Optimizing concrete performance: Influence of carbon nanotubes dispersion techniques

Given the challenges of decarbonizing materials commonly used in the construction industry and the promising use of nanoparticles in cement composites, this article aims to analyze the influence of carbon nanotubes (CNTs) dispersion techniques on concrete quality. To this end, multi-walled carbon nanotubes were pre-dispersed in Portland cement particles in isopropanol after mechanical stirring, sonication, and oven drying. Then, 0% (reference), 0.05%, and 0.10% CNTs were used to make thirty-six cylindrical specimens measuring 10 × 20 cm (diameter × height). The properties of compressive strength (f c ), tensile strength (f ct ), porosity (P), and ultrasonic pulse velocity (UPV) were measured. Scanning electron microscopy (SEM) was also carried out on the broken samples to capture any effect of the CNTs. The results were compared with those of similar studies in the literature, but which used other dispersion techniques and CNT contents. Compared to the reference samples, the concrete with CNTs showed significant improvements in f c (up to 23% increase), f ct (up to 35% increase), P (up to 12% reduction), and UPV (up to 4% increase). However, considering the low CNT contents used, the action of CNTs in the concrete was not detected using SEM images. The analysis and discussion of the results proved the effectiveness of pre-dispersion of CNTs in cement particles, but choosing CNTs in aqueous suspension with industrial dispersion tends to be a more practical and safer approach for improving the concrete quality and extend the useful life of structures built with this composite.