دانلود رایگان مقاله لاتین خواص مکانیکی مواد مرکب سیمان از سایت الزویر
عنوان فارسی مقاله:
خواص مکانیکی و تعدیل مواد مرکب سیمانی تقویت شده CNT
عنوان انگلیسی مقاله:
Mechanical and damping properties of CNT-reinforced cementitious composites
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Cementitious composites are the most commonly used building material in the world, but it is difficult for them to meet many aspects of the engineering demands due to their brittleness, low strength against tension, and cracking problem. Nowadays, the introduction of a variety of materials into the composites has been tried and with the development of nanotechnology, the introduction of nanomaterials such as nano-silica, carbon nanotubes (CNTs), and so on has become a hot spot for researchers [1,2]. CNTs, a tube-shaped allotrope of carbon like rolled graphene, are potentially very advantageous for nano-strengthening of the cement matrix because of their ultra-high aspect ratio (length-todiameter ratio), ultra-large surface area, and outstanding mechanical properties [3–6]. CNTs are categorized as single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). CNTs can have diameters ranging from 1 to 100 nm and lengths in the range of 0.1–100 lm [7]. Typical properties of CNTs include a tensile strength 100 times greater than that of steel, an ultimate strain of more than 10%, and a Young’s modulus approaching 1 TPa [8,9]. Unlike microfiber reinforcements in cement matrix that help to delay the development of microcracks, CNTs which are distributed at a much finer scale than common fibers, stop crack growth at the nanoscale and hinder the creation of micro-cracks [10]. The main difficulties in the application of CNTs in cement matrix relate to the dispersion of the CNTs and the efficient bonding of the CNTs with cement hydration products [11]. There is a strong tendency for individual CNTs to agglomerate due to Van der Waals attraction, which originates from their polarizable extended p-electron systems [10,12,13]. Commonly, the mixing process using a Hobart mixer cannot ensure proper dispersion of CNTs within the matrix [6], so CNTs are dispersed in aqueous solutions before mixing [14]. The most common ways to make CNT solutions are through the use of ultrasonication and surfactant. Ultrasonication is a physical method of dispersing CNTs by exposing them to cavitation, which exfoliates them [15]. However, Van der Waals forces exist permanently, so the solutions are temporarily dispersed by sonication [16]. Surfactant, which contains hydrophobic groups and hydrophilic groups, is a chemical method to attach hydrophobic groups on the CNT surface while hydrophilic groups generate electrostatic repulsion that separates the individual CNTs from bundles and change the wettability of the CNT surface [16–18]. Combined with ultrasonication, surfactant can keep CNT solutions stable. In addition, the functional groups, such as carboxyl (–COOH) and hydroxyl (–OH) groups, which are attached to the CNT structure with H2SO4 and HNO3 mixture, can also ameliorate the CNT dispersion in aqueous solutions [19]. So far, the dispersion of CNTs has been widely researched and solved well by many surfactants combined with sonication, such as superplasticizer (SP) and sodium dodecylbenzene (SDBS) [3,20]. However, there is very limited knowledge about the actual strength of the bonding occurring between the CNTs and the hydrates [21]. The bonding between CNTs and cement hydrates is often weak due to the very low surface friction between them [22]. Szleifer and Yerushalmi-Rozen [16] researched the interactions of polymers and CNTs, and their work indicated that different forms of modifi- cations existed on the CNT surface structure due to the decoration of polymers on it. Trettin and Kowald [23] employed different types of polycarboxylate-based SPs as surfactants and found that the CNTs produced different levels of improvement in the compressive and bending strengths, showing the interfacial bonding between the tubes and matrix is affected by the types of SPs. In addition, the incorporation of CNT in cement paste created multiform interfaces between CNTs and the matrix, which may change the damping properties of cement paste, especially considering the ultra-large surface area [24–26]. Therefore, it can create excellent value for the application of CNTs in aseismic engineering. Cinquin et al. [27] reported the effect of interface bonding of glass- fiber-reinforced composites with dynamic mechanical analysis (DMA), which gives an accurate measurement of interfacial damping. So it is feasible to investigate the damping performance of CNT-reinforced composites and the interface reaction between the CNT surface and the adjacent cement hydrates through the use of the DMA technique. The present work first focused on the dispersion ability of the surfactants and the morphology of CNTs in cement hydrates and then compared the results obtained with the compressive and flexural measurements performed on a referenced plain cement and CNT/cement composites containing different amounts of CNTs. Furthermore, another aim of this study is to research the damping performance of CNT/cement composites with varying CNT contents using DMA. The effects of different surfactants on the modi- fication of the CNT surface and the bonding strength between the CNTs and cement hydrates are discussed. The combining mechanism (physical or chemical interaction) between the CNTs and cement paste was investigated and analyzed.
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کلمات کلیدی:
The Characteristics of CNT/Cement Composites with Acid-Treated ... https://www.hindawi.com/journals/amse/2015/308725/ by ST Kang - 2015 - Cited by 5 - Related articles Jul 2, 2015 - These two methods have been employed in past research on cement composites reinforced with CNTs. The third method, which involves ... Progress in Research on Carbon Nanotubes Reinforced Cementitious ... https://www.hindawi.com/journals/amse/2015/307435/ by Q Li - 2015 - Cited by 6 - Related articles Jul 13, 2015 - Progress in the field of CNTs presents a potential opportunity to ..... Mechanical properties of MWCNTs-reinforced cement composites are ... [PDF]Mechanical Properties and Durability of CNT Cement Composites www.mdpi.com/1996-1944/7/3/1640/pdf by M del Carmen Camacho - 2014 - Cited by 17 - Related articles Feb 28, 2014 - or even the deterioration of the cement-composite properties while using ... corrosion of steel reinforced CNT cement pastes with different CNT ... Effect of Different Parameters on Properties of Multiwalled Carbon ... link.springer.com/article/10.1007/s13369-016-2181-8 by T Manzur - 2016 - Cited by 2 - Related articles May 12, 2016 - The exceptional mechanical properties of carbon nanotube (CNT) such as ... on properties of CNT-reinforced cementitious composites through ... [PDF]Mechanical and damping properties of CNT-reinforced cementitious ... iranarze.ir/wp-content/uploads/2016/11/E485.pdf Oct 17, 2016 - Mechanical and damping properties of CNT-reinforced cementitious composites. K.M. Liew a,b,*. , M.F. Kai a,b, L.W. Zhang c,* a Department of ... Electrical Properties of Carbon Nanotubes Cement Composites for ... https://www.researchgate.net/.../252390320_Electrical_Properties_of_Carbon_Nanotube... Cement pastes reinforced with Multi-Walled carbon Nano Tubes (MWNTs) are smart materials with piezoresistivity properties. Adding carbon nanotubes to the ... Potential of carbon nanotube reinforced cement composites as ... https://uta.influuent.utsystem.edu/.../potential-of-carbon-nanotube-reinforced-cement-... Considering the mechanical properties of carbon nanotubes (CNTs) and the test results of CNT reinforced cement composites, it is apparent that such ... Searches related to properties of CNT-reinforced cementitious composites carbon nanotubes reinforced concrete carbon nanotubes in concrete ppt carbon nanotubes applications in concrete carbon nanotubes in concrete pdf eden concrete sci hub google scholar
