Recognition And Analysis Of High-strength Concrete Meso-structure Based On CT Slices

As the acceleration of the scale and speed about the urbanization overworld, the development of modern building needs the performance of concrete more and more strictly. With the advantages of high strength, large carrying capacity, high density, good durability, high-strength concrete has been widely used, but there are also some shortcomings such as high brittleness, burst more easily under high temperatures. To some extent, mixing polypropylene fiber can alleviate the phenomenon of the burst when the high-strength concrete under elevated high temperatures, while there will be more micro-pores, holes inside the concrete when the polypropylene fiber reaches the melting point of160℃, which will ease the internal vapor pressure, thus to some extent, reduce the degradation rate and degree of the HSC at high temperature.. Therefore, the research of the performance of high-strength concrete at mesoscopic level is extraordinary necessary, at the same time, the mesoscopic/microscopic composition and its characteristics of the high-strength concrete have a significant impact on its macroscopic properties, which draws more and more attention and research by the domestic and international scholars.Based on the National Natural Science Foundation of China (Number:51278325) and the Natural Science Foundation of Shanxi Province (Number:2011011024-2), this paper respectively conduct the CT scan test of the high-strength concrete specimens at room temperature and300℃,500℃for1.5h, by contrast of the concrete whether doped with the polypropylene fiber, and finally analyse the internal structure of the high-strength concrete at mesoscopic level. As follows: (1)With the CT scan images of high-strength concrete at room temperature for visual analysis, this part describe the internal composition and its distribution of the specimens, in addition, represent the number, shape and distribution of the initial imperfection such as the micro-holes, porosity.(2)With the CT scan images of high-strength concrete for visual analysis after the specimens under the temperature of300℃,500℃by1.5h, this part describe the shape, quantity and distribution of its internal crack, meanwhile analyse the CT scan images in comparison of the specimens whether doped with the polypropylene fiber.(3)Based on the contrastive analysis of the gray level histogram of each CT scan images, this part qualitatively describe the diversity among the gray levels of the high-strength concrete specimens doped with different amount of polypropylene fiber separately at room temperature and200℃,500℃by1.5h, then analyse the reason of these diversity.(4)By extracting the the original data from different layers of a CT scan image and basised on different methods of data comparison, this part qualitatively analyse the internal composition of the high-strength concrete specimens doped with different amount of polypropylene fiber, when at room temperature and after300℃,500℃for1.5h, then analyse the formation, quantity and distribution of the inside crack with the reason for the difference.