Durability study on reinforced concrete axial members retrofitted with fibre-reinforced cementitious matrix (FRCM)**********

纤维增强水泥基复合材料(FRCM)是近年来发展起来的一种加固加固钢筋混凝土结构的加固体系。FRCM由一层或多层防腐纺织品组成，这些纺织品由碳、玻璃或聚对苯撑苯并双恶唑(PBO)格栅制成，这些格栅夹在水泥砂浆层之间。与基于环氧基的纤维增强聚合物不同，FRCM系统中使用的砂浆继承了系统与混凝土基质之间的兼容性，因为这两种材料都以水泥作为共同的“基质”。到目前为止，还没有关于FRCM包裹的RC构件在轴向荷载和恶劣环境条件下的老化性能的数据。拟议的研究旨在通过一系列实验室测试来检验这种性能，这些测试将在钢筋混凝土棱柱和圆柱体上进行，并在轴向荷载下进行测试。测试参数包括试件的横截面(正方形和圆形)、FRCM系统的类型(2种类型)、FRCM层数(1层或2层)、试件包装前的状态(有条件或无条件)以及包装后的暴露条件，其中包括(1)冻融循环、(2)高温、(3)湿度和高温、(4)碱溶液和(5)盐水。未经处理的样本将进行测试，以供参考。将用应变计和/或压力计对试件进行测量，以监测试验过程中的载荷和应变，直到发生故障。在承载力、脱粘、应变、模数和延性方面的试验结果将被记录下来。将根据ACI-549.4R-13的规定确定和验证不同暴露对这些数量的影响。研究结果将被用于制定FRCM系统的概念设计规则，以考虑柱和墙等受压构件中环境老化的影响。

Fabric-reinforced cementitious matrix (FRCM) is a retrofitting system that has been introduced recently to retrofit/strengthen reinforced concrete (RC) structures. FRCM consists of one or more layers of anti-corrosive textiles made of carbon, glass, or Polyparaphenylene benzobisoxazole (PBO) grids that are sandwiched between layers of cementitious mortars. Unlike the epoxy-based fiber-reinforced polymers, mortars used in FRCM systems inherit the compatibility between the system and the concrete substrate since both materials have the cement as a common "base". To date, no data is available on the aging performance of FRCM-wrapped RC elements under the combined effect of axial loading and the exposure to harsh environmental conditions. The proposed research aims at examining such performance through a series of laboratory tests that will be conducted on RC prisms and cylinders wrapped with FRCM and tested under axial loads. The test parameters include the specimen's cross section (square and circular), the type of FRCM systems (2 types), the number of FRCM layers (1 or 2 layers), the specimen's condition prior to wrapping (conditioned or unconditioned), and the exposure condition after wrapping, which include (1) freeze-and-thaw cycles, (2) high temperatures, (3) humidity and high temperatures, (4) alkali solution, and (5) saltwater. Unconditioned specimens will be tested for reference. Specimens will be instrumented with strain gauges and/or compressometers to monitor the loads and strains during the test until failure occurs. Experimental results in terms of capacity, debonding, straining, modulus, and ductility will be recorded. The effect of different exposures on such quantities will be determined and verified against the provisions of ACI-549.4R-13. The results would be used to develop conceptual design rules for FRCM systems, which consider the effect of environmental aging in RC compression members such as columns and walls.