多因素耦合作用下混凝土中钢筋锈蚀及保护层锈胀开裂机理与模型研究

The reinforcement corrosion of concrete structures with mineral admixtures is the main content in this project. The performances of unti-corrosion and corrosion-induced cover cracking of RC structures with mineral admixtures will be studied under multi-factor coupling action. The corrosion mechanism of reinforcement and the degradation of cover concrete of RC structures with mineral admixtures will be investigated by the combination of laboratory simulation test and field test, experimental test and computer simulation, theoretical model analysis and engineering verification. As the actual structure is in a complex environment, the predicting model of reinforcement corrosion rate in concrete with mineral admixtures will be established considering the factors as RH, temperature, chloride and sulfate content, admixture types, replacement ratio and stress. By considering the sulfate attack of concrete cover, the processes of cover cracking induced both by reinforcement corrosion and sulfate attack will be investigated. The calculation formula of weight loss of reinforcing bar due to corrosion at cover cracking under multi-factor coupling action will also be proposed. Finally, the service life predictions of RC structures with mineral admixtures based on failure criteria of cover cracking will be predicted. The project aimed at promoting the application of concrete with mineral admixtures, which is of great significance to guarantee the sustainable and steady development of the national economy.

本项目以掺合料混凝土结构为对象，以混凝土中钢筋锈蚀为研究主线，系统深入开展多因素耦合作用下混凝土结构抗锈蚀及抗裂性能研究。采用实验室模拟试验与现场试验相结合、模型试验与计算机模拟相结合、理论模型分析与工程验证相结合的研究方法，深入揭示多因素耦合作用下掺合料混凝土结构钢筋锈蚀及保护层混凝土开裂损伤机理。针对实际结构处于复杂环境的特点，全面考虑环境温湿度、氯离子和硫酸根浓度、掺合料种类、掺量、应力水平等因素，建立承载掺合料混凝土中钢筋腐蚀速度预测模型。考虑硫酸盐侵蚀导致保护层混凝土损伤等因素，研究掺合料混凝土保护层在钢筋锈胀力及硫酸盐反应膨胀产物的共同作用下，保护层开裂或者剥落的劣化全过程，建立多因素耦合作用下混凝土结构保护层锈胀开裂条件。基于锈胀开裂寿命准则对掺合料混凝土结构进行寿命预测。本项目立足工程实际，对推广掺合料混凝土结构在复杂环境的应用、保证国民经济可持续发展具有重大的现实意义。

钢筋锈蚀是造成结构性能退化的重要原因之一，实际工程的环境介质常常存在硫酸盐导致混凝土劣化，在钢筋锈蚀和混凝土劣化的同时，结构构性能退化则是多种因素相互作用的结果。本项目以掺合料混凝土为对象，对影响掺合料混凝土结构耐久性的耦合因素进行分析，采用快速试验与现场试验相结合、理论分析与工程验证相结合的研究方法，研究了硫酸盐侵蚀和干湿循环共同作用下掺合料混凝土的劣化损伤规律；考虑硫酸盐侵蚀导致保护层混凝土损伤等因素，研究了掺合料混凝土保护层在钢筋锈胀力及硫酸盐反应膨胀产物的共同作用下，保护层开裂或者剥落的劣化全过程，建立了多因素耦合作用下混凝土保护层锈胀开裂条件。本课题立足工程实际，对于掺合料混凝土结构在复杂环境的推广应用及结构耐久性设计奠定了基础。