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Original Article
ISSN (Online): 2350-0530
ISSN (Print): 2394-3629
International Journal of Research - GRANTHAALAYAH
December 2024 12(12), 73–79
How to cite this article (APA): Soleman, S., Sultan, M.A., Kusnadi, and Marsaoly, N. (2024). The Effect of Using Fly Ash as a Cement
Substitute on the Quality of Nickel Slag-Based Paving Blocks. International Journal of Research - GRANTHAALAYAH, 12(12), 73–79.
doi: 10.29121/granthaalayah.v12.i12.2024.5875
73
THE EFFECT OF USING FLY ASH AS A CEMENT SUBSTITUTE ON THE QUALITY OF
NICKEL SLAG-BASED PAVING BLOCKS
Sadli Soleman 1, Mufti Amir Sultan 2, Kusnadi 2, Nurmaiyasa Marsaoly 2
1 Master of Civil Engineering Program Student, Khairun University, Ternate, Indonesia
2 Department of Civil Engineering, Khairun University, Ternate, Indonesia
ABSTRACT
The Rum Steam Power Plant (PLTU) uses coal as an energy source. The waste produced
from this process is in the form of solid waste with an amount of ±5% of the total waste.
This solid waste is in the form of bottom ash and fly ash with a content of 80-90% in the
form of bottom ash and the remaining 10-20% in the form of fly ash. Paving blocks are an
important element in urban infrastructure, used for roads, sidewalks and other public
areas. In recent years, attention to sustainability and the use of environmentally friendly
materials has increased. This research will focus on analyzing the interaction of these two
materials in paving block mixtures, with the aim of producing construction materials that
are more efficient and environmentally friendly. The research results show that the
substitution of cement with fly ash in paving blocks made from nickel slag has a
significant effect on the mechanical and physical characteristics. The use of fly ash up to
20% shows relatively good results with a reduction in compressive strength and density
that is not too significant, while the proportion of 30% shows a more drastic reduction.
Therefore, it is recommended to use a maximum proportion of 20% fly ash as a cement
substitute to achieve a balance between strength and sustainability.
Received 10 December 2024
Accepted 08 January 2025
Published 15 January 2025
Corresponding Author
Sadli Soleman, sadlisoleman@pu.go.id
DOI
10.29121/granthaalayah.v12.i12.202
4.5875
Funding:
This research received no
specific grant from any funding agency in
the public, commercial, or not-for-profit
sectors.
Copyright: © 2024 The Author(s).
This work is licensed under a Creative
Commons Attribution 4.0
International License.
With the license CC-BY, authors retain
the copyright, allowing anyone to
download, reuse, re-print, modify,
distribute, and/or copy their
contribution. The work must be
properly attributed to its author.
Keywords: Fly Ash, Nickel Slaf, Paving Block
1. INTRODUCTION
The development of environmentally friendly and sustainable construction
materials has received great attention from the construction industry. One of the
most significant activities emphasized by engineers and scientists in the
construction industry, specifically in the sectors using cement as a binding material,
is the exploration of raw materials that can improve the durability of concrete. This
effort is in line with the principles of sustainable construction, promoting the
development of green concrete and environmentally friendly building practices (Li
et al. (2004); Qingren et al. (2004)). The objective behind the concepts of green
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The Effect of Using Fly Ash as a Cement Substitute on the Quality of Nickel Slag-Based Paving Blocks
International Journal of Research - GRANTHAALAYAH
74
concrete and construction is to produce sustainable development without damaging
natural resources (Suhendro (2014)).
Currently, several industries in North Maluku generate waste that is unused.
For instance, in Tidore Kepulauan City, a Steam Power Plant (SPP) operates using
coal as its primary energy source, contributing to waste production. The process
generates solid waste, making up 5% of the total, consisting of 80-90% bottom ash
and 10-20% fly ash Assi et al. (2020). Waste is not managed systematically and is
instead disposed of in open areas. One potential approach to handling it is by
repurposing it as an additive material in civil engineering applications, such as in
concrete mixtures, mortar, bricks, paving blocks, and rigid pavements (Arshad et al.
(2021), Cho et al. (2019), Gopalakrishnan (2018), Pangestuti et al. (2024), Rahim et
al. (2020), Septiandini et al. (2021), Sultan et al. (2022)).
The Harita Nickel smelter, a nickel ore processing industry on Obi Island, South
Halmahera Regency, primarily produces ferronickel and generates about 1 million
tons of nickel slag annually. Along with the increase in production, more nickel slag
is produced, which can cause the accumulation of nickel slag piles. To prevent the
continued increase in nickel slag piles, it is necessary to find alternatives to the use
of nickel slag.
The Ministry of Environment and Forestry (KLHK), through Government
Regulation No. 22/2021, has officially excluded nine materials from the category of
hazardous and toxic waste (B3). According to Attachment XIV of the regulation,
these materials include iron and steel slag, nickel slag, mill scale, electric arc furnace
(EAF) dust, PS ball, fly ash and bottom ash (FABA) from SPP, spent bleaching earth
(SBE), and foundry sand.
The growing pace of development has led to an increasing demand for
construction materials. Currently, cement-based building materials, such as paving
blocks, are widely used by the public for various applications, such as footpaths, car
parks, sidewalks, parking lots, and roads in housing complexes. The increasing need
for building materials has led to the need for other raw materials as an alternative
to the production of paving blocks. Since 1972, the Center for Settlement Research
and Development, under the Ministry of Public Works, has conducted research and
promoted the use of waste materials in building production. This initiative supports
resource availability, aligns with government construction programs, and addresses
industrial challenges. Additionally, utilizing waste materials fosters the growth of
small businesses producing building components, adds value for waste managers,
and creates new job opportunities.
2. MATERIAL AND METHOD
2.1. LOCATION OF MATERIAL COLLECTION
The basic material to form paving blocks using nickel slag is obtained from the
nickel processing industry located on Obi Island, which is part of the administrative
area of South Halmahera Regency. Fly ash is used as a partial replacement for
cement as a binding material obtained from a steam power plant located on Tidore
Island, included in the administrative area of Tidore Islands City. Visualization of
each material used and the location of its collection are presented in Figure 1.
2.2. TEST OBJECTS
The mortar test specimens are 5x5x5 cm in size and paving blocks are 21x11x6
cm in size. The preparation of test specimens begins with a sieve analysis (ASTM
Sadli Soleman, Mufti Amir Sultan, Kusnadi, and Nurmaiyasa Marsaoly
International Journal of Research - GRANTHAALAYAH
75
C136-01, 2015), to remove slag particles that do not meet fine aggregate
specifications. Subsequently, tests are conducted for mud content, water content,
bulk density, and specific gravity in accordance with fine aggregate standards
(ASTM C 127-01 & ASTM C 128-01, 2001). Then, the preparation of fly ash with
retained sieve analysis No. 200.
The percentage of nickel slag as a substitute for cement used varies from 0%
(control test object), 10%, 20%, and 30% based on the comparison of cement
weight. The test object is in the form of a cube measuring 5x5x5 cm with a total of
100 pieces, then the test object is soaked in water for 28 days, after 28 days the
compressive strength and absorption tests are carried out (ASTM 109 (2009); ASTM
C642-97. (1997)).
Figure 1
Figure 1 Visualization of Material and Collection Locations in North Maluku
3. REUSLT AND DISCUSSION
3.1. COMPRESSIVE STRENGTH
The compressive strength test of paving blocks was carried out with a
composition of 1:2 and 1:3. The recapitulation of the compressive strength results
of paving blocks at the age of 28 days can be seen in Table 1.
Table 1
Table 1 Recapitulation of the Compressive Strength Results of Paving blocks with compositions 1:2 and
1:3
No Nickel
Slag
Variati
ons
Maximum Load and Compressive
Strength
Compressiv
e Strength
Difference
Compressi
ve
Strength
Reduction
Percentag
e
01:02
01:03
(kN)
(MPa)
(kN)
(MPa)
01:02
01:03
01:02
01:03
1
0%
55,40
22,32
38,80
15,09
-
-
-
-
2
10%
42,40
17,26
25,20
10,76
4,98
4,33
22,39%
28,69%
3
20%
29,80
12,60
25,80
7,81
9,63
5,11
43,31%
48,23%
4
30%
24,60
9,62
13,20
5,30
12,61
9,79
56,70%
64,87%
The Effect of Using Fly Ash as a Cement Substitute on the Quality of Nickel Slag-Based Paving Blocks
International Journal of Research - GRANTHAALAYAH
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The results of the compressive strength test of paving blocks at the age of 28
days caused a decrease in strength and the average compressive strength obtained
was as follows:
• Normal paving block 1:2 is 22.32 MPa, paving block containing 10% fly ash
is 17.60 MPa, paving block containing 20% fly ash is 12.60 MPa, and paving
block containing 30% fly ash is 9.62 MPa.
• Normal paving block 1:3 is 15.09 MPa, paving block containing 10% fly ash
is 10.76 MPa, paving block containing 20% fly ash is 7.81 MPa, and paving
block containing 30% fly ash is 5.32 MPa.
As more fly ash is added to the mortar and concrete mixture, the rate of strength
gain decreases. Fly ash affects the initial strength gain probably due to the presence
of free lime that is still reacting during the curing process. This may be because fly
ash provides enough lime needed to react with the pozzolan in the hydration
process. More lime inhibits the hydration process but is still sufficient to provide the
required design strength (Kumar & Bendapudi (2011)).
3.2. WATER ABSROPTION
Pengujian penyerapan air pada benda uji paving block dilakukan pada umur 28
hari dengan jumlah Water absorption testing on paving block test specimens was
carried out at the age of 28 days with a total of 5 test specimens for 2 compositions
1:2 and 1:3 respectively. The results of the measurement between water absorption
and fly ash composition are evident on the test specimens. The results of the paving
block absorption test at the age of 28 days can be explained as follows:
• Normal paving block 1:2 is 0.73%, paving block contains 10% fly ash is
1.21%, paving block contains 20% fly ash is 1.56%, and paving block
contains 30% fly ash is 2.22%;
• Normal paving block 1:3 is 1.10%, paving block contains 10% fly ash is
1.76%, paving block contains 20% fly ash is 2.18% and paving block
contains 30% fly ash is 2.70%.
Figure 2
Figure 2 Absorption of Paving Blocks with Fly Ash Variations
Sadli Soleman, Mufti Amir Sultan, Kusnadi, and Nurmaiyasa Marsaoly
International Journal of Research - GRANTHAALAYAH
77
3.3. QUALITY OF PAVING BLOCK
The quality standards for paving blocks refer to the Indonesian National
Standard (SNI-03-0691, 1996) as shown in Table 2.
Tabel 2
Table 2 Paving Block Class Standards
Quality Compressive strength
(MPa)
Maximum average water absorption -rata
maksimum
Average
Minimum
(%)
A 40 35 3
B 20 17 6
C 13 12,5 8
D
10
8,5
10
The quality of paving blocks based on compressive strength and absorption
tests is shown in Figure 3 and Figure 4.
Figure 3
Figure 3 Paving Block Quality 1:2 and 1:3 Based on Compressive Strength
Figure 4
Figure 4 Quality of Paving Blocks 1:2 and 1:3 Based on Absorption Level
The Effect of Using Fly Ash as a Cement Substitute on the Quality of Nickel Slag-Based Paving Blocks
International Journal of Research - GRANTHAALAYAH
78
Based on Figure 3 and Figure 4, the quality of paving blocks can be grouped as
follows:
• The composition of a 1:2 ratio of cement binder and nickel slag filler
material produces paving blocks (MS) classified as grade B. These paving
blocks are used for parking lots, housing complex roads, and car garages.
• The composition of 1:3 with cement binder and nickel slag filler material
produces paving blocks (MS) classified as grade C. These paving blocks
can be used for light traffic such as footpaths, pedestrians, or sidewalks.
• The composition of 1:2 with 80% cement binder + 20% fly ash (MS-20)
and a composition of 1:3 with 90% cement binder and 10% fly ash (MS-
10) produces paving blocks of grade D which can be used for road areas
with very low traffic such as parks and yards.
• In the composition of 1:2 with 70% cement binder + 30% fly ash (MS-30),
the composition of 1:3 with 80% cement binder and 20% fly ash (MS-20)
and the composition of 1:3 with 70% cement binder and 30% fly ash (MS-
30) paving blocks produced do not comply with the quality requirements
set by SNI-03-0691.
CONFLICT OF INTERESTS
None.
ACKNOWLEDGMENTS
None.
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