Experimental investigation on effect of multi-walled carbon nanotubes concentration on flexural properties and microstructure of cement mortar composite

• Main Authors: Yousefi, Ali, Bunnori, Norazura Muhamad, Khavarian, Mehrnoush, Hassanshahi, Omid, Majid, Taksiah A.
• Format: Conference Proceeding
• Language: English
• Subjects: Agglomerates; Beams (radiation); Bend tests; Cement; Cement reinforcements; Composite materials; Dispersion; Flexural strength; Microstructure; Modulus of elasticity; Modulus of rupture in bending; Mortars (material); Multi wall carbon nanotubes; Nanotubes; Properties (attributes); Strain; Toughness; Weight
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/1.5005663

Multi-walled carbon nanotubes (MWCNTs) with extraordinary properties have shown a promising role toward enhancing the flexural performance of cement composites. This paper investigates the effect of concentrations of MWCNTs on major flexural properties of cement mortar composites, including flexural strength, strain capacity, modulus of toughness, and modulus of elasticity. For this purpose, cement mortar reinforced with various concentrations of MWCNTs (0.02, 0.05, and 0.1 wt.% by weight of cement). Dispersion of MWCNTs was carried out using ultrasonic energy and concrete superplasticizer as surfactant agent. Prismatic beams of sizes 100 mm×100 mm×500 mm were fabricated and four-point bending tests were performed on the beam specimens at the age of 28 days. The results from bending tests indicated substantial improvements in the flexural strength, strain capacity and modulus of toughness of MWCNT-cement mortar, while the modules of elasticity remained constant. It was observed that specimens reinforced with 0.05 wt.% of MWCNTs exhibited higher flexural properties enhancement. Besides, it was noticed that with the increase of MWCNTs content, the flexural properties of MWCNT-cement mortar increased. The microstructure observation of MWCNT-cement mortar demonstrated well dispersion of nanotubes with concentration of 0.05 wt.% but large agglomerates and bundles of MWCNTs depicted within the sample with higher loading of MWCNTs (0.1 wt.%). It was concluded that the properties enhancement of MWCNT-cement composites highly depends on the concentration of MWCNTs and the level of dispersion of nanotubes in the cement matrix.