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钢筋在混凝土模拟孔溶液中的腐蚀研究 总被引:1,自引:0,他引:1
钢筋锈蚀是影响混凝土结构耐久性的主要因素.研究了模拟孔溶液pH值、Cl-浓度、SO2-4浓度以及空气等对钢筋锈蚀的影响.试验结果表明:随溶液pH值降低,钢筋锈蚀程度增加.随孔溶液中Cl-浓度增加,锈蚀钢筋增重率线性增加.依据钢筋增重率判断,Cl-导致钢筋锈蚀临界值为0.065%.氯盐溶液中SO2-4存在使钢筋锈蚀速度变为原来的2~3倍.将腐蚀溶液中钢筋与空气隔绝将延缓钢筋锈蚀. 相似文献
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采用恒电位驱动氯离子渗透并加速钢筋锈蚀来模拟海洋钢筋混凝土锈蚀,研究了水胶比、保护层厚度和钢筋直径对试件锈胀开裂的影响;利用COMSOL Multiphysics软件建立了真实骨料混凝土模型并进行数值模拟.结果表明:本试验制备的混凝土试件在恒电位加速锈蚀下钢筋发生非均匀锈蚀并导致混凝土产生3条主裂缝,钢筋临界锈胀应力为2.85~3.51 MPa,开裂时间为190~311 h,降低水胶比及增大保护层厚度均可延缓锈胀开裂时间;数值模拟可以很好地再现钢筋混凝土非均匀锈蚀过程,其获得的锈胀应力演变及混凝土开裂模式与试验结果吻合. 相似文献
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氯盐环境下桥梁混凝土结构的腐蚀行为及破坏机理 总被引:3,自引:2,他引:1
为了解决氯盐导致钢筋混凝土结构耐久性破坏的问题,通过测试处于氯盐侵蚀环境中混凝土内部Cl-含量、pH值及含碱量的分布规律,探讨了氯盐对混凝土结构的腐蚀行为和破坏机理;揭示了氯盐侵蚀下钢筋混凝土曲线桥梁过早劣化的机理,并对此类病害的防治及治理提出了合理建议.结果表明:干湿循环条件下,大量Cl-侵入混凝土内部并且到达钢筋表面,造成钢筋锈蚀、混凝土胀裂,且随Cl-含量增加,混凝土pH值下降,含碱量增大;在含有Cl-的区域,混凝土pH值均降低;氯盐入侵后,增大了混凝土碱骨料破坏的可能性,混凝土内部孔结构发生了明显粗化. 相似文献
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描述了两种不同材料所作的钢筋混凝土(养护时间为28d)放在60℃高温的NaCl溶液中,外加12v的恒压电源,在实验结束这段时间内观察两种钢筋混凝土的锈蚀情况并用钢筋锈蚀仪测量两种混凝土的电位走势从而判断其锈蚀程度。结果表明温度对钢筋锈蚀速度有很大的影响,总体上看,透水混凝土锈蚀程度比普通混凝土要大。 相似文献
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《Construction and Building Materials》2007,21(8):1825-1832
This paper presents results of a study conducted to evaluate the effect of chloride concentration in soil on corrosion of reinforcing steel in concrete. Concrete specimens prepared with Type I, Type V and silica fume cements were exposed to soil with a chloride concentration of up to 3%. The effect of chloride concentration in soil on corrosion of reinforcing steel was evaluated by measuring corrosion potentials and corrosion current density. After 18 months of exposure, the concrete specimens were broken and the extent of corrosion of the reinforcing steel was examined and the gravimetric weight loss due to corrosion was assessed. As expected, the degree of corrosion increased with the chloride concentration in the soil. The type of cement also influenced the extent of reinforcement corrosion. For a particular chloride concentration, least reinforcement corrosion was noted in the silica fume cement concrete followed by Type I and Type V cement concrete. Based on the data developed in this study chloride threshold values in soil for the three types of cements investigated are suggested. 相似文献
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针对氯盐和硫酸盐耦合作用下钢筋混凝土的腐蚀问题,设计制作了含水泥净浆保护层的水泥净浆-钢筋试件,测试了试件在氯盐和硫酸盐腐蚀溶液中的电化学阻抗谱(EIS),并分析了溶液类型、水灰比及水泥净浆保护层厚度对试件电化学参数及钢筋锈蚀程度的影响.结果表明:同单一氯盐溶液中的试件相比,在硫酸盐-氯盐复合溶液腐蚀前期,试件内钢筋表面电荷转移电阻较大,腐蚀电流密度较小,此时硫酸盐减缓了水泥净浆内钢筋的锈蚀进程;在硫酸盐-氯盐复合溶液腐蚀后期,试件内钢筋表面电荷转移电阻显著减小,腐蚀电流密度明显增加,此时硫酸盐加速了水泥净浆中钢筋的锈蚀进程.此外,试件中水泥净浆水灰比越大,钢筋锈蚀程度也越大,当水泥净浆保护层厚度增加时,钢筋锈蚀程度降低. 相似文献
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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。 相似文献
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Chien-Kuo Chiu Fung-Chung Tu Yu-Tai Zhuang 《Structure and Infrastructure Engineering》2016,12(2):188-207
The main purpose of this work is to propose an estimating procedure that building designers can use to choose methods of suppressing chloride ingress, i.e. concrete-cover thickness, concrete-surface coating and concrete mix (water–cement ratio), for reinforced concrete (RC) buildings with a specified durability performance. At first, the authors build equations for estimating airborne chloride concentrations in coastal regions in Taiwan by regressing measurement data. Then, an analytical model incorporates these data into a deterioration model for chloride-induced corrosion and to estimate corrosion of reinforcing steel bars. This work also presents a novel computational procedure to calculate the risk of corrosion for reinforcing steel bars embedded in concrete, while considering uncertainties in environmental conditions, material properties and model error. Using risk curves of corrosion, building designers can set an allowable durable reliability to determine the minimal required concrete-cover thickness for RC members. Finally, this work adopts coastal regions in Taiwan as an example to determine the minimum required concrete-cover thicknesses. Furthermore, reliability-based methods of suppressing chloride ingress for RC buildings are also suggested for each division zone of Taiwan. 相似文献
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用丝束电极模拟混凝土中钢筋表面的不同位置,研究了浸于pH=12,浓度为10%的NaCl溶液中直至9d的混凝土中钢筋的锈蚀状况.通过测量丝束电极的自然腐蚀电位、极化电阻、腐蚀电流,以及在丝束电极探头附近混凝土的密实性、孔溶液的pH值和Cl^-含量的取样分析,研究了由于混凝土的不均匀性造成Cl^-在其中扩散的不均匀性所致的钢筋锈蚀状况.结果表明:混凝土保护层越厚,则电极自然腐蚀电位越高,钢筋实际锈蚀状况也越轻;在混凝土密实性较高区域的孔溶液PH值相对较高,Cl^-含量较低,由于该区域电极的自然腐蚀电位较高,因而电极的实际腐蚀状况较轻,而在混凝土密实性较低的区域,情况则刚好相反. 相似文献
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《Structure and Infrastructure Engineering》2013,9(11):1446-1454
AbstractSteel reinforcing bars in concrete are protected from corrosion by a thin oxide film that is created on the steel surface in the highly alkaline environment of the concrete. Corrosion process begins once this oxide film is destroyed, for example, by chloride ions penetrating from the element surface into the concrete and to the steel rebar. Critical chloride concentration is highly variable owing to numerous factors such as the type of reinforcing steel used. The TransChlor® software is used to simulate the time history of chloride ion ingress and corrosion initiation into a typical reinforced concrete structural element with four different types of reinforcing steel, namely, carbon steel, ferritic stainless steel (1.4003) with rolling skin, duplex stainless steel (1.4462) and ferritic stainless steel (1.4003) with pickled surface. A climate model is used to simulate two different exposure conditions of the structural element, namely direct and mist exposure, representatives for winter conditions in mountainous and lowland areas. A probabilistic method is applied to consider uncertainty of material properties in the model. The results show that reinforcing steel bars with enhanced corrosion performance significantly improve the durability of reinforced concrete. 相似文献
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通过在实验室浸泡的方法,对不同应力状态下、不同水灰比的普通硅酸盐混凝土试件进行抗氯离子侵蚀试验,研究不同强度等级混凝土在应力和氯离子侵蚀的共同作用下氯离子的扩散规律和分布规律。研究发现:在压应力状态下,氯离子含量会随压应力增大而减小,相反,在拉应力状态下,氯离子含量会随拉应力的增大而增大,但随着切片深度的增加,这种影响会逐渐减弱。在抗氯离子侵蚀性能方面,高强度混凝土对应力的影响更敏感。所得到的不同应力状态下、不同切片深度的混凝土结构中氯离子浓度分布,可为推导扩散系数和评估钢筋锈蚀程度提供分析依据。 相似文献
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Exposure of reinforced concrete structural elements to high temperatures, e.g. fire, remains one of the serious potential risks to such structures. This exposure can lead to losses in concrete structural capacity, possible plastic deformation of embedded steel and loss of bond between reinforcing steel and concrete. The level of temperature and the method of extinguishing the fire alter the microstructure of reinforcing steel bars. This microstructure alteration changes the corrosion behavior of steel in such structures, when exposes to chloride ions. The present study was undertaken to determine the impact of exposure of steel to high temperature and the method of extinguishing the fire on its corrosion behavior in alkaline environment of concrete in presence of chloride ions. Results indicated that exposure of steel to high temperatures, regardless of its level; made steel more susceptible to corrosion compared to the reference case, when steel was kept at room temperature. The worst case happened for the steel exposed to 850 °C for an hour, then cooled rapidly in water, where the corrosion rate increased approximately 60% in chloride contaminated concrete pore solution. 相似文献