新型硅烷/氧化石墨烯涂层对海工混凝土表层强化机制及损伤劣化机理研究

Strengthen and anti-corrosion treatment of concrete surface is the crucial issue to ensuring the safety and durability of engineering facility in marine environment. By now, silane was used to protect concrete frequently because its excellent hydrophobic property. Nowadays, it’s believed that graphene oxide (GO) can increase the mechanical property of cement materials by optimizing their microstructure. Based on the above theory, silane/GO composite will has been prepared by sol-gel process firstly. The reaction mechanism between silane and GO will be studied deeply. And then, the silane/GO coating will has been structured in concrete surface layer through optimization the molecular structure of silane/GO composite. The formation process of the silane/GO coating in the surface layer of concrete will be studied by FTIR, AFM, ESEM, et al. The interaction mechanism between the silane/GO coating and concrete surface will be assessed, so as to realize the controllable regulate on chemical composition and microstructure of concrete surface. At the same time, the synergism mechanism between silane and graphene on increase the durability properties of concrete will be explored. Furthermore, the effect of silane/graphene coating on the microstructure of the concrete surface layer in corrosion process in marine environment will be studied deeply. The quantitative relationships between the concrete surface microstructure and the durability properties of the concrete will be proposed. From the above studies, the damage and deterioration of concrete with silane/GO coating experiencing fatigue load and environmental effect will have been researched. Moreover, we will establish a assessment system about the durability process of concrete structure protected by silane/GO coating in marine environment.

海工混凝土表层的防腐与强化是保证海洋工程设施耐久性和安全性的关键问题。本项目基于硅烷优良的渗透防水性能和氧化石墨烯改善水泥基材料微观结构的特点，从低表面能化学组成和表层微观结构强化设计出发，通过溶胶-凝胶法合成硅烷/氧化石墨烯复合材料，并研究两者的反应机理。通过优化硅烷/氧化石墨烯复合材料的分子组成与结构，在混凝土表层构建硅烷/氧化石墨烯涂层，探索其反应过程与构建机理。针对海洋环境，研究硅烷和氧化石墨烯提升混凝土耐久性能的协同作用机理，探索硅烷/氧化石墨烯涂层对混凝土腐蚀过程中表层微结构的影响，提出表层微结构与耐久性的定量关系，并建立涂层对混凝土表层的强化机制。在此基础上，明确在荷载和海洋环境耦合作用下，硅烷/氧化石墨烯涂层对混凝土损伤劣化过程的影响机理，最终建立基于涂层作用下的混凝土结构耐久性评估体系，为保障海工混凝土结构安全及长寿命运行提供理论依据与技术支撑。

海工混凝土表层的防腐与强化是保证海洋工程设施耐久性和安全性的关键问题。本项目基于硅烷优良的渗透防水性能和氧化石墨烯改善水泥基材料微观结构的特点，通过溶胶-凝胶法合成硅烷/氧化石墨烯复合材料（GS），从混凝土表面化学组成与微观结构设计出发，在其表面构建硅烷/氧化石墨烯超疏水涂层，首先研究了该涂层在实验室环境下对混凝土耐久性的影响；再针对实际海洋环境，研究了该涂层在荷载与环境耦合作用下对混凝土耐久性的影响，建立荷载与GS作用下氯离子传输模型；最后研究了GS对开裂水泥基材料抗氯离子渗透效果以及对水泥基材料抗裂和抗收缩效果的影响，提出GS作用下的混凝土结构耐久性综合评价体系。研究结果表明，（1）异丁基三乙氧基硅烷（IBTS）可以与氧化石墨烯（GO）合成出性质稳定的复合材料，且在混凝土表面形成防水效果良好的疏水涂层，渗透深度超过9mm，静态接触角超过120°；（2）GS能够有效提升混凝土防水效果90%以上，即使在磨损和开裂后的混凝土表面依然具有良好的防水性能；（3）GS可以有效抑制氯离子在混凝土中的扩散，随着荷载水平的增大，GS的防护效果仍能达到一个较高水平，即使当荷载水平提高到50%时，氯离子含量比未涂覆时降低40%；（4）在相同荷载水平下，GS还能有效地减少硫酸根离子在混凝土中的迁移与扩散，同时也降低了硫酸根离子的反应系数，说明其抑制了硫酸根离子与混凝土之间的反应，提高了混凝土抗硫酸盐侵蚀的能力；（5）GS对于氯离子沿水泥基材料裂缝扩散的抑制作用较好，在裂缝处涂覆GS后，钢筋容抗弧的收缩减小，当裂缝宽度达到0.5mm时，GS仍然可以有效地抑制氯离子的扩散。（6）GS的涂覆能够提升混凝土3~4个抗裂等级，而且GS对混凝土收缩开裂抑制效果最佳，初始裂纹出现时间为13.5天，相比未涂覆增大130%以上。本项目为提升我国海洋环境下混凝土的耐久性，增强混凝土安全使用系数，降低工程后续维护成本提供了一定的理论基础与技术参考。