技术领域Technical Field
本发明属于钢筋混凝土无损检测领域，更具体地，涉及一种钢筋混凝土加速锈蚀时通电效率的在线监测装置和方法。The invention belongs to the field of nondestructive testing of reinforced concrete, and more specifically, relates to an online monitoring device and method for the power-on efficiency of reinforced concrete during accelerated corrosion.
背景技术Background technique
现代建筑面临的服役环境日益严峻，钢筋腐蚀已成为威胁建筑工程项目最主要、最普遍的病害，针对钢筋锈蚀问题的研究是土木工程混凝土结构耐久性领域长久以来的焦点。为了解钢筋锈蚀对结构性能的影响，从而预测或设计混凝土结构的寿命，试验研究中通常需要制作锈蚀钢筋混凝土构件来进行后续的力学性能或耐久性能测试。然而，自然条件下钢筋锈蚀是一个非常缓慢的过程，即使是极端恶劣的侵蚀环境中，钢筋的锈蚀速率也不超过0.01mA/cm2，导致获取锈蚀钢筋混凝土试件的时间成本大大增加，甚至可以长达数年之久。同时，取自实际工程中的锈蚀钢筋混凝土构件不仅不易获取，并且各种参数记录不详尽，不利于后续分析。这给锈蚀钢筋混凝土结构的试验研究带来了极大障碍。The service environment faced by modern buildings is becoming increasingly severe. Steel bar corrosion has become the most important and common disease threatening construction projects. Research on steel bar corrosion has long been the focus of the durability of concrete structures in civil engineering. In order to understand the impact of steel bar corrosion on structural performance and thus predict or design the life of concrete structures, experimental research usually requires the production of corroded steel bar concrete components for subsequent mechanical properties or durability tests. However, steel bar corrosion is a very slow process under natural conditions. Even in extremely harsh corrosive environments, the corrosion rate of steel bars does not exceed 0.01 mA/cm2 , which greatly increases the time cost of obtaining corroded steel bar concrete specimens, which can even take several years. At the same time, corroded steel bar concrete components taken from actual projects are not only difficult to obtain, but also the various parameters are not recorded in detail, which is not conducive to subsequent analysis. This has brought great obstacles to the experimental research of corroded steel bar concrete structures.
针对上述问题，试验中通常采用加速锈蚀的方法来提高锈蚀速率，从而在短时间内获取锈蚀试件，例如：内掺氯盐法、人工模拟气候(盐雾喷洒、干湿循环、加速碳化室等)、通电加速锈蚀法。其中，内掺氯盐法和人工气候法的可控性较差，无法通过调节时间和环境参数来达到预期锈蚀量，在试验研究中鲜有应用；通电加速锈蚀法建立在法拉第定律的理论基础上，如式(1)所示，通过调节电流密度和通电时间，能够比较准确地控制钢筋的锈蚀量。In order to solve the above problems, the corrosion acceleration method is usually used in the test to increase the corrosion rate, so as to obtain the corrosion specimen in a short time, such as internal chloride salt method, artificial simulated climate (salt spray, dry-wet cycle, accelerated carbonization chamber, etc.), and power-on accelerated corrosion method. Among them, the internal chloride salt method and artificial climate method have poor controllability and cannot achieve the expected corrosion amount by adjusting the time and environmental parameters, so they are rarely used in experimental research; the power-on accelerated corrosion method is based on the theory of Faraday's law. As shown in formula (1), by adjusting the current density and the power-on time, the corrosion amount of the steel bar can be controlled more accurately.
式中，ΔmF为根据法拉第定理计算得到的钢筋的理论质量损失；M为铁的摩尔质量且等于56g/mol；I为电流密度；n是反应电极化学价，即失去的电子数，n＝2；t为通电时间；F为法拉第常数，其值为96500A/s。Wherein, ΔmF is the theoretical mass loss of steel bar calculated according to Faraday's theorem; M is the molar mass of iron and is equal to 56 g/mol; I is the current density; n is the chemical valence of the reaction electrode, that is, the number of electrons lost, n = 2; t is the power-on time; F is the Faraday constant, whose value is 96500 A/s.
实际操作时，仅需将钢筋混凝土构件全浸泡或半浸泡在NaCl溶液中，将钢筋连接直流电源的正极，另用不锈钢或铜片/网连接电源负极，控制电流和时间，即可确定钢筋的锈蚀量。可见，通电加速锈蚀法易于操作、设备简单、原理明确，成为了当下应用最广泛的试验方法。In actual operation, it is only necessary to fully or half-immerse the reinforced concrete components in the NaCl solution, connect the steel bar to the positive pole of the DC power supply, and connect the negative pole of the power supply with stainless steel or copper sheet/net, and control the current and time to determine the amount of steel bar corrosion. It can be seen that the power-on accelerated corrosion method is easy to operate, has simple equipment, and has a clear principle, and has become the most widely used test method at present.
虽然通电加速锈蚀技术已有几十年的应用历史，但是其通电效率(真实锈蚀量与预期锈蚀量的比值)一直饱受争议，无法达成共识。大量的试验研究结果发现通电加速得到的试件锈蚀量与预期值存在较大偏差，通电效率从5％到120％均有报道，不仅变化范围极大，且影响因素并不明确，给通电加速锈蚀技术的推广使用带来许多实际困难。在实际应用中，为了得知钢筋的真实锈蚀量，研究人员不得不将通电加速锈蚀后的钢筋混凝土试件剖开，这种做法不仅费时费力，而且属于破损试验，无法对试件进行后续试验研究(例如加固、锈蚀保护等)。因此，亟需一种能够在不破损试件的前提下实时、准确获知钢筋的真实锈蚀量(或通电加速锈蚀方法的通电效率)的方法。Although the technology of accelerating corrosion by electricity has been used for decades, its efficiency (the ratio of the actual corrosion amount to the expected corrosion amount) has been controversial and no consensus has been reached. A large number of experimental research results have found that the corrosion amount of the specimens obtained by electricity acceleration is greatly deviated from the expected value. The efficiency of electricity acceleration has been reported from 5% to 120%. Not only is the range of variation extremely large, but the influencing factors are not clear, which brings many practical difficulties to the promotion and use of the technology of accelerating corrosion by electricity. In practical applications, in order to know the actual corrosion amount of the steel bars, researchers have to cut open the reinforced concrete specimens after electricity accelerated corrosion. This approach is not only time-consuming and laborious, but also belongs to a destructive test, and it is impossible to conduct subsequent experimental research on the specimens (such as reinforcement, corrosion protection, etc.). Therefore, there is an urgent need for a method that can accurately and in real time know the actual corrosion amount of the steel bars (or the efficiency of the electricity accelerated corrosion method) without damaging the specimens.
发明内容Summary of the invention
针对现有技术的以上缺陷或改进需求，本发明提供了一种钢筋混凝土加速锈蚀时通电效率的在线监测装置和方法，其目的在于，在不损坏试件的情况下，获取钢筋混凝土加速锈蚀过程中的准确通电效率。In view of the above defects or improvement needs of the prior art, the present invention provides an online monitoring device and method for the power-on efficiency of reinforced concrete during accelerated corrosion, the purpose of which is to obtain the accurate power-on efficiency during the accelerated corrosion of reinforced concrete without damaging the test piece.
为实现上述目的，按照本发明的一方面，提出了一种钢筋混凝土加速锈蚀时通电效率的在线监测装置，包括侵蚀溶液、极化回路和测试回路，其中：To achieve the above object, according to one aspect of the present invention, an online monitoring device for the power-on efficiency of reinforced concrete during accelerated corrosion is provided, comprising an erosion solution, a polarization circuit and a test circuit, wherein:
所述侵蚀溶液用于放置钢筋混凝土并使钢筋发生腐蚀反应；The corrosive solution is used to place reinforced concrete and cause the steel bars to corrode;
所述极化回路用于给混凝土中的钢筋施加恒电流，其包括直流电源和导电板，所述直流电源的正极接钢筋，负极接所述导电板，该导电板环绕在混凝土周围并与所述侵蚀溶液接触；The polarization circuit is used to apply a constant current to the steel bars in the concrete, and includes a DC power supply and a conductive plate, wherein the positive electrode of the DC power supply is connected to the steel bars, and the negative electrode is connected to the conductive plate, and the conductive plate surrounds the concrete and contacts the corrosive solution;
所述测试回路用于在极化回路施加恒电流时测试钢筋的电化学参数，其包括电化学工作站、参比电极和辅助电极，所述电化学工作站分别与钢筋、参比电极、辅助电极连接，所述参比电极和辅助电极均置于所述侵蚀溶液中。The test circuit is used to test the electrochemical parameters of the steel bar when a constant current is applied to the polarization circuit. The test circuit includes an electrochemical workstation, a reference electrode and an auxiliary electrode. The electrochemical workstation is connected to the steel bar, the reference electrode and the auxiliary electrode respectively. The reference electrode and the auxiliary electrode are both placed in the corrosion solution.
作为进一步优选的，所述侵蚀溶液具体为NaCl溶液。As further preferred, the etching solution is specifically a NaCl solution.
作为进一步优选的，所述辅助电极为Pt片，所述参比电极为饱和甘汞电极。As further preferred, the auxiliary electrode is a Pt sheet, and the reference electrode is a saturated calomel electrode.
作为进一步优选的，所述导电板具体为铜网。As further preferred, the conductive plate is specifically a copper mesh.
按照本发明的另一方面，提供了一种钢筋混凝土加速锈蚀时通电效率的在线监测方法，其采用上述装置实现，包括如下步骤：According to another aspect of the present invention, there is provided an online monitoring method for the power-on efficiency of reinforced concrete during accelerated corrosion, which is implemented by the above-mentioned device and comprises the following steps:
将钢筋混凝土放置在侵蚀溶液中；通过极化回路对混凝土中的钢筋施加恒电流使钢筋加速锈蚀，令钢筋达到预期锈蚀量；同时通过测试回路实时观察钢筋电位，电位稳定后对钢筋进行电化学测试，获取钢筋表面的锈蚀动力学信息，进而得到钢筋加速锈蚀时的通电效率。Reinforced concrete is placed in a corrosive solution; a constant current is applied to the steel bars in the concrete through a polarization circuit to accelerate the corrosion of the steel bars until the steel bars reach the expected amount of corrosion; at the same time, the steel bar potential is observed in real time through a test circuit, and an electrochemical test is performed on the steel bars after the potential stabilizes to obtain the corrosion dynamics information on the steel bar surface, and then the power-on efficiency when the steel bars are accelerated to be obtained.
作为进一步优选的，所述电化学测试具体为动电位扫描、电化学阻抗谱测试。As further preferred, the electrochemical test is specifically potentiodynamic scanning or electrochemical impedance spectroscopy test.
作为进一步优选的，通过电化学工作站每隔一段时间测试钢筋的线性极化电阻，直至通电结束；根据线性极化电阻计算得到腐蚀电流密度，进而得到用于钢筋腐蚀的电荷量，根据该用于钢筋腐蚀的电荷量和通电所施加的总电荷量，得到加速锈蚀的通电效率。As a further preference, the linear polarization resistance of the steel bars is tested at regular intervals by an electrochemical workstation until the power-on is terminated; the corrosion current density is calculated based on the linear polarization resistance, and then the charge amount for steel bar corrosion is obtained; based on the charge amount for steel bar corrosion and the total charge amount applied by the power-on, the power-on efficiency for accelerating corrosion is obtained.
总体而言，通过本发明所构思的以上技术方案与现有技术相比，主要具备以下的技术优点：In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:
1.本发明通过极化回路给钢筋施加恒电流，实现通电加速锈蚀，同时测试回路测试钢筋电极的电化学参数，两个回路仅共用被测的钢筋电极，彼此独立、互不干扰，同时该两回路的方法测得的电化学阻抗谱数据符合Kramers-Kronig关系，数据准确、可靠；因此本发明可在短时间内快速获取锈蚀钢筋混凝土试件，并在不破损试件的前提下准确获取通电效率以及钢筋的锈蚀量，具有广泛的应用前景。1. The present invention applies a constant current to the steel bar through a polarization circuit to realize accelerated corrosion by power-on, and at the same time, the test circuit tests the electrochemical parameters of the steel bar electrode. The two circuits only share the steel bar electrode to be tested, are independent of each other and do not interfere with each other. At the same time, the electrochemical impedance spectrum data measured by the two-circuit method conforms to the Kramers-Kronig relationship, and the data is accurate and reliable. Therefore, the present invention can quickly obtain corroded steel bar concrete specimens in a short time, and accurately obtain the power-on efficiency and the amount of steel bar corrosion without damaging the specimens, and has broad application prospects.
2.传统的电化学测试需要断开所施加的直流电，等待钢筋电位达到稳定，在开路电位下进行测试，该过程依据电流密度或介质等因素会持续几小时至几十小时不等，不仅耗时，而且不同时间所测得的数据差异性很大；同时断开电流所测得的电化学参数，也即是开路电位下的电化学参数，只能表征通电加速锈蚀之后钢筋的自然腐蚀状态，而不能表征通电过程中钢筋的加速腐蚀状态，二者之间的差异巨大，根据所施加的电流不同，二者测得的腐蚀速率在几十、上百倍以上。而本发明通过双回路的设计实现了在通电加速锈蚀过程中的电化学测试，能够实时在线测得钢筋表面的真实腐蚀速率，得知通电加速锈蚀的作用效率，从而及时调整后续的通电方案，得到预期锈蚀率的钢筋混凝土试件，解决了通电加速锈蚀技术在实际应用中的过程不可控、预期锈蚀量与实际锈蚀量差异大等问题。2. The traditional electrochemical test needs to disconnect the applied direct current, wait for the steel bar potential to reach stability, and test at the open circuit potential. This process will last from several hours to dozens of hours depending on factors such as current density or medium. It is not only time-consuming, but also the data measured at different times are very different. At the same time, the electrochemical parameters measured by disconnecting the current, that is, the electrochemical parameters under the open circuit potential, can only characterize the natural corrosion state of the steel bar after the electric acceleration corrosion, but cannot characterize the accelerated corrosion state of the steel bar during the electric process. The difference between the two is huge. Depending on the applied current, the corrosion rate measured by the two is more than dozens or hundreds of times. The present invention realizes the electrochemical test in the process of electric acceleration corrosion through the design of double circuits, and can measure the real corrosion rate of the steel bar surface in real time online, and know the efficiency of electric acceleration corrosion, so as to timely adjust the subsequent power-on scheme, and obtain the expected corrosion rate of the reinforced concrete specimen, which solves the problems of uncontrollable process of electric acceleration corrosion technology in practical application, and large difference between expected corrosion amount and actual corrosion amount.
3.本发明极化回路中采用铜网，其具有优异的导电性能且便于布置；测试回路中辅助电极采用Pt片，其在电极化作用下电化学稳定性好，参比电极采用饱和甘汞电极，其在NaCl溶液中电势稳定，有利于提高电化学测试准确性。3. The polarization circuit of the present invention adopts a copper mesh, which has excellent electrical conductivity and is easy to arrange; the auxiliary electrode in the test circuit adopts a Pt sheet, which has good electrochemical stability under the action of polarization; the reference electrode adopts a saturated calomel electrode, which has a stable potential in NaCl solution, which is beneficial to improving the accuracy of electrochemical testing.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
图1为本发明实施例钢筋混凝土加速锈蚀时通电效率的在线监测装置结构示意图；FIG1 is a schematic structural diagram of an online monitoring device for power-on efficiency of reinforced concrete during accelerated corrosion according to an embodiment of the present invention;
图2中(a)、(b)分别为本发明实施例通电加速锈蚀过程中所测得的线性极化电阻和腐蚀电流密度；FIG. 2 (a) and (b) are respectively the linear polarization resistance and the corrosion current density measured during the process of accelerated corrosion by power-on according to an embodiment of the present invention;
图3为本发明实施例通电效率随时间的变化示意图。FIG. 3 is a schematic diagram showing changes in power-on efficiency over time according to an embodiment of the present invention.
在所有附图中，相同的附图标记用来表示相同的元件或结构，其中：1-直流电源，2-电化学工作站，3-计算机，4-导电板，5-参比电极，6-侵蚀溶液，7-辅助电极，8-钢筋，9-多孔介质，10-极化回路，11-测试回路。In all the drawings, the same reference numerals are used to represent the same elements or structures, among which: 1-DC power supply, 2-electrochemical workstation, 3-computer, 4-conductive plate, 5-reference electrode, 6-etching solution, 7-auxiliary electrode, 8-steel bar, 9-porous medium, 10-polarization circuit, 11-test circuit.
具体实施方式Detailed ways
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。此外，下面所描述的本发明各个实施方式中所涉及到的技术特征只要彼此之间未构成冲突就可以相互组合。In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
本发明实施例提供的一种钢筋混凝土加速锈蚀时通电效率的在线监测装置，如图1所示，包括侵蚀溶液6、极化回路10和测试回路11，其中：An online monitoring device for the power-on efficiency of reinforced concrete during accelerated corrosion provided by an embodiment of the present invention, as shown in FIG1 , comprises an etching solution 6, a polarization circuit 10 and a test circuit 11, wherein:
所述侵蚀溶液6用于放置钢筋混凝土并使钢筋8发生腐蚀反应；The corrosive solution 6 is used to place reinforced concrete and cause the steel bars 8 to corrode;
所述极化回路10包括直流电源1和导电板4，所述直流电源1的正极接钢筋8，负极接所述导电板4，该导电板4环绕在混凝土周围并与所述侵蚀溶液6接触；需要说明的是，当钢筋不被置于混凝土中，而是直接置于侵蚀溶液中或其他多孔介质9(例如土壤)中时，本发明同样适用。The polarization circuit 10 includes a DC power supply 1 and a conductive plate 4, wherein the positive electrode of the DC power supply 1 is connected to the steel bar 8, and the negative electrode is connected to the conductive plate 4, and the conductive plate 4 surrounds the concrete and contacts the erosion solution 6; it should be noted that when the steel bar is not placed in the concrete but directly placed in the erosion solution or other porous media 9 (such as soil), the present invention is also applicable.
所述测试回路11包括电化学工作站2、参比电极5和辅助电极7，所述电化学工作站2分别与钢筋8、参比电极5、辅助电极7连接，所述参比电极5和辅助电极7均置于所述侵蚀溶液6中。所述电化学工作站2和计算机3里连接，计算机3用于处理获取的电化学参数。The test circuit 11 includes an electrochemical workstation 2, a reference electrode 5 and an auxiliary electrode 7. The electrochemical workstation 2 is connected to the steel bar 8, the reference electrode 5 and the auxiliary electrode 7 respectively. The reference electrode 5 and the auxiliary electrode 7 are both placed in the corrosion solution 6. The electrochemical workstation 2 is connected to a computer 3, and the computer 3 is used to process the acquired electrochemical parameters.
具体的，侵蚀溶液包括但不限于NaCl溶液，其侵蚀性能够使得钢筋发生腐蚀反应；极化回路中的负极连接用于通电加速锈蚀的阳极材料，例如铜网、不锈钢或铂片等；测试回路中的辅助电极包括但不限于Pt片、不锈钢网等，其在电极化作用下电化学稳定性好；测试回路中的参比电极包括但不限于饱和甘汞电极，其在NaCl溶液中电势稳定。Specifically, the corrosive solution includes but is not limited to NaCl solution, whose corrosiveness can cause corrosion reaction of steel bars; the negative electrode in the polarization circuit is connected to an anode material, such as a copper mesh, stainless steel or platinum sheet, which is used to energize and accelerate corrosion; the auxiliary electrode in the test circuit includes but is not limited to a Pt sheet, a stainless steel mesh, etc., which have good electrochemical stability under the action of electrode polarization; the reference electrode in the test circuit includes but is not limited to a saturated calomel electrode, which has a stable potential in NaCl solution.
对于上述双回路装置，其中，极化回路用于钢筋混凝土的通电加速锈蚀，将钢筋连接电源正极，不锈钢板或铜网连接电源负极，施加一定大小的直流电，根据法拉第定律计算通电时间，实现在短时间内令钢筋达到预期锈蚀量；测试回路为三电极电化学测试回路，以钢筋为工作电极，Pt片为辅助电极，饱和甘汞电极为参比电极，采用电化学工作站测试钢筋的线性极化、电化学阻抗谱等一系列电化学测试，获取钢筋表面的锈蚀动力学信息，例如锈蚀电流密度等。For the above-mentioned dual-circuit device, the polarization circuit is used to accelerate the corrosion of reinforced concrete by energizing the steel bar. The steel bar is connected to the positive electrode of the power supply, and the stainless steel plate or copper mesh is connected to the negative electrode of the power supply. A certain amount of direct current is applied, and the power-on time is calculated according to Faraday's law to achieve the expected amount of corrosion of the steel bar in a short time; the test circuit is a three-electrode electrochemical test circuit, with the steel bar as the working electrode, the Pt sheet as the auxiliary electrode, and the saturated calomel electrode as the reference electrode. An electrochemical workstation is used to test a series of electrochemical tests such as linear polarization and electrochemical impedance spectroscopy of the steel bar to obtain corrosion dynamics information on the steel bar surface, such as corrosion current density.
上述两个回路仅共用被测的钢筋电极，彼此独立、互不干扰，保证两个回路的独立性。经过前期检验，采用两回路的方法测得的电化学阻抗谱数据符合Kramers-Kronig关系，证明这种两回路测试方法获取的数据具有可靠性。The above two circuits only share the steel bar electrode to be tested, are independent of each other and do not interfere with each other, ensuring the independence of the two circuits. After preliminary inspection, the electrochemical impedance spectroscopy data measured by the two-circuit method conforms to the Kramers-Kronig relationship, proving that the data obtained by this two-circuit test method is reliable.
考虑介质(裸筋、埋置在混凝土中的钢筋)、混凝土水灰比、电流密度、不同理论锈蚀率、浸泡方式等因素，设计不同条件对钢筋混凝土实施通电加速锈蚀。在实施过程中，测试钢筋的线性极化、电化学阻抗谱等电化学参数，测定其在通电条件下的腐蚀电流密度、电荷转移电阻、混凝土电阻率等参数随着通电时间的变化；如果进行扰动较大的电化学测试，在下一次测试之前注意体系稳定性。通过比较施加的电流密度(或施加的总电量)与测得的腐蚀电流密度(或测得的用于钢筋腐蚀反应的总电量)，可以提前预估加速锈蚀方法的通电效率。Considering factors such as the medium (bare steel bars, steel bars embedded in concrete), concrete water-cement ratio, current density, different theoretical corrosion rates, immersion methods, etc., different conditions are designed to implement electrification to accelerate corrosion of reinforced concrete. During the implementation process, the electrochemical parameters such as linear polarization and electrochemical impedance spectroscopy of the steel bars are tested, and the changes of parameters such as corrosion current density, charge transfer resistance, and concrete resistivity under electrification conditions with the electrification time are measured; if an electrochemical test with large disturbance is performed, pay attention to the stability of the system before the next test. By comparing the applied current density (or the total amount of electricity applied) with the measured corrosion current density (or the measured total amount of electricity used for the steel bar corrosion reaction), the electrification efficiency of the accelerated corrosion method can be estimated in advance.
以下为具体实施例：The following are specific embodiments:
(1)制作一个70mm×70mm×70mm的水泥立方体试块，水灰比为0.3，在中心位置埋置一根直径为12mm的钢筋，钢筋两端涂覆环氧树脂用以绝缘，保证钢筋与水泥之间的接触长度为30mm，面积为11.31cm2。标准养护28d。(1) A 70 mm × 70 mm × 70 mm cement cube was made with a water-cement ratio of 0.3. A steel bar with a diameter of 12 mm was buried in the center. Both ends of the steel bar were coated with epoxy resin for insulation. The contact length between the steel bar and the cement was ensured to be 30 mm and the area was 11.31 cm2 . Standard curing was performed for 28 days.
(2)在通电加速锈蚀之前，将水泥试块放进蒸馏水中浸泡24h，使其充分湿润，降低电阻率。(2) Before applying electricity to accelerate corrosion, soak the cement test block in distilled water for 24 hours to make it fully moist and reduce the resistivity.
(3)采用本发明中的两回路法，对试件进行通电加速锈蚀和电化学测试。其中，将钢筋连接电源正极，铜网环绕在水泥试块周围并连接电源负极，施加密度为0.5mA/cm2的直流电，预计的理论锈蚀率为3％，根据法拉第定律计算得到通电时间为135.38h。(3) The two-circuit method of the present invention is used to conduct power-on accelerated corrosion and electrochemical tests on the specimens. The steel bar is connected to the positive electrode of the power supply, the copper mesh is wrapped around the cement test block and connected to the negative electrode of the power supply, a direct current with a density of 0.5 mA/cm2 is applied, the expected theoretical corrosion rate is 3%, and the power-on time calculated according to Faraday's law is 135.38 hours.
(4)将钢筋、饱和甘汞电极(参比电极)、Pt片(辅助电极)连接至电化学工作站，每隔一段时间测试其线性极化电阻Rp，直至通电结束。利用Stern-Geary公式计算得到腐蚀电流密度icorr，如式(2)所示。将所测得的腐蚀电流密度icorr在时间t上进行积分，得到用于钢筋腐蚀的电荷量QLPR，如式(3)所示。将QLPR除以通电所施加的总电荷量QICAC，可以预测通电加速锈蚀的通电效率η’，如式(4)所示。(4) Connect the steel bar, saturated calomel electrode (reference electrode), and Pt sheet (auxiliary electrode) to the electrochemical workstation, and test its linear polarization resistance Rp at regular intervals until the power-on is terminated. The corrosion current density icorr is calculated using the Stern-Geary formula, as shown in formula (2). The measured corrosion current density icorr is integrated over time t to obtain the charge QLPR for steel bar corrosion, as shown in formula (3). Dividing QLPR by the total charge QICAC applied by the power-on can predict the power-on efficiency η' of accelerated corrosion, as shown in formula (4).
QLPR＝∫icorrAdt (3)QLPR =∫icorr Adt (3)
式中，B表示Stern-Geary常数，A表示钢筋的暴露面积，i表示所施加的恒定电流密度。Where B represents the Stern-Geary constant, A represents the exposed area of the steel bar, and i represents the applied constant current density.
(5)取出钢筋，进行酸洗，得到实际锈蚀量ΔmR，可以通过式(5)得到真实的通电效率η，式中，ΔmF为理论质量损失。(5) The steel bars are taken out and pickled to obtain the actual corrosion amount ΔmR . The real power-on efficiency η can be obtained by equation (5), where ΔmF is the theoretical mass loss.
图2中(a)为通电加速锈蚀过程中所测得的线性极化电阻。从图中可以看出，随着通电时间t的增加，线性极化电阻Rp逐渐增大。采用Stern-Geary公式计算出腐蚀电流密度icorr，绘制腐蚀电流密度icorr随通电时间t的变化，如图2中(b)所示。从图中可以看出，随着通电时间的增加，钢筋表面发生的腐蚀电流密度逐渐降低。采用式(6)所预测出的通电效率η’为34.46％，进而可以预测出试件的真实锈蚀量为1.03％(3％×34.46％)；同时，通过测量质量损失得到真实锈蚀量为0.97％，实际通电效率η为32.24％。由此可见，预测值η’与真实值η之间的误差仅为6％，说明本发明提出的测量方法具有一定的精度和可靠性。Figure 2 (a) is the linear polarization resistance measured during the process of accelerated corrosion by power-on. It can be seen from the figure that with the increase of power-on time t, the linear polarization resistanceRp gradually increases. The corrosion current density icorr is calculated using the Stern-Geary formula, and the change of the corrosion current density icorr with the power-on time t is plotted, as shown in Figure 2 (b). It can be seen from the figure that with the increase of power-on time, the corrosion current density occurring on the steel bar surface gradually decreases. The power-on efficiency η' predicted by formula (6) is 34.46%, and it can be predicted that the actual corrosion amount of the specimen is 1.03% (3%×34.46%); at the same time, the actual corrosion amount obtained by measuring the mass loss is 0.97%, and the actual power-on efficiency η is 32.24%. It can be seen that the error between the predicted value η' and the true value η is only 6%, indicating that the measurement method proposed in the present invention has a certain degree of accuracy and reliability.
对于图2中(b)中所示的腐蚀电流密度icorr，应当注意的是，这里所测得的线性极化电阻和腐蚀电流密度均表征的是钢筋表面真实发生的腐蚀反应动力学信息。换言之，可以认为该腐蚀电流密度是通电加速锈蚀过程中钢筋表面真实发生的腐蚀速度。例如，在通电2小时后测得的腐蚀电流密度icorr为0.25353mA/cm2，而我们所施加的是恒电流密度0.5mA/cm2，那么此时的通电效率为50.71％。根据这个思路，则可以得出通电效率随着通电时间的变化，如图3所示。可见，本发明方法可以实时监测通电过程中通电效率的变化。For the corrosion current density icorr shown in FIG2 (b), it should be noted that the linear polarization resistance and corrosion current density measured here both represent the corrosion reaction kinetic information that actually occurs on the steel bar surface. In other words, it can be considered that the corrosion current density is the actual corrosion rate that occurs on the steel bar surface during the process of accelerated corrosion by power-on. For example, the corrosion current density icorr measured after 2 hours of power-on is 0.25353 mA/cm2 , and we apply a constant current density of 0.5 mA/cm2 , then the power-on efficiency at this time is 50.71%. Based on this idea, it can be concluded that the power-on efficiency changes with the power-on time, as shown in FIG3 . It can be seen that the method of the present invention can monitor the change of the power-on efficiency in real time during the power-on process.
本领域的技术人员容易理解，以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
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