دانلود رایگان مقاله لاتین اثر نانوبلور سلولز در خمیر سیمان از سایت الزویر
عنوان فارسی مقاله:
تاثیر نانوبلورهای سلولز در ساختار خمیر سیمان
عنوان انگلیسی مقاله:
The influence of cellulose nanocrystals on the microstructure of cement paste
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Cellulose nanocrystal (CNC) is the crystalline part of the cellulose materials, which can be extracted from trees and a variety of plants [1]. As a reinforcement material, CNC has a few extraordinary advantages, including biodegradability, high abundance, low cost, and excellent mechanical properties [1]. Recently, CNCs have been found to improve the flexural strength of cement composites due to an increase in the degree of hydration (DOH) [2] which is possibly aided by a mechanism referred to as short circuit diffusion (SCD). The basic prerequisite for SCD is the adsorption of CNCs on the surface of cement particles, acting as the pathway to preferentially transport water from pores to unhydrated cement cores. Such capability can be attributed to the high hydrophilicity and hygroscopicity of the CNCs [3]. A competing mechanism has also been identified for CNC concentrations larger than 0.2 vol % where agglomerates induce stress concentrators limiting the strength of the cement pastes [2]. This issue was subsequently addressed by Cao et al. [4] with ultrasonication (or sonication) to disperse the CNCs in the aqueous suspension before mixing with cement. The concentration of the CNCs adsorbed on the cement particles is an important factor as it directly influences the SCD. For simplicity the CNCs in the fresh cement paste are categorized as two types: the “free” CNCs in the water and the “adsorbed” CNCs on cement surface (abbreviated as fCNCs and aCNCs, respectively) as illustrated in Fig. 1. While both types of CNCs are in solution, the main difference is that the aCNCs are hard to move, as they adhere to the cement particles and the fCNCs can freely move in the aqueous suspension. The classification and quantification of these two types of CNCs are important for four reasons: we hypothesize that (1) the SCD is primarily governed by the amount of aCNCs; and (2) the strength of the cement is largely limited by the CNC agglomeration; we also lack sufficient information about (3) therole the fCNCs on the cement properties; (4) the mobility of CNCs in the cement paste. We present a novel experimental approach to measure the concentrations aCNCs and fCNCs and their effect on SCD.
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کلمات کلیدی:
The influence of cellulose nanocrystal additions on ... - ResearchGate https://www.researchgate.net/.../270509995_The_influence_of_cellulose_nanocrystal_a... Cellulose nanocrystal CNC Degree of hydration Ball-on-three-ball flexural test Steric ... The DOH and flexural strength were measured for cement paste with WRA and CNC to evaluate .... modify the microstructure and improve the mechanical. [PDF]An Investigation into the Properties and Microstructure of Cement ... www.mdpi.com/1996-1944/10/5/498/pdf by J Flores - 2017 May 4, 2017 - Keywords: CNC; cement mixture; hydration; microstructure. 1. Introduction ...... nanocrystals on the microstructure of cement paste. Cem. Concr. Portland Cement Paste Modified by TiO2 Nanoparticles: A ... pubs.acs.org/doi/abs/10.1021/ie4011595 by D Feng - 2013 - Cited by 21 - Related articles Jul 22, 2013 - Atomic force microscopy was introduced to observe the microstructure of nanomodified Portland cement paste, and the results show that the ... Portland Cement Paste Modified by TiO2 Nanoparticles - American ... pubs.acs.org/doi/pdf/10.1021/ie4011595 by D Feng - 2013 - Cited by 22 - Related articles Jul 22, 2013 - nanoparticles at 0.1, 0.5, 1.0, and 1.5% by mass of cement. The flexural strengths of .... microstructure of the hardened Portland cement paste. View - Forest Products Laboratory - US Forest Service https://www.fpl.fs.fed.us/documnts/pdf2015/fpl_2015_cao001.pdf by Y Cao - 2015 - Cited by 24 - Related articles Nov 18, 2014 - cement paste with WRA and CNC to evaluate this hypothesis. Our results .... the mechanical properties and (3) the microstructure. While iso-. Patent US20160075601 - Cellulose nanocrystal additives and ... www.google.com/patents/US20160075601 Mar 17, 2016 - The invention provides a cement paste composition comprising cement, cellulose nanocrystals, and optionally water. The cellulose nanocrystals can be ... Structure of Cellulose Particles. [0063]. A wide range of cellulose ... Yizheng Cao - Google Scholar Citations https://scholar.google.com/citations?user=I1DpDHEAAAAJ&hl=en Albany Molecular Research Inc. (AMRI) - amriglobal.com Jet mill grinding of portland cement, limestone, and fly ash: Impact on particle ... The influence of cellulose nanocrystals on the microstructure of cement paste. Natural Cellulose Nanofibers As Sustainable Enhancers in ... journals.plos.org/plosone/article?id=10.1371/journal.pone.0168422 by L Jiao - 2016 - Related articles Dec 22, 2016 - However, cellulose nanocrystals are typically prepared by acid .... Fig 5 shows the microstructures of the reference and cement paste with ...
