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Fermented Banana Stem Extract as a Sustainable Water-Reducing Admixture in Concrete2Jaypee University of Information Technology, Waknaghat, Solan, India
Gokarna Awasthi1,2, Shankar Bhujel1, Tika Sagar Adhikari1, Saurav Gautam1, Samiksha Ghising1, Samika Sunuwar1, Kaushal Kumar2*
1 Madan Bhandari College of Engineering, Urlabari-03, Morang, Nepal
Corresponding Author: kaushalkumar4048@gmail.com
ABSTRACT
This study explores the utilization of Fermented Banana Stem (FBS) extract as a sustainable bio-based water-reducing admixture in concrete. The FBS extract was prepared by collecting fresh banana stems, cleaning, chopping, and mixing them with water in a 1:1 ratio by weight. The mixture was then fermented naturally at room temperature for seven days, followed by filtration to obtain brownish, mildly fermented liquid rich in organic compounds. Physical characterization revealed a viscous texture and earthy odor, while chemical analysis confirmed the presence of phenolic compounds, polysaccharides, and organic acids, which are known to enhance workability, strength, and durability in cementitious systems.
In the experimental phase, FBS extract was used to partially replace mixing water at 0%, 5%, 10%, 15%, 20%, and 25% proportions for an M20 grade Concrete. Standard tests were conducted to evaluate the workability (slump test), compressive strength (after 7 and 28 days of curing), and durability (water absorption test) of the prepared concrete mixes. Results indicated that FBS addition significantly improved workability, The slump increased from 75 mm to 112 mm. The maximum compressive strength of 30.25 MPa was observed at 15% replacement, attributed to improved particle dispersion and enhanced hydration due to the organic compounds present in the extract. Beyond 20% replacement, a slight reduction in strength was recorded, suggesting an oversaturation effect. Moreover, water absorption decreased consistently with increasing FBS content, confirming improved pore structure and reduced permeability.
In conclusion, Fermented Banana Stem extract can serve as an effective and eco-friendly admixture in concrete production. An optimum dosage of 15% replacement of mixing water enhances workability, compressive strength, and durability, promoting sustainable and green construction practices.
Keywords:
FBS extract
Bio-based Admixture
Workability
Compressive Strength
Water Absorption
Sustainable Concrete
1. Introduction
Concrete is the second most widely used construction material in the world after water, forming the backbone of infrastructure such as buildings, bridges, roads, and dams (Gagg 2014). Its global consumption is driven by its versatility, durability, and relative affordability, making it indispensable in urbanization and development projects (Schneider 2019). However, the increasing demand for high-performance concrete has led to greater dependence on chemical admixtures, such as plasticizers, superplasticizers, and accelerators, which, while improving workability and early strength, often contain synthetic and petroleum-based compounds (Mohamad et al. 2022a). These chemicals can leach toxic substances, rely on non-renewable resources, and in some cases, accelerate corrosion of steel reinforcement, thereby compromising long-term durability (Mohamad et al. 2022b). Such environmental and durability concerns have prompted the search for sustainable, bio-based alternatives in concrete technology (Cheung et al. 2017).
In response, research has increasingly focused on bio-based and agro-waste–derived materials as eco-friendly substitutes for conventional admixtures. Agricultural residues, which are often discarded, provide a low-cost and sustainable resource for concrete modification. Among these, banana plant residues including leaves, stems, and peels are particularly promising (Akinyemi and Dai 2020, Zaini et al. 2023, Patil et al. 2024a). In Nepal, banana cultivation produces substantial waste, with stems alone accounting for around 60% of the plant biomass (Pandit et al. 2020b) most of which remains unused. Recent studies have highlighted the potential of banana-based derivatives: banana leaf ash (10% replacement) enhances 28-day compressive strength by 12.6% (Bhutto et al. 2024), banana stem fibers (0.5% volume) increase tensile strength by 7.7% (Pal et al. 2023c), and and banana stem juice (5% dosage) improves workability and early-age strength (Dadzie et al. 2024).
Despite these advances, the use of Fermented Banana Stem (FBS) extract as a liquid admixture remains largely unexplored. Fermentation, typically carried out for seven days (Pradeep et al. 2022), can release bioactive compounds such as polysaccharides, organic acids, and natural enzymes, which may act as natural plasticizers, accelerate cement hydration, reduce water demand, and enhance durability (Carvalho and Conte-Junior 2023, Hashim et al. 2024, Roselli et al. 2024, Wani and Dhanya 2025). Exploring FBS extract in concrete is especially relevant for Nepal, where abundant banana waste offers a locally available, low-cost alternative to imported chemical admixtures. By valorizing agricultural residues, this approach reduces environmental impact, improves mechanical and durability properties, and promotes sustainable construction practices aligned with global efforts to lower carbon emissions and dependence on synthetic chemicals. This study therefore addresses both global sustainability challenges and context-specific opportunities in Nepal, proposing a pathway for eco-friendly, cost-effective, and resource-efficient concrete solutions.
Chemical admixtures such as sulphonated melamine formaldehyde condensate (SMFC) are associated with high leaching of toxic compounds like formaldehyde (J M Dransfield 2007), which can contaminate water sources and pose environmental hazards (Mohamad et al. 2021, Ochs & Müder 1996). Moreover, polymer-based and oil-derived admixtures, being non-renewable, contribute to pollution through persistent chemical residues (Togerö 2006a, Togerö 2007b). Calcium chloride–based admixtures further accelerate corrosion of reinforcing steel, thereby compromising structural durability (Cheung et al. 2018a, Al Rawashdeh et al. 2021b, Lai et al. 2023c). Additionally, conventional water-reducing admixtures, though beneficial for workability and strength, require energy-intensive manufacturing processes that emit significant CO₂ (Schiefer and Plank 2023)
These challenges are particularly critical for developing regions like Nepal, which depend on imported patented chemical formulations, increasing both cost and environmental footprint. Although several plant-based alternatives (e.g., cypress extract) have shown promise due to their organic polysaccharide content (Onjure et al. 2023, Deore et al. 2024, Woldemariam et al. (2014), locally available agricultural wastes such as banana stems remain underexplored. This research aims to investigate Fermented Banana Stem extract (FBS) as a potential bio-admixture that simultaneously addresses waste valorization and sustainable concrete production in the Nepalese context.
2. Materials and Methods
In this study, thirty-six concrete cubes of size 150 mm × 150 mm × 150 mm were cast with partial replacement of mixing water by Fermented Banana Stem extract at 0%, 5%, 10%, 15%, 20%, and 25%. All specimens were cured for 28 days under standard laboratory conditions. The fresh concrete’s workability was assessed using the slump test, while compressive strength and water absorption tests were performed to evaluate hardened properties. The obtained results were analyzed to determine the influence of FBS extract content on the performance of concrete.
2.2 Materials
The experiment used 43-grade OPC cement, natural fine and coarse aggregates, and FBS extract prepared over seven days. Cement and aggregates were tested as per IS standards for mix design suitability. A seven-day fermentation period for FBS was chosen based on literature, as it is commonly reported as appropriate for similar materials.
2.2.1 Cement
43-grade Ordinary Portland Cement (OPC) was used (Fig. 1). Its properties fineness, standard consistency, initial and final setting times, and specific gravity were tested as per IS 4031 and are summarized in Table 1.
Test | Observed Value | IS Standard Requirement (IS 4031, Parts 1–15) |
|---|---|---|
Fineness (% retained on 90 µm sieve) | 7% | ≤ 10% |
Standard Consistency (%) | 30% | 26–33% |
Initial Setting Time (minutes) | 32 | ≥ 30 |
Final Setting Time (minutes) | 260 | ≤ 600 |
Specific Gravity | 3.13 | 3.10–3.15 |
2.2.2 Fine Aggregate
Fine aggregate, comprising natural sand particles smaller than 4.75 mm, was used in this study. The sample of fine aggregate is shown in Fig. 2, and its properties were determined through specific gravity, water absorption, and fineness modulus tests, all conducted as per relevant IS: 2386 and IS: 383. The results of these tests are presented in Table 2.
Test | Observed Value | IS Standard Requirement IS: 2386 and IS: 383. |
|---|---|---|
Specific Gravity | 2.63 | 2.60–2.70 |
Water Absorption (%) | 1.2 | ≤ 2.0 |
Fineness Modulus | 2.75 | 2.3–3.1 (Zone II as per IS: 383) |
2.2.3 Coarse Aggregate
Coarse aggregate, consisting of particles retained on a 4.75 mm sieve, was used in this study. The sample of coarse aggregate is shown in Fig. 3, and its properties were determined through specific gravity, water absorption, impact value, and Los Angeles abrasion tests, all conducted as per IS 2386 (Part 3). The results of these tests are presented in Table 3.
Test | Observed Value | IS Standard Requirement IS 2386 (Part 3) | |||
|---|---|---|---|---|---|
Specific Gravity | 2.5 | 2.50–2.90 | |||
Water Absorption (%) | 0.8 | ≤ 2.0 | |||
Aggregate Impact Value (%) | 18.2 | ≤ 30 | |||
Los Angeles Abrasion Value (%) | 22.02 | ≤ 30 | |||
 |  |  | |||
A Figure 1: 43-grade OPC Cement | A Figure 2: Fine Aggregate | A Figure 3: Coarse Aggregate | |||
2.2.4 Water
Potable water with a pH value of 7.5 was used for all mixing and curing purposes.
2.2.5 FBS Extract as a Water-Reducing Admixture
Fermented Banana Stem (FBS) extract was used as a natural water-reducing admixture in concrete. Its organic compounds, such as polysaccharides and phenolics, help improve workability, enhance hydration, and contribute to durability. The extract was prepared by collecting fresh banana stems locally, peeling and thoroughly washing them to remove dirt and sap (Fig. 4 and Fig. 5). The cleaned stems were chopped (Fig. 6) into small pieces and mixed with water in a 1:1 weight ratio (Fig. 7) to ensure proper fermentation. The mixture was placed in airtight containers and fermented naturally at room temperature for seven days in a dark, dry environment. After fermentation, the mixture was filtered to remove solid residues (Fig. 8), and the resulting extract was stored in clean, airtight containers for use as a partial replacement of mixing water in concrete (Fig. 9).
 |  |  |
|---|---|---|
A Figure 4: Collection of Fresh Banana Stems | A Figure 5: Peeling and Washing of Banana Stems | A Figure 6: Chopping and Preparation of Stems |
 |  |  |
A Figure 7: Mixing and Natural Fermentation | A Figure 8: Filtration to Remove Solid Residues | A Figure 9: Storage of Final FBS Admixture |
The physical properties of the FBS extract included a brownish to dark brown color, a mildly earthy and slightly sweet odor, a slightly astringent taste, and a viscous appearance (Table 4). Chemical analysis and literature review indicate that FBS extract contains phenolic compounds, polysaccharides, organic acids, and natural enzymes, which improve concrete performance by enhancing workability, accelerating hydration, and increasing durability (Zou et al. 2022) The components and their functions are summarized in Table 4.
Component | Function in Concrete Enhancement |
|---|---|
Phenolic Compounds | Act as antioxidants and improve durability by reducing oxidation-induced degradation (Pradipta et al. 2019) |
Polysaccharides | Enhance binding, improve workability, and contribute to internal curing. (Isik and Ozkul 2014) |
Organic Acids & Enzymes | Accelerate hydration and enhance early strength development Huang et al. (2022) |
2.3 Mix Design and Estimation of Materials
The mix design for M-20 grade concrete was prepared as per IS 10262:2019, ensuring the desired strength and durability. The proportion obtained was 1: 1.93: 3.17 (C: FA: CA). Material quantities were accurately calculated to maintain proper batching and minimize wastage. This standardized mix design helps achieve consistent quality and enables reliable evaluation of the effect of FBS extract on the concrete’s fresh and hardened properties.
2.3 Specimen Preparation and Nomenclature of Specimen
Concrete was mixed manually to ensure uniform blending of cement, aggregates, water, and FBS extract as a partial replacement for mixing water (Fig. 10 and Fig. 11). The internal surfaces of 150 mm cube moulds were coated with a thin layer of lubricant to facilitate demoulding. The concrete was cast in three layers per cube, with each layer compacted manually using 25–30 blows of a tamping rod (Fig. 12). After 24 hours, the cubes were carefully demolded (Fig. 13) and immediately transferred for curing (Fig. 14). The specimens were submerged in a tank of clean water at ambient temperature and cured for 28 days, after which they were removed for testing (Fig. 15). Compressive strength and other tests were conducted at 7 and 28 days to evaluate the effect of FBS extract on early and standard-age concrete performance.
Concrete specimens were prepared with FBS extract replacing mixing water at 0%, 5%, 10%, 15%, 20%, and 25%. For each replacement level, six cubes were cast, with three specimens tested at 7 days and three at 28 days to ensure reliable results. Samples were labeled “A” followed by the FBS percentage (e.g., A5) for clear identification, totaling 36 specimens. The nomenclature of specimens is shown in Table 5.
 |  |  |
|---|---|---|
A Figure 10: Preparation of Dry Concrete Mix | A Figure 11: Adding Water/FBS Admixture | A Figure 12: Casting/Molding of Concrete Cube |
 |  |  |
A Figure 13: Demolding/Extraction of Concrete Cubes | A Figure 14: Curing of Concrete Cubes | A Figure 15: Concrete Cube Post-Water Curing |
Nomenclature of Specimen | Replacement percentage of FBS | Number of Samples for 7 Days | Number of Samples for 28 Days |
|---|---|---|---|
A0 | 0 | 3 | 3 |
A5 | 5 | 3 | 3 |
A10 | 10 | 3 | 3 |
A15 | 15 | 3 | 3 |
A20 | 20 | 3 | 3 |
A25 | 25 | 3 | 3 |
Total | 18 | 18 | |
2.4 Testing Methods
2.4.1 Workability Test (Slump)
Workability was measured using the slump test as per IS 1199:1959. Concrete was filled in three layers in a standard slump cone (Fig. 16) of 100 mm top, 200 mm bottom, and 300 mm height, each tamped 25 times. The vertical slump was then recorded (Fig. 17).
 |  |
|---|---|
A Figure 16: Geometric Specifications of the Slump Cone | A Figure 17: Measuring the Slump of Fresh Concrete |
2.4.2 Compressive Strength Test
Compressive strength of 150 mm cubes was determined following IS 516:1957. The maximum stress at failure was recorded, and compressive strength was computed using the formula (Fig. 18, Fig. 19):
CompressiveStrength=
 |  |
|---|---|
A Figure 18: Schematic of Compression Testing Machine (CTM) | A Figure 19: Concrete Cube Under Compression Testing Machine (CTM) |
2.4.3 Water Absorption Test
Water absorption was determined according to IS 1199:1959. Oven-dried cubes (100–110°C, 24 h) were weighed (W1), then immersed in water for 24 hr and weighed again (W2). Water absorption (%) was calculated as:
Water Absorption (%)=
× 100%
Where W1 = oven-dry weight and W2 = saturated weight.
3. Results and Discussion
From this experiment, the obtained data are systematically analyzed and discussed. The results are presented with appropriate tables and graphical representations to illustrate the effects of varying FBS extract content on concrete properties, including workability, compressive strength, and water absorption.
3.1 Workability
The slump test results show a clear improvement in workability with increasing FBS extract. The control mix (A0) had a slump of 75 mm, which increased to 85, 95, 105, 110, and 112 mm for 5%, 10%, 15%, 20%, and 25% FBS replacement, respectively (Table 6, Fig. 20). The most significant improvement was observed up to 20%, beyond which the effect slightly plateaued.
Fig. 20
Slump Values with Varying Proportion (0%,5%,10%,15%,20%,25%) of FBS Extracts
This enhancement can be attributed to the chemical nature of FBS extract, which contains polysaccharides, phenolic compounds, and organic acids. These compounds likely act as natural plasticizers, dispersing cement particles and reducing internal friction, thereby improving flow. The plateau at higher dosages may result from saturation, where additional FBS does not further reduce friction. These explanations are consistent with prior studies on bio-based admixtures, indicating that organic compounds in agro-waste can effectively enhance concrete workability (Dadzie et al. 2024b)
3.2 Compressive Strength
The compressive strength of concrete improved with the addition of FBS extract up to 15% replacement and decreased at higher dosages (Table 6, Fig. 21). At 7 days, the control mix (A0) showed a strength of 15.60 MPa, which increased gradually to 15.78 MPa (A5), 16.80 MPa (A10), and reached a maximum of 30.25 MPa (A15). Beyond 15% replacement, the 7-day strength dropped to 16.03 MPa (A20) and 15.00 MPa (A25), while 28-day strength decreased slightly to 28.51 MPa and 25.72 MPa, respectively.
Fig. 21
Graphical Representation of Compressive Strength with Varying Proportion (0%,5%,10%,15%,20%,25%) of FBS Extracts
The increase in strength up to 15% FBS can be attributed to the chemical composition of the extract, including polysaccharides, phenolic compounds, and organic acids. These compounds improve particle dispersion, reduce water demand, and enhance hydration, leading to a denser and stronger concrete matrix. The decline in strength beyond 15% is likely due to oversaturation, where excess FBS interferes with cement hydration and reduces bonding efficiency.
3.2 Water Absorption
The water absorption of concrete decreased steadily with increasing FBS extract (Table 6, Fig. 22). The control mix (A0) had 0.6% absorption, which reduced to 0.55% (A5), 0.5% (A10), 0.45% (A15), 0.4% (A20), and 0.38% (A25), showing a maximum reduction of 37% at 25% replacement.
This improvement can be attributed to the bioactive compounds in FBS, such as polysaccharides and phenolic acids, which help fill micro-voids in the cement matrix, leading to a denser and more compact structure. Reduced porosity decreases water penetration, enhancing the durability of concrete.
These results indicate that FBS extract not only improves workability and strength but also contributes to better resistance against permeability-related issues.
Fig. 22
Water Absorption values with Varying Proportion (0%,5%,10%,15%,20%,25%) of FBS Extracts
Nomenclature of Specimen | Slump Test Result | Compressive Strength Result | Water Absorption Result | |
|---|---|---|---|---|
7-day's strength (MPa) | 28-day's strength (MPa) | |||
A0 | 75 | 15.60 | 26.02 | 0.6 |
A5 | 85 | 15.78 | 26.98 | 0.55 |
A10 | 95 | 16.80 | 28.32 | 0.5 |
A15 | 105 | 18.02 | 30.25 | 0.45 |
A20 | 110 | 16.03 | 28.51 | 0.4 |
A25 | 112 | 15.00 | 25.72 | 0.38 |
4. Conclusion
This study investigated the use of Fermented Banana Stem (FBS) extract as a sustainable, bio-based water-reducing admixture in M-20 concrete. The following conclusions can be drawn from the experimental results:
a)
Workability improved consistently with increasing FBS content, reaching a maximum effect at 20–25% replacement, due to the natural plasticizing action of polysaccharides and organic acids in the extract.
b)
Compressive Strength increased with FBS addition up to 15% replacement, achieving a maximum 28-day strength of 30.25 MPa. Beyond 15%, strength slightly decreased, likely due to oversaturation affecting cement hydration.
c)
Water Absorption decreased steadily with higher FBS content, demonstrating improved durability and a denser concrete matrix with reduced porosity.
d)
Overall, an optimum FBS replacement of 15% is recommended to enhance workability, strength, and durability while promoting sustainable and eco-friendly concrete practices.
The findings suggest that FBS extract is an effective natural admixture that can partially replace mixing water, offering a cost-effective and environmentally friendly alternative to conventional chemical admixtures.
A
Author Contribution
G.A. conducted the experiments, collected data, and drafted the initial manuscript. S.B. and T.S.A. assisted in specimen preparation, testing, and data organization. S.G., S.Gh., and S.S. contributed to laboratory work, data compilation, and preparation of figures and tables. K.K. supervised the research, validated the results, and finalized the manuscript. All authors reviewed the manuscript.
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Funding
The authors received no financial support from any organization or funding agency for the research, authorship, and/or publication of this article.
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Data Availability
The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.
Declarations
Ethics approval and consent to participate
This study did not involve any human participants or animal experiments. Therefore, ethical approval was not required.
Consent for publication
All authors have read and approved the final version of this manuscript and consent to its publication in the journal.
Competing interests
The authors declare no competing interests. Not applicable.
Conflicts of Interest
The authors declare that there is no conflict of interest regarding the publication of this paper.
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