阴极保护—氯盐污染海工混凝土的最佳长效维修解决方案

混凝土结构劣化问题如今已成为建筑业面临的最严重的问题和巨大的挑战之一。在过去的30年里,对于遭受氯盐污染的混凝土码头结构,通常采用传统的＂打补丁＂法维修,即移除爆裂的混凝土,然后用维修砂浆回填。但是对于这些维修过的结构来说,难以得到长期的维修效果。通常在维修后短短几年内,维修过的部位周围又重新需要维修。阴极保护是一种电化学技术,利用直流电流来中止混凝土中钢筋的腐蚀进程。阴极保护方法已经被证明为氯盐污染的结构的最有效、技术上可行的长效修复解决方案。本文将重点介绍钢筋混凝土结构劣化的原因以及修复这些结构的最新方法。     

RTM成型技术在码头钢筋混凝土结构修复中的应用

采用树脂传递模塑工艺Resin Transfer Molding(RTM)对上海石化热电总厂煤码头钢筋混凝土结构进行填充修复和防腐蚀处理。分析了钢筋混凝土材料的腐蚀以及RTM成型工艺的关键因素:钢筋混凝土的失效主要是由于Cl-渗入混凝土内部而导致钢筋材料发生电化学腐蚀,而树脂料对增强材料浸润能力以及铺设技术对RTM成型工艺都有直接的影响。通过RTM成型对受损码头进行填充修复,明显提高了结构承载和改善其外观。     

钢筋混凝土结构的电化学处理及其研究进展

钢筋混凝土结构的电化学处理技术能有效抑制混凝土碳化和氯化物侵入这两个主要因素引起的混凝土中钢筋的腐蚀,对已经发生去钝化的钢筋具有良好的修复作用,是一种高效率的钢筋混凝土结构修复技术,具有广阔的应用前景.本文论述了该技术的基本原理、处理效果、影响因素及副作用,并提出了评价和建议.     

侯保荣院士接受《科学时报》采访

"在世界能源、资源日趋紧缺的今天,我们应高度重视混凝土构筑物的腐蚀问题,及时有效、科学合理地为混凝土构筑物进行防护及修复,确保钢筋混凝土构筑物高安全运营、长寿命服役.这对资源节约和社会可持续发展具有重要意义."中国工程院院士侯保荣在接受(科学时报》采访时指出,近年我国频繁发生的建筑损毁事故,既说明钢筋混凝土腐蚀的严重性,也表明钢筋混凝土结构防护修复技术有着巨大的市场前景.     

海港码头钢筋混凝土的腐蚀和防护技术

海港码头钢筋混凝土结构的腐蚀破坏是相当迅速的,往往不到10年就普遍出现顺筋锈胀开裂、剥落,并日益加剧,严重威胁钢筋混凝土结构的耐久性,它造成的直接、间接损失之大,远远超出人们的意料。本文就海洋环境下钢筋混凝土结构的腐蚀和防护技术进行综述,并提出了海洋环境下各腐蚀区域钢筋混凝土结构的防腐蚀措施。     

海工钢筋混凝土的腐蚀与防护

海水具有很强的腐蚀性。如果不采取防护措施，海工钢筋混凝土结构会受到严重腐蚀。本文结合当前现有研究成果，对海洋环境下钢筋混凝土结构的腐蚀特征和防护技术进行了论述。     

输变电系统中钢筋混凝土结构的劣化及其危害

输变电系统设施中有大量的钢筋混凝土结构,服役环境的长期作用使钢筋混凝土结构的组分发生变化,其性能也逐渐劣化,给电网的安全运行带来隐患。结合输变电系统设施中钢筋混凝土结构典型的劣化案例综述了其劣化现象及可能产生的危害,为电网输变电系统的运行维护提供支持。     

水环境腐蚀与混凝土的耐久性

我国钢筋混凝土结构面临着广泛的水腐蚀环境,包括江、河、湖、海水,地下水、雨水等。特别是海水、受污染的淡水和酸雨,会对钢筋混凝土结构造成明显的腐蚀破坏,是影响混凝土耐久性的重要因素。本文探讨相关问题,并就一些技术因素和对应策略进行讨论。     

浅谈钢筋混凝土结构的腐蚀及预防

钢筋混凝土结构的耐久性和可靠性是建筑工程重要的质量指标,而腐蚀是对其产生影响的重要因素。在实际的工程建筑的过程中,钢筋混凝土很容易发生腐蚀作用,进而导致建筑的质量存在一定的问题。接下来,本文将结合钢筋混凝土产生腐蚀的机理以及原因,探讨预防钢筋混凝土腐蚀的方法以及措施。     

钢筋腐蚀引起混凝土结构破坏的修补对策

混凝土中钢筋腐蚀是影响钢筋混凝土结构耐久性的主要问题之一.修补措施要耗费大量资财,因而迫切需要改善新建结构的耐久性,同时保证己有结构修补和加固后的耐久性.但是,修补钢筋腐蚀引起的结构破坏很少有标准和指南,因此,制订这种标准是当务之急,它应该是以这种破坏的关键过程的现有全部知识为依据,区别不同情况,正确地规定有效的修补对策.     

Numerical evaluation of the capacity of galvanic anode systems for patch repair of reinforced concrete structures

Cathodic protection (CP) is an electrochemical repair or corrosion prevention technique for steel structures exposed to a corrosive environment. For reinforced concrete (RC) usually impressed current CP is used, due to the comparably high resistivity of the concrete, serving as electrolyte. Nevertheless, the market provides a wide range of galvanic anode systems for RC structures. Their most common use is the application within the framework of partial concrete replacement due to chloride-induced corrosion. This patch repair is often accompanied by the so-called anode ring effect, causing accelerated corrosion of the rebar in the substrate concrete in the vicinity of repair patches. This is caused by the cathodic capabilities of the repassivated rebar. Galvanic anodes are reported to prevent this effect. In this paper, a numerical model is proposed, which is capable of determining the effectiveness of the method dependent on, for example, the type and quantity of anodes, rebar content, and geometry or climatic conditions. The method is presented for a specific set of input parameters and the applicability is discussed against the background of different protection criteria.     

Baupraktische Erfahrungen bei der Instandsetzung chloridbelasteter Parkhäuser aus Stahlbeton. Schadensdiagnose,Instandsetzungsmaßnahmen,Erfahrungen

Experiences in practice in the repair of concrete structures for car park constructions damaged by chloride induced corrosion Investigations, possibilities of repair, experiences at several constructions In chloride contaminated steel reinforced concrete structures there are several parameters which determine the risk of corrosion and the intensity of a chloride induced corrosion of the reinforcing steel. The content of chloride in the concrete is the most important parameter. Caused by the methods of repair and caused by the different situations of constructions it is unavoidable that areas with high concentrations of chloride may remain in the repaired steel reinforced concrete structures. Up to now there are no long term experiences available to give an answer to the question how different methods of repair have been sucessful in practice. Therefore we will report upon our experiences in different methods of repair in case of chloride induced corrosion of steel reinforced concrete car park structures. The repaired structures reported have been successful over a period of eight to fifteen years in practice. These car park structures are actually in use without any harm or restrictions.     

Sensitivity Analysis of Corrosion Rate Prediction Models Utilized for Reinforced Concrete Affected by Chloride

Chloride-induced reinforcement corrosion is one of the major causes of premature deterioration in reinforced concrete (RC) structures. Given the high maintenance and replacement costs, accurate modeling of RC deterioration is indispensable for ensuring the optimal allocation of limited economic resources. Since corrosion rate is one of the major factors influencing the rate of deterioration, many predictive models exist. However, because the existing models use very different sets of input parameters, the choice of model for RC deterioration is made difficult. Although the factors affecting corrosion rate are frequently reported in the literature, there is no published quantitative study on the sensitivity of predicted corrosion rate to the various input parameters. This paper presents the results of the sensitivity analysis of the input parameters for nine selected corrosion rate prediction models. Three different methods of analysis are used to determine and compare the sensitivity of corrosion rate to various input parameters: (i) univariate regression analysis, (ii) multivariate regression analysis, and (iii) sensitivity index. The results from the analysis have quantitatively verified that the corrosion rate of steel reinforcement bars in RC structures is highly sensitive to corrosion duration time, concrete resistivity, and concrete chloride content. These important findings establish that future empirical models for predicting corrosion rate of RC should carefully consider and incorporate these input parameters.     

Embedded sensor system to detect chloride permeation in concrete: an overview

Exposure of concrete structures to chloride-bearing solutions such as sea water or de-icing salts brine can affect their durability to stand against deterioration caused by corrosion of steel reinforcement. In order to monitor the chloride ingress into concrete, embedded chloride sensors can be used in concrete structures. Through the sensors, they monitor the initiation of corrosion of steel reinforcement with time, and measure the open circuit potential and polarisation of steel reinforcement, humidity inside the concrete, chloride content and many more. This paper provides an overview of the latest development of chloride permeation measurement in concrete by evaluating the current techniques being used in industry and highlighting a new approach to monitor chloride ion progress in concrete structures wirelessly.     

Reinforced concrete structures – shall concrete remain the dominating means of corrosion prevention?

The acknowledged serious deterioration of reinforced concrete structures due to chloride induced corrosion has been the main fuel for research and development of very dense and impermeable concrete, so‐called high performance concrete (HPC). This development has dominated concrete research up through the 80'ies and 90'ies. The results have technically been successful. However, the practical use of such concretes on site have often posed serious difficulties, resulting in at times very low performance concrete structures although HPC was specified. The discrepancy between concrete quality reached in the laboratory, what is being specified in the design and what can realistically be achieved on site is seldom in balance. Alternative means of more or less reliable means of corrosion prevention, often based on organic materials, have during recent years been developed to protect our inorganic concrete and reinforcement. However, a highly reliable means of corrosion prevention has been the introduction of stainless steel reinforcement, which is available with dimensions and strengths directly interchangeable with ordinary carbon steel reinforcement. It has been proven that stainless steel and carbon steel can be in metallic contact when cast into concrete, without causing galvanic corrosion. This seems, for the present, to be like an unexpectedly simple and highly reliable solution to the corrosion problems. As exemplified, this technology is rapidly gaining momentum in highly corrosive environments – and concretes being much more robust to execution can now take over from HPC.     

Modified hydrotalcites as a new emerging class of smart additive of reinforced concrete for anticorrosion applications: A literature review

Modified hydrotalcites (MTHs) represent a group of technologically promising materials for addition to concrete to improve its durability in aggressive environment, owing to their low cost, relative simplicity of preparation, and plenty of unique composition variables that may be adopted. Up to date, a lot of academic work and commercial interest on MHTs have been invested, but relatively few studies focus on cementitious materials, particularly in exploiting their potential applications in corrosion protection of reinforced concrete structures. In this article, the mechanism of corrosion in reinforced concrete and concrete properties that affect corrosion of reinforcement are briefly introduced. In addition, the existing knowledge with regard to synthesis and characterisation methods of MHTs, ion exchange within the MHT structure as well as the application of MHTs in the cementitious materials were reviewed accordingly. As a new emerging class of smart additive of reinforced concrete, MHTs are expected to contribute to the effort of searching for effective measures to improve the durability of reinforced concrete.     

Newly developed acrylate injection resin gels for structural sealing and active corrosion protection of embedded steel reinforcement

The corrosion potential of waterproofing acrylate injection resins is relevant when these materials are used in reinforced concrete structures. Sika Technology AG has developed a new generation of acrylate resin gels for use as injection material to seal cracks, repair honeycombed areas, and fill voids in concrete structures. This new material shows promising results in electrochemical laboratory tests for the provision of corrosion protection to the embedded reinforcement. These electrochemical analyses have been carried out at Sika Technology AG and in the Institute for Building Research (ibac) at RWTH Aachen University. The results of this investigation and the corresponding conclusions for their use in building, construction, and refurbishment works are presented below.     

环氧涂层钢筋及其应用

钢筋的腐蚀，尤其当有氯离子存在时，是混凝土结构腐蚀破坏的主要原因。在防止钢筋腐蚀的各种措施中，采用涂层既简便又有效。熔融结合环氧粉末涂层的综合防护性能优良，已经大量应用于钢质管道和钢管桩，也很适合于钢筋的保护。钢筋表面涂装环氧涂层可用静电喷涂方法，工艺基本成熟。环氧涂层钢筋的研究开发在美国始于20世纪的70年代，主要应用于撒布化冰盐的路桥和各类海工结构。我国在1997年就制订了环氧树脂涂层钢筋的行业标准。目前，国内已能生产环氧涂层钢筋，并开始实际应用。随着我国国民经济的发展，越来越多的工程要求使用环氧涂层钢筋，市场前景肯定十分广阔。