Research on Fractal Characteristics and Energy Dissipation of Concrete Suffered Freeze-Thaw Cycle Action and Impact Loading

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.

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Research on the Fractal Characteristics and Energy Dissipation of Basalt Fiber Reinforced Concrete after Exposure to Elevated Temperatures under Impact Loading

Materials ◽

10.3390/ma13081902 ◽

2020 ◽

Vol 13 (8) ◽

pp. 1902

Author(s):

Wenbiao Liang ◽

Junhai Zhao ◽

Yan Li ◽

Yue Zhai

Keyword(s):

Fractal Dimension ◽

Energy Consumption ◽

Reinforced Concrete ◽

Energy Dissipation ◽

Impact Velocity ◽

Impact Loading ◽

Basalt Fiber ◽

Fiber Content ◽

Fiber Reinforced Concrete ◽

Fractal Characteristics

The fractal characteristics and energy dissipation of basalt fiber reinforced concrete (BFRC) with five kinds of fiber volume contents (0.0%, 0.1%, 0.2%, 0.3%, 0.4%) after exposure to different temperatures (20 °C, 200 °C, 400 °C, 600 °C, 800 °C) under impact loading were investigated by using a 50 mm diameter split Hopkinson pressure bar (SHPB) apparatus. Scale-mass distribution rules and fractal dimension characteristics of fragments were studied based on the screening statistical method and the fractal theory. Furthermore, the relationship between the energy consumption density and the fractal dimension of fragments was established, and the effects of fiber content, temperature and impact velocity on fractal dimension and absorption energy were analyzed. The results show that the crushing severity of fragments and fractal dimension increase with the impact velocity under the same fiber content. The energy consumption density increases first and then decreases with increasing fiber content, and also decreases with increasing temperature. When the temperature and fiber content remain unchanged, the energy consumption density increases linearly with the increasing fractal dimension, and under the same impact velocity and temperature, there is no obvious linear relationship between energy consumption density and fractal dimension.

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Study on the Fractal Characteristics of the Pomegranate Biotite Schist under Impact Loading

Geofluids ◽

10.1155/2021/1570160 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Jianguo Wang ◽

Ting Zuo ◽

Xianglong Li ◽

Zihao Tao ◽

Jun Ma

Keyword(s):

Compressive Strength ◽

Fractal Dimension ◽

Energy Consumption ◽

Energy Dissipation ◽

Strain Rate ◽

Power Relationship ◽

Strain Rates ◽

Biotite Schist ◽

Fractal Characteristics ◽

Dynamic Compressive Strength

In order to study the fractal characteristics of the pomegranate biotite schist under the effect of blasting loads, a one-dimensional SHPB impact test was carried out to test the dynamic compressive strength, damage morphology, fracture energy dissipation density, and other parameters of the rocks under different strain rates; besides, sieve tests were conducted to count the mass fractal characteristics of the crushed masses under different strain rates to calculate the fractal dimension of the crushed rock D . Finally, the relationships between fractal dimension and dynamic compressive strength, crushing characteristics, and energy dissipation characteristics were analysed. The results show that under different impact loads, the strain rate effect of the rock is significant and the dynamic compressive strength increases with the increasing strain rate, and they show a multiplicative power relationship. The higher the strain rate of the rock, the deeper the fragmentation and the higher the fractal dimension, and the fractal dimension and rock crushing energy density are multiplied by a power relationship. By performing the comparative analysis of the pomegranate biotite schist, a reasonable strain rate range of 78.75 s-1~82.51 s-1 and a reasonable crushing energy consumption density range of 0.78 J·cm-3~0.92 J·cm-3 were determined. This research provides a great reference for the analysis of dynamic crushing mechanism, crushing block size distribution, and crushing energy consumption of the roadway surrounding rock.

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Experimental investigation on combined modification for micro physicochemical characteristics of coal by compound reagents and liquid nitrogen freeze-thaw cycle

Fuel ◽

10.1016/j.fuel.2021.120287 ◽

2021 ◽

Vol 292 ◽

pp. 120287

Author(s):

Weibo Han ◽

Gang Zhou ◽

Junpeng Wang ◽

Wenjing Jiang ◽

Qian Zhang ◽

...

Keyword(s):

Experimental Investigation ◽

Liquid Nitrogen ◽

Physicochemical Characteristics ◽

Freeze Thaw ◽

Thaw Cycle ◽

Freeze Thaw Cycle

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The effect of freeze–thaw cycle on the low-temperature properties of asphalt fine aggregate matrix utilizing bending beam rheometer

Cold Regions Science and Technology ◽

10.1016/j.coldregions.2016.02.008 ◽

2016 ◽

Vol 125 ◽

pp. 101-107 ◽

Cited By ~ 20

Author(s):

Xiangbing Gong ◽

Pedro Romero ◽

Zejiao Dong ◽

Daniel Scott Sudbury

Keyword(s):

Low Temperature ◽

Fine Aggregate ◽

Bending Beam Rheometer ◽

Freeze Thaw ◽

Thaw Cycle ◽

Freeze Thaw Cycle ◽

Fine Aggregate Matrix

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Effect of freeze–thaw cycle on physical and mechanical properties and damage characteristics of sandstone

Scientific Reports ◽

10.1038/s41598-021-91842-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Longxiao Chen ◽

Kesheng Li ◽

Guilei Song ◽

Deng Zhang ◽

Chuanxiao Liu

Keyword(s):

Mechanical Properties ◽

Shear Failure ◽

Triaxial Compression ◽

Physical And Mechanical Properties ◽

Freeze Thaw ◽

Damage Characteristics ◽

Large Pore ◽

Natural Rock ◽

Thaw Cycle ◽

Freeze Thaw Cycle

AbstractRock deterioration under freeze–thaw cycles is a concern for in-service tunnel in cold regions. Previous studies focused on the change of rock mechanical properties under unidirectional stress, but the natural rock mass is under three dimensional stresses. This paper investigates influences of the number of freeze–thaw cycle on sandstone under low confining pressure. Twelve sandstone samples were tested subjected to triaxial compression. Additionally, the damage characteristics of sandstone internal microstructure were obtained by using acoustic emission (AE) and mercury intrusion porosimetry. Results indicated that the mechanical properties of sandstone were significantly reduced by freeze–thaw effect. Sandstone’ peak strength and elastic modulus were 7.28–37.96% and 6.38–40.87% less than for the control, respectively. The proportion of super-large pore and large pore in sandstone increased by 19.53–81.19%. We attributed the reduced sandstone’ mechanical properties to the degenerated sandstone microstructure, which, in turn, was associated with increased sandstone macropores. The macroscopic failure pattern of sandstone changed from splitting failure to shear failure with an increasing of freeze–thaw cycles. Moreover, the activity of AE signal increased at each stage, and the cumulative ringing count also showed upward trend with the increase of freeze–thaw number.

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Non-linear creep damage model of sandstone under freeze-thaw cycle

Journal of Central South University ◽

10.1007/s11771-021-4656-3 ◽

2021 ◽

Vol 28 (3) ◽

pp. 954-967

Author(s):

Jie-lin Li ◽

Long-yin Zhu ◽

Ke-ping Zhou ◽

Hui Chen ◽

Le Gao ◽

...

Keyword(s):

Damage Model ◽

Creep Damage ◽

Freeze Thaw ◽

Thaw Cycle ◽

Linear Creep ◽

Non Linear ◽

Freeze Thaw Cycle ◽

Creep Damage Model

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Strength and Microscopic Damage Mechanism of Yellow Sandstone with Holes under Freezing and Thawing

Advances in Civil Engineering ◽

10.1155/2020/5921901 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13 ◽

Cited By ~ 1

Author(s):

Huren Rong ◽

Jingyu Gu ◽

Miren Rong ◽

Hong Liu ◽

Jiayao Zhang ◽

...

Keyword(s):

Mechanical Properties ◽

Pore Size ◽

Power Function ◽

Damage Mechanism ◽

Uniaxial Compression Test ◽

Freezing And Thawing ◽

Freeze Thaw ◽

Thaw Cycle ◽

Freeze Thaw Cycle ◽

Microscopic Damage

In order to study the damage characteristics of the yellow sandstone containing pores under the freeze-thaw cycle, the uniaxial compression test of saturated water-stained yellow sandstones with different freeze-thaw cycles was carried out by rock servo press, the microstructure was qualitatively analyzed by Zeiss 508 stereo microscope, and the microdamage mechanism was quantitatively studied by using specific surface area and pore size analyzer. The mechanism of weakening mechanical properties of single-hole yellow sandstone was expounded from the perspective of microstructure. The results show the following. (1) The number of freeze-thaw cycles and single-pore diameter have significant effects on the strength and elastic modulus of the yellow sandstone; the more the freeze-thaw cycles and the larger the pore size, the lower the strength of the yellow sandstone. (2) The damage modes of the yellow sandstone containing pores under the freeze-thaw cycle are divided into five types, and the yellow sandstone with pores is divided into two areas: the periphery of the hole and the distance from the hole; as the number of freeze-thaw cycles increases, different regions show different microscopic damage patterns. (3) The damage degree of yellow sandstone is different with freeze-thaw cycle and pore size. Freeze-thaw not only affects the mechanical properties of yellow sandstone but also accelerates the damage process of pores. (4) The damage of the yellow sandstone by freeze-thaw is logarithmic function, and the damage of the yellow sandstone is a power function. The damage equation of the yellow sandstone with pores under the freezing and thawing is a log-power function nonlinear change law and presents a good correlation.

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Studies the Properties of Polyaspartic Polyurea Coated Concrete under Coaction of Salt Fog and Freeze-Thaw

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.455-456.781 ◽

2012 ◽

Vol 455-456 ◽

pp. 781-785

Author(s):

Ping Lu ◽

Xin Mao Li ◽

Xue Qiang Ma ◽

Wei Bo Huang

Keyword(s):

Elastic Modulus ◽

Frost Resistance ◽

Dynamic Elastic Modulus ◽

Freeze Thaw ◽

Decrease Rate ◽

Thaw Cycle ◽

Freeze Thaw Cycle ◽

Salt Fog

. This paper mainly studied the properties of PAE polyurea coated concrete under coactions of salt fog and freeze-thaw. After exposed salt fog conditions for 200d, T3, B2, F2 and TM four coated concrete relative dynamic elastic modulus have small changes, but different coated concrete variation amplitude is different. T3 coated concrete after 100 times of freeze-thaw cycle the relative dynamic elastic modulus began to drop, 200 times freeze-thaw cycle ends, relative dynamic elastic modulus variation is the largest, decrease rate is 95%, TM concrete during 200 times freeze-thaw cycle, relative dynamic elastic modulus almost no change, B2 concrete and F2 concrete the extent of change between coating T3 and TM. After 300 times the freeze-thaw cycle coated concrete didn't appear freeze-thaw damage phenomenon. Four kinds of coating concrete relative dynamic elastic modulus variation by large to small order: T3 coated concrete > B2 coated concrete >F2 coated concrete > TM coated concrete, concrete with the same 200d rule. Frost resistance order, by contrast, TM coated concrete > B2 coated concrete > F2 coated concrete > T3 coated concrete.

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