亚硝酸盐在既有混凝土结构中阻锈作用研究

This research proposes a new method to inhibit rebar corrosion for existing reinforced concrete structures. In this method, the nitrite ions are provided for the existing reinforced concrete structure which is experiencing corrosion or in a corrosion environment due to the chloride ions or carbonation. The concentration of nitrite ion surrounding the rebars is raised to the corrosion resistant threshold value to protect the rebars. First, the project will examine the methods of supplying nitrite ions for the existing reinforced concrete structures and the effects of uneven nitrite ions concentration on macro corrosion of rebars. Then this project will study the influence of concrete strength, carbonation, temperature, humidity and admixtures on nitrite ion diffusion coefficient, and interpret the diffusion of nitrite ions and the mechanism of corrosion inhibition in terms of multiple factors. A nitrite ion diffusion model will be proposed, which will be examined and improved by analyzing the relationship between diffusion model and the measured concentration of nitrite ions. The model will be used to predict the duration of protective effect of the nitrite ions with the effective threshold concentration on the surface of rebar. The objective of this study is to inhibit rebar's corrosion by forming a passivative environment on it's surface without damaging the concrete cover, and the study will provide theoretical foundation and technical support to prolong the service life of reinforced concrete structures.

本项目拟提出既有混凝土结构钢筋阻锈的新方法，即碳化和氯盐作用下正在腐蚀或处于腐蚀环境的既有混凝土结构内钢筋表面供给亚硝酸根离子，使其表面亚硝酸根离子浓度达到可抑制腐蚀的临界浓度。本项目首先研究既有混凝土结构内亚硝酸根离子的供给方法、钢筋表面亚硝酸根离子浓度不均匀时浓度差对宏电池腐蚀的影响。此基础上进一步研究混凝土强度、碳化、温湿度和掺合料等关键因素对亚硝酸根离子扩散系数的影响，阐明亚硝酸根离子在多因素作用下扩散规律及阻锈机理，建立亚硝酸根离子扩散的广义理论模型，结合实际工程分析扩散模型与实测浓度之间的相关关系，验证和完善多因素作用下扩散理论模型，预测钢筋表面保持有效亚硝酸根离子临界浓度的阻锈年限，从而提出利用亚硝酸盐抑制既有混凝土结构钢筋腐蚀的新理论及新方法。本项目旨在不破坏混凝土保护层的前提下使钢筋表面形成致钝环境，抑制钢筋腐蚀，为提高钢筋混凝土结构的使用寿命提供理论依据和技术支持。

本项目提出既有混凝土结构钢筋阻锈的新方法，即碳化和氯盐作用下正在腐蚀或处于腐蚀环境的既有混凝土结构内钢筋表面供给亚硝酸根离子，使其表面亚硝酸根离子浓度达到可抑制腐蚀的临界浓度。本项目首先研究了既有混凝土结构内亚硝酸根离子的供给方法、钢筋表面亚硝酸根离子浓度不均匀时浓度差对宏电池腐蚀的影响。此基础上根据Fick第二定律建立混凝土表面涂刷亚硝酸钙水溶液时亚硝酸根离子在混凝土中扩散模型以保护混凝土中钢筋，并用实验验证该模型的合理性。同时依据亚硝酸根离子扩散模型预测亚硝酸根离子保护钢筋的年限，阐明亚硝酸根离子在多因素作用下扩散规律及阻锈机理，建立亚硝酸根离子扩散的广义理论模型，结合实际工程分析扩散模型与实测浓度之间的相关关系，验证和完善多因素作用下扩散理论模型，预测钢筋表面保持有效亚硝酸根离子临界浓度的阻锈年限，从而提出利用亚硝酸盐抑制既有混凝土结构钢筋腐蚀的新理论及新方法。本项目旨在不破坏混凝土保护层的前提下使钢筋表面形成致钝环境，抑制钢筋腐蚀，为提高钢筋混凝土结构的使用寿命提供理论依据和技术支持。