A comprehensive morphology study on the carbon nanotube agglomerations in cementitious composite

To comprehensively understand the fundamental role of carbon nanotubes (CNTs) in cementitious composites, three independent methods were employed to investigate the morphological characteristics of the composites. The embedding method and the depositing method controlled the direction of hydrate reactions by compulsorily segregating CNTs and cement grains, helping to more accurately deduce the formation process of various morphologies. The sectioning method used focused ion beam for precise cutting, enabling in-situ morphology information that cannot be observed through mechanical polishing. This study provides the first visual evidence to demonstrate that the micro-agglomerations of CNTs were sufficiently incorporated into the hydration products, indicating that CNT agglomerations may not be the primary cause for the decline in the mechanical properties of carbon nanotube cementitious composites. Furthermore, this study proposes the physical entrapment mechanism as a substitute for the ambiguous nucleation mechanism.