PSI - Issue 70

Kavitha E. et al. / Procedia Structural Integrity 70 (2025) 588–595

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28 days. The addition of neem fibre above 0.5% which exhibits decreased strength in both NaOH concentration. The reduction in strength were observed when fibre content is increased is due to decrease in interfacial bond between fibre and mortar, the mix is stiff and it made difficult to compact it results in increase the porosity and fibre dispersion in the mortar (Navid and Mingzhong et al 2020). Test outcomes on flexural and bond strength of Various GP mortar specimens are illustrated in Fig.5. FS of GP neem fibre mortar specimens ranged from 4.5 N/mm 2 to 5.2 N/mm 2 for 10M and 4.7 N/mm 2 to 5.9 N/mm 2 for 12M respectively. FS improves significantly up to 0.5% neem fibre, with greatest values seen in M2-10M for 5.2 N/mm² and M2-12M for 5.9 N/mm². This is mostly due to the fracture-bridging effect of fibres, which improves the mortar's flexural strength and slows crack development (Sreevidya et al 2014; Kumar& Patil 2019). However, beyond 0.5% fibre concentration, fibre cluster formation causes incorrect dispersion within the matrix, limiting load distribution effectiveness and, as a result, flexural strength (Mahmood et al 2021). The addition of neem fibre improves fracture bridging, flexural toughness, and resistivity. However, high fibre content might cause fibre aggregation, resulting in localized weaknesses. The BS of geopolymer mortar improves with the addition of neem fibre up to 0.5%, after which it declines. M2-10M and M2-12M have the strongest BS of 2.42 N/mm² and 2.60 N/mm², respectively. This improvement is due to the increased interfacial adhesion provided by neem fibre, which improves the bond between the mortar and the substrate. However, at higher fibre dosages (0.75% and 1%), bond strength reduces due to fibre clustering, resulting in poor interfacial bonding and lower load transfer efficiency (Ranjith & Easwaran, 2019) 3. Conclusion Based on the investigation the following inferences were drawn; This study investigates the effect of neem fibre on the workability, compressive strength, flexural strength, and bond strength of geopolymer mortar. The results demonstrate that the addition of neem fibre decreases workability. This is because the mix becomes less flowable as a result of increased water absorption and fibre tangling. Fibre inclusion improves compressive strength by up to 0.5%, as fibres aid in crack control and load distribution. However, extra fibres above 0.5% induce clustering, which reduces strength. Fibre insertion also increases flexural and bond strength by improving crack resistance and adhesion. However, at higher doses, inadequate fibre dispersion decreases the benefits. The optimal dose of neem fibre is 0.5%, which balances increased strength with appropriate workability. The investigation indicated that elevated molarity augmented strength characteristics, whereas neem fibre enhanced durability and crack resistance. These findings emphasized the potential of geopolymer mortar as a sustainable alternative to traditional cement-based structures. Acknowledgements The authors wish to state that there are no acknowledgements for this work. Abdullah, S., Ming, L., Abdullah, M. M. A. B., Yong, H., Zulkifly, K., Kamarudin, H., 2018. Effect of Alkali Concentration on Fly Ash Geopolymers. IOP Conference Series: Materials Science and Engineering 343, 012013. Ahmed, H.U., Mahmood, L.J., Muhammad, M.A., Faraj, R.H., Qaidi, S.M.A., Sor, N.H., Mohammed, A.S., Mohammed, A.A., 2022. Geopolymer concrete as a cleaner construction material: An overview on materials and structural performances 5,100111. Al-Mashhadani, M.M., Canpolat, O., Aygormez, Y., Uysal, M., Erdem, S., 2018. Mechanical and microstructural characterization of fibre reinforced fly ash-based geopolymer composites. Construction and Building Materials 167, 505 – 513. Alomayri, T., Low, I.M., 2013. Synthesis and characterization of mechanical properties in cotton fibre-reinforced geopolymer composites. Journal of Asian Ceramic Societies 1(1), 30 – 34. Ampol, W., Ronnakrit, K., Sakchai, N., Vanchai, S., Prinya, C., 2020. Natural fibre reinforced high calcium fly ash geopolymer mortar. Construction and Building Materials 241, 118143. Anvari, M., Toufigh, V., 2022. Experimental and probabilistic investigation on the durability of geopolymer concrete confined with fibre References