土木工程專業(yè)畢業(yè)設(shè)計(jì)外文翻譯--土木工程中的納米技術(shù)

1、畢業(yè)設(shè)計(jì)外文文獻(xiàn)翻譯院 系：土木工程與建筑系年級(jí)專業(yè)：2021級(jí)土木工程專業(yè)姓 名：余麗珠學(xué) 號(hào)：0909022214附 件：Nanotechnology in Civil Engineering指導(dǎo)老師評(píng)語： 指導(dǎo)教師簽名：年 月 日中文譯文：土木工程中的納米技術(shù)【摘要】為了拓寬視野，本文對(duì)土木工程中的納米技術(shù)的實(shí)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)備系統(tǒng)。納米技術(shù)在構(gòu)建創(chuàng)新根底設(shè)施系統(tǒng)中的作用對(duì)土木工程的實(shí)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(diǎn)，其次是土木工程一般的背景資料和目前的開展情況。此外，闡述了無論在市場(chǎng)上還是準(zhǔn)備用于建筑行

2、業(yè)的功能導(dǎo)向的納米技術(shù)材料和產(chǎn)品的細(xì)節(jié)以及一定時(shí)間內(nèi)可能導(dǎo)致的后果。列舉了一些目前納米技術(shù)在世界各地不同局部的土木工程領(lǐng)域的應(yīng)用實(shí)例。對(duì)在最具挑戰(zhàn)性的經(jīng)濟(jì)因素下它的實(shí)用性進(jìn)行了簡(jiǎn)要的討論。最后是未來的開展趨勢(shì)，納米技術(shù)的開展對(duì)土木工程向著更經(jīng)濟(jì)的根底設(shè)施，具有較長(zhǎng)使用壽命和低本錢的潛在影響的探討?！娟P(guān)鍵詞】土木工程，納米材料，納米技術(shù)，可持續(xù)開展。一、簡(jiǎn)介A背景 作為建筑行業(yè)的人肯定都對(duì)獲得原材料，把它們組合在一起然后把它們構(gòu)建成一個(gè)可識(shí)別的形式的概念非常熟悉。建筑成品是一個(gè)被動(dòng)的物體。隨著環(huán)境影響和工程業(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

3、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(gè)擴(kuò)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(gè)重要方面是，作為納米尺寸的粒子，在外表上原子的比例相對(duì)于內(nèi)部增加會(huì)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。B什么是納米？納米，希臘文中侏儒的意思。一納米是一米的十億分之一。納米技術(shù)的定義有很多，但一般是指在0.1100nm尺度的空間內(nèi)來研究理解物質(zhì)?？刂圃诩{米尺寸上的

4、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(jí)的方法有兩種：從上而下收縮，或者自下而上開展?！白陨隙碌姆椒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(jí)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)立結(jié)構(gòu)3。C建筑納米技術(shù)20世紀(jì)90年代7初英國(guó)的德爾菲調(diào)查顯示建筑行業(yè)是唯一一個(gè)確定納米技術(shù)具有廣闊前景的新興技術(shù)的行業(yè)。瑞典和英國(guó)建筑報(bào)告8-9中也強(qiáng)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1015年間可能會(huì)受到納米技術(shù)影響的40個(gè)行業(yè)領(lǐng)域之首6。然而，建筑行業(yè)的開展滯后于其他工業(yè)部門，由此納米技術(shù)的研究吸引了大型

5、工業(yè)企業(yè)和風(fēng)險(xiǎn)投資家的濃厚興趣和投資。意識(shí)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(huì)批準(zhǔn)撥款給成長(zhǎng)工程GMA1-2002-72160NANOCINEX建立一個(gè)納米技術(shù)在建筑結(jié)構(gòu)中的卓越奉獻(xiàn)的網(wǎng)站。二納米技術(shù)在土木工程中的應(yīng)用由于納米技術(shù)產(chǎn)生的產(chǎn)品具有許多獨(dú)特的性質(zhì)，因此納米技術(shù)可用于許多領(lǐng)域的設(shè)計(jì)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。它的一些詳細(xì)應(yīng)用研究如下：A混凝土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，如水化反響，堿硅酸反響ASR和粉煤灰反響2。堿硅酸反響是由于硅質(zhì)

6、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取代局部水泥可以減少ASR孔隙流體的堿度。粉煤灰不僅提高了混凝土的耐久性和強(qiáng)度更 重要的是到達(dá)可持續(xù)開展的要求，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(qiáng)度的增加，在普通混凝土中也是比擬低的。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(jī)械性能得到了改良。隨著局部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(qiáng)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(kuò)散/漿料是用來改善密實(shí)混凝土11的抗

7、離析性。添加少量碳納米管1%可以增加抗壓和抗折強(qiáng)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(qiáng)度+25N/MM2和抗彎強(qiáng)度8N/MM2相對(duì)于未經(jīng)加強(qiáng)的參考樣品有最好的改良。開裂是許多結(jié)構(gòu)的一個(gè)大問題。伊利諾依州Urbana-Champaign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)反響的觸發(fā)器8。當(dāng)微膠囊被裂紋破壞時(shí)，愈合劑釋放到裂紋中與催化劑接觸。發(fā)生聚合反響粘結(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。研究說明，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(qiáng)度增加了25%。希瓦氏菌的

8、微生物的濃度為105個(gè)細(xì)胞毫升，納米尺度的觀察顯示在其外表上有沉積的水泥砂基質(zhì)。這導(dǎo)致了填充材料在水泥砂基質(zhì)孔隙中的生長(zhǎng)以增加強(qiáng)度。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(qiáng)度是相當(dāng)普遍的。在程序中的一大進(jìn)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外表小的裂縫，并在加強(qiáng)的應(yīng)用程序中混凝土基質(zhì)和纖維材料之間的外表形成牢固的鍵。鋼材是一種重要的建筑材料。1992年聯(lián)邦公路管理局和美國(guó)鋼鐵協(xié)會(huì)以及美國(guó)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。山特維克南澳弗雷斯TM是山特維克南澳弗雷斯材料技

9、術(shù)開發(fā)的一種新型不銹鋼。由于它的高性能，很適合運(yùn)用于輕巧而又鞏固的設(shè)計(jì)。MMFX2納米改性鋼，美國(guó)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，可以保持生命周期低本錢10.與傳統(tǒng)的鋼相比。它有一個(gè)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(qiáng)度鋼具有優(yōu)異的力學(xué)性能，如高強(qiáng)度，韌性和耐疲勞性。這些材料性質(zhì)可以降低建設(shè)本錢，在腐蝕環(huán)境中的使用壽命更長(zhǎng)。MMFX2鋼的耐腐蝕性與不銹鋼相近，但本錢要低得多。因此，MMFX鋼已獲得認(rèn)證用在美國(guó)的整個(gè)一般的建設(shè)中C玻璃防火玻璃是納米技術(shù)的另一個(gè)應(yīng)用。是通過使用一個(gè)膨脹層之間夾持玻璃面板中間層，形成的二氧

10、化SiO2氣體納米顆粒在加熱時(shí)，變成一個(gè)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(fèi)用4。膨潤(rùn)土BT和有機(jī)改性膨潤(rùn)土OBT是在應(yīng)力和剪應(yīng)力的作用下用來加強(qiáng)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(diǎn)，粘度，較高的復(fù)數(shù)模量，相對(duì)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。但是參加BT和OBT后改性瀝青的延展性下降了。同時(shí)它們的蠕變勁度有顯著的降低。因此，通過參加BT和OBT，低溫下的耐龜裂性得到了改善。OBT改

11、性瀝青比BT改性瀝青具有更好的性能。E納米技術(shù)在消防中鋼結(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(gè)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(shí)現(xiàn)的，可以繼承碳納米管的高強(qiáng)度等優(yōu)異性能。聚丙烯纖維被視為一種比傳統(tǒng)絕緣法更經(jīng)濟(jì)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(hù)服裝材料。三納米技術(shù)對(duì)建筑的影響A優(yōu)點(diǎn)1與傳統(tǒng)的TiO2相比，納米TiO2的外表面積增加了500%，不透明度降低了400%。目前納米TiO2的生產(chǎn)水已到達(dá)400萬噸平約為45美元/公斤至50美元/公斤，傳統(tǒng)的

12、TiO2價(jià)格為2.5美元/公斤。2全球碳納米管市場(chǎng)從2006年的5100萬美元預(yù)計(jì)到2021年增長(zhǎng)超過8億美元BCC。3納米改性混凝土的施工進(jìn)度降低了勞動(dòng)密集型的昂貴的工程。此外，可以減少維修和維護(hù)本錢。4油漆和涂料工業(yè)年銷售額大約為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(qiáng)度特性有46倍的增長(zhǎng)蓋爾，2002。5在未來二十年納米復(fù)合材料在全球潛在市場(chǎng)估計(jì)為340億美元?jiǎng)诳ê桶疃鞑祭?001。62004年的消防系統(tǒng)總額約為45億美元，預(yù)計(jì)到2021年將增長(zhǎng)到超過800億美元赫爾穆特.凱撒，2021。7在根底設(shè)施建設(shè)材料中嵌入納米傳感器，以最低的本錢，充分整合和自供電

13、故障的預(yù)測(cè)和高資本結(jié)構(gòu)預(yù)測(cè)機(jī)制例如，水庫，核電站，橋梁。B缺點(diǎn)1由于粒徑小，納米顆粒對(duì)呼吸道和消化道、皮膚或眼睛外表具有潛在的負(fù)面影響4增加了工人的危害。2由于納米技術(shù)相關(guān)產(chǎn)業(yè)是相對(duì)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(gè)跨學(xué)科的背景。3在納米技術(shù)方面的新政策需要各級(jí)政府，研發(fā)機(jī)構(gòu)，制造商和其他行業(yè)的合作。4小批量生產(chǎn)和高本錢仍然是納米技術(shù)的主要障礙皇家社會(huì)，2004。5產(chǎn)品商業(yè)化時(shí)間很長(zhǎng)，例如混凝土，可以消除鋼筋的需求，商品化預(yù)計(jì)需要到2021年。四可持續(xù)建筑水泥行業(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%的奉獻(xiàn)。已經(jīng)發(fā)現(xiàn)添加劑如鈣，鈣鋁酸鹽和鈣硫鐵鋁

14、巴斯夫，2021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)外界的溫度下降或當(dāng)建筑內(nèi)部環(huán)境溫度低時(shí)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(fù)載。隨著LED和OLED在絕緣材料和智能玻璃中進(jìn)一步的技術(shù)開展，建筑物滿足自己的能源需求將成為現(xiàn)實(shí)的愿景。五納米技術(shù)在建設(shè)中未來的投影跨國(guó)公司和風(fēng)險(xiǎn)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(jí)大公司如IBM，英特爾，摩托羅拉，郎訊，波音公司，日立等都有顯著的納米相關(guān)研究工程，或推出自己對(duì)納米技術(shù)的建議。美國(guó)國(guó)家科學(xué)基金會(huì)估計(jì)，到2021年納米技術(shù)對(duì)全球經(jīng)濟(jì)的影響將有1萬億美元

15、。為了實(shí)現(xiàn)市場(chǎng)規(guī)模預(yù)測(cè)這一目標(biāo)，行業(yè)將雇傭近200萬個(gè)工人致力于對(duì)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(shí)間很長(zhǎng)，因?yàn)槠髽I(yè)更喜歡在大量投資之前監(jiān)測(cè)研究機(jī)構(gòu)和實(shí)驗(yàn)室的監(jiān)控開發(fā)。此外，納米技術(shù)的開展，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(jì)和對(duì)生產(chǎn)具有真正革命性的方法，可持續(xù)性和對(duì)環(huán)境變化適應(yīng)能力。六結(jié)論與建設(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(duì)施工的影響，論述了主要的優(yōu)缺點(diǎn)。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)的開展沒有的到很好的市場(chǎng)推廣，而且對(duì)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

16、子工程建設(shè)相關(guān)的納米技術(shù)的開展。把納米技術(shù)在根底設(shè)施建設(shè)中的及時(shí)定向研究列為重點(diǎn)研究對(duì)象，確保這項(xiàng)技術(shù)的潛在優(yōu)勢(shì)被利用，以提供更長(zhǎng)的使用壽命和更經(jīng)濟(jì)的根底設(shè)施。本文總結(jié)了一個(gè)納米技術(shù)如何最大的影響土木工程領(lǐng)域的路線圖和戰(zhàn)略行動(dòng)方案。參考文獻(xiàn)1Mann,S.(2006).“納米技術(shù)與建筑，納米論壇報(bào)告。2Balaguru,P.N,“納米技術(shù)和混凝土：背景，面臨的機(jī)遇和挑戰(zhàn)。國(guó)際會(huì)議技術(shù)應(yīng)用在具體的設(shè)計(jì)中，蘇格蘭，英國(guó)，p.113-122,2005.3Goddard III, W.A., Brenner, D.W., Lyshevski, S.E. and Iafrate, G.J.“高摻量的納米

17、SiO2對(duì)粉煤灰混凝土性能的影響。水泥和混凝土的研究，第34卷，p.1043-1049,2004.4 Beatty, C.2006.“納米技術(shù)降低了瀝青的施工溫度。納米技術(shù)研究會(huì)，材料科學(xué)與工程，國(guó)家科學(xué)基金會(huì)，華盛頓，DC。5美國(guó)土木工程師協(xié)會(huì)。2005。“對(duì)美國(guó)的根底設(shè)施報(bào)告。美國(guó)土木工程師學(xué)會(huì)。 “ :/ 2021.3.86 Baer, D. R., Burrows, P. E., 和 El-Azab, A. A.2003?！坝眉{米技術(shù)提高涂層功能的程序。Prog. Org. Coat., 47(34), 342356.7 Bartos, P. J. M. (2006).

18、“NANOCONEX路線圖新材料。納米材料在建筑應(yīng)用中的重心，畢爾巴鄂，西班牙。“ :/ mmsconferencing /nanoc/2021.1.138Shah, S. P.,和 A. E. Naaman.“機(jī)械性能的玻璃和鋼纖維增強(qiáng)砂漿。ACI雜志73，1期1976.1:50-53.9Saafi, M. 和 Romine, P. (2005).“納米和微技術(shù)。國(guó)際混凝土，27卷12號(hào)，P28-34.10Sobolev, K. 和 Gutierrez, M. F. (2005). “納米技術(shù)如何改變混凝土世界美國(guó)陶瓷學(xué)會(huì)通報(bào)，84卷10號(hào)P14-16。11 Lau, Kin-Tak, 和

19、David Hui.“新型碳納米管復(fù)合材料的革命性創(chuàng)新。復(fù)合材料：B期33,4號(hào)2002：263-277.外文文獻(xiàn)： Nanotechnology in Civil EngineeringAbstract 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

20、properties and 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 the analysis were carried out in ductile structural composites along

21、 with its enhanced properties, low maintenance coatings, better properties of cementitious materials, reducing the thermal transfer rate of fire retardant and insulation, various nanosensors, smart materials, intelligent structure technology etc. The properties like self-sensing, self-rehabilitation

22、, 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 construction materials research needs to be bridged. This paper first presents the background information and current development

23、s in nanotechnology and civil engineering in general followed by the merits and demerits of their interdisciplinary approach. Further the details of application oriented nanotechnology-enabled materials and products that are either on the market or ready to be adopted in the construction industry an

24、d 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 across its different sections around the globe are exemplified. The most challenging economic factors concerned with its practicalit

25、y are discussed briefly. Finally the future trend, potential and implications of nanotechnology development in civil engineering towards more economical infrastructure, low cost maintenance with longer durability are deliberated. Keywords Civil Engineering, Nanomaterials, Nanotechnology, Sustainabil

26、ity. I. Introduction A. Background 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 finished product is a passive machine. It works and slowly de

27、cays 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 changes over its history.In the same vein, nanotechnology is not a new science and it is not a new technology either. It is r

28、ather 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 (anything from one hundred or more down to a few nanometres, or 10-9 m) material properties are altered from that of larger sca

29、les. 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 properties. It is these “nano-effects, however, that ultimately determine all the properties that we are familiar with at our “macr

30、o-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 materials and processes.B. What is Nanotechnology?  Nano, which comes from the Greek word for dwarf. One nanometre is a

31、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 and importance of controlling matter at the nanoscale is that at this scale different laws of physics come int

32、o 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 the smallest structures towards the nanoscale by machining and etching techniques, whereas the bottom up approach, of

33、ten referred to as molecular nanotechnology, implies controlled or directed self-assembly of atoms and molecules to create structures 3.C. Nanotechnology in Construction The construction industry was the only industry to identify nanotechnology as a promising emerging technology in the UK Delphi sur

34、vey 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 products were identified as among the top 40 industrial sectors likely to be influenced by nanotechnology in 10-15 yea

35、rs 6. However, construction has lagged behind other industrial sectors where nanotechnology R&D has attracted significant interest and investment from large industrial corporations and venture capitalists. Recognising the huge potential and importance of nanotechnology to the construction indust

36、ry, 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 Construction.II. Applications of Nanotechnology in Civil Engineering Nanotechnology can be used for design and constructi

37、on 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 organization of construction process.Some of its applications are examined in det

38、ail below:A. Concrete Concrete is one of the most common and widely used construction 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 ceme

39、nt 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 alkalinity of a pore fluid. Fly ash not only improves concrete durability, strength and, importantly for sus

40、tainability, 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 comparison to normal concrete. Addition of Nano-silica leads to the densifying of the micro and nanostructure resulting

41、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 stages. For concrete containing large volume fly ash, at early age it can improve pore size distribution by fi

42、lling 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. The addition of small amount of carbon nanotube (1%) by weight could increase both compressive and fl

43、exural 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 both in compressive strength (+ 25 N/mm2) and flexural strength (+8 N/mm2) compared to the referenc

44、e samples without the reinforcement. Cracking is a major concern for many structures. University of Illinois Urbana-Champaign is working on healing polymers, which include a microencapsulated healing agent and a catalytic chemical trigger 8. When the microcapsules are broken by a crack, the healing

45、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 piers and columns. But it requires costly epoxy injection. Research has shown that an anaer

46、obic (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/ml and nanoscale observation revealed that there was a deposition of sand-cement matrix on

47、 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 strength of pre-existing concrete structural elements. An advancement in the procedure in

48、volves 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.

49、 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 1992 with higher corrosion-resistance and weld ability by incorporating copper nanopartic

50、les from at the steel grain boundaries 5.Sandvik NanoflexTM is new stainless steel developed by Sandvik Nanoflex 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 kee

51、p life-cycle costs low 10 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 the modified nanostructure, MMFX steel has superior mechanical

52、 properties, e.g. higher strength, ductility and fatigue resistance, over other high-strength steels. These material properties can lead to longer service life in corrosive environments and lower construction costs. The MMFX2 steel has similar corrosion resistance to that of stainless steel, but at

53、a much lower cost. So far, the MMFX steel has gained certification for use in general construction throughout the US.C. Glass  Fire-protective glass is another application of nanotechnology. This is achieved by using a clear intumescent layer sandwiched between glass panels (an interlayer) form

54、ed of fumed silica (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 coatings can also be applied to building exteriors to prevent st

55、icking of pollutants, and thus reduce a facilitysmaintenance costs 4.D. Bitumen   The bentonite (BT) and organically modified bentonite (OBT) were used to reinforce and modify asphalt binder by melt processing under sonication and shearing stresses. The BT modified asphalt possess intercalated

56、structure while OBT modified asphalt possessed exfoliated structure. The BT and OBT modified asphalts have shown greater softening point, viscosity, higher complex modulus, lower phase angle and higher rutting parameter and better rheological properties than the base asphalt. But the ductility of th

57、e modified asphalts decreased with the addition of BT and OBT. They have significantly lower creep stiffness. Therefore, the low temperature cracking resistance was improved by addition ofBT and OBT. The OBT modified asphalts has better properties than the BT modified asphalts.E. Nanotechnology in F

58、ire 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 needed to improve adhesion. However, research into nano-cement (made of nano-sized particles) has