Self-sensing cementitious composites incorporated with botryoid hybrid nano-carbon materials for smart infrastructures

The botryoid hybrid nano-carbon materials were incorporated into cementitious materials to develop a new type of self-sensing cementitious composites, and then the mechanical, electrically conductive, and piezoresistive behaviors of the developed self-sensing cementitious composites with botryoid hybrid nano-carbon materials were comprehensively investigated. Moreover, the modification mechanisms of botryoid hybrid nano-carbon materials to cementitious materials were also explored. The experimental results show that the compressive strength and the elasticity modulus of the self-sensing cementitious composites botryoid hybrid nano-carbon materials decrease with the increase in the botryoid hybrid nano-carbon material content, while the Poisson's ratio does the opposite. The percolation threshold zone of the self-sensing cementitious composites botryoid hybrid nano-carbon materials is from 2.28 to 3.85 vol.%. The optimal content of botryoid hybrid nano-carbon materials is 3.38 vol.% for piezoresistivity of the self-sensing cementitious composites botryoid hybrid nano-carbon materials. The amplitude of fractional change in resistivity goes up to 70.4% and 28.9%, respectively, under the monotonic compressive loading to failure and under the repeated compressive loading within elastic regime. The piezoresistive stress/strain sensitivity reaches (3.04%/MPa)/354.28 within elastic regime. The effective modification of botryoid hybrid nano-carbon materials to electrically conductive and piezoresistive properties of cementitious materials at such low content is attributed to their botryoid structures, which are beneficial for the dispersion of botryoid hybrid nano-carbon materials and the formation of conductive network in cementitious materials. The use of botryoid hybrid nano-carbon materials provides a new bottom-up design and fabrication approach for nano-engineering multifunctional cementitious composites.