Carbon nanofiber embedded cement composites: Properties and promises as sensor – A review

Abstract

Modification of conventional concrete materials with nanomaterials was commenced over decades to enhance their properties. However, a novel approach is the modification of the electromechanical characteristics of the cement composite to transform the composite into a cement-based sensor. These cement-based sensors have widespread implementations in the performance measurement of structural components such as traffic pavements, beams, columns, etc. The most desirable material to increase the composite conductivity of cement is considered to be carbon nanofiber. The self-sensing potential of carbon nanofiber composite when a crack or deformation occurs has been discussed in this paper. The purpose of this review is to explore the properties of an embedded carbon nanofiber cement composite that transforms composite into a cement-based sensor. With the support of SEM investigations, the analysis also presents the various causes behind electromechanical characteristics. From the comprehensive examination, it is established that, due to its high conductivity, carbon nanofiber provides the concrete with self-monitoring behavior. A hybrid combination of carbon nanofiber with other nanomaterials will improve self-sensing more than carbon nanofiber alone. The carbon nanofiber not only detects the growth of micro-cracks, but it also helps to retain the concrete compactness. Carbon nanofibers also resist the micro-cracks and yield higher strength, higher youngs modulus, better resistance to fatigue and ductility. Besides, excess nanoparticles result in increased porosity. Thus, optimum carbon nanofiber content is essential for cement-based sensors used in Structural Health Monitoring.