Desenvolvimento e aplicação de compósitos cimentícios automonitorantes contendo nanotubos de carbono como fíler condutor

Abstract

Cementitious composites with carbon nanotubes (CNT) were investigated to understand how conductive and non-conductive constituents affect their self-sensing properties. Paste and mortar composites were evaluated, as well as the use of mortars for strain monitoring of concrete samples. During the development of the matrices, CNT content was varied, and insulating mineral admixtures and fine aggregates were used to modify the packing density and the continuity of the conductive paths of CNT. It was found that CNT had a predominant effect on the electrical and self-sensing properties, which also influenced how these properties are affected by the insulating constituents in the matrix. CNT contents of 0.5% and 0.75% resulted in the best performances. Incorporating mineral additions reduced CNT usage while preserving the electrical and self-sensing properties, and also densified the microstructure of the composites. Optimizing the sand content improved the mechanical and self-sensing performance of the mortars, with sandto-cement ratios between 1 and 2 yielding the best results. Samples embedded in concrete responded consistently to strains, proving to be an efficient and viable alternative to traditional structural monitoring sensors. The proper dosage of non-conductive components thus allowed for enhancing the self-sensing properties of the composites, contributing to future advancements and the implementation of improved matrices in the monitoring and safety of concrete structures.