Review on the Effect of Palm Oil Fuel Ash (POFA) on Concrete

Abstract

Previous studies show that the addition of admixtures to the concrete or mortar has given a positive result which lead to the increasing of engineering properties especially in strength. The different sizes of admixture added to the concrete also give another positive result. The more fines of the admixture sizes, more benefits the concrete will have. This paper review on the Palm Oil Fuel Ash (POFA) as a new pozzolan in the construction industry. The fineness of the admixture was compared to the fineness of the cement. Different past researcher use different method for the grinding process to get the admixture size which finer than cement size particles. Previous study done by the past researcher revealed that the higher fineness of the POFA has given a good result to the strength. It can be concluded that the fineness of POFA give good effects to the properties of the concrete or mortar

Full text

Journal of Industrial Engineering Research, 1(7) Special 2015, Pages: 1-4
IWNEST PUBLISHER
Journal of Industrial Engineering Research
(ISSN: 2077-4559)
Journal home page: http://www.iwnest.com/AACE/
Corresponding Author: Eddy S.R. Abdullah, Universiti Malaysia Sabah, Civil Engineering, Faculty of Engineering, Sabah,
Malaysia.
Review on the Effect of Palm Oil Fuel Ash (POFA) on Concrete
1Eddy S.R. Abdullah, 2Abdul K. Mirasa, 3Hidayati Asrah
1Universiti Malaysia Sabah, Civil Engineering, Faculty of Engineering, Sabah, Malaysia.
2Universiti Malaysia Sabah, Civil Engineering, Faculty of Engineering, Sabah, Malaysia.
3Universiti Malaysia Sabah, Civil Engineering, Faculty of Engineering, Sabah, Malaysia.
A RT I C LE I NF O
A B ST R AC T
Article history:
Received 13 June 2015
Accepted 5 August 2015
Available online 12 August 2015
Keywords:
Admixture
POFA
Fineness
Previous studies show that the addition of admixtures to the concrete or mortar has
given a positive result which lead to the increasing of engineering properties especially
in strength. The different sizes of admixture added to the concrete also give another
positive result. The more fines of the admixture sizes, more benefits the concrete will
have. This paper review on the Palm Oil Fuel Ash (POFA) as a new pozzolan in the
construction industry. The fineness of the admixture was compared to the fineness of
the cement. Different past researcher use different method for the grinding process to
get the admixture size which finer than cement size particles. Previous study done by
the past researcher revealed that the higher fineness of the POFA has given a good
result to the strength. It can be concluded that the fineness of POFA give good effects to
the properties of the concrete or mortar.
© 2015 IWNEST Publisher All rights reserved.
To Cite This Article: Eddy S.R. Abdullah, Abdul K. Mirasa, Hidayati Asrah, Review on the Effect of Palm Oil Fuel Ash (POFA) on
Concrete. J. Ind. Eng. Res., 1(7), 1-4, 2015
INTRODUCTION
In general, the ingredients of concrete consist of coarse aggregate, water, sand and cement. However, some
researcher found that another material that can be added to the concrete mixes which is called admixture. The
admixture is selected based on the concrete requirements. The admixtures are used to modify concrete
properties to achieve the requirement or performance. Mostly, the requirements and performances needed are to
control setting and early hardening, workability, increase in strength, reduction in water demand, improved
durability, impermeability and to control the heat of hydration.
For this paper, Palm oil fuel ash (POFA) will be discussed. POFA is categorized as mineral admixture.
POFA is agricultural by-products which possess pozzolanic properties due to its chemical composition which is
high in silica. Mehta [10] defined pozzolan as “siliceous or siliceous and aluminous materials which on
themselves posses little or no cementitious value but will in finely divided form and in the presence of moisture,
chemically react with calcium hydroxide at ordinary temperatures to form compound possessing cementitious
properties”
Due to the environmental issue, researchers take POFA as a sample for laboratory work since POFA is
abundant waste material which is useless. The idea to use POFA and other waste material to add into the
concrete mixes are due to this problem. Various researchers reported that POFA has pozzolanic properties and
highly reactive when the fineness is high and can be used as a unique cement replacement for building
construction materials [2,20].
Then, some researchers do a study on various size of the same admixture in a concrete or mortar. According
to Rukzon et al. [16] the fineness of the pozzolan is tending to have a large influence on the properties of
concrete through increases in the packing effect and pozzolanic activity. This will improves the durability
through pore refinement and reduce Ca(OH)2. A study by Megat Johari et al. [9] showed that the chemical
composition between ground POFA and ultrafine POFA also vary, where the content of SiO2 was increasing
when the POFA fineness increased. The fineness of POFA is increased by further burning process and grinding
process. Due to the further burning process, silica content is increased.
It is a well known fact that the increase in the fineness of pozzolanic material would lead to significant
increase in strength. The fine particles in concrete act as lubricant in the concrete mix and allow a reduction in
water content, for increasing the strength. The influence of ash fineness toward strength development of

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Journal of Industrial Engineering Research, 1(7) Special 2015, Pages: 1-4
concrete has been investigated by many researchers. The fineness of pozzolanic ash also tends to affect both the
fresh and hardened state properties of concrete [4]. Generally, the ash used as pozzolanic material needs to
produce in a finer size so that can function effectively in increasing the strength of concrete.
Table 1: Chemical Composition of treated POFA, [9].
Chemical Composition
Ground POFA (wt. %)
Ultrafine POFA (wt. %)
SiO2
51018
65.01
Al2O3
4.61
5.72
Fe2O3
3.42
4.41
CaO
6.93
8.19
MgO
4.02
4.58
SO3
0.36
0.33
K2O
5.52
6.48
Na2O
0.06
0.07
C
19.05
0.09
LOI
21.6
2.53
According to Jaturapitakkul et al. [8], the increased fineness of POFA will reduce the expansion and loss in
the compressive strength of concrete. For a same replacement of POFA in concrete with different fineness, a
higher fineness of POFA can produce greater strength of concrete as well as better performance against sulfate
attack [22]. Researcher found that the depth of carbonation will be increased with decreasing the fineness of
POFA for example the carbonation decreases when the high fineness of POFA is used [16].
2. Palm Oil Fuel Ash (POFA):
2.1. Production of POFA:
POFA is the solid waste produced from husk fibre and shell of palm oil burning by generation plant boiler
which generates energy to be used in palm oil mill in order to extract palm oil. Generally, after combustion
about 5% palm oil fuel ash by weight of solid wastes is produced [18].
POFA produced in Malaysia’s palm oil mill is dumped as waste without any profitable return [19]. It has
been approximated that the total solid waste generated by this industry has amounted to more than 8 million tons
a year [15]. From Malaysian Palm Oil board (MPOB) [13], Malaysia is now the second largest producer of palm
oil in the world, after being overtaken by Indonesia in 2006. In 2011, MPOB reported that the production of the
crude palm oil is more than 15 million tons. Due to this huge production of POFA, disposal issues arise. A lot
of cost needed to dispose this agricultural waste. Thus researchers come with an idea to use POFA in
engineering sector instead agricultural.
Table 2: Number Palm Oil Mills in Malaysia [13].
Year
Capacity
Million tonnes FFB/year
1980
149
13.33
1985
229
21.43
1990
261
31.03
1995
281
42.20
2000
350
65.95
2005
395
84.11
2010
421
97.38
2011
426
99.85
2.2 Treatment and grinding process of POFA:
The origin size of POFA is about 2.3mm which is coarser than cement size. By Tangchirapat [23], the
strength of concrete is influenced by the fineness of POFA and cement. So to improve the concrete properties,
the POFA is grinded. Hussin and Awal [1] found that the POFA has low pozzolanic reaction due to its large
particle size and porous structure, which could be enhanced by means of grinding. Thus, many researchers come
with method and procedure to produce high fineness of POFA.
Chandara et al. [5] suggested that the POFA was dried in an oven at 105 ± 5 °C for 24 h. and then sieved
through a 300 µm sieve to remove larger particles, fibres and grains that underwent incomplete combustion in
the palm oil mill. The POFA was then ground in a laboratory scale ball mill for 10 h to obtain ground POFA and
to achieve improved efficiency of the subsequent heat treatment. To eliminate unburned carbon, particle
agglomeration and crystallization of glassy phase which affect pozzolanic properties, the ground POFA was
heated at 500 ± 50 ºC for 90 min in a gas furnace. By Zeyad et al. [24], the heat treated POFA was then
subjected to further grinding via the same laboratory ball mill for 4 h to obtain the ultrafine POFA.
Recently, Megat Johari et al. [9] modified the treatment and grinding process of POFA production through
heat treatment in order to remove the excess carbon content and to decrease the median particle size of POFA by
about 2.06 µm. Different method from Yusuf et al., . POFA was first milled for 8 h to reduce its grain sizes
and then calcined at 500°C ± 50°C to remove its unburned carbon. The resulting product was then re- milled for

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Journal of Industrial Engineering Research, 1(7) Special 2015, Pages: 1-4
8 h to achieve ultrafine POFA. The SS was also milled for 16 h to achieve ground steel slag (GSS). The milling
was done with mechanical ball milling machine rotating at 180 rpm and contained 150 balls of different
diameters that ranged from 6 mm to 32 mm.
3. Performances of POFA: strength of POFA concrete:
Past research study on POFA give positive result and give benefits to the concrete or mortar. Study by
Neville [14] shows the applications of pozzolans in concrete give better result better than the normal concrete.
The strength of concrete can be improved by addition of admixture. The improvement of compressive strength
is due to pozzolanic reaction.
Some researcher that has been studying on POFA was successfully reveal the benefits of POFA in concrete
technology in terms enhancement towards the properties of concrete either strength or durability aspect [17].
Awal and Hussin [3] also proved that addition of POFA in concrete mixes can increase the resistance of
concrete toward sulphate and acid attack. Mannan [11] reported that POFA was used to replace portland cement
by 10, 20 and 30% by weight of cementitious materials to make high-strength concrete.
The addition of POFA in concrete mixes should be control. This is due to the bonding of the materials
during hardening. Massazza [12] reported that the strength of specimen will be decreased when POFA is added
too much in the concrete mix. Thus, POFA should be added in optimum proportion into concrete mixes. The
strength development of concrete may be affected by higher replacement level of cement by 50% POFA [2]. In
1996, Awal and Hussin [1] found that POFA concrete gain maximum strength when 30% of POFA is replace
into the mixes. New study done by Chindaprasirt et al. [7] reported that the concrete containing 20% of POFA is
high compressive strength compare ordinary portland cement (OPC) concrete and the compressive strength will
be reduced when the replacement percent increases.
Not even the addition of the POFA into mixes influence the properties of the concrete or mortar, but the
size of the POFA itself also affect the concrete. Awal and Hussin [2] reported that increasing the fineness of
POFA could produce greater concrete strength development compare to coarser one. Tangchirapat, [23] also
reported that the strength of concrete is influenced by the fineness of POFA and cement. The higher the fineness
of POFA, the greater is strength of the concrete as well as better performance against sulphate attack. The
compressive strength concrete reduced to large particles of POFA with high porosity which leads to increases in
the water-to-binder ratio of concrete. The fineness of the POFA will provide greater pozzolanic and due to the
small particles, it will fill the voids of the concrete mixes.
4. Benefits of addition POFA:
Studied by Awal and Hussin [2,3], Chindaprasirt [6,7], Jaturapitakkul [8], Rukzon [16], Sata [18], Tay [21],
and Tangchirapat [22,23], show that POFA have a good pozzolanic reactivity. POFA is used in concrete because
the environmental issue on dispose these agricultural wastes. Thus the addition POFA in concrete mixes will
solve the problem and also reduce cost of concrete production due to less cement usage. POFA with high
fineness can replace cement also improve the properties concrete. In other words, high fineness POFA can fulfill
the requirement in order to improve the performance of the concrete. POFA also have a potential in
suppressing expansion due to alkali-silica reaction. This reported by Awal and Hussin [2,3], Chindaprasirt [7],
Jaturapitakkul [8], and Tangchirapat [22] added that POFA produce good resistance against sulfate attack.
5.0 Conclusions and recommendations:
POFA that known as palm oil mill by-product are produce in million tons every year without any return
value which is caused environmental issue and highly cost in disposal of these agricultural waste. In order to
solve this problem, POFA is being used in production of concrete. Thus it can reduce the cost for disposal
management, space for disposal is reduced, and usage of cement also will be reduced. It can be said that reusing
POFA gives a lots of benefits in financial, environmental also engineering sector.
In order to use POFA in concrete or mortar mixture, based on reported by past researcher, the size of the
POFA should be smaller. The fineness should be high. Origin size of POFA which is low in fineness does not
give any contribution to get or achieve better strength in concrete [23].
The origin size of POFA is not suitable use in concrete or mortar mixes. This is due to the low pozzolanic
reaction. This will cause concrete having a low compressive strength and easily attacked by sulfate (low sulfate
resistance [8]. REFERENCES
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