外文翻譯---混凝土施工溫度與裂縫的探討

1、<p><b>　　外文文獻(xiàn)翻譯</b></p><p><b>　　英文文獻(xiàn)：</b></p><p>　　Discussion on the construction temperature and cracks of concrete</p><p>　　Abstract: Based upon analy

2、sis of the reasons caused the cracks of concrete the temperature stress of concrete is studied.The control measures of temperature stress as well as preventive measures of cracks are elaborated in detail in order to avoi

3、d production of cracks in construction process to ensure construction quality.</p><p>　　Key words: concrete ,temperature stress, crack, construction</p><p>　　In the mass concrete, temperature st

4、ress and temperature control system has great significance. There are two reasons:1)In the construction of concrete it often appear temperature cracks, which affects the integrity and durability of the structure;2) In th

5、e operation process, the temperature changes have influence on stress state of structure which cannot be ignored. Since temperature crack caused in the construction is mainly met , the causes of cracks and Processing me

6、asures in the constructi</p><p>　　1.the causes of the cracks </p><p>　　Cracks in concrete are a variety of reasons, mainly temperature and humidity changes, brittle and uneven concrete, as well

7、 as the structure is irrational, failure of raw materials (such as alkali-aggregate reaction), template deformation, and so on the basis of differential settlement.</p><p>　　The concrete to harden off a larg

8、e number of cement during the hydration heat, the internal temperature rising on the surface caused by tensile stress. Late in the cooling process, due to coagulation on the basis of or be bound by the old, will emerge i

9、n the concrete tensile stress. Lower temperatures in the concrete surface will be a lot of tensile stress. When the tensile stress beyond the capacity of concrete crack, the cracks will appear. A number of concrete chang

10、es in the internal humidity</p><p>　　2. thermal stress analysis</p><p>　　According to the formation of thermal stress can be divided into the following three stages:</p><p>　　early:

11、 Since the beginning of pouring concrete to cement the end of exothermic basic general about 30 days. Two characteristics of this stage, first, to release a large number of cement hydration heat, and the other is the ela

12、stic modulus of coagulation dramatic changes. Modulus of elasticity as a result of changes within this period in the formation of residual stress in the concrete.</p><p>　　(2) medium-term: from the basic rol

13、e of cement heat until the end of the stable temperature of the concrete cooling time, during this period, the temperature stress was mainly due to cooling and the outside concrete caused by temperature changes, stress a

14、nd early formation of these residual stress superposition phase, during which the coagulation of the elastic modulus changed little.</p><p>　　(3) late: concrete completely cooling period after the operation.

15、 Thermal stress is mainly caused by external temperature changes, the stress and the first two-phase superposition of residual stress.</p><p>　　Under the thermal stress caused by the reasons can be divided i

16、nto two categories:</p><p>　　(1) self-stress: there is no constraint on the border or completely static structure, if the internal temperature distribution is nonlinear, due to structural constraints arising

17、 from their co-temperature stress. For example, the conversion layer of its relatively larger size, concrete cooling surface temperature low, the internal temperatures are high, the surface tensile stress, compressive st

18、ress appears in the middle.</p><p>　　(2) bound by stress: the structure of all or part of the boundary bound by the outside world can not be free-form deformation caused by stress. Roof box, such as concrete

19、 and concrete barrier.</p><p>　　Both the temperature and the concrete stress is often caused by shrinkage of the combined effect of stress.</p><p>　　Known to be in accordance with an accurate an

20、alysis of the temperature of the thermal stress distribution, size is a more complex task. In most cases, the need to rely on model test or numerical calculation. Creep of concrete so that the temperature there is consid

21、erable stress relaxation, thermal stress calculation, we must consider the effects of creep, is no longer calculated in detail here.</p><p>　　3. temperature control and measures to prevent the cracks</p&g

22、t;<p>　　In order to prevent cracking, reduce the thermal stress can control the conditions of temperature and to improve the binding of two aspects.</p><p>　　Temperature control measures are as follow

23、s:</p><p>　　(1) used to improve the aggregate gradation, dry hard concrete, mixed mixture, add air-entraining agent or plasticizer, etc. measures to reduce the amount of cement concrete;</p><p>

24、　　(2) mixing concrete by adding water or cooling water will be gravel and pouring concrete to reduce the temperature;</p><p>　　(3) pouring hot days to reduce the pouring of concrete thickness, the use of pou

25、ring heat levels;</p><p>　　(4) laid in concrete water pipes, access to cold water to cool;</p><p>　　(5) the provisions of reasonable time, the temperature drop when the surface insulation, concr

26、ete surface in order to avoid a sharp temperature gradient;</p><p>　　(6) Construction of long-term exposure to block the surface of the concrete pouring, or thin-walled structures, thermal insulation in the

27、cold season to take measures;</p><p>　　Measures to improve the constraints are:</p><p>　　(1) a reasonable sub-block joints;</p><p>　　(2) basis to avoid too much ups and downs;</p

28、><p>　　(3) reasonable arrangements for the construction process, to avoid excessive side elevation and long-term exposure;</p><p>　　In addition, to improve the performance of concrete to improve th

29、e anti-cracking ability, to strengthen the conservation, to prevent surface drying, in particular, is to ensure the quality of concrete is very important to prevent cracks, should pay special attention to avoid cross-cra

30、cks appears to restore the integrity of its structure it is very difficult, so the construction should be to prevent the occurrence of cross-cutting the main crack.</p><p>　　In concrete construction, in orde

31、r to increase the turnover rate of the template, often require new pouring concrete as soon as possible. When the concrete temperature is higher than the temperature should be appropriate to consider time, so as to avoid

32、 the early cracks in the concrete surface. New pouring early, a lot of the surface tensile stress, a "temperature shock" phenomenon. Concrete pouring in the early heat of hydration as a result of the disseminat

33、ion of the surface caused by a large </p><p>　　Tensile stress to reach the surface of great value, there is the danger of lead to cracks, but if in a timely manner after the removal of the template on the su

34、rface coverage of a light insulating material, such as foam sponge and so on, have a concrete surface to prevent excessive tensile stress, with significant results.</p><p>　　Reinforced concrete on the large

35、volume of thermal stress has little effect because the large volume of concrete reinforced with a very low rate. Only on the general impact of reinforced concrete. Not too high in temperature and stress below the yield l

36、imit under the condition of the properties of steel is stable, and with the stress, time and temperature has nothing to do. Linear expansion coefficient of steel and concrete linear expansion coefficient difference betwe

37、en the small changes in tem</p><p>　　, Want to use in reinforced concrete to prevent the emergence of small cracks is difficult. However, after the reinforced structure of the number of cracks in general has

38、 become more than a small distance, a smaller width and depth. And if the diameter of steel thin and close spacing, the crack resistance of concrete to enhance the effect of better. Concrete and reinforced concrete struc

39、ture of the surface often occur cracks in thin and shallow, most of them belonging to shrinkage cracks. While </p><p>　　In order to ensure the quality of concrete to prevent cracking and improve the durabili

40、ty of concrete, the proper use of admixtures is also one of the measures to reduce cracking. Such as the use of anti-cracking agent and water, in practice, its major role in concluding as follows:</p><p>　　(

41、1) the existence of a large number of pores in the concrete that, after evaporation of water generated by capillary capillary tension, deformation of the concrete shrinkage. Pores increased capillary diameter can reduce

42、the surface tension, but would reduce the strength of concrete.</p><p>　　(2) the impact of water-cement ratio is an important factor for concrete shrinkage, the use of anti-cracking agent can reduce water co

43、nsumption reduced by 25% concrete.</p><p>　　(3) the amount of cement concrete is also an important factor in shrinkage, water addition and subtraction mixed concrete cracking agent in maintaining the strengt

44、h of concrete under the condition of 15 percent can reduce the amount of cement, aggregate size, by increasing the amount to supplement.</p><p>　　(4) anti-cracking agent and water can improve the consistency

45、 of cement slurry to reduce the bleeding of concrete, reduce shrinkage deformation Shen.</p><p>　　(5) to improve and cement bonded aggregate, and enhance the anti-cracking performance of concrete.</p>

46、<p>　　(6) concrete bound in the contraction produced by tensile stress, when the tensile stress is greater than the tensile strength of concrete will be produced when the cracks. Water-reducing agent can be an effe

47、ctive anti-cracking of the concrete tensile strength to increase, a substantial increase in anti-cracking performance of concrete.</p><p>　　(7) mixing-compacting concrete admixtures can, and can effectively

48、improve the carbonation resistance of concrete to reduce the carbonation shrinkage.</p><p>　　(8)-doped water-reducing agent after the concrete cracking retardation time due, in the effective prevention of th

49、e rapid hydration heat of cement based on cement to avoid long-term result of non-condensable increase plastic shrinkage.</p><p>　　(9)-doped workability of concrete admixtures, and easy to find flat surfaces

50、 to form a micro-membrane to reduce evaporation and reduce drying shrinkage.</p><p>　　Many have a retarding admixture to increase the workability and improve the function of plasticity, we in engineering pra

51、ctice in this area should be more contrast and research experiments than simply relying on external conditions to improve may be even more simple and economic.</p><p>　　4. early concrete conservation</p&g

52、t;<p>　　Practice has proved that the common concrete cracks, the majority of surface cracks at different depths, mainly because of the temperature gradient caused by the cold temperature region is also vulnerable

53、to a sharp fall in the formation of cracks. Insulation so that the concrete surface to prevent early cracking is particularly important.</p><p>　　Thermal stress from the point of view, the insulation should

54、meet the following requirements:</p><p>　　1) to prevent the concrete inside and outside the concrete surface temperature difference and gradient, to prevent surface cracks.</p><p>　　2) to preven

55、t the concrete super-cold, it should be possible to make concrete the construction period of not less than the minimum temperature of concrete used for the stability of the temperature.</p><p>　　3) to preven

56、t cold-old concrete in order to reduce the concrete between the old and new constraints.</p><p>　　Early concrete conservation, the main objective is to maintain the appropriate temperature and humidity condi

57、tions in order to achieve the effect of two aspects, on the one hand, the concrete from adverse temperature and humidity deformation invasion to prevent the harmful and drying shrinkage. On the one hand, to enable the sm

58、ooth progress of cement hydration, with a view to meet the design capacity of the strength and crack resistance.</p><p>　　Appropriate conditions of temperature and humidity are interrelated. Coagulation on t

59、he insulation often has the effect of moisture.</p><p>　　Theoretical analysis of fresh concrete contained in the water fully meets the requirements of cement hydration and more than. However, due to evaporat

60、ion and other factors often cause water loss, thereby delay or prevent the hydration of cement, concrete surface and most likely to be directly affected by such a negative impact. Concrete pouring, therefore the first fe

61、w days after the critical period of conservation in the construction should pay attention to.</p><p>　　5. concluding remarks</p><p>　　Above the temperature of concrete and cracks in the construc

62、tion of the relation between theory and practice of the preliminary study, although the academic community about the causes of cracks in concrete and calculation methods are different theories, but specific measures to p

63、revent and improve the opinion it is quite uniform At the same time, the application in practice is also a relatively good effect, concrete construction and more depends on our observation, and more, when compared to mul

64、</p><p><b>　　中文翻譯：</b></p><p>　　混凝土施工溫度與裂縫的探討</p><p>　　摘要：對(duì)施工中混凝土裂縫的成因進(jìn)行了探討，分析了混凝土的溫度應(yīng)力，詳細(xì)闡述了溫度應(yīng)力的控制和防止裂縫的措施，以避免混凝土產(chǎn)生裂縫，從而保證混凝土的施工質(zhì)量。</p><p>　　關(guān)鍵詞：混凝土，溫度應(yīng)力，

65、裂縫，施工</p><p>　　在大體積混凝土中,溫度應(yīng)力及溫度控制具有重要意義。這主要是由于兩方面的原因：1)在施工中混凝土常常出現(xiàn)溫度裂縫，影響到結(jié)構(gòu)的整體性和耐久性;2)在運(yùn)轉(zhuǎn)過程中，溫度變化對(duì)結(jié)構(gòu)的應(yīng)力狀態(tài)具有顯著的不容忽視的影響。由于遇到的主要是施工中的溫度裂縫，因此下面僅對(duì)施工中混凝土裂縫的成因和處理措施做一探討。</p><p><b>　　1．裂縫的原因 

66、;</b></p><p>　　混凝土中產(chǎn)生裂縫有多種原因，主要是溫度和濕度的變化，混凝土的脆性和不均勻性，以及結(jié)構(gòu)不合理，原材料不合格（如堿骨料反應(yīng)），模板變形，基礎(chǔ)不均勻沉降等。</p><p>　　混凝土硬化期間水泥放出大量水化熱，內(nèi)部溫度不斷上升，在表面引起拉應(yīng)力。后期在降溫過程中，由于受到基礎(chǔ)或老混凝上的約束，又會(huì)在混凝土內(nèi)部出現(xiàn)拉應(yīng)力。氣溫的降低也會(huì)在混凝土表面引起

67、很大的拉應(yīng)力。當(dāng)這些拉應(yīng)力超出混凝土的抗裂能力時(shí)，即會(huì)出現(xiàn)裂縫。許多混凝土的內(nèi)部濕度變化很小或變化較慢，但表面濕度可能變化較大或發(fā)生劇烈變化。如養(yǎng)護(hù)不周、時(shí)干時(shí)濕，表面干縮形變受到內(nèi)部混凝土的約束，也往往導(dǎo)致裂縫?；炷潦且环N脆性材料，抗拉強(qiáng)度是抗壓強(qiáng)度的1／10左右，短期加荷時(shí)的極限拉伸變形只有（0.6～1.0）×104，長(zhǎng)期加荷時(shí)的極限位伸變形也只有（1.2～2.0）×104.由于原材料不均勻，水灰比不穩(wěn)定，及運(yùn)

68、輸和澆筑過程中的離析現(xiàn)象，在同一塊混凝土中其抗拉強(qiáng)度又是不均勻的，存在著許多抗拉能力很低，易于出現(xiàn)裂縫的薄弱部位。在鋼筋混凝土中，拉應(yīng)力主要是由鋼筋承擔(dān)，混凝土只是承受壓應(yīng)力。在素混凝土內(nèi)或鋼筋混凝上的邊緣部位如果結(jié)構(gòu)內(nèi)出現(xiàn)了拉應(yīng)力，則須依靠混凝土自身承擔(dān)。一般設(shè)計(jì)中均要求不出現(xiàn)拉應(yīng)力或者只出現(xiàn)很小的拉應(yīng)力。但是在施工中混凝土由最高溫度冷卻到運(yùn)轉(zhuǎn)時(shí)期的穩(wěn)定溫度，往往在混凝土內(nèi)部引起相當(dāng)大的拉應(yīng)力。有時(shí)</p><p&

69、gt;　　根據(jù)溫度應(yīng)力的形成過程可分為以下三個(gè)階段：</p><p>　　1）早期：自澆筑混凝土開始至水泥放熱基本結(jié)束，一般約30天。這個(gè)階段的兩個(gè)特征，一是水泥放出大量的水化熱，二是混凝上彈性模量的急劇變化。由于彈性模量的變化，這一時(shí)期在混凝土內(nèi)形成殘余應(yīng)力。 2）中期：自水泥放熱作用基本結(jié)束時(shí)起至混凝土冷卻到穩(wěn)定溫度時(shí)止，這個(gè)時(shí)期中，溫度應(yīng)力主要是由于混凝土的冷卻及外界氣溫變化所引起，這些應(yīng)力與早期形

70、成的殘余應(yīng)力相疊加，在此期間混凝上的彈性模量變化不大。 3）晚期：混凝土完全冷卻以后的運(yùn)轉(zhuǎn)時(shí)期。溫度應(yīng)力主要是外界氣溫變化所引起，這些應(yīng)力與前兩種的殘余應(yīng)力相迭加。根據(jù)溫度應(yīng)力引起的原因可分為兩類： （1）自生應(yīng)力：邊界上沒有任何約束或完全靜止的結(jié)構(gòu)，如果內(nèi)部溫度是非線性分布的，由于結(jié)構(gòu)本身互相約束而出現(xiàn)的溫度應(yīng)力。例如，轉(zhuǎn)換層其結(jié)構(gòu)尺寸相對(duì)較大，混凝土冷卻時(shí)表面溫度低，內(nèi)部溫度高，在表面出現(xiàn)拉應(yīng)力，在中間出現(xiàn)壓應(yīng)力。

71、</p><p>　　（2）約束應(yīng)力：結(jié)構(gòu)的全部或部分邊界受到外界的約束，不能自由變形而引起的應(yīng)力。如箱梁頂板混凝土和護(hù)欄混凝土。這兩種溫度應(yīng)力往往和混凝土的干縮所引起的應(yīng)力共同作用。要想根據(jù)已知的溫度準(zhǔn)確分析出溫度應(yīng)力的分布、大小是一項(xiàng)比較復(fù)雜的工作。在大多數(shù)情況下，需要依靠模型試驗(yàn)或數(shù)值計(jì)算?；炷恋男熳兪箿囟葢?yīng)力有相當(dāng)大的松馳，計(jì)算溫度應(yīng)力時(shí)，必須考慮徐變的影響，具體計(jì)算這里就不再細(xì)述。 3．溫度的

72、控制和防止裂縫的措施</p><p>　　為了防止裂縫，減輕溫度應(yīng)力可以從控制溫度和改善約束條件兩個(gè)方面著手?？刂茰囟鹊拇胧┤缦拢?1）采用改善骨料級(jí)配，用干硬性混凝土，摻混合料，加引氣劑或塑化劑等措施以減少混凝土中的水泥用量； 2）拌合混凝土?xí)r加水或用水將碎石冷卻以降低混凝土的澆筑溫度； 3）熱天澆筑混凝土?xí)r減少澆筑厚度，利用澆筑層面散熱； 4）在混凝土中埋設(shè)水管，通入冷水降溫；

73、 5）規(guī)定合理的拆模時(shí)間，氣溫驟降時(shí)進(jìn)行表面保溫，以免混凝土表面發(fā)生急劇的溫度梯度； 6）施工中長(zhǎng)期暴露的混凝土澆筑塊表面或薄壁結(jié)構(gòu)，在寒冷季節(jié)采取保溫措施； 改善約束條件的措施是：</p><p>　?。?）合理地分縫分塊；（2）避免基礎(chǔ)過大起伏；（3）合理的安排施工工序，避免過大的高差和側(cè)面長(zhǎng)期暴露；</p><p>　　此外，改善混凝土的性能，提高抗裂能力

74、，加強(qiáng)養(yǎng)護(hù)，防止表面干縮，特別是保證混凝土的質(zhì)量對(duì)防止裂縫是十分重要，應(yīng)特別注意避免產(chǎn)生貫穿裂縫，出現(xiàn)后要恢復(fù)其結(jié)構(gòu)的整體性是十分困難的，因此施工中應(yīng)以預(yù)防貫穿性裂縫的發(fā)生為主。 </p><p>　　在混凝土的施工中，為了提高模板的周轉(zhuǎn)率，往往要求新澆筑的混凝土盡早拆模。當(dāng)混凝土溫度高于氣溫時(shí)應(yīng)適當(dāng)考慮拆模時(shí)間，以免引起混凝土表面的早期裂縫。新澆筑早期拆模，在表面引起很大的拉應(yīng)力，出現(xiàn)“溫度沖擊”現(xiàn)象。在混凝土

75、澆筑初期，由于水化熱的散發(fā)，表面引起相當(dāng)大的拉應(yīng)力，此時(shí)表面溫度亦較氣溫為高，此時(shí)拆除模板，表面溫度驟降，必然引起溫度梯度，從而在表面附加一拉應(yīng)力，與水化熱應(yīng)力迭加，再加上混凝土干縮，表面的拉應(yīng)力達(dá)到很大的數(shù)值，就有導(dǎo)致裂縫的危險(xiǎn)，但如果在拆除模板后及時(shí)在表面覆蓋一輕型保溫材料，如泡沫海棉等，對(duì)于防止混凝土表面產(chǎn)生過大的拉應(yīng)力，具有顯著的效果。 </p><p>　　加筋對(duì)大體積混凝土的溫度應(yīng)力影響很小，因?yàn)榇篌w

76、積混凝土的含筋率極低。只是對(duì)一般鋼筋混凝土有影響。在溫度不太高及應(yīng)力低于屈服極限的條件下，鋼的各項(xiàng)性能是穩(wěn)定的，而與應(yīng)力狀態(tài)、時(shí)間及溫度無(wú)關(guān)。鋼的線脹系數(shù)與混凝土線脹系數(shù)相差很小，在溫度變化時(shí)兩者間只發(fā)生很小的內(nèi)應(yīng)力。由于鋼的彈性模量為混凝土彈性模量的7-15倍，當(dāng)內(nèi)混凝土應(yīng)力達(dá)到抗拉強(qiáng)度而開裂時(shí)，鋼筋的應(yīng)力將不超過100-200kg／cm2..因此，在混凝土中想要利用鋼筋來防止細(xì)小裂縫的出現(xiàn)很困難。但加筋后結(jié)構(gòu)內(nèi)的裂縫一般就變得數(shù)目多

77、、間距小、寬度與深度較小了。而且如果鋼筋的直徑細(xì)而間距密時(shí)，對(duì)提高混凝土抗裂性的效果較好?；炷梁弯摻罨炷两Y(jié)構(gòu)的表面常常會(huì)發(fā)生細(xì)而淺的裂縫，其中大多數(shù)屬于干縮裂縫。雖然這種裂縫一般都較淺，但它對(duì)結(jié)構(gòu)的強(qiáng)度和耐久性仍有一定的影響。 </p><p>　　為保證混凝土工程質(zhì)量，防止開裂，提高混凝土的耐久性，正確使用外加劑也是減少開裂的措施之一。</p><p>　　例如使用減水防裂劑，在實(shí)踐

78、中總結(jié)出其主要作用為：1）混凝土中存在大量毛細(xì)孔道，水蒸發(fā)后毛細(xì)管中產(chǎn)生毛細(xì)管張力，使混凝土干縮變形。增大毛細(xì)孔徑可降低毛細(xì)管表面張力，但會(huì)使混凝土強(qiáng)度降低。2）水灰比是影響混凝土收縮的重要因素，使用減水防裂劑可使混凝土用水量減少25％。3）水泥用量也是混凝土收縮率的重要因素，摻加減水防裂劑的混凝土在保持混凝土強(qiáng)度的條件下可減少15％的水泥用量，其體積用增加骨料用量來補(bǔ)充。4）減水防裂劑可以改善水泥漿的稠度，減少混凝土泌水，減少

79、沉縮變形。5）提高水泥漿與骨料的粘結(jié)力，提高的混凝土抗裂性能。6）混凝土在收縮時(shí)受到約束產(chǎn)生拉應(yīng)力，當(dāng)拉應(yīng)力大于混凝土抗拉強(qiáng)度時(shí)裂縫就會(huì)產(chǎn)生。減水防裂劑可有效的提高的混凝土抗拉強(qiáng)度，大幅提高混凝土的抗裂性能。7）摻加外加劑可使混凝土密實(shí)性好，可有效地提高混凝土的抗碳化性，減少碳化收縮。8）摻減水防裂劑后混凝土緩凝時(shí)間適當(dāng)，在有效防止水泥迅速水化放熱基礎(chǔ)上，避免因水泥長(zhǎng)期不凝而帶來的塑性收縮增加。9）摻外加劑混凝土和易性好，表面

80、易摸平，形成微膜，減少水分蒸發(fā)，減少干燥收縮.許多外加劑都有緩凝、增加和易性、改善塑性的功能</p><p>　　實(shí)踐證明，混凝土常見的裂縫，大多數(shù)是不同深度的表面裂縫，其主要原因是溫度梯度造成寒冷地區(qū)的溫度驟降也容易形成裂縫。因此說混凝土的保溫對(duì)防止表面早期裂縫尤其重要。從溫度應(yīng)力觀點(diǎn)出發(fā)，保溫應(yīng)達(dá)到下述要求： 1）防止混凝土內(nèi)外溫度差及混凝土表面梯度，防止表面裂縫。 2）防止混凝土超冷，應(yīng)

81、該盡量設(shè)法使混凝土的施工期最低溫度不低于混凝土使用期的穩(wěn)定溫度。 3）防止老混凝土過冷，以減少新老混凝土間的約束?；炷恋脑缙陴B(yǎng)護(hù)，主要目的在于保持適宜的溫濕條件，以達(dá)到兩個(gè)方面的效果，一方面使混凝土免受不利溫、濕度變形的侵襲，防止有害的冷縮和干縮。一方面使水泥水化作用順利進(jìn)行，以期達(dá)到設(shè)計(jì)的強(qiáng)度和抗裂能力。 </p><p>　　適宜的溫濕度條件是相互關(guān)聯(lián)的?；炷系谋卮胧┏３Ｒ灿斜竦男Ч?。從理

82、論上分析，新澆混凝土中所含水分完全可以滿足水泥水化的要求而有余。但由于蒸發(fā)等原因常引起水分損失，從而推遲或防礙水泥的水化，表面混凝土最容易而且直接受到這種不利影響。因此混凝土澆筑后的最初幾天是養(yǎng)護(hù)的關(guān)鍵時(shí)期，在施工中應(yīng)切實(shí)重視起來。 5．結(jié)束語(yǔ) </p><p>　　以上對(duì)混凝土的施工溫度與裂縫之間的關(guān)系進(jìn)行了理論和實(shí)踐上的初步探討，雖然學(xué)術(shù)界對(duì)于混凝土裂縫的成因和計(jì)算方法有不同的理論，但對(duì)于具體的預(yù)防和