混凝土硫酸盐侵蚀下的干湿循环制度及其损伤机理研究

According to lack of common views and theory proofs for the dry-wet circulation system of hydraulic concrete structure in aggressive environment, the mechanical degradation experiments of concrete attacked by sulfate will be performed under the influence of different kinds of the dry-wet circulation. The experiment selects the dry-wet parameters including time ratio of dry to wet, dry-wet period and drying way as the principal control variables. The evaluation indicators are dynamic modulus of elasticity, volume deformation and flexural strength. The formulas of degradation properties of concrete will be deduced varying with the dry-wet cycle parameters. The erosion contributions of sulfate in concrete will be analyzed and quantified respectively resulted from physical crystallization and chemical reaction by means of modern testing techniques. The transport and reaction mechanism of sulfate in damaged concrete will be revealed. The corresponding quantitative relationship between the micro-structure damage characterization parameters and macro-property evaluation indicators of erosion concrete will be developed. Based on concrete mesomechanics and damage mechanics theories, the degradation mechanism will be revealed and the transport-reaction-damage model will be established for concrete attacked by sulfate under the different dry-wet circulation regime. Furtherly, the most unfavorite dry-wet cycle parameters will be determined and the desirable dry-wet cycle regimes will be proposed for the laboratory accelerated test. The expected research results will support the developing of unified dry-wet circulation standard and improve the test study system of concrete against sulfate, which will promote further research on the durability of concrete in aggressive environment.

本项目针对侵蚀环境下水工混凝土结构干湿循环试验制度尚未达成共识、缺乏理论依据的现状，以硫酸盐侵蚀为劣化方式，以干湿比、干湿循环周期和干燥方式等干湿循环参数为控制变量，以动弹性模量、体积变形和弯曲强度为评价指标，进行不同干湿循环制度影响下混凝土硫酸盐侵蚀的力学性能试验，建立基于干湿循环参数的混凝土性能劣化计算公式；通过现代测试技术分析并量化混凝土中硫酸盐物理结晶与化学反应的侵蚀贡献，揭示干湿循环制度下硫酸盐的传输反应机制；运用混凝土细观力学和损伤力学理论，量化混凝土微观结构表征参数与宏观性能评价指标之间的对应关系，揭示硫酸盐侵蚀下干湿循环制度对混凝土的损伤机理，构建干湿循环条件下混凝土硫酸盐侵蚀的传输-反应-损伤模型，从而确定最不利干湿循环参数，提出适用于实验室加速试验的干湿循环制度。项目预期成果将为统一的干湿循环制度标准的制定提供依据，推动侵蚀环境下混凝土耐久性研究的聚焦深入发展。

本项目针对现有水工混凝土结构干湿循环试验制度尚未形成共识并缺乏理论依据的现状，通过控制干湿比干湿循环周期和干燥方式等干湿循环参数，进行不同干湿循环制度影响下混凝土硫酸盐侵蚀的力学性能试验，以动弹性模量、体积变形和弯曲强度为依据建构建了干湿循环参数与混凝土宏观力学性能之间的相关关系；通过微观测试技术分析并量化了混凝土中物里硫酸盐与化学硫酸盐的比例，从而揭示了干湿循环制度下硫酸盐的传输反应机制；基于孔结构分形特征，建立了干湿循环条件下硫酸根多尺度传输模型。项目成果将为统一的干湿循环制度标准的制定提供参考依据，推动干湿循环环境下混凝土耐久性研究的深入发展，指导干湿循环与硫酸盐耦合条件下混凝土耐久性设计与修复。