混凝土方面畢業(yè)論文外文翻譯--在混凝土的修復(fù)過程中的腐蝕抑制劑和其他保護(hù)系統(tǒng)

1、<p>　　本科畢業(yè)設(shè)計(jì)（論文）外文翻譯譯文</p><p>　　學(xué)生姓名： </p><p>　　院 （系）： </p><p>　　專業(yè)班級： </p><p>　　

2、指導(dǎo)教師： </p><p>　　完成日期： 年 月 日 </p><p><b>　　要 求</b></p><p>　　1、外文翻譯是畢業(yè)設(shè)計(jì)（論文）的主要內(nèi)容之一，必須學(xué)生獨(dú)立完成。</p><p>　　2、外文翻譯譯文內(nèi)容

3、應(yīng)與學(xué)生的專業(yè)或畢業(yè)設(shè)計(jì)（論文）內(nèi)容相關(guān)，不得少于15000印刷符號。</p><p>　　3.外文翻譯譯文用A4紙打印。文章標(biāo)題用3號宋體，章節(jié)標(biāo)題用4號宋體，正文用小4號宋體，20磅行距；頁邊距上、下、左、右均為2.5cm，左側(cè)裝訂，裝訂線0.5cm。按中文翻譯在上，外文原文在下的順序裝訂。</p><p>　　4、年月日等的填寫，用阿拉伯?dāng)?shù)字書寫，要符合《關(guān)于出版物上數(shù)字用法的試行規(guī)

4、定》，如“2005年2月26日”。</p><p>　　5、所有簽名必須手寫，不得打印。</p><p><b>　　文獻(xiàn)名稱</b></p><p>　　在混凝土的修復(fù)過程中的腐蝕抑制劑和其他保護(hù)系統(tǒng)：真正的理解或者誤解</p><p><b>　　文獻(xiàn)名稱</b></p><

5、p>　　Corrosion inhibitors and other protective systems in concrete repair: concepts or misconcepts</p><p>　　作者：R.Dhanaraj</p><p>　　起止頁碼：168-172</p><p>　　出版日期（期刊號）：ISBN 7-5608-2492

6、-7</p><p>　　出版單位：Dept. of Civil Engg. Crescent Engg. College, India.</p><p><b>　　外文翻譯譯文：</b></p><p>　　在混凝土的修復(fù)過程中的腐蝕抑制劑和其他保護(hù)系統(tǒng)： 真正的理解或者誤解</p><p>　　在最近的一段時(shí)間內(nèi)，

7、在世界的很多地方，早期鋼筋的腐蝕而對混凝土結(jié)構(gòu)產(chǎn)生的早期惡化和損壞，已經(jīng)成為混凝土結(jié)構(gòu)方面的主要問題。加速這個(gè)惡化過程的一個(gè)主要因素是混凝土結(jié)構(gòu)所存在的環(huán)境和氣候狀況。惡劣的環(huán)境與低質(zhì)量的混凝土加上有或無缺陷的設(shè)計(jì)和建設(shè)慣例，這都使結(jié)構(gòu)惡化的過程變得具有交互性，累積得非常迅速，進(jìn)而形成一種惡性的發(fā)展，而且很難被停止。很多混凝土結(jié)構(gòu)耐久性差的性能正引起結(jié)構(gòu)產(chǎn)生裂縫.而在補(bǔ)救工作的支出，則使物主和社會(huì)所不能承擔(dān)，并且他們也不希望看到悲劇重演

8、。這篇文章僅提出一些對鋼筋腐蝕和保護(hù)選擇的初步認(rèn)識，而對混凝土和混凝土修理的抑制混合物腐蝕的影響則進(jìn)行了詳細(xì)討論。與抑制劑在修理效力有關(guān)的復(fù)雜論文已經(jīng)發(fā)表，其中主要對基于電化學(xué)活動(dòng)在新結(jié)構(gòu)和修復(fù)結(jié)構(gòu)方面之間差別進(jìn)行了分析。隨著盲目的對需要修理的混凝土使用那些適用于新建筑的保護(hù)方法，文章斷定："修復(fù)混凝土"的生意將會(huì)越來越好。一種對新的和需要修理的混凝土之間的電化學(xué)差別的更廣泛理解認(rèn)為對修理的結(jié)構(gòu)使用有效的鋼筋保護(hù)是必

9、要的。</p><p><b>　　1.序言</b></p><p>　　這是一個(gè)不幸的事實(shí)。全世界范圍內(nèi),大量混凝土結(jié)構(gòu)都處在惡化/ 危險(xiǎn)狀態(tài)的階段。同時(shí)，必須承認(rèn)的是，很多被修理的混凝土結(jié)構(gòu)在幾年后，一修再修。被修理混凝土結(jié)構(gòu)的保持性能的長久表現(xiàn)則最大限度的取決于它們的設(shè)計(jì)，建設(shè)，維護(hù)和使用。與建筑在修理的幾年之后出現(xiàn)裂縫相比，幾乎沒有問題能加劇公眾與政府之間的沖

10、突，并且導(dǎo)致他們對我們提供的建筑物用途的功能感到不滿意。然而與預(yù)期相反，不管是惡劣的環(huán)境狀況還是適合的環(huán)境狀態(tài),在混凝土修理過程中,腐蝕的問題已經(jīng)變得非常普遍.</p><p>　　因而，混凝土修理業(yè)正面臨一項(xiàng)主要的挑戰(zhàn)： 怎樣制止全世界物質(zhì)基礎(chǔ)設(shè)施的腐壞。它是如此重要，對當(dāng)今的混凝土修復(fù)，我們要迫切檢查腐蝕和腐蝕保護(hù)措施的發(fā)行，且探索在不久的將來它有可能改進(jìn)的地方， 即：如何使現(xiàn)在的修理能耐用到將來。一種用于修

11、理結(jié)構(gòu)的,對導(dǎo)致過早腐蝕過程的基本理解仍然沒有涉及混凝土的修理單元。而它不僅應(yīng)用于修復(fù)結(jié)構(gòu)鋼筋銹蝕的過程和混凝土的惡化腐蝕過程， 而且也被應(yīng)用于多種被提議的溶液腐蝕保護(hù)技術(shù)，材料和系統(tǒng)。他們應(yīng)用實(shí)際的歷史非常悠久，但它們在許多案例中的表現(xiàn)是可疑的。</p><p>　　在混凝土修復(fù)過程中的鋼筋腐蝕和保護(hù)的范圍內(nèi)，這篇文章提出了一些隨機(jī)想法。本文圍繞修理過程中鋼的腐蝕的基本過程，闡明了與電化學(xué)性質(zhì)相反的原理，講述了

12、這些過程怎樣導(dǎo)致合成修理系統(tǒng)的最后失敗的道理。為了延長混凝土結(jié)構(gòu)的使用壽命,文章也敘述了我們能或者不能成功解決這幾個(gè)問題的方法。終究，我們必須從繁忙的工作表中周期性地抽身出來，回顧一下,我們在哪里和我們可能將要去哪里。當(dāng)然，在這篇文章里，有一些想法可能會(huì)引起其它人同意或者不同意的意見。但是只有當(dāng)想法得到爭論時(shí)，才可能取得進(jìn)步，并且這也是本篇文章的目的。</p><p>　　在這里提供關(guān)于腐蝕和保護(hù)問題各方面的重要

13、評論是不可能的.那些問題相對于本篇中的某個(gè)的重要討論來說太廣泛，而且各種各樣的結(jié)構(gòu)過于復(fù)雜。關(guān)于混凝土中鋼筋腐蝕和保護(hù)的一般問題,許多作者已經(jīng)詳細(xì)闡述過，在這里就不再敖述了。</p><p>　　研究已經(jīng)實(shí)質(zhì)上改進(jìn)了我們對水泥材料的認(rèn)識， 碳酸飽和引起腐蝕式的混凝土消耗，氯化物引起腐蝕的理論：硫酸鹽侵蝕，堿類聚合反應(yīng)，嚴(yán)寒等等。但是，由于在混凝土的修補(bǔ)過程中鋼筋的嚴(yán)重腐蝕和惡劣自然環(huán)境中的修復(fù)和修復(fù)失敗，使得修補(bǔ)

14、工業(yè)發(fā)展的如此緩慢，這或許可歸因于下列綜合因素：</p><p>　　混凝土修補(bǔ)是一種非常復(fù)雜的系統(tǒng)。它要暴露在外部環(huán)境和內(nèi)部的環(huán)境，并受到環(huán)境間的相互作用。</p><p>　　目前，提出腐蝕問題的基本原理指導(dǎo)還未發(fā)表。在復(fù)雜的修理環(huán)境中，鈍化的裝置和鋼鐵的腐蝕不被人了解。整個(gè)區(qū)域中，現(xiàn)在關(guān)于修理中鋼筋的附加保護(hù)問題得到了大家的廣泛關(guān)注。</p><p>　　預(yù)埋

15、入水泥中的鋼筋的腐蝕是種極其復(fù)雜的現(xiàn)象，這種現(xiàn)象的形成涉及到環(huán)境學(xué)，冶金學(xué)，分界面和連續(xù)統(tǒng)一體等因素。此領(lǐng)域中的大多數(shù)學(xué)術(shù)研究，對于工人來說沒有足夠?qū)I(yè)知識來處理，已經(jīng)由國家工程高校組織力量集中解決。</p><p>　　得到支持的行業(yè)和政府代表展現(xiàn)了對于解決問題的決心。真正的過程不是以學(xué)者在倉促時(shí)間內(nèi)的工作做為基礎(chǔ)。項(xiàng)目的啟動(dòng)，必須需要科學(xué)的可執(zhí)行計(jì)劃和充足的資金做為基礎(chǔ)。</p><p&g

16、t;　　一個(gè)烏托邦夢想存在，是因?yàn)閱栴}可能被藉由使用高性能的材料，防腐劑，保護(hù)材料等等或者安全帶和懸掛系統(tǒng)等措施來解決。這使得在工地上許多工人忽略了混凝土技術(shù)的基本要素和其他基本水泥材料。</p><p>　　要設(shè)計(jì)耐用修理的知識在馬瑟 [1]的著作"完全精煉說明"里已經(jīng)敘述， 但是這種使用此知識的方式是第一次。</p><p>　　一些在修理領(lǐng)域內(nèi)的研究已經(jīng)涉及到修理

17、材料和他們與現(xiàn)有實(shí)體有關(guān)的空間行為特性的改進(jìn)。但是只要電化學(xué)的兼容性的問題也考慮解決，這些活動(dòng)將產(chǎn)生在修理耐久性方面的改進(jìn)。惡化混凝土的去除和它的修理材料的替代品，即使與最好的一種一起替換，也可能由于宏單元的形成而加速鋼筋腐蝕。</p><p>　　這篇文章的主題致力于解決若干令人困惑的議題，并且試圖從混凝土修理過程中的過早腐蝕問題建立關(guān)于鋼筋保護(hù)的事實(shí)，特別是提出關(guān)于防腐材料的問題。</p>&l

18、t;p>　　我們怎樣能期望被修理的混凝土結(jié)構(gòu)是耐用的呢？如果測驗(yàn)方法，腐蝕保護(hù)方法的設(shè)計(jì)和說明都不可靠，難道依賴在修理系統(tǒng)里的電化學(xué)類似于那在"新建筑"里發(fā)生的不適當(dāng)?shù)募俣▎幔啃蘩砉ぷ骱托陆ㄖ兄匾牟煌?，不同因素?jīng)常導(dǎo)致新的修理混凝土結(jié)構(gòu)方面的鋼筋腐蝕。因此，在保護(hù)方法上有所體現(xiàn)。</p><p>　　為修理結(jié)構(gòu)中鋼筋的附加保護(hù)，而批評已存在的方法和材料，或者徹底討論一個(gè)保護(hù)系統(tǒng)的優(yōu)

19、點(diǎn)或者過失不是本論文的意圖。作者沒有表達(dá)明確意見，或者至少對修理結(jié)構(gòu)的保護(hù)鋼筋的正確或錯(cuò)誤方法表示合理客觀的意見。非常抱歉的是，并不如此。問題太復(fù)雜，因?yàn)楝F(xiàn)有的知識不能夠提供一劑萬能方法來解決現(xiàn)有的問題。</p><p>　　由于鋼筋鋼過早的腐蝕而產(chǎn)生修理失敗的結(jié)果和可能性，不一定是一種單個(gè)的過分簡化的解決辦法，這可能適合于新近建造的結(jié)構(gòu)。在修理領(lǐng)域內(nèi)，我們的成功可能取決于我們解決爭論的能力。把感覺和廢話區(qū)別開。

20、無論我們做什么，無用的言論總是很多。在這個(gè)領(lǐng)域，由于缺乏適當(dāng)?shù)慕逃壳霸S多專業(yè)詞語被錯(cuò)誤定義。不適當(dāng)?shù)慕逃脱芯吭谌魏晤I(lǐng)域都將要花大力氣來改正誤解。</p><p>　　作者意識到當(dāng)一些論點(diǎn)成為爭論的關(guān)鍵時(shí)，那些論點(diǎn)將很難讓人達(dá)成共識。而且這種情況，遠(yuǎn)遠(yuǎn)多過一根頭發(fā)。或許，我們將從誤解中來剝離真正的理解。</p><p><b>　　2.腐蝕問題：</b></

21、p><p>　?。?）用于被修理混凝土結(jié)構(gòu)嵌入鋼筋的腐蝕和它的保護(hù)是一個(gè)非常復(fù)雜的現(xiàn)象。 很多修理失敗可能歸因于缺乏對自然和電化學(xué)活動(dòng)在修理系統(tǒng)內(nèi)結(jié)果的完整理解。因此，預(yù)言一個(gè)保護(hù)系統(tǒng)的性能和一棟修理結(jié)構(gòu)的使用年限是不太準(zhǔn)確的。</p><p>　　(2) 在聲稱多種特性的市場上有許多腐蝕保護(hù)處理方法。他們保護(hù)鋼筋防止腐蝕的行為沒有處理好，并且沒有可靠的標(biāo)準(zhǔn)測驗(yàn)方法評價(jià)他們所表現(xiàn)的性能。 適量

22、的研究要求為不同系統(tǒng)的評估作準(zhǔn)備。需要知道結(jié)構(gòu)負(fù)擔(dān)這種保護(hù)有多久，修理結(jié)構(gòu)的保護(hù)就有多好。為了給技術(shù)人員建立自信，科學(xué)家應(yīng)該為預(yù)知措施和預(yù)測的壽命提供可信的基點(diǎn)。</p><p>　　(3) 過度期望或者修理系統(tǒng)的糟糕表現(xiàn)以及暴露狀況，特別在實(shí)驗(yàn)室中的內(nèi)部測試，經(jīng)常產(chǎn)生使人誤解的結(jié)果。如果過去評價(jià)這些保護(hù)系統(tǒng)的測驗(yàn)方法，既不反映出修理結(jié)構(gòu)中腐蝕的機(jī)制，也不刺激在一個(gè)真正修理的結(jié)構(gòu)里而導(dǎo)致鋼筋腐蝕的物理化學(xué)效應(yīng)。我

23、們怎能期望花費(fèi)在修理的鋼筋附加保護(hù)上錢沒被浪費(fèi)？目前使用過的一些測驗(yàn)方法以后的研究范圍也相當(dāng)狹窄。 </p><p>　　(4) 各種不同的保護(hù)方法的調(diào)查員都在說他們方法的效力總是比在高質(zhì)量混凝土中還好?？梢詳喽ǜ哔|(zhì)量新混凝土和高質(zhì)量的修理是埋入鋼筋防止腐蝕的最好保護(hù)系統(tǒng) -- 這是混凝土技術(shù)的基礎(chǔ)。 保護(hù)措施可以另外采取，但不是做為使用基礎(chǔ)的正確代用品。 </p><p>　　(5) 這

24、篇文章的中心主題考慮的不是作者在幾個(gè)問題上意見的正確或者錯(cuò)誤； 那是不相關(guān)的。它的意思是提出的問題不是無法解釋的秘密，只是我們?nèi)匀辉谔剿骼锏囊粋€(gè)證明，簡稱研究階段。畢竟本杰明·富蘭克林說過，"做永遠(yuǎn)比說好"！</p><p><b>　　Abstract</b></p><p>　　In recent times in many part

25、s of the world, reinforcement corrosion has become the main factor in early, premature deterioration, and sometimes failure, of concrete structures. One of the major factors contributing to this deterioration process is

26、the environmental and climatic conditions to which a concrete structure is exposed. When the severity of environment is compounded with poor quality concrete and/or defective design and construction practices, the proces

27、s of deterioration becomes inter</p><p>　　2003 Elsevier Ltd. All rights reserved.</p><p>　　Keywords: Alkalinity; Corrosion protection; Durability; Inhibitors; Reinforcement</p>

28、<p>　　1. Introduction</p><p>　　It is an unfortunate fact that very large amounts of existing concrete structures worldwide are in a state of eterioration/distress. At the same time, it must also be reco

29、gnized that many repaired concrete structures are severely deteriorated only a few years after being repaired. The performance of repaired concrete structures remains a matter of utmost concern to all those involved with

30、 their design, construction, maintenance and use. Few problems aggravate the public and lead to their dissati</p><p>　　The concrete repair industry is thus facing a major challenge: How to halt the decay of

31、the world’s physical infrastructure. It is therefore important that we critically examine the issue of corrosion and corrosion protection in today’s concrete repair and explore how it can be improved in the near future,

32、i.e.: how to make today’s repairs durable for tomorrow. A basic understanding of the processes leading to premature corrosion in repaired structures still eludes the concrete repair community.</p><p>　　This

33、paper offers some random thoughts in the area of reinforcement corrosion and protection in concrete repair. It encompasses the elucidation of the basic processes of corrosion of steel in repair, electrochemical incompati

34、bility, and how these processes may lead to eventual failure of the composite repair system. The paper is also about how we can, or cannot, successfully address these problems with the aim of prolonging lifetime of exist

35、ing concrete structures. After all, we must pause perio</p><p>　　It is not possible here to provide a critical review of numerous aspects of corrosion and corrosion protection, the problems are too extensive

36、 and various mechanisms too complicated for a critical discussion in a single paper. General aspects of steel corrosion in concrete and its protection have been treated by a number of authors and will not be addressed he

37、re.</p><p>　　Research has substantially improved our knowledge of cementitious materials, the fundamentals of concrete deterioration from carbonation-induced corrosion, chloride-induced corrosion, sulphate a

38、ttack, alkali–aggregate reaction, frost, etc. However, in view of the serious and insidious nature of the corrosion of steel in concrete repair and repair failures, it is surprising that progress in the repair industry h

39、as been so slow, which is probably attributable to some combination of the following:</p><p>　　the exterior and interior environments and their interaction.</p><p>　　problems does not exist. The

40、 mechanism of passivation and corrosion of steel in a complex repair environment is poorly understood. The whole area concerning “additional protection” of reinforcement in repair is currently highly speculative.</p&g

41、t;<p>　　is an extremely complex phenomenon involving environmental, metallurgical, interfacial, and continuum considerations. Most of the research in this area is being done by the civil engineering departments of

42、 universities where few workers have adequate knowledge of the subject.</p><p>　　in support of research leading to a resolution to problems. Real progress cannot be made on the basis of "graduate studen

43、ts working for limited periods". It is necessary to initiate programs which include a balanced practical approach and are adequately funded.</p><p>　　by using "high performance" materials, cor

44、rosion inhibitors, protective coatings, etc., or belt and suspender systems. This caused many workers in the field to ignore the basics in the technology of concrete and other cement-based materials.</p><p>

45、　　ficant knowledge to design durable repairs already exists in a relatively “quite refined state”, as stated by Mather [1]. But the manner in which this knowledge is used is primitive.</p><p>　　Several resea

46、rch studies in the repair field have been concerned with the improvement of properties of repair materials and their dimensional behaviour relative to the existing substrate. But these activities will lead to improvement

47、s in repair durability only if the issues of electrochemical compatibility are also addressed. Removal of deteriorated concrete and its replacement with a repair material, even the best one, may result in accelerated reb

48、ar corrosion due to macrocell formation.</p><p>　　The subject of this paper is also devoted to several confusing issues and attempts to establish the facts concerning the protection of reinforcement from pre

49、mature corrosion in concrete repair, particularly that offered by corrosion inhibitors.</p><p>　　How can we expect repaired concrete structures to be durable if the testing methods, design and specification

50、of corrosion protection methods, are relying on an inadequate assumption that electrochemistry in a repair system is similar to that occurring in "new construction?" There are significant differences between ne

51、w construction and repair jobs; there are often different factors leading to corrosion of reinforcement in new an repaired concrete structures and, therefore, in the methods of pro</p><p>　　It is not the int

52、ent of this paper to criticize existing methods and materials for additional protection of reinforcement in repairs, or to discuss in depth the merits or demerits of one protection system against another. The author can

53、offer no panacea, or at least express a reasonably objective view of the right and wrong way to protect reinforcement in repaired structures. Much to our regret, this is not so. The problem is too complex because the exi

54、sting knowledge is not sufficient to offer </p><p>　　The consequence and probability of repair failure due to the premature corrosion of the reinforcing steel is not necessarily a single simplistic solution

55、as may be appropriate for newly constructed structures. Our success in the repair field may depend on our ability to resolve the controversies, to differentiate sense from nonsense. The nonsense will be abundant, no matt

56、er what we do: this field, due to the lack of proper education, is presently well positioned to import a lot of misconceptions</p><p>　　The author realizes that some statements will not be shared by many sin

57、ce it hits at the crux of the controversy. But in this case, much more than a hair, perhaps, divides concepts from misconcepts.</p><p>　　2. A glimpse of corrosion problem</p><p>　　According to p

58、ublished data, steel reinforcement in concrete and in concrete-like materials is, in general, well protected from corrosion by the alkaline nature of the cementitious matrix surrounding it. In general, this is true, it i

59、s protected, and it is not supposed to corrode. But such concrete "in general" may only exist as "labcrete", in a small specimen. In the real world, reinforcing and prestressing steels are subject to

60、corrosion due to carbonation and chloride ion attack.</p><p>　　Steel reinforcement in concrete does not corrode because the surface of the steel in the alkaline environment is passivated; steel in concrete c

61、orrodes when its surface is depassivated during the manufacturing of the structure, or becomes active during service. Corrosion is the electrochemical reaction, and the important factor affecting a corrosion cell is the

62、difference in potentials of the metal. The driving force for current and corrosion is the potential development. Since the structure of </p><p>　　Concrete is a permeable material, where aggressive agents dif

63、fuse (micropermeability) through it and reach the reinforcing steel, causing its depassivation and corrosion, when water and oxygen are available. Corrosion by this mode however, is a relatively lengthy process. Concrete

64、 is a brittle material and always contains microcracks. When these microcracks combine in a network with macrocracks, the prevailing transport mechanism is not diffusion, it is the permeation of water and aggressive age&

65、lt;/p><p>　　High permeability of concrete and other cementbased materials affected by cracking is truly responsible for the lack of durability. For corrosion to occur, it is necessary that both the passivating

66、.lm on the steel is destroyed and that there exists a differential electrochemical potential within the steel–concrete system.The natural protection of steel by the high alkalinity of cement matrix is disturbed due to th

67、e following reasons:</p><p>　　chemical reaction between the products of hydration of cement and carbon dioxide which diffuses from the atmosphere (carbonation). Carbonation by diffusion is a very lengthy pro

68、cess: approximately 1 mm of concrete cover carbonates in a year. Cracks in the concrete, on the other hand, allow carbon dioxide easy permeation through the concrete cover, and carbonation occurs rapidly.</p><

69、p>　　level. Chloride ions may penetrate into the concrete due to one of three processes: diffusion due to a concentration gradient, absorption from salt solutions form, and/or by flow of the solution through the cracks

70、.</p><p>　　The differential electrochemical potential may develop due to the dissimilarities in the chemical environment of steel, such as the result of nonuniformed carbonation, the variation in the rate of

71、 penetration of chlorides, moisture, oxygen, etc. Reinforcing steel in the variety of a crack starts to corrode from a localized depassivation of steel because of the weakened steel-cement-matrix contact and disturbed st

72、eel passivating film. Steel depassivates from reduced alkalinity at the surface of t</p><p>　　Acid gasses and aggressive ions penetrate the cracked material much easier than they do in crack-free concrete. T

73、he active coefficient of carbon dioxide diffusion (penetration) in a concrete crack 0.20 mm (0.008 in.) wide is about three orders of magnitude higher than in average quality crack-free concrete. The same holds true for

74、the transport of aggressive ions, the rate of substance transfer by capillary suction is even greater. According to previous data reinforcement in a crack wider than 0</p><p>　　which oxygen reaches the catho

75、de. The width and the direction of cracks are not of critical importance, but the amount of cracks per unit of area is critical.</p><p>　　Repairs are more prone to cracking and, therefore, to corrosion than

76、newly constructed concrete structures. When freshly placed and hardened repair material is exposed to ambient temperature and humidity, it experiences drying shrinkage strain. The type and magnitude of this strain will d

77、epend on the characteristics of the repair material, temperature and the humidity of the environment, the geometry of the repair, the degree of the restraint, and the temperatures of the repair material and subs</p>

78、;<p>　　Transport of substances through and in the repair system is a very complex process, consisting of a combination of liquid flow through macro and microcrack systems, capillary transport, diffusion, and osmot

79、ic effects. The exact contribution of each process needs to be quantified in each particular situation. The effects of such variables as location of the repair in the structure, chemical environment in the composite repa

80、ir system, amount and distribution of cracks in both phases, temperature, </p><p>　　It appears that adequate attention to the specifics of concrete repair––its significant differences with new construction––

81、is not paid by those who commission and perform repairs. The three primary issues related to premature corrosion in repaired concrete structures, namely cracking as a result of drying-shrinkage, electrochemical incompati

82、bility, and changes in interior environment caused by repair requires due consideration. Therefore, a brief review of the principles governing the failure of</p><p>　　When an existing concrete structure, suf

83、fering from corrosion of embedded reinforcement and concrete deterioration, is being repaired, some of the chloride contaminated concrete may be left in place. In this case, there is always a risk that corrosion activity

84、 may continue or even accelerate, because the repair phase has a different moisture, oxygen and chloride content than the surrounding concrete, and strong corrosion cells may be established resulting in spalling of the r

85、epair itself or, mor</p><p>　　It is difficult to predict the effect of a repair on electrochemical activity in a repaired structure because it is a function of the change in potentials, the nature of the rep

86、air materials, and the exterior and interior environments. If the steel in the repair area is only partially exposed with a bar that is embedded halfway in existing, chloride-contaminated concrete and halfway in new repa

87、ir material, strong corrosion cells may develop. The half of the bar in the existing concrete will beco</p><p>　　The durability criteria for concrete repairs differs from that of newly constructed concrete s

88、tructures [4].</p><p>　　The factors that relate to such durability criteria are not only normal physical and chemical attacks from the exterior environment, but the attack from the interior environment and t

89、he changes in the interior environment created by the application of the repair material.</p><p>　　It is never advisable to design any structure without first having a very clear idea of what environment it

90、is going to be exposed to, and how it is going to behave in this environment. Unfortunately, repair projects are often not designed this way. Very little consideration is given to the interior environment in the repair s

91、ystem and, therefore, little is known about how the repair will behave in this environment. In repair systems, the interior is constantly changing due to the existence of t</p><p>　　With a complex composite

92、system such as a concrete repair, aggressive exterior and interior environments, and their interaction, become a major factor in initiating a progressively cumulative damage attack. Progression of reinforcement corrosion

93、 and concrete deterioration becomes an overall synergistic process, a complex combination of a variety of individual mechanisms, the exact role, effect and contribution of each is not clearly understood. Variability in a

94、lmost everything is typical for rep</p><p>　　Conclusions</p><p>　　(1) Corrosion of embedded reinforcement and its protection in repaired concrete structures is a very complex phenomenon. Many re

95、pair failures can be attributed to the lack of complete understanding of the nature and consequences of electrochemical activities in a repair system, and therefore, to an inability to accurately predict the performance

96、of a protective system and service life of a repaired structure.</p><p>　　(2) There are a large number of corrosion protection treatments on the market that claim a variety of properties. Their behavior in p

97、rotection against corrosion of reinforcement is not well established, and there are no reliable standard test methods to assess their likely performance. Adequate research is required to provide for evaluation of differe

98、nt systems. One needs to know how good the protected repair structure is, and how long it will afford that protection. In order to give confidence </p><p>　　(3) Overmagnification or poor reproduction of repa

99、ir systems and exposure conditions, especially interior ones, in laboratory tests, often produce misleading results. How can one expect that the money spent on additional protection of reinforcement in repairs is not was

100、ted, if test methods used to evaluate these protective systems neither reflect the mechanisms of corrosion in repaired structures, nor stimulate the physicochemical effects that lead to corrosion of steel in a real repai