Innovative Use of Recycled Tyres in Civil Engineering Applic
Innovative Use of Recycled Tyres in Civil Engineering Applic
Innovative Use of Recycled Tyres in Civil Engineering Applic
RECYCLED TYRES IN
CIVIL ENGINEERING
APPLICATIONS
Thesis Report
AUTHORS
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
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.
ACKNOWLEDGEMENTS
IN PARTICULAR WE WOULD
WOU LIKE TO THANK DR. KAMIRAN ABDOUKA OF SWINBURNE
S
UNIVERSITY OF TECHNOLOGY
TECHNO WHOM GUIDED US AND SUPPORTED US THROUGHOUT
THR THE
DEVELOPMENT OF THIS PROJECT.
IN ADDITION, WE WOULD
OULD ALSO LIKE TO THE
THE THANK THE FOLLOWING
FOLLOWIN ORGANISATIONS
WHO KINDLY PROVIDED MATERIAL, TOOLS, EQUIPMENT,
IPMENT, AND GENERAL ASSISTANCE
WHICH WERE ESSENTIAL TO THE TESTING PERFORMED
RMED DURING THE COARSE
COAR OF THE
PROJECT.
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 they’re 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.
CONTENTS
Authors........................................................................................................................................... ii
Disclaimer...................................................................................................................................... iii
Acknowledgements....................................................................................................................... iv
Abstract .......................................................................................................................................... v
Introduction ................................................................................................................................... 1
Cryogenic Grinding.................................................................................................................... 2
Microwave Technique............................................................................................................... 5
Properties................................................................................................................................ 10
Application .............................................................................................................................. 10
Rlayground construction......................................................................................................... 11
Combustion: ............................................................................................................................ 14
Pyrolysis .................................................................................................................................. 14
Conculsion .................................................................................................................................... 15
Formwork ............................................................................................................................ 18
Data Logging........................................................................................................................ 22
Beam Testing........................................................................................................................... 23
Introduction ........................................................................................................................ 23
Australian codes for road safety barriers system (AS/nzs3845, 1999) ........................................ 44
Discussion..................................................................................................................................... 56
Conclusion .................................................................................................................................... 57
References ................................................................................................................................... 58
LIST OF FIGURES
Figure 6: Tread Ring Load vs Displacement (Turer & Gölalış 2008) .............................................. 6
Figure 9: Tyres were dumped in 1970s in an attempt to establish an artificial reef. ................. 11
Figure 11: Tread Section of Rubber Tyre as used in the Conceptual Beam. ............................... 17
Figure 20: Beam Under Load During Second Test (13.695kN Beam Load) ................................. 29
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 29: Beam Deflection at End of Test Two (Beam Load 20.760kN) .................................... 40
Figure 33 Recommended test summary sheet for crash test results as per NCHRP report 350
report, on page number 58 and onwards. .................................................................................. 46
Figure 35 Plan section of with reinforced car tyre strips showing internal tensions and
compression areas. (Charleson 2005)......................................................................................... 53
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
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 4: Theoretical Cracking Load for Rubber Beam (Ignoring Effect of Rubber)..................... 27
Table 9 Pricing Comparison for RCC Beam & Rubber Concrete Beam with considering the
dimension 0.27x0.20x1.80 .......................................................................................................... 42
Table 12: Formulae Used for Calculating Railway Sleeper Bending Moments ........................... 47
INTRODUCTION
The overall aim of this research project is to determine the feasibility of utilising generally
unprocessed waste tyres
tyres in novel ways in civil engineering applications. In order to achieve
this, it is necessary
ary to first analyse previously published knowledge relating to the research
topic in the following area:
The following literature review will summarise key research papers and other information
sources relating to the above three sub-topics,
sub which will allow for more detailed analysis of
the feasibility of potential
potentia civil engineering applications for waste tyres
tyre identified during the
course of this research project.
According to Williams
(2007) the importance of
rubber (tyre)) recycling was
realised as far back as the
initial discovery of
vulcanisation in 1839
separately by Charles
Goodyear and Thomas
Hancock.. However, a viable
recycling technique wasn’t
described until 1899 by
Arthur Marks,, who
Figure 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 & Gölalış (2008). The authors state that approximately half of the tyres
produced until the 1960’s 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 & Gölalış (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 & Gölalış’s
(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 590µm and 149µm. Eldin & Senouci’s (1993) and Pilakoutas’s et al. (2004)
descriptions of the process compare in principal with Klingensmith’s (1991) description of the
process. Pilakoutas et al. (2004) adds that the rubber is pre-cooled using nitrogen gas at a
temperature of approximately -120°C (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
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
ent than ambient temperature grinding.
Figure 2:: 420um Rubber Powder (Jingdong Rubber Co., Ltd. Figure 3:: 0.6mm Ambient Ground Rubber (reRubber 2009)
2009)
Ambient temperature
mperature grinding/shredding produces courser rubber particles then cryogenic
grinding. The manner in which the rubber particles are produced also differs somewhat
between ambient temperature and cryogenic grinding. Jang et al. (1998) contrasts the
t modes
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
contrast to cryogenic grinding,
ambient temperature grinding produces particle sizes in the order of 0.6mm to 2mm.
Klingensmith (1991) & et al. (1998),
(1998) Jang et al. (1998), and Weber et al. (2008) all generally
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
ased in recent years ‘as it is more economical to transport shredded tyres
rather than whole tyres’
tyre (Pilakoutas et al. 2004). Ambient temperature grinding is also
identified as potentially quite expensive by Pilakoutas et al. (2004). However,
H in contrast to
this Eldin & Senouci (1993) state that ambient temperature grinding is significantly cheaper
than cryogenic grinding.
grinding Klingensmith et al. (1998) also agrees that ambient temperature
grinding is a relatively inexpensive technique. Given the embodied energy
ener in the liquid
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.
MICROWAVE TECHNIQUE
The microwave technique decomposes rubber in much the same mode as the traditional
pyrolysis technique described above.
above Adhikari & Maiti (2000) describe the technique as using
‘a controlled dose of microwave energy at specified frequency and energy level in an amount
sufficient
fficient to cleave carbon-carbon
carbon carbon bonds’. Whereas similarly Pilakoutas et al. (2004) describes
the process as using ‘optimised microwave power at the molecular level to thermally
decompose tyres’.
s’. Both papers conclude that the microwave technique is more energy
en
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
defeat the purpose.
ULTRASONIC TECHNIQUE
Klingensmith & Baranwal (1998) describe the ultrasonic technique as ‘devulcanization’. The
technique involves exposing crumb rubber from waste tyress to high intensity ultrasonic
vibrations which are absorbed by the rubber
rubber which is theorised to fracture the sulphur-sulphur
sulphur
bonds which produces a rubber which can be reprocessed back into virgin rubber and re-cured
re
(Klingensmith & Baranwal 1998). Further detail on this technique is described in a paper by
Adikari & Maiti (2000).
(2000). In contrast to Klingensmith & Baranwal (1998) the authors state that
MECHANICAL PROPERTIES
PROPERTIE OF TYRES
Turer & Gölalış (2008) surmise that the following factors will affect the tensile capacity of a
tread ring:
• he amount, orientation and tensile capacity of the steel strands within the tread ring.
The ring
• The cross-sectional
sectional area of the tread ring.
• 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.
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.
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 &
Senouci’s (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)).
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.
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”)
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 Feature
Black Opaque
Liquid State Low Freezing point
Low Density Specific Gravity 1.12 to 1.15
Water Resistant Non wicking
Low Thermal Conductivity Thermal Barrier
Low Electrical conductivity Insulator
Absorption High absorption of most organic liquids
Rheology Elastic, compliant, and resilient
Enthalpy High heat of combustion and low ash content
Organic Non biodegradable
APPLICATION
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 (TDM’S) and include a higher portion, crumb rubber materials
(CRM’S) 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
energy. Further application of recycled tyre will be divided in two sections as processed and
unprocessed recycle use of tyre.
USE OF UN-PROCESSED
PROCESSED TYRES IN CIVIL ENGINEERING
NG APPLICATION
REEFS
EEFS AND BREAKWATER
Break-Water:
Water: One of the applications of the scrap tyre is also to construct a break-water.
break
Discarded tyress used for
for constructing breakwater are filled with foam and which displaces
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
LAYGROUND CONSTRUCTION
CONSTRUCTI
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 tyres
tyre are used every year
in USA for the construction from discarded tyres. This application
on for using of recycled tyres is
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.
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.
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:
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 by
b a magnetic field
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
they are contaminated by their original
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
tyress in capable for 1000 MPa to 1200 MPa
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.
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.
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.
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:
Tyress were cut around both edges of the tread ring to separate the tyre side walls and beads
from the tread ring. An electric jigsaw with a hacksaw blade attachment was used to cut the
tyres.
s. The remaining tread rings were then cut across the tread using the same jigsaw. This
created a rubber tread strip of approximately 1700x170x10mm.
1700x170x10mm. Eight tyres were cut in this
manner to create eight plies. It was noted during cutting that the Bridgestone and Michelin
tyress were slightly harder to cut than the Simex and (No Name) tyres.
tyre This likely indicates a
greater number and/or stronger steel threads used in the name-brand
brand tyres over the non-
name-brand tyres.
s. Every different tyre was having different level of boldness. Some the
specimen tyress were completely bold and edges and were not having any texture left.
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
tensioning of the wire subsequent to the wire
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:
To try and reduce the deformation and better bond the plies together, chipboard screws were
driven into the pliess at even spacing at the top and bottom of both sides of the beam. In key
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 wire,
wi as was used to tie the tyre plies of the rubber core together. Wood
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
nt the concrete from bonding to the formwork.
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.
concrete. As the pour location was within an operating
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 member’s
house. Upon delivering the beam to the testing location, the formwork was removed. It was
noted
oted that the concrete did not appear to have been vibrated nor did it appear to have been
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:
The likely reasons for the disparity between the actual and calculated mass are as follows:
The mass of the rubber cored beam is significantly less than that of an equivalent solid
concrete
te beam with a mass saving of approximately 37kg. This equates to a mass saving over
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 saving
sav of
approximately 64kg. This equates to a mass saving over an equivalent sized steel reinforced
concrete beam of approximately 24%.
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.
The following equipment was available to the project team which allowed loading and
measurement of the load placed on the beam:
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
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
supports more evenly and
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
bottom of the compression member as well
as into the butt of the compression member where the support was originally screwed onto.
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
was made to find software which
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
decoded and stored for later analysis. The
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.
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.
16
14
Beam Load (kilonewtons)
12
10
0
0 60 120 180 240 300 360 420 480 540 600
Test Time (Seconds)
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
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
of approximately 8.2kN, this load was as a
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 was
wa measured at 4.38mm.
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).
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.
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
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:
Table 4: Theoretical Cracking Load for Rubber Beam (Ignoring Effect of Rubber)
Concrete Concrete Unit
Section Width Section Depth Beam Length
Strength Mass
(bc & bh) (dc & dh) (L)
(f’c) (ρ)
200mm & 270mm &
32MPa 2500kg/m3 1.7m
100mm 170mm
F’t 0.6 = 3.394MPa
Ec
. 0.043 = 30405.592MPa
Ag = 54000mm2
Ic = 328050000mm4
12
Ih = 40941667mm4
12
I = 287108333mm4
0.5
Mc = 7.218kNm
1000000
4
Lc = 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
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.
20
18
16
14
12
10
8
6
4
2
0
0
120
240
360
480
600
720
840
960
1080
1200
1320
1440
1560
1680
1800
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
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.
asured. Load in the beam was then increased to 25kN and the crack width and deflection
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 deflection
defl 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
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.
20
Beam Load (Kilonewtons)
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)
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.
At this point the beam had deflected far enough to touch the tension member of the test rig.
Therefore
re the test had to be aborted. The load was released from the beam and the loading
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
nd to be 28.3mm. This is quite a significant deflection which is almost certain to be due to
‘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 23: Rubber Tyress Inside Crack (21.215kN Beam Load, 1st 25kN load cycle)
Figure 24:
24 Rubber Tyress Inside Crack (20.849kN Beam Load, 2nd 25kN load cycle)
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
Newton appears to increase up to approximately 22kN where the beam experiences
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 deflection.
deflect
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.
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.
20
Load (Kilonewtons)
15
10
0
0 10 20 30 40 50 60 70
Deflection (Millimeters)
The theoretical capacity (To cracking) of a solid concrete beam of equivalent size to the test
specimen is calculated below:
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.
The theoretical capacity (To cracking) of a hollow unreinforced concrete beam of equivalent
size to the test specimen is calculated below:
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.
For this example, the steel reinforcing in the concrete beam is specified as:
Both the cracking load and the ultimate load of the beam have been calculated below:
Ec
. 0.043 = 30405.592MPa
Ag = 54000mm2
n = 6.578
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.
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.
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.
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)
Scrap rubber is the famous raw material in the market which is available without any cost. On
top of it rubber is a kind of material which bring money along with because any one gets paid
to use scrap rubber, if the use is environmental friendly.
By reviewing the current market out team got the current concrete price as follows:
Price/m3
Concrete Grade
M20 173.50
M25 178.50
M32 187.50
M40 195.50
For most of the diameter reinforcement bar the current market price is approximately 2800.00
AUD per metric tonne.
Courtesy: ONE STEEL Reinforcing
Steel used: 0.05 metric tonne steel would have used @ 2800AUD/tonne=0.05*2800= 140 AUD
For the reinforced concrete beam of 0.27x0.20x1.80 size, material cost is estimated
approximately
Rubber is a free material which is widely available throughout the market. Usually when we
buy scrap car tyres from market we get around 3 AUD per tyre. But we are not taking that
amount in consideration as that amount will be spend on transportation of tyres to the site.
Practically the total cost of rubber tyre beam cost is only concrete.
Table 9 Pricing Comparison for RCC Beam & Rubber Concrete Beam with considering the dimension 0.27x0.20x1.80
For the other cost of like formwork, labour, overheads and etc. are assumed to be same for
the both the types of beams. For the quantity used in the above table refer Table 3 on page
20.
CURRENT
URRENT ROAD SAFETY BARRIERS
B IN AUSTRALIA:
1. Rope Barrier
2. Thribeam type Barrier
3. Crash Cushion Barriers
AUSTRALIAN
USTRALIAN CODES FOR ROAD SAFETY BARRIERS SYSTEM (AS/NZS3845, 1999)
As per the clause 1.7 on page number 13, standards allows the use of material on field which
are not mentioned in the codes with the condition of agreement of both contractor and
manufacturer. Further the material should satisfy the primary requirements of the safety and
should pass the test standards according to NCHRP 350 report.
In clause 2.3.2 on page number 15, says that road safety barrier shall
shall be operating with their
normal efficiency between temperature range from -20⁰C to +50⁰C.
As per the table 2.3.19 on page number 20 the road safety barrier has to pass the following
test level as per the table below:
Further for the finishing of the material the clause 2.4.5 forces the product to have a surface
finish that minimizes the friction between the product and an impacting vehicle. As in our
product the finishing surface is of concrete so the friction is proven to be good between
impacting vehicle and concrete surface. Further in the same clause it is also mentioned that
the surface should not affected by detergents and similar agents that are used to clean the
external surface.
The material condition mentioned above which are requirements of the Australian standards
for the road safety barriers from AZ/NZS 3845 satisfy the product which is designed and
which is also experimented. Table number 3 mentioned above for the test level of the final
product, but it is not possible to conduct those tests at this point of time as further research
and testing equipments were not available.
It is mentioned in the clause 5.2 on page number 49 of AS/NZS 3845 that certification of the
new system will be under NCHRP (National Cooperative Highway Research Program) 350
report. To compile with some specific condition and requirements of Australia and New
Zealand, there are some modification done is NCHRP 350 report with are mentioned in tabular
form on and towards page 49 of AZ/NZS 3845 which falls under clause 5.3
Figure 33 Recommended test summary sheet for crash test results as per NCHRP report 350 report, on page number 58 and
onwards.
During development of this report, a potential use for a beam of similar construction to the
test beam was identified in the rail industry as railway sleepers. The following is a brief
overview of the feasibility of such a use.
The formulae used to calculate sleeper moments in this section are as follows (All for Broad
Gauge):
Table 12: Formulae Used for Calculating Railway Sleeper Bending Moments
6! 7#
Positive Bending
45
AS1085.14 &
8
Moment at Rail Seat
AS1085.17
(kNm)
Positive Bending
95 0.056! 7#
AS1085.14 &
Moment at Centre
AS1085.17
(kNm)
Negative Bending ;!27 #
9: 0.5 167 );7! 7#+ 2
AS1085.14 &
8
Moment at Centre
AS1085.17
(kNm)
46
;
AS1085.14 &
3 27
W
AS1085.17
Where:
• R = Design rail seat load (kN) – Taken as 50% of typically adopted single axle load
(AS1085.14, Fig. 4.1) on Australian main lines of 25t (AS1085.14, Clause E2.1.1),
therefore 122.6kN.
• L = Length of sleeper (m) – For Victorian broad gauge standard taken as 2.6m.
• g = Distance between rail centres (m) – Taken as 1.675m (Based on estimated typical
track width of 75mm and broad gauge width of 1600mm).
Using the above formulae and variables, the following moments were calculated for a typical
example sleeper. Sleeper spacing was taken as 600mm which is an average spacing for the
various types of sleepers currently in use:
• MR+ = 14.176kNm
• MC+ = 5.670kNm
• MC- = 13.431kNm
These moments are used below to determine the stresses in various sleeper types.
There are currently three major types of sleepers in use. They are timber sleepers which have
been the typical sleeper type used in railway construction since railways began, concrete
sleepers, which are becoming more and more common today, and steel sleepers, which are
used in some situations.
TIMBER SLEEPERS
Timber sleepers have been in use since the beginnings of true railways. They are generally
made from a strong hardwood, and generally treated to increase durability. In Victoria,
standard sleeper specifications (Broad Gauge) are as follows:
Maximum stress in this timber beam example is approximately half of the characteristic
bending stress for the type of timbers typically used in railway sleepers.
• Must be replaced every 20-25 years due to degradation and rotting of the timber,
• During temperature extremes can cause tracks to warp,
• Can be expensive, depending on availability of timber.
Concrete sleepers have been in use since the early 1900s and have been becoming increasingly
common. Typically in Australia concrete sleepers are prestressed. In Victoria, standard sleeper
specifications (Broad Gauge) are as follows (Assumed rectangular sleeper shape and ignoring
prestressing effects):
Maximum stress in this concrete beam example is slightly higher than the cracking stress of the
sleeper. However, one must take into account the prestressing load within the beam. Hence, it
is highly likely that the prestressing force will effectively cancel out any tensile stresses in the
concrete of the sleeper, or at worst minimise the tensile stresses. Unfortunately little
information could be found regarding the typical prestressing force applied to concrete
sleepers, which prevents a full analysis of the loading capacity of a prestressed concrete
sleeper.
STEEL SLEEPERS
Steel sleepers have been in use since the 1950s. However, the majority of steel sleepers in use
today have been installed during the past 20 years. In Victoria, standard sleeper specifications
(Broad Gauge) are as follows:
Maximum stress in this steel beam example is slightly higher than the yield stress of the
sleeper. However, the calculations do not take into account the effect of ballast packed inside
the hollow of the sleeper, which will reduce the maximum bending moment experienced by
the sleeper.
As an example to compare the potential suitability of a rubber tyre core concrete sleeper, the
following properties are proposed:
While the maximum stress is higher than the cracking stress of this example sleeper, it might
be possible to use the tyre plies of the rubber core of the sleeper as prestressing tendons. If it
proves possible to reliably prestress the rubber core to, for example, the maximum tensile
stress the concrete of the sleeper must withstand, it will effectively cancel out the tensile
stress experienced by the concrete, and may lead to a concrete sleeper with a prestressed
recycled tyre rubber core to become a viable alternative to the sleeper types described above.
• Brittle, will shatter due to impacts, however, the prestressed rubber core may act
absorb the impact better than a normal prestressed concrete sleeper, and act to hold
the damaged sleeper together, and allow continued limited use of the railway
supported by the sleeper until replacement can be scheduled.
• Requires establishment of a factory or other similar facility to manufacture,
• May prove difficult to prestress rubber core adequately and/or reliably.
A.W. Charleson & M.A. French of School of Architecture of Victoria University of Wellington in
New Zealand experimented for improving seismic safety of abode construction with use of
scrap car-tyre strips in 2005. The basic concept of this innovative idea was to use spiral cut
strips from the treads of used tyres to provide tension resistance for the single storey
construction.
The tyres were separated into three components and five meter long continuous strips was
prepared out of the treads. The tyre beads were also used to provide confinement to the
adobe elements in specific locations and to reinforce certain type of connections. The tyre
strips and beads were made responsible to provide tension strength necessary to resist all
earthquake loads and other loads acting on building.
Figure 35 Plan section of with reinforced car tyre strips showing internal tensions and compression areas. (Charleson 2005)
This idea was been proven by the evidence of the experimental result. The process of the
experiment is as follows:
Firstly strain
strain-rate test was
performed on four different
brands and but one of the brand
was having a slippery interior
surface.
It was also decided that there are
three options for joining tyre
strips to make one 5 meter long
strip and they were vulcanizing,
nailing and bolts. Nailing was the
preferred option but in first test
Further load case was like four Figure 37 Experiment trial arrangement for applying
applyi load on specimen
without tyres. (Charleson 2005)
point loads of bucket filled sand
bags. The load from those sand bags were transferred to timber load-spreaders
load on the
rear face of the wall by a simple pulley and steel cable arrangements. This model was
completely unreinforced
unreinf i.e. no tyress were used in this model. The wall collapsed at 70
kg load.
Further one more model was prepared similar to first one but in this model the tyre
strips were reinforced at the half wall height as shown in Figure 38 Tyres wrapped at
the half wall height at corner.
corner. This model was loaded in different load conditions like
firstly loaded in stronger direction than replacing with load on opposite direction. The
wall collapsed suddenly at load of 185 kg.
FUTURE
UTURE OF USAGE OF CAR-TYRE
CA RUBBER IN EARTHQUAKE CONSTRUCION
There were also some recommendations by the research team for further development:
• Free-standing piers needed to be tested as they were not playing any role in above
experiment.
• Experiment the face-loading condition for preventing premature failure from strap
eccentricity.
• Further research should be carried out on connections between foundations, roof
structures and tyre strips.
• A full tyre reinforced house needs to be tested on a full-dynamic shaking table.
DISCUSSION
In the current trend there are various methods by which tyres are getting recycled and used in
civil engineering application but they use tremendous amount of energy so they are worth
using as a recycled material. The main idea behind this proposal was to the use the scrap tyres
without use of energy. Previously in this report the overall proposal of Recycled use of tyre was
mentioned and then after our team came up with some results by conducting experiment. As
this proposal was been introduced first time, our team did not have many resources to
compare the results of the experiments. Further we also had a quick look on the Australian
Standards and there requirements for this proposal. The test recommendations mentioned in
National Co-operative Highway Research Program were not completed by our team as to
conduct test at this point of time was not possible due to lack of laboratory resources and
further research.
Further there were many ideas to use scrap tyre in civil engineering application but at this
stage they are still concepts. This area needs to be researched more deeply. There were some
ideas which our team came up with.
Recycled Tyres-Concrete Column which can be used as retaining wall or even those can be
used as piles.
Rubber has very good sound absorption properties. In the current market trends shredded tyre
rubber is used as aggregates. Further by making the concrete walls out of rubber tyre strips,
they
CONCLUSION
In the current trend there are various methods by which tyres are getting recycled and used in
civil engineering application as we discussed at the start of this report but they use
tremendous amount of energy so they are not worth using as a recycled material. The main
idea behind this proposal was to the use the scrap tyres without or with minimum amount of
energy. Previously in this report the overall proposal of Recycled use of tyre was mentioned
and then after our team came up with some results by conducting an experiment. As this
proposal was been introduced first time, our team did not have many resources to compare
the results of the experiment. Further we also had a look on the Australian Standards and their
requirements for this proposal. The test recommendations mentioned in National Co-
operative Highway Research Program were not completed by our team as to conduct test at
this point of time was not possible due to lack of laboratory resources and finances.
Further there were many ideas to use scrap tyres in civil engineering applications but at this
stage they are still concepts. These areas need to be researched more deeply. There were
some ideas which our team came up with:
• Concrete Columns formed from recycled tyres which can be used as retaining wall or
as piles.
• Rubber has very good sound absorption properties. In the current market trends
shredded tyre rubber is used as aggregates for concrete. It may be possible to make
the concrete walls out of waste rubber tyre strips, which will lead to a reduction of
energy input and cost of manufacture and will still maintain the sound absorption
properties of current rubber aggregate concrete walls.
• Scrap tyre rubber as a solo material has high chemical strength and will not be affected
by soil condition. By conducting further research on underground rubber sheathed
concrete structures can be used in areas with adverse soil conditions. By doing this the
life of concrete structures can be extended by protecting the concrete and steel of the
structure by encasing in waste rubber tyres.
Our team recommends conducting further research by modelling and experimenting on usage
of scrap tyre strips concrete beam in road crash barrier, any non-loading bearing structure,
earthquake construction and railway sleepers.
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APPENDIX DVD