Multifunctional materials and nanocomposite sensors for civil infrastructure monitoring

Multifunctional materials—or material systems intentionally encoded with a multitude of engineering functionalities—are revolutionizing civil engineering practice by offering new materials that can simultaneously resist loads and self-sense for damage. These new developments have been made possible through technological breakthroughs in the nanotechnology domain. New nanomaterials with impressive properties and scalable manufacturing methods have enabled the design of these multifunctional materials and nanocomposites. The “bottom-up” design of large-scale structural materials starting at molecular length scales is now possible (and even cost-effective). The objective of this chapter is to showcase three types of nanomaterial-based multifunctional materials that have and will continue to impact the civil engineering community. Particular attention will be paid to materials assembled using three unique nanomaterials, namely, carbon black, carbon nanotubes, and graphene. The reason for focusing on these three carbon-based nanomaterials is because significant amounts of research have been conducted over the past few decades, and the technology has matured to the verge of commercial adoption and large-scale implementations. This chapter will begin with an introduction, followed by a discussion of the characteristic properties of these carbon-based nanomaterials. Section 16.3 will showcase piezoresistive thin-film coatings and epoxy-based nanocomposites for strain sensing and damage detection, as well as smart and self-sensing cementitious composites. Section 16.4 will illustrate the applications of electrical impedance tomography conductivity mapping for spatial damage and strain mapping. Section 16.5 will elucidate photoactive nanocomposite sensors for strain and damage detection. The development of mechanoluminescence–optoelectronic composites for strain sensing will be discussed in Section 16.6. This chapter concludes with a brief summary in Section 16.7.