Abstract
In order to study the fractal characteristics and energy dissipation of concrete suffered freeze-thaw cycle actions and impact loading, C35 concrete was taken as the research object in this paper, and freeze-thaw cycle tests were carried out with a freeze-thaw range of −20 °C~20 °C and a freeze-thaw frequency of 0~50 times. The degradation characteristics of concrete material and the variation rules of basic physical parameters under various freeze-thaw cycle conditions were obtained consequently. By using the SHPB (separated Hopkinson pressure bar) test device, impact compression tests of concrete specimens under different freeze-thaw cycle actions were developed, then the process of impact crushing and the mechanism of damage evolution were analyzed. Based on the screening statistical method and the fractal theory, the scale-mass distribution rules and fractal dimension characteristics of crushing blocks are investigated. Furthermore, the absorption energy, fracture energy and block kinetic energy of concrete under different conditions were calculated according to the energy dissipation principle of SHPB test. The relationship between the energy consumption density and the fractal dimension of fragments was established, and the coupling effect mechanism of freeze-thaw cycle action and strain rate effect on the fractal characteristics and energy consumption was revealed additionally. The research results show that the concrete under different freeze-thaw cycle conditions and impact loading speeds has fractal properties from the microscopic damage to the macroscopic fracture. The energy dissipation is intrinsically related to the fractal characteristics, and the energy consumption density increases with the increase of the fractal dimension under a certain freeze-thaw cycle condition. When at a certain loading speed, with the growth of freeze-thaw cycles, the energy consumption density reduces under the same fractal dimension, while the fractal dimension improves under the same energy consumption density.
Highlights
Concrete is the most widely used building material in the fields of national defense, civil defense and civil construction engineering [1]
Studying the broken characteristics and energy dissipation of concrete under freeze-thaw cycle actions and impact loadings is of great theoretical value and practical significance to reasonably design the anti-impact of concrete protection projects in cold regions, and evaluate and reinforce the safety of post-disaster concrete structures
In this paper, directed to the concrete specimens suffered from different freeze-thaw cycles (0, 10, separated Hopkinson pressure bar (SHPB) device (LiWei Technology Co., Ltd, Luoyang, China, 20, 30, 40 and 50), the dynamic uniaxial compression tests were carried out on the Φ 50 mm separated shown in Figure 3) with three loading speeds (5.4 m/s, 8.8 m/s, and 11.3 m/s)
Summary
Concrete is the most widely used building material in the fields of national defense, civil defense and civil construction engineering [1]. Studies have shown that [6,7,8,9,10], there are distributed at random a large number of mesoscopic damage structures inside the concrete, including pore spaces, microcracks, weak impurities and so on, whose distribution rules and geometrical shapes have significant statistical self-similarity within a certain range. These mesoscopic damage structures gestate, develop and converge continuously under the outer loads, the broken blocks of concrete have a certain fractal characteristics. On the basis of the fractal theory and the energy dissipation principle of SHPB test, the fractal dimension and energy consumption characteristics of concrete fragments were analyzed, the relationship of energy consumption density and fractal dimension was established, and the influence mechanism of freeze-thaw cycle action and load speed was revealed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
