混凝土结构用钢筋耐蚀性提升研究进展

介绍了混凝土结构中钢筋腐蚀行为及耐蚀周期,综述了耐蚀合金化、表面耐蚀改性等钢筋耐蚀性提升方法的机理、应用与研究进展,以期为混凝土结构用钢筋耐蚀性提升的后续研究与应用提供参考。     

低合金耐蚀钢筋锈蚀研究现状及存在的问题分析

评述了近年来国内外有关低合金耐蚀钢筋锈蚀问题研究发展状况,从钝化行为、腐蚀行为角度综述了耐蚀钢筋耐蚀性评估研究成果,归纳了耐蚀钢筋可能存在的耐蚀机理,从腐蚀诱发、腐蚀扩展角度综述了耐蚀钢筋混凝土结构服役寿命预测研究结果,指出了耐蚀钢筋混凝土结构服役寿命预测模型研究自身特征及可循理论基础。分析了耐蚀钢筋耐蚀性评估及其混凝土结构寿命预测研究所存在的问题,并对耐蚀钢筋锈蚀研究发展趋势和前景提出了展望。     

Cr对耐蚀钢筋在混凝土模拟液中耐蚀机理的影响

研究了Cr对低合金耐蚀钢筋在饱和Ca(OH)_2混凝土模拟液中耐蚀性能的影响机制,为低合金耐蚀钢筋的研发提供理论上的依据。周期浸润腐蚀及循环动电位极化等实验表明,含Cr耐蚀钢筋的腐蚀敏感性及腐蚀速率远低于HRB400钢筋,其耐蚀机理主要表现为:Cr的添加改变了耐蚀钢筋的显微组织,形成大量细小且均匀分布的粒状贝氏体;Cr的添加改变了钢筋表面钝化膜的组成,使得含Cr耐蚀钢筋在混凝土模拟孔隙液中的点蚀电位更高,钝化膜更稳定;含Cr耐蚀钢筋的腐蚀产物中α-FeOOH的含量高于HRB400,进一步改善了钢筋耐蚀性。     

机械能助渗锌及其海洋环境防腐蚀效果

对机械能助渗锌的工艺、渗锌层的组织结构、渗锌层在海洋环境中的防蚀性能进行了分析,讨论了机械能对渗锌的作用及合金化对渗层耐蚀性的影响,认为机械能促进了渗层中Zn-Fe合金(主要为FeZn_4相)的形成,渗层中Zn-Fe合金化是其耐蚀性能优异的主要原因,并在与不锈钢对比试验的基础上,总结出机械能助渗锌是海洋环境钢铁紧固件有效的防腐蚀方法.     

自蔓延高温合成陶瓷内衬管耐蚀性研究的进展

自蔓延高温合成技术是制备耐蚀钢管新技术，具有工艺简单，成本低和钢管耐蚀性能好等特点。在总结国内外合成技术的基础上，介绍了自蔓延高温合成陶瓷内衬钢管的原理和提高陶瓷内衬钢管耐蚀性的措施，展望了耐蚀陶瓷内衬钢管在工业生产上的应用。     

耐蚀镁合金研究与应用

综述了镁及其合金的腐蚀,国内外镁合金腐蚀研究现状,提高镁合金耐蚀性的方法,耐蚀镁合金研究与应用发展趋势等方面的情况。期望对耐蚀镁合金有一个较全面的了解。     

一种Cr-Ni合金化耐蚀钢筋在氯盐环境中的腐蚀行为

通过加速腐蚀试验(盐雾和周浸)、电化学试验等方法研究了一种Cr-Ni合金化耐蚀钢筋和普通钢筋HRB400在氯盐环境中的耐蚀性,并通过扫描电镜(SEM)、电子显微探针分析(EMPA)和X射线衍射(XRD)等技术手段分析了锈层的形貌和组成。结果表明:在碱性和中性NaCl溶液中合金化耐蚀钢筋的耐氯离子腐蚀能力较好;在盐雾、周浸腐蚀试验中的腐蚀速率分别为普通钢筋的19.4%和12.3%;普通钢筋加速腐蚀后的锈层较厚,且为单层疏松结构,其锈层主要由Fe_3O_4、α-FeOOH和β-FeOOH构成;而Cr-Ni合金化耐蚀钢筋的锈层相对较薄,为多层致密结构,主要组成为Fe_3O_4、α-FeOOH、β-FeOOH、γ-FeOOH、CrOOH和α-Fe_2O_3;合金元素Cr和Ni通过提高钢筋的自腐蚀电位,降低腐蚀敏感性,促进保护性锈层的产生,提高了钢筋在氯盐环境中的耐蚀性。     

濒海地区混凝土中钢筋锈蚀的电化学综合检测与评价

通过理论探讨及系统试验分析,提出了针对濒海地区混凝土结构中钢筋锈蚀状况的电化学综合检测方法及其评价准则.该方法具有简单、准确、高效的特点,且能与混凝土结构中钢筋的服役寿命建立关联.文中介绍了电化学综合方法的测试步骤、评判标准及其成功运用于濒海工程混凝土钢锈破坏评价的实例.     

提高海洋环境钢筋混凝土构筑物耐久性措施综述

针对海洋环境钢筋混凝土构筑物过早腐蚀破坏,从混凝土防护、钢筋保护、包覆隔离保护、施工技术四个方面综述目前国内外对海洋环境下保护钢筋减少腐蚀、延长构筑物服役寿命所采取的技术措施,内容涉及:高性能混凝土、抗海水腐蚀水泥、阻锈剂、混凝土表面涂层、提高保护层厚度、钢筋涂层、耐腐筋、电化学保护、纤维玻璃钢或钢护筒包覆隔离、预防早期开裂、透水模板。重点讨论各措施的基本原理、特点、主要缺点和发展方向及工程应用。其中海工高性能混凝土是最经济、最基本和不可替代的,其他作为高性能混凝土基本措施的有效补充。     

低合金钢筋在水泥萃取液中钝化膜的耐蚀机理研究

采用动电位极化曲线、Mott-Schottky结合XPS和AES,分析研究了Cr对耐蚀钢筋在水泥萃取液中形成的钝化膜的耐蚀机理。结果表明,随着浸泡时间的延长,钢筋电极的自腐蚀电流密度(Icorr)降低,浸泡1 d后可以形成具有保护性的钝化膜。Cr含量的增加减小了钢筋钝化膜中的载流子密度,提高了其稳定性。Cr含量的增加抑制了Fe2+向Fe3+的氧化过程,从而提高了钢筋钝化膜的耐蚀性。耐蚀钢筋中的Cr参与了钝化膜的形成,稳定钝化膜则主要由Fe的氧化物组成;钝化膜内层为含Cr-Fe的氧化物,外层为Fe的氧化物;钝化膜的厚度在3～4 nm之间,随Cr含量的增加而略微增大。     

Epoxy‐coated bars as corrosion control in cracked reinforced concrete

One of the most common corrosion protection methods in reinforcing concrete bars is the application of fusion‐bonded epoxy coatings. Although considerable research has been carried out on the performance of epoxy‐coated bars (ECR), there are still many uncertainties about their performance in cracked concrete. In this experimental program, reinforcing steel bars with six types of epoxy coatings embedded in concrete slabs with a 0.4 mm wide preformed crack intersecting the reinforcing steel at right angles were tested. Results of corrosion potentials, corrosion current density, coating adhesion tests, chloride content, and visual examination after 68 months of exposure to a simulated marine environment are reported. Results revealed that under the studied conditions the ECR did not provide total protection of steel reinforcement in cracked concrete. Their use however, tended to reduce significantly the damage caused by the chloride‐induced corrosion when compared with the uncoated bars embedded in concrete with similar characteristics.     

Corrosion behavior of austenitic 304L and 316LN stainless steel clad reinforcing bars in cracked concrete

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.     

镁合金在大气环境中电偶腐蚀行为及规律的研究

在北京大气环境下，研究AM60镁合金和不同金属材料（碳钢、不锈钢、黄铜和铝合金）偶接的电偶腐蚀行为规律。研究表明，镁合金作为阳极发生不同程度的电偶腐蚀，通过1a的北京大气环境下的暴露试验后，AM60镁合金的电偶腐蚀效应由强到弱的顺序为：碳钢、黄铜、不锈钢和铝合金，其中镁合金与LY12铝合金偶接的电偶腐蚀效应最小。通过与其它地区室外暴晒的镁合金电偶腐蚀效应的对比，表明环境因素影响着镁合金的电偶腐蚀效应。同时阴极材料、试验时间、试样尺寸（偶接面积）和试验环境都会对镁合金电偶腐蚀效应产生影响。经1a曝晒的AM60镁合金形成了具有保护性的腐蚀产物层阻碍了腐蚀发展。北京地区高自然降尘量导致金属表面湿润时间加大，从而加速了AM60镁合金的电偶腐蚀。采用XRD方法分析表面的腐蚀产物，用金相显微镜和扫描电镜（SEM）观察试样腐蚀后的表面形貌特征和腐蚀产物的结构，并用与之相连的能谱仪分析腐蚀产物中的元素组成。     

节镍型不锈钢钢筋在混凝土环境中腐蚀研究现状及进展

通过参考现有的工程实例,对节镍型不锈钢筋混凝土的应用进行了分析,阐述了目前国内外节镍型不锈钢钢筋在混凝土环境中腐蚀研究的现状、科学问题及其进展,同时对其在后续应用过程中存在的问题进行了探讨,为未来大规模推广使用节镍型不锈钢钢筋混凝土提供参考。     

钢筋阻锈剂的阻锈机理及性能评价的研究进展

钢筋腐蚀是引起钢筋混凝土构筑物提前失效的主要因素,应用钢筋阻锈剂是主要的防腐蚀措施之一。重点介绍了海洋环境中,氯盐的侵蚀机理和阻锈剂的作用机理;讨论了阻锈剂的性能评价方法和应用现状;指出高效且环境友好复合型阻锈剂的合成是今后研究的主要方向,这对于提高我国钢筋混凝土结构耐久性具有重要意义。     

The Impact of Corrosion on the Mechanical Behavior of Welded Splices of Reinforcing Steel S400 and B500<Subscript>c</Subscript>

The reinforcing steel, used in concrete structures, when corroded causes reduction of the strength properties and especially drastic reduction of ductility. Steel corrosion constitutes an important factor of progressive devaluation of its mechanical properties and serious reduction of the integrity of structures. The problem becomes more evident specifically for structures near coastal areas where salt corrosion is predominant. Reinforced concrete columns and beams are quite often extended by welding new steel reinforcement to the already corroded existing steel. In the present article the impact of corrosion on the mechanical properties of welded splices of reinforcing Steel S400 and B500_c is examined. An experimental investigation was conducted and tensile and compressive results are presented for welded precorroded S400 and noncorroded B500_c steel splices. The mechanical behavior of welded splices in tension are different in compression and depend strongly on the level of corrosion of the S400 bars.     

A field study of critical chloride content in reinforced concrete with blended binder

This paper presents the results from the investigation of chloride‐induced reinforcement corrosion in concrete slabs after over 13 years exposure in the marine environment. In the beginning of 1990s over 40 reinforced concrete slabs with different types of binder and water/binder ratios were exposed in a marine environment at Swedish west coast. In this study a new rapid technique was used for non‐destructive measurement of corrosion. Based on the results from the non‐destructive measurement, the actual corrosion of steel bars in five concrete slabs was visually examined and the chloride profiles in the penetrating direction as well as at the cover level were measured. The results show that the visible corrosion normally occurred about 10–20 cm under the seawater level, where the oxygen may be sufficiently available for initiating the corrosion. It is also found that chloride may easily penetrate through a poor interface between concrete and mortar spacer and initiate an early corrosion. As a conclusion, although the chloride level 1% by mass of binder may not be the same as the conventionally defined threshold value, it can be taken as the critical level for significant on‐going corrosion that is visible by destructive visual examination, despite types of binder.     

Corrosion Evolution of Steel Reinforced Concrete Under Simulated Tidal and Immersion Zones of Marine Environment

The corrosion evolution processes of steel reinforced concrete under simulated tidal and immersion zones of marine environment were investigated by using electrochemical measurements and corrosion morphology observations.The results indicate that the corrosion of rebar in concrete under both environments experiences the deterioration from passivation to pitting corrosion and then to general corrosion.Specially,the pitting plays the major role only in the early stage of corrosion,and the general corrosion replaces the dominate role of pitting during the long-term corrosion.In addition,both the pitting depth on local surface and the rust thickness on the overall surface of rebar in the tidal condition are larger than those in immersion condition,which is attributed to the faster corrosion rate in tidal zone caused by the concentrated chloride ions and sufficient oxygen supply.     

超级13Cr钢在高温高压下的抗CO2腐蚀性能

在模拟某油田腐蚀环境中,通过高温高压CO2腐蚀试验,采用SEM、EDS和XPS测试手段分析,研究温度变化对超级13Cr马氏体不锈钢的腐蚀行为的影响。研究结果表明,随着温度的升高：超级13Cr马氏体不锈钢的均匀腐蚀速率呈微上升的趋势,气相环境中试样的均匀腐蚀速率大于液相,但均远小于0．1mm／a,局部腐蚀严重。在温度为150℃的气相环境中,超级13Cr钢最大局部腐蚀速率可达2．1379mm／a,其7天实验的最大局部腐蚀坑深度可达41μm。XPS检测结果显示,超级13Cr钢表面钝化膜主要成分是非晶态的Cr2O3。