文献翻译微生物引起的劣化混凝土-检讨

1、Microbiologically induced deterioration of concrete - A ReviewAbstractMicrobiologically induced deterioration (MID) causes corrosion of concrete by producing acids (including organic and inorganic acids) that degrade concrete components and thus compromise the integrity of sewer pipelines and other

2、structures, creating significant problems worldwide. Understanding of the fundamental corrosion process and the causal agents will help us develop an appropriate strategy to minimize the costs in repairs. This review presents how microorganisms induce the deterioration of concrete, including the org

3、anisms involved and their colonization and succession on concrete, the microbial deterioration mechanism, the approaches of studying MID and safeguards against concrete. In addition, the uninvestigated research area of MID is also proposed.Keywords: microbial deterioration, concrete corrosion,

4、biogenic sulfuric acid1、IntroductionThe life-cycle of concrete architectures should consider all factors that might cause a structural system to perform unacceptably at any point during its lifetime. This includes extreme events (e.g., earthquakes, cyclones) or the progressive and sustained loss of

5、capacity caused by operational or environmental factors. In general terms, deterioration can be defined as a loss of structural capacity with time as a result of the action of external agents or material weakening. It has many dimensions and depends on the type of structure, the constitutive materia

6、l, the environmental conditions and the operation characteristics, as well as other factors. Progressive deterioration has perhaps the broadest impact on the long-term performance of infrastructure systems and the largest potential economic consequences. It has been observed that the loss of structu

7、ral capacity with time is caused mainly by chloride ingress, which usually leads to steel corrosion (loss of effective cross-section of steel), concrete cracking, loss of bond (aggregate-hydrated cement paste). Among these causes of structural degradation, it has been noted that deterioration arisin

8、g from biological sources is significant in harsh environments. Nevertheless, the role of biologically-induced degradation with respect to reinforced concrete structures remains uninvestigated. has been defined in the literature as: “any undesirable change in the properties of a material caused by t

9、he vital activities of organisms”; and “the process by which “biological agents (i.e., live organisms) are the cause of the structural lowering in quality or value”. is usually referred to as microbiologically induced deterioration (MID).of concrete structures is caused by organisms that grow in env

10、ironments on concrete surfaces that offer favorable conditions (e.g., available water, low pH etc.). Conducive environments may have elevated relative humidity (i.e., between 60% and 98%), long cycles of humidification and drying, freezing and defrosting, high carbon dioxide concentrations (e.g., ca

11、rbonation in urban atmospheres), high concentrations of chloride ions or other salts (e.g., marine environments) or high concentrations of sulfates and small amounts of acids (e.g., sewer pipes or residual water treatment plants).Considerable researches has examined of concrete structures by living

12、organisms, including underground structures, sewage systems, at-sea structures and wastewater treatment systems. The costly effect of MID on various structural systems is often underestimated since the microorganisms often accelerate processes that would occur in their absence at slower rates. It ha

13、s been estimated that -related structural problems cost billions of dollars a year in infrastructure maintenance and repair.Dynamics of the MID of Concrete StructuresOrganisms play a significant role in the deterioration of concreteRecent experimental developments have provided a better understandin

14、g as to how biological and physicochemical processes associated with MID affects the long-term durability and mechanical properties of concrete structures. Deterioration of concrete is often found in structures exposed to aggressive environments, such as environments promoting sulfate attack or chlo

15、ride ion penetration. Although concrete mix proportions are commonly designed to comply with acceptable design life requirements, poor quality control, improper characterization, unanticipated changes in the environmental conditions or exposure to aggressive environments can produce premature deteri

16、oration and reduce the load carrying capacity. The most common and widely studied cause of progressive deterioration in concrete structures is chloride ingress. It has been reported that biological processes can accelerate this deterioration process by severely modifying the physicochemical properti

17、es of the reinforced concrete. Although little attention has been given to, some studies have shown that live-organisms may play a significant role in the deterioration of concrete structures. This could be particularly important in marine structures such as ports and offshore platforms and is repor

18、tedly more common in structures such as sewage systems and waste water treatment plants.There are enough evidences to show that a wide variety of organisms can cause concrete deterioration. The action of microorganisms on concrete structures can be classified according to their effects on concrete s

19、urfaces, concrete matrices, and on cracking and crack growth. According to , the action of microorganisms affect the concrete mainly by contributing to the erosion of the exposed concrete surface, reducing the protective cover depth, increasing concrete porosity, and increasing the transport of

20、 degrading materials into the concrete that can accelerate cracking, , and other damage and reduce the service life of the structure.Microbial colonization on concreteAfter construction, concrete is usually immune to biological attack because of its high alkalinity. Little microbial activity occurs

21、at such a high pH. This high pH is the result of the formation of calcium hydroxide i.e.Ca(OH)2, as a byproduct of the hydration of cement. Usually, the erosive action of water and/or the friction of structural elements with other materials generate roughness on the concrete surface. This condi

22、tion, in addition to the availability of moisture and nutrients, facilitates the colonization of microbes on concrete surfaces. However, the colonization of sulfur-reducing and sulfur-oxidizing bacteria on concrete has always been associated with the sulfur cycle in their environment, especially in

23、aquatic environments. Sulfate is distributed in the aquatic and marine environments world wide. The anaerobic sulfur-reducing bacteria can convert sulfate into sulfide, which in turn combines with hydrogen to form hydrogen sulfide. Over time, the pH of the alkaline concrete surface is gradually redu

24、ced by the carbonation and neutralization of hydrogen sulfide that builds up in various systems. Subsequently, the volatile hydrogen sulfide is subject to oxidation into sulfuric acid by sulfur-oxidizing bacteria.When the pH is lowered towards neutral, a lower pH on the concrete surface creates cond

25、itions for further microbial colonization by and/or acidophilic organisms. Typically, sp. sp., including  play key roles in these colonization events. When microorganisms settle on a concrete surface, they form a, which is followed by the chemical of concrete. According to  of concrete is

26、mainly caused by bacteria, fungi, algae and lichens.Microbial colonization on concreteMicrobial growth further reduces the surface pH of concrete, thereby leading to significant biogenic release of and sulfuric acid. Once the pH of the surface of the concrete drops below 9 in the presence of suffici

27、ent nutrients, moisture and oxygen present, some species of sulfur bacteria like  sp. can attach to the concrete surface and reproduce. T. was found to be the first bacteria to colonize new concrete pipe surfaces, disappearing gradually as deterioration became more severe. As the pH c

28、ontinues to fall to moderate or weakly acidophilic conditions,  establish on the surface of concrete. At pH levels below 5, T. starts to grow and produces high amounts of sulfuric acid, and the pH drops to as low as 1.5. When the pH reaches 3, T. grows vigorously. The low pH favo

29、rs the formation of elemental sulfur, and T. rapidly oxidizes it directly to sulfate ion. The pH continues to decline to about 1.0, at this point it becomes inhibitory even for T. The climax community will be dominated by T. and the acidophilic capable of utilizing orga

30、nic waste products excreted by T. This succession no doubt differs in its details in specific cases. for example, emphasized T. in studies in Australia. found no T. in their studies in Germany.微生物引起的劣化混凝土-检讨微生物引起的劣化（中）所产生的酸导致腐蚀混凝土（包括有机和无机酸），降低混凝土构件而妥协的排水管道等结构的完整性，造

31、成了重大的世界性问题。的基本腐蚀过程的理解和因果剂将有助于我们开发降低维修成本的适当策略。本文综述了微生物是如何导致混凝土劣化，包括所涉及的生物和他们的殖民统治和演替对混凝土的劣化机理，微生物，研究中针对混凝土微生物腐蚀的方法。此外，研究中还提出了研究区。关键词：微生物劣化，混凝土腐蚀，生物硫酸1、 简介混凝土结构的寿命周期应考虑所有的因素，可能导致结构系统进行不可接受的在任何时候。这包括极端事件（例如，地震，龙卷风）或渐进和持续的操作或环境因素引起的容量损失。总的来说，恶化可以被定义为一个结构承载力随时间的流失而导致的行为的外部代理或材料弱化（桑切斯席尔瓦，2008）。它有许多尺寸取决于结构

32、类型，构材料，环境条件和运行特点，以及其他因素。逐步恶化，也许有广泛影响的基础设施系统的长期性能和最大的潜在的经济后果。它已被观察到的结构的能力随时间的损失主要是由氯离子引起的，这通常会导致钢的腐蚀（钢材有效截面损失），混凝土开裂，亏损的债券（骨料水泥净浆）和剥落（巴斯蒂达斯等人，2008）。这些结构退化的原因中，人们已经注意到，从生物源中产生的恶化在恶劣的环境中是有意义的。然而，生物降解作用引起的钢筋混凝土结构方面仍然未被调查。腐蚀已在文献中定义的：“任何不受欢迎的变化在一种材料的性能造成重要的活动；和“有机体”的过程，“生物制剂（即，活的生物体）是引起结构降低质量或价值”（玫瑰，1981）

33、。生物降解通常被称为微生物引起的腐蚀（中）。混凝土结构的腐蚀是由微生物生长在混凝土表面，提供有利的条件（例如环境引起的，可用的水，低pH值等）。有利于环境可能有相对湿度升高（即，之间的60%和98%），长周期的增湿和干燥，冷冻和解冻，高二氧化碳浓度（例如，碳化城市大气中），高浓度的氯离子或其他盐类（例如，海洋环境）或高浓度的硫酸盐和少量的酸（例如，下水道或残留的水处理厂）。大量的研究已经研究了混凝土结构的腐蚀是由活的生物体，包括地下工程，污水处理系统，在海洋结构物和废水处理系统（戴维斯等人，1998；岛民等人。，1991；冈部等，2007；等人，2000；维克等人，2001）。中对不同结构体系

34、的昂贵的效果往往低估了由于微生物通常会以较慢的速率加速发生在他们缺席的情况下处理。据估计，生物降解相关的结构性问题，耗资数十亿美元的基础设施的维护和保修一年（桑切斯席尔瓦，2008）。2、对混凝土结构中的动力学生物在混凝土劣化中发挥着重要的作用最近的实验的发展提供了一个更好地了解如何生物和物理化学过程与中长期影响混凝土结构耐久性与力学性能。混凝土的劣化是经常暴露在恶劣的环境中发现的结构，如环境促进硫酸盐和氯离子渗透。虽然混凝土配合比通常的设计符合可接受的设计寿命要求，质量差，不当的表征，在环境条件下或暴露于恶劣环境下的意想不到的变化可以产生过早恶化和降低承载能力。在混凝土结构中的进行性恶化的最

35、常见和最广泛研究的原因是氯离子侵蚀。据报道（桑切斯席尔瓦，2008），生物过程的严重改变钢筋混凝土加速劣化过程的物理化学性质。虽然被腐蚀的关注很少，一些研究（巴斯蒂达斯等，2008；等人，2003）已经表明，活的生物可能在混凝土结构的恶化中发挥重要的作用。这可能是特别重要的海洋结构，如港口和海上平台和据称是更常见的结构如排污系统和污水处理厂（首席人事官和森，1995）。有足够的证据表明，各种各样的生物会导致混凝土劣化（表1）。对混凝土结构的微生物作用可根据混凝土表面，影响混凝土的矩阵的分类，并对开裂和裂纹增长。根据桑切斯席尔瓦（2008），微生物作用的影响混凝土的主要贡献的暴露的混凝土表面的侵

36、蚀，降低防护罩的深度，增加混凝土的孔隙率，提高降解材料运输到混凝土，可以加速开裂，剥落，和其他损伤，降低结构使用寿命。具体微生物在具体建设，生物免疫攻击的高碱度。在这样的小微生物活性高。高pH钙羟基如Ca（OH）2，水合水泥。侵蚀，摩擦水和/或其他材料与结构元素的具体产生的粗糙表面（里巴斯-席尔瓦，1995）。不管一个人多，还原硫氧化细菌和硫的具体美联社在线has一直与他们环境中硫的循环，在水生环境（佐藤耶尔马兹等人，2009年，2010年）。硫酸是在水生和海洋环境的分布式的万维网。硫还原菌在厌氧硫酸盐硫化物可以转换为氢，在转弯氢硫化物。过碱性pH值时，混凝土表面和精简模式中和氢硫化物，在各种builds跟踪系统马托斯和尼尔森等人，1995年；2005年，张等人，2008）。茶挥发性硫化物，氢氧化是受一酸含硫氧化细菌模式。pH值为中性，在较低的pH值条件的混凝土表面上继续创源模式和/或微生物嗜酸。氧化亚铁硫杆菌。排硫杆菌包括诺发系统，中间球海胆和氧化硫硫杆菌）的关键作用，这些事件在播放（帕克，1947）。当在线解决混凝土表面，他们在生物膜的形态（多明戈等人，2011），化工学院具体的生物破坏。根据-等