scholarly journals Experiment on Size Effect and Fractal Characteristics of Waste Brick and Concrete Recycled Aggregate

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Hongbo Li ◽  
Hubiao Zhang ◽  
Pengfei Yan ◽  
Yufei Tong ◽  
Changyu Yan ◽  
...  
Keyword(s):  
Particle Size ◽  
Fractal Dimension ◽  
Size Effect ◽  
Single Particle ◽  
Static Load ◽  
Impact Load ◽  
Apparent Size ◽  
Recycled Aggregate ◽  
Crushing Strength ◽  
Fractal Characteristics

Herein, the size effect of single-particle crushing of recycled brick and concrete recycled macadam under static load and the fractal characteristics of aggregate under impact load are investigated. The mechanical change law of recycled macadam after compaction crushing under static load is analyzed through single-particle load crushing and impact crushing tests with different particle groups. Furthermore, the fractal dimension D is introduced to study the effects of impact energy, particle size, and different materials on the fractal characteristics of the recycled macadam. Consequently, the material, shape, and particle size of a single-particle significantly affect the crushing strength under static loading, and there is an apparent size effect on the crushing strength. Moreover, the proportion of unbroken particles in the overall mass sieve increased with decreasing particle group order under impact loading. The proportion of unbroken particles in the 4.75–9.5-mm group constituted more than 60% of the total, indicating that its anticrushing ability was significant. In addition, the model relationship between fractal dimension D, nonuniformity coefficient, and curvature coefficient is established. When 1.887 ≤ D ≤ 2.631, the gradation of recycled macadam is superior.

Particle Size Effect on Load Transfer in Single Particle Composite Samples via X-Ray Diffraction

2015 ◽  
Author(s):  
Erik Durnberg ◽  
Kevin Knipe ◽  
Gregory Freihofer ◽  
Imad Hanhan ◽  
Renfei Feng ◽  
...  
Keyword(s):  
Particle Size ◽  
Size Effect ◽  
Single Particle ◽  
Load Transfer ◽  
Particle Size Effect ◽  
X Ray Diffraction ◽  
Particle Composite ◽  
X Ray ◽  
Composite Samples

Application of Fractal Theory on the Cement Stabilized Recycled Course Aggregate Base Material

2013 ◽  
Vol 639-640 ◽  
pp. 389-393
Author(s):  
Jian Yin ◽  
Yi Chi ◽  
Wei Min Song
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Fractal Dimension ◽  
Unconfined Compressive Strength ◽  
Coarse Aggregate ◽  
Fractal Theory ◽  
Base Material ◽  
Recycled Aggregate ◽  
Material Strength ◽  
Recycled Coarse Aggregate

This paper studied different size-distribution of recycled coarse aggregates by fractal theory. Cement Stabilized Recycled Aggregate Mixture were prepared by different fractal rate aggregate gradations and the unconfined compressive strength at 7 d and 28 d of the materials were tested. The results showed that the unconfined compressive strength at 7 d and 28 d of the materials with recycled coarse aggregate were higher than the one with natural aggregate when coarse aggregate gradations were same. The higher source rock strength of recycled coarse aggregate was, the larger base material strength was. Generally, the increase of fractal dimension is conducive to the growth of strength. The base materials performances of the same fractal dimension were different when the max particle size was different. So the fractal dimension of recycled coarse aggregate must be determined by maximum particle size.

scholarly journals Numerical Simulation of Rockfill Materials Based on Fractal Theory

2021 ◽  
Vol 12 (1) ◽  
pp. 289
Author(s):  
Hongxing Han ◽  
Yun Ma ◽  
Wei He ◽  
Weifang Yang ◽  
Xudong Fu
Keyword(s):  
Particle Size ◽  
Fractal Dimension ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fine Particles ◽  
Mechanical Performance ◽  
Fractal Theory ◽  
Two Dimensions ◽  
Performance Indexes ◽  
Fractal Characteristics

With the use of the particle flow code in two dimensions, a fractal model is established with the number of particles of different particle fractions used as the statistics to study the fractal characteristics of particle size distribution. Numerically simulated specimens obtained by four scale methods are subjected to the relative density test and the biaxial compression test to explore the influences of fractal dimension D on the macroscopic and mesomechanical properties of specimens, as well as to study the relationship between fractal dimension D and different mechanical performance indexes. Results show that the particle size distribution of each of the four groups after scale exhibits fractal characteristics, with the fractal dimension D ranging from 1.27 to 2.03. The number of fine particles in the specimen increases with the fractal dimension D, the particle aggregates become more compact, the macroscopic mechanical properties of the specimens are improved, and a linear relationship exists between the fractal dimension D and different mechanical performance indexes. A large fractal dimension D corresponds to a great mesoparticle coordination number.

scholarly journals Investigation on Coal Fragmentation by High-Velocity Water Jet in Drilling: Size Distributions and Fractal Characteristics

2018 ◽  
Vol 8 (10) ◽  
pp. 1988 ◽  
Author(s):  
Songqiang Xiao ◽  
Zhaolong Ge ◽  
Yiyu Lu ◽  
Zhe Zhou ◽  
Qian Li ◽  
...  
Keyword(s):  
Particle Size ◽  
Fractal Dimension ◽  
Impact Velocity ◽  
Fragment Size ◽  
Water Jet ◽  
Particle Sizes ◽  
Size Distributions ◽  
Jet Impact ◽  
Fractal Characteristics ◽  
Coal Strength

Water jet drilling (WJD) technology is a highly efficient method to extract coalbed methane from reservoirs with low permeability. It is crucial to efficiently remove the coal fragments while drilling. In this study, to disclose coal fragmentation features and size distributions under water jet impact in drilling, the image processing method was utilized to obtain the geometric dimensions of coal fragments. The size distributions, morphologies and fractal characteristics of coal fragmentation were studied based on generalized extreme value distribution and fractal theory. The effects of the jet impact velocity and coal strength on the fragmentation features were analyzed. The results show that fine particles dominate the coal fragments in WJD for coal seams with various strengths. In experiments conducted at the Fengchun coal mine, owing to the higher coal strength of the M7 coal seam, the fragmentation degree of coal subjected to water jets during WJD is lower in the M7 coal steam than in the M8 coal seam, which results in a large dominant fragment size and small fractal dimension under the same impact energy. It was found that the higher the jet impact velocity is, the higher the quantity of fragments generated from WJD and the smaller the particle size. The NUM-based cumulative probability distribution curves of coal fragments are more intensive in the range of relatively small particle sizes and then become sparser with the increase in particle size. When the impact velocity increases, (i) the size distribution curves move toward smaller particle sizes, and the dominant fragment size decreases; (ii) the shape (major axis/minor axis) of coal fragments move toward the upper left, and the curve shape for a high impact velocity attains unity more quickly; and (iii) the fractal dimension value increases linearly. In addition, the fractal dimensions are obviously affected by the dominant fragment size; they increase with the decrease in the dominant fragment size. This study can provide a basis for further research on coal fragment transportation in WJD and parameter selection for discharging coal fragments during drilling for CBM development.

Multi-fractal characteristics of particle size distribution of granular backfilling materials under different loads

2018 ◽  
Vol 60 (2) ◽  
pp. 202-208 ◽  
Author(s):  
Hao Yan ◽  
Jixiong Zhang ◽  
Jiaqi Wang ◽  
Nan Zhou ◽  
Sheng Zhang
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fractal Characteristics

scholarly journals Experimental Study on the Mechanical Properties and Compression Size Effect of Recycled Aggregate Concrete

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2323
Author(s):  
Yubing Du ◽  
Zhiqing Zhao ◽  
Qiang Xiao ◽  
Feiting Shi ◽  
Jianming Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Size Effect ◽  
Compressive Stress ◽  
Failure Modes ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Substitution Ratio ◽  
The Impact

To explore the basic mechanical properties and size effects of recycled aggregate concrete (RAC) with different substitution ratios of coarse recycled concrete aggregates (CRCAs) to replace natural coarse aggregates (NCA), the failure modes and mechanical parameters of RAC under different loading conditions including compression, splitting tensile resistance and direct shear were compared and analyzed. The conclusions drawn are as follows: the failure mechanisms of concrete with different substitution ratios of CRCAs are similar; with the increase in substitution ratio, the peak compressive stress and peak tensile stress of RAC decrease gradually, the splitting limit displacement decreases, and the splitting tensile modulus slightly increases; with the increase in the concrete cube’s side length, the peak compressive stress of RAC declines gradually, but the integrity after compression is gradually improved; and the increase in the substitution ratio of the recycled aggregate reduces the impact of the size effect on the peak compressive stress of RAC. Furthermore, an influence equation of the coupling effect of the substitution ratio and size effect on the peak compressive stress of RAC was quantitatively established. The research results are of great significance for the engineering application of RAC and the strength selection of RAC structure design.

Effects of maximum particle size of coarse aggregates and steel fiber contents on the mechanical properties and impact resistance of recycled aggregate concrete

2021 ◽  
pp. 136943322110179
Author(s):  
DongTao Xia ◽  
ShaoJun Xie ◽  
Min Fu ◽  
Feng Zhu
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Steel Fiber ◽  
Impact Resistance ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Coarse Aggregates ◽  
Maximum Particle Size ◽  
Maximum Particle

Fiber reinforced recycled aggregate concrete has become a new type of green concrete material. The maximum particle size of coarse aggregates and steel fiber contents affect the mechanical properties and impact resistance of recycled aggregate concrete. However, such studies are rare in literature. The present paper shortens the gap through experimental study. A total of 144 specimens of 12 kinds of concrete mixtures were tested, which adopted different steel fiber volume admixtures (0%, 0.8%, 1.0%, 1.2%) and recycled coarse aggregates in different maximum particle sizes (9.5, 19, 31.5 mm) replacing 30% natural coarse aggregate. The compressive strength, splitting tensile strength, and impact resistance of the 12 concrete mixtures were tested. The results showed that the compressive strength, splitting tensile strength, and impact resistance of recycled aggregate concrete increased first and then decreased with the increase of the maximum particle size. The recycled aggregate concrete with the maximum particle size of 19 mm had the highest mechanical properties and impact resistance. Besides, with the increase of steel fiber content, the compressive strength, splitting tensile strength, and impact resistance of recycled aggregate concrete showed an increasing trend. Considering a large amount of experimental data and the coupling effect of steel fiber contents and the maximum particle size of coarse aggregates, the Weibull distribution function was introduced to analyze the impact test results and predict the number of resistance to impact under different failure probabilities. The results showed that the number of blows of the recycled aggregate concrete followed a two-parameter Weibull distribution, and the estimated value of the number of resistance to impact for failure increased with the increase of the failure probability.

Sign in / Sign up

Export Citation Format

Share Document