section Depth (dc & dh) 270mm & 170mm

Beam Length (L) 1.7m = 3.394MPa = 30405.592MPa = 54000mm2

0.6

0.043

12 12 0.5 1000000 4

= 328050000mm4 = 40941667mm4 = 287108333mm4 = 7.218kNm = 16.984kN

The theoretical cracking load of the beam (calculated ignoring the presents of the rubber core), compares very well with the actual cracking load. However, one must also consider that the rubber core was more than likely contributing some strength to the beam prior to cracking. Therefore the beam is considered to have cracked at a load slightly lower than what would have been expected. This is likely due to the concrete not being vibrated to remove any air bubbles introduced into the concrete during mixing and placement. The crack appears to have been initiated by a plastic reinforcing bar chair placed at the centre of the beam to support the rubber core before and during the concrete pour (Figure 17). In hindsight, it would have been better to use two chairs instead of three and place them away from the centre of the beam, so at the point of greatest bending, there was only concrete and rubber to support the load. Due to the project team not being able to source an accurate device to continually measure deflection (Such as a linear position sensor and associated control systems), and not having time to fabricate one (weight and pulley systems and a lever based mechanical apparatus were considered), beam deflection was measured using a mark placed on the beam and the previously described wire tensioned across the beam using a set of digital vernier callipers. This proved difficult, as a square was also required to accurately determine the position of the wire relative to the mark on the beam. Ideally the deflection of the beam should have been DAMIAN ELLIS | PARAS GANDHI 27

INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 measured continuously, which would have allowed plotting of a load vs. deflection curve with much greater accuracy than was achieved in this test (See Figure 26).

TEST TWO Test two was conducted up until the beam deflected into the tension member of the test rig. Load was placed into the beam gradually stopping at regular intervals to measure any deflection of the beam. Below is a detailed description of this test.

Test Two Beam Loading26 24 22 20 18 16 14 12 10 8 6 4 2 0 0 1080 1200 1320 1440 1560 1680 1800 1920 120 240 360 480 600 720 840 960

Beam Load (Kilonewtons)

Test Time (Seconds)Figure 19: Beam Load vs. Time (Test Two)

TEST SEQUENCE AND OVERVIEW As for the first test cycle, the slack in the loading equipment was taken out and the position of the beam relative to the supports and the loading point was checked for centre. Load was subsequently gradually brought up in the beam to approximately the load shown on the load cell after the initial cracking of the beam (Approximately 8.5kN). At this point the crack width and beam deflection was measured and recorded. Following this the load in the beam was increased to 15kN, and measurements of crack width and deflection were again measured and recorded. Following this as the load was being increased to 20kN, it was noticed that the main compression members of the test rig were beginning to show signs of buckling. It was decided to add some additional restraints to these members in the form of metal straps wrapped DAMIAN ELLIS | PARAS GANDHI 28

INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 around the compression members and fixed to the timber packing blocks which the beam was sitting on (Keeping the beam elevated off the floor). Loading then continued to 20kN. Upon the load reaching 20kN an audible crack was heard and an associated moderate reduction in load was noticed. The crack was more muffled than the initial crack in the first test sequence and the reduction in load was less pronounced. Deflection and crack width were again measured. Load in the beam was then increased to 25kN and the crack width and deflection asured. measured again. During measurements the load in the beam reduced significantly to slightly more than 20kN. The load in the beam was again increased to 25kN, and the defl deflection and crack width measured again. Following this the test had to be aborted due to the beam deflecting far enough to touch the tension member of the test rig.

RESULTS

Figure 20: Beam Under Load During Second Test (13.695kN Beam Load)

Figure 19 shows much the same load curve as the test one curve up to 20kN. In both tests the load within the beam was gradually increased to a level, then while measurements were taken the load gradually decreased and settled to a lower load. Based on this occurring in the first test in much the same manner, it is most likely due to settling of the testing equipment and some settling within the test rig. Of note at the 1565 second mark as the beam load reached DAMIAN ELLIS | PARAS GANDHI 29

INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 20kN there was a reasonably significant drop in load, there was a significant deflection, and there was an audible crack, although more muffled than the initial concrete crack (See Figure 21). While nothing was noticed that explains the crack the video of this test clearly shows the deflection and some concrete rubble falling out from within the initial crack in the beam. Possible reasons for this are: 1. Some of the steel wires within the tyre plies snapped, allowing the tyre rubber to stretch further. 2. The rubber tyre block slipped within the concrete. 3. The concrete began to crush on the compression side of the beam.

Event At 20kN Load21 20 19 18 17 16 15 1520 1525 1530 1535 1540 1545 1550 1555 1560 1565 1570 1575 1580 1585 1590 1595 1600 Test Time (Seconds)Figure 21: Crack Event at 20kN

Following the crack event, load in the beam was increased to just under 25kN. It was noted that the load dropped away down to approximately 20.5kN quite quickly. The deflection at this point was 50mm. The load was again brought up to just under 25kN. Again the load dropped away quite quickly back to 20.5kN. The deflection at this point was 65mm. Given the significant deflection of the beam with no increase in load, it appears that the ultimate yield load of the beam is approximately 22kN. Loading the beam above this point appears to be causing the tyre plies to pull out of the concrete. Evidence of this can be seen by comparing Figure 23 and Figure 24, which both depict the inside of the initial crack after the first and second 25kN cycles.


Beam Load (Kilonewtons)

INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 At this point the beam had deflected far enough to touch the tension member of the test rig. Therefore the test had to be aborted. The load was released from the beam and the loading re equipment removed from the beam. Permanent deflection of the beam and the crack width was measured once more to determine the permanent deflection of the beam, which was found to be 28.3mm. This is quite a significant deflection which is almost certain to be due to nd pulling out of the rubber tyre plies from the concrete. After the loading equipment was removed it was noted that the concrete on the top compression side of the beam (top in test orientation), had experienced crushing failure at some point during the test. Upon further inspection it was noted that the beam had also experienced some deflection in the weak axis, evidently due to the self weight of the beam.

Figure 22: Evidence of Crushing Failure of the Beam (Compression Face) :



Figure 23: Rubber Tyres Inside Crack (21.215kN Beam Load, 1st 25kN load cycle) s

Figure 24 Rubber Tyres Inside Crack (20.849kN Beam Load, 2nd 25kN load cycle) 24: s



Figure 25: Beam deflection due to Self Weight

DISCUSSION As can be seen in Figure 26 upon reapplying the load supported by the beam after cracking, the deflection returned to approximately the same point. Beyond this, the rate of deflection per kilo-Newton appears to increase up to approximately 22kN where the beam experiences Newton significant deflection with no increase in load carrying capacity. This is likely to be the ultimate load capacity of this particular beam. It was noted that the ultimate failure mode of the beam appears to have been crushing of the concrete on the compression side of the beam as depicted in Figure 22. There was no evidence of damage to the rubber core of the beam, based . on observations of the rubber plies visible within the crack in the concrete. The likely reason for the concrete failing by crushing is due to the extreme deflection of the beam at ultimate load, which would have cause a very small area of concrete to carry the entire compressive loading within the beam. However, it must be noted that the deflection of the beam is partially due to the rubber plies pulling out of the concrete. As can be seen in Figure 26 the permanent deflection of the beam is significant at 28.3mm from a maximum deflection of 65mm. The permanent deflection therefore represents approximately 43.5% of the total deflect deflection. Hence, it can be concluded that if the rubber core can be better anchored into the concrete, the load capacity of the beam could increase significantly.


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 Following the test, the beam remained relatively intact, and was/is still capable of withstanding significant loading. Figure 22, Figure 28 and Figure 27 depict the damage sustained by the beam during testing.

Load vs Deflection (Both Tests)25

20 Load (Kilonewtons)

15

10

5

0 0 10 20 30 40 50 60 70

Deflection (Millimeters)Figure 26: Load vs Deflection (Both Tests)



Figure 27: Damage Sustained by Beam (Bottom (Floor) Face)

Figure 28: Damage Sustained by Beam (Tension Face)


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 COMPARISON TO EQUIVALENT SIZED BEAM TYPES

SOLID CONCRETE BEAM The theoretical capacity (To cracking) of a solid concrete beam of equivalent size to the test specimen is calculated below:Table 5: Capacity Calculations: Solid concrete beam

Concrete Strength (fc) 32MPa Ft Ec Ag Ic Mc Lc


Section Width (bc) 200mm.

Section Depth (dc) 270mm

Beam Length (L) 1.7m = 3.394MPa = 30405.592 = 54000mm2 = 328050000mm4 = 8.247kNm = 19.405kN

0.6

0.043 12

0.5 1000000 4

The cracking load of a solid concrete beam of the same dimensions as the test specimen is predicted to be approximately 2.5kN higher than the test specimen cracking load. However, following cracking an unreinforced beam it will immediately fail catastrophically, which is unacceptable in the vast majority of practical applications. A solid concrete beam would be approximately 28kg heavier than the theoretical rubber cored beam and 37kg heavier than the actual test specimen. A solid concrete beam of the same size as the test specimen would require an additional 0.029m3 of concrete which would add to the cost of the beam.

HOLLOW UNREINFORCED CONCRETE BEAM The theoretical capacity (To cracking) of a hollow unreinforced concrete beam of equivalent size to the test specimen is calculated below:


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09Table 6: Capacity Calculations, Hollow unreinforced concrete beam

Concrete Strength (fc) 32MPa Ft Ec Ag Ic Ih I Mc Lc


Section Width (bc & bh) 200mm & 100mm.

Section Depth (dc & dh) 270mm & 170mm

Beam Length (L) 1.7m = 3.394MPa = 30405.592 = 54000mm2 = 328050000mm4 = 40941667mm4 = 287108333mm4 = 7.218kNm = 16.984kN

0.6

0.043 12 12

0.5 1000000 4

The cracking load of a hollow concrete beam of the same dimensions as the test specimen is predicted to be approximately equal to the test specimens cracking load. However, following cracking an unreinforced beam will immediately fail catastrophically, which is unacceptable in the vast majority of practical applications. A hollow concrete beam would be approximately 44kg lighter than the theoretical rubber cored beam and 35kg lighter than the actual test specimen. A hollow concrete beam of the same size as the test specimen would utilise the same amount of concrete as the test specimen. However, forming the hollow in the centre would prove difficult, particularly in practical applications and would likely require some sort of filling material to create the void, such as expanded polystyrene which would add to the cost of the beam.

STEEL REINFORCED SOLID CONCRETE BEAM For this example, the steel reinforcing in the concrete beam is specified as: 3x N24 bars in the tension section of the beam, 2x N24 bars in the compression section of the beam, N12 ligatures at 100mm spacing (For mass calculations only)

Both the cracking load and the ultimate load of the beam have been calculated below:


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09Table 7: Capacity Calculations, Steel Reinforced Concrete Beam

Concrete Strength (fc) 32MPa Beam Length (L) 1.7m Ft Ec Ag n (n-1)Ast At dg

Concrete Unit Mass () 2500kg/m3 Cover to Tensile Reinforcement (c) 20+12+12 = 44mm 0.6

Section Width (b) 200mm Steel Area (Ast) 24 4 1357

Section Depth (d) 270mm Steel Modulus of Elasticity (Es) 200000MPa = 3.394MPa = 30405.592MPa = 54000mm2 = 6.578

.

0.043

1 2 12 1 2 10 1

= 7569.927mm2 = 61569.93mm2 = 146.188mm

IT

= 383029350mm4

Mc Lc Mu (fy = 500MPa) Lu 4 1

= 10.500kNm = 24.706kN

4

1.7

= 111.028kNm = 261.243kN

An example steel reinforced concrete beam of the same dimensions as the test specimen is predicted to crack at a load approximately 8kN higher than the test specimens cracking load. Following cracking a steel reinforced beam will deflect significantly before failing at a load much higher than the cracking load, in the case of this example beam at approximately 261kN. This is the desirable failure mode of a beam. The steel reinforced concrete beam would be approximately 55kg heavier than the theoretical rubber cored beam and 64kg heavier than the actual test specimen. A steel reinforced concrete beam of the same size as the test specimen would utilise 0.023m3 more concrete than the test specimen and would require approximately 42kg of reinforcing steel (Estimated requirement for a beam of this size), which will add significantly to the cost of the beam.


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 FUTURE TEST RECOMMENDATIONS

The results of this test indicate that further testing is warranted to determine the load carrying capacity of a beam of this type and to refine the design of the beam. As an aid to future researchers, the following recommendations are made as improvements to the technique used in the described test: 1. Press rubber plies together tightly and use wood screws on both sides to fasten them together. (This is how the rubber core was eventually fastened together in this test, however, other fastening systems were tried prior to this (described above), which did not fasten the plies together adequately).

2. Attach concrete anchors at regular intervals on both sides of the rubber core (Anchor screws screwed into the rubber or double nutted bolts fastened to the rubber).

3. Use either two chairs for supporting the rubber core at points 1/3 and 2/3 along the length of the rubber core, suspend the rubber core from the top of the formwork using tie wire, or support the rubber core with tie wire strung between two faces of the formwork at regular intervals along the rubber core.

4. Ensure the formwork is placed on a level surface when placing concrete.

5. Ensure the concrete is properly vibrated or otherwise to remove all air in the mixture.

6. Fabricate the testing rig from steel to minimise movement and deformation in the test rig or use an established testing facility.

7. Ensure the test rig allows for more significant deflections (Test rig used in this test allowed a maximum deflection of 65mm, which was considered adequate prior to testing).

8. Used round bars or rollers for supports and loading point to minimise or eliminate additional loading in the beam due to longitudinal and or non-point loading.


INNOVATIVE USE OF RECYCLED TYRES IN CIVIL ENGINEERING APPLICATIONS 13-Nov-09 9. Utilise loading equipment which is capable of more gradual movements (such as a hydraulic cylinder).

10. Utilise a linear position sensor or similar to measure deflection of the beam continuously during testing.

11. Use load measuring equipment which updates at a faster rate (Equipment used in this test updated at a rate of approximately six samples a second).

Figure 29: Beam Deflection at End of Test Two (Beam Load 20.760kN)

DAMIAN

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Innovative Use of Recycled Tyres in Civil Engineering Applic