The Effect of Alkali Treatment Concentrations on the Mechanical Properties of Ronier Fiber Reinforced Concrete

Rosalie Umuhoza; Philip Mogire; Naftary Gathimba; Brian Odero

doi:10.48084/etasr.17374

Authors

Rosalie Umuhoza Department of Civil Engineering, Pan African University Institute for Basic Sciences, Technology, and Innovation (PAUSTI), Nairobi, Kenya
Philip Mogire Department of Building and Civil Engineering, Murang'a University of Technology, Murang'a, Kenya
Naftary Gathimba Department of Civil, Construction and Environmental Engineering, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
Brian Odero Department of Civil, Construction and Environmental Engineering, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya

Volume: 16 | Issue: 2 | Pages: 34102-34110 | April 2026 | https://doi.org/10.48084/etasr.17374

Received: 6 January 2026 | Revised: 1 February 2026 and 17 February 2026 | Accepted: 27 February 2026 | Online: 3 February 2026

Corresponding author: Rosalie Umuhoza

Abstract

This study experimentally investigates the effect of sodium hydroxide (NaOH) treatment on ronier fibers and their influence on the mechanical performance of concrete. With the growing demand for sustainable construction materials, natural fiber-reinforced concrete presents an attractive alternative to synthetic reinforcements. Ronier fibers, derived from the African Borassus aethiopum palm, possess high tensile strength, flexibility, and inherent alkali resistance, making them suitable for cementitious composites. In this study, fibers were treated with 1%, 3%, and 5% NaOH solutions and incorporated into concrete at a constant dosage of 1% by cement weight. Fiber tensile testing, Scanning Electron Microscopy (SEM), and Fourier Transform Infrared (FTIR) analyses were performed to assess the mechanical behavior, surface morphology, and chemical modifications prior to incorporation. Concrete mixes included a control, untreated fibers, and NaOH-treated fibers. Compressive, split tensile, and flexural strengths were evaluated at 7, 14, and 28 days using standard cube, cylinder, and beam specimens. The results showed that fiber inclusion caused a slight reduction in compressive strength, which increased with treatment concentration, whereas significant enhancements were observed in tensile and flexural performance. At 28 days, the split tensile strength increased by approximately 8% for untreated fibers and 19% for the 1% treated fibers, whereas the flexural strength improved by about 6% and 12.5%, respectively. Higher NaOH concentrations reduced the performance due to fiber degradation. Overall, the 1% NaOH treatment was identified as optimal, demonstrating the potential of ronier fiber-reinforced concrete for improved crack resistance and flexural capacity in sustainable and low-cost construction applications.

Keywords:

compressive strength, fiber-reinforced concrete, flexural strength, NaOH treatment, Ronier fibers, tensile strength

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References

M. Anas, M. Khan, H. Bilal, S. Jadoon, and M. N. Khan, "Fiber Reinforced Concrete: A Review," in The 12th International Civil Engineering Conference, Sept. 2022, vol. 22, no. 1, Art. no. 3.

S. Paul, G. Van Zijl, and B. Šavija, "Effect of Fibers on Durability of Concrete: A Practical Review," Materials, vol. 13, no. 20, Oct. 2020, Art. no. 4562.

A. Singh and B. P. Yadav, "Sustainable innovations and future prospects in construction material: a review on natural fiber-reinforced cement composites," Environmental Science and Pollution Research, vol. 31, no. 54, pp. 62549–62587, Oct. 2024.

C. R. Rusnak, "Sustainable Strategies for Concrete Infrastructure Preservation: A Comprehensive Review and Perspective," Infrastructures, vol. 10, no. 4, Apr. 2025, Art. no. 99.

H. Ahmad, G. Chhipi-Shrestha, K. Hewage, and R. Sadiq, "A Comprehensive Review on Construction Applications and Life Cycle Sustainability of Natural Fiber Biocomposites," Sustainability, vol. 14, no. 23, Nov. 2022, Art. no. 15905.

Z. F. Akbulut, T. A. Tawfik, P. Smarzewski, and S. Guler, "Advancing Hybrid Fiber-Reinforced Concrete: Performance, Crack Resistance Mechanism, and Future Innovations," Buildings, vol. 15, no. 8, Apr. 2025, Art. no. 1247.

W. F. Edris et al., "Examining Mechanical Property Differences in Concrete with Natural and Synthetic Fiber Additives," Journal of Composites Science, vol. 8, no. 5, Apr. 2024, Art. no. 167.

P. Sahu and M. Gupta, "A review on the properties of natural fibres and its bio-composites: Effect of alkali treatment," Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications, vol. 234, no. 1, pp. 198–217, Jan. 2020.

D. Thapliyal et al., "Natural Fibers Composites: Origin, Importance, Consumption Pattern, and Challenges," Journal of Composites Science, vol. 7, no. 12, Dec. 2023, Art. no. 506.

A. D. Gudayu, D. E. Getahun, D. M. Mekuriaw, F. T. Walelign, and A. S. Ahmed, "Natural fiber reinforced cementitious composites; materials, compatibility issues and future perspectives," Composite Interfaces, vol. 32, no. 3, pp. 363–397, Mar. 2025.

Z. Osman, M. Elamin, E. Ghorbel, and B. Charrier, "Influence of Alkaline Treatment and Fiber Morphology on the Mechanical, Physical, and Thermal Properties of Polypropylene and Polylactic Acid Biocomposites Reinforced with Kenaf, Bagasse, Hemp Fibers and Softwood," Polymers, vol. 17, no. 7, Mar. 2025, Art. no. 844.

D. Y T, J. Hindi, G. B M, and M. K, "Influence of alkali treatment in enhancing crystallinity and breaking force of pineapple leaf fiber," Scientific Reports, vol. 15, Oct. 2025, Art. no. 36081.

I. Shah, L. Jing, Z. M. Fei, Y. S. Yuan, M. U. Farooq, and N. Kanjana, "A Review on Chemical Modification by using Sodium Hydroxide (NaOH) to Investigate the Mechanical Properties of Sisal, Coir and Hemp Fiber Reinforced Concrete Composites," Journal of Natural Fibers, vol. 19, no. 13, pp. 5133–5151, Dec. 2022.

M. Varma and S. Chandran, "Surface treatment of natural fibers for enhancing interfacial adhesion and mechanical properties in biocomposites - a comprehensive review," Composite Interfaces, vol. 32, no. 12, pp. 1729–1765, Dec. 2025.

M. A. Saidi, A. Gorin, K. H. Soon, and E. Jayamani, "The optimum sodium hydroxide concentration for high strength pla-rice straw composites," Journal of Mechanical Engineering and Sciences, vol. 12, no. 1, pp. 3472–3478, Mar. 2018.

D. Bachtiar et al., "Effect of alkaline treatment on the thermal and mechanical properties of sugar palm fibre reinforced thermoplastic polyurethane composites," Scientific Reports, vol. 15, Apr. 2025, Art. no. 14085.

S. J. L.-M. Mandelot-Matetelot, P. Mogire, and B. Odero, "Performance Analysis of Ronier Fibers (Borassus Aethiopum) with Silica Fume on the Mechanical Properties of Concrete," Engineering, Technology & Applied Science Research, vol. 15, no. 1, pp. 20024–20033, Feb. 2025.

N. Kumar, A. Singh, K. Debnath, and N. Kumar, "Water Absorption and Mechanical Behaviour of Borassus Fruit Fibre-Reinforced Composites," Emerging Materials Research, vol. 9, no. 1, pp. 10–17, Mar. 2020.

A. A. Mahamat et al., "Decision Tree Regression vs. Gradient Boosting Regressor Models for the Prediction of Hygroscopic Properties of Borassus Fruit Fiber," Applied Sciences, vol. 14, no. 17, Aug. 2024, Art. no. 7540.

BS EN 1097: Tests for mechanical and physical properties of aggregates. British Standards Institution, 2023.

IS 2386-3: Methods of test for aggregates for concrete, Part 3: Specific gravity, density, voids, absorption and bulking. India: Bureau of Indian Standards, 1963.

ASTM C136/C136M-19: Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates. West Conshohocken, PA, USA: ASTM International, 2019.

KS EAS 18-1:2017 Cement-Part 1: Composition, specification and conformity criteria for common cements. Nairobi, Kenya: Kenya Bureau of Standards, 2017.

BS EN 1008:2002, Mixing water for concrete - Specification for sampling, testing and assessing the suitability of water, including water recovered from processes in the concrete industry, as mixing water for concrete. British Standards Institution, 2002.

D. Verma and K. L. Goh, "Effect of Mercerization/Alkali Surface Treatment of Natural Fibres and Their Utilization in Polymer Composites: Mechanical and Morphological Studies," Journal of Composites Science, vol. 5, no. 7, July 2021, Art. no. 175.

K. A. S.-C. Toumbou, C. Githuku, and M. Mwai, "Effect of Chemical Treatment of Kenaf Fibers on the Structural Performance of Reinforced Concrete Beam," International Journal of Civil Engineering, vol. 11, no. 5, pp. 108–121, May 2024.

J. Rout, S. S. Tripathy, S. K. Nayak., M. Misra, and A. K. Mohanty, "Scanning electron microscopy study of chemically modified coir fibers," Journal of Applied Polymer Science, vol. 79, no. 7, pp. 1169–1177, Feb. 2001.

T. Fiore and C. Pellerito, "Infrared Absorption Spectroscopy," in Spectroscopy for Materials Characterization, 1st ed., S. Agnello, Ed. Wiley, 2021, pp. 129–167.

BS EN 12390–Testing of hardened concrete. British Standards Institution, 2012.

BS EN 12390-3 Testing of hardened concrete. Compressive strength of test specimens. British Standards Institution, 2019.

BS EN 12390-6: Testing hardened concrete – Tensile splitting strength of concrete. British Standards Institution, 2021.

ASTM C78/C78M-21: Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading). West Conshohocken, PA, USA: ASTM International, 2021.

M. M. Kabir, H. Wang, K. T. Lau, and F. Cardona, "Tensile properties of chemically treated hemp fibres as reinforcement for composites," Composites Part B: Engineering, vol. 53, pp. 362–368, Oct. 2013.

D. Panesar, R. Leung, M. Sain, and S. Panthapulakkal, "The effect of sodium hydroxide surface treatment on the tensile strength and elastic modulus of cellulose nanofiber," in Sustainable and Nonconventional Construction Materials using Inorganic Bonded Fiber Composites, Elsevier, 2017, pp. 17–26.

H. Mohit and V. Arul Mozhi Selvan, "A comprehensive review on surface modification, structure interface and bonding mechanism of plant cellulose fiber reinforced polymer based composites," Composite Interfaces, vol. 25, no. 5–7, pp. 629–667, July 2018.

S. Kathiresan and O. Meenakshisundaram, "Effect of alkali treated and untreated cellulose fibers and human hair on FTIR and tensile properties for composite material applications," SN Applied Sciences, vol. 4, Mar. 2022, Art. no. 74.

Ş. Özlüsoylu, A. Can, and S. Ganguly, "Characterization of delignified woods modified with ε -caprolactone," Polymer Testing, vol. 154, Jan. 2026, Art. no. 109061.

V. Ganesan et al., "Mechanical and Structural Characterization of Curauá Fiber, Sugarcane Biochar, and Poly(Lactic Acid) Hybrid Green Composites for Sustainable Biomass Utilization," Sugar Tech, vol. 27, pp. 1925–1946, Dec. 2025.

S. R. Ferreira, F. D. A. Silva, P. R. L. Lima, and R. D. Toledo Filho, "Effect of fiber treatments on the sisal fiber properties and fiber–matrix bond in cement based systems," Construction and Building Materials, vol. 101, pp. 730–740, Dec. 2015.

S. Ajabshir and R. Gupta, "Effects of Pretreatment Methods and Physical Properties of Cellulose Fibers on Compatibility of Fiber-Cement Composites: A Review," in Smart & Sustainable Infrastructure: Building a Greener Tomorrow, vol. 48, N. Banthia, S. Soleimani-Dashtaki, and S. Mindess, Eds. Cham: Springer, 2024, pp. 253–264.

S. S. Abdulhussein, I. B. Johari, and N. M. Fawzi, "Mechanical Properties of Aerated-Polystyrene Concrete Reinforced by Polymer Fibers," Annales de Chimie - Science des Matériaux, vol. 48, no. 4, pp. 435–445, Aug. 2024.

S. S. Abdulhussein, E. K. Jaafar, and N. M. Fawzi, "Impact of temperatures on the mechanical characteristics of modified reactive powder concrete," presented at the The International Scientific Conference of Engineering Sciences and Advanced Technologies, 2024, Art. no. 030004.

D. Lilargem Rocha, L. Tambara Júnior, M. Marvila, E. Pereira, D. Souza, and A. De Azevedo, "A Review of the Use of Natural Fibers in Cement Composites: Concepts, Applications and Brazilian History," Polymers, vol. 14, no. 10, May 2022, Art. no. 2043.

M. Z. Ul Haq et al., "Mechanical and Durability Performance of Sisal, Jute, and Hemp Fiber-Reinforced Concrete: Effects of Chemical Treatment and Fiber Geometry," Journal of Natural Fibers, vol. 22, no. 1, Dec. 2025, Art. no. 2583855.

S. Bashir et al., "Herbicide-induced alterations in hemp fiber: A comparative analysis of strength and morphology," Journal of Engineered Fibers and Fabrics, vol. 20, Jan. 2025.

M. Z. Khan, S. K. Srivastava, and M. Gupta, "Tensile and flexural properties of natural fiber reinforced polymer composites: A review," Journal of Reinforced Plastics and Composites, vol. 37, no. 24, pp. 1435–1455, Dec. 2018.