Evaluation procedure for damage detection by a self-sensing cement composite

Health and safety are relevant in transportation infrastructures. Most health evaluations are performed by spot measurements using conventional transducers. This study aims to explore a self-sensing composite that can be integrated into a structural layer of a pavement or rail track to continuously evaluate the full layer performance in critical zones and anticipate damage occurrence. For this purpose, a 10 % cement-stabilized standard sand used in conventional structural layers was transformed into a self-sensing composite by synergistic incorporation of 3 % and 4 % multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs). In addition, Pluronic F-127 and tributyl phosphate 97 % (TBP) were used for better dispersion of carbon nanomaterials in the mixture, and these materials were compacted at maximum density and optimum moisture conditions. Through a detailed laboratory investigation, including piezoresistivity measurements, digital image correlation (DIC), and microstructure analysis through scanning electron microscopy (SEM), it was possible to propose a novel method to detect the propagation of damage under monotonic loading based on changing the slope of normalized electrical resistance against time. This was supported by a theoretical background able to explain that the emergence and propagation of damage result in increasing electrical resistance and hence fractional changes in resistance (FCR).