基于水泥基凝胶体系柔性化的钢桥面铺装材料的研发及其改性机理研究

Steel deck pavement is one of the key points for large span steel bridge construction. The difficulties for pavement are frequent vibration of deck and large-range fluctuation of service temperature. Generally, modified asphalts have often been adopted for steel deck pavement. In this field, cementitious materials have seldom been used as cementitious matrix belongs to brittle matrix which is hard to meet the requirements of vibrating steel deck. Recently, some ductile cementitious matrix has been studied and produced. With the development of cementitious matrix modification, this study is designed to incorporate the fibers into the ductile cementitious matrix to obtain a reinforced true ductile cementitious material. The materials can present excellent ductility and fatigue resistance without occurrence of micro cracks which is necessary to the steel deck pavement. Furthermore, the mechanisms of “cementitious matrix modification” and “incorporation of ductile matrix and fibers” are to study. The reinforced true ductile cementitious materials will become a new material choice for pavement. This study is going to use thermosetting epoxy and coupling agent to modify cementitious matrix chemically implanting organic molecules onto cementitious silicates. By the advanced technology, e.g. solid NMR, XRD, and TEM, this study is to investigate interaction between organic modifiers and cementitious matrix. With tests of impermeability test, shearing tests, poll-out tests and etc, the adhesiveness can be characterized. With CT scanning, the occurrence and development of fatigue cracks can be quantified.

钢桥面铺装是大跨径钢桥建设的关键性难题之一，其主要困难在于铺装材料难以同时适用于高频大振幅振动及超宽的正负温度域使用环境。以水泥基为基体的材料由于基体本身所显现出的脆性特点，因此，通常水泥基材料很难被钢桥面铺装所接受。本项目通过添加热固性树脂及硅烷偶联剂等改性材料改变水泥基凝胶体系的分子结构，在分子层面上深度提高水泥基体的柔韧性，结合纤维增强技术，研究在无裂纹出现的前提下大幅提高水泥基材料的柔韧性、延性及抗疲劳性能，实现水泥基材料的柔性化。采用固体核磁共振仪、X射线衍射分析仪、透射电镜等手段，揭示课题所设计的热固性树脂体系与水泥水化的相互作用机理。利用抗渗、剪切及拉拔试验、约束试件温度应力及干缩试验等，研究柔性水泥基材料与钢桥面板的粘结性等使用性能及其无缝化技术。采用CT扫描技术，量化研究疲劳裂纹的萌生及扩展。研究成果为丰富我国乃至世界范围的柔性水泥基钢桥面铺装技术提供理论依据。

钢桥面铺装是大跨径钢桥建设的关键性难题之一，其主要困难在于铺装材料难以同时适用于高频大振幅振动及超宽的正负温度域使用环境。以水泥基为基体的材料由于基体本身所显现出的脆性特点，因此，通常水泥基材料很难被钢桥面铺装所接受。本项目通过添加热固性树脂及硅烷偶联剂等改性材料改变水泥基凝胶体系的分子结构，在减少裂纹的前提下提高了体系的柔韧性。结合纤维增强技术，研究在无裂纹出现的前提下大幅提高水泥基材料的柔韧性、延性及抗疲劳性能，实现水泥基材料的柔性化。（1）采用国产PVA纤维、石英砂、硅酸盐水泥、粉煤灰、高效减水剂等原材料，基于微观力学和断裂力学设计原理，探讨微观结构与宏观性能的内在联系，研制了成本较低、延性性能良好的大掺量粉煤灰ECC 材料。（2）采用商业有限元软件ANSYS建立三维有限元模型，计算分析各种工况下钢桥面铺装体系的力学响应，把握胶接界面应力状态，探究了铺装体系层设计控制指标与铺装体系材料参数及结构参数之间的内在联系。（3）对于湿法粘结，胶粘剂与 ECC 各自的固化及强度形成过程中存在水分且彼此相互影响，界面性能难以保证。采用拉拔、单剪和斜剪等大量室内试验评价湿法粘结的界面粘结性能，同时探讨冻融和湿热作用下的界面粘结性能衰减规律，并建立了湿法粘结界面抗剪强度准则。（4）采用双悬臂梁（DCB）试件和末端切口四点弯曲梁（4ENF）试件分别进行I型、II型断裂试验，采用虚拟裂纹闭合技术计算临界能量释放率；基于Workbench计算平台建立三维双向流固耦合模型，分析荷载作用下界面含水裂纹内的动水压力作用，探究了含水界面裂纹的扩展机理。（5）采用固体核磁共振、XRD、压汞试验等手段，研究了热固性树脂体系与水泥水化的相互作用机理。试验研究了柔性水泥基材料的典型配比及其使用性能，特别是该材料疲劳裂纹的萌生及扩展。