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1、土木工程中的纳米技术-毕业设计外文翻译 毕业设计外文文献翻译院 系:土木工程与建筑系年级专业:2009级土木工程专业姓 名:余丽珠学 号:0909022214附 件: Nanotechnology in Civil Engineering 指导老师评语: 指导教师签名: 年 月 日 中文译文: 土木工程中的纳米技术【摘要】为了拓宽视野,本文对土木工程中的纳米技术的实践意义和创新作了阐述。它创造了具有新特性和功能的材料设备系统。纳米技术在构建创新基础设施系统中的作用对土木工程的实践和拓宽领域带来了革命性的改变。本文首先介绍了纳米技术和它们跨学科应用的优缺点,其次是土木工程一般的背景资料和目前的发
2、展情况。此外,阐述了无论在市场上还是准备用于建筑行业的功能导向的纳米技术材料和产品的细节以及一定时间内可能导致的后果。列举了一些目前纳米技术在世界各地不同部分的土木工程领域的应用实例。对在最具挑战性的经济因素下它的实用性进行了简要的讨论。最后是未来的发展趋势,纳米技术的发展对土木工程向着更经济的基础设施,具有较长使用寿命和低成本的潜在影响的探讨。【关键词】土木工程,纳米材料,纳米技术,可持续发展。一、简介A.背景 作为建筑行业的人肯定都对获得原材料,把它们组合在一起然后把它们构建成一个可识别的形式的概念非常熟悉。建筑成品是一个被动的物体。随着环境影响和项目业主的滥用它的功能在慢慢衰退。建筑绝不
3、是一门新的科学或技术,但在其历史上已经发生了很大的变化。同样,纳米技术也不是一门新的科学和技术,而更可以说是一个扩展的科学和技术。粒子的大小是关键因素,在纳米技术中(任何事物,从一百或者更多下降到几纳米,或10-9m)大大的改变了材料的特性。另一个重要方面是,作为纳米尺寸的粒子,在表面上原子的比例相对于内部增加会产生新的属性。正是这些“纳米效应”,最终确定了我们所熟悉的“宏观” 的所有属性,这正是纳米技术的力量来源?如果我们可以在纳米尺寸上操纵元素,那就可以影响其宏观性质,并产生新材料和新工艺。B.什么是纳米? 纳米,希腊文中”侏儒”的意思。一纳米是一米的十亿分之一。”纳米技术”的定义有很多,
4、但一般是指在0.1100nm尺度的空间内来研究理解物质。控制在纳米尺寸上的意义与重要性是在这种范围内不同的物理定律发挥作用(量子物理学)。接近纳米级的方法有两种:从上而下收缩,或者自下而上发展。“自上而下”的方法需要将结构通过加工和蚀刻技术减小到最小纳米级尺寸,而“自下而上”的方法通常被称为分子纳米技术,意味着控制或定向原子和分子的组合来创建结构3。C.建筑纳米技术 20世纪90年代7初英国的德尔菲调查显示建筑行业是唯一一个确定纳米技术具有广大前景的新兴技术的行业。瑞典和英国建筑报告8-9中也强调了纳米技术的重要性。此外,预制混凝土及混凝土制品被确定为在1015年间可能会受到纳米技术影响的40
5、个行业领域之首6。然而,建筑行业的发展滞后于其他工业部门,由此纳米技术的研究吸引了大型工业企业和风险投资家的浓厚兴趣和投资。意识到纳米技术在建筑行业的巨大潜力和重要性,在2002年年底,欧盟委员会批准拨款给成长工程GMA1-2002-72160”NANOCINEX”?建立一个纳米技术在建筑结构中的卓越贡献的网站。二.纳米技术在土木工程中的应用 由于纳米技术产生的产品具有许多独特的性质,因此纳米技术可用于许多领域的设计和施工过程中。除此之外,这些特性还可以显著的解决当前建设过程中存在的问题,并可能改变建设过程中的要求和组织形式。它的一些详细应用研究如下:A.混凝土 混凝土是一种最常见和广泛使用的
6、建筑材料。纳米技术被用于研究其属性,如水化反应,碱硅酸反应(ASR)和粉煤灰反应2。碱硅酸反应是由于硅质岩水泥和二氧化硅等碱性活骨料的含量引起的。在混凝土配合比中用pozzolona取代部分水泥可以减少ASR孔隙流体的碱度。粉煤灰不仅提高了混凝土的耐久性和强度更 重要的是达到可持续发展的要求,减少了水泥的用量。不过,这种混凝土的固化过程减慢是由于粉煤灰和早期强度的增加,在普通混凝土中也是比较低的。纳米二氧化硅的添加产生致密的微观和纳米结构使机械性能得到了改进。随着部分水泥被添加的纳米二氧化硅所替换,粉煤灰混凝土的密度和强度提高了,尤其是在早期阶段。掺杂大量粉煤灰的混凝土早期可以在纳米尺度上填充
7、大量粉煤灰水泥颗粒之间的孔隙来改善孔径的分布。无定形纳米SiO2的扩散/浆料是用来改善密实混凝土11的抗离析性。添加少量碳纳米管(1%)可以增加抗压和抗折强度1。这也可以改善由硅酸盐水泥和水组成样品的力学性能。氧化多孔碳纳米管(MWNT)的抗压强度(+25N/MM2)和抗弯强度(8N/MM2)相对于未经加强的参考样品有最好的改进。 开裂是许多结构的一个大问题。伊利诺依州Urbana-Champaign大学的分校正在研究愈合聚合物,其中包括微胶囊化的治疗剂和催化化学反应的触发器8。当微胶囊被裂纹破坏时,愈合剂释放到裂纹中与催化剂接触。发生聚合反应粘结裂纹面。自我修复的聚合物特别适合于解决微裂纹的
8、桥墩柱。但它需要昂贵的环氧注射。研究表明,把厌氧微生物(不需要氧气)添加到混凝土搅拌水中在28天内强度增加了25%。希瓦氏菌的微生物的浓度为105个细胞毫升,纳米尺度的观察显示在其表面上有沉积的水泥砂基质。这导致了填充材料在水泥砂基质孔隙中的生长以增加强度。 最后,在今天应用混凝土纤维来增加预制混凝土构件的强度是相当普遍的。在程序中的一大进步是含有纳米二氧化硅粒子和硬化剂的纤维片材(基质)的使用。这些纳米粒子愈合了混凝土表面小的裂缝,并在加强的应用程序中混凝土基质和纤维材料之间的表面形成牢固的键。B.结构复合材料 钢材是一种重要的建筑材料。1992年联邦公路管理局和美国钢铁协会以及美国海军通过
9、将铜纳米颗粒焊接在钢晶体的边界开发了新的,低碳,高性能钢(HPS),具有较高耐腐蚀性主要用于桥梁的建设5。山特维克南澳弗雷斯TM是山特维克南澳弗雷斯材料技术开发的一种新型不锈钢。由于它的高性能,很适合运用于轻巧而又坚固的设计。MMFX2纳米改性钢,美国MFX钢铁公司生产的,具有良好的耐腐蚀性,成形性和耐磨性,可以保持生命周期低成本10.与传统的钢相比。它有一个完全不同的微观结构,类似“夹板”的叠层板条结构。于纳米结构的修改,MMFX钢相比于其他高强度钢具有优异的力学性能,如高强度,韧性和耐疲劳性。这些材料性质可以降低建设成本,在腐蚀环境中的使用寿命更长。MMFX2钢的耐腐蚀性与不锈钢相近,但成
10、本要低得多。因此,MMFX钢已获得认证用在美国的整个一般的建设中C.玻璃 防火玻璃是纳米技术的另一个应用。是通过使用一个膨胀层之间夹持玻璃面板(中间层),形成的二氧化(SiO2)气体纳米颗粒在加热时,变成一个刚性的,不透明的火盾。由于SiO2的疏水性能,可用于防雾涂料或清洁窗户1。纳米SiO2涂层也可以用于防粘建筑外墙的污染物,从而减少设备的维修费用4。D.沥青 膨润土(BT)和有机改性膨润土(OBT)是在应力和剪应力的作用下用来加强和修改通过熔融加工的沥青粘合剂。BT改性沥青具有插层结构而OBT改性沥青具有脱落结构。BT和OBT改性沥青表现出更大的软化点,粘度,较高的复数模量,相对于基质沥青
11、有低相位角,较高的车辙参数和更好的流变性能。但是加入BT和OBT后改性沥青的延展性下降了。同时它们的蠕变劲度有显著的降低。因此,通过加入BT和OBT,低温下的耐龟裂性得到了改善。OBT改性沥青比BT改性沥青具有更好的性能。E.纳米技术在消防中 钢结构的耐火胶凝过程往往是通过厚的涂层,喷上水泥来提高脆弱性和聚合物添加所需的附着力。纳米水泥的研究(纳米颗粒)创造了在这一领域应用的一个新范例。这是通过碳纳米管(CNT)与胶凝材料制造纤维复合材料的混合来实现的,可以继承碳纳米管的高强度等优异性能。聚丙烯纤维被视为一种比传统绝缘法更经济的增加耐火性的方法。碳纳米管因其阻燃性能也可以用来生产防护服装材料。
12、三.纳米技术对建筑的影响A.优点 1)与传统的TiO2相比,纳米TiO2的表面面积增加了500%,不透明度降低了400%。目前纳米TiO2的生产水已达到400万吨平约为45美元/公斤至50美元/公斤,传统的TiO2价格为2.5美元/公斤。 2)全球碳纳米管市场从2006年的5100万美元预计到2011年增长超过8亿美元(BCC)。 3)纳米改性混凝土的施工进度降低了劳动密集型的(昂贵的)工程。此外,可以减少维修和维护成本。 4)油漆和涂料工业年销售额大约为20亿美元(贝尔等.2003)。纳米氧化铝和二氧化钛因其耐磨,韧性和粘结强度特性有46倍的增长(盖尔,2002)。 5)在未来二十年纳米复合
13、材料在全球潜在市场估计为340亿美元(劳卡和邦恩布拉,2001)。 6)2004年的消防系统总额约为45亿美元,预计到2010年将增长到超过800亿美元(赫尔穆特.凯撒,2008)。 7)在基础设施建设材料中嵌入纳米传感器,以最低的成本,充分整合和自供电故障的预测和高资本结构预测机制(例如,水库,核电站,桥梁)。B.缺点 1)由于粒径小,纳米颗粒对呼吸道和消化道、皮肤或眼睛表面具有潜在的负面影响4增加了工人的危害。 2)由于纳米技术相关产业是相对较新的,致力于建筑研究和开发(甚至一些领域的应用)的人员必须有一个跨学科的背景。 3)在纳米技术方面的新政策需要各级政府,研发机构,制造商和其他行业的
14、合作。 4)小批量生产和高成本仍然是纳米技术的主要障碍(皇家社会,2004)。 5)产品商业化时间很长,例如混凝土,可以消除钢筋的需求,商品化预计需要到2020年。四.可持续建筑 水泥行业每年23.5亿万吨的产率为全球的二氧化碳排放量做出了约5%的贡献。已经发现添加剂如钙,钙铝酸盐和钙硫铁铝(巴斯夫,2008)在生产阶段CO2的排放量减少了近25%。由纳米改性混凝土建造的墙在寒冷的天气有可能被用来作为绝热材料,当外界的温度下降或当建筑内部环境温度低时作为导体使用,从而减少了用于调节建筑内部所需的能量负载。随着LED和OLED在绝缘材料和智能玻璃中进一步的技术发展,建筑物满足自己的能源需求将成为
15、现实的愿景。五.纳米技术在建设中未来的投影 跨国公司和风险资本投资投入大量资金在纳米的相关研究上3,5。许多世界级大公司如IBM,英特尔,摩托罗拉,郎讯,波音公司,日立等都有显著的纳米相关研究项目,或推出自己对纳米技术的倡议。美国国家科学基金会估计,到2015年纳米技术对全球经济的影响将有1万亿美元。为了实现市场规模预测这一目标,行业将雇佣近200万个工人致力于对纳米材料,纳米结构和纳米系统的研究。产品的商业化所需要的时间很长,因为企业更喜欢在大量投资之前监测研究机构和实验室的监控开发。此外,纳米技术的发展,特别是与仿生研究的结合将生产更好效率的材料,结构设计和对生产具有真正革命性的方法,可持
16、续性和对环境变化适应能力。六.结论 与建设相关的纳米技术研究仍处于起步阶段;本文定义了纳米技术对施工的影响,论述了主要的优缺点。近年来,纳米技术的研发得到大规模的投资。在纳米相关产品中建筑行业的发展没有的到很好的市场推广,而且对行业专家判断很困难。纳米科学和纳米技术在建筑领域大规模和可行性措施可以帮助种子工程建设相关的纳米技术的发展。把纳米技术在基础设施建设中的及时定向研究列为重点研究对象,确保这项技术的潜在优势被利用,以提供更长的使用寿命和更经济的基础设施。本文总结了一个纳米技术如何最大的影响土木工程领域的路线图和战略行动计划。 参考文献1Mann,S.2006.“纳米技术与建筑,”纳米论坛
17、报告。/0.,2008.5.302Balaguru,P.N,“纳米技术和混凝土:背景,面临的机遇和挑战。”国际会议?技术应用在具体的设计中,苏格兰,英国,p.113-122,2005.3Goddard III, W.A., Brenner, D.W., Lyshevski, S.E. and Iafrate, G.J.“高掺量的纳米SiO2对粉煤灰混凝土性能的影响。”水泥和混凝土的研究,第34卷,p.1043-1049,2004.4 Beatty, C.(2006).“纳米技术降低了沥青的施工温度。”纳米技术研究会,材料科学与工程,国家科学基金会,华盛顿,DC。5美国土木工程师协会。(2005
18、)。“对美国的基础设施报告。美国土木工程师学会”。 “/.6 Baer, D. R., Burrows, P. E., 和 El-Azab, A. A.(2003)。“用纳米技术提高涂层功能的程序。”Prog. Org. Coat., 473?4, 342?356.7 Bartos, P. J. M. 2006.“NANOCONEX路线图新材料。”纳米材料在建筑应用中的重心,毕尔巴鄂,西班牙。“/.8Shah, S. P.,和 A. E. Naaman.“机械性能的玻璃和钢纤维增强砂浆。”ACI杂志73,1期(1976.1):50-53.9Saafi, M. 和 Romine, P. 2005
19、.“纳米和微技术。”国际混凝土,27卷12号,P28-34.10Sobolev, K. 和 Gutierrez, M. F. 2005. “纳米技术如何改变混凝土世界”美国陶瓷学会通报,84卷10号P14-16。11 Lau, Kin-Tak, 和 David Hui.“新型碳纳米管复合材料的革命性创新。”复合材料:B期33,4号(2002):263-277.外文文献: Nanotechnology in Civil EngineeringAbstract The innovation of relevant nanotechnology and its significance in civ
20、il engineering practice is illustrated in this paper for broadening vision. It creates materials, devices, and systems with new properties and functions. The role of nanotechnology in the conceiving of innovative infrastructure systems has the potential to revolutionize the civil engineering practic
21、e and widen the vision of civil engineering. Following this the analysis were carried out in ductile structural composites along with its enhanced properties, low maintenance coatings, better properties of cementitious materials, reducing the thermal transfer rate of fire retardant and insulation, v
22、arious nanosensors, smart materials, intelligent structure technology etc. The properties like self-sensing, self-rehabilitation, self-cleaning, self-vibration damping, self-structural health monitoring and self-healing are the key features. To execute these, the gap between the nanotechnology and c
23、onstruction materials research needs to be bridged. This paper first presents the background information and current developments in nanotechnology and civil engineering in general followed by the merits and demerits of their interdisciplinary approach. Further the details of application oriented na
24、notechnology-enabled materials and products that are either on the market or ready to be adopted in the construction industry and also their possible consequences over the time is elucidated. Some of the major instances of current applications of nanotechnology in the field of civil engineering acro
25、ss its different sections around the globe are exemplified. The most challenging economic factors concerned with its practicality are discussed briefly. Finally the future trend, potential and implications of nanotechnology development in civil engineering towards more economical infrastructure, low
26、 cost maintenance with longer durability are deliberatedKeywords Civil Engineering, Nanomaterials, Nanotechnology, SustainabilityI. IntroductionA. Background As people involved in construction, we are very familiar with the concept of getting raw materials, bringing them together in an organized way
27、 and then putting them together into a recognizable form. The finished product is a passive machine. It works and slowly decays as it is used and abused by the environment and the owners of the project. Construction then is definitely not a new science or technology and yet it has undergone great ch
28、anges over its history. In the same vein, nanotechnology is not a new science and it is not a new technology either. It is rather an extension of the sciences and technologies that have already been in development for many years. The size of the particles is the critical factor. At the nanoscale any
29、thing from one hundred or more down to a few nanometres, or 10-9 m material properties are altered from that of larger scales. Another important aspect is that, as particles become nano-sized, the proportion of atoms on the surface increases relative to those inside and this leads to novel propertie
30、s. It is these “nano-effects”, however, that ultimately determine all the properties that we are familiar with at our “macro-scale” and this is where the power of nanotechnology comes in ? if we can manipulate elements at the nanoscale we can affect the macro-properties and produce significantly new
31、 materials and processes.B. What is NanotechnologyNano, which comes from the Greek word for dwarf. One nanometre is a billionth of a metre. Definitions of nanotechnology vary, but it generally refers to understanding and manipulation of matter on the nanoscale, say, from 0.1 run to 100 nm. The signi
32、ficance and importance of controlling matter at the nanoscale is that at this scale different laws of physics come into play quantum physics; There are two ways to approach the nanoscale: shrinking from the top down, or growing from the bottom up. The top down approach entails reducing the size of t
33、he smallest structures towards the nanoscale by machining and etching techniques, whereas the bottom up approach, often referred to as molecular nanotechnology, implies controlled or directed self-assembly of atoms and molecules to create structures 3.C. Nanotechnology in Construction The constructi
34、on industry was the only industry to identify nanotechnology as a promising emerging technology in the UK Delphi survey in the early 1990s 7. The importance of nanotechnology was also highlighted in foresight reports of Swedish and UK construction 8-9. Furthermore, ready mix concrete and concrete pr
35、oducts were identified as among the top 40 industrial sectors likely to be influenced by nanotechnology in 10-15 years 6. However, construction has lagged behind other industrial sectors where nanotechnology R&D has attracted significant interest and investment from large industrial corporations and
36、 venture capitalists. Recognising the huge potential and importance of nanotechnology to the construction industry, the European Commission in late 2002 approved funding for the Growth Project GMA1-2002-72160 “NANOCONEX” ? Towards the setting up of a Network of Excellence in Nanotechnology in Constr
37、uction.II. Applications of Nanotechnology in Civil Engineering Nanotechnology can be used for design and construction processes in many areas since nanotechnology generated products have many unique characteristics. These characteristics can, again, significantly fix current construction problems, a
38、nd may change the requirement and organization of construction process. Some of its applications are examined in detail below:A. ConcreteConcrete is one of the most common and widely used construction materials. Nanotechnology is widely used in studying its properties like hydration reaction, alkali
39、 silicate reaction ASR and fly ash reactivity 2. Alkali silicate reaction is caused due to alkali content of cement and silica present in reactive aggregates like chert. The use of pozzolona in the concrete mix as a partial cement replacement can reduce the likelihood of ASR occurring as they reduce
40、 the alkalinity of a pore fluid. Fly ash not only improves concrete durability, strength and, importantly for sustainability, reduces the requirement for cement, however, the curing process of such concrete is slowed down due to the addition of fly ash and early stage strength is also low in compari
41、son to normal concreteAddition of Nano-silica leads to the densifying of the micro and nanostructure resulting in improved mechanical properties. With the addition of nano-SiO2?part of the cement is replaced but the density and strength of the fly-ash concrete improves particularly in the early stag
42、es. For concrete containing large volume fly ash, at early age it can improve pore size distribution by filling the pores between large fly ash and cement particles at Nano scale. The dispersion/slurry of amorphous nano-SiO2?is used to improve segregation resistance for self-compacting concrete 26.
43、The addition of small amount of carbon nanotube 1% by weight could increase both compressive and flexural strength 1. This can also improve the mechanical properties of samples consisting of the main portland cement phase and water. Oxidized multi-walled nanotubes MWNTs show the best improvements bo
44、th in compressive strength + 25 N/mm2 and flexural strength +8 N/mm2 compared to the reference samples without the reinforcementCracking is a major concern for many structures. University of Illinois Urbana-Champaign is working on healing polymers, which include a microencapsulated healing agent and
45、 a catalytic chemical trigger 8. When the microcapsules are broken by a crack, the healing agent is released into the crack and contact with the catalyst. The polymerization happens and bond the crack faces. The self-healing polymer could be especially applicable to fix the micro cracking in bridge
46、piers and columns. But it requires costly epoxy injection. Research has shown that an anaerobic one that does not require oxygen microorganism incorporated into concrete mixing water results in a 25% increase in 28-day strength. The Shewanella microorganism was used at a concentration of 105 cells/m
47、l and nanoscale observation revealed that there was a deposition of sand-cement matrix on its surface. This led to the growth of filler material within the pores of the cement sand matrix and resulted in increased strength. Finally, fibre wrapping of concrete is quite common today for increasing the
48、 strength of pre-existing concrete structural elements. An advancement in the procedure involves the use of a fibre sheet matrix containing nano-silica particles and hardeners. These nanoparticles penetrate and close small cracks on the concrete surface and, in strengthening applications, the matrices form a strong bond between the surface of the concrete and the fibre reinforcement.B. Structural CompositesSteel is a major constructio