鋼筋混凝土結構強制電流陰極腐蝕控制系統(tǒng)
發(fā)布時間：2018-10-31 20:24
【摘要】：鋼筋腐蝕是降低鋼筋混凝土結構耐久性的主要原因，，陰極保護（Cathodic Protection,CP）是迄今能夠直接阻止鋼混結構腐蝕的唯一有效途徑。確保強制電流陰極保護（Impressed Current Cathodic Protection，ICCP）系統(tǒng)精確可靠的核心問題在于高效耐久陽極材料的研制和ICCP系統(tǒng)電場投放精確的模擬。本文采用理論研究、數值模擬與試驗驗證相結合，制備了多尺度碳/水泥復合陽極材料，并對ICCP的電場投放進行了系統(tǒng)研究。 首先，分析了單摻碳纖維、納米碳黑、碳納米管水泥復合材料的導電性能，根據其導電機理，結合經濟性和可施工性，進而制備了多尺度碳/水泥復合陽極材料。通過加速極化試驗對多尺度碳/水泥復合陽極材料的抗極化性進行研究，并采用SEM、EDS等對陽極材料的極化機理進行了分析。結果表明，陽極材料的極化過程包括三個階段，前兩個階段分別由于水泥基體含水率的升高、陽極材料內部反電場的形成致使陽極材料的極化電位緩慢上升，第三階段則由于碳纖維被氧化導致試件極化電位驟升，前兩個階段的穩(wěn)定期為陽極材料的有效服役期。此外，在極化過程中多尺度碳/水泥復合陽極材料對侵蝕離子Cl-具有抗干擾性。結合極化性能，確定多尺度碳/水泥復合陽極材料的理想配比為CF03CNT15CB2，該摻量的陽極材料在1200mA/m2極化電流和PH值為13.5的極端環(huán)境下，其穩(wěn)定期可達200h以上。 其次，通過對ICCP系統(tǒng)投放電場Laplace方程和COMSOL的腐蝕模塊二次電流接口原理的分析，建立了ICCP系統(tǒng)電場投放的COMSOL數值模擬方法。將實測的陽極極化曲線和復雜腐蝕狀態(tài)下的陰極極化曲線加載在電極反應界面，采用自由四面體剖分網格，利用COMSOL穩(wěn)態(tài)求解器，建立了ICCP電場投放的數值計算模型。運用COMSOL后處理程序，對鋼筋表面電位和電流密度、混凝土的電場分布進行了分析。結果表明，臨近陰陽極的混凝土區(qū)域的電場最強，而鋼混界面的電流密度最大。ICCP系統(tǒng)通過臨近鋼筋表面局部區(qū)域所鋪設陽極材料實現對鋼筋的有效保護。 最后，根據所建立的ICCP腐蝕控制系統(tǒng)電場投放的COMSOL數值模型，結合所制備多尺度碳/水泥復合陽極材料，搭建了T型梁和空心圓柱ICCP腐蝕控制原型系統(tǒng)，并對鋼筋表面電位進行了數值模擬和試驗結果對比。結果表明除了T型梁上個別測點外相對誤差均在20%以內，試驗驗證了ICCP腐蝕控制系統(tǒng)COMSOL數值模型的可靠性。此外，根據歐美陰極保護標準中的保護電位準則和100mV極化衰減準則，通過測量鋼筋表面的半電池電位和20h的極化衰減值，對所搭建的ICCP系統(tǒng)鋼筋腐效果進行了評價。結果表明，通過ICCP腐蝕控制電場投放的優(yōu)化設計，可實現對T型梁和空心圓柱等典型構件腐蝕的合理保護,所制備的多尺度碳/水泥復合陽極材料可用于工程實踐。
[Abstract]:The corrosion of steel bar is the main reason to reduce the durability of reinforced concrete structure. Cathodic protection (Cathodic Protection,CP) is the only effective way to directly prevent the corrosion of steel concrete structure. The key to ensure the accuracy and reliability of (Impressed Current Cathodic Protection,ICCP) system lies in the development of high efficiency durable anode material and the accurate simulation of electric field in ICCP system. In this paper, multi-scale carbon / cement composite anode materials were prepared by theoretical study, numerical simulation and experimental verification, and the electric field of ICCP was systematically studied. Firstly, the conductive properties of carbon fiber, carbon black and carbon nanotube cement composites were analyzed. According to its conductive mechanism, the multi-scale carbon / cement composite anode materials were prepared according to its conductive mechanism, economy and constructability. The polarization resistance of multi-scale carbon / cement composite anode materials was studied by accelerated polarization test, and the polarization mechanism of the anode materials was analyzed by SEM,EDS et al. The results show that the polarization process of the anode material consists of three stages. The polarization potential of the anode material increases slowly in the first two stages due to the increase of the moisture content of the cement matrix and the formation of the antielectric field inside the anode material. In the third stage, the polarization potential of the sample increases sharply due to the oxidation of carbon fiber, and the stable period of the first two stages is the effective service period of the anode material. In addition, the multi-scale carbon / cement composite anode material has anti-interference to the erosion ion Cl- in the process of polarization. Combined with polarization properties, the optimal ratio of multi-scale carbon / cement composite anode material is determined to be CF03CNT15CB2,. The stable period of anode material with CF03CNT15CB2, content is over 200h under the extreme environment of 1200mA/m2 polarization current and PH value of 13.5. Secondly, by analyzing the Laplace equation of electric field in ICCP system and the principle of secondary current interface of COMSOL corrosion module, the COMSOL numerical simulation method of electric field in ICCP system is established. The measured anodic polarization curve and the cathodic polarization curve under complex corrosion state were loaded at the electrode reaction interface. The numerical calculation model of ICCP electric field was established by using the free tetrahedron mesh and the COMSOL steady-state solver. The surface potential, current density and electric field distribution of concrete were analyzed by COMSOL program. The results show that the electric field of concrete near the cathode and anode is the strongest, while the current density of the steel / concrete interface is the largest. The ICCP system can effectively protect the steel bar by using the anode material laid near the local area of the steel bar surface. Finally, according to the established COMSOL numerical model of ICCP corrosion control system, combined with the multi-scale carbon / cement composite anode material, the prototype system of T-beam and hollow cylindrical ICCP corrosion control system is built. The surface potential of steel bar is simulated and compared with the test results. The results show that the relative error is less than 20% except for some measuring points on T-beam. The reliability of COMSOL numerical model of ICCP corrosion control system is verified by experiments. In addition, according to the protection potential criterion and 100mV polarization attenuation criterion in the European and American cathodic protection standards, the corrosion effect of the steel bar in the ICCP system was evaluated by measuring the half-cell potential on the steel bar surface and the polarization attenuation value for 20 hours. The results show that the optimum design of ICCP corrosion control electric field can protect the corrosion of typical components such as T-beam and hollow cylinder reasonably, and the multi-scale carbon / cement composite anode material can be used in engineering practice.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU375
[Abstract]:The corrosion of steel bar is the main reason to reduce the durability of reinforced concrete structure. Cathodic protection (Cathodic Protection,CP) is the only effective way to directly prevent the corrosion of steel concrete structure. The key to ensure the accuracy and reliability of (Impressed Current Cathodic Protection,ICCP) system lies in the development of high efficiency durable anode material and the accurate simulation of electric field in ICCP system. In this paper, multi-scale carbon / cement composite anode materials were prepared by theoretical study, numerical simulation and experimental verification, and the electric field of ICCP was systematically studied. Firstly, the conductive properties of carbon fiber, carbon black and carbon nanotube cement composites were analyzed. According to its conductive mechanism, the multi-scale carbon / cement composite anode materials were prepared according to its conductive mechanism, economy and constructability. The polarization resistance of multi-scale carbon / cement composite anode materials was studied by accelerated polarization test, and the polarization mechanism of the anode materials was analyzed by SEM,EDS et al. The results show that the polarization process of the anode material consists of three stages. The polarization potential of the anode material increases slowly in the first two stages due to the increase of the moisture content of the cement matrix and the formation of the antielectric field inside the anode material. In the third stage, the polarization potential of the sample increases sharply due to the oxidation of carbon fiber, and the stable period of the first two stages is the effective service period of the anode material. In addition, the multi-scale carbon / cement composite anode material has anti-interference to the erosion ion Cl- in the process of polarization. Combined with polarization properties, the optimal ratio of multi-scale carbon / cement composite anode material is determined to be CF03CNT15CB2,. The stable period of anode material with CF03CNT15CB2, content is over 200h under the extreme environment of 1200mA/m2 polarization current and PH value of 13.5. Secondly, by analyzing the Laplace equation of electric field in ICCP system and the principle of secondary current interface of COMSOL corrosion module, the COMSOL numerical simulation method of electric field in ICCP system is established. The measured anodic polarization curve and the cathodic polarization curve under complex corrosion state were loaded at the electrode reaction interface. The numerical calculation model of ICCP electric field was established by using the free tetrahedron mesh and the COMSOL steady-state solver. The surface potential, current density and electric field distribution of concrete were analyzed by COMSOL program. The results show that the electric field of concrete near the cathode and anode is the strongest, while the current density of the steel / concrete interface is the largest. The ICCP system can effectively protect the steel bar by using the anode material laid near the local area of the steel bar surface. Finally, according to the established COMSOL numerical model of ICCP corrosion control system, combined with the multi-scale carbon / cement composite anode material, the prototype system of T-beam and hollow cylindrical ICCP corrosion control system is built. The surface potential of steel bar is simulated and compared with the test results. The results show that the relative error is less than 20% except for some measuring points on T-beam. The reliability of COMSOL numerical model of ICCP corrosion control system is verified by experiments. In addition, according to the protection potential criterion and 100mV polarization attenuation criterion in the European and American cathodic protection standards, the corrosion effect of the steel bar in the ICCP system was evaluated by measuring the half-cell potential on the steel bar surface and the polarization attenuation value for 20 hours. The results show that the optimum design of ICCP corrosion control electric field can protect the corrosion of typical components such as T-beam and hollow cylinder reasonably, and the multi-scale carbon / cement composite anode material can be used in engineering practice.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU375
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