新疆盐渍地区碳硫硅钙石的形成及其对混凝土结构损伤机制研究

In Xinjiang area,mostly for the cold and saline region,effect of chemical attack,salt crystallization,stress attack,which made erosion pace in reinforced concrete significantly higher than in other regions. In many corrosion reaction,Thaumasite form of sulfate attack (TSA) directly destroys the main binding phase calcium-silicate-hydrate (C-S-H) in hardened cement.Cement matrixes are converted into mush from the surface inwards.The properities of cement-based materials and concrete structure durability are strongly influenced by TSA..Concrete under corrosive service life prediction model for a lot of but mainly focus on chloride ion diffusion, corrosion and carbonation. Established, and from the point of view of the damage mechanism of research these factors caused by the evolution of damage in concrete, establishment of corrosion of concrete damage evolution model research is less. For responsiveness to TSA, combined with the environmental characteristics of the saline area of Xinjiang, the mixing method accelerated thaumasite formation, using FTIR, ICP/IC,XRD/Rietveld means different corrosion time the generated carbon sulfur silicon calcium stone set characterization, and to the definition of the mechanical properties of concrete damage degree, the establishment of water binder ratio, concentration of corrosion, corrosion time, the rate of the reaction, the reaction degree of and stress level and loss between the degree of function, based on damage failure criterion establishment of corrosion damage of concrete evolution equation, the concrete durability assessment and design to provide theoretical reference.

新疆地区大多为严寒盐渍地区，混凝土中化学腐蚀、盐结晶腐蚀和应力腐蚀造成混凝土劣化速率显著高于其他地区。在众多腐蚀反应中，碳硫硅钙石反应(TSA)在低温下消耗C-S-H凝胶，使得混凝土强度降低甚至崩溃，其危害性较传统硫酸盐腐蚀更为严重。混凝土在腐蚀作用下服役寿命预测模型很多，但主要围绕氯离子扩散、钢筋锈蚀和碳化等方面建立的，而从损伤机制角度研究这些因素造成混凝土材料损伤的演化规律，建立腐蚀作用凝土损伤演化模型的研究较少。针对TSA反应，结合新疆盐渍地区环境特点，本项目通过内掺法加速碳硫硅钙石的形成，使用FTIR、ICP/IC、XRD等手段对不同腐蚀时间所生成的碳硫硅钙石定量表征，并以混凝土力学性能定义损伤度，建立水胶比、腐蚀离子浓度、腐蚀时间、反应速率、反应程度以及应力水平与损失度之间的函数关系，基于损伤破坏准则建立腐蚀损伤过程中混凝土演化方程，为混凝土材料耐久性评估与设计提供理论参考。

新疆盐渍地区混凝土材料因低温碳硫硅钙石型硫酸盐侵蚀反应（Thaumasite Sulfate Attack，TSA），造成混凝土结构服役寿命难以达到实际设计值。由于TSA在消耗C-S-H凝胶过程中几乎不产生宏观可见变化，并且其晶体结构与钙矾石极为相似，使得TSA具有很强的隐蔽性，导致实际工程中难以准确判定侵蚀类型而无法采取适宜的防范措施，这给新疆盐渍地区基础设施的耐久性和安全运营带来巨大的安全隐患。.本项目采用选择性化学消除钙矾石，再利用XRD-Rietveld法较好解决了碳硫硅钙石的定量分析困扰；研究过程系统研究了内源性和外源性硫酸盐和碳酸盐种类和掺量、不同浓度的复盐、水胶比、温度以及不同浸泡方式等因素在低温环境下发生TSA后对混凝土材料和结构所造成的损伤机制。通过热力学分析，建立发生TSA反应的热力学模型，结合TSA的定量分析探究各因素对硫酸盐侵蚀产物的影响以及侵蚀物相的演变规律。通过碳硫硅钙石反应动力学计算，获取不同体系中TSA综合表观速率以及表观反应活化能。结合TSA反应对水泥基材料力学性能的影响和碳硫硅钙石定量分析结果，推导由TSA反应造成的水泥基材料损伤破坏的损伤因子，建立水泥基材料TSA损伤本构模型，与塑性损伤本构模型作对比，探讨TSA反应对混凝土结构的损伤劣化规律。