Long-term durability of Carbon CFRP Composites applied to R/C Concrete Bridges

调查将集中在监测和分析犹他州盐湖城的州街桥，该桥已经用碳FRP复合材料进行了抗震改造。恶劣的天气变化，冬季盐的使用，以及冻结和融化的模式使这成为一项独特的研究。测试项目、板和钢瓶将被放置在桥址，并在预定的时间间隔内用于破坏性测试。进一步的实验室测试，将调查单变量和双变量。本研究的目的是：(a)评估由于温度、碱度、氯化物、紫外线照射和冻融循环的变化，碳- CFRP复合材料的强度和弹性模量的长期降低；(b)通过机械、热和化学测试评估CFRP复合材料与混凝土之间粘结的耐久性；(c)评估CFRP复合材料改造对钢筋混凝土桥梁强度和结构特性的长期影响；(d)根据从州立街大桥的长期监测中收集的资料，制订“耐久性降低系数”，用于设计碳纤维增强塑料复合材料改造。在拟议的耐久性研究中，将使用碳纤维和树脂的基质，而不是只测试商业产品。总共将调查五种复合材料：三种商业复合材料产品将由三家独立制造商提供，两种非商业产品。

The investigation will focus on the monitoring and analysis of the State Street Bridge in Salt Lake City, Utah, which has been seismically retrofitted with Carbon FRP composites. The severe weather changes, the application of salt in the winter, and the freezing and thawing patterns make this a unique study. Test items, plates, and cylinders will be placed at the bridge site and used for destructive testing at predetermined intervals. Further laboratory testing, will investigate single and dual variables. The objectives of this research are to: (a) evaluate the long-term reduction in strength and modulus of elasticity of the carbon CFRP composite due to changes in temperature, alkalinity, chlorides, UV exposure, and freeze/thaw cycles; (b) evaluate the durability of the bond between the CFRP composite and concrete using mechanical, thermal, and chemical testing; (c) evaluate the long-term effect of the CFRP composite retrofit on the strength and structural characteristics of the reinforced concrete bridge; (d) develop a "durability reduction factor" to be used in the design of a CFRP composite retrofit, based on the information gathered from the long-term monitoring of State Street Bridge. Instead of testing only commercial products in the proposed durability study, a matrix of carbon fibers and resins will be utilized. A total of five composite materials will be investigated: three commercial composite products, to be supplied from three independent manufacturers and two non-commercial products.