The effect of shape memory alloy, steel, and carbon fibres on fresh, mechanical, and electrical properties of self-compacting cementitious composites

Abstract

This paper presents the initial results of a two-phase research project for developing re-centring self-sensing cementitious composites. The focus here is on fresh, mechanical, and electrical properties of the developed cementitious composites. Nickel-titanium (NiTi) superelastic shape memory alloy (SMA) fibres and carbon fibres were used in this study. The performance of composites was studied based on the slump test, four-point bending test, flexural toughness, compression test, direct tensile test, and electrical conductivity test. The performance of SMA fibre-reinforced self-compacting cementitious composites was also compared with their steel fibre-reinforced counterparts. The addition of SMA and steel fibres slightly decreased the relative slump while carbon fibres reduced the flowability of mixture significantly. The increase in SMA and steel fibre content enhanced the flexural and tensile post-peak performance of composite, especially for specimens containing 1%–1.5% fibres by volume. Compressive strength was observed to decrease slightly by using SMA and steel fibres up to 1%, after which a reverse trend was detected. Adding SMA and steel fibres up to 1.5% did not affect the conductivity of composite considerably. On the contrast, carbon fibres even at low content (i.e., 0.1%) increased the conductivity of the composite substantially. The percolation transition zone detected for carbon fibre-reinforced cementitious composites showed an optimum carbon fibre dosage of 0.3% in terms of electrical conductivity.