Issue 78

C. S. Karadumpa et alii, Fracture and Structural Integrity, 78 (2026) 146-167; DOI: 10.3221/IGF-ESIS.78.09

 Nano-modification accelerated 7-day compressive strength by 69-77% (21.13-22.06 MPa vs 12.5 MPa control), compensating slower GGBS/Fly Ash reactions and enabling rapid construction timelines while meeting final design strengths.  Among the investigated mixtures, GO primarily contributed to matrix refinement and compressive strength enhancement, whereas CNTs were more effective in improving tensile and flexural performance. The hybrid mixture incorporating 0.03% GO and 0.1% CNT provided the most balanced overall performance in terms of workability, mechanical properties, and microstructural characteristics and is therefore recommended as the optimum formulation evaluated in this study.  Microstructural analyses provided evidence consistent with the proposed mechanisms: GO densifies C-S-H, refines ITZ, promotes pozzolanic reactions; Excessive dosages (GO 0.05%, CNT 0.2-0.3%) cause agglomeration defects confirming proper dispersion outweighs quantity.  A 39.2% reduction in estimated CO ₂ emissions (246 vs 405 kg/m³) and a 50.7% carbon intensity improvement (7.13 vs 14.46 kg CO ₂ /MPa) through 8.8% cement reduction and 40-50% SCMs utilization. The results demonstrate the potential of hybrid nano-modified composite cement concrete as a sustainable alternative for structural applications. R EFERENCES [1] Andrew, R.M. (2018). Global CO ₂ emissions from cement production, 1928–2018. Earth System Science Data 10(4), pp. 195–217. DOI: https://doi.org/10.5194/essd-10-195-2018. [2] International Energy Agency (IEA), 2020. Global Status Report for Buildings and Construction 2020. IEA Publications, Paris. [3] Babu, K.G., Kumar, V.S.R. (2000). Efficiency of GGBS in concrete. Cement and Concrete Research 30(7), 1031–1036. DOI: https://doi.org/10.1016/S0008-8846(00)00271-4. [4] Malhotra, V.M., Mehta, P.K. (2002). High-Performance, High-Volume Fly Ash Concrete. Supplementary Cementing Materials for Sustainable Development Inc. [5] Wang, J., Dong, S., Yu, X. (2020). Advances of graphene- and graphene oxide-modified cementitious materials. Nanotechnology Reviews 9(1), pp. 465–477. DOI: https://doi.org/10.1515/ntrev-2020-0041. [6] Bhandari, M., Yue, J., Nam, I.W. (2025). Mechanical, electrical and fractural characteristics of carbon nanomaterial added cement composites. Applied Sciences 15(9), 4673. DOI: https://doi.org/10.3390/app15094673. [7] Hawreen, A., Bogas, J.A. (2018). Influence of carbon nanotubes on steel–concrete bond strength. Materials and Structures 51(4), pp. 1–16. DOI: https://doi.org/10.1617/s11527-018-1279-8. [8] O’Rear, E.A., Onthong, S., Pongprayoon, T. (2024). Mechanical strength and conductivity of cementitious composites with multiwalled carbon nanotubes: To functionalize or not? Nanomaterials 14(1), 80. DOI: https://doi.org/10.3390/nano14010080. [9] Konsta-Gdoutos, M.S., Metaxa, Z.S., Shah, S.P. (2010). Highly dispersed carbon nanotube reinforced cement-based materials. Cement and Concrete Research 40(7), pp. 1052–1059. DOI: https://doi.org/10.1016/j.cemconres.2010.02.015. [10] Chen, S., Wu, C., Yan, D. (2019). Binder-scale creep behavior of metakaolin-based geopolymer. Cement and Concrete Research 124, 105810. DOI: https://doi.org/10.1016/j.cemconres.2019.105810. [11] Gupta, S., Kua, H.W., Pang, S.D. (2020). Effect of biochar on mechanical and permeability properties of concrete exposed to elevated temperature. Construction and Building Materials 234, 117338. DOI: https://doi.org/10.1016/j.conbuildmat.2019.117338. [12] Hong, X., Lee, J.C., Ng, J.L. (2023). Effect of graphene oxide on the mechanical properties and durability of high strength lightweight concrete containing shale ceramsite. Materials 16(7), 2756. DOI: https://doi.org/10.3390/ma16072756. A A CKNOWLEDGEMENTS uthors greatly acknowledge the FRPS scheme (No. R&D/FRPS/2023-24/CV/06) and for the research assistance provided by BMS college of Engineering, Bangalore, Karnataka, India.

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