高耐久海工混凝土组成结构设计和关键技术及其应用基础研究

High durability marine concrete is the key material for national ocean strategy. In view of its inherent porous structure), the durability of concrete is urgent to be improved for erosion resistance in harsh marine environment. This project is comprehensively designed in the aspects of surface, interface and matrix of the concrete, to achieve its high durability through regulating the composition and structure of corresponding materials. The main contents are summarized as follows. Firstly, based on the technologies of domestication, cultivation and induction, biology protective coating is designed and going to be studied. The research contents include enrichment incubation of induced bacteria, preferential segregation and induced mechanism for the marine creature. structure-property relationship, durability and regulating mechanism. Secondly, based on the technologies of organic-inorganic composite and nanomaterial regulating, superhydrophobic anti-corrosion coating with double-layer structure is designed and going to be studied. The research contents include structure-property relationship, durability and regulating mechanism. Thirdly, the pre-cladding material and its preparation technology are investigated to enhance ITZ microstructure and sealing harmful ions. And the effect of its composition on ITZ microstructure and chloride sealing mechanism will be respectively illuminated. Fourthly, on the basis of multiple-feedback-circulated design, matching optimizing mechanism between pore size distribution of concrete and particle gradation of ultrafine admixture are systematically discussed to satisfy maximum compactification. Finally, this project is planning to establish damage mechanism and durability model of marine concrete under diversified coupling factors of marine environment. It is expected that these studies could construct and perfect design theory of marine concrete, thus making theoretical foundation for application technology.

高耐久海工混凝土是国家海洋战略迫切需要的关键材料。鉴于混凝土是多相多孔材料，在严酷海洋环境下其耐久性亟待提高。本项目从表面、界面及本体三方面综合设计调控混凝土的组成和结构，实现整体耐久性提升。主要内容：采用驯化培养和诱导技术设计生物防护层，研究诱导细菌的富集培养、选择分离以及对海洋生物的诱导机制；基于有机-无机复合及纳米调控技术设计具有双层结构的超疏水防腐抗渗涂层，研究其构效关系、疏水性、耐久性和调控机制；采用集料预包覆技术强化ITZ结构并固封有害离子，研究纳米改性预包覆材料组成设计、制备技术和对ITZ结构的影响规律及对海砂集料中Cl-的固化机制；采用微纳米超细掺合料颗粒级配多重循环反向设计关键技术，实现孔级配和掺合料颗粒级配的优化匹配，使混凝土达到最大致密化；并研究多因素耦合作用下海工混凝土的损伤机制并建立耐久性模型。为构建和完善高耐久性海工混凝土的设计理论和应用技术奠定基础。

高耐久海工混凝土是国家海洋战略迫切需要的关键材料。鉴于混凝土本征的疏松多孔结构，在严酷海洋环境下其耐久性亟待提高。本项目从表面、界面及本体三方面综合设计调控混凝土的组成和结构，突破了耐久性难以有效提升的瓶颈。聚焦水下浸泡区耐久性提升，采用驯化培养和诱导技术设计生物防护层，通过驯化细菌形成了表面碳酸钙沉淀层，对表面微小裂缝可进行有效地修补防护，并验证了菌株NM-1、XH-1、FX-1的实际应用效果，探明了生物防护层诱导形成机制；为提升海工混凝土浪溅区和大气区耐久性，基于有机-无机复合及纳米调控技术设计了具有双层结构的疏水防腐抗渗涂层，基体层兼具优异的力学性能和耐久性，在此基础上构建的超疏水防腐抗渗涂层接触角可达154°，复合涂层抗氯离子渗透性能大幅提升；为解决海工混凝土ITZ界面空隙偏高和海砂携带氯离子腐蚀钢筋的难题，采用集料预包覆技术强化ITZ结构并固封有害离子，研究纳米改性预包覆材料组成设计、制备技术和对ITZ结构的影响规律及对海砂集料中Cl-的固化机制，磷铝酸盐水泥对海砂的包覆性较好，预包覆粗细骨料混凝土的7d和28d力学性能均高于普通混凝土，且Friedel盐可从30.39%提高至48.36%，具有优良的Cl-固化能力；目标提升混凝土本体致密性，采用微纳米超细掺合料颗粒级配多重循环反向设计关键技术，实现孔级配和掺合料颗粒级配的优化匹配，辅助性胶凝材料（硅灰、矿粉、粉煤灰、纳米SiO2等）二次水化效应既节约成本又可有效提高混凝土结构致密度和耐久性能；基于Cl-固化和阻滞水盐传输的机理，制备了层状双金属氢氧化物(LDHs)和改性硅溶胶(M-CNS)，研究结果表明 LDHs能将Cl-置换至层间或通过结构重构固化Cl-，且2D LDHs薄片能密实水泥基体，改变Cl-传输通道，M-CNS能提高水泥基体致密性，阻滞水盐传输，有效提升混凝土抗Cl-侵蚀性能。最后，研究了海工混凝土的损伤机制并建立了耐久性模型。本项目按计划顺利地完成了预定研究内容和研究目标，可为构建和完善高耐久性海工混凝土的设计理论和应用技术奠定基础。