INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
MANAGEMENT & APPLIED SCIENCE (IJLTEMAS)
ISSN 2278-2540 | DOI: 10.51583/IJLTEMAS | Volume XIV, Issue XI, November 2025
www.ijltemas.in Page 297
Enhancing Porous Asphalt with Fly Ash for Sustainable Development
Noraziyan Abd Aziz, Syahirah Mansor, Fairus Azwan Azizan
Faculty of Civil Engineering, University Technology MARA, Pulau Pinang Branch, Permatang Pauh
Campus, Malaysia
DOI: https://doi.org/10.51583/IJLTEMAS.2025.1411000029
Received: 10 November 2025; Accepted: 20 November 2025; Published: 03 December 2025
ABSTRACT
Porous asphalt pavement is a particular asphalt mixture made up of both fine and coarse aggregates bonded by
a bituminous binder. Although it has a rougher texture, porous asphalt looks like conventional asphalt on the
outside. In the past decade, porous asphalt pavement has gained popularity as a storm water best management
practice and utilize similar mixtures as those used for open-graded friction courses. Additive materials such as
fly ash, coal ash, and many more had been widely used successfully in the original specification of porous
asphalt mixtures to improve their durability and rutting resistance performance. In this study, fly ash has been
used to replace aggregate dust and the aggregate gradation limit in the porous asphalt mixture to determine the
Optimum Bitumen Content (OBC) as well as to improve rutting resistance and durability. The OBC was then
determined for all the mixes by Marshall Mix design. Laboratory specimens were prepared using 75 blows of
the Marshall hammer per side. The OBC for the conventional porous asphalt mix with aggregate dust was
found to be 6 percent, while the OBC for the modified porous asphalt mix with fly ash was found to be 5
percent. Rut depth for porous asphalt mixes with aggregate dust was lower (1.6 mm) compared with porous
asphalt mixes with fly ash (1.93 mm). This indicates that the additive material could efficiently retain the
binder in the mix. As a result, fly ash could be used as an alternative to aggregate dust in the porous asphalt
mixture.
Keywords—Aggregate dust, Fly Ash, Marshall Mix Design, Optimum Bitumen Content, Porous Asphalt.
INTRODUCTION
Porous asphalt pavement mixtures are designed with an open graded aggregate to increase the number of
permeable air voids, which allow water to penetrate through the voids, removing it from the surface of a
roadway much faster than traditional dense-graded pavement [1]. Porous asphalt is often weak and breaks due
to rutting behavior [2]. This failure occurs when the asphalt pavement cannot sustain continuously high traffic
loads for a long period of time. The main cause of rutting is the low strength of asphalt pavement due to the
poor physical strength of the materials. The tendency of the asphalt pavement to break during hot weather may
cause premature failure of the mix. To overcome this problem, additive material is being used to replace the
aggregate dust as the last aggregate gradation limit. Additive materials such as natural rubber have been widely
used successfully in the original specification of the porous asphalt mixtures. However, the cost of rubber
modified asphalt has been a long-term reason not to use it [5]. As an alternative to resolving this problem, fly
ash, also a type of additive material, was selected in this study to be used for porous asphalt mixtures as a cost-
and performance-effective solution.
Fly ash is a lightweight material that can be easily compacted; these properties can be useful in generating new
technologies for the development of highway projects that could further provide monetary savings in
transportation, construction, and material costs [3]. The use of fly ash in porous asphalt mixtures is worth
investigating, as the availability of fly ash resources in Malaysia will result in a lower production cost for
porous asphalt pavements. In addition, this material can provide an alternative, sustainable asphalt pavement
material [3].
INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
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ISSN 2278-2540 | DOI: 10.51583/IJLTEMAS | Volume XIV, Issue XI, November 2025
www.ijltemas.in Page 298
Hence, the main goal of this is to determine the Optimum Bitumen Content (OBC) as well as to evaluate the
performance of a modified porous asphalt mix using fly ash as the last aggregate gradation limit, and to
compare its performance with a conventional porous asphalt mix using aggregate dust as its last aggregate
gradation limit.
METHODOLOGY
Sample Collection
In this study, the fly ash was chosen based on its own physical and chemical characteristics. Fly ash is a by-
product from coal-fired electricity-generating power plants
[4]
. The sample of fly ash was obtained at an electric
power plant in Manjung, Perak, and it is shown in Figure 1.
Figure 1: Fly Ash powder
Sieve Analysis
The classification of aggregates is determined via sieve analysis. A mechanical sieve shaker can be used in the
laboratory to determine the size of each aggregate by using the vibration method. Aggregates will be retained
on the pan according to their pan size. The gradation of the combined coarse aggregate, fine aggregate, and
mineral filler was chosen to conform with the appropriate envelope in accordance with PWD Malaysia’s
Standard Specification for Road Works (JKR/SPJ/2008)
[6]
. Table 1 shows the aggregate gradation limits of the
ACW14 mixture.
Table 1: Gradation Limits of Combined Aggregates
BS Sieve Size, mm
Percentage Passing by weight
Grading A
Grading B
20
–
100
14
100
85 – 100
10
95 – 100
55 – 75
5
30 – 50
10 – 25
2.36
5 – 15
5 – 9
0.075
2 – 5
2 – 4
Aggregate Test
In this study, several aggregate tests have been conducted. Water absorption, LA abrasion, LA impact, and
flakiness index tests are among the aggregate tests that have been conducted to fulfil the objective of this
INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
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study.
Aggregate Grading
Based on the JKR Malaysia Specification gradation limit, a total weight of 1200g combined aggregate grading
consisting of aggregate sizes 14mm, 10mm, 5mm, 2.36 mm, and 0.075mm was prepared.
Bitumen Content
The bitumen added to the mixture is fixed by referring to JKR Arahan Teknik Jalan (JKR/SPJ/2008-S4)
[6]
.
The percentage of bitumen needed for the mixture varies from 4 percent to 6 percent, with an increment of 0.5
percent.
Sample Preparation
The porous asphalt mixtures were prepared in accordance with the Marshall method as specified in ASTM
D1559. Samples were prepared by replacing the aggregate dust with fly ash as the last aggregate gradation
limit. Three modified compacted samples are prepared for each bitumen content. Five bitumen contents are to
be tested to get the OBC.
Marshall Mix Design
A Marshall method was used to obtain the volumetric properties such as bulk specific gravity, Marshall flow,
Marshall stability, air voids, and voids filled with aggregate (VFA). This method is used for both conventional
and modified porous asphalt mixtures. In addition, from this method, the OBC for varying percentages of
bitumen content is also determined for both porous asphalt mixtures.
Performance Test
In this study, two performance tests were conducted: the binder draindown test and the rust susceptibility test.
Binder Draindown Test was determined by placing the weight of loose porous asphalt mixture in a basket. For
this study, the samples were prepared at optimal bitumen content. Meanwhile, for the rust susceptibility test, an
automated pavement analyzer (APA) was used in accordance with AASHTO TP63
[7]
. The test length was set
to 8000 cycles.
RESULT AND DISCUSSION
Combined Aggregates Grading
Table 2 shows the tabulation of combined fine aggregates and coarse aggregate. The total weight of the
combined aggregates graded is 1200g.
Table 2: Aggregate Grading for Porous Asphalt
BS Sieve
ACW14
% passing
% retained
Weight (g)
Accumulative Weight (g)
14
100
100
0
0
0
10
95 –
100
97.5
2.5
30
30
5
30 – 50
40
57.5
690
720
2.36
5 – 15
10
30
360
1080
0.075
2 – 5
3.5
6.5
78
1158
Pan
0
0
3.5
42
1200
INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
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Bitumen Content
Table 3 shows the percentage of bitumen content needed for porous asphalt mixtures. The percentage of
bitumen content is in the range of 4 percent to 6 percent in increments of 0.5 percent.
Table 3: Percentage of Bitumen Content needed in Porous Asphalt Mixtures
Bitumen (%)
Weight of Bitumen (g)
Total Weight (g)
4.0
48
1248
4.5
54
1254
5.0
60
1260
5.5
66
1266
6.0
72
1272
Volumetric Properties
Table 4 shows the results of the volumetric properties of porous asphalt mixtures using material according to
the Marshall method. Porous asphalt mixtures with aggregate dust contained higher values of air voids
compared to the porous asphalt mixtures with fly ash. This might also be the likely cause of the higher flow for
the aggregate dust, which is slightly above (3mm) the specification requirements. Moreover, the OBC for the
porous asphalt mixtures with aggregate dust and fly ash was found to be 6 percent and 5 percent, respectively.
Table 4: Volumetric Properties of the Porous Asphalt Mixtures
Volumetric
Properties
Porous Asphalt Mix Requirement
Conventional Porous
Asphalt (Aggregate Dust)
Modified Porous Asphalt
(Fly Ash)
Stability, N
Min 8000
12500
17900
Flow @ 3mm
2 – 4
3.0
0.773
Air Voids in
Total Mix @
21.5%
18 – 25
18.0
12.06
Optimum
Bitumen
Content
(OBC)
5 – 6
6.0
5.0
Binder Draindown
Binder draindown was calculated as the percentage of the binder that drained out of the basket by using Eq.
(1).
Binder Drainage (%) = (C-B)/A X 100 …Eq. (1)
Where;
A = Weight of initial total sample (g)
B = Weight of tray at starting time (g)
C = Weight of tray at final time (g)
The PWD Malaysia specification states that the maximum draindown value is 0.3% of the total mixture. The
percentage of binder drainage for each porous asphalt mixture is presented in Figure 2. Both mixes with
INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
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ISSN 2278-2540 | DOI: 10.51583/IJLTEMAS | Volume XIV, Issue XI, November 2025
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aggregate dust and fly ash met this requirement with draindown values of 0.3% and 0.167%, respectively. The
addition of additive material into the mix allows the asphalt to be more viscous and provides the ability to
retain asphalt during the drain out process when temperature increases.
Fig. 2: Binder Draindown for Porous Asphalt Mixes
Rutting Test
Fig. 3 shows the results of the rutting test carried out using the APA. Based on the figure, rut depth for both
mixes increases with the count of strokes under repeated passes of a loaded wheel. After the completion of
8000 cycles, the rut depth measured for aggregate dust is 1.6mm and for fly ash mix is 1.93mm. The higher rut
depth value for aggregate dust is likely due to the higher value of bitumen content used in the mix.
Figure 3: Rut Depth using APA for both mixes.
CONCLUSIONS
Based on the result obtained, it was observed that the performance of the porous asphalt mixture was
significantly affected with the addition of the selected material as a performance enhancer. Utilisation of
selected materials in the mixture can affect the volumetric properties, binder drainage, and performance to
resist rutting of the mixes. From the results of the laboratory work, the following conclusion can be made:
1. Modified porous asphalt mixtures using fly ash have a slightly lower OBC compared to conventional
porous asphalt mixtures using aggregate dust.
2. Modified porous asphalt mixtures using fly ash show better ability to retain the binder draindown of the
mixture compared to conventional porous asphalt mixtures using aggregate dust.
3. Aggregate dust shows higher resistance to rutting compared to fly ash due to the absence of mineral filler,
which is Ordinary Portland Cement (OPC).
INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
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ISSN 2278-2540 | DOI: 10.51583/IJLTEMAS | Volume XIV, Issue XI, November 2025
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Therefore, it can be concluded that additive material such as fly ash could be an alternative material to replace
the aggregate dust in porous asphalt mixes.
ACKNOWLEDGMENT
Most sincere thanks to Mrs. Suzana Manaf for her help in laboratory exercise in the completion of this project.
Many thanks also go to Geotechnical and Highway Transportation (GEOTREN) department of Universiti
Teknologi MARA, Pulau Pinang Branch. Not to forget, my sincere thanks to Mr. Affuan Hamid for his help in
laboratory exercise in Universiti Teknologi MARA Selangor for performance testing.
REFERENCES
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Design Methods for Porous Asphalt Mixtures 24(11): 1359-1367.
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3. Ramos, J. L. S. (2014). Sustainable Asphalt Pavement: Application of Slaughterhouse Waste Oil and Fly
Ash in Asphalt Binder. UMI Number: 1573599.
4. Rohini, I. & Arularasi. (2016). International Journal of Latest Research in Engineering and Technology
(IJLRET). Effect of Fly Ash and Quarry Dust as A Partial Replacement of Cement and Fine Aggregate in
Concrete (2454-5031): 15-33
5. Way, G. (2000). OGFC Meets CRM Where the Rubber meets the Rubber 12 Years of Durable Success
38(17): 567-569.
6. JKR Malaysia. (2008). Standard Specification for Road Works – Section 4: Flexible Pavement
(JKR/SPJ/2008-S4). Jabatan Kerja Raya Malaysia, Kuala Lumpur.
7. AASHTO. (2006). Standard Method of Test for Determining Rutting Susceptibility of Hot Mix Asphalt
(HMA) using the Asphalt Pavement Analyzer (APA), AASHTO Provisional Standards TP63, AASHTO,
Washington DC.
