Mechano-Physical Properties and Microstructure of Carbon Nanotube Reinforced Cement Paste after Thermal Load

The aim of this research was to study the properties of cement reinforced with coconut fiber. The coconut fiber addition that uses in this research were 5, 10 and 15% by weight of cement. The cement paste and coconut fiber were mixed together and packed into an iron mold. Then, the specimens were kept at room temperature for 24 hours and were moist cured in the water bath at 3, 7 and 28 days. After that, the physical properties i.e. water absorption and density were examined. The microstructure was characterized by scanning electron microscopy (SEM). The results showed the surfaces of the coconut fibers were not smooth, spread with nodes and irregular stripes, which is covered with substances and other impurities. The compressive strength and flexural strength were also investigated. From the results, the mechanical properties were decreased with increasing coconut fiber content due to reducing density and higher porosity and water absorption compared to non-fiber cement paste and physical properties of fiber had been flexibility and smoother caused poor binding with cement. The best compressive strength and flexural strength results were obtained with the percentages of coconut fiber as 5% which value as 26.67 N/mm2 and 5.08 N/mm2 respectively.

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Preparation and piezoresistivity of carbon nanotube-coated sand reinforced cement mortar

Nanotechnology Reviews ◽

10.1515/ntrev-2020-0112 ◽

2020 ◽

Vol 9 (1) ◽

pp. 1445-1455

Author(s):

Song Gao ◽

Jianlin Luo ◽

Jigang Zhang ◽

Fei Teng ◽

Chao Liu ◽

...

Keyword(s):

Carbon Nanotube ◽

Cement Mortar ◽

Aqueous Suspension ◽

Ac Impedance ◽

Stress Sensitivity ◽

Multiwall Carbon Nanotube ◽

Impedance Technique ◽

Reinforced Cement ◽

Coated Sand ◽

Mechanical Strengths

Abstract Water and sand were used as the medium of multiwall carbon nanotube (MCNT) and prepared MCNT aqueous suspension and MCNT suspension-coated sand, respectively; afterwards, they were introduced into cement mortar (MNT/CM, MNTSM), respectively. Next, mechanical strengths and piezoresistive properties (DC resistivities (ρ v), AC impedances (Z r)) under cyclic loadings (σ c) of two types of MNT/CM and MNTSM nanocomposites were investigated to explore the intrinsic and self-sensing behaviors. Results reveal that MCNT can be evenly and well-coated on sand, which favors to achieve its intrinsic self-sensing property. Although the fraction changes in ρ v and Z r under the same σ c of MNTSM are both lower than those of MNT/CM, the stress sensitivity of MNTSM is only −1.16%/MPa (DC resistivity), −1.55%/MPa (AC impedance); its sensing linearity and stability (2.53, 2.45%; 2.73, 2.67%) are superior to those of MNT/CM (4.94, 2.57%; 3.78, 2.96%). Piezoresistivity using AC impedance technique is helpful to acquire balanced sensing sensitivity and stability while applied as intrinsic sensors in infrastructure.

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