scholarly journals Kiessande für sekundäre Strassen | Aggregates for Low Volume Roads

2000 ◽  
Vol 151 (10) ◽  
pp. 398-402
Author(s):  
Richard Hirt
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fine Particles ◽  
Road Construction ◽  
Point Of View ◽  
Crushed Rock ◽  
Rural Roads ◽  
Low Volume Roads ◽  
Low Volume

Gravel is the most important material for road construction. In most countries the quality of gravel for sub-base and base is standardised. The Association of Swiss Road and Traffic Engineers recently revised the Swiss SN standard 670 120d for subbase gravel. Quality requirements concerning the admissible content of fine particles and the limits of particle size distribution were intensified, for no obvious reason. Former studies and experiences proved that these stricter specifications are neither necessary, from a soil-mechanical point of view, nor economical. For low volume roads, such as forest and rural roads, it is therefore suggested to use the limits of particle size distribution for gravel II (except for crushed rock aggregates),but a clearly higher amount of fine particles can be accepted.

The Role of Particle Size Distribution in the Performance and Modelling of Filtration

1993 ◽  
Vol 27 (10) ◽  
pp. 19-34 ◽  
Author(s):  
R. I. Mackie ◽  
R. Bai
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fine Particles ◽  
Coarse Particles ◽  
Large Particles

The paper examines the importance of size distribution of the influent suspension on the performance of deep bed filters and its significance with regard to modelling. Experiments were carried out under a variety of conditions using suspensions which were identical in every respect apart from their size distribution. The results indicate that the presence of coarse particles does increase the removal of fine particles. Deposition of fine particles leads to a greater headloss than deposition of large particles. Changes in size distribution with time and depth play an important role in determining the behaviour of a filter, and models of both removal and headloss development must take account of this.

Performance Characteristics of Centrifugal Slurry Pumps

2001 ◽  
Vol 123 (2) ◽  
pp. 271-280 ◽  
Author(s):  
B. K. Gandhi ◽  
S. N. Singh ◽  
V. Seshadri
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fine Particles ◽  
Performance Characteristics ◽  
Solid Concentration ◽  
Solid Materials ◽  
Power Characteristics ◽  
Additional Losses

The performance of two centrifugal slurry pumps has been reported for three solid materials having different particle size distribution (PSD) in terms of head, capacity, and power characteristics. The results have shown that the values of head and efficiency ratios are not only dependent on solid concentration but are also affected by PSD of the solids and properties of the slurry. The addition of fine particles in the slurry of coarser material leads to reduction in the additional losses that occur in the pumps due to the presence of solids. It is also observed that with the increase in the pump size, the additional losses due to presence of solids reduce.

Particle Size Distribution Measurement of Free-Falling Fine Particles in a Dusty Plasma Experiment

2001 ◽  
Vol 40 (Part 1, No. 5A) ◽  
pp. 3433-3434
Author(s):  
Nobuki Kawashima ◽  
Kazuya Takeda ◽  
Takeharu Etoh ◽  
Kousei Takehara ◽  
Haruya Kubo ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Dusty Plasma ◽  
Fine Particles ◽  
Distribution Measurement ◽  
Plasma Experiment ◽  
Particle Size Distribution Measurement ◽  
Free Falling

MPT Influence on the Rheological Behaviour of Self-Flow Refractory Castables

2008 ◽  
Vol 587-588 ◽  
pp. 133-137 ◽  
Author(s):  
Abílio P. Silva ◽  
Ana M. Segadães ◽  
Tessaleno C. Devezas
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Mechanical Strength ◽  
Size Distribution ◽  
Fine Particles ◽  
Rheological Behaviour ◽  
Response Surfaces ◽  
Coarse Particles ◽  
Aggregate Particle ◽  
Refractory Castables

The success of a refractory castable is largely due to the quality of its properties and ease of application. Self-flow refractory castables (SFRC), with high flowability index (>130%), can be easily accommodated in a mould without the application of external energy, being ideal for the manufacture of monolithic linings. SFRC castables without cement require a matrix of very fine particles, which guarantees improved rheological behaviour and performs the role of the binder in the absence of the refractory cement. The presence of the aggregate (coarse particles) hinders the flowability index, but improves the castable mechanical strength and reduces firing shrinkage, and also contributes to the reduction of the castable costs. The control of the maximum paste thickness (MPT) allows the reduction of the coarse particles interference, minimizing the number of contact points among the grains and avoiding the formation of an aggregate skeleton that impairs the flowability of the mixture. In the present work, 100% alumina SFRCs without cement were produced with a fixed matrix of fine particles, whose particle size distribution was optimized using statistical techniques (mixtures design and triangular response surfaces). Different aggregate particle size distributions were used, with several MPT values, with the objective of evaluating which was the mean distance that maximized the flowability index, simultaneously ensuring good mechanical strength for the refractory castable. Ensuring a minimum surface area of 2.22m2/g, the mixtures reach the self-flow turning point with a minimum water content and the maximum flowability is obtained for an aggregate particle size distribution modulus of q=0.22, and consequently an optimized MPT value. SFRC with high mechanical strength (>60MPa) were obtained.

scholarly journals Size Characteristics of Sediments Eroded under Different Masson Pine Litter Covers in South China

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2190
Author(s):  
Fangfang Zhu ◽  
Yuchen Li ◽  
Jinhua Cheng
Keyword(s):  
Particle Size ◽  
Soil Erosion ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fine Particles ◽  
Enrichment Ratio ◽  
Coarse Particles ◽  
Characteristic Parameters ◽  
Sediment Distribution ◽  
The Relationship

The particle size distribution characteristics of runoff sediments are vital for understanding the effect of the mechanism of soil erosion on slopes. The objective of this study was to investigate the particle-size distribution of sediments eroded from slopes covered by different litter coverage masses under artificial rainfall simulation. Litter was spread on the surface of a soil tank according to different biomasses (0 g·m−2, 100 g·m−2, 200 g·m−2 and 400 g·m−2). The mean weight diameter (MWD), fractal dimension (D) and enrichment ratio (ER) are characteristic parameters of sediment particle size. The MWD and D were more sensitive to soil erosion and had a significant negative correlation with the slope angle and rainfall intensity. The performance of the MWD on the slope (5°) was less than the MWD on the slope (10°). The relationship between eroded sediment distribution characteristic parameters and the litter coverage mass had a significant influence on the content of coarse particles. The content of fine particles accelerated, decreased and then stabilized, whereas coarse particles increased first and then stabilized. The litter diameter and surface area were the main parameters that affected the MWD and D. Under different rain intensities and slopes, the ER varied inconsistently with litter coverage mass. Coarse particles were eroded easily and selectively, and soil erosion had no sorting effect on fine particles. These findings support the quantitative study of the relationship between the amount of litter coverage mass and the particle size of soil sediments.

Influence of particle-size distribution homogeneity on shearing of soils subjected to internal erosion

2020 ◽  
Vol 57 (11) ◽  
pp. 1684-1694
Author(s):  
Shijin Li ◽  
Adrian R. Russell ◽  
David Muir Wood
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Soil Sample ◽  
Size Distribution ◽  
Fine Particles ◽  
Internal Erosion ◽  
Triaxial Tests ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Homogeneous Particle

Internal erosion (suffusion) is caused by water seeping through the matrix of coarse soil and progressively transporting out fine particles. The mechanical strength and stress–strain behavior of soils within water-retaining structures may be affected by internal erosion. Some researchers have set out to conduct triaxial erosion tests to study the mechanical consequences of erosion. Prior to conducting a triaxial test they subject a soil sample, which has an initially homogeneous particle-size distribution and density throughout, to erosion by causing water to enter one end of a sample and wash fine particles out the other. The erosion and movement of particles causes heterogeneous particle-size distributions to develop along the sample length. In this paper, a new soil sample formation procedure is presented that results in homogeneous particle-size distributions along the length of an eroded sample. Triaxial tests are conducted on homogeneous samples formed using the new procedure as well as heterogeneous samples created by the more commonly used approach. Results show that samples with homogeneous post-erosion particle-size distributions exhibit slightly higher peak deviator stresses than those that were heterogeneous. The results highlight the importance of ensuring homogeneity of post-erosion particle-size distributions when assessing the mechanical consequences of erosion. Forming samples using the new procedure enables the sample’s response to triaxial loading to be interpreted against a measure of its initially homogenous state.

Nearfield development of the negatively buoyant Rhône River inflow into Lake Geneva as an interflow: suspended particulate matter and associated fluxes.

2021 ◽  
Author(s):  
Violaine Piton ◽  
Frédéric Soulignac ◽  
Ulrich Lemmin ◽  
Graf Benjamin ◽  
Htet Kyi Wynn ◽  
...  
Keyword(s):  
Particle Size ◽  
Particulate Matter ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Suspended Particulate Matter ◽  
Fine Particles ◽  
River Plume ◽  
Lake Geneva ◽  
Suspended Particulate ◽  
Negatively Buoyant

<p>River inflows have a major influence on lake water quality through their input of sediments, nutrients and contaminants. It is therefore essential to determine their pathways, their mixing with ambient waters and the amount and type of Suspended Particulate Matter (SPM) they carry. Two field campaigns during the stratified period took place in Lake Geneva, Switzerland, in the vicinity of the Rhône River plume, at high and intermediate river discharge. Currents, water and sediment fluxes, temperature, turbidity and particle size distribution were measured along three circular transects located at 400, 800 and 1500 m in front of the river mouth. During the surveys, the lake was thermally stratified, the negatively buoyant Rhône River plume plunged and intruded into the metalimnion as an interflow and flowed out in the streamwise direction. Along the pathway, interflow core velocities, SPM concentrations and volumes of particles progressively decreased with the distance from the mouth (by 2-3 times), while interflow cross sections and plume volume increased by 2-3 times due to entrainment of ambient water. The characteristics of the river outflow determined the characteristics of the interflows: i.e. interflow fluxes and concentrations were the highest at high discharge. Both sediment settling and interflow dilution contributed to the observed decrease of sediment discharge with distance from the mouth. The particle size distribution of the interflow was dominated by fine particles (<32 μm), which were transported up to 1500 m away from the mouth and most likely beyond, while large particles (>62 μm) have almost completely settled out before reaching 1500 m. </p>

The Effects of Surfactants on the Granularity of the HA Powder Synthesized by Mechanochemistry

2009 ◽  
Vol 610-613 ◽  
pp. 1323-1326
Author(s):  
Tao Yu ◽  
Jian Dong Ye ◽  
Ying Jun Wang
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fine Particles ◽  
Low Cost ◽  
Sodium Hexametaphosphate ◽  
X Ray Diffraction ◽  
Laser Scattering ◽  
X Ray ◽  
Batch Sizes

The hydroxyapatite (HA) was synthesized by wet mechanochemical method；the effects of surfactant, such as triethanolamine, polyethylene glycol (200000), sodium hexametaphosphate, polyvinylpyrrolidone (K30), on the particle size distribution of as-prepared HA powder were studied. Results were characterized by means of X-ray diffraction (XRD), Scanning electron microscopy (SEM), Laser Scattering Particle Size Distribution Analyzer. The results show that the addition of surfactants eliminated the agglomeration of the powder and the uniform, fine particles (D10=0.1149μm, D50=0.12551μm, D90=0.1481μm) were obtained with the Triethanolamine (6 wt %) and Sodium hexametaphosphate (4 wt %) respectively. Our work demonstrates applicability of the mechanosynthesis for reproducible and low-cost synthesis of uniform, fine HCA powder in large batch-sizes.

Red Mud Powders Applied on Filling Rubber Composite Material

2013 ◽  
Vol 821-822 ◽  
pp. 1223-1226
Author(s):  
Yong Guang Fang ◽  
Zheng Ke Chen ◽  
Yu Qian
Keyword(s):  
Particle Size ◽  
Composite Material ◽  
Particle Size Distribution ◽  
Fluorescence Spectroscopy ◽  
Size Distribution ◽  
Red Mud ◽  
Fine Particles ◽  
Rubber Composites ◽  
Rubber Composite

Red mud is a kind of fine particles which with a strong alkalin value. The paper used red mud powder to prepare red mud-rubber composite for the feasibility of recycling about red mud. XK-160 open-mixing machine, QLB Series vulcanizing machine, multifunction electronic tensile machine, JC-1086 rotary roller, fluorescence spectroscopy analyzer, BT-9300 laser particle size distribution analyzer etc were used for test. The results showed that red mud in rubber composites played as beneficiations added in rubber significantly.

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