土木工程畢業(yè)設(shè)計外文翻譯--土木工程中的納米技術(shù)

1、<p>　　中文4290字，2615單詞</p><p>　　土木工程中的納米技術(shù)</p><p>　　Fatima Ghani</p><p>　　Member COA,Member IIID,India</p><p>　　摘要：為了拓寬視野，本文對土木工程中的納米技術(shù)的實踐意義和創(chuàng)新作了闡述。它創(chuàng)造了具有新特性和功能的材料設(shè)備

2、系統(tǒng)。納米技術(shù)在構(gòu)建創(chuàng)新基礎(chǔ)設(shè)施系統(tǒng)中的作用對土木工程的實踐和拓寬領(lǐng)域帶來了革命性的改變。本文首先介紹了納米技術(shù)和它們跨學(xué)科應(yīng)用的優(yōu)缺點，其次是土木工程一般的背景資料和目前的發(fā)展情況。此外，闡述了無論在市場上還是準備用于建筑行業(yè)的功能導(dǎo)向的納米技術(shù)材料和產(chǎn)品的細節(jié)以及一定時間內(nèi)可能導(dǎo)致的后果。列舉了一些目前納米技術(shù)在世界各地不同部分的土木工程領(lǐng)域的應(yīng)用實例。對在最具挑戰(zhàn)性的經(jīng)濟因素下它的實用性進行了簡要的討論。最后是未來的發(fā)展趨勢，納米

3、技術(shù)的發(fā)展對土木工程向著更經(jīng)濟的基礎(chǔ)設(shè)施，具有較長使用壽命和低成本的潛在影響的探討。</p><p>　　關(guān)鍵詞：土木工程；納米材料；納米技術(shù)；可持續(xù)發(fā)展</p><p><b>　　1 簡介</b></p><p><b>　　1.1 背景</b></p><p>　　作為建筑行業(yè)的人肯定都對

4、獲得原材料，把它們組合在一起然后把它們構(gòu)建成一個可識別的形式的概念非常熟悉。建筑成品是一個被動的物體。隨著環(huán)境影響和項目業(yè)主的濫用它的功能在慢慢衰退。建筑絕不是一門新的科學(xué)或技術(shù)，但在其歷史上已經(jīng)發(fā)生了很大的變化。同樣，納米技術(shù)也不是一門新的科學(xué)和技術(shù)，而更可以說是一個擴展的科學(xué)和技術(shù)。粒子的大小是關(guān)鍵因素，在納米技術(shù)中（任何事物，從一百或者更多下降到幾納米，或10-9m）大大的改變了材料的特性。另一個重要方面是，作為納米尺寸的粒子，在

5、表面上原子的比例相對于內(nèi)部增加會產(chǎn)生新的屬性。正是這些“納米效應(yīng)”，最終確定了我們所熟悉的“宏觀” 的所有屬性，這正是納米技術(shù)的力量來源—如果我們可以在納米尺寸上操縱元素，那就可以影響其宏觀性質(zhì)，并產(chǎn)生新材料和新工藝。</p><p>　　1.2 什么是納米</p><p>　　納米，希臘文中“侏儒”的意思。一納米是一米的十億分之一?！凹{米技術(shù)”的定義有很多，但一般是指在0.1~100n

6、m尺度的空間內(nèi)來研究理解物質(zhì)?？刂圃诩{米尺寸上的意義與重要性是在這種范圍內(nèi)不同的物理定律發(fā)揮作用（量子物理學(xué)）。接近納米級的方法有兩種：從上而下收縮，或者自下而上發(fā)展?！白陨隙隆钡姆椒ㄐ枰獙⒔Y(jié)構(gòu)通過加工和蝕刻技術(shù)減小到最小納米級尺寸，而“自下而上”的方法通常被稱為分子納米技術(shù)，意味著控制或定向原子和分子的組合來創(chuàng)建結(jié)構(gòu)[3]。</p><p>　　1.3 建筑納米技術(shù)</p><p>

7、　　20世紀90年代初英國的德爾菲調(diào)查顯示建筑行業(yè)是唯一一個確定納米技術(shù)具有廣大前景的新興技術(shù)的行業(yè)。瑞典和英國建筑報告[8-9]中也強調(diào)了納米技術(shù)的重要性。此外，預(yù)制混凝土及混凝土制品被確定為在10~15年間可能會受到納米技術(shù)影響的40個行業(yè)領(lǐng)域之首[6]。然而，建筑行業(yè)的發(fā)展滯后于其他工業(yè)部門，由此納米技術(shù)的研究吸引了大型工業(yè)企業(yè)和風(fēng)險投資家的濃厚興趣和投資。意識到納米技術(shù)在建筑行業(yè)的巨大潛力和重要性，在2002年年底，歐盟委員會批

8、準撥款給成長工程GMA1-2002-72160“NANOCINEX”建立一個納米技術(shù)在建筑結(jié)構(gòu)中的卓越貢獻的網(wǎng)站。</p><p>　　2 納米技術(shù)在土木工程中的應(yīng)用</p><p>　　由于納米技術(shù)產(chǎn)生的產(chǎn)品具有許多獨特的性質(zhì)，因此納米技術(shù)可用于許多領(lǐng)域的設(shè)計和施工過程中。除此之外，這些特性還可以顯著的解決當(dāng)前建設(shè)過程中存在的問題，并可能改變建設(shè)過程中的要求和組織形式。</p&g

9、t;<p>　　它的一些詳細應(yīng)用研究如下：</p><p><b>　　2.1 混凝土</b></p><p>　　混凝土是一種最常見和廣泛使用的建筑材料。納米技術(shù)被用于研究其屬性，如水化反應(yīng)，堿硅酸反應(yīng)（ASR）和粉煤灰反應(yīng)[2]。堿硅酸反應(yīng)是由于硅質(zhì)巖水泥和二氧化硅等堿性活骨料的含量引起的。在混凝土配合比中用pozzolona取代部分水泥可以減少A

10、SR孔隙流體的堿度。粉煤灰不僅提高了混凝土的耐久性和強度更重要的是達到可持續(xù)發(fā)展的要求，減少了水泥的用量。不過，這種混凝土的固化過程減慢是由于粉煤灰和早期強度的增加，在普通混凝土中也是比較低的。</p><p>　　納米二氧化硅的添加產(chǎn)生致密的微觀和納米結(jié)構(gòu)使機械性能得到了改進。隨著部分水泥被添加的納米二氧化硅所替換，粉煤灰混凝土的密度和強度提高了，尤其是在早期階段。摻雜大量粉煤灰的混凝土早期可以在納米尺度上填充

11、大量粉煤灰水泥顆粒之間的孔隙來改善孔徑的分布。無定形納米SiO2的擴散/漿料是用來改善密實混凝土[11]的抗離析性。添加少量碳納米管（1%）可以增加抗壓和抗折強度[1]。這也可以改善由硅酸鹽水泥和水組成樣品的力學(xué)性能。氧化多孔碳納米管（MWNT）的抗壓強度（+25N/MM2）和抗彎強度（8N/MM2）相對于未經(jīng)加強的參考樣品有最好的改進。</p><p>　　開裂是許多結(jié)構(gòu)的一個大問題。伊利諾依州Urbana-C

12、hampaign大學(xué)的分校正在研究愈合聚合物，其中包括微膠囊化的治療劑和催化化學(xué)反應(yīng)的觸發(fā)器[8]。當(dāng)微膠囊被裂紋破壞時，愈合劑釋放到裂紋中與催化劑接觸。發(fā)生聚合反應(yīng)粘結(jié)裂紋面。自我修復(fù)的聚合物特別適合于解決微裂紋的橋墩柱。但它需要昂貴的環(huán)氧注射。研究表明，把厭氧微生物（不需要氧氣）添加到混凝土攪拌水中在28天內(nèi)強度增加了25%。希瓦氏菌的微生物的濃度為105個細胞毫升，納米尺度的觀察顯示在其表面上有沉積的水泥砂基質(zhì)。這導(dǎo)致了填充材料在

13、水泥砂基質(zhì)孔隙中的生長以增加強度。</p><p>　　最后，在今天應(yīng)用混凝土纖維來增加預(yù)制混凝土構(gòu)件的強度是相當(dāng)普遍的。在程序中的一大進步是含有納米二氧化硅粒子和硬化劑的纖維片材（基質(zhì)）的使用。這些納米粒子愈合了混凝土表面小的裂縫，并在加強的應(yīng)用程序中混凝土基質(zhì)和纖維材料之間的表面形成牢固的鍵。</p><p>　　2.2 結(jié)構(gòu)復(fù)合材料</p><p>　　鋼材

14、是一種重要的建筑材料。1992年聯(lián)邦公路管理局和美國鋼鐵協(xié)會以及美國海軍通過將銅納米顆粒焊接在鋼晶體的邊界開發(fā)了新的，低碳，高性能鋼（HPS），具有較高耐腐蝕性主要用于橋梁的建設(shè)[5]。</p><p>　　山特維克南澳弗雷斯TM是山特維克南澳弗雷斯材料技術(shù)開發(fā)的一種新型不銹鋼。由于它的高性能，很適合運用于輕巧而又堅固的設(shè)計。MMFX2納米改性鋼，美國MFX鋼鐵公司生產(chǎn)的，具有良好的耐腐蝕性，成形性和耐磨性，可以

15、保持生命周期低成本[10].與傳統(tǒng)的鋼相比。它有一個完全不同的微觀結(jié)構(gòu)，類似“夾板”的疊層板條結(jié)構(gòu)。于納米結(jié)構(gòu)的修改，MMFX鋼相比于其他高強度鋼具有優(yōu)異的力學(xué)性能，如高強度，韌性和耐疲勞性。這些材料性質(zhì)可以降低建設(shè)成本，在腐蝕環(huán)境中的使用壽命更長。MMFX2鋼的耐腐蝕性與不銹鋼相近，但成本要低得多。因此，MMFX鋼已獲得認證用在美國的整個一般的建設(shè)中。</p><p><b>　　2.3 玻璃<

16、;/b></p><p>　　防火玻璃是納米技術(shù)的另一個應(yīng)用。是通過使用一個膨脹層之間夾持玻璃面板（中間層），形成的二氧化（SiO2）氣體納米顆粒在加熱時，變成一個剛性的，不透明的火盾。由于SiO2的疏水性能，可用于防霧涂料或清潔窗戶[1]。納米SiO2涂層也可以用于防粘建筑外墻的污染物，從而減少設(shè)備的維修費用[4]。</p><p><b>　　2.4 瀝青</b&

17、gt;</p><p>　　膨潤土（BT）和有機改性膨潤土（OBT）是在應(yīng)力和剪應(yīng)力的作用下用來加強和修改通過熔融加工的瀝青粘合劑。BT改性瀝青具有插層結(jié)構(gòu)而OBT改性瀝青具有脫落結(jié)構(gòu)。BT和OBT改性瀝青表現(xiàn)出更大的軟化點，粘度，較高的復(fù)數(shù)模量，相對于基質(zhì)瀝青有低相位角，較高的車轍參數(shù)和更好的流變性能。但是加入BT和OBT后改性瀝青的延展性下降了。同時它們的蠕變勁度有顯著的降低。因此，通過加入BT和OBT，低溫

18、下的耐龜裂性得到了改善。OBT改性瀝青比BT改性瀝青具有更好的性能。</p><p>　　2.5 納米技術(shù)在消防中</p><p>　　鋼結(jié)構(gòu)的耐火膠凝過程往往是通過厚的涂層，噴上水泥來提高脆弱性和聚合物添加所需的附著力。納米水泥的研究（納米顆粒）創(chuàng)造了在這一領(lǐng)域應(yīng)用的一個新范例。這是通過碳納米管（CNT）與膠凝材料制造纖維復(fù)合材料的混合來實現(xiàn)的，可以繼承碳納米管的高強度等優(yōu)異性能。聚丙烯

19、纖維被視為一種比傳統(tǒng)絕緣法更經(jīng)濟的增加耐火性的方法。碳納米管因其阻燃性能也可以用來生產(chǎn)防護服裝材料。</p><p>　　3 納米技術(shù)對建筑的影響</p><p><b>　　3.1 優(yōu)點</b></p><p>　?。?)與傳統(tǒng)的TiO2相比，納米TiO2的表面面積增加了500%，不透明度降低了400%。目前納米TiO2的生產(chǎn)水已達到40

20、0萬噸平約為45美元/公斤至50美元/公斤，傳統(tǒng)的TiO2價格為2.5美元/公斤。</p><p>　?。?）全球碳納米管市場從2006年的5100萬美元預(yù)計到2011年增長超過8億美元（BCC）。</p><p>　　（3）納米改性混凝土的施工進度降低了勞動密集型的（昂貴的）工程。此外，可以減少維修和維護成本。</p><p>　　（4）油漆和涂料工業(yè)年銷售額大約

21、為20億美元（貝爾等.2003）。納米氧化鋁和二氧化鈦因其耐磨，韌性和粘結(jié)強度特性有4~6倍的增長（蓋爾，2002）。</p><p>　?。?）在未來二十年納米復(fù)合材料在全球潛在市場估計為340億美元（勞卡和邦恩布拉，2001）。</p><p>　　（6）2004年的消防系統(tǒng)總額約為45億美元，預(yù)計到2010年將增長到超過800億美元（赫爾穆特.凱撒，2008）。</p>

22、<p>　?。?）在基礎(chǔ)設(shè)施建設(shè)材料中嵌入納米傳感器，以最低的成本，充分整合和自供電故障的預(yù)測和高資本結(jié)構(gòu)預(yù)測機制（例如，水庫，核電站，橋梁）。</p><p><b>　　3.2 缺點</b></p><p>　　（1）由于粒徑小，納米顆粒對呼吸道和消化道、皮膚或眼睛表面具有潛在的負面影響[4]增加了工人的危害。</p><p>

23、;　　（2）由于納米技術(shù)相關(guān)產(chǎn)業(yè)是相對較新的，致力于建筑研究和開發(fā)（甚至一些領(lǐng)域的應(yīng)用）的人員必須有一個跨學(xué)科的背景。</p><p>　?。?）在納米技術(shù)方面的新政策需要各級政府，研發(fā)機構(gòu)，制造商和其他行業(yè)的合作。</p><p>　?。?）小批量生產(chǎn)和高成本仍然是納米技術(shù)的主要障礙（皇家社會，2004）。</p><p>　　（5）產(chǎn)品商業(yè)化時間很長，例如混凝土

24、，可以消除鋼筋的需求，商品化預(yù)計需要到2020年。</p><p><b>　　4 可持續(xù)建筑</b></p><p>　　水泥行業(yè)每年23.5億萬噸的產(chǎn)率為全球的二氧化碳排放量做出了約5%的貢獻。已經(jīng)發(fā)現(xiàn)添加劑如鈣，鈣鋁酸鹽和鈣硫鐵鋁（巴斯夫，2008）在生產(chǎn)階段CO2的排放量減少了近25%。由納米改性混凝土建造的墻在寒冷的天氣有可能被用來作為絕熱材料，當(dāng)外界的溫

25、度下降或當(dāng)建筑內(nèi)部環(huán)境溫度低時作為導(dǎo)體使用，從而減少了用于調(diào)節(jié)建筑內(nèi)部所需的能量負載。隨著LED和OLED在絕緣材料和智能玻璃中進一步的技術(shù)發(fā)展，建筑物滿足自己的能源需求將成為現(xiàn)實的愿景。</p><p>　　5 納米技術(shù)在未來建設(shè)中的投影</p><p>　　跨國公司和風(fēng)險資本投資投入大量資金在納米的相關(guān)研究上[3,5]。許多世界級大公司如IBM，英特爾，摩托羅拉，郎訊，波音公司，日立

26、等都有顯著的納米相關(guān)研究項目，或推出自己對納米技術(shù)的倡議。美國國家科學(xué)基金會估計，到2015年納米技術(shù)對全球經(jīng)濟的影響將有1萬億美元。為了實現(xiàn)市場規(guī)模預(yù)測這一目標，行業(yè)將雇傭近200萬個工人致力于對納米材料，納米結(jié)構(gòu)和納米系統(tǒng)的研究。產(chǎn)品的商業(yè)化所需要的時間很長，因為企業(yè)更喜歡在大量投資之前監(jiān)測研究機構(gòu)和實驗室的監(jiān)控開發(fā)。此外，納米技術(shù)的發(fā)展，特別是與仿生研究的結(jié)合將生產(chǎn)更好效率的材料，結(jié)構(gòu)設(shè)計和對生產(chǎn)具有真正革命性的方法，可持續(xù)性和對

27、環(huán)境變化適應(yīng)能力。</p><p><b>　　6 結(jié)論</b></p><p>　　與建設(shè)相關(guān)的納米技術(shù)研究仍處于起步階段,本文定義了納米技術(shù)對施工的影響，論述了主要的優(yōu)缺點。近年來，納米技術(shù)的研發(fā)得到大規(guī)模的投資。在納米相關(guān)產(chǎn)品中建筑行業(yè)的發(fā)展沒有的到很好的市場推廣，而且對行業(yè)專家判斷很困難。納米科學(xué)和納米技術(shù)在建筑領(lǐng)域大規(guī)模和可行性措施可以幫助種子工程建設(shè)相關(guān)

28、的納米技術(shù)的發(fā)展。把納米技術(shù)在基礎(chǔ)設(shè)施建設(shè)中的及時定向研究列為重點研究對象，確保這項技術(shù)的潛在優(yōu)勢被利用，以提供更長的使用壽命和更經(jīng)濟的基礎(chǔ)設(shè)施。</p><p><b>　　參考文獻</b></p><p>　　[1] Mann, S. (2006). “Nanotechnology and Construction,” Nanoforum Report. www

29、.nanoforum.org, May 30, 2008.</p><p>　　[2] Balaguru, P. N., “Nanotechnology and Concrete: Background, Opportunities and Challenges.” Proceedings of the International Conference – Application of Technology i

30、n Concrete Design[J].2005:113-122.</p><p>　　[3] Goddard III, W.A., Brenner, D.W., Lyshevski, S.E. and Iafrate, G.J. “Properties of High-Volume Fly Ash Concrete Incorporating Nano-SiO2.” Cement and Concrete

31、Research[J].2004: 143-149.</p><p>　　[4] Beatty, C. (2006). “Nanomodification of asphalt to lower construction temperatures.” NSF Workshop on Nanotechnology, Material Science and Engineering, National Scienc

32、e Foundation, Washington, DC.</p><p>　　[5] ASCE. (2005). “Report card for America’s infrastructure. American society of civil engineers” “http://www.asce.org”(Mar. 8, 2008).</p><p>　　[6] Baer,

33、 D. R., Burrows, P. E., and El-Azab, A. A. (2003). “Enhancing coating functionality using nanoscience and nanotechnology.” Prog. Org. Coat. [J].2003, 47(3–4):342–356.</p><p>　　[7] Bartos, P. J. M. (2006). “

34、NANOCONEX Roadmap-novel materials.” Centre for Nanomaterials Applications in Construction, Bilbao, Spain “http://www.mmsconferencing.com/nanoc/” (Jan. 13, 2008).</p><p>　　[8] Shah, S. P., and A. E. Naaman.

35、“Mechanical Properties of Glass and Steel Fiber Reinforced Mortar.” ACI Journal 73[J].1996 ,(1): 50-53.</p><p>　　[9] Saafi, M. and Romine, P. (2005).”Nano- and Microtechnology.” Concrete International[J].20

36、05, (12):28-34.</p><p>　　[10] Sobolev, K. and Gutierrez, M. F. (2005). “How Nanotechnology can Change the Concrete World,” American Ceramic Society Bulletin[J]. 2005, (10):14-16.</p><p>　　[11]

37、 Lau, Kin-Tak, and David Hui. “The revolutionary creation of new advanced materials—carbon nanotube composites.” Composites[J].2002,Part B 33, no. 4: 263-277.</p><p>　　From Fatima Ghani. “Nanotechnology and

38、 Construction,” Nanoforum Report[J]. May 30, 2008.</p><p>　　NANOTECHNOLOGY IN CIVIL ENGINEERING</p><p>　　Fatima Ghani,</p><p>　　Member COA,Member IIID, India</p><p>　　A

39、bstract: The innovation of relevant nanotechnology and its significance in civil engineering practice is illustrated in this paper for broadening vision. It creates materials, devices, and systems with new properties and

40、 functions. The role of nanotechnology in the conceiving of innovative infrastructure systems has the potential to revolutionize the civil engineering practice and widen the vision of civil engineering. Following this th

41、e analysis were carried out in ductile structural composite</p><p>　　Key Words: Civil Engineering;Nanomaterials;Nanotechnology;Sustainability</p><p>　　1 Introduction 1.1 Background </p&g

42、t;<p>　　As people involved in construction, we are very familiar with the concept of getting raw materials, bringing them together in an organized way and then putting them together into a recognizable form. The f

43、inished 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 u

44、ndergone great changes over its history.</p><p>　　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

45、have already been in development for many years. The size of the particles is the critical factor. At the nanoscale (anything from one hundred or more down to a few nanometres, or 10-9 m) material properties are altered

46、from that of larger scales. Another important aspect is that, as particles become nano-sized, the proportion of atoms on th</p><p>　　1.2 What is Nanotechnology Nano, which comes from the Greek word for

47、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 significance an

48、d 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 dow</p>&l

49、t;p>　　1.3 Nanotechnology in Construction The construction industry was the only industry to identify nanotechnology as a promising emerging technology in the UK Delphi survey in the early 1990s [7]. The importan

50、ce of nanotechnology was also highlighted in foresight reports of Swedish and UK construction [8-9]. Furthermore, ready mix concrete and concrete products were identified as among the top 40 industrial sectors likely to

51、be influenced by nanotechnology in 10-15 years [6]. However, construc</p><p>　　2 Applications of Nanotechnology in Civil Engineering </p><p>　　Nanotechnology can be used for design and construc

52、tion processes in many areas since nanotechnology generated products have many unique characteristics. These characteristics can, again, significantly fix current construction problems, and may change the requirement and

53、 organization of construction process.</p><p>　　Some of its applications are examined in detail below:</p><p>　　2.1 Concrete Concrete is one of the most common and widely used construction

54、 materials. Nanotechnology is widely used in studying its properties like hydration reaction, alkali silicate reaction (ASR) and fly ash reactivity [2]. Alkali silicate reaction is caused due to alkali content of cement

55、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 the alkalinit</p><p>　

56、　Addition 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

57、 of the fly-ash concrete improves particularly in the early stages. 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 p

58、articles at Nano scale. The dispersion/slurry of amorphous nano-Si</p><p>　　Cracking is a major concern for many structures. University of Illinois Urbana-Champaign is working on healing polymers, which incl

59、ude a microencapsulated healing agent and 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 hap

60、pens and bond the crack faces. The self-healing polymer could be especially applicable to fix the micro cracking in bridge piers and columns. But it </p><p>　　Finally, fibre wrapping of concrete is quite com

61、mon today for increasing the 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 nanopar

62、ticles 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.</p><p>　　2

63、.2 Structural Composites  Steel is a major construction material. FHWA together with American Iron and Steel Institute and the U.S. Navy developed new, low carbon, high-performance steel (HPS) for bridges in 19

64、92 with higher corrosion-resistance and weld ability by incorporating copper nanoparticles from at the steel grain boundaries [5].</p><p>　　Sandvik NanoflexTM is new stainless steel developed by Sandvik Nano

65、flex Materials Technology. Due to its high performance, it is suitable for application which requires lightweight and rigid designs. Its good corrosion, formability and wear resistance can keep life-cycle costs low [10]

66、MMFX2 is nanostructure-modified steel, produced by MFX Steel Corp, USA. Compared with the conventional steel, it has a fundamentally different microstructure- laminated lath structure resembling “plywood”. Due to </p&

67、gt;<p>　　2.3 Glass  Fire-protective glass is another application of nanotechnology. This is achieved by using a clear intumescent layer sandwiched between glass panels (an interlayer) formed of fumed sil

68、ica (SiO2) nanoparticles which turns into a rigid and opaque fire shield when heated. Because of the hydrophobic properties of TiO2, it can be applied in antifogging coatings or in self-cleaning windows [1]. Nano-TiO2

69、60;coatings can also be applied to building exteriors to prevent sticking of pollutant</p><p>　　2.4 Bitumen   The bentonite (BT)and organically modified bentonite (OBT)were used to reinforce and m

70、odify asphalt binder by melt processing under sonication and shearing stresses. The BT modified asphalt possess intercalated structure while OBT modified asphalt possessed exfoliated structure. The BT and OBT modified as

71、phalts have shown greater softening point, viscosity, higher complex modulus, lower phase angle and higher rutting parameter and better rheological properties than the base a</p><p>　　2.5 Nanotechnology in

72、Fire Protection Fire resistance of steel structures is often provided by a coating of spray on cementitious process which is no more popular because they need to be thick, tend to be brittle and polymer additions are

73、 needed to improve adhesion. However, research into nano-cement (made of nano-sized particles) has the potential to create a new paradigm in this area of application. This is achieved by the mixing of carbon nanotubes (C

74、NT’s) with the cementious material to</p><p>　　3 Impacts of Nanotechnology on Construction 3.1 Merits   (1) Compared with conventional TiO2, TiO2 at the nano-scale experiences a 500% increa

75、se in surface area and a 400% decrease in opacity. Current nano-TiO2 production levels have reached approximately 4 million metric tons at a price of approximately $45/kg to $50/kg vs. $2.5/kg for conventional TiO2.

76、</p><p>　　(2) The CNT market worldwide is expected to grow from $51 million in 2006 to more than $800 million by 2011 (BCC Research 2008).</p><p>　　(3) Nano-modified concrete cuts down construct

77、ion schedules while reducing labour-intensive (and expensive) tasks. Also it can reduce the cost of repair and maintenance.</p><p>　　(4) The paint and coatings industry consists of approximately annual sales

78、 of $20 billion (Baer et al. 2003). Nano-alumina and titania have a four- to six-fold increase in wear resistance, with doubled toughness and bond strength (Gell 2002).</p><p>　　(5) The potential global mark

79、et of nanocomposites is estimated at $340 billion for the next two decades (Roco and Bainbridge 2001).</p><p>　　(6) The market for fire protection systems totalled approximately $45 billion in 2004 and is ex

80、pected to grow to more than $80 billion by 2010 (Helmut Kaiser Consultancy 2008).</p><p>　　(7) Nano sensors embedded in infrastructural materials can provide, at minimum cost, fully integrated and self-power

81、ed failure prediction and forecasting mechanisms for high-capital structures (e.g., reservoirs, nuclear power plants, and bridges).</p><p>　　3.2 Demerits   (1) Because of their small particle size,

82、 nano particles have the potential to negatively affect the respiratory and digestive tracks and the skin or eye surface [3] thus exposes workers to hazards.</p><p>　　(2) Since nanotechnology-related industr

83、ies are relatively new, the type of worker who is employed in construction research and development (or even some field applications) must have an interdisciplinary background.</p><p>　　(3) New policies in t

84、he context of nanotechnology will require cooperation between various levels of government, R&D agencies, manufacturers, and other industries.</p><p>　　(4) Small production volumes and high cost remain t

85、he main barriers to the use of nanotechnology (The Royal Society 2004).</p><p>　　(5) The time for commercializing a product is long. E.g. the concrete, which can eliminate the need for reinforcing bars, is p

86、rojected to be commercialized by approximately 2020.</p><p>　　4 Sustainable Construction At an annual production rate of 2.35 billion tons, the cement industry contributes about 5% to global anthropoge

87、nic CO2emissions. Additives such as belite, calcium sulfo-aluminate and calcium alumino-ferrite (BASF 2008) have been found to reduce the CO2 emissions by nearly 25% in the production phase.</p><p>　　A

88、wall made of nano-modified concrete during a cold weather season could potentially be used as a thermal insulator when the outside temperature falls or used as a conductor when the ambient temperature inside the building

89、 is low, thereby reducing the energy load required for conditioning the building interior.</p><p>　　With further development of LED & OLED technology and progress in the insulating materials and smart gl

90、azing, the vision for buildings to meet their own energy requirement will become a reality.</p><p>　　5 Future Projection of Nanotechnology in Construction There is substantial money flowing into nano-r

91、elated research from multinational corporations and venture capital investments [3, 5]. Many of the world’s largest companies such as IBM, Intel, Motorola, Lucent, Boeing, Hitachi, etc. have all had significant Nano-rela

92、ted research projects going on, or launched their own nanotech initiatives. By 2015, the National Science Foundation estimates that nanotechnology will have a $1 trillion eff</p><p>　　6 Conclusion</p>

93、<p>　　Research in nanotechnology that is related to construction is still in its infancy, however, this paper has demonstrated the main benefits and barriers that allow the effect of nanotechnology on construction

94、 to be defined. Recent years of R&D have shown massive investments Nano-construction. The activities in Nano related products for the construction industry are not well marketed and are difficult for industry experts

95、 to identify. A large-scale and visible initiative from nano-science and nano</p><p>　　References</p><p>　　[1] Mann, S. (2006). “Nanotechnology and Construction,” Nanoforum Report. www.nanoforu

96、m.org, May 30, 2008.</p><p>　　[2] Balaguru, P. N., “Nanotechnology and Concrete: Background, Opportunities and Challenges.” Proceedings of the International Conference – Application of Technology in Concret

97、e Design[J].2005:113-122.</p><p>　　[3] Goddard III, W.A., Brenner, D.W., Lyshevski, S.E. and Iafrate, G.J. “Properties of High-Volume Fly Ash Concrete Incorporating Nano-SiO2.” Cement and Concrete Research[

98、J].2004: 143-149.</p><p>　　[4] Beatty, C. (2006). “Nanomodification of asphalt to lower construction temperatures.” NSF Workshop on Nanotechnology, Material Science and Engineering, National Science Foundat

99、ion, Washington, DC.</p><p>　　[5] ASCE. (2005). “Report card for America’s infrastructure. American society of civil engineers” “http://www.asce.org”(Mar. 8, 2008).</p><p>　　[6] Baer, D. R., B

100、urrows, P. E., and El-Azab, A. A. (2003). “Enhancing coating functionality using nanoscience and nanotechnology.” Prog. Org. Coat. [J].2003, 47(3–4):342–356.</p><p>　　[7] Bartos, P. J. M. (2006). “NANOCONEX