International Journal of Advanced Engineering Application

Mechanical Performance and Fire Resistance of Multi-Walled Carbon Nanotube-Reinforced Cementitious Composites: Tensile, Flexural, and Thermal Characterisation

Author(s):Aleksandra Nowak

Affiliation: Department of Civil and Structural Engineering, Warsaw University of Technology, Warsaw, Poland

Page No: 73-77

Volume issue & Publishing Year: Volume 3, Issue 6, 2026/06/10

Journal: International Journal of Advanced Engineering Application (IJAEA)

ISSN NO: 3048-6807

DOI:

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Abstract:
The incorporation of multi-walled carbon nanotubes (MWCNTs) into cementitious matrices represents a frontier strategy for engineering construction materials that maintain structural integrity under both mechanical loading and elevated-temperature exposure. Ordinary Portland Cement (OPC) composites suffer progressive strength degradation above 300 degrees C due to calcium silicate hydrate (C-S-H) dehydration, portlandite decomposition, and microcrack network development -- constraints that limit structural concrete performance in fire scenarios mandated under IS 456:2000 and Eurocode 2 fire exposure classes. MWCNTs, with tensile strengths of 11-63 GPa and elastic moduli of 270-950 GPa, offer a theoretically compelling reinforcement modality that bridges micro-crack propagation and enhances post-fire residual strength through their high aspect ratio bridging action across cementite fracture planes.
This study examines the mechanical and thermal properties of M30 grade cement composites incorporating MWCNTs at five dosage levels (0%, 0.1%, 0.2%, 0.3%, and 0.5% by weight of cement) subjected to ambient and post-fire (200 degrees C, 400 degrees C, 600 degrees C) test conditions. Properties evaluated include tensile strength (Brazilian split test), flexural strength and ductility index (three-point bending), thermal conductivity (transient hot-wire method), relative mass loss at 600 degrees C, and pore size distribution via SEM image analysis. Elemental characterisation by energy-dispersive X-ray spectroscopy (EDS) confirms MWCNT-matrix interaction sites at 28 days.
The 0.2% MWCNT composite achieves the highest ambient tensile strength (671 MPa; 15.7% above control), flexural strength (4.0 MPa), ductility index (2.7), and thermal conductivity (52.6 W/m.K), with minimum mass loss at 600 degrees C (2.6%). Post-fire tensile retention at 400 degrees C is 77.5% for the 0.2% mix versus 74.1% for the control, confirming superior fire resistance. SEM analysis reveals bridging filaments across cementite crack planes in MWCNT-modified specimens; EDS confirms elevated carbon intensity at crack interfaces consistent with nanotube concentration at fracture sites.

Keywords: multi-walled carbon nanotubes, MWCNT, cementitious composite, fire resistance, tensile strength, flexural strength, thermal conductivity, SEM, EDS, M30 concrete, post-fire performance

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