The application of stress wave techniques to evaluation of near-surface degradation of concrete

• Main Authors: Syue-Jhen You, 游雪禎
• Other Authors: Yi-ching Lin
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/91693217760729831623

碩士 === 國立中興大學 === 土木工程學系所 === 100 === Concrete is the most popular material used in the construction industry because of the following features: resistance to high temperature, high load-carrying capability, easy modeling, relatively low cost. However, the durability of concrete will be dramatically reduced when concrete structures are subjected to fire or the penetration of aggressive materials, such as sulfates, carbon dioxide, and chloride ions. Therefore, the use of non-destructive testing to assess the current deterioration degree of concrete can achieve the purpose of early warning. In this study, the stress wave method is used to measure the surface wave velocity of concrete plates exposed to high temperature in order to assess the concrete deterioration. In addition, the surface wave velocity technique is also adopted to evaluate the deterioration of concrete specimens immersed in sulfate solution. Experimental results show that for the case of concrete plate subjected to high temperature the R-wave speed increases with the increasing distance away from impact, and the R-wave speeds vary according to different wavelengths. Thus, the extent of damage according to the variation in the R-wave speed due to different measurement distances can be found. For the case of concrete specimens subjected to sulfate attack, the surface is soft and the eroded depth is very shallow. As a result, the wave velocity measurement results did not differ much while the wavelengths of the R-wave introduced by the current test method are much larger than the eroded depth of the specimens.