共查询到20条相似文献,搜索用时 15 毫秒
1.
采用圆孔扩张理论对混凝土钢筋锈胀过程进行分析,推导了不同钢筋锈胀量对应的塑性区边界混凝土应力及塑性区半径计算公式,在此基础上建立了混凝土锈胀开裂寿命准则及寿命预测模型。锈胀开裂寿命模型分析表明,预测寿命值与钢筋相对保护层厚度m和混凝土等级有直接关系。随着相对厚度m增加,锈胀开裂预测寿命值增加,并且前期增加较快,后期增加较缓慢。混凝土强度等级对预测寿命值影响显著,随混凝土强度增大,混凝土锈胀开裂寿命增大。工程应用表明,该模型预测寿命可为工程的中度维护提供参考。 相似文献
2.
3.
Corrosion in reinforced concrete structures is a major problem that seriously affects the service life of the structures. In order to detect rebar corrosion, a fiber optic corrosion sensor (FOCS) made of one fiber Bragg grating (FBG) sensor and twin steel rebar elements was designed and packaged up with concrete. Subsequently, a series of experiments were carried out to verify its feasibility. A constant current accelerated corrosion test was performed on five fiber optic corrosion sensors and the relationship between reflected wavelength change from the grating and the weight loss rate of rebar was obtained by the gravimetric weight loss method. The experiment shows that it is feasible to monitor the degree of corrosion of reinforced steel in reinforced concrete structures using FOCS. 相似文献
4.
5.
新型试剂快速冷却螺纹钢的耐蚀性能 总被引:1,自引:0,他引:1
研究了螺纹钢在经冷却剂CQ、水或空气冷却后的耐蚀性能。室外大气暴露实验和干湿交替循环加速腐蚀实验表明,采用试剂CQ冷却的螺纹钢耐蚀性能明显优于水和空气冷却的。XRD、SEM和TPR结果表明,冷却剂对螺纹钢大气腐蚀产物的物相组成无影响,但影响其相对含量,从而改变锈层保护性系数。水冷、空冷和CQ冷螺纹钢的锈层保护性系数分别为0.23、0.27和0.43。因此,试剂CQ冷却的螺纹钢在大气腐蚀过程中生成了相对稳定致密的锈层,从而减缓了腐蚀反应的进行,对螺纹钢起一定的保护作用。 相似文献
6.
Electrochemical investigation of chloride-induced depassivation of black steel rebar under simulated service conditions 总被引:1,自引:0,他引:1
Electrochemical measurements of chloride thresholds are reported in simulated concrete pore solution for as-received and surface-modified rebar in an experimental apparatus designed to simulate service conditions. Surface modification led to higher chloride thresholds and reduced variability. The variability in thresholds for as-received rebar was represented by a log-normal distribution; therefore, simple averages of chloride thresholds, without reference to underlying distribution, might not provide reliable indicators of depassivation. The relative constancy of electrochemical measurements below thresholds, and the dependence of the thresholds on surface conditions, suggests that rebar depassivation is likely caused by local critical chemical conditions at the steel surface. 相似文献
7.
8.
以含氯离子环境下检测到的钢筋均匀腐蚀数据为基础,用平均腐蚀深度对钢筋的锈蚀程度进行了表征。分析了钢筋均匀腐蚀深度的分布类型,建立了均匀腐蚀钢筋的可靠性模型,并进行实例验证分析,得出了一定腐蚀时间下钢筋腐蚀可靠性的发展规律,据此建立了钢筋均匀腐蚀的可靠度计算方法。 相似文献
9.
10.
The corrosion of rebar is one of the primary causes of premature deterioration of the concrete structure. The ideal option to overcome this situation would be to provide corrosion protection right at the time of manufacturing of the rebar before it is encased in the concrete and hence, warrants the use of corrosion resistance rebar.The present paper outlines characterisation of coating obtained on rebar surface from pure Zn and Zn-4.9Al-0.1 misch metal bath. The coating was characterised by SEM, EDS, Galvanostatic and XRD techniques. In case of pure Zn bath, distinct phases such as eta, zeta, delta and gamma 1 and gamma were identified in coating where as in case of Zn-4.9Al-0.1 misch metal bath no such distinctive phases were found. The coating obtained from Zn-4.9Al-0.1 misch metal bath was thinner and consisted of outer Al2O3 phase followed Zn-Al phase resulting in better ductility compare to the coating obtained from pure Zn bath. Comparative corrosion resistance performances of both types of coating respect to uncoated rebar were evaluated by salt spray and tafel test. were conducted in simulated aggressive chloride and concrete pore solution of coated and The coating obtained form Zn-4.9Al-0.1 misch metal bath was found to be more anodic and showed 1.5-3 times better corrosion resistance in concrete pore solution and 2.5 times better resistance against aggressive chloride attack compare to the coating obtained from pure Zn bath. Both the coatings dissolved in faster rate in highly alkaline environment (pH = 13.6) where as dissolution rate decreased with decrease of pH in pore solution. The sacrificial as well as barrier protection of Zn-Al alloy coating was found to be more effective than pure Zn coating. Both types of coated bars showed reduction in bond strength in concrete structure. It is attributed by the faster dissolution of the coating, leading to hydrogen gas evolution thereby creating a gap between the rebar surface and concrete structure. 相似文献
11.
热轧带肋钢筋是我国产量最大的钢材产品,而提高钢筋产品质量并降低生产成本一直是技术创新的动力。为了使高强度钢筋轧制工艺和装备适应我国热轧带肋钢筋新标准的要求,对其控轧控冷工艺进行了探讨,对现有棒材轧机进行改造的工艺进行了详细分析,比较了切分轧制和高速轧制两种工艺的优缺点,提出了工艺布置新思路,为新钢筋生产线工艺设计,老线改造设计,或者钢铁企业工程技术人员开发品种提供了独特的途径。 相似文献
12.
介绍了陕钢集团汉中钢铁有限责任公司近年来在建材生产过程中遇到的钢筋易锈蚀、锚杆钢不圆度超标、切分轧制钢筋表面折叠等典型质量问题及其采取的解决措施。采用这些措施后,产品质量得到了很大提升。 相似文献
13.
14.
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
15.
环氧涂层钢筋及其应用 总被引:5,自引:0,他引:5
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。 相似文献
16.
HRB400钢筋缩颈-滚压直螺纹机械连接工艺已在实际建筑工程中被广泛应用。国家大力推广的HRB500钢筋缩颈-滚压直螺纹机械连接的产品性能稳定性较差。通过计算机数值模拟的方法研究了HRB500钢筋在缩颈工序过程中的金属流动情况,从宏观表现和微观特征两个方面研究了HRB500钢筋直螺纹机械连接失效断口,明确了连接失效的原因。缩颈时钢筋横肋的金属流动速度不同,形成显微裂纹,造成应力集中,缩颈过程中塑性变形极其不均匀,降低了其拉伸塑性;提出了剥肋-缩颈-滚压直螺纹的钢筋机械连接优化工艺,给出了Ф32 mm以上钢筋剥肋后,为母材直径+2 mm的合理剥肋工艺参数。 相似文献
17.
通过盐水条件下钢筋的快速腐蚀试验,研究了钢筋在不同水灰比、不同掺料合料掺量以及掺入RI—IC2型阻锈剂情况下钢筋的锈蚀行为.结果表明,水灰比是影响钢筋腐蚀的重要因素之一,相同条件下水灰比越大,钢筋锈蚀越严重;掺入粉煤灰和硅粉后,可有效降低钢筋的腐蚀率;RI—IC2型阻锈剂有良好的阻锈效果,相同掺量下,水灰比越大,其阻锈效果越明显. 相似文献
18.
A simplified system was proposed for measuring a normal strain from the location of a laser beam spot diffracted by a diffraction grating attached to the surface of a specimen. An He-Ne laser beam illuminated the grating and the ± 1-order diffracted beam spots were measured with a single PCD (plasma-coupled device) optical sensor connected with a personal computer. The diffracted intensity distribution was approximated by a Gaussian function and the x-coordinate of its principal axis was used as the location of the spot. The strain of a cantilever beam specimen measured bythis method agreed well with the theoretical value and that measured with a strain gage. 相似文献
19.
20.
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. 相似文献