The Effect of Palm Oil Fuel Ash as Cement Additive on High- Strength Concrete
Nuradila Izzaty Halim1*, Aidan Newman1, Muhd Norhasri Muhd Sidek1,2, Hamidah Mohd Saman1, Megawati Omar3
1 School of Civil Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia
2 Institute for Infrastructure Engineering and Sustainable Management (IIESM), Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia
3 Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia
*Corresponding Author: [email protected] Accepted: 15 February 2023 | Published: 1 March 2023
DOI:https://doi.org/10.55057/ajfas.2023.4.1.4
_____________________________________________________________________________________________
Abstract: Palm oil production is one of the essential economies of Malaysia. Unfortunately, the by-product of this industry, a massive volume of palm oil fuel ash (POFA), may negatively impact the environment and human health. Hence, this study hypothesized that to reduce environmental or health hazards of the POFA, it could be reused as an additive or replacement in concrete.
However, the idea of using the POFA has been chiefly applied to standard-concrete grades, but the use of high-strength concrete in structures is increasing worldwide, including in Malaysia.
Hence this paper presents the experiment of the effect of POFA as an additive ranging between 0% and 15% to produce high-strength concrete with good workability. The tests conducted were the compression and slump tests. The specimen used in the compression tests were 100 mm concrete cubes tested in 3, 7, 14, and 28 days. It was found that the inclusion of 5% POFA as addictive to cement in concrete produced the highest compressive strength, 84.12 MPa, on the 28th day of testing. It was also found that its workability was as good as the control concrete.
Thus, the utilization of POFA could be considered an environmental-friendly cement additive to be used as supplemental cementitious material to produce workable high-strength concrete.
Keywords: Supplementary Cementitious Material, High-Strength Concrete, Palm Oil Fuel Ash, Workability, Compressive Strength
___________________________________________________________________________
1. Introduction
The palm oil planting area in Malaysia has risen rapidly since 1960. Palm trees were planted on 1.5 million hectares in 1985, 4.3 million hectares in 2007, and 4.917 million hectares in 2011. The Malaysian Palm Oil Board (MPOB) estimated that the total oil palm plantation area in Malaysia covered about 5.849 million hectares (MPOB, 2018). This increase has made Malaysia's palm oil economy the most significant commodity producer and was ranked the world's second-largest producer after Indonesia (Iskandar et al., 2018).
However, the massive production of palm oil produces a large amount of palm oil fuel ash (POFA).
After the oil extraction process, the palm fruit residues are burnt to generate electricity. The final
product of this burning process is the POFA. Noting the total solid waste produced by the palm oil industry in Malaysia, which was about ten million tonnes per year (Nagaratnam et al., 2016), the abundance of POFA disposed of in landfills has further led to the negative impacts on the environment, which also entails other problems.
However, scientists conjecture that POFA could be used to improve concrete. As a result, researchers have conducted studies on green concrete that used the POFA (Altwair & Kabir, 2010;
Hamada et al., 2018; Islam et al., 2015; Munir et al., 2015; Tay, 1990; Tonnayopas et al., 2016).
Their results revealed that the POFA contained a high amount of silicon dioxide in amorphous form and can be used as pozzolanic materials for concrete improvement. The silicon dioxide content reacts with Ca (OH)2 that comes from the hydration process and produces calcium silicate hydrate (C–S–H) gel compound, which improves the compressive strength of concrete (Sata et al., 2004).
High-strength concrete (HSC) is needed more in Malaysia as it progresses. The HSC has high durability and strength, which benefits more applications in the construction industry than normal- strength concrete. It is also commonly referred to as a 28-day cylinder compressive strength of more than 6000 psi (42 Mpa). Jagana & Vinod (2017) defined the HSC as one with a specified compressive strength between 40 to 100 N/mm2. For precast and in-situ works, 80 to 100 N/mm2 and higher strength are used. The HSC is beneficial since it can produce longer, lighter precast concrete and small columns.
Generally, the HSC can be achieved by a low water-cement ratio. A superplasticizer is added before fine, and coarse aggregates are added to produce a consistent paste. Then, the pozzolanic reaction adds supplementary cementing material to create additional strength. Since POFA has pozzolanic properties, it is considered suitable as a new supplementary cementing material in high- strength concrete. As such, high-strength concrete with the utilization of the POFA has been studied for compressive strength and durability (Ismail et al., 2010; Sata et al., 2004; Zeyad et al., 2017). However, their studies used the POFA as a cement replacement in high-strength concrete.
Also, literature references could not be found on the effect of POFA as an additive to cement in high-strength concrete. Therefore, this study aimed to assess the impact of the POFA as an additive on cement to produce better-performance concrete. The effects of the POFA as an additive to cement on concrete were investigated and tested on fresh and hardened properties such as slump and compressive strength tests. The results were compared with those in the control condition.
This experiment may also help resolve the landfill crisis and the environmental and waste management crises. In addition, it promotes environmental-friendly practices and develops new green concrete innovations in the construction industry.
2. Materials and Methods
The experiment consisted of activities undertaken in four (4) phases. First, the concrete mix was prepared in four (4) mixes. They were: OPC, 5POFA, 10POFA, and 15POFA. The four mixes were to assess their workability and strength. The second phase was the preparation of materials.
The materials used were Ordinary Portland Cement (OPC), POFA, aggregates, and admixture. The third phase was concrete curing, and the fourth was the concrete test.
Preparation of Concrete
This study highlighted the potential of POFA as an additive to cement in the concrete with different percentage levels of POFA at 5%, 10%, and 15%. Hence, four (4) different mixes were prepared;
OPC, 5POFA, 10POFA, and 15POFA, as shown in Table 1. The OPC was plain concrete which was termed a control. Then the 5POFA used 5% additive cement with the POFA, 10POFA used 10% additive cement with POFA and 15POFA 5% additive cement with it. Three samples were used to take an average strength, and these three samples were tested for 3, 7, 14, and 28 days.
Table 1: Design Mix
Mix Designation
Material kg/m3
Cement Coarse Aggregate Fine Aggregate Water Admixture POFA
OPC 800 800 433 160 16 -
5POFA 800 800 433 160 16 40
10POFA 800 800 433 160 16 80
15POFA 800 800 433 160 16 120
Preparation of Materials
The materials and specimens used in the preparation phase were 100 mm concrete cubes, Ordinary Portland Cement (OPC), aggregates, the POFA, water, and glenium as admixtures. The OPC was obtained from Tasek Corporation SDN. BHD. and the chemical properties of the OPC and POFA are shown in Table 2. Table 2 also shows that each mix is designated by 5%, 10%, and 15% of POFA.
The OPC was obtained from Tasek Sdn. Bhd. (ASTM: Type I) and the aggregates from the concrete laboratory of the engineering college, UiTM, Shah Alam. The coarse and fine aggregate was sieved by passing 10 mm and 4mm sieves, respectively. The POFA was obtained from the United Palm Oil SDN BHD's incinerated palm oil waste in Sungai Kecil, Nibong Tebal, Pulau Pinang, Malaysia.
Firstly, the POFA, after being collected, was dried in an oven for 24 hours to extract excess water.
After being dried, it was sieved to a size of 212m to eliminate the coarse aggregate. The sieved POFA was held in a clean, dry, and airtight humidity-controlled room in the laboratory to ensure purity. The potable tap water used to mix the concrete mix adhered to BS EN 1008. MasterGlenium ACE 8538, obtained from Badische Anilin und Soda Fabrik (BASF), No 2, Jalan Astaka U8/87, Bukit Jelutong, Seksyen U8, 40150 Shah Alam, Selangor Darul Ehsan, Malaysia. It was used in the analysis as an admixture (M).
Table 2: Chemical Properties of the OPC and POFA
Chemical Properties Oxide (%)
OPC POFA
Silicon Oxide (SiO2) 17.58 44.22
Aluminum Oxide (Al2O3) 3.37 3.61
Ferric Oxide (Fe2O3) 4.47 2.94
Calcium Oxide (CaO) 67.98 31.02
Sulfur Trioxide (SO3) 4.36 1.13
Magnesium Oxide (MgO) 0.83 0.24
Manganese oxides (MnO) 0.30 3.42
Phosphorus pentoxide (P2O5) 0.06 0.30
Titanium dioxide (TiO2) 0.24 6.93
Potassium Oxide (K2O) 0.81 44.22
Concrete Curing
After casting, the concrete cubes were removed from the mould and placed inside a full water tank for curing. They were cured in the tank for 3, 7, 14, and 28 days. The curing processes were conducted to maintain an adequate temperature of the concrete during its early age, which may affect the hydration of the cement and strength of the concrete. Then the cubes were removed from the tank and dried under the sun for at least two hours before the compression test.
Experimental Testing
The experimental testing comprised two tests: slump and compression.
Slump Test
The slump test was conducted following the BS EN 12350-2 to specify the procedure for evaluating the fresh concrete's workability. The apparatus used in this slump test were a cone, scale, and tamping rod.
Compression Test
The compression test was conducted to evaluate the strength of the concrete. Three (3) identical cubes from each designated mix of 100 mm size were selected to assess the strength. The evaluation was performed on days 3, 7, 14, and 28 (age of testing) using the BS EN 12390-3, 2002, as a reference. The samples tested are shown in Table 3.
Table 3: The Samples Tested for Compressive Strength
3. Result and Discussion
The study discovered that the workability of the POFA concrete decreased as the amount or percentage of POFA increased. In comparison, the compressive strength increased when its amount increased to 10%. Consequently, 5% of POFA exhibited the highest compressive strength and good workability. Good workability and high strength mean it is an ideal concrete mix for high-rise structures (Jagana & Vinod, 2017).
The following are the descriptions of the results.
Slump Test
The results of the slump tests are shown in Figure 1.
Mix Designation
Day
3 7 14 28
OPC 3 3 3 3
5POFA 3 3 3 3
10POFA 3 3 3 3
15POFA 3 3 3 3
Figure 1: The Results of Slump Tests of Four (4) Concrete Mixes with Different Amounts of POFA
Figure 1 shows the slump height of high-strength concrete (HSC) with various percentages of POFA as an additive to the cement. Here they are labelled 5POFA, 10POFA, and 15POFA. The figure shows that the OPC and the 5POFA have the highest flow, followed by those the 10POFA and 15POFA. It also indicates that the OPC and 5POFA have a collapsed slump with a 240 mm height, while 10POFA and 15POFA have a true slump with 20 mm and 0 mm heights, respectively.
The experiment also indicated that the workability of concrete decreased as the amount of POFA in the concrete increased. These results were consistent with Oyejobi D.O et al. (2015) 's findings which reported that the workability of the POFA concrete's slump test decreased as the POFA content increased. This condition can be explained that its workability decreases due to the existence of the POFA that contains a high volume of LOI, which absorbs more water, which in turn reduces the concrete workability (Alsubari et al., 2016). Lim et., (2013) explained that the irregular form and porous compositions of the POFA enable the absorption of more water which decreases the concrete workability.
Compressive Strength Test Results
The results of the compressive strength of four (4) series of concrete mixes are shown in Figure 2.
Figure 2: Compressive Strengths of the OPC, 5POFA, 10POFA, and 15POFA
Figure 2 shows the effect on the compressive strength of the OPC, 5POFA, 10POFA, and 15 POFA at all ages ranging from 3 to 28 days. On Day 3, the figure shows that the 5POFA obtains the highest compressive strength, marked 76.57 MPa, 17.8 percent higher than the OPC, with a reading of 62.92 MPa. The 10POFA, with a compressive strength of 72.57 MPa, shows 13.3 percent higher than the OPC, while the 15POFA has the lowest compressive strength compared to all mixes, with a reading of 71.12 MPa.
240 240
20 0
OPC 5POFA 10POFA 15POFA
Slump Height (mm) 62.92 73.03 73.88 80.32
76.57 78.38 80.43 84.12
72.57 72.78 74.22 81.89
71.12 78.75 73.56 79.095
0 10 20 30 40 50 60 70 80 90
DAY 3 DAY 7 DAY 14 DAY 28
Compressive Strength (MPa)
OPC 5POFA 10POFA 15POFA
On Day 7, 10POFA with a compressive strength of 72.78 MPa is the lowest. However, the strength of the 5POFA and 15POFA experienced a 6.8 percent and 7.3 percent increase in MPa compared to that of the OPC. In contrast, the 15POFA has the highest compressive strength, 78.75 MPa.
On Day 14, 15POFA showed the lowest compressive strength with a reading of 73.56 MPa, whereas the 5POFA and 10POFA marked 80.43 MPa and 74.22 MPa, indicating an increment with 8.1 percent and 0.46 percent, respectively, compared to OPC. The 5POFA's strength once again outperforms the rest of the mixes. However, the 10POFA and 15POFA seem to show a similar pattern, and both have slightly identical strengths.
On the 28th day, the figure shows that the 5POFA attains a higher compressive strength, marked 84.12 MPa, compared to the OPC, with 80.32 MPa. The 10POFA and 15POFA follow it, recording 81.89 MPa and 79.095 MPa, respectively. It can be seen that the strength has developed as 5% of POFA is used as addictive to the cement in the concrete. It appears that a higher age produces a higher compressive strength. Hence, among the four (4) series of concrete mixes conducted in the experiment, the 5% POFA as the cement additive improved the compressive strength of the concrete at all ages studied (up to 28 days). This improvement was due to the formation of the CSH gel, which developed consistently compared to the other mixes.
In conclusion, the 5POFA appeared to be the most effective mix in strength development, followed by the 10POFA, OPC and 15POFA. It is noted that the increment in the compressive strength may have been attributed to pozzolanic activity (Safiuddin et al., 2011). Similarly, in this experiment, the compressive strength decreased as the POFA addition to the cement increased to 10%. It demonstrated that a higher proportion of the POFA as an additive to cement had reduced the compressive strength. Note that the high porosity of the POFA particles decreases the cement's compressive strength. Hence increasing the water/binder (w/b) ratio in the concrete produces a lower compressive strength (Safiuddin et al., 2011). This is due to the properties of the porous POFA particles affecting water absorption.
Relationship of the Slump and Compressive Strength of Concrete
Figure 3 shows the relationship between the slump test and compression test of the OPC, 5POFA, 10POFA and 15POFA.
Figure 3: Relationship between the Slump and Compression Tests of the OPC, 5POFA, 10POFA and 15 POFA
Figure 3 shows both the workability and compressive strength in a graph. The relationship between the slump test and compression test is identified to analyze the quality of the concrete mix. The figure shows the 10POFA and 5POFA having the lowest workability while the strength of the 15POFA and OPC is the lowest in 28 days. The 5POFA, on the other hand, tends to have the highest workability and compressive strength on Day 28. Since the goal of this study was to obtain the highest strength and workability, the highest property of the concrete mix exhibited in Figure 3 is the 5POFA.
4. Conclusions
This study attempted to discover the workability and strength of concrete incorporated with the POFA as an additive to cement through experimental investigation. Based on the experiments conducted, the findings are as follows:
1) The utilization of POFA as additive cement in concrete shows reduced workability up to 5% addictive. This is due to the porous nature of POFA, which can absorb more water than cement. Here it shows that the higher the percentage of POFA incorporated in the concrete, the lower its workability.
2) Using a certain amount of the POFA as an additive to cement in concrete improves its compressive strength. However, as the percentage of addition POFA increases, the compressive strength is reduced. Thus, this study concluded that 5% of POFA is the optimum percentage used as additive cement to produce the best compressive strength concrete.
In conclusion, concrete with a POFA addictive of more than 5% to cement produces a strength similar to the control concrete but lacks workability. However, all mixes produced in this study can be utilized depending on their application. The control concrete can be used if more workable and minimal strength is required. If a workable and high strength is needed, the 5POFA is the one.
On the other hand, if less workable and comparable strength to the control concrete is required, the 10POFA and 15POFA concrete mixes can be utilized instead.
-50 0 50 100 150 200 250 300
0 10 20 30 40 50 60 70 80 90
OPC 5POFA 10POFA 15POFA
Slump Height (mm)
DAY 3 DAY 7 DAY 14 DAY 28 SLUMP TEST
Acknowledgments
We acknowledge the Universiti Teknologi Mara (UiTM) for the financial support granted under 600-RMC/GIP 5/3 (032/2021). In addition, the authors wish to extend special thanks to the Institute for Infrastructure Engineering and Sustainable Management (IIESM) and the Faculty of Civil Engineering, Universiti Teknologi Mara (UiTM), for providing the facilities for laboratory work.
References
Alsubari, B., Shafigh, P., & Jumaat, M. Z. (2016). Utilization of high-volume treated palm oil fuel ash to produce sustainable self-compacting concrete. Journal of Cleaner Production, 137, 982–996. https://doi.org/10.1016/j.jclepro.2016.07.133
Altwair, N. M., & Kabir, S. (2010). Palm Oil Fuel Ash( POFA ): An Environmental-Friendly Supplemental Cementitious Material For Concrete Production. International RILEM Conference on Material Science, III(January 2010), 113–126.
Hamada, H. M., Jokhio, G. A., Yahaya, F. M., Humada, A. M., & Gul, Y. (2018). The present state of the use of palm oil fuel ash (POFA) in concrete. Construction and Building Materials, 175, 26–40. https://doi.org/10.1016/j.conbuildmat.2018.03.227
Iskandar, M. J., Baharum, A., Anuar, F. H., & Othaman, R. (2018). Palm oil industry in South East Asia and the effluent treatment technology—A review. Environmental Technology and Innovation, 9(May 2017), 169–185. https://doi.org/10.1016/j.eti.2017.11.003
Islam, M. M. U., Mo, K. H., Alengaram, U. J., & Jumaat, M. Z. (2015). Mechanical and fresh properties of sustainable oil palm shell lightweight concrete incorporating palm oil fuel ash.
Journal of Cleaner Production, 115, 307–314. https://doi.org/10.1016/j.jclepro.2015.12.051 Ismail, M. A., Budiea, A. M. A., Hussin, M. W., & Muthusamy, K. B. (2010). Effect of POFA
fineness on durability of high strength concrete. Indian Concrete Journal, 84(11), 21–28.
Jagana, R., & Vinod, C. V. (2017). High Strength Concrete. International Journal of Engineering Science & Research Technology, 6(3), 207–209.
MPOB. (2018). Oil Palm Planted Area 2018.
http://bepi.mpob.gov.my/images/area/2018/Area_summary.pdf
Munir, A., Abdullah, Huzaim, Sofyan, Irfandi, & Safwan. (2015). Utilization of palm oil fuel ash (POFA) in producing lightweight foamed concrete for non-structural building material.
Procedia Engineering, 125(December), 739–746.
https://doi.org/10.1016/j.proeng.2015.11.119
Nagaratnam, B. H., Rahman, M. E., Mirasa, A. K., Mannan, M. A., & Lame, S. O. (2016).
Workability and heat of hydration of self-compacting concrete incorporating agro-industrial
waste. Journal of Cleaner Production, 112, 882–894.
https://doi.org/10.1016/j.jclepro.2015.05.112
Oyejobi D.O, Abdulkadir T.S., & Ahmed A.T. (2015). A Study of Partial Replacement of Cement with Palm Oil Fuel Ash in Concrete Production. Journal of Agricultural Technology, 12(4), 619–631. https://doi.org/10.5281/zenodo.192492
Safiuddin, M., Salam, M. A., & Jumaat, M. Z. (2011). Utilization of palm oil fuel ash : A review.
Journal of Civil Engineering and Management, 17(2), 234–247.
https://doi.org/10.3846/13923730.2011.574450
Sata, V., Jaturapitakkul, C., & Kiattikomol, K. (2004). Utilization of Palm Oil Fuel Ash in High- Strength Concrete. Journal of Materials in Civil Engineering, 16(6), 623–628.
https://doi.org/10.1061/(ASCE)0899-1561(2004)16:6(623)
Tay, J. (1990). Ash from Oil-Palm Waste as Concrete Material. 2(2), 94–105.
Tonnayopas, D., Nilrat, F., Putto, K., & Tantiwitayawanich, J. (2016). Effect of Oil Palm Fiber Fuel Ash on Compressive Strength of Hardening Concrete. 1–3.
Zeyad, A. M., Megat Johari, M. A., Tayeh, B. A., & Yusuf, M. O. (2017). Pozzolanic reactivity of ultrafine palm oil fuel ash waste on strength and durability performances of high strength concrete. Journal of Cleaner Production, 144(October 2017), 511–522.
https://doi.org/10.1016/j.jclepro.2016.12.121
