Mechanical properties and microstructure of multi-walled carbon nanotube-reinforced cementitious composites under the early-age freezing conditions

Effect of Environmental Exposure on the Pore Structure and Transport Properties of Carbon Nanotube-Modified Mortars

“…This has been attributed to the filling of mesopores and the creation of a denser microstructure due to a good interaction between the hydration products and CNTs. This finding is also supported by the work of Guan et al [ 21 ], which demonstrated a formation of a compact microstructure after the addition of CNTs. A reduction in porosity ranging between 25% and 47%, also linked with the growth of hydration products into the voids and inter-hydrate spaces of cementitious matrix, has been demonstrated in [ 22 ] for CNTs and CNTs-graphene oxide cementitious nanocomposites.…”

“…The imperative need to improve the performance of conventional cementitious materials and to impart multi-functionality and smartness in structures has stimulated great scientific interest towards the use of carbon-based nano-inclusions in cementitious materials [ 13 , 14 , 15 , 16 , 17 ]. Many studies, based on microstructural analysis, suggest that carbon nanotubes (CNTs) contribute to the refinement of the pore network as well as bridging of micro-cracks [ 18 , 19 , 20 , 21 , 22 , 23 ]. More specifically, in the work of Parveen et al [ 18 ], Nochaiya and Chaipanich [ 19 ], and Ghahari et al [ 20 ] authors reported a drop in both porosity and total surface area in CNT-modified cement-based materials.…”

“…A reduction in porosity ranging between 25% and 47%, also linked with the growth of hydration products into the voids and inter-hydrate spaces of cementitious matrix, has been demonstrated in [ 22 ] for CNTs and CNTs-graphene oxide cementitious nanocomposites. Furthermore, in [ 21 , 23 ] the study of the fracture surface of CNT-modified cementitious materials revealed a crack-bridging effect of the nano-phase. This effect leads to crack reduction and enhancement of strength and fracture energy.…”

The Effect of Carbon Nanotubes on the Flowability, Mechanical, Microstructural and Durability Properties of Cementitious Composite: An Overview

“…Ultrasonication can be used to achieve a homogeneous dispersion of CNTs in the cementitious matrix, combining sonication with shear mixing methods, such as the mechanical, magnetic, and hand-stirring methods. The ultrasonication process is the most used technique [3,9,29] due to its rapid separation of nanoparticles from aggregated bundles and collapsing cavitation bubbles. Well-designed ultrasonication with sufficient ultrasonication energy can disperse the CNTs uniformly.…”

“…Moreover, the compatibility between cement hydration and CNTs was observed to be very good, and the microstructure of the hydration product improved. Carbon nanotubes can act as a nucleating agent [19,29] for calcium silicate hydrate (C-S-H) and enhance the mechanical properties of cementitious composites (Figure 9). CNTs introduced into cement-based composites create sites for the hydration process and lead to a stronger and denser microstructure.…”