This presentation describes about how is a flexible pavement is constructed using Plastic Wastes

1. USE OF PLASTIC WASTE
IN CONSTRUCTION OF
FLEXIBLE PAVEMENTS
Group Participants:-
Raghvendra Bajpai
Osama Bin Sami
Pawan Kr. Srivastav
Pramod Kr. Yadav

2. WHAT IS A PAVEMENT?
 A road surface or pavement is the durable surface material
laid down on an area intended to sustain vehicular or foot traffic,
such as a road or walkway. In the past, gravel road surfaces,
cobblestone and granite setts were extensively used, but these
surfaces have mostly been replaced by asphalt or concrete laid
on a compacted base course. Road surfaces are frequently
marked to guide traffic. Today, permeable paving methods are
beginning to be used for low-impact roadways and walkways.
Pavements are crucial to countries such as US and Canada, which
heavily depend on road transportation. Therefore, research
projects such as Long-Term Pavement Performance are launched
to optimize the life-cycle of different road surfaces.

3. TYPES OF PAVEMENTS
 Rigid Pavements:
 A rigid pavement is constructed from cement concrete or
reinforced concrete slabs. Grouted concrete roads are in the
category of semi-rigid pavements.
 The design of rigid pavement is based on providing a
structural cement concrete slab of sufficient strength to
resists the loads from traffic. The rigid pavement has rigidity
and high modulus of elasticity to distribute the load over a
relatively wide area of soil.

4.  Minor variations in subgrade strength have little influence
on the structural capacity of a rigid pavement. In the design
of a rigid pavement, the flexural strength of concrete is the
major factor and not the strength of subgrade. Due to this
property of pavement, when the subgrade deflects beneath
the rigid pavement, the concrete slab is able to bridge over
the localized failures and areas of inadequate support from
subgrade because of slab action.
 Flexible Pavements:
 Flexible pavement can be defined as the one consisting of
a mixture of asphaltic or bituminous material and aggregates
placed on a bed of compacted granular material of
appropriate quality in layers over the subgrade. Water bound
macadam roads and stabilized soil roads with or without
asphaltic toppings are examples of flexible pavements.
 The design of flexible pavement is based on the principle
that for a load of any magnitude, the intensity of a load
diminishes as the load is transmitted downwards from the
surface by virtue of spreading over an increasingly larger
area, by carrying it deep enough into the ground through
successive layers of granular material.

5. CONSTRUCTION DETAILS
1. Subbase course construction
 A subbase course is a layer designed of carefully selected
materials that is located between the subgrade and base
course of the pavement. The subbase thickness is generally in
the range of 4 to 16 inches, and it is designed to withstand
the required structural capacity of the pavement section.
2. Base course construction
 The base course is the region of the pavement section that
is located directly under the surface course. If there is a
subbase course, the base course is constructed directly about
this layer. Otherwise, it is built directly on top of the
subgrade. Typical base course thickness ranges from 4 to 6
inches and is governed by underlying layer properties.

6. 3. Surface course construction
 There are two most commonly used types of
pavement surfaces used in highway construction: hot-mix
asphalt and Portland cement concrete. These pavement
surface courses provide a smooth and safe riding surface,
while simultaneously transferring the heavy traffic loads
through the various base courses and into the underlying
subgrade soils.

7. DESIRABLE PROPERTIES
 Strength
 The aggregates used in top layers are subjected to (i) Stress
action due to traffic wheel load, (ii) Wear and tear, (iii) crushing.
For a high-quality pavement, the aggregates should possess
high resistance to crushing, and to withstand the stresses due
to traffic wheel load.
 Hardness
 The aggregates used in the surface course are subjected to
constant rubbing or abrasion due to moving traffic. The
aggregates should be hard enough to resist the abrasive action
caused by the movements of traffic. The abrasive action is
severe when steel tyre vehicles moves over the aggregates
exposed at the top surface.

8.  • Toughness
 Resistance of the aggregates to impact is termed as
toughness. Aggregates used in the pavement should be
able to resist the effect caused by the jumping of the steel
tyred wheels from one particle to another at different
levels causes severe impact on the aggregates.
 • Shape of aggregates
 Aggregates which happen to fall in a particular size range
may have rounded, cubical, angular, flaky or elongated
particles. It is evident that the flaky and elongated
particles will have less strength and durability when
compared with cubical, angular or rounded particles of the
same aggregate. Hence too flaky and too much elongated
aggregates should be avoided as far as possible.
 • Adhesion with bitumen
 The aggregates used in bituminous pavements should have
less affinity with water when compared with bituminous
materials, otherwise the bituminous coating on the
aggregate will be stripped off in presence of water.

9.  Durability
 The property of aggregates to withstand adverse action of
weather is called soundness. The aggregates are subjected to
the physical and chemical action of rain and bottom water,
impurities there-in and that of atmosphere, hence it is
desirable that the road aggregates used in the construction
should be sound enough to withstand the weathering action
 Freedom from deleterious particles
 Specifications for aggregates used in bituminous mixes
usually require the aggregates to be clean, tough and durable
in nature and free from excess amount of flat or elongated
pieces, dust, clay balls and other objectionable material.
Similarly aggregates used in Portland cement concrete mixes
must be clean and free from deleterious substances such as
clay lumps, chert, silt and other organic impurities.

10. PLASTIC ROADS
 Plastic Roads
 Plastic roads are roads made either entirely of plastic or
of composites of plastic with other materials. Plastic roads
are different from standard roads in the respect that standard
roads are made from asphalt concrete, which consists of
mineral aggregates and asphalt. Currently, there are no
records of regular roads made purely of plastic. Plastic
composite roads, however, have existed and demonstrate
characteristics superior to regular asphalt concrete roads;
specifically, they show better wear resistance. The
implementation of plastics in roads also opens a new option
for recycling post-consumer plastics.

11.  Construction
 Since plastic roads are a relatively new idea, construction processes
may vary. In Jamshedpur, India, roads are created from a mix of
plastic and bitumen. These roads are made from recycled plastics,
and the first step in constructing them is to collect and manage the
plastic material. The plastics involved in building these roads consists
mainly of common post-consumer products such as product
packaging. Some of the most common plastics used in packaging
are polyethylene terephthalate (PET or PETE), polyvinyl chloride
(PVC), polypropylene (PP), and high and low-density polyethylene
(HDPE and LDPE). These materials are first sorted from plastic waste.
After sorting, the material is cleaned, dried, and shredded. The
shredded plastic is mixed and melted at around 170°C. Hot bitumen
is then added and mixed with the melted plastic. After mixing the
mixture is laid as one would with regular asphalt concrete.

12.  So far, no large scale, systematic approach has been
employed to build roads entirely of plastics. The
plastic composite roads in Jamshedpur is not an ideal
method, since the plastic is not exploited for all of its
properties, which allow it to be formed into complex
structure. An innovative concept proposed by a Dutch
company, Volker Wessels, aims to create roads
entirely of recycled plastic. Building roads entirely
from plastic opens new possibilities in construction.
Construction can be significantly more efficient, since
roads can be created as individual pieces, which can
be switched out in case of damages. This is different
from traditional ways of road repair, which requires
long time spent on site shaping asphalt to the desired
shape. However, as of November, 2015 Volker
Wessels has yet to release much detail on its
proposed model.

13. AGGREGATE TESTS
 Crushing test
 One of the model in which pavement material can fail is by crushing under
compressive stress. A test is standardized by IS:2386 part-IV and used to
determine the crushing strength of aggregates. The aggregate crushing value
provides a relative measure of resistance to crushing under gradually applied
crushing load. The test consists of subjecting the specimen of aggregate in
standard mould to a compression test under standard load conditions (Figure 1).
Dry aggregates passing through 12.5 mm sieves and retained 10 mm sieves are
filled in a cylindrical measure of 11.5 mm diameter and 18 cm height in three
layers. Each layer is tampered 25 times with at standard tamping rod. The test
sample is weighed and placed in the test cylinder in three layers each layer being
tampered again. The specimen is subjected to a compressive load of 40 tonnes
gradually applied at the rate of 4 tonnes per minute. Then crushed aggregates
are then sieved through 2.36 mm sieve and weight of passing material (W2) is
expressed as percentage of the weight of the total sample (W1) which is the
aggregate crushing value.

 A value less than 10 signifies an exceptionally strong aggregate while above 35
would normally be regarded as weak aggregates.


14.  Abrasion test
 Abrasion test is carried out to test the hardness property of aggregates and to
decide whether they are suitable for different pavement construction works. Los
Angeles abrasion test is a preferred one for carrying out the hardness property
and has been standardized in India (IS:2386 part-IV). The principle of Los
Angeles abrasion test is to find the percentage wear due to relative rubbing
action between the aggregate and steel balls used as abrasive charge.
 Los Angeles machine consists of circular drum of internal diameter 700 mm and
length 520 mm mounted on horizontal axis enabling it to be rotated (see Figure
2). An abrasive charge consisting of cast iron spherical balls of 48 mm diameters
and weight 340-445 g is placed in the cylinder along with the aggregates. The
number of the abrasive spheres varies according to the grading of the sample.
The quantity of aggregates to be used depends upon the gradation and usually
ranges from 5-10 kg. The cylinder is then locked and rotated at the speed of
30-33 rpm for a total of 500 -1000 revolutions depending upon the gradation
of aggregates.
 After specified revolutions, the material is sieved through 1.7 mm sieve and
passed fraction is expressed as percentage total weight of the sample. This
value is called Los Angeles abrasion value.
 A maximum value of 40 percent is allowed for WBM base course in Indian
conditions. For bituminous concrete, a maximum value of 35 is specified.

15.  Impact test
 The aggregate impact test is carried out to evaluate the resistance
to impact of aggregates. Aggregates passing 12.5 mm sieve and
retained on 10 mm sieve is filled in a cylindrical steel cup of internal
dia 10.2 mm and depth 5 cm which is attached to a metal base of
impact testing machine. The material is filled in 3 layers where each
layer is tamped for 25 number of blows. Metal hammer of weight
13.5 to 14 Kg is arranged to drop with a free fall of 38.0 cm by
vertical guides and the test specimen is subjected to 15 number of
blows. The crushed aggregate is allowed to pass through 2.36 mm
IS sieve. And the impact value is measured as percentage of
aggregates passing sieve ( ) to the total weight of the sample ( ).


16.  Soundness test
 Soundness test is intended to study the resistance of aggregates to
weathering action, by conducting accelerated weathering test
cycles. The Porous aggregates subjected to freezing and thawing
are likely to disintegrate prematurely. To ascertain the durability of
such aggregates, they are subjected to an accelerated soundness
test as specified in IS:2386 part-V. Aggregates of specified size are
subjected to cycles of alternate wetting in a saturated solution of
either sodium sulphate or magnesium sulphate for 16 - 18 hours
and then dried in oven at to a constant weight. After five cycles,
the loss in weight of aggregates is determined by sieving out all
undersized particles and weighing. And the loss in weight should
not exceed 12 percent when tested with sodium sulphate and 18
percent with magnesium sulphate solution.

17.  Shape tests
 The particle shape of the aggregate mass is
determined by the percentage of flaky and elongated
particles in it. Aggregates which are flaky or
elongated are detrimental to higher workability and
stability of mixes.
 The flakiness index is defined as the percentage by
weight of aggregate particles whose least dimension
is less than 0.6 times their mean size. Test procedure
had been standardized in India (IS:2386 part-I)

18.  Bitumen adhesion test
 Bitumen adheres well to all normal types of road aggregates
provided they are dry and free from dust. In the absence of water
there is practically no adhesion problem of bituminous
construction. Adhesion problem occurs when the aggregate is wet
and cold. This problem can be dealt with by removing moisture
from the aggregate by drying and increasing the mixing
temperature. Further, the presence of water causes stripping of
binder from the coated aggregates. These problems occur when
bitumen mixture is permeable to water. Several laboratory tests are
conducted to arbitrarily determine the adhesion of bitumen binder
to an aggregate in the presence of water. Static immersion test is
one specified by IRC and is quite simple. The principle of the test is
by immersing aggregate fully coated with binder in water
maintained at temperature for 24 hours. IRC has specified
maximum stripping value of aggregates should not exceed 5%.

19. SPECIFICATIONS FOR WASTE
PLASTIC
 a) Polyethylene:
 LDPE (Low Density Poly-Ethylene): Low density poly-ethylene this
plastic waste available in the form of carry bags generally in
stores these plastic bags are very thin and also easily available.
 HDPE (High Density Poly-Ethylene): Generally High-density poly-
ethylene type of plastic waste is available in the form of carry
bags and easily available in the market.
 b) Polypropylene: This plastic may be available in the form of
carry bags or solid plastic it’s depend upon the use and need of
the industries. It is available in the form of plastic bottles and
mat sheets etc.

20.  Methodology
 Dry process is recommended for isolated works. It is recommended
that the percentage of shredded waste plastic will be 8% by CRRI,
while the same is specified as 10% by Dr. Vasudevan. However, we
can adopt 8% as the optimum plastic content for blending the
bitumen in the construction of plastic roads. The details of the
process are given below. Bitumen of grades 60/70 or 80/100 can be
used as binder as in case of conventional method.

21.  With Mini Hot Mix Plant
 The stone aggregate mix (as per specification) is transferred to the mix
cylinder where it is heated to 1650c (as per the IRC specification) and
then it is transferred to the mixing puddler (Temperature can be
monitored using IR thermometer), while transferring the hot aggregate
into the puddler, calculated quantity of shredded plastics is sprayed
over the hot aggregate within 30seconds. The sprayed plastic films
melts and gets coated over the aggregate, thus forming an oily
coating.

 Similarly, the bitumen is to be heated to a maximum of 1600c in a
separate chamber and kept ready (The temperature should be
monitored to have good binding and to prevent weak bonding).

 At the mixing puddler, the hot bitumen is added over the plastic-
coated aggregate and the resulted mix is used for road construction.
The road laying temperature is between 1100c to 1200c. The roller
used is normal 8-ton capacity.

22.  For intensive works Central Mixing Plant can also be used.
 The operating Techniques for this are given below:

 The aggregate materials will be transferred to the cylinder through the
conveyer belt.
 • The shredded plastics will be sprayed over the aggregate while it is moving in
the conveyer belt.
 • The spraying is done by manual labors standing up on both side of the conveyer
belt of the central mixing plant.
 • The addition of plastics should be done quantitatively.

 The amount of binder to be added is calculated and monitored:
 • In the central mixing plant, at the control room the addition of bitumen is
monitored.
 • It is easy to know the amount of bitumen sprayed per minute inside the cylinder.

 Amount of plastic to be added is @8% of bitumen.

23.  For example, if the bitumen quantity per minute is 10Kg, the plastic need to be
added is 0.8 Kg. i.e. (A bucket can be used which can hold 0.8 Kg at a time)

 Now, as the aggregate moves in the conveyer belt, the shredded plastics, taken
in the bucket are sprayed with a speed of 0.8 Kg/1min with suitable mechanical
device or manually.

 In manual method, one person will be adding the shredded plastic on to the
conveyer belt. In the meantime, another person will keep ready another bucket
full of plastics so that the addition of plastics will be continuous. Thus, manual
labor can also be so chosen that the addition is done continuous. Two or three
labors will be on this work of addition of plastics.

 As the plastics is added over the aggregate, the mix (aggregate and plastics)
moves into the cylinder.

 As the stone is heated the plastic films get melted over the heated stone and get
coated. Slowly the plastics coated aggregate moves forward where this polymer
coated aggregate is mixed with bitumen. The polymer coated aggregate
bitumen mix is then transferred to the dipper.

24.  oPreparation of Plastic-Waste Coated Aggregate
 The aggregate is heated to around 1700C; the plastic waste shredded
to the size varying between 2.36mm and 4.75mm. This shredded
plastic waste is added over hot aggregate with constant mixing to give
a uniform distribution. The plastic gets softened and coated over the
aggregate. The hot plastic waste coated aggregates are mixed with
hot bitumen 60/70 or 80/100 grade (1600C).
 For shredding of solid plastic waste of poly-propylene ‘scrap grinding
machine’ is used. In this process, a solid plastic waste cut in small
pieces with the help of with two rotating and one fixed blades. This
whole process gives output in per hour rate.
 Following are the Specifications of Scrap Grinder
 • Output 7.5Kg/hr.
 • Length of rotor-200mm
 • Length of blade-200mm
 • No. of blades rotating-2Nos.
 • Fixed blade-1No.
 • Motor-3HP,900RPM

25. RESULTS AND DISCUSSIONS
 Aggregate Impact Value
 The coating of plastics improves Aggregate Impact Value, thus improving
the quality of the aggregate. Moreover, a poor quality of aggregate can
be made useful by coating with polymers. It helps to improve the quality
of flexible pavement. This shows that the toughness of the aggregate to
face the impacts. Its range should be less than 10%.

 Aggregate Crushing Value
 The aggregate with lower crushing value indicate a lower crushed fraction
under load and would give a longer service life to the road. Weaker
aggregate would get crushed under traffic load. It is clearly seen from
Table- that plastic-coated aggregates shows the lower crushing value and
which can be withstand to traffic load more efficiently than the plain
aggregates. The results show that the aggregates are within the range
according to ISS. Its range should be less than 30-35%.

26.  • Specific Gravity
 The specific gravity of an aggregate is an indirect measure of its
strength. The more specific gravity the more is the strength. The value
of specific gravity of plain aggregate is less as compare to that of
plastic coated aggregate. Since aggregates having low specific gravity
are generally weaker than those with higher specific gravity values, the
results say that the specific gravity of the aggregates are increased
increasing its strength. Its range should be within 2.5-3.0%.
 • Stripping Value
 Stripping value gives the effects of moisture upon the adhesion of
bituminous film to the surface particles of the aggregate. The plastic
coating to aggregates gives the nil value of stripping. It indicates that
the aggregates are more suitable for bituminous road construction
than plain aggregates. The results obtained of the control specimen are
within the range of the IRC standards whereas coating of the
aggregate reduces the affinity of the aggregate towards water. Its
range should be less than 25%.

27.  • Water Absorption
 The aggregate is chosen also on the basis of the moisture absorption
capacity. The aggregate when coated with plastics improved its quality
with respect to moisture absorption. The coating of plastic decreases the
moisture absorption and helps to improve the quality of the aggregate
and its performance in the flexible pavement. The results show that the
moisture absorption of the aggregate is within the range of IRC
specifications which reduced to nil due to coating. Its range should be
less than 10%.
 • Los Angeles Abrasion Value
 The repeated movement of the vehicle will produce some wear and tear
over the surface of pavement. This test gives that wear and tear in
percentage. Under this study the percentage of wear and tear values of
plastic coated aggregate is found to be in decreasing order with respect
to the percentage of plastics. When the Los Angeles abrasion value of
plain aggregate value is compared with the plastic-coated aggregates
the values are less for coated aggregates. The results obtained are within
the range hence can be used for the construction. Its range should be
less than 35%.

28.  Conclusion
 Plastic coating on aggregates is used for the better performance of
roads. This helps to have a better binding of bitumen with plastic
wasted coated aggregate due to increased bonding and increased
area of contact between polymers and bitumen. The polymer coating
also reduces the voids. This prevents the moisture absorption and
oxidation of bitumen by entrapped air. This has resulted in reducing
rutting, raveling and there is no pothole formation. The roads can
withstand heavy traffic and show better durability.
 1. Aggregate Impact value of control specimen was 5.43%. It reduced
to 4.91% for PP8 and 4.26% for PP10. Reduction in value was 10% for
PP8 and 22% for PP10. This shows that the toughness of the
aggregate was increased to face the impacts.
 2. Crushing Value was reduced from 19.2% to 13.33% and 9.82% for
PP8 and PP10 respectively. Value reduced by 30% for PP8 and 48%
for PP10. Low aggregate crushing value indicates strong aggregates,
as the crushed fraction is low.

29.  3. Specific Gravity of the aggregate increases from 2.45 for control
specimen to 2.7 for PP8 and 2.85 for PP10 due to plastic coating.
 4. Stripping Value was reduced from 8% for control specimen to nil
for PP8 and PP10. This shows that coated aggregate is more suitable
for bituminous construction than plain aggregates.
 5. Water Absorption is also reduced to nil for PP8 and PP10 from
1.7% for control specimen.
 6. Los Angeles Abrasion Value of the control specimen was found to
be 13.42%. Coating of polymer over aggregate for PP8 increased
abrasion value by 19.97% and 29.88%for PP10. This indicates the
hardness of the aggregate.

30. THANK YOU