滨海环境下高耐久性低胶凝自密实混凝土材料设计及应用基础研究

自密实混凝土是现代土木工程常用的建筑材料之一，但其较高胶凝材料导致较高碳排放。为满足我国滨海基础设施大规模建设及可持续发展需求，设计高耐久性的低胶凝（特别是低水泥）用量自密实混凝土（LB-SCC）具有重要现实意义。本项目基于对颗粒堆积理论及强度-耐久性双指标设计方法的优化修正，建立一般使用环境下LB-SCC材料设计准则；在此基础上，系统研究滨海环境下LB-SCC耐久性关键问题，揭示其劣化机理，建立多场多尺度劣化预测模型；同时，基于混凝土材料孔隙、裂缝等微观结构劣化与混凝土中钢筋锈蚀问题之间相互交织、循环退化的逻辑分析，提出混凝土性能提升及钢筋锈蚀抑制联合技术，共同建立滨海环境下以材料劣化抑制为目的的LB-SCC耐久性集成提升策略；最后，构建滨海环境下LB-SCC结构的耐久性综合评价体系。本项目的创新研究成果对推动滨海环境下具有高耐久性的混凝土结构的工程应用具有重要科研及实践价值。

Self-compacting concrete (SCC) is a widely used building material in modern Civil Engineering. However, the high binder content required in the mix proportioning of traditional SCC will cause additional carbon emissions. In order to meet the needs of large-scale construction and sustainable development of coastal infrastructure in China, it is of great practical significance to design high-durability, low-binder (especially low-cement) self-compacting concrete (LB-SCC). This project, based on the optimization and modification of the particle compacting theory and the strength-durability dual index design method, aims to establish a material design method for LB-SCC used in general environment; The key durability issues of LB-SCC especially in costal environment will be discussed and the major degradation mechanisms will be revealed systematically. Then a multi-scale and multi-filed transport model will be established for predicting the ingress speed of corrosive species from the environment; In the meantime, based on the logic analysis of the interweaving and cyclic degradation between the deterioration of the concrete microstructure such as pores and cracks and the corrosion of reinforcing steel, a joint technology of concrete performance improvement and corrosion suppression is proposed. Then a comprehensive durability improvement strategy for LB-SCC aimed for material degradation suppression in coastal environment is established; Finally, a comprehensive evaluation system for the durability of LB-SCC structures in the coastal environment will be established. The innovative research results of this project are of great significance and value to enrich and develop the basic theory of high-performance LB-SCC material design, and promote the engineering application of high-durability LB-SCC structures in the coastal environment.