%0 Journal Article
%A YANG Jing
%T Characteristics of Freeze-thaw Damage of Pore Structure in Concrete Material Using Nuclear Magnetic Resonance Technology
%D 2020
%R 10.11988/ckyyb.20190045
%J Journal of Yangtze River Scientific Research Institute
%P 127-131
%V 37
%N 4
%X In the purpose of obtaining variation characteristics of pore distribution for material under freeze-thaw cycles, Nuclear magnetic resonance (NMR) technique was employed in this research to scan concrete specimens undergone 0, 50, 100, and 200 times of freeze-thaw cycles. The spectrum of relaxation time <i>T<sub>2</sub></i> and NMR scanning images were acquired. The variation of <i>T<sub>2</sub></i> distribution curve reflected the evolution and expansions of pores in the specimen undergone freeze-thaw cycles. With the proceeding of cyclic freezing and thawing, the <i>T<sub>2</sub></i> spectral area which characterizes the porosity of the materials surged in the initial stage; but such increment attenuated later. The proportion of small pores reduced whereas the ratio of macropores increased. The NMR scanning images of concrete specimen with various damage degrees synchronized well with the variations of <i>T<sub>2</sub></i> distribution spectrum, which implied the accuracy of scanning results. In conclusion, the joint failure due to the combined action of osmotic force and frost heave force in freeze-thaw cycles is the fundamental cause for the formation of connecting fracture.
%U http://ckyyb.crsri.cn/EN/10.11988/ckyyb.20190045