CNT-cement based composites: fabrication, self-sensing properties and prospective applications to Structural Health Monitoring

Degradation phenomena can affect civil structures over their lifespan. The recent advances in nanotechnology and sensing allow to monitor the behaviour of a structure, assess its performance and identify damage at an early stage. Thus, maintenance actions can be carried out in a timely manner, improving structural reliability and safety. Structural Health Monitoring (SHM) is traditionally performed at a global level, with a limited number of sensors distributed over a relatively large area of a structure. Thus, only major damage conditions are detectable. Dense sensor networks and innovative structural neural systems, reproducing the structure and the function of the human nervous system, may overcome this drawback of current SHM systems. Miniaturization and embedment are key requirements for successful implementation of structural neural systems. Carbon nanotubes (CNTs) can play an attractive role in the development of embedded sensors and smart structural materials, since they can provide to traditional cement based materials both structural capability and measurable response to applied stresses, strains, cracks and other flaws. In this paper investigations about CNT/cement composites and their self-sensing capabilities are summarized and critically revised. The analysis of available experimental results and theoretical developments provides useful design criteria for the fabrication of CNT/cement composites optimized for SHM applications in civil engineering. Specific attention is paid to the opportunities provided by new RF plasma technologies for the functionalization of CNTs in view of sensor development and SHM applications.