The effect of hybrid polyethylene and basalt fibres on the mechanical and durability properties of MWCNT-modified cement mortars

A multi-scale reinforced cement mortar was developed by combining 0.05% multi-walled carbon nanotubes (MWCNTs) with hybrid polyethylene fibre (PEF) and basalt fibre (BF). A total of 12 mixtures were prepared and evaluated for flexural and compressive strengths, rapid chloride migration, sulfate resistance (up to 120 days) and microstructure. Compared with the reference mixture without fibres or MWCNTs, mix P₂₀B₃₀ (0.20% PEF + 0.30% BF) showed an increase of 27% in 28-day flexural strength, an increase of 10% in 28-day compressive strength, a reduction in the non-steady-state chloride migration coefficient of 68% and a 72% decrease in sulfate-induced mass loss. These results identified P₂₀B₃₀ as the best-performing mixture on the basis of combined mechanical and durability indicators. The improvements are attributed to matrix/interfacial transition zone densification by MWCNTs and multi-scale crack bridging by hybrid fibres, which jointly restricted transport pathways and damage evolution.