土木工程畢業(yè)論文外文翻譯--建筑施工混凝土裂縫的預(yù)防與處理

1、<p>　　《CANADIAN JOURNAL OF CIVIL ENGINEERING》</p><p>　　Abstract：The crack problem of concrete is a widespread existence but again difficult in solve of engineering actual problem, this text carried on a

2、 study analysis to a little bit familiar crack problem in the concrete engineering, and aim at concrete the circumstance put forward some prevention, processing measure. </p><p>　　Keyword: Concrete crack pre

3、vention processing</p><p><b>　　Foreword</b></p><p>　　Concrete's ising 1 kind is anticipate by the freestone bone, cement, water and other mixture but formation of the in addition

4、 material of quality brittleness not and all material.Because the concrete construction transform with oneself, control etc. a series problem, harden model of in the concrete existence numerous tiny hole, spirit cave and

5、 tiny crack, is exactly because these beginning start blemish of existence just make the concrete present one some not and all the characteristic of qualit</p><p>　　Concrete building and Gou piece usually al

6、l take sewer to make of, because of crack of existence and development usually make inner part of reinforcing bar etc. material creation decay, lower reinforced concrete material of loading ability, durable and anti- She

7、n ability, influence building of external appearance, service life, severity will threat arrive people's life and property safety.A lot of all of crash of engineerings is because of the unsteady development of the cr

8、ack with the result th</p><p>　　Concrete crack creation of the reason be a lot of and have already transformed to cause of crack:Such as temperature variety, constringency, inflation, the asymmetry sink to s

9、ink etc. reason cause of crack;Have outside carry the crack that the function cause;Protected environment not appropriate the crack etc. caused with chemical effect.Want differentiation to treat in the actual engineering

10、, work°out a problem according to the actual circumstance.</p><p>　　In the concrete engineering the familiar crack and the prevention</p><p>　　1.Stem Suo crack and prevention</p><

11、;p>　　Stem the Suo crack much appear after the concrete protect be over of a period of time or concrete sprinkle to build to complete behind of around a week.In the cement syrup humidity of evaporate would creation ste

12、m Suo, and this kind of constringency is can't negative.Stem Suo crack of the creation be main is because of concrete inside outside humidity evaporate degree dissimilarity but cause to transform dissimilarity of res

13、ult:The concrete is subjected to exterior condition of influence, surfac</p><p>　　Main prevention measure:While being to choose to use the constringency quantity smaller cement, general low hot water mire an

14、d powder ash from stove cement in the adoption, lower the dosage of cement.Two is a concrete of stem the Suo be subjected to water ash ratio of influence more big, water ash ratio more big, stem Suo more big, so in the c

15、oncrete match the ratio the design should as far as possible control good water ash ratio of choose to use, the Chan add in the meantime accommodation of r</p><p>　　2.The Su constringency crack and preventio

16、n</p><p>　　Su constringency is the concrete is before condense, surface because of lose water quicker but creation of constringency.The Su constringency crack is general at dry heat or strong wind the weathe

17、r appear, crack's much presenting in the center breadth, both ends be in the centerthin and the length be different, with each other not coherent appearance.Shorter crack general long 20-30 cm, the longer crack can r

18、each to a 2-3 m, breadth 1-5 mm.It creation of main reason is:The concrete is eventually</p><p>　　Main prevention measure:One is choose to use stem the Suo value smaller higher Huo sour salt of the earlier p

19、eriod strength or common the Huo sour brine mire.Two is strict the control water ash ratio, the Chan add to efficiently reduce water to increment the collapse of concrete fall a degree and with easy, decrease cement and

20、water of dosage.Three is to sprinkle before building concrete, water basic level and template even to soak through.Four is in time to overlay the perhaps damp grass mat of</p><p>　　3.Sink to sink crack and p

21、revention</p><p>　　The creation which sink to sink crack is because of the structure foundation soil quality not and evenly, loose soft or return to fill soil dishonest or soak in water but result in the asy

22、mmetry sink to decline with the result that;Perhaps because of template just degree shortage, the template propped up to once be apart from big or prop up bottom loose move etc. to cause, especially at winter, the templa

23、te prop up at jelly soil up, jelly the soil turn jelly empress creation asymmetry to sink to</p><p>　　Main prevention measure:One is rightness loose soft soil, return to fill soil foundation a construction a

24、t the upper part structure front should carry on necessity of Hang solid with reinforce.Two is the strength that assurance template is enough and just degree, and prop up firm, and make the foundation be subjected to din

25、t even.Three is keep concrete from sprinkle infusing the foundation in the process is soak by water.Four is time that template tore down to can't be too early, and want to not</p><p>　　4.Temperature crac

26、k and prevention</p><p>　　Temperature crack much the occurrence is in big surface or difference in temperature variety of the physical volume concrete compare the earth area of the concrete structure.Concret

27、e after sprinkling to build, in the hardening the process, cement water turn a creation a great deal of of water turn hot, .(be the cement dosage is in the 350-550 kg/m 3, each sign square the rice concrete will release

28、a calories of 17500-27500 kJ and make concrete internal thus the temperature rise to reach to 70 ℃ </p><p>　　The alignment of the temperature crack usually none settle regulation, big area structure the crac

29、k often maneuver interleave;The size bigger structure of the beam plank length, the crack run parallel with short side more;Thorough with pierce through sex of temperature crack general and short side direction paralleli

30、sm or close parallelism, crack along long side cent the segment appear, in the center more airtight.Crack width the size be different, be subjected to temperature variety influence m</p><p>　　Main prevention

31、 measure:One is as far as possible choose to use low hot or medium hot water mire, like mineral residue cement, powder ash from stove cement...etc..Two is a decrease cement dosage, cement dosage as far as possible the co

32、ntrol is in the 450 kg/m 3 following.Three is to lower water ash ratio, water ash of the general concrete ratio control below 0.6.Four is improvement the bone anticipate class to go together with, the Chan add powder ash

33、 from stove or efficiently reduce water etc. </p><p>　　5.Crack and prevention that the chemical reaction cause</p><p>　　Alkali bone's anticipating the crack that reaction crack and reinforci

34、ng bar rust eclipse cause is the most familiar in the reinforced concrete structure of because of chemical reaction but cause of crack.</p><p>　　The concrete blend a future reunion creation some alkalescence

35、 ion, these ion with some activity the bone anticipate creation chemical reaction and absorb surroundings environment in of water but the physical volume enlarge, make concrete crisp loose, inflation open crack.In this k

36、ind of crack general emergence concrete structure usage period, once appear very difficult remediable, so should at under construction adopt valid the measure carry on prevention.Main of prevention measure:While being &l

37、t;/p><p>　　Because the concrete sprinkle to build, flap Dao bad perhaps is a reinforcing bar protection layer thinner, the harmful material get into concrete to make reinforcing bar creation rust eclipse, the r

38、einforcing bar physical volume of the rust eclipse inflation, cause concrete bulge crack, the crack of this kind type much is a crack lengthways, follow the position of reinforcing bar appear.Usually of prevent measure f

39、rom have:One is assurance reinforcing bar protection the thickness of the layer.T</p><p>　　Crack processing</p><p>　　The emergence of the crack not only would influence structure of whole with j

40、ust degree, return will cause the rust eclipse of reinforcing bar, acceleration concrete of carbonization, lower durable and anti- of concrete tired, anti- Shen ability.Therefore according to the property of crack and co

41、ncrete circumstance we want differentiation to treat, in time processing, with assurance building of safety usage.</p><p>　　The repair measure of the concrete crack is main to have the following some method:

42、Surface repair method, infuse syrup, the Qian sew method, the structure reinforce a method, concrete displacement method, electricity chemistry protection method and imitate to living from heal method.</p><p&g

43、t;　　Surface repair the method be a kind of simple, familiar of repair method, it main be applicable to stability and to structure loading the ability don't have the surface crack of influence and deep enter crack of

44、processing.The processing measure that is usually is a surface in crack daubery cement syrup, the wreath oxygen gum mire or at concrete surface Tu2 Shua paint, asphalt etc. antisepsis material, at protection of in the me

45、antime for keeping concrete from continue under the influence of var</p><p>　　1, infuse syrup, the Qian sew method</p><p>　　Infuse a syrup method main the concrete crack been applicable to have

46、influence or have already defend Shen request to the structure whole of repair, it is make use of pressure equipments gum knot the material press into the crack of concrete, gum knot the material harden behind and concre

47、te formation one be whole, thus reinforce of purpose.The in common use gum knot material has the cement the syrup, epoxy, A Ji C Xi sour ester and gather ammonia ester to equalize to learn material.</p><p>　

48、　The Qian sew a method is that the crack be a kind of most in common use method in, it usually is follow the crack dig slot, the Qian fill Su in the slot or rigid water material with attain closing crack of purpose.The i

49、n common use Su material has PVC gum mire, plastics ointment, the D Ji rubber etc.;In common use rigid water material is the polymer cement sand syrup.</p><p>　　2, the structure reinforce a method</p>

50、<p>　　When the crack influence arrive concrete structure of function, will consideration adopt to reinforce a method to carry on processing to the concrete structure.The structure reinforce medium in common use mai

51、n have the following a few method:The piece of enlargement concrete structure in every aspect accumulate, outside the Cape department of the Gou piece pack type steel, adoption prepare should the dint method reinforce, g

52、lue to stick steel plate to reinforce, increase to establish fulcrum to </p><p>　　3, concrete displacement method</p><p>　　Concrete displacement method is processing severity damage concrete of

53、a kind of valid method, this method be first will damage of the concrete pick and get rid of, then again displacement go into new of concrete or other material.The in common use displacement material have:Common concrete

54、 or the cement sand syrup, polymer or change sex polymer concrete or sand syrup.</p><p>　　4, the electricity chemistry protection method</p><p>　　The electricity chemistry antisepsis is to make

55、use of infliction electric field in lie the quality of electricity chemical effect, change concrete or reinforced concrete the environment appearance of the place, the bluntness turn reinforcing bar to attain the purpose

56、 of antisepsis.Cathode protection method, chlorine salt's withdrawing a method, alkalescence to recover a method is a chemistry protection method in three kinds of in common use but valid method.The advantage of this

57、 kind of method </p><p>　　5, imitate to living from legal more</p><p>　　Imitate to living from heal the method be a kind of new crack treatment, its mimicry living creature organization secrete

58、a certain material towards suffering wound part auto, but make the wound part heal of function, join some and special composition(such as contain to glue knot of the liquid Xin fiber or capsule) in the concrete of the tr

59、adition the composition, at concrete inner part formation the intelligence type imitate to living from heal nerve network system, be the concrete appear crack</p><p>　　Conclusion</p><p>　　The cr

60、ack is widespread in the concrete structure existence of a kind of phenomenon, it of emergence not only will lower the anti- Shen of building ability, influence building of usage function, and will cause the rust eclipse

61、 of reinforcing bar, the carbonization of concrete, lower the durable of material, influence building of loading ability, so want to carry on to the concrete crack earnest research, differentiation treat, adoption reason

62、able of the method carry on processing, and at under c</p><p>　　Building construction concrete crack of</p><p>　　prevention and processing</p><p>　　建筑施工混凝土裂縫的預(yù)防與處理</p><p&

63、gt;　　摘要：混凝土的裂縫問題是一個(gè)普遍存在而又難于解決的工程實(shí)際問題，本文對(duì)混凝土工程中常見的一些裂縫問題進(jìn)行了探討分析，并針對(duì)具體情況提出了一些預(yù)防、處理措施。</p><p>　　關(guān)鍵詞：混凝土 裂縫 預(yù)防 處理</p><p><b>　　前言</b></p><p>　　混凝土是一種由砂石骨料、水泥、水及其他外加材料混合而形成的非均

64、質(zhì)脆性材料。由于混凝土施工和本身變形、約束等一系列問題，硬化成型的混凝土中存在著眾多的微孔隙、氣穴和微裂縫，正是由于這些初始缺陷的存在才使混凝土呈現(xiàn)出一些非均質(zhì)的特性。微裂縫通常是一種無害裂縫，對(duì)混凝土的承重、防滲及其他一些使用功能不產(chǎn)生危害。但是在混凝土受到荷載、溫差等作用之后，微裂縫就會(huì)不斷的擴(kuò)展和連通，最終形成我們?nèi)庋劭梢姷暮暧^裂縫，也就是混凝土工程中常說的裂縫。</p><p>　　混凝土建筑和構(gòu)件通常都

65、是帶縫工作的，由于裂縫的存在和發(fā)展通常會(huì)使內(nèi)部的鋼筋等材料產(chǎn)生腐蝕，降低鋼筋混凝土材料的承載能力、耐久性及抗?jié)B能力，影響建筑物的外觀、使用壽命，嚴(yán)重者將會(huì)威脅到人們的生命和財(cái)產(chǎn)安全。很多工程的失事都是由于裂縫的不穩(wěn)定發(fā)展所致。近代科學(xué)研究和大量的混凝土工程實(shí)踐證明，在混凝土工程中裂縫問題是不可避免的，在一定的范圍內(nèi)也是可以接受的，只是要采取有效的措施將其危害程度控制在一定的范圍之內(nèi)。鋼筋混凝土規(guī)范也明確規(guī)定：有些結(jié)構(gòu)在所處的不同條件下，

66、允許存在一定寬度的裂縫。但在施工中應(yīng)盡量采取有效措施控制裂縫產(chǎn)生，使結(jié)構(gòu)盡可能不出現(xiàn)裂縫或盡量減少裂縫的數(shù)量和寬度，尤其要盡量避免有害裂縫的出現(xiàn)，從而確保工程質(zhì)量。</p><p>　　混凝土裂縫產(chǎn)生的原因很多，有變形引起的裂縫：如溫度變化、收縮、膨脹、不均勻沉陷等原因引起的裂縫；有外載作用引起的裂縫；有養(yǎng)護(hù)環(huán)境不當(dāng)和化學(xué)作用引起的裂縫等等。在實(shí)際工程中要區(qū)別對(duì)待，根據(jù)實(shí)際情況解決問題。</p>&

67、lt;p>　　混凝土工程中常見裂縫及預(yù)防:</p><p><b>　　1.干縮裂縫及預(yù)防</b></p><p>　　干縮裂縫多出現(xiàn)在混凝土養(yǎng)護(hù)結(jié)束后的一段時(shí)間或是混凝土澆筑完畢后的一周左右。水泥漿中水分的蒸發(fā)會(huì)產(chǎn)生干縮，且這種收縮是不可逆的。干縮裂縫的產(chǎn)生主要是由于混凝土內(nèi)外水分蒸發(fā)程度不同而導(dǎo)致變形不同的結(jié)果：混凝土受外部條件的影響，表面水分損失過快，變形

68、較大，內(nèi)部濕度變化較小變形較小，較大的表面干縮變形受到混凝土內(nèi)部約束，產(chǎn)生較大拉應(yīng)力而產(chǎn)生裂縫。相對(duì)濕度越低，水泥漿體干縮越大，干縮裂縫越易產(chǎn)生。干縮裂縫多為表面性的平行線狀或網(wǎng)狀淺細(xì)裂縫，寬度多在0.05-0.2mm之間，大體積混凝土中平面部位多見，較薄的梁板中多沿其短向分布。干縮裂縫通常會(huì)影響混凝土的抗?jié)B性，引起鋼筋的銹蝕影響混凝土的耐久性，在水壓力的作用下會(huì)產(chǎn)生水力劈裂影響混凝土的承載力等等。混凝土干縮主要和混凝土的水灰比、水泥的

69、成分、水泥的用量、集料的性質(zhì)和用量、外加劑的用量等有關(guān)。</p><p>　　主要預(yù)防措施：一是選用收縮量較小的水泥，一般采用中低熱水泥和粉煤灰水泥，降低水泥的用量。二是混凝土的干縮受水灰比的影響較大，水灰比越大，干縮越大，因此在混凝土配合比設(shè)計(jì)中應(yīng)盡量控制好水灰比的選用，同時(shí)摻加合適的減水劑。三是嚴(yán)格控制混凝土攪拌和施工中的配合比，混凝土的用水量絕對(duì)不能大于配合比設(shè)計(jì)所給定的用水量。四是加強(qiáng)混凝土的早期養(yǎng)護(hù)，并

70、適當(dāng)延長混凝土的養(yǎng)護(hù)時(shí)間。冬季施工時(shí)要適當(dāng)延長混凝土保溫覆蓋時(shí)間，并涂刷養(yǎng)護(hù)劑養(yǎng)護(hù)。五是在混凝土結(jié)構(gòu)中設(shè)置合適的收縮縫。</p><p>　　2.塑性收縮裂縫及預(yù)防</p><p>　　塑性收縮是指混凝土在凝結(jié)之前，表面因失水較快而產(chǎn)生的收縮。塑性收縮裂縫一般在干熱或大風(fēng)天氣出現(xiàn)，裂縫多呈中間寬、兩端細(xì)且長短不一，互不連貫狀態(tài)。較短的裂縫一般長20-30cm，較長的裂縫可達(dá)2-3m，寬1-

71、5mm.其產(chǎn)生的主要原因?yàn)椋夯炷猎诮K凝前幾乎沒有強(qiáng)度或強(qiáng)度很小，或者混凝土剛剛終凝而強(qiáng)度很小時(shí)，受高溫或較大風(fēng)力的影響，混凝土表面失水過快，造成毛細(xì)管中產(chǎn)生較大的負(fù)壓而使混凝土體積急劇收縮，而此時(shí)混凝土的強(qiáng)度又無法抵抗其本身收縮，因此產(chǎn)生龜裂。影響混凝土塑性收縮開裂的主要因素有水灰比、混凝土的凝結(jié)時(shí)間、環(huán)境溫度、風(fēng)速、相對(duì)濕度等等。</p><p>　　主要預(yù)防措施：一是選用干縮值較小早期強(qiáng)度較高的硅酸鹽或普通

72、硅酸鹽水泥。二是嚴(yán)格控制水灰比，摻加高效減水劑來增加混凝土的坍落度和和易性，減少水泥及水的用量。三是澆筑混凝土之前，將基層和模板澆水均勻濕透。四是及時(shí)覆蓋塑料薄膜或者潮濕的草墊、麻片等，保持混凝土終凝前表面濕潤，或者在混凝土表面噴灑養(yǎng)護(hù)劑等進(jìn)行養(yǎng)護(hù)。五是在高溫和大風(fēng)天氣要設(shè)置遮陽和擋風(fēng)設(shè)施，及時(shí)養(yǎng)護(hù)。</p><p><b>　　3.沉陷裂縫及預(yù)防</b></p><p&

73、gt;　　沉陷裂縫的產(chǎn)生是由于結(jié)構(gòu)地基土質(zhì)不勻、松軟或回填土不實(shí)或浸水而造成不均勻沉降所致；或者因?yàn)槟０鍎偠炔蛔?，模板支撐間距過大或支撐底部松動(dòng)等導(dǎo)致，特別是在冬季，模板支撐在凍土上，凍土化凍后產(chǎn)生不均勻沉降，致使混凝土結(jié)構(gòu)產(chǎn)生裂縫。此類裂縫多為深進(jìn)或貫穿性裂縫，其走向與沉陷情況有關(guān)，一般沿與地面垂直或呈30°-45°角方向發(fā)展，較大的沉陷裂縫，往往有一定的錯(cuò)位，裂縫寬度往往與沉降量成正比關(guān)系。裂縫寬度受溫度變化的影

74、響較小。地基變形穩(wěn)定之后，沉陷裂縫也基本趨于穩(wěn)定。</p><p>　　主要預(yù)防措施：一是對(duì)松軟土、回填土地基在上部結(jié)構(gòu)施工前應(yīng)進(jìn)行必要的夯實(shí)和加固。二是保證模板有足夠的強(qiáng)度和剛度，且支撐牢固，并使地基受力均勻。三是防止混凝土澆灌過程中地基被水浸泡。四是模板拆除的時(shí)間不能太早，且要注意拆模的先后次序。五是在凍土上搭設(shè)模板時(shí)要注意采取一定的預(yù)防措施。</p><p><b>　　4

75、.溫度裂縫及預(yù)防</b></p><p>　　溫度裂縫多發(fā)生在大體積混凝土表面或溫差變化較大地區(qū)的混凝土結(jié)構(gòu)中。混凝土澆筑后，在硬化過程中，水泥水化產(chǎn)生大量的水化熱，（當(dāng)水泥用量在350-550 kg/m3，每立方米混凝土將釋放出17500-27500kJ的熱量，從而使混凝土內(nèi)部溫度升達(dá)70℃左右甚至更高）。由于混凝土的體積較大，大量的水化熱聚積在混凝土內(nèi)部而不易散發(fā)，導(dǎo)致內(nèi)部溫度急劇上升，而混凝土表

76、面散熱較快，這樣就形成內(nèi)外的較大溫差，較大的溫差造成內(nèi)部與外部熱脹冷縮的程度不同，使混凝土表面產(chǎn)生一定的拉應(yīng)力。當(dāng)拉應(yīng)力超過混凝土的抗拉強(qiáng)度極限時(shí)，混凝土表面就會(huì)產(chǎn)生裂縫，這種裂縫多發(fā)生在混凝土施工中后期。在混凝土的施工中當(dāng)溫差變化較大，或者是混凝土受到寒潮的襲擊等，會(huì)導(dǎo)致混凝土表面溫度急劇下降，而產(chǎn)生收縮，表面收縮的混凝土受內(nèi)部混凝土的約束，將產(chǎn)生很大的拉應(yīng)力而產(chǎn)生裂縫，這種裂縫通常只在混凝土表面較淺的范圍內(nèi)產(chǎn)生。</p>

77、<p>　　溫度裂縫的走向通常無一定規(guī)律，大面積結(jié)構(gòu)裂縫?？v橫交錯(cuò)；梁板類長度尺寸較大的結(jié)構(gòu)，裂縫多平行于短邊；深入和貫穿性的溫度裂縫一般與短邊方向平行或接近平行，裂縫沿著長邊分段出現(xiàn)，中間較密。裂縫寬度大小不一，受溫度變化影響較為明顯，冬季較寬，夏季較窄。高溫膨脹引起的混凝土溫度裂縫是通常中間粗兩端細(xì)，而冷縮裂縫的粗細(xì)變化不太明顯。此種裂縫的出現(xiàn)會(huì)引起鋼筋的銹蝕，混凝土的碳化，降低混凝土的抗凍融、抗疲勞及抗?jié)B能力等。&l

78、t;/p><p>　　主要預(yù)防措施：一是盡量選用低熱或中熱水泥，如礦渣水泥、粉煤灰水泥等。二是減少水泥用量，將水泥用量盡量控制在450kg/m3以下。三是降低水灰比，一般混凝土的水灰比控制在0.6以下。四是改善骨料級(jí)配，摻加粉煤灰或高效減水劑等來減少水泥用量，降低水化熱。五是改善混凝土的攪拌加工工藝，降低混凝土的澆筑溫度。六是在混凝土中摻加一定量的具有減水、增塑、緩凝等作用的外加劑，改善混凝土拌合物的流動(dòng)性、保水性，

79、降低水化熱，推遲熱峰的出現(xiàn)時(shí)間。七是高溫季節(jié)澆筑時(shí)可以采用搭設(shè)遮陽板等輔助措施控制混凝土的溫升，降低澆筑混凝土的溫度。八是大體積混凝土的溫度應(yīng)力與結(jié)構(gòu)尺寸相關(guān)，混凝土結(jié)構(gòu)尺寸越大，溫度應(yīng)力越大，因此要合理安排施工工序，分層、分塊澆筑，以利于散熱，減小約束。九是在大體積混凝土內(nèi)部設(shè)置冷卻管道，通冷水或者冷氣冷卻，減小混凝土的內(nèi)外溫差。十是加強(qiáng)混凝土溫度的監(jiān)控，及時(shí)采取冷卻、保護(hù)措施。十一是預(yù)留溫度收縮縫。十二是減小約束，澆筑混凝土前宜在基

80、巖和老混凝土上鋪設(shè)5mm左右的砂墊層或使用瀝青等材料涂刷。十三是加強(qiáng)混凝土養(yǎng)護(hù)，混凝土澆筑后，及時(shí)用濕潤的草簾、麻片等覆蓋，并注意灑水養(yǎng)護(hù)，適當(dāng)延長養(yǎng)護(hù)時(shí)間，保證</p><p>　　5.化學(xué)反應(yīng)引起的裂縫及預(yù)防</p><p>　　堿骨料反應(yīng)裂縫和鋼筋銹蝕引起的裂縫是鋼筋混凝土結(jié)構(gòu)中最常見的由于化學(xué)反應(yīng)而引起的裂縫。</p><p>　　混凝土拌和后會(huì)產(chǎn)生一些堿性

81、離子，這些離子與某些活性骨料產(chǎn)生化學(xué)反應(yīng)并吸收周圍環(huán)境中的水而體積增大，造成混凝土酥松、膨脹開裂。這種裂縫一般出現(xiàn)中混凝土結(jié)構(gòu)使用期間，一旦出現(xiàn)很難補(bǔ)救，因此應(yīng)在施工中采取有效措施進(jìn)行預(yù)防。主要的預(yù)防措施：一是選用堿活性小的砂石骨料。二是選用低堿水泥和低堿或無堿的外加劑。三是選用合適的摻和料抑制堿骨料反應(yīng)。</p><p>　　由于混凝土澆筑、振搗不良或者是鋼筋保護(hù)層較薄，有害物質(zhì)進(jìn)入混凝土使鋼筋產(chǎn)生銹蝕，銹蝕的

82、鋼筋體積膨脹，導(dǎo)致混凝土脹裂，此種類型的裂縫多為縱向裂縫，沿鋼筋的位置出現(xiàn)。通常的預(yù)防措施有：一是保證鋼筋保護(hù)層的厚度。二是混凝土級(jí)配要良好。三是混凝土澆注要振搗密實(shí)。四是鋼筋表層涂刷防腐涂料。</p><p><b>　　裂縫處理</b></p><p>　　裂縫的出現(xiàn)不但會(huì)影響結(jié)構(gòu)的整體性和剛度，還會(huì)引起鋼筋的銹蝕、加速混凝土的碳化、降低混凝土的耐久性和抗疲勞、抗

83、滲能力。因此根據(jù)裂縫的性質(zhì)和具體情況我們要區(qū)別對(duì)待、及時(shí)處理，以保證建筑物的安全使用。</p><p>　　混凝土裂縫的修補(bǔ)措施主要有以下一些方法：表面修補(bǔ)法，灌漿、嵌縫封堵法，結(jié)構(gòu)加固法，混凝土置換法，電化學(xué)防護(hù)法以及仿生自愈合法。</p><p>　　表面修補(bǔ)法是一種簡單、常見的修補(bǔ)方法，它主要適用于穩(wěn)定和對(duì)結(jié)構(gòu)承載能力沒有影響的表面裂縫以及深進(jìn)裂縫的處理。通常的處理措施是在裂縫的表面

84、涂抹水泥漿、環(huán)氧膠泥或在混凝土表面涂刷油漆、瀝青等防腐材料，在防護(hù)的同時(shí)為了防止混凝土受各種作用的影響繼續(xù)開裂，通常可以采用在裂縫的表面粘貼玻璃纖維布等措施。</p><p>　　1、灌漿、嵌縫封堵法</p><p>　　灌漿法主要適用于對(duì)結(jié)構(gòu)整體性有影響或有防滲要求的混凝土裂縫的修補(bǔ)，它是利用壓力設(shè)備將膠結(jié)材料壓入混凝土的裂縫中，膠結(jié)材料硬化后與混凝土形成一個(gè)整體，從而起到封堵加固的目的

85、。常用的膠結(jié)材料有水泥漿、環(huán)氧樹脂、甲基丙烯酸酯、聚氨酯等化學(xué)材料。</p><p>　　嵌縫法是裂縫封堵中最常用的一種方法，它通常是沿裂縫鑿槽，在槽中嵌填塑性或剛性止水材料，以達(dá)到封閉裂縫的目的。常用的塑性材料有聚氯乙烯膠泥、塑料油膏、丁基橡膠等等；常用的剛性止水材料為聚合物水泥砂漿。</p><p><b>　　2、結(jié)構(gòu)加固法</b></p><

86、;p>　　當(dāng)裂縫影響到混凝土結(jié)構(gòu)的性能時(shí)，就要考慮采取加固法對(duì)混凝土結(jié)構(gòu)進(jìn)行處理。結(jié)構(gòu)加固中常用的主要有以下幾種方法：加大混凝土結(jié)構(gòu)的截面面積，在構(gòu)件的角部外包型鋼、采用預(yù)應(yīng)力法加固、粘貼鋼板加固、增設(shè)支點(diǎn)加固以及噴射混凝土補(bǔ)強(qiáng)加固。</p><p><b>　　3、混凝土置換法</b></p><p>　　混凝土置換法是處理嚴(yán)重?fù)p壞混凝土的一種有效方法，此方法

87、是先將損壞的混凝土剔除，然后再置換入新的混凝土或其他材料。常用的置換材料有：普通混凝土或水泥砂漿、聚合物或改性聚合物混凝土或砂漿。</p><p><b>　　4、電化學(xué)防護(hù)法</b></p><p>　　電化學(xué)防腐是利用施加電場在介質(zhì)中的電化學(xué)作用，改變混凝土或鋼筋混凝土所處的環(huán)境狀態(tài)，鈍化鋼筋，以達(dá)到防腐的目的。陰極防護(hù)法、氯鹽提取法、堿性復(fù)原法是化學(xué)防護(hù)法中常用

88、而有效的三種方法。這種方法的優(yōu)點(diǎn)是防護(hù)方法受環(huán)境因素的影響較小，適用鋼筋、混凝土的長期防腐，既可用于已裂結(jié)構(gòu)也可用于新建結(jié)構(gòu)。</p><p><b>　　5、仿生自愈合法</b></p><p>　　仿生自愈合法是一種新的裂縫處理方法，它模仿生物組織對(duì)受創(chuàng)傷部位自動(dòng)分泌某種物質(zhì)，而使創(chuàng)傷部位得到愈合的機(jī)能，在混凝土的傳統(tǒng)成分中加入某些特殊成分（如含粘結(jié)劑的液芯纖維或

89、膠囊），在混凝土內(nèi)部形成智能型仿生自愈合神經(jīng)網(wǎng)絡(luò)系統(tǒng)，當(dāng)混凝土出現(xiàn)裂縫時(shí)分泌出部分液芯纖維可使裂縫重新愈合。</p><p><b>　　結(jié) 論</b></p><p>　　裂縫是混凝土結(jié)構(gòu)中普遍存在的一種現(xiàn)象，它的出現(xiàn)不僅會(huì)降低建筑物的抗?jié)B能力，影響建筑物的使用功能，而且會(huì)引起鋼筋的銹蝕，混凝土的碳化，降低材料的耐久性，影響建筑物的承載能力，因此要對(duì)混凝土裂縫進(jìn)行認(rèn)