Influence of Carbon Nanotubes on the Mechanical Behavior and Porosity of Cement Pastes Prepared by A Dispersion on Cement Particles in Isopropanol Suspension

Abstract

Cement composites prepared with nanoparticles have been widely studied in order to achieve superior performance structures. The incorporation of carbon nanotubes (CNTs) is an excellent alternative due to their mechanical, electrical, and thermal properties. However, effective dispersion is essential to ensure strength gains. In the present work, cement pastes were prepared incorporating CNTs in proportions up to 0.10% by weight of cement, dispersed on the surface of anhydrous cement particles in isopropanol suspension and using ultrasonic agitation. Digital image correlation was employed to obtain basic mechanical parameters of three-point bending tests. The results indicated a 34% gain in compressive strength and 12% in flexural tensile strength gains, respectively, as well as a 70% gain in fracture energy and 14% in fracture toughness in the presence of 0.05% CNTs were recorded. These results suggest that CNTs act as crack propagation controllers. Moreover, CNT presence contributes to pore volume reduction, increases the density of cement pastes, and suggests that CNTs additionally act as nucleation sites of the cement hydration products. Scanning electron microscopy images indicate effective dispersion as a result of the methodology adopted, plus strong bonding between CNTs and the cement hydration product. Therefore, CNTs can be used to obtain more resistant and durable cement-based composites.

Nanostructure and Fracture Behavior of Carbon Nanofiber-Reinforced Cement Using Nanoscale Depth-Sensing Methods

“…In this study, carbon nanofibers are dispersed using a multi-step process that involves high-energy pre-dispersion using ultrasonic energy followed by low-energy dispersion using un-hydrated cement particles via high shear mixing and mechanical stirring. Recent work by Rocha and coworkers [ 43 , 44 ] has shown mentioned, please confirm that unhydrated cement particles provide an efficient means to disperse carbon nanofibers in cement matrices. In addition, a high-shear mixing step is incorporated to accelerate calcium silicate hydrate formation [ 45 ].…”

Graphene oxide-incorporated cementitious composites: a thorough investigation

“…CNTs possess strong van der Waals forces, which tend to form CNT bundles [48]. In studies conducted on CNT-reinforced cement composites, it was concluded that incorporating CNTs can accelerate the hydration process and improve mechanical strength [49][50][51]. The main mechanism in CNT-incorporated cement composites was found to be the nucleation effect, which helped fill up the gaps pertaining to micro-sized capillary pores.…”

“…48 In studies conducted on CNT-reinforced cement composites, it was concluded that incorporating CNTs can accelerate the hydration process and improve mechanical strength. [49][50][51] The main mechanism in CNT-incorporated cement composites was found to be the nucleation effect, which helped fill up the gaps pertaining to micro-sized capillary pores. Furthermore, The crack-bridging, pull-out and filling mechanisms of CNTs were found to be beneficial for producing a more compacted and denser microstructure by filling the existing voids between CSH products and improving the mechanical properties of cementitious composites.…”

Cement Composites with Carbon‐Based Nanomaterials for 3D Concrete Printing Applications – A Review

“…demonstrated that MWCNTs at 0.1 % enhanced the flexural strength by 22 % and at 0.05 % the toughness by 54 %, while the highest enhancement in the compressive strength was 17 % at 0.2 % optimum MWCNTs content. Rocha and Ludvig [118] reported that the incorporation of 0.05 % CNTs enhanced the compressive strength, flexural strength, and toughness by 34 %, 12 %, and 14 %, respectively.…”