土木外文翻译--通过再碱化技术增加钢筋混凝土的使用.doc

毕业设计(论文)外文资料翻译系： 机械工程系 专 业： 土木工程 姓 名： 学 号： (用外文写)外文出处： Universidad Nacional de San J-uan Av.General San Martin Oeste附 件： 1.外文资料翻译译文；2.外文原文。指导教师评语： 签名： 2011年 3月18日注：请将该封面与附件装订成册。中文3053字附件1：外文资料翻译译文通过再碱化技术增加钢筋混凝土的使用摘要：钢筋混凝土是一种经过适当的准备处理措施之后就能够具有很强的稳定性,不受外部因素条件和内部因素条件恶化的经济型材料。混凝土保护由于性质活泼而易受腐蚀的钢筋。当有效的保护氧化膜为钢筋构件的工作提供良好的工作条件时，混凝土就能够很有效的保护钢筋免受腐蚀的作用。这种依附在钢筋表面的保护膜使钢筋产生一种性质稳定的钝化层，从而限制金属的氧化。 这种使钢筋钝化而产生的保护膜由于高浓度的氯化物，具体的碳酸盐化合物，高混凝土孔隙率等因素作用下，可以被部分的或者完全的破坏，因此原本是看作为一个腐蚀过程。 在库约地区，主要是阿根廷的圣胡安省和门多萨省，具有许多有山洞和/或含有丰富的硝石露头粉的地区，正是高盐度的地理环境特点，改变了这里建筑结构的耐久性。结构状况的恶化开始于微小的裂缝和裂纹，由于裂纹和裂缝而暴露在潮湿空气之中的钢筋与环境因素积极氧化反应从而造成建筑结构的快速腐蚀，而因为钢筋腐蚀产生的额外费用却没有包括在建设项目之中。本项研究和学习是将再碱化技术的工作应用于一个位于农业生产地区的学校建筑。这些建筑的结构受腐蚀问题的影响十分严重。电化学技术由于混凝土表面碱性电解质的结合，允许硅酸盐水泥混凝土中的孔隙水的pH值的增加从而使埋入在混凝土中的钢筋钝化，这个再保护的过程避免钢筋混凝土继续腐蚀，并且延长了建筑结构的使用寿命。 这项研究的技术可以应用到钢筋混凝土结构的碳化问题上。关键词：钢筋混凝土 - 腐蚀 再碱化1、 引言一个钢筋混凝土建筑结构的完整性主要取决于它的结构组成部分的质量和用量。通过这种方式使建筑结构获得最佳的使用性能，以保证延长它的使用寿命。混凝土主要是从以下两个方面来保护钢筋免受腐蚀的影响：a）混凝土在钢筋和周围氧化坏境之间形成一个物理隔离屏障使钢筋免受腐蚀；b）因为混凝土中的孔隙水具有较高的pH值，在水泥的水化反应中产成了一种化合物使钢筋钝化得到一层保护膜，就是这样产生的化学保护防止钢筋被腐蚀。 根据环境选择的合理等级的混凝土，低的混凝土孔隙率，钢筋和混凝土之间的充分粘结，钢筋混凝土的最低裂缝和剥落，以及钢表面钝化膜变化的稳定性等因素有助于提高钢筋混凝土结构的耐久性。然而，任然有几种原因可以使这种钝化膜发生破坏。在实践操作中，一些因素有可能导致钢筋混凝土发生在电化学领域内的碳酸腐蚀。此外，氯化物或其他前面已经一起提到过的如混凝土开裂，高的混凝土孔隙率以及可能达到饱和的混凝土毛孔，都可以让氧气，二氧化碳和氯离子发生迁移。当然它们都需要湿度和环境侵蚀的条件，来完成钢筋混凝土的腐蚀过程。 一旦钢筋混凝土发生损害性的腐蚀，我们可以观察到三种不同的斜坡，Cyted（1997）：a）对钢筋而言，腐蚀作用表现在降低了钢筋原来的直径和它的机械能力；b)对混凝土而言，腐蚀作用表现在它所产生膨胀氧化物在钢-混凝土的接触面造成裂缝和剥落，c）同理在钢-混凝土依附处的地方。 在广大的库约地区，主要是在阿根廷的圣胡安省和门多萨省，存在着广泛的已被水侵蚀过和/或含有丰富的硝石露头粉的地区，这些地区创造了结构恶化的理想条件。这里是一个有着严寒的冬天以及极端温度突变的高风险地震带地区。所有因为先前所列举的因素产生的费用都是可以避免的；因为如果钢筋混凝土出现剥落和开裂的现象，那么建筑物就应当修理，这就意味着巨大的资金需求。 为了延长建筑结构的使用寿命，加强诸如阴极保护、环氧覆盖等等各种不同科学技术在钢筋混凝土中的应用对于我们来说是十分有必要的。 这篇研究论文详细阐述了一种通过提供间接混凝土保护的非传统的再碱化技术，这种通过增加混凝土孔隙水的pH值、混凝土多孔的解决方案，在混凝土表面合成了一种碱性电解质。它具有阻止或者减轻混凝土钢筋锈蚀的优势。 这也是一个用来修复已被碳化损坏的结构非常合适的方法程序。 这种方法已经在进行了测试，测试不仅仅局限于实验室水平，也将在学校建筑的建造中加以运用。 多亏了以前的研究工作数据库(Solorza苏达权等,2003),使得我们可以在阿根廷-圣湖安省Albardn部选择一个以面积为样本的几个学校建筑示范区。然而,在上述技术中只有一个被选为修理应用。对不同的建筑进行了初步及详细的检查（Feli等，1989）。得到的诊断结果表明了这些建筑物的已经达到的损害程度。据估计，这是为了恢复两年周期的而强制进行的。2、方法论即使是高质量的混凝土也可能因为碳化而导致发生腐蚀的问题。如一个非常薄的覆盖和使用存在二氧化碳可能进入的裂缝的混凝土。在这种条件下，即使是在较短的时间内，位于裂缝中的钢筋也会被腐蚀。混凝土保护层的边缘由于碳化而容易腐蚀。这是因为边和角处很高含量的二氧化碳往往会扩散到钢筋造成腐蚀。如果钢筋没有能够得到足够的覆盖，碳化将导致腐蚀并且钢筋很快就会分裂。再碱化技术的试管测试1 - 应用人工老化技术（Rodriguez等人，1993年）。2 - 对混凝土碳化的酚酞测试，Sturm y S.H. Kosmatka (1991).3 - 测试腐蚀检测，使用半电池电位测量按美国ASTM C - 876。4 - 再减化技术。5 - 测试酚酞指示剂。再碱化技术用于真正的圆柱1 - 对混凝土碳化的酚酞试验的测定。2 - 测试的半电池电位测量腐蚀检测按照美国ASTM C - 876。3 - 再碱化技术。4 - 测试酚酞指示剂。3、结果和讨论为了进行第一次测试，6根管子被连续3年埋在研究部位。碳化实验取得的结果表明，碳化面平均在边处有5mm,在角处有10mm。这幅图片描绘了后，酚酞测试应用后的棱柱试管。图为酚酞测试已经得到了应用后的测试管。这些试管对应的电势值已经被记录下来，分别为-100毫伏和-250毫伏。这些电势值从一个定性的角度来讲表明了它们受腐蚀的可能性非常低。如果把这些数据铭记在头脑里,一个快速老化技术就应用于试管测试中。必须按照以下的尺寸来设置圆柱管的尺寸：直径：300毫米，长400毫米，结构必须经过公尺的验证：4根12铁棒和两根300毫米的 6等距金属箍线；覆盖层的厚度：20毫米；用于拌合的干燥的混凝土：66.65（沙2 / 5，石头3 / 5）；普通混凝土：22.25；水分：11.1；设置：将试管完全浸没放置28天；混凝土的密度：2.19克/立方厘米和设定房间的温度，因为它们类似于被修复的圆柱，以此取代棱镜分析的试管。便得出了圆柱管的电势值，以遵循老化过程的影响。相应的平均值列入表1。 表1：腐蚀测试管的电势值时间（月） 2 4 6 8 10 11腐蚀电位增高（毫伏） - 298 - 375 - 462 - 512 - 560 - 620根据记录的电势值以及试管呈现出的变为赭色并且带有轻微的纵向裂缝的物理状态，我们可以估计得出试管的腐蚀性的到增强。我们必须注意到为了执行再碱化技术；阳极进行了重新的设计和阐述。阳极是一个采用AISI 316，1.25钢丝在两层纱布和纤维素纤维纸浆之间形成的一个网格。当前使用的测试电源输出是1安培/40 伏。选定的电解液解决方案是一种氢氧化锂溶液。截至到目前还有没有足够的测试值，以确定该项技术的所有优点。它显示了再碱化方法中的一种钢筋混凝土圆柱试管的简化方案。4、部分结论一般的情况下，被用于检查的学校建筑是来自被认为相当于没有人居住的条件的环境状态。学校建筑采样的铁柱是含有由诸如硫酸盐，氯化物和混凝土碳化等，以及由此产生的负面影响而造成严重锈蚀的结构元素。由于当地的排水系统没有能适合适应该地区排水的要求，因此使它具有很高的潜水位水平，这对于建立起新的系统以达到尽量减少潜水位水层的波动，从而避免盐的浓度集中是十分方便的。应用人工试管老化加速技术，使得我们有可能在学习中模拟出于与真实状态下的钢筋混凝土实际样本相近的条件。非常重要需要强调的是，通过达到在实验室水平应用再碱化技术，可以模拟出建筑物的实际状况，目的是为了在真实的实际工作情况时可以改进技术的实施和得到更好的结果。附件2：外文原文（复印件）INCREASE REINFORCED CONCRETE STRUCTURESUSEFUL, BY REALKALIZATION.Abstract. Reinforced concrete is an economical material that appropriately prepared has much stability against, external or internal deterioration. Concrete protects steel bars, which are susceptible to corrosion due to their high energy. Concrete protection is effective when a protective oxide film is formed in proper working conditions. This film adheres to the steel surface creating a stable passive layer and restricting the metal solution.The passive film on the reinforcing steel can be partially or totally destroyed due to its exposition high concentrations of chloride, a concrete carbonate, high porosity of concrete, etc., originating as consequence a corrosion process.The Cuyo area, mainly San Juan and Mendoza provinces of Argentina, has many cave in areas and/or abundant saltpeter outcrop powder, that characterizes high salinity environment, modifying the structures durability built.Deterioration begins with micro fissures and cracks that expose steel to environment aggressiveness causing a quick corrosion, and generating expenses which were not included in the construction project.This work researches realkalization and the study technique is applied to a school building located in an agricultural area. Such building structures are seriously affected by corrosion problems.The electrochemical technique allows a pH increase of concrete pores, due to the incorporation of a surface alkaline electrolyte. This process reprotects reinforced concrete avoiding corrosion continue on and increasing the useful life of the structure.The technique under study can be applied to reinforced concrete structures with carbonation problems.Keywords: Reinforced Concrete Corrosion Realkalization1. Introduction.The integrity of a reinforced concrete structure depends on the quality of its components and of its dosage, as well. In this way it acquires the best properties in order to guarantee a service life extension. Concrete protects steel in two ways: a) it constitutes a physical barrier separating steel from the surroundings and b) as it has a high pH value, it forms chemical compounds during cement hydrate reactions creating a passive film on steel, which produces a chemical protection against corrosion.Factors such as, an appropriate concrete against environment, low concrete porosity, adequate steel-concrete adherence, minimum cracking and spalling and, the possibility of reforming a stable passive film oxides on steel contribute to increase the durability of reinforced concrete structures.However, there are several causes that can produce the destruction of such passive film. In practice, some factors may cause reinforced concrete electrochemical corrosion within the carbonated area. Besides, the presence of chlorides or of all of the other already mentioned together with cracking and high concrete porosity,and the probable saturation of concrete pores, which allow the O2, CO2 and Cl- migration. All of them need humidity and the environmental aggressors, as well, to complete the corrosion process.Once the corrosion occurs damages can be observed in three different slopes, Cyted (1997): a) on steel, which diminishes its original diameter and its mechanical capacity; b) on concrete, since it generates expansive oxides in the steel-concrete interface causing fissures and spalling and c) in steel-concrete adherence.In Great Cuyo Region, mainly in San Juan and Mendoza provinces - Argentina, there exist wide areas which have been invaded by water return and/or abundant saltpetre outcrop powder, creating the ideal conditions for structures deterioration. It is a high risk seismic zone, with frosty winters, and abrupt temperature variations. All of the costs derived from the previously enumerated factors are avoidable; since if spalling and cracking occur,buildings should be repaired and, it implies great demands of money.In order to extend the structure service life, it is necessary to use reinforced concrete applying diverse techniques such as cathodic protection, epoxy cover, among others.This research paper deals with a non-conventional realkalization technique, which offers an indirect protection through concrete. It would allow increasing the pH concrete aqueous porous solution, incorporating an alkaline electrolyte from concrete surface. It has the advantage of stopping or lessening the concrete reinforcement corrosion.It is also a very appropriate procedure to repair structures which have been damaged by carbonation.This process was tested, not only at laboratory level, but it will be also practically applied to a school building.Thanks to a previous research work data base (Solorza et al., 2003), it was possible to select an area as a sample of several school buildings in Albardn Department - San Juan Province-Argentina. Nevertheless, only one was chosen to be repaired applying the above mentioned technique. Preliminary and detailed inspections (Feli et al., 1989) were carried on different buildings.The diagnosis obtained showed the degree of damage underwent by those buildings. It was estimated that is peremptory to restore it in a two-years-period.2. Methodology.Carbonation may also cause corrosion problems even in high quality concrete. If a very thin cover is used and there are cracks in concrete, CO2 may enter. Under these conditions, in a short period of time, the steel located in the crack area will corrode.The concrete cover edge may easily corrode due to carbonation. Edges and corners have a high content of CO2 which tends to diffuse to the steel reinforcement. If steel fails to have the adequate cover, carbonation will cause corrosion and will soon splinter.Realkalization technique steps on test tubes.1- Application of the artificial aging technique (Rodrguez et al., 1993).2- Determination of the presence of concrete carbonation by phenolphthalein test, Sturm y S.H. Kosmatka (1991).3- Testing for corrosion detection, using Half-Cell Potential Measurements according to ASTM C-876.4- Realkalization technique.5- Testing by phenolphthalein test.Realkalization technique steps on the real columns.1- Determination of the presence of concrete carbonation by phenolphthalein test.2- Testing for corrosion detection by Half-Cell Potential Measurements according to ASTM C-876.3- Realkalization technique.4- Testing by phenolphthalein test.3. Results and Discussion.To carry on the first test, six tubes were buried in the areas under study for 3 years. The carbonation test achieved showed that the carbonation fronts have a mean percentage of 5 mm in edges and 10 mm in corners.The photo depicts a prismatic test tube after the application of the phenolphthalein test.The photo shows a test tube to which the phenolphthalein test has been applied.The potential values of tubes -100 and - 250 mV were registered. Those values indicate a very low corrosion probability from the qualitative point view. Bearing these data in mind, a quick aging technique was applied to test tubes. It was necessary to build cylindrical tubes with the following dimensions: diameter: 300 mm, length 400 mm; the structure was verified with a pacometre: 4 iron bars, 12 and two 300 mm spacedstirrup wire of 6; cover thickness: 20 mm; composition of arid concrete: 66.65% (sand 2/5, stone 3/5); common concrete: 22.25%, water: 11.1 %; setting: 28 days with completely submerged test tubes; concrete density: 2.19 g/cm3 and room temperature to replace the prismatic test tubes, since they were similar to the columns to be repaired. Potential measurements of the cylindrical tubes were carried out, so as to follow the aging process effect. The corresponding mean values are included in Table 1.Table 1: Potential test tubes corrosiontime (months) 2 4 6 8 10 11Ecorr (mV) - 298 - 375 - 462 - 512 - 560 - 620According to the registered values and the test tubes physical states which became ochre with longitudinal fissures, it was estimated that the test tubes reinforcement was corroded.It is necessary to remark that to perform the realkalization technique; an anode was redesigned and elaborated. The anode with an AISI 316, 1.25 steel wire forming a mesh located between two layers made of gauze and cellulose fibre pulp. The tension and current source: 1A /40 V. The selected electrolyte is a LiOH solution. Up-to-date there are no enough test values to determine all the advantages of this technique. It shows a simplified scheme of the realkalization process a reinforced concrete cylindrical test tube.4. Partial conclusions.In general, the inspected school buildings were from fairly accepted to uninhabited conditions state.The school sampled has structural elements with severe corrosion in its iron columns resulting from negative contents such as, sulphates, chlorides and concrete carbonation, as well.As the drainage system fails to be appropriate for the area, since it has very high phreatic levels, it will be convenient to build new system to minimize the fluctuations of the phreatic layer, so as to avoid salts concentrations.Applying the artificial