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1.
钢筋混凝土失效检测及其耐久性研究进展 总被引：5，自引：0，他引：5
在探讨了导致钢筋混凝土失效的主要原因基上,主要 综述了混凝土结构破坏以及钢筋失效的检测及提高钢筋混凝土耐久性的方法,并简要介绍了 钢筋混凝土研究未来的主要发展趋势. 相似文献
2.
混凝土中钢筋锈蚀的电化学阻抗谱特征研究 总被引：3，自引：0，他引：3
关于混凝土钢筋锈蚀等效电路模型中各元件的物理意义理解不尽相同.为了对模型元件的物理意义给出合理解释,设计了由氯盐侵蚀和混凝土碳化导致钢筋锈蚀的两种加速试验.通过对钢筋锈蚀试块阻抗谱特征的分析研究,对模型元件的物理意义给出了合理解释.研究发现,氯盐锈蚀试块具有三段容抗弧,即三个时间常数;而碳化锈蚀试块阻抗谱与钝化钢筋试块... 相似文献
3.
M. R. Geiker 《工业材料与腐蚀》2012,63(12):1114-1118
The design and execution of reinforced concrete structures shall together with planned maintenance lead to the intended level of safety and serviceability during the entire service life of the structure. The possible impact of execution on the performance of the finished concrete structure is not always recognized; e.g., is pre‐testing of alternative mixes often undertaken at laboratory conditions. Mix design should include an assessment of the stability and property development of the concrete at the anticipated execution conditions as well as an evaluation of the robustness of the concrete to natural variations in mix composition and execution. Through selected examples the paper addresses the importance of execution for obtaining the designed performance and durability of reinforced concrete structures. 相似文献
4.
A strong interest for the durability of reinforced concrete structures currently exists in industry and research [1]. Against the background of immense costs for maintaining reinforced concrete structures and repairing damage caused by corroding reinforcement steel, this interest lead to a German joint research project. The aim of this network‐based (www.bam.de/dfg537.htm) research group is, to deliver the basic knowledge of the corrosion propagation and to make a probabilistic tool available for engineers so that a complete design for durability, concerning reinforcement corrosion, will be possible. 相似文献
5.
With the implementation of the repair method “increasing the electrical resistivity by coating” (MR 8.3), no direct repassivation of the reinforcing steel is initially intended. The success of the repair is rather linked to the change of the corrosion-relevant parameters over time. These include an increase in the concrete resistivity due to dehydration and gradual decrease in corrosion currents and driving voltages on the reinforcing steel. Within the scope of a research project funded by the German Research Foundation (DFG), application limits for the repair principle W-Cl could be defined. The chloride content present in the concrete at the rebar is the significant limiting factor for the application. While the corrosion activity even with moderately dehydrated specimens under diffusion-retarding coatings at chloride contents of 1 wt% Cl−/c is in the range of the passive current density, this cannot be generally determined for chloride contents of 2 wt% Cl−/c. The type of coating has a decisive influence on the dehydration of the concrete. For example, less dense concretes under a permeable coating (acrylic dispersion/OS 4) can dry out to such an extent that the passive current density is reached. With semipermeable coatings and the presence of high chloride contents of 2 wt% Cl−/c, the repair principle W-Cl does not lead to success according to the available test results. 相似文献
6.
The repair method 8.3 “Corrosion protection by increasing the electrical resistance” according to EN 1504 (or the repair principle W-Cl according to the DAfStb directive “Protection and repair of concrete building materials”) represents a technically and economically interesting method for the repair of chloride-contaminated concrete components. The coating applied as part of the repair principle prevents further water absorption of the concrete and, due to its permeability to water vapor, allows the concrete to dehydrate. Over time, this leads to an increase in the electrolytic resistance and thus to a reduction in the rate of corrosion. The article deals with the basic principles underlying this repair principle, deals with the current regulatory situation, and shows the responsibility of the expert planner. Groundbreaking studies on the effectiveness of the repair principle were carried out by Prof. Raupach, to whom this article is dedicated, and are summarized in this paper. The objective of the new studies, which build on the aforementioned research, is to establish universally accepted application limits, for example, the level of the remaining chloride concentration, for the low-risk use of this repair method. 相似文献
7.
The feasibility of using 2304 duplex stainless steel rebar in seawater concrete was determined by studying the passivation and corrosion behavior of steel in solutions simulated curing and service stage of concrete, respectively. The results demonstrate that 2304 duplex stainless steel rebar could be used with seawater concrete because of a stable passive film formed on the steel surface during the curing stage of concrete even in the presence of 2 M chloride ions. However, due to the synergistic effect of concrete carbonation, the rebar suffered a corrosive attack by chloride due to the lack of OH? inhibition. 相似文献
8.
As part of the macro cell corrosion process of reinforcement steel, the resistivity of concrete plays a crucial role. In order to investigate the influence parameters on the resistivity of concrete, the results of a discrete quantification were presented and implemented into a factorial approach for modelling corrosion propagation. First results delivered significant deviations from values obtained by measuring. Using Gauss' method of least mean squares provided a decrease in deviations. The hereby obtained deviations were lower than the scatter of the measuring results. A usability of the proposed factorial approach could therefore be approved. 相似文献
9.
U. M. Angst R. D. Hooton J. Marchand C. L. Page R. J. Flatt B. Elsener C. Gehlen J. Gulikers 《工业材料与腐蚀》2012,63(12):1047-1051
This paper sums up the International RILEM Workshop on Present and Future Durability Challenges for Reinforced Concrete Structures, held at ETH Zurich in Switzerland on 17–18 April 2012. Major focus is put on the discussions. During the latter it was revealed that one of the key durability challenges lies in predicting the performance of new materials, where the increasing diversity of cement and concrete plays a major role. As most current engineering models are not capable of predicting actual field performance adequately, a knowledge‐based approach to durability will become more important than ever. Only a scientific approach on a multi‐scale and interdisciplinary level will allow predicting the performance of new materials (where no long‐term experience is available for fitting purposes). This will facilitate the use of more performance‐based durability design that is urgently needed to promote innovative, long‐lasting solutions. 相似文献
10.
Probabilistic approaches are available for service life design of reinforced concrete structures subjected to reinforcement corrosion. The International Federation for Structural Concrete (fib) has proposed a model code where design equations and related parameters, involving materials properties, exposure conditions and construction details, are reported. This paper investigates the role of design parameters in the prediction of service life by applying the fib design procedure to existing structures suffering carbonation‐induced corrosion. Results of the modelling were compared to results of the inspection and a significant difference was observed. In order to investigate the reasons for this difference, the roles of concrete cover thickness and carbonation depth were considered separately in the modelling of service life. The concrete cover thickness had a significant effect on the output of the service life modelling, which however was not sufficient to explain the discrepancy between in situ and modelling results. The modelled values of carbonation depth were also affected by errors; sensitivity analysis showed that, although some parameters had higher influence than others, no single parameter had a predominant role. 相似文献
11.
本文研究了醇胺类化合物对混凝土钢筋的阻锈作用。利用静态失重法、极化曲线等方法,在与传统缓蚀剂亚硝酸钠对照的基础上,检测和评价乙二醇和乙醇胺两种醇胺类有机缓蚀剂,对钢筋在含有NaCl的模拟混凝土孔溶液中的电化学腐蚀行为及其阻锈作用。极化曲线图表明模拟混凝土孔溶液pH=11．5和加入缓蚀剂浓度为3％（与孔溶液的体积比）时,醇胺类缓蚀剂对钢筋阻锈效果最好,钝化电位为940mV;静态失重法表明缓蚀剂为水泥重量的3％是防止混凝土钢筋发生点蚀最适宜的浓度,此时缓蚀率达94％;实验同时发现在以上条件下乙醇胺的缓蚀作用与亚硝酸钠相当,且乙醇胺与其它缓蚀剂有良好协同效应,能明显增强其对钢筋的阻锈能力。 相似文献
12.
钢筋混凝土养护过程中的电化学行为 总被引：5，自引：0，他引：5
利用电化学交流阻抗法对钢筋混凝土养护期间的电化学行为进行了研究.探讨了添加氯离子引起点蚀与未添加氯离子、钝化状态的钢筋混凝土的电化学差异.并对实验结果进行拟合,提出了针对两种体系的等效电路模型,解释了钢筋在混凝土介质中的腐蚀行为 相似文献
13.
14.
Since the beginning of the 20th century, in Italy as in many other countries, reinforced concrete (RC) became one of the most popular construction materials and it was used for buildings, monuments, infrastructures, etc. Several of these structures, although of recent formation, have now been included in the cultural heritage, because of their architectural or social relevance. As a consequence of the typical urban or rural exposure conditions of these buildings, they often suffer damage due to carbonation‐induced corrosion of reinforcement, such as concrete spalling or cracking or rust stains that may affect the serviceability of structures. Furthermore, chloride‐induced corrosion of reinforcement, may also concern buildings exposed to de‐icing salts or marine environments. Due to strict requirements related to the preservation of the original materials and texture, the repair of structures that belong to the cultural heritage cannot rely on the conventional repair technique, based on the replacement of carbonated concrete. Therefore, the conservation of RC buildings of the cultural heritage is a challenge, since it requires the development of specific strategies aimed at finding the best compromise between, on one hand, the restoration of structural safety and the prevention of future damage and, on the other hand, the preservation of the original materials and surfaces. This paper analyses the results of inspections carried out on several buildings, built in Italy throughout the 20th century in different micro‐ and macro‐climates, with the aim of showing their peculiarities with regard to steel corrosion and the selection of restorations strategies. 相似文献
15.
为获取更为真实的钢筋锈蚀动力学参数,运用电化学频率调制技术对混凝土中锈蚀钢筋进行了测试;通过与单向极化三点法测试结果对比,明确了电化学频率调制技术的测试参数;结果表明,混凝土中锈蚀钢筋B a范围在65~250 mV/dec,大于溶液中的30~120 mV/dec;对EFM测试得到的极化电阻R P和腐蚀电流I corr进行曲线拟合分析,得到两者之间经验关系,修正了线性极化法B值。 相似文献
16.
The quantification of active corrosion rate of steel in concrete structures through nondestructive methods is a crucial task for scheduling maintenance/repair operations and for achieving accurate service life predictions. Measuring the polarization resistance of corroding systems and using the Stern‐Geary equation to calculate the corrosion current density of active steel is a widely‐used method for this purpose. However, these measurements are greatly influenced by environmental factors; therefore, accurate monitoring of corrosion requires integrating the instantaneous corrosion rates over time. Although advanced numerical models are helpful in research settings, they remain to be computationally expensive and complex to be adopted by general engineering community. In this paper, a practical numerical model for predicting corrosion rate of uniformly depassivated steel in concrete is developed. The model is built on Stern's earlier work that an optimum anode‐to‐cathode ratio exists for which the corrosion current on the metal surface reaches a maximum value. The developed model, which represents the corrosion rate as a function of concrete resistivity and oxygen concentration, is validated using experimental data obtained from the literature. 相似文献
17.
Corrosion of reinforced concrete structures occurs in two stages characterized by different intensities of the corrosion development: the initiation period of the corrosion process and the propagation period of the corrosion process. Consequences of the reinforcement corrosion in concrete are the reduction of the cross‐sectional area of the reinforcement bars, and cracking of the concrete cover. The reduction of the reinforcement structural capacity due to the corrosion, over a sufficiently long period of time, may result in structural failure of the designed structural element. It is impossible to quantitatively express all corrosion factors influencing loss of the reinforcement structural capacity. Their influences on the structural design could be considered through a factor of safety applicable to the corrosion limit state. Factor of safety is calculated considering fuzzy sets theory and qualitative inputs of various influencing factors. 相似文献
18.
K. Reichling M. Raupach J. Broomfield J. Gulikers V. L'Hostis S. Kessler K. Osterminski I. Pepenar U. Schneck G. Sergi G. Taché 《工业材料与腐蚀》2013,64(2):116-127
For reinforced concrete structures a localisation of all significant critical areas can only be done by a full surface inspection. The economic advantages are obvious: uncritical areas have not to be repaired expensively 1 . The first step of the assessment should always be a visual inspection 2 . The range of deterioration causes can be limited and the degree of deterioration may be estimated roughly. The inspection program can be adjusted to the requirements. By means of a full surface potential mapping areas with a high risk for chloride induced reinforcement corrosion can be localised, although no deteriorations are visually detectable at the concrete surface. In combination with concrete cover depth and resistivity measurements areas with corrosion promoting exposure conditions can be localised even if the reinforcement is not yet depassivated. The following publication gives an overview about the essential full surface investigation methods to localise critical areas regarding corrosion of steel in concrete. The selection of methods is based on the inspection procedure given in 2 . 相似文献
19.
用丝束电极研究混凝土中钢筋腐蚀的不均匀性 总被引：6，自引：0，他引：6
用8×8阵列丝束电极模拟研究了混凝土中钢筋的腐蚀.将混凝土试样浸泡在10 %NaCl溶液中,通过测量铁丝束电极的自腐蚀电位和极化电阻,获得了在相同埋置深度和不同埋置深度时,铁丝腐蚀的电位、极化电阻和腐蚀速度分布等信息,研究了混凝土结构和氯离子浓度对它们的影响.结果表明,混凝土中铁丝腐蚀不均匀.自腐蚀电位和极化电阻较分散,电位随时间负移、极化电阻变小,丝束之间的电位差增大.随铁丝埋入深度增加,电位负移量、氯离子浓度和腐蚀速度都减小、极化电阻增加 相似文献
20.
A study has been conducted on the chloride-induced corrosion behavior of 304L and 316LN stainless steel clad reinforcing bars (rebar) in concrete and in synthetic concrete pore solution. Metallographic examination of the as-received clad bars confirmed a strong metallurgical bond at the core/clad interface and some grain growth interdiffusion of species at the interface. Both bars showed a wide variation in coating thickness around the rebar circumference, from a minimum of 0.32 and 0.60 mm to a maximum of 1.4 and 2.8 mm in the 304L clad and 316LN clad, respectively. The electrochemical results and visual examination after autopsy showed that active corrosion was yet initiated on either the solid and clad stainless steel or carbon steel rebar in the sound noncracked concrete specimens. In contrast, corrosion had initiated in the bars embedded in cracked concrete at the base of the crack and extended along or around the bars. In the concrete and synthetic pore solution tests, the current densities of both solid and clad stainless steel rebar exposed to ∼21% chloride brine solution for days between 400 and 1,500 were similar. This was also the case for current densities of the straight and bent stainless steel bars tested in the synthetic pore solution test. 相似文献