柠檬酸钠对碱激发粉煤灰滤液中钢筋的阻锈机制  

Inhibition Mechanism of Sodium Citrate on Reinforcing Steel in Extracted Alkali-Activated FlyAsh Solution

作　　者：周霄骋 李曼 施锦杰[1] ZHOU Xiaocheng;LI Man;SHI Jinjie(School of Materials Science and Engineering,Jiangsu Key Laboratory of Construction Materials,Southeast University,Nanjing 211189,China)

机构地区：[1]东南大学材料科学与工程学院,江苏省土木工程材料重点实验室,南京211189

出　　处：《硅酸盐学报》2024年第2期603-613,共11页Journal of The Chinese Ceramic Society

基　　金：国家重点研发计划(2021YFB3802000,2021YFB3802005)。

摘　　要：碱激发粉煤灰是一种兼具低碳与环保优势的建筑材料,具备应用于海洋等氯盐侵蚀环境的潜力。作为一种典型的羧酸盐阻锈剂,柠檬酸钠可进一步保障碱激发粉煤灰中钢筋的耐蚀性。然而,柠檬酸钠对碱激发粉煤灰体系中钢筋的阻锈机制尚未明确。基于此,本研究通过电化学测试、钝化膜表征技术和腐蚀形貌及产物分析方法研究了氯盐侵蚀作用下柠檬酸钠对碱激发粉煤灰滤液中钢筋腐蚀行为的影响,并揭示了其阻锈机制。结果表明:虽然柠檬酸钠会一定程度上影响碱激发粉煤灰体系中钢筋钝化膜的稳定性,但其不仅能与氯离子产生竞争吸附效应,还能在钢筋表面形成吸附膜,从而有效提高钢筋的耐氯盐侵蚀能力。Introduction Alkali-activated fly ash(AAFA)can reduce the carbon emissions from the production of ordinary Portland cement(OPC)by>80%.The utilization of AAFA and the research on the electrochemical behavior of steel in AAFA have thus attracted much attention.Compared with OPC,a higher resistance to chloride-induced corrosion can be achieved in AAFA due to its high alkalinity and zeolite-like adsorption layer.However,the corrosion of steel in AAFA cannot be completely inhibited in harsh environments contaminated with chlorides.Carboxylate groups-based corrosion inhibitors(such as sodium citrate)improve the pore structure and compressive strength of concrete,and have a high inhibition efficiency for steel.Especially at a high chloride concentration,the pitting potential(Epit)of steel treated with carboxylate groups-based corrosion inhibitors is greater than that treated with amine salt and amino acid.Therefore,sodium citrate can be considered as a promising organic corrosion inhibitor to enhance the corrosion resistance of steel in AAFA.However,the inhibition mechanism of sodium citrate for steel in AAFA is still unclear.In this paper,the effect of sodium citrate on the corrosion behavior of reinforcing steel in extracted AAFA solution under chloride attack was investigated by electrochemical measurements and surface characterization techniques,and the inhibition mechanism of sodium citrate was revealed.Methods In this study,the preparation of AAFA solution was carried out at room temperature((25±2)℃).Firstly,a low calcium fly ash was mixed with an alkali-activated solution(80 g/L Na OH solution)at a mass ratio of 1:1,then the mixture was stirred in a closed vessel for 24 h,and finally it was filtered to remove the residues.The concentration of sodium citrate added into the AAFA solution was 100 mmol/L.Conventional ribbed carbon steel(HRB400E)with a diameter of 16 mm was used.The electrochemical measurements,namely electrochemical impedance spectroscopy(EIS)and the cyclic potentiodynamic polarization(CPP),were p

关 键 词：碱激发粉煤灰 钢筋 柠檬酸钠 钝化膜 阻锈机制 

分 类 号：TU503[建筑科学—建筑技术科学]