Advantages of using recycled tire rubber in asphalt and differences in processesPLEASE CONSIDER THE BELOW POINTS AND APPLY IT (1) In main sections explain the past, the present and the future...

Contents
Abstract ...................................................................................................................................... 2
1. Topic of the Research ............................................................................................................ 3
2. Background of the Topic ....................................................................................................... 3
3. Research Objectives ............................................................................................................... 5
4. Various processes for creating RTR asphalt .......................................................................... 6
4.1 Dry Process On-Site ......................................................................................................... 6
4.2 Wet Process – On-site Blending ...................................................................................... 7
4.3 Wet Process - Terminal Blend ....................................................................................... 10
5. Various benefits of using recycled tire ru
ers for asphalt ................................................. 11
5.1 Low Temperature Performance ..................................................................................... 12
5.2 Retention of Wet Strength ............................................................................................. 14
5.3 Durability ....................................................................................................................... 16
5.4 Environmental Benefits ................................................................................................. 16
6. Case study ........................................................................................................................... 17
7. Conclusion ........................................................................................................................... 19
References ................................................................................................................................ 20
Abstract
The topic which has been discussed in this paper is advantages of using recycled tire
u
er in asphalt and differences in processes. Various advantages which have been
identified for the use of rercycled ru
er for asphalt are as following:
 Low Temperature Performance
 Retention of Wet Strength
 Durability
o Improved flexibility at the low temperature:
o Enhanced strength retention when wet:
o Resistance to creep or flow at very high temperatures;
o Greater resistance to oxidative hardening as a result of the ru
er antioxidants and
their presence.
 Environmental Benefits
There are different processes which are used for creating RTR asphalt and the three
most widely used amongst them are as following:
1. Dry Process On-Site
2. Wet Process On-Site
3. Wet at Process at Terminal
a. Particle and
. Non-particulate
All of these processes produce RTR asphalt with different performance as well as different
properties. It is important to be aware of these differences in view of the fact the same helps
in making choices regarding the type of process which will be the best fit for the required
application.
1. Topic of the Research
The topic which will be looked into this paper is
Advantages of using recycled tire ru
er in asphalt and differences in processes
2. Background of the Topic
Due to the ever increasing numbers of different motor vehicles on the roads of
developing as well as developed nations, enormous volume of used tyres are generated every
year. As per recent statistics, approximately 1.4 billion tyres are purchased every year
worldwide and hence similar number of tyres is classified as end of life tyres (ELTs)
eventually. Following figure provides a rate of recovery of the ELTs.
Figure 1. Evolution of ELTs recovery rates in major tyre markets
Also the number of ELTs for USA, Europe as well as Japan are going to rise in view
of the fact the increase projected number of vehicles as well as the worldwide traffic are
growing significantly. One of the most problematic sources of environmental waste is these
tyres as a result of their durability as well as the large volume produced. A number of
countries have been relying on the purpose of land filling for the disposal of the ELTs.
However the limited space as well as the potential for reuse has led to many countries
imposing a ban on this practice.
One of the major use in which the ELTs are being used is for recycling the tyre
u
ers and these Recycled tire ru
er (RTR) coming from the ELTs are being used
extensively for asphalt by the paving industry. This practice has been going on for multiple
decades starting from the 1960’s. RTR has been used for the asphalt in the following
manners:
 asphalt binder modifier and
 asphalt mixture additive in
o gap-graded and
o open-graded asphalt mixtures and surface treatments.
The cu
ent day use of RTR for the asphalt pavements started in the early 1960’s. A
surface patching material was developed by Charles McDonald, Materials Engineer for the
City of Phoenix, Arizona. McDonald developed a highly elastic RTR modified binder and
aggregate topping. During these initial days at the hot-mix plant field blending was done for
the asphalt ru
er and the same was immediately used as a result of the lack of intrinsic
stability of the product. These developments helped the early growth of the applications of
asphalt ru
er (AR), which included the following:
 surface treatments,
 interlayers, and
 AR open-graded friction courses (AR-OGFC).
In the year 1991 a United States federal law was proposed which led to significant
changes to the planning and policy of transportation for the entire nation. This act was termed
as Intermodal Surface Transportation Efficiency Act (ISTEA). This act called for all the
egions of the nation to use a pre defined amount of crumb ru
er from the recycled tires for
the development of asphalt surfacing. This led to widespread usage of the RTR for the asphalt
and there were various advantages which were identified slowly for the same.
In this paper, a discussion will be done with the purpose of looking into the various
enefits which can be drawn from the using of RTR in the asphalt as well as the various
processes which are used for the same.
3. Research Objectives
For any research to be completed effectively as well as efficiently, it is very important
that a set of research objectives are developed which help in ensuring that the research
process stays within the intended limit of the research.
For the purpose of this research 2 objectives have been identified and the same will be
used for the purpose of guiding the discussion on the same. Following are these research
objectives:
1. To identify as well as discuss the various processes which are implemented for
using RTR in asphalt
2. To understand various benefits which can be derived through using recycled tire
u
ers for asphalt
3. To discuss a case study that helps in creating better understanding regarding the
aforementioned factors
We will start the discussion with the topic of various processes which are implemented for
using RTR in asphalt.
4. Various processes for creating RTR asphalt
There are different processes which are used for creating RTR asphalt and the three
most widely used amongst them are as following:
1. Dry Process On-Site
2. Wet Process On-Site
3. Wet at Process at Terminal
a. Particle and
. Non-particulate
All of these processes produce RTR asphalt with different performance as well as
different properties. It is important to be aware of these differences in view of the fact the
same helps in making choices regarding the type of process which will be the best fit for the
equired application.
4.1 Dry Process On-Site
In the dry process the RTR which is used is considered to be an aggregate
eplacement in the mix and not just a binder additive. Asphalt ru
er developed by dry
process is the least commercially significant.
Figure 2. Feed system to add dry RTR into mixture production plant.
Similar to the process of reclaimed asphalt, dry RTR is added to the mixture
production plant. The ru
er which is used is usually the larger size particles between 4.75 to
1.00 mm or 4 to 18 mesh. Usually the cryogenic ru
er is used as far as this process is
concerned. Gap-graded aggregate mixtures are necessary for providing space for the particles
of the ru
er. In the above figure it is shown the way RTR is being added into the RAP collar
on the mixture production plant drum....