外文翻译--低热硅酸盐水泥混凝土的抗裂性能

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1、外文资料翻译Anti-Crack Performance of Low-HeatPortland Cement ConcreteAbstract: The properties of low-heat Portland cement concrete(LHC) were studied in detail. The experimental results show that the LHC concrete has characteristics of a higher physical mechanical behavior, deformation and durability. Com

2、pared with moderate-heat Portland cement(MHC), the average hydration heat of LHC concrete is reduced by about 17.5%. Under same mixing proportion, the adiabatic temperature rise of LHC concrete was reduced by 2 -3,and the limits tension of LHC concrete was increased by 1010-6-1510-6 than that of MHC

3、. Moreover, it is indicated that LHC concrete has a better anti-crack behavior than MHC concrete.Key words: low-heat portland cement; mass concrete; high crack resistance; moderate-heat portland cement1 IntroductionThe investigation on crack of mass concrete is a hot problem to which attention has b

4、een paid for a long time. The cracks of the concrete are formed by multi-factors, but they are mainly caused by thermal displacements in mass concrete1-3. So the key technology on mass concrete is how to reduce thermal displacements and enhance the crack resistance of concrete.As well known, the hyd

5、ration heat of bonding materials is the main reason that results in the temperature difference between outside and inside of mass concrete4,5. In order to reduce the inner temperature of hydroelectric concrete, several methods have been proposed in mix proportion design. These include using moderate

6、-heat portland cement (MHC), reducing the content of cement, and increasing the Portland cement (OPC), MHC has advantages such as low heat of hydration, high growth rate of long-term strength, etc6,7. So it is more reasonable to use MHC in application of mass concrete.Low-heat portland cement (LHC),

7、 namely highbelite cement is currently attracting a great deal of interest worldwide. This is largely due to its lower energy consumption and CO2 emission in manufacture than conventional Portland cements. LHC has a lot of noticeable properties, such as low heat of hydration excellent durability, et

8、c, so the further study continues to be important8-10. The long-term strength of C2S can approach to or even exceed that of C3S11. In addition, C2S has a series of characteristics superior to C3S. These include the low content of CaO, low hydration heat, good toughness, compact hydration products, e

9、xcellent resistances to chemical corrosion, little dry shrinkage, etc12,13.For hydroelectric concrete , the design requirements have some characteristics, such as long design age, low design strength, low hydration temperature rise, and low temperature gradient14. All these requirements agree with t

10、he characteristics of LHC. Furthermore, LHC has a high hydration activity at later ages, the effect of which can improve the inner micro-crack. Based on above-mentioned analyses, the properties of low-heat Portland cement concrete were studied in detail in this paper. Compared with the moderate-heat

11、 Portland cement (MHC) concrete, the anti-crack behavior of LHC concrete was analyzed.2 ExperimentalMHC was produced in Gezhouba Holding Company Cement Plant, China; and LHC was produced in Hunan Shimen Special Cement Co. Ltd., China. The chemical compositions and mineral compositions of cement are

12、listed in Table 1 and Table 2 respectively, and the physical and mechanical properties of cement are listed in Table 3.In spite of a little difference in chemical compositions, there is an obvious dissimilarity between the mineral component of LHC and that of MHC because of the different burning sch

13、edule. The C3S (Alite) content of MHC is higher than that of LHC, and the C2S (Belite) content of LHC is higher than that of MHC. Alite is formed at temperatures of about 1 450 , while Belite is formed at around 1 200 . Therefore, LHC can be manufactured at lower kiln temperatures than MHC. And the

14、amount of energy theoretically required to manufacture LHC is lower than that of MHC.Belite hydrates comparatively slowly, and the early compressive strengths of pastes, mortars, and concretes containing LHC are generally lower as a result. The long-term strength and durability of concrete made from

15、 LHC can potentially exceed those of MHC. The results from Table 3 show that the early strength of LHC pastes is lower than that of MHC pastes, and that the strength growth rate of LHC is higher than that of MHC.The hydration heat of bonding materials was tested. Class I fly ash of bonding materials

16、 came from Shandong Zhouxian Power Plant, China. The experimental results shown in Table 4 indicate that the hydration heat of LHC is much lower than that of MHC. The 1-day, 3-day and 7-day hydration heat of LHC without fly ash is 143 kJ/kg, 205 kJ/kg, 227 kJ/kg, respectively. The 1-day, 3-day and 7

17、-day hydration heat of MHC without fly ash is 179 kJ/kg, 239 kJ/kg, 278 kJ/kg, respectively. Compared with MHC, the average hydration heat of LHC concrete is reduced by about 17.5%. Obviously, low hydration is of advantage to abate the pressure to temperature control, and to reduce the crack probabi

18、lity due to the temperature gradients. The adiabatic temperature of LHC concrete and MHC concrete was tested. As a result, the adiabatic temperature rise of LHC concrete is lower than that of MHC concrete and the different value ranges from 2 to 3 in general.After adding fly ash, all specimens show

19、a lower hydration heat, and it decreases with increasing fly ash content. For MHC with 30% fly ash, the 1 d, 3 d, 7d accumulative hydration heat is reduced by 14.5%, 20.5%, 21.9%, respectively; and for LHC with 30% fly ash, the 1 d, 3 d, 7 d accumulative hydration heat is reduced by 21.7%, 26.3%, 23

20、.3%, respectively. Obviously, the effect of fly ash on the hydration heat of LHC is more than that of MHC. It is well known that the fly ash activation could be activated by Ca(OH)2. LHC has a lower content of C3S and a higher content of C2S than MHC, so the Ca(OH)2, namely the exciter content in hy

21、dration products of LHC pastes is lower. Decreasing the hydration activation of fly ash reduces the hydration heat of bonding materials.3 Results and DiscussionIn this experiment, ZB-1A type retarding superplasticizer and DH9 air-entraining agent were used. The dosage of ZB-1 was 0.7% by the weight

22、of the blending, and the dosage of DH9 was adjusted to give an air-containing of 4.5% to 6.0%. The parameters that affected the dosage included the composition and the fineness of the cement used, and whether the fly ash was used. Four gradations of aggregate were used, 120 mm-80 mm: 80 mm-40 mm: 40

23、 mm-20 mm: 20 mm-5 mm=30:30:20:20.The term water-to-cementitious was used instead of water-to-cement, and the water-to-cementitious ratio was maintained at 0.50 for all the blending. The slump of concrete was maintained at about 40 mm, and the air content was maintained at about 5.0% in the experime

24、ntal. After being demoulded, all the specimens were in a standard curing chamber. The mix proportion parameter of concrete is listed in Table 5.3.1 Physical and mechanical propertiesThe physical and mechanical properties include strength, elastic modulus, limits tension, and so on. The results of st

25、rength shown in Table 6 indicate the early strength (7 d curing ages) of LHC (odd samples) concrete increases slowly. The ratio between 7 d compressive strength and 28 d compressive strength of LHC concrete is about 0.4, while for MHC concrete the ratio is about 0.6. Compared with MHC concrete, the

26、growth rate of strength of LHC concrete becomes faster after 7 d curing ages. The compressive strength for 28 d, 90 d, 180 d curing ages of LHC concrete containing 20% of fly ash is 30.2 MPa, 43.8 MPa, 48.5 MPa, respectively, while that of MHC concrete containing 20% of fly ash is 28.3 MPa, 35.6 MPa

27、, 39.8 MPa, respectively. The content of C2S in LHC is higher than that in MHC, which results in the above-mentioned difference.Table 6 shows that the strength growth rate of concrete made with fly ash blended cements is higher than that of blank specimens; the more the dosage of fly ash, the higher

28、 the growth rate. Fly ash has a glassy nature, which can react with Ca(OH)2. Since Ca(OH)2 is a hydration product of cement, the reaction between fly ash and Ca(OH)2, called “secondary hydration”, will happen at latish ages. The magnitude of Ca(OH)2 is affected by some factors, such as the water-to-

29、cementitious, the dosage of cement.The elastic modulus and the limits tension of concrete are given in Table 7. Under same mixing proportion, the elastic modulus of LHC concrete is approximately equal to that of MHC; the 28-day limits tension of LHC concrete is increased by 1010-6 to 15 10-6 than th

30、at of MHC, and the 90-day limits tension of LHC concrete is increased by 1210-6 than that of MHC concrete. The above results show that the use of LHC improves the limits tension of concrete. Increasing the limits tension of concrete will be benefit to the crack resistance of concrete.3.2 Deformation

31、 characteristicsDeformation characteristics of concrete include drying shrinkage, autogenous deformation, creep, etc. The drying shrinkage of concrete is shown in Fig.1. The drying shrinkage increases with age. At early ages a up to 90 days, all the LHC concrete specimens show a lower drying shrinka

32、ge; and it decreases with increasing the fly ash content. When containing 30% of fly ash, the drying shrinkage of LHC concrete is 363 10-6 at 90 days, while for MHC concrete the value is 40810-6. As a result, the volume stability of LHC concrete is better than that of MHC concrete in drying environm

33、ent.Experiment results of autogenous deformation of concrete are given in Fig.2. There is an obvious difference between the development of autogenous deformation of LHC concrete and that of MHC concrete. The autogenous deformation of LHC concrete has an expansive tendency. At early ages up to 14 day

34、s, the autogenous deformation of pure LHC samples increases with age, and the 14-day value reaches a peak of 2010-6. The autogenous deformation of pure LHC samples decreases with age at 14 days to 90 days, and the 90-day value is 1010-6. After adding 30% of fly ash, the autogenous deformation of LHC

35、 concrete increases with age, and the 90-day value is 6110-6. The autogenous deformation of MHC concrete has a tendency to shrink, especially without fly ash.3.3. DurabilityThe durability of concrete is evaluated by antipenetrability grade and frost-resistant level. Under the pressure of 1.2 MPa, th

36、e permeability height of pure LHC samples is 3.1 cm, while that of pure MHC samples is 2.0 cm. The test data indicate that the LHC concrete has an excellent performance in anti-penetrability, as well as MHC concrete. The permeability of concrete increases somewhat with addition of fly ash. At the en

37、d of the 250 freezing and thawing cycling, there is a little difference in both mass and resonant frequency. Both LHC concrete and MHC concrete show an excellent frost-resistant behavior. The results of this work confirm that LHC concrete systems have an adequate anti-penetrability and frost-resista

38、nce to adapting design requirement.3.4 Analysis of crack resistanceIn order to control the crack phenomena, it is important to accurately evaluate the anti-crack behavior.As well known, concrete is a kind of typical brittle materials, and its brittleness is associated with the anti-crack behavior15.

39、 The brittleness is measured by the ratio of tension strength to compressive strength. With the increase of the ratio, concrete has a less brittleness, better crack resistance and toughness. It is indicated from the experiment results shown in Table 6 that the ratio of LHC concrete at all stages of

40、hydration is higher than that of MHC concrete, which shows that LHC concrete has a better anti-crack behavior.In the crack control and design of hydroelectric mass concrete, the original evaluation of crack resistance behavior of concrete is using the utmost tensile strength which is shown in the fo

41、llowing expression of Eq.1.=PE (1)where, P is the limits tension of concrete, and E is the elastic modulus of tension, which is assumed to be equal to the elastic modulus of compression16.It is indicated from the calculation results shown in Table 8 that the utmost tensile strength of LHC concrete a

42、t all stages of hydration is higher than that of MHC cncrete.The research on materials crack resistance which is the basis for esign, construction and the choice of raw materials, has been popular in todays world. Through a great deal of research, it is widely thought that concrete with a better cra

43、ck resistance has a higher tension strength and limits tension, lower elastic odulus and adiabatic temperature rise and better volume stability17,18.Based on above-mentioned results, the LHC concrete has a higher tension strength and limits tension, lower elastic modulus and adiabatic temperature ri

44、se, and lower drying shrinkage than MHC concrete. Compared with MHC concrete, the autogenous deformation of LHC concrete has an expansive tendency. Although the early strength of LHC concrete is lower than that of MHC concrete, its later strength has approached to or even exceed that of MHC concrete

45、.4 Conclusionsa) The early compressive strength (7 d curing ages) of LHC is lower, but its later strength (28 d, 90 d curing ages) has approached to or even exceed that of MHC.b) Compared with MHC, the average hydration heat of LHC concrete is reduced by about 17.5%.c) Under the same mixing proporti

46、on, the elastic modulus of LHC concrete is approximately equal to that of MHC, and the limits tension of LHC concrete is increased by 1010-6-1510-6 than that of MHC.d) The drying shrinkage of LHC concrete is obviously smaller than that of MHC concrete, and the autogenous deformation of LHC concrete

47、has a tendency to expand.e ) The LHC concrete has a better anti-penetrability and frost resistance, as well as the MHC concrete.f) At all stages of hydration, the anti-crack strength of LHC concrete is higher than that of MHC concrete, and the former has a higher ratio of tension strength to compres

48、sive strength. References1 C X Yu, Z Kong. Research on the Causes of Cracks in Mass Concrete and Control Measures J. Low Temperature Architecture Technology (China), 2005 (5): 112-1132 A A Almusallam, M Maslehuddin. Effect of Mix Proportions on Plastic Shrinkage Cracking of Concrete in Hot Environme

49、ntsJ.Construction and Building Materials, 1998 (12): 353-3583 Xu Jingan, An Zhiwen. Countermeasure of Temperature Crack of Mass ConcreteJ. Journal of Hebie Institute of Architectural Engineering, 2005,23 (3):36-404 Peng Weibing, Ren Aizhu. Effects and Evaluation on Cracking of Concrete Incorporating

50、 Supplementary Cementitious MaterialsJ. Concrete (China), 2005 (6): 50-645 Xiao Reimin, Zhang Xiong. Effect of Binder on Drying Shrinkage of Concrete J.China Concrete and Cement Products, 2002 (5): 11-136 Ye Qing, Chen Xin. Research on the Expansive Mechanism of Moderate Heat Portland Cement with Sl

51、ight Expansion J.Journal of the Chinese Ceramic Society, 2000, 128 (4):335-3477 Shi Xun. Application of Slight Expansion Cement on Concrete of Stage II Works of the Three Gorges Project J. Cement (China). 2002 (5): 12-148 Nagaokas, Mizukosui M. Property of Concrete Using Beliterich Cement and Ternar

52、y Blended Cement J. Journal of the Society of Materials Science, Japan, 1994, 43 (491): 488-4929 Ge Juncai. Technology Progress of Cement and Concrete M. Beijing: China Building Material Industry Press , 1993:275-27610 Metha P K. Investigation on Energy-saving CementJ. World Cement Technology, 1980,

53、 1(3): 166-17711 Taylor. Cement ChemistryM. London: Academic Press, 1990:142-15212 Sui Tongba, Liu Kezhong. A Study on Properties of High Belite Cement J. Journal of the Chinese Ceramic Society, 1999, 127 (4): 488-49213 Yang Nanru, Zhong Baixi. Study on Active -C2SC. Symposium on Cement,1983:180-185

54、14 Yang Huanquan, Li Wenwei. Research and Application of Hydroelectric ConcreteM. Beijing, China Water Power Press,2004:393-39415 E Ringot, A Bascoul. About the Analysis of Micro-cracking in ConcreteJ. Cement and Concrete Composites, 2001 (23):261-26616 Li Guangwei. Assessment for Anti-Crack Perform

55、ance of Concrete J. Advances in Science and Technology of Water Resources (China), 2001, 21 (2): 33-3617 Liu Shuhua, Fang Kunhe. Summarization of Norm of Crack Resistance of ConcreteJ. Highway (China), 2004 (4): eJ 105-107低热硅酸盐水泥混凝土的抗裂性能摘 要：低热硅酸盐水泥混凝土 （LHC）的特性详细地被研究。实验的结果表示 LHC 混凝土有比较高实际的机械行为、形变和耐久性

56、的特性。与中热硅酸盐水泥 （MHC）相较, LHC 混凝土的平均水合作用热被减少大约 17.5%.在相同的混台比例比率之下， LHC 混凝土的断热温升减少了 2 -3，而且 LHC 混凝土的限度张力比 MHC 增加了 10 10-6-15 10-6 。而且，它表明 LHC 混凝土比 MHC 有更好的反裂痕行为。关键词: 低热硅酸盐水泥; 大体积混凝土; 高抗裂; 中热硅酸盐水泥1、介绍调查在大体积混凝土的裂纹是一个热门问题，已将注意了很长一段时间。混凝土的裂痕有多的因数造成的，但是他们主要地由大众的混凝土中的热的位移所引起1-3。因此在大众的混凝土上的主要的技术是该如何减少热的位移而且提高混凝

57、土的反裂痕能力。众所周知，粘结材料的水化作用热是造成大众混凝土外部和的内部之间温差的主要原因4,5。为了要减低水化作用混凝土的内部温度，一些方法已经在混合比例比率设计方案中被提出。这些包括使用中热硅酸盐水泥(MHC)，减少水泥的用量，增加普通硅酸盐水泥(OPC)，MHC有好处例如低水化热，长期强度的高增长率6，7。因此在大众混凝土使用中用MHC更合理。低热硅酸盐水泥 （LHC）, 即高硅水泥现在正在吸引全世界很多人的兴趣。这主要是由于它在制造过程中比传统的硅酸盐水泥消耗较低的能量和排放更少的CO2。LHC 有许多引人注目的特性，像是水合作用是放热少、优良耐久性，及其他，因此持续更高深的研究是很

58、重要的8-10 。C2S 的长期强度能接近或者超过C3S的长期强度11 。此外，C2S有一系列的特征优于C3S。这些包括更少的游离CaO，低水化热，良好的韧性，坚固的水化产物，良好的防化学腐蚀性，良好的安定性，等等12-13。因为水化混凝土，设计需要有一些特性，像是长设计材龄，低设计强度、低水合作用温升和低的温度梯度14。这些需要符合LHC 的特性。此外， LHC在后期有一个高水合作用，水化作用能改良材料内部微裂纹。综上所述，低热硅酸盐水泥混凝土的特性在文中详细地研究。与中硅酸盐水泥（MHC）混凝土相比，LHC混凝土的反裂痕行为被分析了。2 实验MHC 在中国葛洲坝股份公司水泥厂生产； LHC

59、 在中国湖南石门特殊水泥公司生产。水泥的化学成分和矿物合成在表1和表2 分别地列出来，水泥的物质和机械，虽然化学成分差别不大，但在不同的燃烧条件下MHC 和LHC 的矿物组成却明显不同。MHC的C3S（Alite）含量比LHC高，但是LHC的C2S（Belite）含量比 MHC 高。Alite 在温度大约1450形成, 当 Belite 在 1200左右时形成. 因此， LHC能在比MHC更低的窑炉温度下被烧成。而且理论上LHC烧成时比MHC节省更多的能量。Belite水化反应时放热相对比较慢，所以导致含有 LHC 的浆体、耐火水泥和混凝土的早期抗压强度通常比较低。以LHC为原料的混凝土的长期

60、强度和耐久性可能超过MHC。表 3 的结果显示LHC浆体的早期强度比MHC低，但是LHC 的强度增长率比MHC高。会黏结材料的水合作用热测试。第一阶段黏结材料的粉煤灰来自中国山东周县发电厂。表 4显示的实验的结果表明LHC 的水合作用热比MHC低很多。没有粉煤灰的LHC的1天、3天和7天的水合作用热分别是 143 kJ/kg、205 kJkg，227 kJkg。没有粉煤灰的MHC的1天、3天和7天的水合作用热分别是179 kJ/kg、239 kJkg，278 kJkg。LHC 混凝土的平均水合作用热比MHC减少了大约 17.5%.显然地，低的水合作用对温度控制降低压力有利，降低由于温度梯度引起

61、的裂纹。LHC混凝土和MHC混凝土的绝热温度测试。结果， LHC 混凝土的绝热温升比 MHC 混凝土低2 -3 。在添加粉煤灰之后，所有试样都表有一个更低的水合作用热，而且它随着粉煤灰含量减少而增加。对于MHC用30%粉煤灰，1天、3天，7 天总的水合作用热分别减少了14.5%、20.5%、21.9%；而对于LHC用30%的粉煤灰1天、3天、7天总的水合作用热分别减少 了21.7% 、26.3%、23.3%。明显，粉煤灰的影响在LHC的水化热多过MHC。众所周知， Ca（OH）2 能激活粉煤灰的活性。LHC比MHC有更少的C3S更多的C2S，因此 Ca（OH）2, 即 LHC浆体的在水合作用的

62、产物激发物含量下降。随着粉煤灰的水合作用活化的减少减少黏结材料的水合作用热也随之减少。3、结果与讨论在这实验中，用ZB-1 A型态妨碍超塑性和DH9外加剂。ZB-1 的药量是混合的重量的 0.7% ，而且 DH9 的药量被调整呆了外加剂的 4.5%-6.0%。不管粉煤灰是否被用，影响了药量的参数的事的水泥合成物和水泥细度。凝聚体的四个阶度是120毫米80毫米：80毫米40毫米：40毫米20毫米：20毫米5毫米30:30:20:20。在水类水泥代替用了水水泥期间，水类水泥在所有的混合物中的比率维持在 0.50。在试验中，混凝土的大裂纹被控制在大约 40 毫米之内，空气含量被控制在大约 5.0%。

63、在被脱模后，所有样本放在一个标准养护室中养护。混凝土的混合比例比率参数在表 5 被列出来了。3.1 物理力学性能物理力学性能包含强度、硬度、屈服强度等等。表 6显示LHC（单数的样本）的早期强度（7 d 强度）是缓慢增长的。LHC混凝土的7 d抗压强度和28d抗压强度之间的比例大约 0.4 ，而MHC混凝土的比例大约是0.6。与 MHC混凝土相比较， LHC混凝土强度的增长率在7 d之后增长得更快。含20%粉煤灰的LHC混凝土在28 d 、 90 d、180 d后的抗压强度分别是30.2 MPa、43.8 MPa、48.5 MPa，含20%粉煤灰的MHC混凝土在28 d 、 90 d、180

64、d后的抗压强度分别是28.3 MPa、35.6 MPa、39.8MPa。造成上述差异的原因是LHC的C2S含量比MHC高。表6表示与参入粉煤灰的水泥的强度增长率比不加的的高；粉煤灰的添加量愈多，增长率也愈高。粉煤灰有玻璃的性质，可以与Ca（OH）2反应。因为Ca（OH）2是水泥的水水化产物，粉煤灰和Ca（OH）2 之间的反应,被称为“第二水化反应”，将在迟些时候发生。Ca（OH）2的多少被一些因数影响，比如水浆体，水泥的添加量。在表7中给模量和屈服极限。在相同的混合比例下， LHC 混凝土的弹性模量和 MHC大约相等；LHC 混凝土的 28 天的屈服极限比MHC增长了1010-6-1510-6

65、，而LHC混凝土的90天的屈服极限超过了MHC 混凝土1210-6。上述的结果表明LHC 的使用改良了混凝土的屈服极限。增加混凝土的屈服极限将会有利于混凝土的裂痕的出现。3.2 形变特征混凝土的形变特性含干燥收缩、自生的形变、潜动等等。Fig.1显示了混凝土的干燥收缩。干燥收缩是随时间增加的。 在刚到90天时，所有的 LHC 混凝土试样表示一个低的干燥收缩； 而且它随着粉煤灰的增加而降低。当粉煤灰的含量为30%是，LHC混凝土在90天的干燥收缩为36310-6 ，而为MHC混凝土数值是40810-6。结果， LHC 混凝土的安定性在干燥环境中比 MHC 混凝土好。Fig.2指出了混凝土的自生形变的实验结果。MHC混凝土和LHC混凝土的自生形变的发展有明显不同。LHC混凝土的自生形变有膨胀的趋向。在刚到14天之前，纯LHC 样本的自生形变随时间增长，14天时达到最大2010-6。纯LHC样本在 14天至90天之间自生形变开始降低