Nano-Scale Tailoring of Engineered Cementitious Composites for Simultaneous Achievement of Enhanced Healing and Sensing Functionalities

Abstract

Autogenous self-healing can be a handy tool for concrete material to self-repair its own damage. On the other hand, to keep infrastructures in a serviceable state, it is also important to identify and assess any structural damage (cracks) as early as possible, before losing complete and/or sectional integrity. In this regard, efforts can be made to make concrete material work like a sensory material by making its nature electrically conductive (i.e. selfsensing) and responsive to any changes in applied strains. Engineered Cementitious Composites (ECCs) are new-generation ductile concretes capable of favouring autogenous self-healing through the formation of micron-size cracks upon straining. ECCs are also characterized by piezoresistive (self-sensing) response meaning that they exhibit strong dependence of electrical resistivity to the applied loading. Within this context, an attempt has been made here to further nourish both autogenous self-healing and self-sensing capabilities of ECCs by tailoring the matrix properties with different nanomaterials. With the purpose of improving self-healing and self-sensing attributes of ECC material, nano-silica and carbon nanotubes were simultaneously incorporated in mixture compositions, respectively. Tests were performed on sound and pre-loaded (almost-failed) prismatic ECC specimens under four-point bending loading. Both self-sensing and self-healing properties were evaluated before/after the introduction of microcracking and upon exposure to further curing. Results revealed that proposed nano-modification of ECC mixtures significantly improved the autogenous self-healing and self-sensing capabilities simultaneously. Outcomes of this study are believed to make a marked impact on true infrastructural sustainability by not only reducing the frequency of repair/maintenance applications but also making infrastructures much smarter to easily track their own damage.