新型钢筋阻锈剂的合成及其阻锈性能的研究

合成了一种含有氨基和羧基的有机阻锈剂，并通过试验用硬化砂浆法研究了废阻锈剂在掺有氯离子的砂浆中对钢筋锈蚀的抑制作用，同时与常用的亚硝酸盐的阻锈敏柴进行了比较。结果表明，浚新型阻锈剂能够有效地阻止钢筋表面钝化膜的破坏，比亚硝酸盐具有更好的阻锈效果。     

高分子钢筋阻锈剂的合成及其阻锈性能的研究

本文合成了一种含有氨基、酰胺基和羧基的复合型液体高分子阻锈剂,并通过试验用新拌砂浆法研究了该阻锈剂在掺有氯离子的砂浆中对钢筋锈蚀的抑制作用,同时与常用的亚硝酸盐的阻锈效果进行了比较。结果表明,该新型阻锈剂能够有效地阻止钢筋表面钝化膜的破坏,比亚硝酸盐具有更好的阻锈效果。     

HQ型阻锈剂对碱激发水泥混凝土性能的影响

论文探索了HQ型阻锈剂对碱激发混凝土的工作性能、凝结时间、力学性能、碳化深度、砂浆自由氯离子含量及砂浆钢筋锈蚀性能的影响,通过SEM及MIP微观结构测试研究了HQ型阻锈剂对碱激发水泥微观结构的影响。结果表明:HQ型阻锈剂对混凝土的力学性能、碳化及砂浆各龄期自由氯离子含量无显著影响,可提高水泥混凝土的工作性能、缩短混凝土凝结时间,HQ型阻锈剂可使水泥浆体更加密实、降低总孔隙率,从而提高碱激发水泥混凝土的抗锈蚀性能。     

新型迁移型钢筋阻锈剂对混凝土耐久性能的影响

采用半电池电位和线性极化法研究了表面涂覆型钢筋阻锈剂对混凝土中钢筋锈蚀的抑制效果,通过混凝土各层中的氮含量分布分析阻锈剂在混凝土中的迁移渗透性能,并研究阻锈剂对混凝土抗压强度及抗氯离子渗透性能的影响。研究结果表明,该迁移型阻锈剂在混凝土中具有良好的迁移渗透性能,能降低锈蚀钢筋的腐蚀电流,有效抑制钢筋锈蚀发展。在混凝土表面涂覆阻锈剂后,混凝土的抗氯离子渗透性能提高,对混凝土抗压强度基本没有影响。     

不同胶凝材料中的钢筋阳极极化电位-时间关系曲线

采用钢筋锈蚀快速试验方法(新拌砂浆法),检验了纯水泥砂浆以及分别掺加减水剂、阻锈剂、粉煤灰、矿渣粉、复合矿物质掺合料(粉煤灰+矿渣粉)、复合矿物质掺合料和阻锈剂、复合矿物质掺合料+NaCl+阻锈剂等不同胶凝材料砂浆中钢筋的电极电位随时间变化的关系曲线,由此得出,纯水泥砂浆、掺减水剂砂浆、掺阻锈剂砂浆以及掺复合矿物掺合料和阻锈剂砂浆对钢筋无害并有保护作用,其他砂浆中的钢筋会有锈蚀倾向.     

不同环境下有机防护型阻锈剂阻锈效果研究

钢筋锈蚀导致的结构破坏日趋严重。使用阻锈剂是防止锈蚀的一种主要手段,试验采用有机防护型阻锈剂,通过分析碳钢电极在不同阻锈剂浓度、pH值、Cl-浓度以及不同温度时混凝土模拟孔溶液中的电化学行为,利用交流阻抗谱法分析有机防护型阻锈剂的阻锈效果。研究得出,有机防护型阻锈剂能有效的防止钢筋锈蚀,且随着阻锈剂浓度的增加,阻锈效率逐渐升高;随着模拟孔溶液pH值的增大,阻锈效率呈先增大后减小的趋势,在pH=11.3时达到最大;考虑氯离子浓度和温度不同的影响时,得到在氯离子浓度为3.5%、温度为25℃时阻锈效率最大。通过试验研究全面分析了在不同环境下有机防护型阻锈剂的阻锈效果,为有机防护型阻锈剂的广泛应用提供了科学依据。     

新型钢筋阻锈剂的阻锈性能研究

通过动电位扫描、恒电流阳极极化和失重法评价了自制的LN有机复合型钢筋阻锈剂在模拟孔溶液和砂浆中的阻锈效果,并探讨了阻锈机理.研究结果表明,LN钢筋阻锈剂能延长钢筋发生锈蚀的时间,降低钢筋的腐蚀速率,具有良好的阻锈性能,对砂浆的抗折、抗压强度无不利影响.     

钢筋阻锈剂阻锈性能快速评价方法对比研究

依据国内相关阻锈剂标准,对钢筋阻锈剂阻锈性能快速评价方法中的盐水浸渍试验和钢筋锈蚀快速试验(硬化砂浆法)进行了对比试验研究。结果表明:在盐水浸渍试验中,仅采用钢筋锈蚀指标可用于各类阻锈剂阻锈性能的初步判定;在钢筋锈蚀快速试验(硬化砂浆法)中,建议提高JT/T 537—2004标准中氯化钠掺量至水泥的3%,阻锈剂掺量取3%或推荐掺量。两种方法都能在一定程度上区分各种阻锈剂的阻锈性能,其中本研究建议的钢筋锈蚀快速试验(硬化砂浆法)更为严格一些。在进行阻锈剂品种的初步选择时,建议采用两种方法进行试验,并选择两种方法均认为有较好阻锈效果的阻锈剂。     

有机钢筋阻锈剂在混凝土中的阻锈性能及其对混凝土性能的影响

采用半电池电位和线性极化法监测钢筋在掺有有机钢筋阻锈剂的混凝土中的锈蚀时间,研究有机钢筋阻锈剂在混凝土中的阻锈性能,并研究阻锈剂对混凝土工作性能、力学性能、抗渗性能、干燥收缩和水泥水化热的影响。研究结果表明:该有机钢筋阻锈剂能降低钢筋的腐蚀速率,延长钢筋发生锈蚀的时间,具有优良的阻锈效果。掺入该阻锈剂后,混凝土的工作性能有一定程度的改善,抗氯离子渗透性能得到提高,水泥水化热略有降低,收缩也略有减小,对混凝土的抗压强度基本没有影响。     

单氟磷酸钠的阻锈试验研究

采用硬化砂浆法考察了氯离子浓度对钢筋锈蚀性能的影响,并分别对单氟磷酸钠单掺以及单氟磷酸钠与阻锈剂CIA和CIB的1种或2种复掺时的阻锈效果进行了研究.结果表明:未加阻锈剂时,当氯化钠浓度大于1.0%时,钢筋将发生锈蚀:单掺单氟磷酸钠时,阻锈效果随单氟磷酸钠的掺量(0.5%～1.5%)增加而增强,随氯化钠浓度的增大而减弱;阻锈剂复合掺加具有协同作用,即对钢筋的阻锈效果(单氟磷酸钠+CIA+CIB)＞(单氟磷酸钠+CIA)＞(单氟磷酸钠+CIB)＞单氟磷酸钠.     

掺防冻剂混凝土钢筋腐蚀程度的评价

含氯盐及亚硝酸盐混凝土中。通过加速腐蚀试验肉眼观察确定了抑制钢筋腐蚀所需临界摩尔浓度NO^-2／Cl^-比。试验结果表明,随着氯离子含量的增加,抑制钢筋腐蚀所需临界摩尔浓度越高。当氯离子含量达到4kg／m^3时,NO^-2／Cl^-摩尔比约大干1．2时能够完全抑制混凝土中钢筋腐蚀。     

Influence of detection methods on chloride threshold value for the corrosion of steel reinforcement

The aim of this study is to evaluate the influence of depassivation detection methods on chloride threshold value for the corrosion of steel reinforcement in a concrete. The detection methods of depasstivating steel reinforcement have been examined including electrochemical impedance spectra (EIS), potentiodynamic polarization (PP) in a simulated concrete pore solution and half-cell potential, linear polarization (LP) and electrochemical impedance spectra (EIS) in the concrete contaminated by chloride ions. The results have indicated that in a saturated Ca(OH)₂ solution, the chloride threshold value for the corrosion of steel reinforcement concluded by the potentiodynamic polarization is 0.02 mol/L, which is identical with that decided by EIS. However, in the chloride contaminated concrete, no agreement among the chloride threshold values determined by the three detection methods mentioned above can be found. The range of the values decided by half-cell potential is relatively lower than those by the others, besides, the highest values have been obtained by EIS.     

Influence of CaCl2 and NaCl from different sources on chloride threshold value for the corrosion of steel reinforcement in concrete

The influence of CaCl₂ and NaCl from internal and external sources on the chloride threshold value for the corrosion of steel reinforcement in concrete has been investigated. The onset of active corrosion for the steel reinforcement has been detected by half-cell potential and linear polarization methods. Also, the threshold value with different indices, such as free chlorides, [Cl^?]/[OH^?], total chlorides and [Cl^?]/[H⁺] has been measured. It has been found that the chloride threshold values for the corrosion of the specimens with CaCl₂ and NaCl from different sources depend on the indices. Especially, the critical [Cl^?]/[H⁺], i.e. the ratio of acid soluble chlorides to acid neutralisation capacity irrespective of the type and different sources of chloride salt approximately keeps constant at 0.02.     

Improving the durability of concrete by using inhibitors

Corrosion of steel in concrete is one of the major causes of premature deterioration of reinforced concrete structures, leading to structural failure. Various methods are being used to extend the service life of reinforced concrete structures, which include surface coatings to concrete surface, coatings to the reinforcement, cathodic protection, chloride removal and corrosion inhibitors. Of these methods, the use of corrosion inhibitors is found to be one of the effective methods to control rebar corrosion. An attempt has been made to study the performance of the anodic inhibitors (sodium nitrite and zinc oxide), cathodic inhibitors (mono ethanol amine, diethanol amine and tri ethanol amine) and mixed inhibitors to control rebar corrosion. Compressive strength test, tensile strength test, chloride diffusion test and macro cell corrosion test were conducted by varying the type of inhibitors and varying the concentration of inhibitors. The addition of inhibitors not only increased the compressive strength of the concrete but also improved the corrosion resistance properties.     

氯盐侵蚀混凝土结构延寿技术初探Ⅱ——混凝土中6种胺类有机物电迁移与阻锈性能

采用有机元素分析仪、快速氯离子测定法(RCT)、电化学阻抗谱法(EIS)和弱极化法,研究6种胺类有机物在混凝土中的电迁移能力、氯离子的排除情况及通电前后钢筋锈蚀的变化情况.结果表明:相同条件下,不同的胺类阻锈剂在混凝土中的电迁移能力和存留能力不同,且胺类阻锈剂种类对氯离子的排除影响不大;双向电渗技术的除氯效果比电化学的除氯效果弱,但双向电渗后钢筋附近混凝土孔隙液中阻锈剂的含量是氯离子含量(质量摩尔浓度)的2～7倍;双向电渗后混凝土保护层电阻增大,钢筋的锈蚀速度由通电前的电荷传递过程控制转变为氧气在混凝土中的渗透速度控制,钢筋的腐蚀电位显著提高,从而使钢筋的耐蚀性能得以提高.     

Performance of generic and proprietary corrosion inhibitors in chloride-contaminated silica fume cement concrete

This paper presents the results of a study conducted to evaluate the improvement in corrosion-resistance of chloride-contaminated silica fume cement concrete due to the use of corrosion inhibitors. Three proprietary and one generic corrosion inhibitors were evaluated for their performance in inhibiting reinforcement corrosion in the silica fume cement concrete specimens contaminated with 0.4%, 1%, and 2% chloride concentration, by weight of cement. Some of the specimens were subjected to wetting and drying cycles and reinforcement corrosion was monitored by measuring corrosion potentials and corrosion current density. Another batch of concrete specimens was partially immersed in the chloride solution and reinforcement corrosion was accelerated by impressing an anodic potential of 2 V. The extent of corrosion increased with increasing chloride contamination in the concrete specimens. Incorporation of inhibitor generally decreased the rate of reinforcement corrosion. The rate of reinforcement corrosion in the concrete specimens incorporating an organic inhibitor that was added to the concrete during mixing was the least followed by that in the concrete specimens on which a penetrating corrosion inhibitor was applied. Further, the accelerated impressed current technique was noted to be suitable for quickly screening the performance of corrosion inhibitors.     

含氯盐混凝土碳化过程钢筋锈蚀阈值与使用寿命预测

采用10倍水溶解钢筋周围混凝土粉末的方法制取混凝土孔溶液,研究了含氯盐混凝土碳化过程中使钢筋锈蚀的游离氯离子与氢氧根含量比值阈值,结果发现,置于普通硅酸盐水泥混凝土、大掺量工业废渣普通水泥混凝土及硫铝酸盐水泥混凝土使钢筋锈蚀[Cl-][OH-]阈值分别是0.386、0.348和0.138;测得的[Cl-][OH-]阈值比以往他人取得的0.60的结果低;应用[Cl-][OH-]碳化经时模型预测含氯盐混凝土使用寿命明显低于不含氯盐混凝土,其中大掺量工业废渣含氯盐水泥混凝土由于可碳化物少和碳化对游离氯离子释放双重效应使其使用寿命较普通水泥混凝土低,研究结果对大气环境下含氯盐混凝土使用寿命预测和耐久性设计具有参考意义。     

A time-saving method to determine the chloride threshold level for depassivation of steel in concrete

The chloride threshold level is an essential influence on the service life of concrete structures exposed to chloride environment, hence it is important to develop a time-saving method for its measurement. A low voltage electro osmosis method was developed to accelerate the migration of chloride ion in concrete and to increase chloride content to the threshold level in this work. Both macrocell and microcell current measurements were used to confirm the corrosion initiation status of steel. As a result, the chloride content on surface of the soaked working electrode, which could be obtained within 5 days, was found to be an effective indicator for chloride threshold level.     

钢筋混凝土中钢筋的氯诱导腐蚀

钢筋的氯诱导腐蚀是钢筋混凝土中钢筋腐蚀的最主要的原因之一，它会引起钢筋表面钝化膜的局部破损。混凝土中氯离子来自于采用的受污染的原材料和外界环境中氯离子的渗入。测定氯离子的阀值是众多研究的主要目标之一。由于氯离子阀值受许多因素影响，目前尚无确定的阀值。因此，对受氯离子污染的混凝土来说，对氯离子的活性及钢筋的状态的监测尤其重要。许多电化学方法，例如半电池电势、直流极化电阻、电化学阻抗谱和静电脉冲技术等已经广泛应用于研究和现场监测中，实践证明这些技术也是非常有力的工具。本文对钢筋氯诱导腐蚀的现状作了详细概述。