Multifunctional cementitious composites for damage- resistant highway structures

The development of self-sensing (piezoresistivity) feature which is one of the non-structural properties of cementitious composites to be multifunctional is under focus in the present thesis. This capability is considered as one of the best alternatives to continuously monitor the damage and deformations of highway structures. The experimental program in this study was divided into four parts. The first part dealt with the performing of a number of mixing methods to well disperse the different carbon-based electrically conductive materials (ECM) within the cement-based matrices. Four types of ECM, namely carbon fiber, carbon nanotubes, graphene nanoplatelets and carbon black, were employed to activate this property. The optimization phase of ECM concentration within the cementitious composites using the best mixing method, was carried out within the second part. To examine the self-sensing capability of the developed carbon-based cementitious composites under several loading scenarios, different electrical testing configurations were investigated within the third part of the experimental program. The fourth part of the study highlighted on the self-sensing performance of the developed multifunctional cementitious composites (MCC) under cyclic flexural and monotonic uniaxial compression loadings. Moreover, the self-sensing behavior was compared with the dielectric cement-based materials. The effect of curing age on the self-sensing behavior was, also, investigated. The results showed that the incorporation of carbon-based ECM within the cementitious composites have a significant effect on monitoring the damage and deformation of cement-based materials effectively.