Sensing capability of nanomodified Portland cement composites

Abstract: Sensing cement-based composites refer to composites that have sensing functionality that can measure several physical and chemical parameters. Sensing cement-based composites are fabricated by incorporating some functional fillers, such as conductive fibers (CFs), carbon nanofibers (CNFs), carbon nanotubes (CNTs), and graphene, into conventional concrete. The self-sensing phenomenon in a material is based on the property of an electrically conductive material to show a change in its electrical resistivity. Several factors affect the electrical resistivity of cement-based composites. These include, for example, the type of added conductive phases, their concentration, the microstructure of the surrounding binder matrix, and its composition or moisture content. Variable stress, strains, relative humidity, temperature, or crack development can all affect conductivity.A novel material, so-called "nanomodified Portland cement," is an in situ synthesis of carbon-based materials on untreated Portland cement particles. The synthesized method is based on the application of a chemical vapor deposition process (CVD). The nanomodified Portland cement was produced and used as a conductive filler in a sensing cement-based composite to improve the dispersion issue of the carbon-based materials, which have a hydrophobic nature and the tendency to agglomerate in the cement-based composites.The sensing capability of the nanomodified Portland cement composites was studied and compared with other conductive materials, revealing the percolation threshold and tunneling phenomena as possible explanations for the sensing mechanism with and without mechanical deformation.The achieved results of this study suggest that nanomodified Portland cement is a promising material for use in sensing cement-based composites as it exhibits high sensitivity to compressive stress and strain, humidity, and temperature. Furthermore, it has the potential to be utilized in the development of integrated monitoring systems for concrete structures.

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