风蚀区冻融-盐蚀作用下风积沙混凝土耐久性响应机制研究

According to the characteristics of the resources distribution and the harsh environment faced by concrete structure material in the western region of Inner Mongolia Yellow River basin, Under the deeply consideration of the mechanism of the durability of concrete under the action of wind-sand erosion，freezing-thawing and salt corrosion, making full use of the enrichment aeolian sand resources of Inner Mongolia, configuring aeolian sand concrete and carrying out relevant experiment, developing excellent wind abrasion resistance, freeze resistance and salt corrosion resistance characteristics of aeolian sand concrete as a new type of green environmental protection concrete material. Draw lessons from existing research results, analyzing the microscopic mechanical properties and micro-pore structure of interface transition zone, cement paste and coarse aggregate from the micro level, revealing the internal forming mechanism of the aeolian sand concrete, quantitative description the influence mechanism between microscopic characteristics and macro performance; With the aid of modern testing technology, revealing the inner microstructure characteristic parameters of the aeolian sand concrete in harsh natural environment (wind-sand abrasion, freezing-thawing snd salt corrosion coupling action) from micro level, discussing the engineering properties and durability damage mechanism of aeolian sand concrete, analyzing the damage evolution process mechanics and establish durability damage prediction model of aeolian sand concrete. It will not only provide a theoretical basis and scientific parameters for the durability design of aeolian sand concrete in the cold wind erosion area, but also make a useful attempt to develop a new type of green, environmental protection, durable concrete materials in the western Inner Mongolia.

针对内蒙古黄河流域地区资源环境分布特点和混凝土结构材料所面临的严酷环境，充分利用内蒙古西部地区富集的风积沙资源，配置风积沙混凝土并进行相关试验，深入考虑风沙吹蚀与冻融-盐蚀耦合作用下水工混凝土的耐久性响应机制。借鉴已有研究成果，从微观层面对混凝土界面过渡区、水泥浆体、粗骨料三相的微观力学特性和微观孔隙结构进行分析，揭示风积沙混凝土形成机理，定量描述微观特性与宏观性能之间的内在作用机制与影响机理；借助现代测试技术手段，从微观层面揭示风积沙混凝土高寒风蚀区受严酷自然环境（吹蚀-冻融-盐蚀）影响的内部微观孔隙结构特征参数的动态演变规律，探讨风沙吹蚀与冻融-盐蚀耦合作用下风积沙混凝土的工程特性和耐久性响应机制，对风积沙混凝土耐久性损伤演化全过程进行分析，并建立其耐久性随机损伤预测模型，为高寒风蚀区风积沙混凝土耐久性设计提供理论依据和科学参数，为发展绿色、环保、耐久的新型混凝土材料做出有益尝试。

（1）利用内蒙古沙漠地区风积沙作为细骨料，以腾格里沙漠、乌兰布和沙漠、库布其沙漠3种沙源地风积沙理化性质为变量，根据“灰色理论”将风积沙细度模数MX分为三类：A类，MX＜0.6；B类，0.6≤MX＜0.7；C类，MX≥0.7；A类风积沙混凝土强度最低，C类风积沙混凝土强度最高且与普通混凝土强度相近。.研究了风沙吹蚀对风积沙混凝土的影响，在整个风沙吹蚀过程中，吹蚀坑对风积沙混凝土的损伤程度要明显大于吹蚀沟壑，造成风积沙混凝土吹蚀破坏的主要因素是垂直于吹蚀面的法向应力。风沙吹蚀可起到“催化”效应，加速冻融作用下混凝土内部微裂纹产生和发育，风沙吹蚀影响下冻融循环内部损伤大于单纯冻融循环。.（2）以沙漠沙资源为原材料，开发新型非金属矿物粉体—风积沙粉体，激发其活性，研制了风积沙粉体混凝土，并对其在高寒、高盐、多风、碳化环境下的劣化机理及耐久性能进行探讨。利用纳米压痕仪确定风积沙粉体混凝土界面过渡区中水化产物的分布及其经过冻融循环试验前后的变化规律。建立了风积沙粉体混凝土的服役寿命预测模型。利用纳米压痕试压确定风积沙混凝土界面过渡区中水化产物的分布及其经过冻融循环试验前后的变化：冻融前水化产物主要以HD C-S-H凝胶为主，冻融后以LD C-S-H凝胶为主，CH晶体明显减少，界面过渡区中HD C-S-H凝胶决定着风积沙混凝土的耐久性，而CH的含量影响着HD C-S-H凝胶的稳定性，界面过渡区中两者的含量对风积沙混凝土耐久性的影响最大。.（3）充分利用内蒙古风积沙和浮石等自然资源，研究配制新型的绿色环保混凝土——风积沙轻骨料混凝土，综合考虑冻融、硫酸盐侵蚀、低温等多种不利因素影响，从宏观性能劣化规律、孔隙水冰相变机制、微观孔隙结构特征以及孔隙三维结构动态发育等方面，探究冻融盐蚀环境下风积沙轻骨料混凝土抗冻性能损伤劣化机理。