Multifunctional cementitious composites capable of self-sensing and self-healing of damages

The main purpose of the thesis is the development of multi-functional smart cement-based composites, in which self-healing and self-sensing properties are evaluated together with the addition of nano (carbon nano tube [CNT]) and micro-scale (carbon fiber [CF]) carbon-based materials to Engineered Cementitious Composites (ECC). In order to examine the self-healing and self-sensing properties of the developed composites under realistic environmental conditions and long-term sustainability, the short and long term effects of continuous water and wetting drying cure were examined within the scope of the thesis study. In addition, the effect of substitution of fly ashes with high and low ignition loss at different rates (fly ash / portland cement: 1,2; 2,2) in composites formed using carbon-based materials on the self-healing and self-sensing properties of the mixtures was evaluated. Control mixes without carbon based material were also prepared for comparison with mixtures containing carbon-based material. Self-healing tests were performed on undamaged (sound) and cracked (pre-loaded) samples by Rapid Chloride Permeability Test and electrical resistance tests. The mechanical properties of carbon-based composites were evaluated by compression and flexural tests, and compared with samples that were cracked by preloading and improved under specified curing conditions. Cracks belonging to the samples were followed by video microscope and the crack closing performances of each mixture were analyzed. In addition, SEM / EDX, TGA and XRD tests were performed in order to examine the microstructure of samples with self-healing / sensing capabilities, and each mixture was characterized separately. According to the results of the study, in general, the compressive and flexural strength of the samples containing carbon-based material sometimes decreased compared to the control samples, but the self-sensing performance (especially CNT) was found at a high level in electrical resistance tests. In addition, it was observed that the improvement in the cracks was pronounced in the preloaded samples, regardless of the mixing and curing conditions.