建筑施工混凝土裂縫 畢業(yè)論文文獻(xiàn)翻譯

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1、 Building construction concrete crack Abstract The crack problem of concrete is a widespread existence but again difficult in solve of engineering actual problem, this text carried on a study analysis to a little bit familiar crack problem in the concrete engineering. Keyword:Concrete crack

2、 Foreword Concretes ising 1 kind is anticipate by the freestone bone, cement, water and other mixture but formation of the in addition material of quality brittleness not and all material.Because the concrete construction transform with oneself, control etc. a series problem, harden model of in

3、the concrete existence numerous tiny hole, spirit cave and tiny crack, is exactly because these beginning start blemish of existence just make the concrete present one some not and all the characteristic of quality.The tiny crack is a kind of harmless crack and accept concrete heavy, defend Shen and

4、 a little bit other use function not a creation to endanger.But after the concrete be subjected to lotus carry, difference in temperature etc. function, tiny crack would continuously of expand with connect, end formation we can see without the aid of instruments of macro view the crack be also the c

5、rack that the concrete often say in the engineering. 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 sink etc. reason cause of crack;Have outside carry the crack that the

6、function cause;Protected environment not appropriate the crack etc. caused with chemical effect.Want differentiation to treat in the actual engineering, workout a problem according to the actual circumstance. In the concrete engineering the familiar crack and the prevention 1.Stem Suo crack an

7、d prevention 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 stem Suo, and this kind of constringency is cant negative.Stem Suo crack of

8、 the creation be main is because of concrete inside outside humidity evaporate degree dissimilarity but cause to transform dissimilarity of result:The concrete is subjected to exterior condition of influence, surface humidity loss lead quick, transform bigger, inner part degree of humidity variety s

9、maller transform smaller, bigger surface stem the Suo transform to be subjected to concrete inner part control, creation more big pull should dint but creation crack.The relative humidity is more low, cement syrup body stem Suo more big, stem the Suo crack be more easy creation.Stem the Suo crack is

10、 much surface parallel lines form or the net shallow thin crack, width many between 0.05-0.2 mm, the flat surface part much see in the big physical volume concrete and follow it more in thinner beam plank short to distribute.Stem Suo crack usually the anti- Shen of influence concrete, cause the dura

11、ble of the rust eclipse influence concrete of reinforcing bar, under the function of the water pressure dint would creation the water power split crack influence concrete of loading dint etc..Concrete stem the Suo be main with water ash of the concrete ratio, the dosage of the composition, cement of

12、 cement, gather to anticipate of the dosage of the property and dosage, in addition etc. relevant. 2.The Su constringency crack and prevention Su constringency is the concrete is before condense, surface because of lose water quicker but creation of constringency.The Su constringency crack is

13、general at dry heat or strong wind the weather appear, cracks 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 reach to a 2-3 m, breadth 1-5 mm.It creat

14、ion of main reason is:The concrete is eventually almost having no strength or strength before the Ning very small, perhaps concrete just eventually Ning but strength very hour, be subjected to heat or compare strong wind dint of influence, the concrete surface lose water to lead quick, result in in

15、the capillary creation bigger negative press but make a concrete physical volume sharply constringency, but at this time the strength of concrete again cant resist its constringency, therefore creation cracked.The influence concrete Su constringency open the main factor of crack to have water ash ra

16、tio, concrete of condense time, environment temperature, wind velocity, relative humidity...etc.. 3.Sink to sink crack and prevention 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

17、 water but result in the asymmetry 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 template prop up at jelly soil up, jelly the soil turn jel

18、ly empress creation asymmetry to sink to decline and cause concrete structure creation crack.This kind crack many is deep enter or pierce through sex crack, it alignment have something to do with sinking to sink a circumstance, general follow with ground perpendicular or present 30 s-45 Cape direct

19、ion development, bigger sink to sink crack, usually have certain of wrong, crack width usually with sink to decline quantity direct proportion relation.Crack width under the influence of temperature variety smaller.The foundation after transform stability sink to sink crack also basic tend in stabil

20、ity. 4.Temperature crack and prevention 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.Concrete after sprinkling to build, in the hardening the process, cement water t

21、urn 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 a calories of 17500-27500 kJ and make concrete internal thus the temperature rise to reach to 70 ℃ or so even higher)Because the physical volume of concr

22、ete be more big, a great deal of of water turn hot accumulate at the concrete inner part but not easy send forth, cause inner part the temperature hoick, but the concrete surface spread hot more quick, so formation inside outside of bigger difference in temperature, the bigger difference in temperat

23、ure result in inner part and exterior hot the degree of the bulge cold Suo dissimilarity, make concrete surface creation certain of pull should dint.When pull should dint exceed the anti- of concrete pull strength extreme limit, concrete surface meeting creation crack, this kind of crack much occurr

24、ence after the concrete under construction period.In the concrete of under construction be difference in temperature variety more big, perhaps is a concrete to be subjected to assault of cold wave etc., will cause concrete surface the temperature sharply descend, but creation constringency, surface

25、constringency of the concrete be subjected to inner part concrete of control, creation very big of pull should dint but creation crack, this kind of crack usually just in more shallow scope of the concrete surface creation. Conclusion The crack is widespread in the concrete structure existence of

26、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 of reinforcing bar, the carbonization of concrete, lower the durable of material, influence building of loading ability, so want to carr

27、y on to the concrete crack earnest research, differentiation treat, adoption reasonable of the method carry on processing, and at under construction adopt various valid of prevention measure to prevention crack of emergence and development, assurance building and Gou piece safety, stability work.

28、 From《CANADIAN JOURNAL OF CIVIL ENGINEERING》 建筑施工混凝土裂縫 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，本文對混凝土工程中常見的一些裂縫問題進(jìn)行了探討分析。 關(guān)鍵詞：混凝土 裂縫 前言 　　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

29、差等作用之后，微裂縫就會不斷的擴(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。 　　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)別對待，根據(jù)實(shí)際情況解決問題。 　　混凝土工程中常見裂縫: 　　1.干縮裂縫 　　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

30、水分損失過快，變形較大，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產(chǎn)生水力劈裂影響混凝土的承載力等等?；炷粮煽s主要和混凝土的水灰比、水泥的成分、水泥的用量、集料的性質(zhì)和用量、外加劑的用量等有關(guān)。 　　2.塑性收縮裂縫 　　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

31、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1-5mm.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、相對濕度等等。 　　　3.沉陷裂縫 　　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；

32、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響較小。地基變形穩(wěn)定之后，沉陷裂縫也基本趨于穩(wěn)定。 　　　　4.溫度裂縫 　　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?；炷翝仓?，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

33、-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?！? 　　結(jié) 論 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)不僅會降低建筑物的抗?jié)B能力，影響建筑物的使用功能，而且會引起鋼筋的銹蝕，混凝土的碳化，降低材料的耐久性，影響建筑物的承載能力，因此要對混凝土裂縫進(jìn)行認(rèn)真研究、區(qū)別對待，采用合理的方法進(jìn)行處理，并在施工中采取各種有效的預(yù)防措施來預(yù)防裂縫的出現(xiàn)和發(fā)展，保證建筑物和構(gòu)件安全、穩(wěn)定地工作。