How to cite:
Kardiman , Sabaruddin , Abdul Gaus. (2022). Analysis of the Use of
Coal Waste (Bottom Ash) as a Substitute for Aggregate in a Thin
Layer Mix of Asphalt Concrete. Journal of Eduvest. Vol 2(9): Page
1817-1826
E-ISSN:
2775-3727
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Eduvest Journal of Universal Studies
Volume 2 Number 9, September, 2022
p- ISSN 2775-3735 - e-ISSN 2775-3727
ANALYSIS OF THE USE OF COAL WASTE (BOTTOM ASH)
AS A SUBSTITUTE FOR AGGREGATE IN A THIN LAYER
MIX OF ASPHALT CONCRETE
Kardiman
1
, Sabaruddin
2
, Abdul Gaus
3
Civil Engineering Study Program, Faculty of Engineering, Khairun University,
Indonesia
123
Email: [email protected]
1
2
,
3
ABSTRACT
PLTU Tidore produces coal waste in the form of bottom ash or
(FABA) which produces an average of 14 tons per day or
5,040 tons per year. To reduce the amount of waste, which
can reduce production costs and reduce industrial waste,
namely by using bottom ash as a substitute for fine
aggregate. The specifications in the implementation of this
test refer to the General Bina Marga 2018 specifications. The
compaction of the test object is carried out in 2 × 75 collisions
assuming that the test is intended for heavy traffic. The test
results show that the bottom ash content as an aggregate
substitute for fine aggregate produces a stability value of
1437 kg, flow 3.23 mm, MQ 450.11 kg/mm, density 2.377
gr/cm³, and porosity 4.71%. The values of flow, density,
stability, MQ, porosity and porosity meet the requirements of
the values set in Revision II of Highways (2018). ITS test of hot
mixture HRS-BASE with the addition of bottom ash in the
optimum asphalt content of 925.39 Kpa
KEYWORDS
Bottom ash; ITS; Lataston
This work is licensed under a Creative Commons
Attribution-ShareAlike 4.0 International
INTRODUCTION
Asphalt concrete as a material for road construction has long been known
and is widely used in road construction. Its use in Indonesia is increasing from
year to year (General, 1987). (Ashari, 2020) . This is because asphalt concrete has
several advantages compared to other materials, including its relatively cheaper
Kardiman , Sabaruddin , Abdul Gaus
Analysis of the Use of Coal Waste (Bottom Ash) as a Substitute for Aggregate in
a Thin Layer Mix of Asphalt Concrete
1818
price than concrete, its ability to support high vehicle weight loads and can be
made from locally available materials and has good weather resistance. (Moses,
Airports, & Mampearachchi, 2020) . Asphalt concrete or asphaltic concrete is a
mixture of continuously graded aggregate with bituminous materials. (Hawari &
Lizar, 2021) (Wahyuri, 2011)
According to Bhattacharya et al, Bottom ash is the residue from coal
combustion at the PLTU which is currently not widely used and is only disposed
of as waste (Buritatum et al., 2022) . Even though bottom ash coal still has a fairly
high calorific value. Biomass generally has a fairly low density, so it will be
difficult to handle. In general, biomass densification has a uniform size and
quality. (Dou et al., 2017) (Siddique, 2014) .
The technology that is currently being developed is the management of
industrial waste to be used as raw materials or construction and infrastructure
materials originating from the Tidore PLTU as a power plant with a capacity of
2x7 MW. Where the Tidore PLTU produces coal waste in the form of bottom ash
or (FABA) which produces an average of 14 tons per day or 5,040 tons per year
(Dou et al., 2017) (Singh & Chaurasia, 2022) .
With the invention of these material innovations, it is hoped that they can
replace construction and infrastructure materials so that they can reduce
production costs and reduce industrial waste. One of these innovations is to use
bottom ash as a substitute for fine aggregate. An idea arose to conduct research on
"Analysis of the Use of Bottom Ash Waste as Substitute Aggregate in Mixed
Asphalt Concrete Thin Layers"
RESEARCH METHOD
The method used in this study refers to Bina Marga in 2018. This research
was conducted at the Road and Asphalt Laboratory, Khairun University, Ternate.
In order for this research to run smoothly, the equipment and materials must first
be prepared.
A. Tools and materials
The equipment used in the implementation of this research, as follows:
1. Mold of the test object (mold).
2. A compactor having a flat cylindrical impact surface, weighing 4.536 kg
(10 lbs), free-falling height of 45.7 cm (18inc).
3. The compactor base consists of wooden beams (teak and similar),
measuring approximately 20x20x45cm (12”x12”x1”) and tied to the
concrete floor by four angled sections.
4. Scales equipped with hanging specimens with a capacity of 2 kg with an
accuracy of 1gr.
5. 250˚C . capacity temperature gauge
6. Jack to remove the test object
7. Vernier calipers
8. Other tools such as pots, stoves, spoons, spatulas, and gloves.
The materials used are as follows:
1. The asphalt used is asphalt with Penetration 60-70
2. Bottom ash used is the result of the burning of the Tidore City PLTU.
3. Coarse Aggregate used comes from Kali Oba
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B. Research Stage
1. Material Characteristics Test
This test aims to determine the physical properties of the material used
by referring to the specifications/standards that have been determined. The
standard used as a reference in this study can be seen in table 1.1
Table 1 Standard Specification
Material Type
Test
SNI Standard
Coarse
Aggregate
Specific gravity
Water absorption
Aggregate Wear
Sieve Analysis
Specification
SNI 1969:2016
SNI 1969:2016
SNI 2417:2008
SNI ASTM C 136:2012
SNI 03-6819-2002
Fine Aggregate
Specific gravity
Water Absorption
Sieve Analysis
Specification
SNI 1970:2016
SNI 1970:2017
SNI ASTM C 136:2012
SNI 03-6723-2002
Filling
Material
ductility
Penetration
Softening Point
SNI 2432:2012
SNI 2456:2011
SNI 2434:2011
Asphalt
Flash point and burn point
Losing Weight
Specific gravity
SNI 2433:2011
SNI 06-2440-1991
SNI 2441:2011
2. Test Object Making
The specimens made are cylindrical in shape with an average diameter
of 10.16 cm (4") and an average height of 7.62 cm (3") for Marshall and ITS
specimens, while for UCS specimens, the diameter and height of the UCS
specimens are 10 cm, each variation made 3 test objects.
Table 2 Making Test Objects
No
Test
Number of Samples
Unit
% Bottom Ash to fine aggregate
0
20
40
60
80
100
%
1
Mashal
3
3
3
3
3
3
Fruit
2
ITS
3
3
3
3
3
3
Fruit
3
UCS
3
3
3
3
3
3
Fruit
Total Sample
54
Fruit
RESULTS AND DISCUSSION
A. Aggregate Inspection Results
In this case the inspection of aggregates for wear using the Los Angeles
machine, apparent density and water absorption indicate that the aggregates used
Kardiman , Sabaruddin , Abdul Gaus
Analysis of the Use of Coal Waste (Bottom Ash) as a Substitute for Aggregate in
a Thin Layer Mix of Asphalt Concrete
1820
have met the specified requirements (Dou et al., 2017) (Zhou et al., 2022) . The
results of the aggregate examination are presented in table 1.3
Table 3. Aggregate Inspection Results
No
Inspection
Results
Specification
Unit
Min
Max
1
Aggregate Density
A. Coarse Aggregate
2.50
3
Gr
- Bulk Type Weight
2.46
- SSD Type Weight
2.52
- Pseudo Type Weight
2.60
B. Medium Coarse Aggregate
2.50
3
Gr
- Bulk Type Weight
2.47
- SSD Type Weight
2.51
- Pseudo Type Weight
2.57
C. Stone Ash
2.50
3
Gr
- Bulk Type Weight
2.23
- SSD Type Weight
2.26
- Apparent Specific Gravity
2.30
2
Water Absorption
Rough
2.20
-
3
%
Medium Rough
1.55
Ash Rock
1.53
3
Aggregate Wear
32.55
-
40%
%
4
Flatness Index
22
-
25%
%
5
Mud and Clay Content
Rough
3.25
-
5
%
Medium Rough
4.25
Ash Rock
4
B. Asphalt Characteristics Inspection Results
The asphalt used in this research is hard asphalt with 60/70 penetration.
Asphalt inspection was carried out at the Road and Asphalt Laboratory, Khairun
University, Ternate. From the results of the inspection that has been carried out,
the asphalt still meets the specifications set by Bina Marga based on the Asphalt
Concrete Thin Layer Instructions (Lataston) No.16.1/SE/Db/2020.
C. Filler Inspection Results
This study uses rock ash filler from the Oba River which has been examined
at the Road and Asphalt Laboratory, Khairun University, Ternate. The stone ash
filler examination carried out is testing the specific gravity value. The
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examination that has been carried out has resulted in the specific gravity value of
the rock ash filler being 2.30 gr/cc.
D. Determination of Optimum Asphalt Content
The optimum asphalt content can be determined by performing the Marshall
test or what is often referred to as the Asphalt Institute method. In determining the
optimum asphalt content , the researcher used the data results based on the report
from the Public Works and Spatial Planning Department, UKPBJ Tidore Islands
(2021) with the package name for the Kahoho – Tayawi Road Section
Improvement (DAK).
From these values, it can be determined the best mixed properties or the
optimum asphalt content produced is 6.5 % which is then used as the basis for
making the next test object.
After knowing the value of the optimum asphalt content , then determine the
need for aggregate. To clarify the calculation, the following is an example of
calculating JMD for marshal and ITS specimens with a bottom ash content of 0%
and an asphalt content of 6.5% of the total weight of the mixture.
Table 4 Composition of aggregates for Masrhal and ITS . specimens
Calculation of Material Requirements
No
Material
Asphalt
Level
% Of Aggregate
Aggregat
e Rate
Sample
Weight
(Gr)
1
Rough
6.50%
35%
93.5%
359.98
2
Medium
Rough
40%
411.40
3
Ash Rock
25%
257.13
4
Liquid
Asphalt
71.5
71.50
Mold Capacity
1100
1100
For the filler, the researcher added cement that passed the #200 sieve at 0.07% of
the total weight of fine aggregate.
Before carrying out the Marshal Test, first carry out a volumetric test which
includes measuring the thickness of the test object, the weight of the test object in
a dry state, the weight of the test object in the SSD state and the weight of the test
object in water (Hawari & Lizar, 2021) .
This test aims to determine the characteristic value of the test object using
bottom ash (Gaus, Tjaronge, Ali, & Djamaluddin, 2015) . This test is carried out
using the Marshall test tool. From this test, marshall characteristics will be
obtained, namely the value of stability, flow, voids filled with asphalt (VFB),
voids in aggregate (VMA), voids in the mixture (VIM), and Marshall Quotient
Kardiman , Sabaruddin , Abdul Gaus
Analysis of the Use of Coal Waste (Bottom Ash) as a Substitute for Aggregate in
a Thin Layer Mix of Asphalt Concrete
1822
(MQ) (Irfansyah, Setyawan, & Djumari, 2017 ) (Zhu, Zhao, Zhao, & Gupta,
2020) .
Table 5 Volumetric and Marshall Calculation Recapitulation
Bottom
Ash
BJ.
BULK
CAMP.
VIM
VMA
VFB
STABILITY
FLOW
MQ
0
2,387
4.31
17.09
77.44
1190.00
3.43
347.94
20
2.380
4.58
17.32
76.33
1240.00
3.40
366.79
40
2.380
4.60
17.34
76.24
1309.57
3.37
419.72
60
2.377
4.71
17.44
75.77
1437.52
3.23
450.11
80
2.386
4.36
17.13
77.28
1408.55
3.30
426.74
100
2.386
4.34
17.11
77.39
1337.03
3.40
394.56
( Source: 2022; Road and Asphalt Laboratory, Khairun University, Ternate.)
From the recapitulation results for each percentage of bottom ash content , a
relationship can be made to obtain the optimum bottom ash content as shown in
Figure 1-4.
Figure 1. Graph of the relationship between bottom ash content and
stability
The addition of bottom ash into the asphalt mixture greatly affects the
stability value produced. The greater the percentage of bottom ash in the asphalt
mixture, the higher the stability value produced, but greater than the minimum
stability value
1190.00
1240.00
1309.57
1437.52
1408.55
1337.03
500.00
600.00
700.00
800.00
900.00
1000.00
1100.00
1200.00
1300.00
1400.00
1500.00
1600.00
0 20 40 60 80 100
STABILITY (KG)
BOTTOM ASH LEVELS(%)
Bottom Ash Vs Stability Relationship Graph
Eduvest – Journal of Universal Studies
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Figure 2. Graph of the relationship between bottom ash content and
flow
The flow value produced in this study does not meet the standard because it
is outside (2-4 mm). The resulting flow value is less than 2 mm on average, this is
caused by the addition of bath ash into the mixture asphalt can increase the
stiffness of the asphalt mixture (Ksaibati & Sayiri, 2006) .
Figure 3. Graph of the relationship between bottom ash content and
Marshall Quotient
The use of bottom ash filler can be concluded that the test object has rigid
properties caused by the material having a higher asphalt absorption than rock ash
(Lu et al., 2020)
3.43
3.40
3.37
3.23
3.30
3.40
2.00
2.50
3.00
3.50
4.00
4.50
5.00
0 20 40 60 80 100
FLOW (mm)
BOTTOM ASH LEVELS (%)
GRAPH OF THE RELATIONSHIP OF ASPHALT VS FLOW LEVELS
347.94
366.79
419.72
450.11
426.74
394.56
200.00
250.00
300.00
350.00
400.00
450.00
500.00
0 20 40 60 80 100
MARSHALL EQUIPMENT (kg/mm)
AIR CAVITY (%)
Bottom Ash VS Marshall Equipment RELATIONSHIP
GRAPH
Kardiman , Sabaruddin , Abdul Gaus
Analysis of the Use of Coal Waste (Bottom Ash) as a Substitute for Aggregate in
a Thin Layer Mix of Asphalt Concrete
1824
Figure 4. Graph of the relationship between bottom ash and porosity
The greater the percentage of addition of bottom ash in the asphalt mixture,
the greater the voids in the resulting mixture, this is due to the nature of the
pozzoland (Lynn, OBE, & Ghataora, 2016) . The pozzoland nature of bottom ash
causes the filler to agglomerate so that compaction is more difficult to do.
E. ITS Test Results (Indirect Tensile Strength)
From testing the test object using the ITS tool, the tensile strength is
obtained in lb units, then the tensile strength value is calculated in Kpa units.
Where previously the unit conversion was carried out from kg/m2 to Kpa. The
following is an example of unit conversion :
Test object code = 0%
The result of reading tensile strength = 50 lb = 50 x 0.454 kg = 22.70 kg
The result of calibrated tensile strength = 22.70 x 30.272
= 687.14 kg
The magnitude of the tensile strength is corrected according to the formula
1.1. are as follows:
ITS = ( 2 X Pi)/(π xdxh)
= 72948 ,45 kg/
m2
Conversion kg/
m2
→ kPa = 1137.9958 x 9.81 x 10
-3
= 715.62 Kpa
4.31
4.58
4.60
4.71
4.36
4.34
2.00
2.50
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
7.00
0 20 40 60 80 100
AIR CAVITY (%)
BOTTOM ASH LEVELS (%)
GRAFIK HUBUNGAN KADAR Bottom Ash VS VIM
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Figure 5. ITS Test Graph
From figure 5. it can be seen that after the test, the test object only
experienced cracks and did not split into two parts. This shows that the actual test
object has a good adhesion value. Based on graph 5, it shows that the bottom ash
content of 60% has a higher tensile strength.
CONCLUSION
From the results of research and data analysis that has been carried out, it
can be concluded that; Marshall hot asphalt mixture when used for HRS-BASE
using bottom ash content as a substitute for fine aggregate produces a stability
value of 1437 kg, flow 3.23 mm, MQ 450.11 kg/mm, density 2.377 gr/cm³, and
porosity 4.71%. The values of flow, density, stability, MQ, porosity and porosity
meet the requirements of the values set in Revision II of Highways (2018). So
overall the Lataston mixture with the addition of bottom ash has met the
requirements for use as a road pavement layer; ITS testing of hot mixture HRS-
BASE with the addition of bottom ash in the optimum asphalt content of 925.39
Kpa .
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