Hybrid effect of carbon nanotubes and polypropylene fibers on mechanical properties and fire resistance of cement mortar

Abstract

The hybrid effect of multi-walled carbon nanotubes (MWCNTs) and polypropylene (PP) fibers on the mechanical properties and fire resistance of Portland-cement-based mortar was experimentally investigated in this study. MWCNTs of 0.1%, 0.25%, and 0.5% by weight were added, and PP fibers were added at a constant dosage of 0.2% by volume. The strength of the mortar exposed to various temperatures up to 1,000 °C was determined. It was found that the addition of 0.1% MWCNTs improved the compressive strength and permeability of the mortar. Furthermore, the study showed that cement mortar with a high fire resistance could be developed by adding 0.25% MWCNTs and 0.2% PP fibers in the composite. After being heated to 1,000 °C, the mortar produced with this optimal mix exhibited a residual compressive strength of approximately 40%, which was 19% higher than that observed using plain mortar. Microstructure observations indicated that bridging effect of MWCNTs and melting of PP fibers work together for improving the fire resistance of mortars.