pureportal.coventry.ac.uk€¦ · web viewplastic bags; bitumen; structural strength;...
TRANSCRIPT
Impacts of Low-Density Polyethylene (Plastic Shopping Bags) on
Structural Performance and Permeability of HMA Mixtures
Chayanon Boonyuid
Faculty of Engineering, Environment & Computing
Coventry University, Priory St, Coventry, West Midlands, CV1 5FB, United Kingdom,
E-mails: [email protected]
Dr. Shohel Amin MCIHT FHEA (corresponding author)
Lecturer in Civil Engineering (Highways & Transportation Engineering),
Research Associate, Institute for Future Transport and Cities
Faculty of Engineering, Environment & Computing
Coventry University, Priory St, Coventry, West Midlands, CV1 5FB, United Kingdom,
E-mails: [email protected]
1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Impacts of Low-Density Polyethylene (Plastic Shopping Bags) on
Structural Performance and Permeability of HMA Mixtures
Abstract
This paper examines the optimum contents of bitumen (by weight of aggregates) and Low-
Density-Polyethylene (LDPE) plastic (by weight of bitumen) to ensure the long-term
performance of HMA mixtures. The coefficient of permeability of HMA samples with
different contents of bitumen and LDPE was estimated to understand rainwater infiltration
rate. The Marshall Mix Design Procedures ASTM D1559-76 were applied to estimate the
Marshall stability and flow values. The falling head method of permeability test estimates the
water infiltration rate. The results show that the optimum bitumen content (5.5-6% by weight
of aggregates) with higher contents (15% by weight of bitumen) of plastic materials increase
structural stability, reduce permanent deformation, increase ductility, and improve fatigue life
of HMA mixtures. This study also finds that permeability of HMA mixtures decreases rapidly
for 4% to 4.5% of bitumen contents. Impermeability for all type of HMA mixtures increases
slightly with 1% to 4% air voids. Findings of this study complement to studies on plastic
materials in bituminous pavements such as: (1) estimation of optimum contents of both
bitumen and plastic materials in HMA mixtures and (2) estimation of permeability
coefficients with different proportion of both bitumen and plastic contents to understand the
impacts of plastic materials on the permeability of bituminous pavement.
Keywords: recycle; plastic bags; bitumen; structural strength; permeability; hot-mix-asphalt
2
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
1. Introduction
Plastics are widely used in daily life and are the impetus to technological transformation
because of their noteworthy functions and resourcefulness (Zalasiewicz et al. 2016; North
and Halden 2013). The cumulative production of plastics as of 2015 can wrap the entire Earth
in a layer of cling film, and project production of plastics by 2050, that is about 40 billion
tons, can wrap the Earth by six layers (Rochman et al. 2013). Plastics in the environment are
divided broadly into macro-plastics (particles greater than 5 mm in diameter) and micro-
plastics. Macro-plastics include plastic bags, plastic bottles, discarded fishing nets, plastic
toys, and sections of plastic piping (Zalasiewicz et al. 2016). Production of Low-Density
Polyethylene (LDPE), also known as plastic shopping bags, is approximately 500 billion
units a year around the world causing major waste problems for environment and marine life
(Burd 2008; Barnes 2009; Zalasiewicz et al. 2016; Manju et al. 2017; Knoblauch 2009). A
recent study of Korean beaches found that 300–1000 wastes per 100m included polystyrene
fishing buoys, plastic bags and plastic bottles (Hong et al., 2014).
Thailand is one of the world’s worst offenders for dumping plastic waste into the sea
(Praiwan and Apisniran, 2019). The Pollution Control Department in Thailand estimated that
the production of plastic wastes was increasing at an annual rate of 12 per cent, that is
approximately 2 million tonnes and only 0.5 million tonnes of this waste could be reused
(Wongruang 2018). The remaining 1.5 million tonnes plastic wastes are single-use plastic
bags and trash in the ecosystem and environment (Wongruang 2018). The Thai government is
planning to ban the single-use plastics by 2022 that include lightweight plastic bags (less than
36 microns thick), food containers for takeaway, plastic cups and plastic straws. The plan
also targets to use 100% recycled plastic by 2027 through the application of various methods,
3
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
including turning waste into energy. Recycling plastic wastes reduces the environmental
pollutions but incurs additional costs (Denne et al. 2007; El-Saikaly 2013; Cruz et al. 2014).
The recycled plastic wastes mixed with bitumen can result into cheaper bituminous
pavements with increased longevity comparing to the conventional pavements. Several
studies investigated the effects of plastic wastes on Stone Mastic Asphalt (SMA) and Hot
Mix Asphalt (HMA) (Appiaha et al. 2017; El-Saikaly 2013; Manju et al. 2017; Modarres and
Hamedi 2014; Dalhat and Al-Abdul Wahhab 2017). Appiaha et al. (2017) found that plastic
wastes increased the durability, fatigue life and deformation resistance of bituminous
pavements. Similarly, El-Saikaly (2013) stated that addition of plastic in asphalt binder
improved the resistance of rutting and thermal cracking and reduced the fatigue damage and
stripping in bituminous pavement. Plastic materials also reduce the plastic shrinkage cracks
and increase the abrasion and slip resistance of bituminous pavement (Manju et al. 2017).
Ahmadinia et al. (2011) stated that thermoplastic polymer could strengthen the performance
of SMA mixture by increasing rigidity and resistance under heavy traffic loads. Ahmadinia et
al. (2011) tested the volumetric and mechanical properties of SMA mixes with 0%, 2%, 6%,
8% and 10% waste plastic bottles (Polyethylene Terephthalate, PET). Moghaddam et al.
(2012) investigated the effects of PET on stiffness and fatigue properties of SMA mixtures at
optimum asphalt contents at a temperature of 20oC and concluded that stiffness modulus
increased and decreased with lower and higher percentage of PET contents, respectively.
Modarres and Hamedi (2014) compared the stiffness and fatigue behaviour of PET with the
conventional polymer additive (styrene butadiene styrene) in asphalt mixtures and revealed
that PET had higher performance at 20oC but the fatigue life was lower at 5oC. Kamada and
Yamada (2002) indicated that polyethylene and polypropylene plastic materials could
improve the fluidity-resistance of dense graded asphalt mixtures. Awwad and Shbeeb (2007)
4
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
mixed High-Density Polyethylene (HDPE) and LDPE in the aggregate coating in grinded and
not grinded forms, respectively. Awwad and Shbeeb (2007) claimed that HDPE with 12% by
weight of bitumen provided the better stability of mixtures. However, Hınıslıoglu and Agar
(2004) argued that 4% of HDPE increased the resistance of SMA mix against deformation
and deterioration by 50%.
Al-Hadidy and Yi-qiu (2009), Zoorob and Suparma (2000) found that the durability and
stability of asphalt mixtures increased by mixing LDPE. Manju et al. (2017) assessed the
advantages of using plastic waste in asphalt mixture and concluded that plastic waste reduced
10% requirement of bitumen in HMA, increased the fatigue life and performance of
pavement under traffic loads. However, Manju et al. (2017) used mixed plastic wastes
including plastic carry-bags, disposable cups and PET bottles that have different properties
and melt at different temperatures. Dalhat and Al-Abdul Wahhab (2017) investigated the
effects of mixed plastic wastes (PP, HDPE and LDPE) on the viscoelastic performance of
asphalt binder and stated that plastic wastes improved the rutting and fatigue performance of
bituminous pavement.
This paper selected the LDPE as the bitumen modifier for higher flexibility ductility, fatigue
life and impact strength and requires less melting temperature comparing to other
polyethylene. The PET and HDPE used in previous studies require higher temperature to melt
and mix with aggregates and bitumen comparing to LDPE. Previous studies on plastic
materials as the additive of asphalt pavement only estimated optimum contents of plastic
materials. Moreover, previous experiments mixed the aggregates before adding bitumen that
require higher energy costs. This paper experiments the optimum contents of bitumen and
plastic contents to ensure the long-term performance of HMA pavements.
5
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
The use of plastic waste in bituminous pavement increases the film thickness and cohesion of
bitumen binder and aggregates in HMA that reduce the permeability of pavement (Kashem
2012; Fishback et al. 1997). The impermeable pavement may cause flooding in heavy rainfall
region such as Thailand. Studies on plastic wastes and bituminous pavements only focused on
the effects of plastic wastes on physical properties of pavement, however, deliberately
ignored their effects on the permeability of pavement. This paper examines the coefficient of
permeability of HMA mixtures with different contents of bitumen and LDPE to understand
rainwater infiltration rate. The experiments were performed at the Department of Rural Roads
laboratory of the Thai government.
2. Laboratory experiments
This study carries out in three steps: sample preparation, structural strength and permeability
tests (Figure 1). This study experimented 5 samples of aggregates mixed with different
proportions of bitumen and LDPE (Figure 2). The bitumen binder is AC 60/70, a penetration
graded measuring softness/hardness of asphalt cement. The sieve sizes and dense grade of
aggregates used in HMA mixture are shown in Table 1. The aggregates were washed and
dried in the oven at 100-120°C for 24 hours and each sample was prepared with 1200 grams
mixed aggregates (Figure 3a and 3b). Aggregates and moulds were heated in the oven at a
temperature of 160 to 180°C for 16 - 24 hours (Figure 3c).
6
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
Mixed at a temperature of 140-160°C
Shopping bags collected from local
households
Shredded at approximately 5-10
mm size
Figure 1: Flow chart of laboratory experiments
Figure 2: Proportions of bitumen and plastic contents in HMA samples
Table 1: Sieve sizes and dense grade of aggregates in HMA mixture (Asphalt Institute 2014)
Sieve size (No.) Gradation limits Used gradation
¾ 100 100
½ 80 – 100 91.7
3/8 70 – 90 77.9
No.4 44 – 77 62.9
7
Plastic (% by weight of bitumen)
Bitumen (% by weight of HMA sample)
Bitumen, Aggregates and plasticHMA samples
4%
0% 5%
4.5% 5% 5.5% 6%
10% 15%
143144
145
146
147
No.8 28 – 58 42.5
No.50 5 – 21 10.2
No.200 2 – 10 6.7
(a) Washed and dried aggregates with different sieve sizes
(b) Weighing and mixing aggregates
8
148
(c) Heating the aggregates and mouldsFigure 3: Preparation of aggregate mixtures
The plastic wastes were collected from local household and shredded at approximately 5-10
mm size (Figure 4a). Aggregates were mixed with bitumen binder (at first trial 4 % of
bitumen by weight of aggregates) at a temperature of 140-160°C and plastic wastes (5%
weight of bitumen) were mixed with the bitumen and aggregates (Figure 4b). The HMA was
compacted with 75 times of hammer blows and the samples were removed from the moulds
at a temperature less than 60°C (Figure 4c). The process was repeated for different proportion
of bitumen contents (4%, 4.5%, 5.0%, 5.5%, and 6.0% of total aggregates) with constant
portion of plastic materials (5% by weight of bitumen) to find out the optimum level of
binder content. The Marshall stability and flow values (Abo-Qudais and Al-Shweily 2007;
Dinis-Almeida et al. 2012; Gautam et al. 2018; Hınıslıoğlu and Ağar 2004; Jahanian et al.
2017; Nejad et al. 2010; Zaumanis 2010) were estimated applying Marshall’s Test
Procedures ASTM D1559-76 (Figure 4d). The HMA samples were manufactured with
different proportion of plastic within bitumen binder (5.0%, 10%, and 15%) to estimate the
optimum level of plastic content in the bitumen binder (Figure 4e and 4f).
9
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
(a) Household plastic wastes (b) Mixing plastic wastes with bitumen
binder
(c) Marshall mould and hammer (d) Marshall test ASTM D6927-15
(e) HMA with 5% plastic waste (f) HMA with 10% plastic waste
Figure 4: HMA sample preparation
10
166
The falling head method of permeability test was applied with 10.16 cm diameter and 25 cm
height pipes (Figure 5a). Each HMA sample was placed inside the middle of pipe, and the
silicone sealant was filled to seal out water around the edge of HMA samples (Figure 5a).
The pipe was filled up with water, the top head of water was measured, and time and
temperature were recorded (Figure 5b). The pipe top was closed to avoid evaporation and
measures of top head of water were taken every 1-hour interval during the 4-hour period to
observe the water infiltration rate through HMA samples.
(a) Filling the silicone sealant (b) Measure the top head of water
Figure 5. Permeability test
11
167
168
169
170
171
172
173
174
175
176
177
178
179
3. Data analysis and Results
3.1. Structural strength and bonding properties of HMA mixtures
The structural strength and bonding properties of HMA pavement in presence of plastics
were experimented by Marshall Stability, density, air voids, flow, voids filled with bitumen
and Voids in mineral aggregate (VMA). Marshall Stability presents the compressive strength
of HMA pavements. Figure 3 represents the relationship between Marshall Stability (in
kilogram) and bitumen content (asphalt concrete in percentage). The Marshall Stability
increased to the optimum value with 5% to 5.5% bitumen content (mixed with plastic) by
weight of aggregates and decreased with additional bitumen content in the HMA pavement
(Figure 6). The increment of plastics in bitumen mixture enhanced the compressive strength
of HMA pavement. For instance, the Marshall Stability of HMA pavement with 5.5%
bitumen content (mixed with 15% plastic) is highest (1865 kg) comparing to other HMA
mixtures (Figure 6). The results indicate that asphalt mixture with optimum plastic and
bitumen contents has better stability than that without plastic content because HMA with
higher bitumen binder causes bleeding and lower resistance to permanent deformation. The
increase in stability can be attributed to improved adhesion between the aggregates, bitumen
and plastic contents. Higher stability reduces the structural damage of pavement under
repeated traffic loads. Figure 6 shows that the Marshall stability of HMA mixtures increases
with the increased contents of LDPE (15% by weight of bitumen) because LDPE has good
fatigue resistance, toughness, impact strength and excellent tear and stress crack resistance
(Sastri 2014).
12
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
4.00 4.50 5.00 5.50 6.00800.00900.00
1000.001100.001200.001300.001400.001500.001600.001700.001800.001900.002000.00
Stab
ility
(kg)
Figure 6: The relationship between Marshall Stability and bitumen contents (%)
The bonding properties such as density, flow, air voids, voids filled with bitumen and VMA
delineate the premature failures of HMA such as rutting, slippage, cracking and ravelling.
The density of HMA samples was highest for 5-5.5% content of bitumen in the mixture
(Figure 7a). The relationship between HMA density and plastic content is positive. For
example, 5.5% bitumen with 15% plastic content in the HMA mixture observed the highest
density (2.4 gm/cm3) (Figure 7a). Higher the density, the lower the percentage of air voids in
the pavement mixture resulting in low cracking, however, low air voids lead more plastic
flow (rutting) and pavement bleeding. The ratio of air voids also influence the thermal
behaviour of HMA mixture. HMA mixture with low air voids content has higher thermal
conductivity resulting in lower heating and cooling rates than asphalt with lower thermal
conductivity (Hassn et al. 2016). The proportion of air voids in a good HMA mixture must be
low enough to prevent the thermal cracking but should be high enough to prevent the
permanent deformation. The experimental tests of plastic mixed HMA samples show that air
voids in the samples were reduced with the increasing percentage of bitumen (Figure 7b).
13
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
The decreasing rates of air voids in HMA mixtures for 5% and 10% plastic contents in the
bitumen were similar, however, HMA samples with 15% plastic content observed sharp
decline of air voids resulting in higher thermal conductivity. Higher plastic content in HMA
mixture may be suitable for extreme winter climate because of reducing the effects of freeze-
thaw cycle on pavement cracking and potholes. HMA mixture with less than 2% air voids are
subjected to rut and shove under heavy traffic loads (Asphalt Institute 2014). HMA mixtures
with 5.5% to 6% bitumen content mixed with 15% plastic might propagate the permanent
deformation of flexible pavement (Figure 7b).
The air voids content in HMA mixture is very important for the longevity of pavement
structure. The disproportionate contents of air voids in HMA pavements reduce the stiffness
and strength, fatigue life, and durability; and increase the ravelling, rutting and moisture
damage. Understanding the importance of air voids for long-term pavement performance, this
study examined the Voids filled with bitumen (VFB) and VMA. VFB represents the
percentage of voids between the aggregate in the compacted mixture that are filled with an
effective bitumen content rather than by air voids. VFB is inversely related to VMA that
shows the available voids volume before adding bitumen and the volume of air voids
remaining in the mixture after compaction. Figure 7c shows that VFB increases with increase
in bitumen content and increase of plastic in bitumen augments the increase of VFB. VFB
represents the durability of pavement, for instance, lower VFB represents higher air voids,
lower density, and lower stability resulting in lower compressive strength of pavement. On
the contrary, higher VFB shows lower voids, higher density, and higher stability which
included greater compressive strength of pavement. VMA increases the durability of HMA
mixtures because of the film thickness on aggregate particles. Higher VMA in dry aggregates
ensures the availability of more space for coating bitumen results in more durable pavements.
14
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
Figure 7d shows that HMA samples with 5% and 10% plastic contents cause the greater
VMA in the 5.5% optimum bitumen content in the mixture. However, adding too much
plastic (15% plastic) in bitumen content shows lower value of VMA (Figure 7d).
4.00 4.50 5.00 5.50 6.002.3352.3452.3552.3652.3752.3852.3952.4052.415
1 (0% plastic wastes)2 (5% plastic wastes)3 (10% plastic wastes)4 (15% plastic wastes)
% AC. by wt. of Agg.
Den
sity
(g/c
m3)
4.00 4.50 5.00 5.50 6.001.00
3.00
5.00
7.00
1 (0% plastic wastes)2 (5% plastic wastes)3 (10% plastic wastes)4 (15% plastic wastes)
% AC. by wt. of Agg.
Voi
d %
(a) density and bitumen content (b) air voids and bitumen content
4.00 4.50 5.00 5.50 6.0050.00
60.00
70.00
80.00
90.00
100.00
1 (0% plastic wastes)2 (5% plastic wastes)3 (10% plastic wastes)4 (15% plastic wastes)
% AC. by wt. of Agg.
V. F
. B. (
%)
4.00 4.50 5.00 5.50 6.0013.00
14.00
15.00
16.00
17.00
1 (0% plastic wastes)2 (5% plastic wastes)3 (10% plastic wastes)4 (15% plastic wastes)
% AC. by wt. of Agg.
V. M
. A. (
%)
(c) voids filled with bitumen and
bitumen content
(d) voids in mineral aggregate and
bitumen content
15
243
244
245
246
4.00 4.50 5.00 5.50 6.008.00
9.00
10.00
11.00
12.00
13.00
1 (0% plastic wastes) 2 (5% plastic wastes)3 (10% plastic wastes) 4 (15% plastic wastes)
% AC. by wt. of Agg.
Flow
(0.
01")
(e) flow and bitumen content
Figure 7: Bonding properties of HMA samples
This study estimated the flow values of HMA mixtures with different proportion of bitumen
and plastic to examine the deformation of pavement at maximum load before failure. Lower
flow value shows better deformation resistance. The conventional HMA mixture (without
plastic content) shows that flow values increase significantly with increment of bitumen
content. Addition of plastic in bitumen reduces the flow values, for instance, 5% and 10%
plastic within 5.5% bitumen content in HMA mixtures show lower but similar values (Figure
7e). The flow values are lowest with 15% plastic contents in the HMA mixture because
higher percentage of plastic content causes the flow to decrease slightly while the stability
increases (Figure 7e). However, higher percentage of plastic contents in HMA mixtures
results in accelerated rate of thermal expansion during the hot weather.
16
247
248
249
250
251
252
253
254
255
256
257
258
259
260
3.2. Permeability of HMA mixtures
Impermeable pavement surfaces increase the volume of stormwater runoff that overburdens
the capacity of drainage networks and eventually causing floods particularly in urban areas
(Heweidak and Amin 2019). The coefficient of permeability (infiltration rate) was calculated
to study hydraulic behaviour of HMA samples mixed with different proportion of bitumen
and plastic contents. The density and air voids in HMA mixtures have significant impacts on
pavement permeability; for example, high air voids lead to infiltration of water in HMA
mixture (Ahmad et al. 2017). Compaction also increases the impermeability of pavement
(Awadalla 2015). The addition of plastic in HMA increases the impermeability by reducing
air voids in the mixtures. The estimation of coefficient of permeability (cm/s) for different
HMA samples shows that pavement permeability decreases rapidly for 4% to 4.5% of
bitumen content (Figure 8a). The impermeability of HMA mixtures increased with higher
plastic contents resulting from the replacement of air voids by plastics (Figure 8a).
The water absorption decreases with decreasing number and size of air voids interconnected
to surface. This study utilises the air void contents instead of bulk specific gravities because
of the differences in aggregate specific gravities between the mixes (NCHRP 2004). Figure
8b illustrates that higher plastic contents reduce the air void contents (high densities)
resulting in low water absorptions. The impermeability for all type of HMA mixtures
increased slightly with 1% to 4% air voids; however, the permeability increased with air
voids of more than 4% (Figure 8b). The aggregates size in HMA mixtures has significant
impact on the permeability of flexible pavement. This study used the mix proportion of the
aggregates with sieve sizes of 3/4”, 1/2”, and 3/8” and rock dust was 12:15:25:48 by mass,
respectively. The 50% proportion of rock dust by mass filled the air voids in HMA mixtures
partially responsible for impermeable pavement. The impermeable pavement reduces the
17
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
effect of water bleeding and pumping from water table during rainy season. It is obvious that
Infiltration rate of water is reduced due to the decreasing of voids in each sample. On the
contrary, impermeable pavement surfaces increase the volume of storm-water runoff that
overburdens the capacity of drainage networks and eventually causing floods particularly in
urban areas (Heweidak and Amin 2019).
AC 4.0% AC 4.5% AC 5.0% AC 5.5% AC 6.0%0.00E+00
2.00E-04
4.00E-04
6.00E-04
8.00E-04
1.00E-03
1.20E-03
1.40E-03
Plastic wastes 0% Plastic wastes 5%Plastic wastes 10% Plastic wastes 15%
% AC. by wt. of Agg.
Coeffi
cient
of P
erm
eabi
lity,
k (c
m/s
)
(a) Coefficient of permeability and bitumen contents
18
286
287
288
289
290
1 2 3 4 5 6 70
0.0002
0.0004
0.0006
0.0008
0.001
0.0012
0.0014
Plastic wastes 0% Exponential (Plastic wastes 0%)Plastic wastes 5% Exponential (Plastic wastes 5%)Plastic wastes 10% Exponential (Plastic wastes 10%)Plastic wastes 15% Exponential (Plastic wastes 15%)
Voids (%)
Coeffi
cient
of P
erm
eabi
lity,
k (c
m/s
)
(b) coefficient of permeability and air voids
Figure 8. Coefficient of permeability for HMA mixtures
4. Findings and discussion
The use of plastic wastes (LDPE) particularly at 10% and 5% proportions of bitumen in
HMA mixtures with 5.5% bitumen of total aggregates enhances the structural integrity and
reduces the moisture damage. Plastic as an additive material in HMA mixtures reduces the
aggregate weight by 0.5% to 1% that decreases approximately £126 material costs for
constructing 1000 m2 and 5 cm. thickness of HMA pavement with 600 kg recycled plastic
shopping bags.
The experimental results show that 5.5% and 6% bitumen are the optimal ratios when mixing
with aggregates and plastic wastes. The use of 6% bitumen in the HMA mixture is not
economically feasible rather 5.5% bitumen content is enough to maintain the standard of
19
291
292
293
294
295
296
297
298
299
300
301
302
303
Marshall mix design criteria (Table 3). The use of plastic in HMA mixtures increased the
compressive strength by approximately 1.4 to 1.7 times comparing to the regular HMA
mixtures as well as improved the resistance of thermal crack, fatigue life, moisture damage
and rutting that ensure the longevity of pavement structure.
Table 3: Test Summary
Test Summary Normal
HMA
5% of plastic
wastes
10% of plastic
wastes
15% of plastic
wastes
Density (g/cm3) 2.386 2.388 2.388 2.403
Marshall Stability (kg) 1052.9 1165.8 1588.8 1865.7
Flow (0.01") 11.2 10.4 10.2 9.80
Air void (%) 2.75 2.67 2.67 2.06
Voids filled with
bitumen (%)
81.56 82.02 83.89 85.62
Voids in mineral
aggregate (%)
14.91 14.84 14.52 14.31
Coefficient of
Permeability, k (cm/s)
0.000302 0.000265 0.000173 0.000129
The HMA mixtures with plastic contents reduce the environmental pollution and HMA
material costs due to the recycling of plastic waste especially in developing countries that
experience higher manufacturing of plastic bags but might cause higher rainwater surface
runoff because of impermeable pavement structure. The solid plastics (polyvinyl chloride,
PVC; Polystyrene, PS; and Polypropylene, PP) should be removed from the LDPE before
mixing with HMA mixtures because PVC, PS and PP may emit harmful gases such as hydro-
20
304
305
306
307
308
309
310
311
312
313
314
315
316
chloride acid, phthalates, carbon monoxide, acrolein, formic acid, acetone, formaldehyde,
acetaldehyde, toluene and ethylbenzene and brominated flame retardants at high temperature.
The contamination of these toxic gases with rainwater surface runoff has long-term health
effects for human and animals (Talsness et al. 2009; Kyaw et al. 2012; North and Halden
2013). Moreover, use of plastic contents in bitumen (AC60/70) especially in hot weather
regions may propagate melting of bitumen. Future studies should work on the pavement
impermeability and contamination risk of rainwater surface runoff and ground water table
from harmful gases of plastic wastes.
5. Conclusions
Plastic shopping bags are causing major waste problems for the ecosystem. Despite the Thai
government plan to ban plastic shopping bags by 2022, plastic shopping bags lingering on the
planet will continue to cause problems for environment and marine life. The recycled plastic
wastes mixed with bitumen can create the bituminous pavements cheaper and increased
longevity comparing to the conventional pavements. This paper examines the optimum
contents of bitumen and LDPE contents with different proportions of bitumen (4%, 4.5%,
5%, 5.5% and 6% by weight of aggregates) and plastic (5%, 10% and 15% by weight of
bitumen) contents to ensure the long-term performance of HMA mixtures. The coefficient of
permeability of HMA samples with different contents of bitumen and LDPE was estimated to
understand rainwater infiltration rate. The Marshall’s Test Procedures ASTM D1559-76 were
applied to estimate the Marshall stability and flow values. The falling head method of
permeability test estimates the water infiltration rate. The experiments were performed at the
Department of Rural Roads laboratory of the Thai government. Based on the obtained results
the following conclusions can be drawn:
21
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
Optimum binder content was 5.5% by weight of total aggregates that was used to
assess the effective percentages of bitumen on the strength and performance
characteristics of different HMA mixtures.
Marshall Stability of HMA pavement with 5.5% bitumen content (mixed with 15%
plastic) is highest (1865 kg) comparing to other HMA mixtures.
The density was highest (2.4 gm/cm3) for 5-5.5% content of bitumen with 15% plastic
content in the mixture.
Higher the density, the lower the percentage of air voids in the pavement mixture
resulting in low cracking, however, low air voids lead more plastic flow (rutting) and
pavement bleeding.
Air voids in the samples were reduced with the increasing percentage of bitumen. The
decreasing rates of air voids in HMA mixtures for 5% and 10% plastic contents in the
bitumen were similar, however, HMA samples with 15% plastic content observed
sharp decline of air voids resulting in higher thermal conductivity.
HMA mixtures with 5.5% to 6% bitumen content mixed with 15% plastic might
propagate the permanent deformation of flexible pavement.
VFB increases with increase in bitumen and plastic contents resulting in higher
durability of HMA mixtures.
HMA samples with 5% and 10% plastic contents cause the greater VMA in the 5.5%
optimum bitumen content in the mixture.
Marshal flow values increase significantly with increment of bitumen content.
Addition of plastic in bitumen reduces the flow values, for instance, 5% and 10%
plastic within 5.5% bitumen content in HMA mixtures show lower but similar values.
22
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
Pavement permeability decreases rapidly for 4% to 4.5% of bitumen content.
Impermeability for all type of HMA mixtures increased slightly with 1% to 4% air
voids.
The use of LDPE in HMA mixture is economically feasible not only for the reduction of
bitumen in HMA mixture and but also for recycling of plastic wastes. The use of LDPE in
HMA mixtures increases the impermeability. Findings of this study complement to studies on
plastic materials in bituminous pavements such as: (1) estimation of optimum contents of
both bitumen and plastic materials in HMA mixtures and (2) estimation of permeability
coefficients with different proportion of both bitumen and plastic contents to understand the
impacts of plastic materials on the permeability of bituminous pavement. Future studies
should work on the pavement impermeability and contamination risk of rainwater surface
runoff and ground water table from harmful gases emitted from plastic wastes.
Data Availability Statement
All data, models, or code generated or used during the study are available from the
corresponding author by request.
References
Abo-Qudais, S., and Al-Shweily, H. (2007). ‘Effect of aggregate properties on asphalt
mixtures stripping and creep behaviour.’ Construction and Building Materials, 21(9),
1886-1898. https://doi.org/10.1016/j.conbuildmat.2005.07.014
Ahmad, A. F., Razali, A. R., Razelan, I. S. M., Jalil, S. S. A., Noh M. S. M., and Idris, A. A.
(2017). ‘Utilization of polyethylene terephthalate (PET) in bituminous mixture for
improved performance of roads.’ IOP Conference Series: Materials Science and
Engineering, 203, 012005. 10.1088/1757-899X/203/1/012005.
23
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
Ahmadinia, E., Zargar, M., Karim, M. R., Abdelaziz, M., and Shafigh, P. (2011). ‘Using
waste plastic bottles as additive for stone mastic asphalt.’ Materials and Design, 32(10),
4844-4849. https://doi.org/10.1016/j.matdes.2011.06.016
Al-Hadidy A. I., and Yi-qiu T. (2009). ‘Effect of polyethylene on life of flexible pavements.’
Construction and Building Materials, 23(3), 1456–64.
https://doi.org/10.1016/j.conbuildmat.2008.07.004
Appiaha, J. K., Nana, V., Boateng, B., and Tagbor, T. A. (2017). ‘Use of waste plastic
materials for road construction in Ghana.’ Case Studies in Construction Materials, 6, 1-7.
https://doi.org/10.1016/j.cscm.2016.11.001
Asphalt Institute (2014). ‘Mix Design Methods for Asphalt.’ 7th ed., MS-02. Asphalt
Institute. <https://www.slideshare.net/QasimMasood1/ms-2-7th-edition> [November 1,
2018].
Awadalla, M. (2005). Field and Laboratory Investigation of Asphalt Pavement Permeability,
Carleton University, Ottawa, Canada.
Awwad, M. T., and Shbeeb, L. (2007). ‘The use of polyethylene in hot asphalt mixtures.’
American Journal of Applied Sciences, 4(6), 390–396.
Barnes, D. K. A., Galgani, F., Thompson, R. C., and Barlaz, M. (2009). ‘Accumulation and
fragmentation of plastic debris in global environments.’ <
http://rstb.royalsocietypublishing.org/content/royptb/364/1526/1985.full.pdf> [November
1, 2018]
Burd, D. (2008). ‘Plastic Not Fantastic.’
<http://wwsef.uwaterloo.ca/archives/2008/08BurdReport.pdf> [October 9, 2018].
Cruz, N. F., Ferreira, S., Cabral, M., Simões, P., and Marques, R. C. (2014). ‘Packaging
waste recycling in Europe: is the industry paying for it?’ Waste Management, 34(2), 298-
308. https://doi.org/10.1016/j.wasman.2013.10.035
24
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
Dalhat, M. A., and Al-Abdul Wahhab, H. I. (2017). ‘Performance of recycled plastic waste
modified asphalt binder in Saudi Arabia.’ International Journal of Pavement Engineering,
18(4), 349-357. https://doi.org/10.1080/10298436.2015.1088150
Denne, T., Irvine, R., Atreya, N., and Robinson, M. (2007). ‘Recycling: Cost Benefit
Analysis.’ <https://www.mfe.govt.nz/sites/default/files/recycling-cost-benefit-analysis-
apr07.pdf> [November 1, 2018].
Dinis-Almeida, M., Castro-Gomes, J., and de Lurdes Antunes, M. (2012). ‘Mix design
considerations for warm mix recycled asphalt with bitumen emulsion.’ Construction and
Building Materials, 28(1), 687-693. https://doi.org/10.1016/j.conbuildmat.2011.10.053
El-Saikaly, M. A. (2013). ‘Study of the Possibility to Reuse Waste Plastic Bags as a
Modifier for Asphalt Mixtures Properties (Binder Course Layer)’, The Islamic University
of Gaza, Palestine.
Fishback, G. M., Egan, D. M., and Stelmar, H. (1997). ‘Plastic asphalt paving material and
method of making same. United States Patent 6000877.’ <
http://www.freepatentsonline.com/6000877.html> [November 1, 2018]
Gautam, P. K., Kalla, P. Nagar, R., Agarwal, R., Jethoo, A. S. (2018). ‘Laboratory
investigations on hot mix asphalt containing mining waste as aggregates.’ Construction
and Building Materials, 68, 143-152. https://doi.org/10.1016/j.conbuildmat.2018.02.115
Hassn, A., Aboufoul, M., Wu, Y., Dawson, A., and Gracia,A. (2016). ‘Effect of air voids
content on thermal properties of asphalt mixtures.’ Construction and Building Materials,
115, 327-335. https://doi.org/10.1016/j.conbuildmat.2016.03.106
Heweidak, M., and Amin, M. S. R. (2019). ‘Effects of OASIS® Phenolic Foam on Hydraulic
Behaviour of Permeable Pavement Systems.’ Journal of Environmental Management, 230,
212-220. https://doi.org/10.1016/j.jenvman.2018.09.084
25
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
Hınıslıoğlu, S., and Ağar, E. (2004). ‘Use of waste high density polyethylene as bitumen
modifier in asphalt concrete mix.’ Materials Letters, 58(3-4), 267-271.
https://doi.org/10.1016/S0167-577X(03)00458-0
Hong, S., Lee, J., Kang, D., Choi, H.-K., and Ko, S.-H. (2014). ‘Quantities: composition and
sources of beach debris in Korea from the results of nationwide monitoring.’ Marine
Pollution Bulletin, 84(1-2), 27–34. https://doi.org/10.1016/j.marpolbul.2014.05.051
Jahanian, H. R., Shafabakhsh, Gh., and Divandari, H. (2017). ‘Performance evaluation of Hot
Mix Asphalt (HMA) containing bitumen modified with Gilsonite.’ Construction and
Building Materials, 131, 156-164. https://doi.org/10.1016/j.conbuildmat.2016.11.069
Kamada, O., and Yamada, M. (2002). ‘Utilization of waste plastics in asphalt mixture.’
Memoirs of the Faculty of Engineering, Osaka City University, 43, 111–118.
Kashem, M. A. (2012). ‘Use of waste plastic blended bitumen for road construction and
maintenance.’ Bangladesh University of Engineering and Technology.
Knoblauch, J. A. (2009). ‘The environmental toll of plastics.’ <https://www.ehn.org/plastic-
environmental-impact-2501923191.html> [November 1, 2018].
Kyaw, B. M., Champakalakshmi, R., Sakharkar, M. K., Lim, C. S., and Sakharkar K. R.
(2012). ‘Biodegradation of Low Density Polythene (LDPE) by Pseudomonas Species.’
Indian Journal of Microbiology, 52(3), 411–419. 10.1007/s12088-012-0250-6
Manju, R., Sathya, S., and Sheema, K. (2017). ‘Use of Plastic Waste in Bituminous
Pavement.’ International Journal of ChemTech Research, 10(8), 804-811.
Modarres, A., and Hamedi, H. (2014). ‘Effect of waste plastic bottles on the stiffness and
fatigue properties of modified asphalt mixes.’ Materials and Design, 61, 8–15.
https://doi.org/10.1016/j.matdes.2014.04.046
26
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
Moghaddam, T. B., Karim, M. R., and Syammaun, T. (2012). ‘Dynamic properties of stone
mastic asphalt mixtures containing waste plastic bottles.’ Construction and Building
Materials, 34, 236–242. https://doi.org/10.1016/j.conbuildmat.2012.02.054
National Cooperative Highway Research Program (NCHRP) (2004). ‘Relationships of HMA
In-Place Air Voids, Lift Thickness, and Permeability.’ Volume 2, NCHRP Web Document
68 (Project 9-27), Transportation Research Board, USA.
Nejad, F. M., Aflaki, E., and Mohammadi, M. A. (2010). ‘Fatigue behavior of SMA and
HMA mixtures.’ Construction and Building Materials, 24(7), 1158-1165.
https://doi.org/10.1016/j.conbuildmat.2009.12.025
North, E. J., and Halden, R. U. (2013). ‘Plastics and environmental health: the road ahead.’
Reviews on environmental health, 28(1), 1-8. 10.1515/reveh-2012-0030
Panyakapo, P., and Panyakapo, M. (2007). ‘Reuse of thermosetting plastic waste for
lightweight concrete.’ Waste Management, 28, 1581–1588.
https://doi.org/10.1016/j.wasman.2007.08.006
Praiwan, Y., and Apisniran, L. (2019). ‘Drowning in a sea of plastic. Bangkok Post.’
<https://www.bangkokpost.com/thailand/special-reports/1704904/drowning-in-a-sea-of-
plastic> [November 15, 2019]
Rochman, C., Browne, M. A., Halpern, B., Hentschel, B. T., Hoh, E., Karapanagioti, H. K.,
Rios-Mendoza, L. M., Takada, H., Teh, S., and Thompson, R. C. (2013). ‘Classify plastic
waste as hazardous.’ Nature, 494, 169–171. https://doi.org/10.1038/494169a
Sastri, V. R. (2014). ‘Commodity Thermoplastics: Polyvinyl Chloride, Polyolefins, and
Polystyrene.’ In Plastics in Medical Devices: Properties, Requirements and Applications,
William Andrew, 73-120. https://doi.org/10.1016/B978-1-4557-3201-2.00006-9
Talsness, C. E., Andrade, A. J. M., Kuriyama, S. N., Taylor, J. A., and vom Saal, F. S.
(2009). ‘Components of plastic: experimental studies in animals and relevance for human
27
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
health.’ Philosophical Transactions of the Royal Society London, Series B, Biological
Science, 364(1526), 2079-2096. https://doi.org/10.1098/rstb.2008.0281
Vootukuri, V. R. R (2016). ‘Report on the utilization of waste plastic materials in asphalt
pavements.’ Southern Illinois University Carbondale, Illinois.
Wongruang, P. (2018). ‘Special report: Alarm raised as Thailand drowns in plastic trash. The
Nation Thailand.’ <https://www.nationthailand.com/national/30344702> [November 15,
2019]
Zalasiewicza, J., Waters, C. N., Ivar do Sul, J. A., Corcoran, P. L., Barnosky, A. D., Cearreta,
A., Edgeworth, M., Gałuszka, A., Jeandel, C., Leinfelder, R., McNeill, J. R., Steffen, W.,
Summerhayes, C., Wagreich, M., Williams, M., Wolfe, A. P., Yonana, Y. (2016). ‘The
geological cycle of plastics and their use as a stratigraphic indicator of the Anthropocene.’
Anthropocene, 13, 4–17. https://doi.org/10.1016/j.ancene.2016.01.002
Zaumanis, M. (2010). ‘Warm mix asphalt Investigation.’ PhD Thesis, Riga Technical
University, Kgs. Lyngby, Denmark
Zoorob, S. E., and Suparma, L. B. (2000). ‘Laboratory design and investigation of the
properties of continuously graded asphaltic concrete containing recycled plastics aggregate
replacement (plastiphalt).’ Cement and Concrete Composites, 22, 233–242.
https://doi.org/10.1016/S0958-9465(00)00026-3
28
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503