Laboratory Investigation of the Effect of Particle Shape Characteristics and Gradation of Aggregates on the Skid Resistance of Asphalt Surface Mixtures

2009 ◽  
pp. 117-117-21 ◽  
Author(s):  
EY Huang ◽  
T Ebrahimzadeh
Keyword(s):  
Laboratory Investigation ◽  
Particle Shape ◽  
Skid Resistance ◽  
Shape Characteristics

scholarly journals Prediction Model of Minimum Void Ratio for Various Sizes/Shapes of Sandy Binary Mixture

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Chaojie Shen ◽  
Zhaoyang Xu ◽  
Jie Yin ◽  
Jinfeng Wu
Keyword(s):  
Particle Size ◽  
Binary Mixture ◽  
Particle Shape ◽  
Void Ratio ◽  
Soil Mechanics ◽  
Influence Factors ◽  
Natural Sand ◽  
Undetermined Coefficient ◽  
Shape Characteristics ◽  
Different Origins

The minimum void ratio is a fundamental physical index for evaluating particle properties in soil mechanics, ceramic processing, and concrete mixes. Previous research found that both particle size distribution and particle shape characteristics would affect minimum void ratio, while the current research generally uses a linear model to estimate the minimum void ratio of a binary mixture, ignoring quantitative effect of particle shape on the minimum void ratio. Based on a study of binary mixtures of natural sand from three different origins and iron particles of two different shapes, this paper analyzes the influence factors of the minimum void ratio, and a quadratic nonlinear model is proposed for estimating the minimum void ratio of binary mixture. The model contains only one undetermined coefficient, a, the value of which is correlated to the particle sphericity, particle size, and particle size ratio. A theoretical calculation formula for the coefficient a is proposed to quantitatively analyze the effects of these three factors on the size of the parameters. In the end, the model is used to estimate the minimum void ratios of sand and substitute particles from different producing areas; the average difference between the estimated values and the fitted values is about 2.03%, suggesting that the estimated values of the model fit well with the measured data.

scholarly journals Influence of soil particle shape on saturated hydraulic conductivity

2017 ◽  
Vol 65 (1) ◽  
pp. 80-87 ◽  
Author(s):  
Zofia Zięba
Keyword(s):  
Hydraulic Conductivity ◽  
Particle Shape ◽  
Pore Diameter ◽  
Grain Shape ◽  
Saturated Hydraulic Conductivity ◽  
Analytical Models ◽  
Particle Structure ◽  
Constant Head ◽  
Shape Characteristics ◽  
The Relationship

AbstractThe aim of this paper is to define the correlation between the geometry of grains and saturated hydraulic conductivity of soils. The particle shape characteristics were described by the ζ0Cindex (Parylak, 2000), which expresses the variability of several shape properties, such as sphericity, angularity and roughness.The analysis was performed on samples of four soils, which were characterised by the same grain size distribution and extremely different particle structure. The shape characteristics varied from ideally spherical, smooth grains (glass microbeads GM) to highly irregular and rough particles (fly ash FA).For each soil, laboratory tests of saturated hydraulic conductivity (constant head test CHT and falling head test FHT) were performed. Additionally, an empirical analysis of effective pore diameter was conducted with use of the analytical models developed by Pavchich (Wolski, 1987) and Indraratna and Vafai (1997). The models were modified by introducing the ζ0Cindex.Experiments have shown that saturated hydraulic conductivity depends on grains shape and surface roughness. This parameter decreases with the increase in the irregularity of soil particles. Moreover, it was proven that the ζ0Creflects the relationship between effective pore diameter and grain shape characteristics.

scholarly journals Effect of aggregate particle shape and granulometry on the workability and mechanical properties of glass reinforced concrete

2019 ◽  
Author(s):  
Rimvydas Moceiki ◽  
Asta Kičaitė ◽  
Gintautas Skripkiūnas
Keyword(s):  
Reinforced Concrete ◽  
Particle Shape ◽  
Glass Fibers ◽  
Round Shape ◽  
Crushed Granite ◽  
Glass Fibre Reinforced ◽  
Numeric Representation ◽  
Shape Characteristics ◽  
Good Workability ◽  
Fibre Matrix

Modern alkali resistant glass fibers (ARG) modified with 17% ZrO2 are getting more popular as reinforcement of cementitious matrixes. Typical matrix compositions with quartz, Portland cement, 13 mm length ARG glass fibres and PCE superplasticizer can offer good workability, product quality and highly increased mechanical characteristics. In production of self compacting fibre reinforced premix highly siliceous fine sands with nearly round shape particles are usually preferred. This article investigates influence of particle shape for workability of glass fibre reinforced concrete when alternative fillers- crushed granite and regular sand are used. 12 compositions were made whith different quantities of fillers, changing quartz from 0% to 50% with alternative aggregates. Slump tests according to EN 1170-1 were made and showed major impact of particle shape characteristics on mix workability. When quantity of altrernative aggrates was increased, slump of fresh mix decreased and fibre- matrix segregation occurred. New workability factor W is offered and values calculated, to have numeric representation of workability. Alternative aggregates had no clear influence for flexural strenght, when beams 40×40×160 were tested. Compressive strength dropped by 25% when regular sand was used. Typical quartz matrix resulted in lower water absorbtion.

Submerged Arc Spray Synthesis of TiO2 Nanoparticles with Desired Form Sphericity Using Process Characterization and Optimization

2008 ◽  
Vol 8 (2) ◽  
pp. 518-526 ◽  
Author(s):  
Liang-Chia Chen ◽  
Chie-Chan Ho
Keyword(s):  
Process Parameters ◽  
Particle Shape ◽  
Nanoparticle Synthesis ◽  
Metal Nanoparticle ◽  
Synthesis Process ◽  
Arc Spray ◽  
Process Characterization ◽  
Product And Process ◽  
Shape Characteristics ◽  
Submerged Arc

This article presents a study on process characterization and optimization of the metal nanoparticle fabrication process known as the submerged arc spray nanoparticle synthesis system (SANSS) for obtaining desired geometric sphericity of nanoparticles. The geometric shape characteristics of nanoparticles pose significant impact on innovative product and process design. The sphericity and surface roughness of prepared TiO2 nanoparticles can vary widely and are influenced by the process parameters being employed in the SANSS. To improve this, an in-situ nanofluid sampling and measurement approach was developed to analyze the particle shape characteristics and characterize the nanoparticle synthesis process. The particle shape contours obtained from FE-SEM and TEM were employed to quantify the TiO2 nanoparticle sphericity and analyze the effect of process parameters on particle roundness. The optimized process parameters were identified using the Taguchi method. Our results proved that the average sphericity of TiO2 particles prepared using the optimized process parameters was effectively improved up to three folds.

scholarly journals Shape Characteristics of Coral Sand from the South China Sea

2020 ◽  
Vol 8 (10) ◽  
pp. 803 ◽  
Author(s):  
Xing Wang ◽  
Yang Wu ◽  
Jie Cui ◽  
Chang-Qi Zhu ◽  
Xin-Zhi Wang
Keyword(s):  
Particle Size ◽  
Bulk Density ◽  
Quartz Sand ◽  
Particle Shape ◽  
Fractal Theory ◽  
Skewed Distribution ◽  
Shape Parameters ◽  
Coral Sand ◽  
Particle Images ◽  
Shape Characteristics

The particle shape of coral sand is a crucial factor that affects its accumulation characteristics. Two-dimensional particle images of coral sand with different particle sizes were obtained through optical imaging, and the basic size parameters of particles were measured by digital image processing. The particle shape parameters were created, and on this basis, the variation of shape parameters with size, the distribution characteristics, and the sensitivity of shape parameters were analyzed by mathematical statistics and the fractal theory. In addition, a comparative analysis was conducted for the particle shape and bulk density of coral sand and quartz sand with the same particle size. The results show that (1) for coral sand with particle size ranging from 0.5 to 5.0 mm, as the particle size augments, its overall profile coefficient grows, while the flatness, angularity, and roughness diminish and the particle shape deviates more from the regular circle. (2) The shape of coral sand particles exhibits good fractal characteristics, and the particle shape gets more complex as the particle size grows as evidenced by the fact that the fractal dimension enlarges. (3) All the shape parameters obey a skewed distribution. Concerning the sensitivity to the change in particle shape, the flatness occupies the first place, the overall profile coefficient and angularity come second, and the roughness ranks third, accordingly. It is suggested that flatness should be preferred as the evaluation parameter of the particle shape. (4) Compared with that of quartz sand, the particle shape of coral sand is more irregular, and the intergranular pores are larger under the same accumulation conditions, which is the primary reason why the specific gravity of coral sand is greater than that of quartz sand while the bulk density is smaller than that of quartz sand.

Anisotropic Resilient Modulus Model of Granular Materials Based on Particle Characteristics

2021 ◽  
pp. 036119812110237
Author(s):  
Zefeng Tao ◽  
Zengyi Wang ◽  
Jianming Ling ◽  
Yu Tian ◽  
Juewei Cai ◽  
...  
Keyword(s):  
Particle Size ◽  
Granular Materials ◽  
Particle Shape ◽  
Resilient Modulus ◽  
Design Procedure ◽  
Triaxial Tests ◽  
Model Parameters ◽  
Anisotropic Particles ◽  
Particle Characteristics ◽  
Shape Characteristics

Granular materials are widely used for bases or subbases in pavement structures. They typically exhibit strong anisotropic properties which relate to stress states and particle characteristics. The conventional design procedure for flexible pavements underestimates the anisotropy of resilient moduli. This study established an anisotropic resilient modulus model for granular materials that considered gradation and particle shape characteristics. Vertical and horizontal resilient moduli of certain granular materials were measured in self-developed triaxial tests to obtain corresponding model parameters and anisotropic coefficients. Gradation and particle shape models were established to quantify the granular material characteristics, and the parameters were regressed. Particle shapes were obtained via image processing, and the ratio ( η) of particle sphericity to roundness was chosen as a shape parameter. Results show that η increases with the decrease in particle size, and the average values of η for graded gravel and natural laterite are 0.54 and 0.63, respectively. The η distribution curves indicate that the proportion of relatively anisotropic particles, rather than extremely anisotropic particles, results in the differences in particle shape characteristics. The regression relationship between the anisotropic calculation parameters and the model parameters of vertical resilient modulus, gradation, and particle shape was established. Thus, the horizontal resilient modulus and the anisotropic coefficient can be predicted via conventional resilient modulus tests and gradation, and particle shape analysis. This study shows that the anisotropy of granular materials decreases with the increase in coarse particles and the uniformization of the particle size distribution, and it increases with the increase in anisotropic particles and the polarization of the η distribution.

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