Investigation of the electrical sensing properties of cementitious composites produced with multi-wall carbon nanotubes dispersed in NaOH

The use of nanomaterials, such as carbon nanotubes, in cement-based composites has been a topic of considerable attention in recent years due to their potential to monitor civil structures and infrastructures. One of the main challenges is the adequate and efficient dispersion of the carbon nanotubes due to their nanoparticle size and the high adhesion forces developing among them. The most common strategy to tackle this challenge is to use sonic treatments that are unfeasible for field-scale implementations. Alternatively, specific chemicals (i.e. surfactants) facilitating nanotube mixing are used, but this often results in poor mechanical properties, reduced electrical conductivity and high environmental impact of the composites. This works has as the main aim to analyze the self-sensing properties of the cementitious composites developed with NaOH as the dispersing agent. For this purpose, the work investigates electrical and sensing properties of cement-based nanocomposites with different contents of multi-wall carbon nanotubes (MWCNT), namely 1%, 1.5%, and 2% with respect to cement weight, previously dispersed in NaOH aqueous solution. The composites' fresh and electrical properties are evaluated, and a microstructural analysis is carried out. The major findings of the work reveal that cement paste samples with different contents of MWCNT presented increasing sensing properties up to 2%, and that the dispersing strategy was promising despite its simplicity.