The Influence of Carbon Nanotubes on the Fracture Energy, Flexural and Tensile Behaviour of Cement Based Composites

Abstract

Due to the necessity to improve the mechanical properties of cement-based materials, carbon nanotubes (CNTs) have been studied to prepare cement composites. Once they present high tensile strength, if well dispersed and well adhered to the cement hydration products, they can improve the mechanical properties of a cement paste system. Because of that, an effective dispersion process is crucial. Studies involving CNTs dispersion in cement particles in presence of a non-aqueous media of isopropanol resulted in improvements in mechanical properties suggesting a good dispersion and strong bond between CNTs and cement particles. Considering that, the present paper analysed a cement paste reinforced with 0%, 0.05% and 0.10% of CNTs dispersed in a non-aqueous media of isopropanol through three-point bending tests in notched specimens and direct tensile tests. The influence of CNTs on the material fracture energy, flexural strength, and tensile strength was addressed. The results pointed out an improvement of 90% of fracture energy in composites with 0.05% of CNTs. The results of direct tensile tests indicate an improvement of about 20% tensile strength in cement paste with 0.05% of CNTs and images by scanning electron microscopy indicate a better dispersion by this proportion. These results suggest not only an effective dispersion of CNTs in cement matrix by the used dispersion methodology at a dosage of 0.05% of CNTs, but also that the cement composites properties may be improved by the presence of them.

Effect of multi-wall carbon nanotubes on the flexural performance of cement based composites

“…Furthermore, Mohsen et al [40] suggested that a CNTs' content 0f 0.25 wt% might be an ideal content for achieving better dispersion and optimal flexural strength. Similar results were reported when the MWCNT content is as low as 0.05-0.1% [38] or 0.03-0.25% [41].…”

“…To determine the effect of MWCNT content on the mechanical properties on cementitious composites, the compressive strength and flexural strength results are compared with literature data [33,34,36,[38][39][40][41][42][43][44][45] as plotted in Fig. 2.…”

“…To improve flexural strength, CNT can be used to increase the interfacial adhesion between the reinforcement and concrete leading to better flexural loading capacity (24% higher) of the composites [37]. Rocha et al [38] also reported that the flexural strength of cement composites can be increased by 46% with the addition of only 0.1% wt CNT.…”

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

“…Li et al [117] 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.…”