Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 3, Pages: 967-970  
J. Environ. Treat. Tech.  
ISSN: 2309-1185  
Journal web link: http://www.jett.dormaj.com  
Study of Eco-Processed Pozzolan Characterization as  
Partial Replacement of Cement  
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Raihana Farahiyah Abd Rahman , Hidayati Asrah , Ahmad Nurfaidhi Rizalman , Abdul K.  
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Mirasa , M A A Rajak  
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Faculty of Engineering, Universiti Malaysia Sabah, 88400 Jalan UMS, Kota Kinabalu, Sabah, Malaysia  
Preparatory Centre for Science & Technology, Universiti Malaysia Sabah, 88400 Jalan UMS, Kota Kinabalu, Sabah, Malaysia  
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Received: 11/01/2020  
Accepted: 16/06/2020  
Published: 20/09/2020  
Abstract  
Eco-processed pozzolan (EPP) is a sustainable product recycled from spent bleaching earth (SBE). It is recently used as a blended cement.  
The pretreatment method of palm oil generates SBE as waste material in the refinery plant. Despite sending the SBE to the landfill, which  
can lead to environmental pollution, it is extracted to produce sustainable products. The physical, chemical, mineralogical, and microstructural  
characteristics of EPP were analysed. Furthermore, the conventional cement was substituted with 20% of EPP by cement mass in mortar.  
The compressive strength of mortar containing EPP was determined for the assessment of strength activity index (SAI) of EPP. EPP consists  
mainly of silica (SiO  
2 2 2 3 2 3  
), and the value of SiO , aluminium oxide (Al O ), and iron oxide (Fe O )combination was 68.98% which is more than  
5
0%. According to the ASTM C618 standard, EPP could be categorised in the Class C pozzolan. The major crystalline phase of EPP was α-  
quartz. Based on the micrograph image, EPP possesses some relatively spherical, irregular shaped, and agglomeration of its particles. At an  
early curing age, the compressive strength of the mortar was increased with the inclusion of 20% of EPP. A high value of SAI can be reached  
by mortar specimen with 20% of EPP.  
Keywords: Eco-processed pozzolan, Pozzolan, Strength activity index  
1
Introduction1  
Palm oil fuel ash (POFA) [5], milled waste glass powder [6],  
clay brick powder [7], sugarcane bagasse ash [8], and fly ash [9]  
have been investigated to be used to substitute conventional  
cement in mortar and concrete. Because of its high percentage of  
Crude palm oil refinery plant generates spent bleaching earth  
(SBE) for approximately more than 2 million tonnes per year  
globally [1]. Malaysia is known to produce a huge number of  
palm oil fruits. In the pretreatment process which is in the  
degumming and bleaching of crude palm oil stage, bleaching  
earth is added to produce refined palm oil. SBE is one of the  
products of crude palm oil refining process. In Malaysia, the SBE  
from a refinery plant is often sent to the landfills [2]. The SBE  
disposal at landfills can affect the greenhouse gas (GHG)  
emission due to the natural anaerobic degradation. Recently,  
EcoOils’ company provides a solution to recycle SBE to produce  
sustainable products. Eco-processed pozzolan (EPP) is one of the  
extracted products from SBE. The sustainable products extracted  
from SBE are shown in Figure 1.  
Recently, EPP has been used as blended cement. From the  
previous studies, research on EPP as a pozzolanic material is  
limited. Waste products with pozzolanic characteristics are  
utilised in concrete to substitute cement, thus minimising the use  
of cement [3]. The use of pozzolanic material to replace cement  
silica (SiO  
concrete [5]. The reaction of SiO  
2
), POFA has a high potential to substitute cement in  
in pozzolanic material with the  
2
calcium hydroxide produces more CSH gel. The CSH gel will  
make the hardened paste denser and enhance its strength and  
durability [10]. In this study, the properties and the strength  
activity index (SAI) of EPP were investigated. At 7 and 28 days  
of curing, ordinary Portland cement was substituted with 20% of  
EPP by cement mass in mortar to assess the SAI of EPP.  
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Materials and methods  
In this study, the EPP was collected from EcoOils, Lahad  
Datu. The EPP is as shown in Figure 2. The particle size of EPP  
was measured by using laser diffraction particle size analyser.  
The chemical oxides, mineralogical, and microstructural  
characteristics of EPP were investigated by using X-ray  
fluorescence (XRF), X-ray diffraction (XRD), and scanning  
electron microscope (SEM), respectively. The ordinary Portland  
cement was substituted with 20% of EPP by cement mass in  
2
could minimise the release of carbon dioxide (CO ) from the  
cement industry because the production of cement contributes to  
%–7% of global CO emissions [4].  
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2
Corresponding author: Raihana Farahiyah Abd Rahman, Faculty of Engineering, Universiti Malaysia Sabah, 88400 Jalan UMS, Kota  
Kinabalu, Sabah, Malaysia. Email: raihanarahmanacc@gmail.com.  
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Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 3, Pages: 967-970  
mortar.  
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EPP contains high percentage of SiO . The loss on ignition of EPP  
was 3.3% which is less than 6% as specified in the ASTM C618  
standard. From the chemical compositions result, the EPP can be  
categorised as a Class C pozzolan according to the ASTM C168  
standard.  
Table 1: Physical properties of EPP  
Physical  
Properties  
Particle size, Mean particle Particle Specific  
10 (μm) size, d50 (μm) size, d90 gravity  
μm)  
d
(
OPC  
EPP  
3.37  
7.04  
27.4  
29.3  
94.36  
80.42  
3.27  
1.93  
Table 2: Chemical oxides properties of EPP  
Figure.1: Production of eco-processed pozzolan  
Chemical  
Properties  
(%)  
SiO2  
Al O  
Fe O CaO MgO LOI  
2
3
2
3
The sand was prepared according to the ASTM C778  
standard. The mixture with water-to-binder (W/B) ratio of 0.48  
was prepared. The mortar specimens with the dimension of 50 ×  
OPC  
EPP  
14.4  
47.6  
3.6  
11.6  
3.2  
9.8  
72.3  
12.5  
1.7  
6.2  
5.78  
3.3  
5
0 × 50 mm in size were cast. The compressive strength test of  
3
.4 Mineralogical and microstructural properties  
The XRD analysis of EPP and OPC are shown in Figure 3.  
the specimens was performed according to the ASTM C109  
standard. The pozzolanic activity of EPP was investigated by  
determining its SAI based on the ASTM C311 standard.  
The existences of a broad peak at 20° to 30° indicate the presence  
of amorphous phase in the EPP. The peak at 20° to 30° also shows  
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the existence of SiO , which is comparable to the information  
from the previous study [11]. The major crystalline phase of EPP,  
which is α-quartz was detected at 2θ angles of 26.63°, 20.86°, and  
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0.20°. Meanwhile, the minor crystalline phases: cristobalite,  
hematite, calcite, and α-Al were also identified in the  
2
O
3
diffractograms of EPP. Cristobalite peak was detected at 2θ angle  
of 28.03°. Meanwhile, the 2θ angles of 33.21° and 29.44° were  
assigned to hematite and calcite, respectively. The peaks at 31.31°  
correspond to the presence of mullite, while the peaks at 35.68°  
and 39.44° were assigned for α-Al  
The mineralogical analysis shows that the EPP consists of  
different minerals as it possesses SiO either in the crystalline  
2 3  
O .  
2
phase or the amorphous phase. The pozzolanic reactivity of  
material can be relied more on the occurence of its amorphous  
phase than other properties of the material [12]. The results are in  
agreement with the chemical composition findings from previous  
Figure.2: Eco-processed pozzolan  
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studies which show that EPP contains high SiO content.  
Meanwhile, the presence of mullite and α-Al corresponds to  
the presence of Al as stated in Table 2. In addition, the  
detection of hematite and calcite conform the presence of Fe  
2
O
3
3
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Results and discussions  
.2 Physical Properties  
Table 1 reveals the physical properties of EPP and OPC. The  
mean particle size, d50 of EPP and OPC was 29.3 and 27.4 μm,  
respectively. The particle size, d90 of EPP and OPC was 80.42 and  
2
O
3
2
O
3
3
and calcium carbonate (CaCO ) as discussed in the chemical  
composition findings.  
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4.36 μm, respectively. Based on the results, the specific gravity  
The micrograph images of EPP and OPC are shown in Figure  
4. The SEM image shows that the EPP particles was irregularly  
shaped, relatively spherical, and agglomerated, while OPC was  
irregular in shape. EPP has a porous texture on its particles.  
of EPP and OPC was 1.93 and 3.27, respectively. The EPP has a  
lower specific gravity than the OPC.  
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.3 Chemical properties  
Table 2 reveals the chemical oxides of EPP and OPC. The  
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.5 Strength activity index  
The SAI of control mortar (reference mortar) is supposed to  
XRF result reveals that the EPP composed of SiO  
the combination value of SiO , aluminium oxide (Al  
oxide (Fe ) was 68.98%. The value is less than 70% as  
according to the ASTM C618 standard. However, it is more than  
0% which the EPP can be classified in the Class C pozzolan. The  
2
at 47.6% and  
2
O ), and iron  
2 3  
be 100% at the curing ages of 7 and 28 days. The SAI of EPP and  
control specimens are shown in Figure 5.  
2
O
3
5
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Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 3, Pages: 967-970  
Figure.3: XRD patterns of OPC and EPP  
(a) OPC  
(b) EPP  
Figure.4: Micrograph images of OPC and EPP  
The figure shows that the compressive strength of specimens  
increased with the inclusion of 20% of EPP compared to that of  
the control specimens. The SAI of EPP at both curing ages of 7  
and 28 days was 114.4% and 104.2%, respectively, and the values  
are more than the minimum requirement value of 75% according  
to the ASTM C618 standard. It shows that the SAI of specimens  
at 7 days of curing was higher than that of the specimens at 28  
days of curing. The increase in SAI value of mortar containing  
EPP shows that EPP possesses pozzolanic properties. The high  
percentage of SiO and Al O in chemical compositions with  
2 2 3  
some amorphous phase in EPP might contribute to the pozzolanic  
properties of EPP to be used as cement replacement. The similar  
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Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 3, Pages: 967-970  
behaviour of material was reported in previous study [11]. The  
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Figure 5: Strength activity index (SAI) at 7 and 28 days  
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Conclusions  
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This paper concludes that EPP possesses pozzolanic  
(
2
properties as it consists high SiO amount and has the potential to  
Procedia Eng., vol. 148, pp. 487–493.  
substitute cement in mortar and concrete. The value of SAI of EPP  
satisfied the requirements of pozzolanic materials as according to  
the ASTM C618 standard and can be categorised as a Class C  
pozzolan. High value of SAI can be achieved by EPP at an early  
curing age. To a better sustainable mortar and concrete  
production, 20% of EPP can be used as cement replacement.  
Therefore, further reliable information of EPP is required to  
increase its usage in industries.  
0
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Aknowledgment  
The authors would like to acknowledge EcoOils, Lahad Datu  
for providing the EPP. Special thanks to laboratory technicians  
for their help.  
Ethical issue  
Authors are aware of, and comply with, best practice in  
publication ethics specifically with regard to authorship  
(avoidance of guest authorship), dual submission, manipulation  
of figures, competing interests and compliance with policies on  
research ethics. Authors adhere to publication requirements that  
submitted work is original and has not been published elsewhere  
in any language.  
Competing interests  
The authors declare that there is no conflict of interest that  
would prejudice the impartiality of this scientific work.  
Authors’ contribution  
All authors of this study have a complete contribution for data  
collection, data analyses and manuscript writing.  
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