Percentage Of Fines Research Articles

Experimental Research on Effect of Fines Content on Liquefaction Properties of Sand

Liquefaction is a phenomenon mainly occurred in saturated fine grained soils under major earthquakes causes tremendous loss to infrastructure. From the literature it has been observed that liquefaction not only occurs in fine sands but also occurs in sands containing some amount of fines particles, which are of less than 75µ in size. Unfortunately there is no clear conclusions given as how effect the fines content on liquefaction resistance of sandy soils. In order to solve above mentioned problem this study was undertaken through stress-controlled cyclic triaxial tests to know the effect of fines content on liquefaction resistance of sandy soils. In this study the program of experimentation was done on base sand and sand mixed with four different combinations of fines like 10%, 20%, 30%, and 40% of fines with base sand by weight.. The main parameters changed in this work were percentage fines and shear stress ratio (CSR ), where the observed parameter was amount of pore water pressure and cycle of loading.. The result showed that, rate of pore water pressure generation during cyclic loading was largely affected by limiting silt content and density index. The trend observed as amount of pore water pressure is increased more than base sand with adding of fines content up to 20%, later the trend observed as reverse. And also noticed that more CSR value increases the pore water pressure generation and decreases the cyclic resistance

The integration of grain-size distribution and plasticity parameters for characterizing and classifying unconsolidated fine-grained sediments

Grain-size distribution (GSD) characteristics are often used to classify different types of sediment and to understand how variations in depositional processes affect mechanical behavior. However, the current grain-size-based classification systems have not been able to distinguish fine-grained sediments with varying silt and clay content. In addition, the current classification systems do not consider mineralogy in the classification scheme or the subsequent implication of mineralogy in the mechanical behavior of the sediment. This study proposes a new grain-size-based scheme to classify unconsolidated inorganic sediments that cover a wide range of natural depositional environments with a special emphasis on fine-grained deposits. The proposed classification assumes a linear relationship between percent fines and the silt fraction. This relation describes the behavior of the GSD curve, which analysis showed to be controlled by the ratio of the clay fraction to the silt fraction. The proposed scheme allows the clay mineral composition to be included, and allows the mechanical behavior to be inferred as well. The classification scheme shows that plasticity indices (i.e. liquid limit and plasticity index) are reliable proxies for clay mineralogy. In addition, the study uses the activity of clay as a quantifiable factor that discriminates between the major clay-mineral groups. By combining grain-size characteristics and plasticity, the proposed classification extends the utility of the scheme beyond simply classifying the sediment class, towards inferring the potential mechanical behavior of sediments having various GSD characteristics and mineralogy.

Modeling resilient modulus of fine-grained materials using different statistical techniques

For the realistic prediction of pavement performance, it is very important to accurately characterize the mechanical behavior of unbound material layers and subgrade soils. In pavement analysis using the elastic layered theory, material properties in terms of dynamic elastic modulus and Poisson’s ratio are the major input parameters. The dynamic elastic modulus of pavement materials or resilient modulus (MR) is measured by conducting repeated load triaxial compression tests typically not available to highway authorities due to the high costs involved in acquiring such high-performance equipment and/or lack of knowledge on how to operate this specialized equipment. Therefore, pavement engineers are obligated to use pavement design methodologies based on empirical tests. The main objective of this study is to use multiple linear regression (MLR), nonlinear regression and backpropagation artificial neural network algorithms to develop models to predict the resilient modulus of fine-grained materials based on 3709 soil samples collected from the Long-Term Pavement Performance (LTPP) website. The key input parameters selected for this study are: the confining pressure (σ3), nominal maximum axial stress (σ1), percent of silt (S), Liquid Limit (LL), Plasticity Index (PI), percent passing number 200 sieve (P#200), maximum dry density (ρmax-dry), percent of clay (C), optimum moisture content (wopt), and laboratory-determined resilient modulus. Results revealed that the change of wopt has a higher effect on MR compared with the change in density, the percent fines, percent of silt, percent of clay, confining pressure, PI and LL but less than the effect of changing axial stress. In addition, the best modeling technique to predict the resilient modulus of fine-grained soil was found to be the Artificial Neural Network (ANN) followed by the nonlinear regression and finally the MLR.

Effect of Crushing on Stress–Strain and Pore Pressure Behavior of Micaceous Kutch Soil Under Monotonic Compression and Repeated Loading–Unloading Conditions

Mica particles are flaky and layered in nature with relatively low hardness as compared to quartz particles. Micaceous soil with more than 10% mica is generally not recommended for pavements due to low compactability and high resilient nature. Limited research has been performed on shear strength behavior of micaceous soils at varying mica contents with no crushing effect. The current research is focused on the effect of crushing on compactability, compressibility and shear behavior of naturally available micaceous Kutch soil with mica content of 14% under different loading conditions. Soil specimens with different degree of crushing (S0–S6) are prepared by applying repeated impact loading cycles. A comprehensive experimental study is conducted on these specimens to evaluate the effect of crushing on shear behavior of micaceous Kutch soil under monotonic compression and repeated loading–unloading conditions. The monotonic shear response depicted reduced peak stress and increased contractive response with higher degree of crushing. However, the shear response under repeated loading–unloading conditions exhibited higher irrecoverable plastic strain accumulation with increase in crushing cycles. This could be due to the decreased resilient nature of mica particles and increased percentage of fines at greater degree of crushing.

Characterisation of crushed base for mechanistic-empirical pavement design guide

This paper describes a recently completed laboratory test programme to determine the standard properties of crushed base aggregates collected from 14 road projects throughout Wyoming. Eleven of 14 base aggregates were selected for resilient modulus testing performed in accordance with the Wyoming modified AASHTO T 307 procedure. Effects of moisture content, percent fines content, stresses, and gradation on base resilient modulus were assessed. Models were developed using statistical methods to estimate the resilient modulus of base materials. The NCHRP and Hicks and Monismith constitutive models were calibrated. A design chart of resilient modulus in terms of asphalt thicknesses was established to facilitate the iterative process involved in a pavement design. Finally, a design table of base properties for MEPDG Level-3 inputs was developed to facilitate the full implementation of the MEPDG. The proposed framework for developing these methods could be adopted nationally to facilitate the full implementation of MEPDG.

Erosion Studies on Lithomargic Clays

Lithomargic clays are found at shallow depths in lateritic formations, sandwiched between hard lateritic crust at top and the parent granitic gneiss underneath. Many earlier studies have proved that the behaviour of these soils is similar to dispersive soils, and they are also found to be highly erosive. Very few and detailed studies on erosion of lithomargic clays are available in the literature. Lithomargic clays along the western coastal belt of peninsular India are available with varying percentages of sands and fines (especially silts, with negligible amount of clays occasionally). In this study, a number of hole erosion tests are conducted on controlled lithomargic clay samples with varying percentage of fines to study their erosion characteristics. The influence of degree of compaction, moulding water content, head causing flow, percentage silt content and plasticity index on the erosion rate index and critical shear stress of controlled lithomargic clay samples are being studied. The results of this study indicate that the critical shear stress for soils with higher silt fraction and fine sand content varied from 45 to 125 N/m2, whereas for soils with higher clay fraction and fine sand content the critical shear stress varied from 200 to 400 N/m2. The erosion rate increased with a decrease in percentage compaction in all the samples, and critical shear stress is found to be highest at optimum moisture content conditions. It is generally observed that soils with fines whose plasticity indices are high, are less erodible compared to soils with fines whose plasticity indices are low.

Mortality and Early Feeding Behavior of Female Turkey Poults During the First Week of Life.

Turkey poults are susceptible to early mortality and poor initial feeding behavior for reasons that are not well-understood. This study was conducted to investigate the relationship between the development of turkey poult feeding behavior and early mortality, with a focus on the effect of biological age and diet. We hypothesized that increasing biological age would increase mortality, and that poults that had earlier feeding behavior would have decreased mortality. Nine hundred and sixty female turkey poults were randomly assigned to 24 pens (40 poults per pen). The study was conducted as a completely randomized block design with a factorial arrangement of two ages (early and standard hatch) and three diets (control, modified A, and modified Ca/P B, differing primarily in the Ca/P ratio and percent fines). The behavior during the first 24 h after placement of newly placed poults was examined. Growth performance and mortality throughout the first week of life was also measured to determine if early behavior had any impact on these variables over time. Behavior during the first 24 h was similar between the age treatments; both spent ~2.5% of the time drinking, 7% of the time feeding, 12% of the time active and 80% of the time inactive/resting. There was no effect of diet or age treatment on latency to feed or drink. Growth variables were not affected by biological age. However, there was a significant diet and biological age effect on bodyweight and mortality. Standard hatch poults fed a control diet were lighter than other poults at 7 d, while standard hatch poults fed the diet with the lowest Ca:P had the highest mortality. For all treatments, early mortality was primarily due to yolk sac infection, although >1% of placed poults died due to starvation. Findings of the present study indicate that, regardless of biological age or diet, poults established feeding behavior within the first 24 h and the majority of early poult mortality under these experimental conditions was due to factors other than starvation.

Response of stone column-improved ground under c-ϕ soil embankment

Problems with stone column-supported embankments are often addressed considering the pure granular soil properties of the embankment material. In practice, however, the embankment material may contain a certain percentage of fines which makes the material c-ϕ in nature. In the present paper, experimental and 3D numerical studies are conducted to investigate the effect of the fines content present in the embankment soil on the response of a stone column-improved ground. The numerical study is carried out using the finite difference software package FLAC3D. The time-dependent behavior of the improved soil is modeled. It is observed that an increase in the fines content in the embankment soil brings about a decrease in the stress concentration ratio and an increase in the vertical displacement and the pore pressure in the soft soil. However, the vertical displacement of the soft soil does not change significantly above a fines content of 20%. The lateral displacement of the stone column increases at the top with an increase in the fines content and the point of the maximum lateral displacement shifts in the downward direction. It is also observed that the differential settlement increases at the ground level as well as at the embankment top with an increase in the quantity of fines in the embankment soil. Thus, the critical height of the embankment (a height where no differential settlement occurs on the embankment surface) increases due to the increase in the fines content.

The influence of pipe embedment material on sinkhole formation due to erosion around defective sewers

Abstract Internal erosion through leaking sewers causes sinkholes in the non-karstic ground. As erosion resistance depends on particle-size distribution, improved erosion resistance of pipe embedment by modifying its gradation is worth study. This paper reports on physical model tests simulating erosion and sinkhole development due to cyclic leakages through defective sewers for five selected grading curves compatible with the Sewerage Code of Australia. Eroded soil mass, eroded soil properties, cavity initiation and evolution up to sinkhole failure were studied due to cyclic leakages through pipe cracks. Ground settlement during this process was also monitored using particle image velocimetry. Also, any potential to use existing geometric criteria which are proposed to assess internal stability in embankments to predict the risk of erosion through openings were also studied. Results indicate that poorly-graded sand with Dmax of 4.75 mm was highly susceptible to erosion through 10 mm wide cracks regardless of the fines percentage and the gradation. Remarkably, selected well-graded crushed rock with Dmax of 9.5 mm was highly resistive even through 30 mm wide openings. Modification of the existing standards for embedment materials in the current standard is recommended and as fine soil can create sinkholes even due to small pipe defects, the use of well-graded coarse sand or fine-gravel with about 15–20% medium-sized gravel particles is recommended.

Enhancing dissolution of artesunate from immediate release tablets using a green granulation technique

Artesunate is a poorly soluble drug and liable to aqueous hydrolysis. This study aims to formulate Artesunate as an immediate release tablet through optimization of the melt granulation technique to improve the dissolution of the drug. Three different meltable binders were used (Polyethylene Glycol PEG 6000, Poloxamer 188 and Gelucire 50/13) for granulation step in high shear mixer prior tablets compression step applying Box-Behnken experimental design to determine the significant variables and their interactions that impact dissolution of Artesunate. Optimization mathematical models showed that by increasing binder concentration, D50 was increased, and narrow particle size distribution with minimum fines percentage was produced. Higher binder concentration and impeller speed resulted in retarding tablets dissolution. PEG 6000 and Poloxamer 188 based tablets showed faster disintegration and dissolution than Gelucire 50/13 based tablets, as well as tablets prepared by wet granulation due to hydrophilic pore forming. Melt granulation technique using a low level of PEG 6000 and Poloxamer 188 not only enhanced the dissolution of Artesunate from their immediate release tablets in comparison to traditional wet granulation technique but also maintained the stability of the product under accelerated conditions of heat and moisture.

Fines quality assessment in all-in aggregates for pavement layers related to different standard procedures

During the construction of the unbound pavement layers of Corridors X and XI in Serbia, a problem was detected regarding the evaluation of cleanliness of the available materials. The European standard for the sand equivalent from 1999 to 2015 had significant changes related to the test procedure. A mass correction has been taken into account. It consists of replacing a part of the fines with rinsed material (0.063/2 mm) when the percentage of fines exceeds 10% in a tested fraction. Thus, the test sample usually yields high values of the sand equivalent, which often exceeds the limits of 50% and 60%. From the standpoint of the technical specifications, aggregates are considered clean, while using other methods like methylene blue or a plasticity index, the presence of clay particles above the limits can be confirmed. This paper presents the results of research on 63 laboratory-prepared test samples of limestone aggregate with small quantities of the smectite group of clay minerals, where the fines content in the unbound aggregate, 0/31.5 mm, gradually increased up to 20%. It was found that the sand equivalent values are continuously decreasing from 84 to 14% in the fraction 0/2 mm and from 87 to 18% in the 0/4 mm fraction, with increasing of the methylene blue value of the all-in aggregate (MBA) from 0.4 to 4.5 g/kg. Correlations of different methods and fractions, as well as with the content of fines were found. There are no correlations with SE10 because of grouping the test data around one point.

Suitability of sands from different locations at Nsukka as backfill material for vibroflotation

Soil stabilization using vibroflotation method requires material backfill for smooth operation of the process and effective densification. Backfill materials fill the voids created by the vibroflot and acceptable backfill is sand with less percentage of fines. This study assesses the suitability of Nsukka sand for backfill purpose in vibroflotation. Samples of Nsukka sand were tested in the laboratory for their physical, mechanical and electro-chemical properties. The suitability numbers (S N ) were determined and a linear regression analysis carried out to correlate the values of S N with the properties of the sand. Tests results showed that Nsukka sand is “Good” backfill material for vibroflotation with a mean S N of 15. The samples indicated narrow percentage of fines value of 0.34 - 4.81% and are generally classified as poorly graded sand (SP) with mean fineness modulus of 2.12. They have low salt content with electrical conductivity values between 1090 - 1950µS/cm and mean pH and chloride content values of 6.8 and 98.5ppm respectively. Dry compaction test reveals mean MDD value of 1809kg/m 3 for standard Proctor compaction. Linear regression analysis reveals that S N is dependent on D 10 and D 30 . The efficiency of the model was tested with separate results and the differences between the actual and the predicted S N were small and acceptable. This study concludes that Nsukka sand is a good material for vibroflotation densification. 14.00 Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Times New Roman,serif;} http://dx.doi.org/10.4314/njt.v37i4.2 14.00 Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Times New Roman,serif;} SUITABILITY OF SANDS FROM DIFFERENT LOCATIONS AT NSUKKA AS BACKFILL MATERIAL FOR VIBROFLOTATION 14.00 Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Times New Roman,serif;}

Determining the effects of depositional processes on consolidation behavior of sediment using shear-wave velocity

Compression behavior of sediments is crucial to geological engineering applications for ascertaining the deformation characteristics of the particular depositional environments. Unfortunately, obtaining the geotechnical parameters required to assess the compression behavior of sediments can be a costly and time-consuming undertaking. This study developed a general prediction equation that simulates the compression behavior of sediments. This developed equation is an exponential decline model that relates an increase of the shear-wave velocity to an increase of the mean effective stress. Consequently, the decrease of void ratio is presented as a continuous function of the shear-wave velocity. For this research, laboratory-derived sediment samples created to mimic actual sediments were isotopically consolidated during a consolidated undrained triaxial compression tests. The samples were prepared in the laboratory by mixing different percentages of fines and controlling the ratio of clay-to-silt fractions. Shear-wave velocity tests were performed during this consolidation testing using bender elements. The experimental constants needed for the prediction equation were well correlated to the depositional factors specifically characterized by percent fines, silt percent, and liquid limit that define better complexity of depositional processes.

The Use of Acoustic Emission to Detect Fines for Wood-Based Composites, Part One: Experimental Setup for Use on Particleboard

Wood-based composite panels continue to be important in the wood building industry. Particleboard is commonly used for non-structural applications, while oriented strand board (OSB) is commonly used for structural applications. For both types of boards, however, manufacturers are interested in minimizing the presence of small particles or “fines” in the panels. The presence of fines can cause an increase in the consumption of resins as well as an increase in the weight of the board. Fines can be produced when a refiner or chipper blade becomes dull or when the wood raw material becomes excessively dry. There is a need for manufacturers to simply and accurately monitor the presence of fines and control their presence. Acoustic emission (AE) is an elastic or plastic wave generated when a surface is deformed or has an external force exerted on it. This research showed the feasibility of using AE to monitor the presence and percentage of fines in particleboard furnish. The research also showed the effect of the experimental setup on the AE signal level.

The Use of Acoustic Emission to Detect Fines for Wood Based Composites, Part Two: Use on Flakes

Oriented strand board (OSB) is commonly used for structural applications. Manufacturers of OSB want to minimize the presence of small particles or “fines” in the panels because fines increase the consumption of resins, leading to an increase in the weight of the board. Fines are produced when either a refiner or chipper blade becomes dull, or when the wood raw material becomes excessively dry. By accurately monitoring the presence of fines, manufacturers can help control their percentage within a product. Acoustic emission (AE) is an elastic or plastic wave generated when a surface is deformed or has an external force exerted on it. This research shows the feasibility of using AE to monitor the presence and percentage of fines in flakes. The study follows up on previous research conducted years ago by Lemaster (1994). The study also shows the effect of the flake geometry and flake moisture on the AE signal.

Roller compaction: Improving the homogeneity of ribbon properties along the roller width

A new roller with a novel surface geometry was designed and used in this study in order to improve the uniformity of the stress distribution along the roller width. This was aimed to produce homogenous properties across ribbon width. The porosity distribution resulting from the applied stress, was correlated to the temperature distribution across the ribbon width using an online thermal camera. Using the new curved roller resulted in a significant improvement in the uniformity of the temperature across ribbon width. This is resulted in significant reduction in the fines percentage in the product and produced wider ribbon. The new curved roller was also produced better ribbon quality by decreasing the difference in the porosity between the centre and the side of the ribbon. Overall, the curved roller resulted in more homogenous properties across ribbon width in comparison to the standard flat roller.

Ribbon density and milling parameters that determine fines fraction in a dry granulation

A challenge in the dry granulation (DG) process is the generation of an excessive amount of fines during milling, which can cause problems in die filling due to poor flowability and content uniformity of tablets. Using a design of experiments (DOE) approach, we show that the amount of fines generated during milling decreases with either increasing ribbon density or screen size, while impeller speed has negligible effect. Moreover, under identical milling conditions, the percent fines can be accurately predicted from ribbon density. Thus, controlling ribbon density and screen size is important for optimizing the amount of fines produced during DG process. Because density has a central role in the outcome, it is a critical ribbon property that needs to be controlled to improve robustness of the DG process.

Application of deterministic and probabilistic ‐ SPT based liquefaction assessment triggering models

AbstractThis paper presents an application of the SPT based liquefaction triggering models (both deterministic and probabilistic) proposed by Boulanger and Idriss (2010). Several authors consider deterministic approaches to be beneficial in areas of high seismicity. The procedure for predicting probability of liquefaction however can be alternative tool of analysis that could complement the deterministic procedures by providing information on the relative risk of liquefaction between design alternatives. It is used to estimate the probability of liquefaction for a given design earthquake magnitude and acceleration. Both deterministic and probabilistic approaches were used for a liquefaction susceptible soil profile for different percentage of fines. The location is in Ohrid, as a specific area with high groundwater tables, complex geological conditions and medium level seismicity. The potential of liquefaction is determined for all layers of the soil. The results show that the probabilistic approaches shouldn't be excluded in this assessment and can be more favourable for areas of intermediate seismicity.

Evaluation of the mechanical properties and critical slope parameters of mine tailings at Enyigba, South eastern, Nigeria

This study examines the effects of slope geometry and Geo-mechanical parameters of tailing dumps at Enyigba mine, Nigeria. Fifty-two slopes were studied, with seven sampled for laboratory analysis. Correlation matrix and principal component analysis were employed in the data interpretations. The mechanical properties of the slope materials were investigated using geotechnical tests such as sieve analysis, Atterberg limits, compaction and undrained triaxial tests. Shear strength parameters generated from the triaxial tests were utilized in slope stability analysis executed with the Slope/W Geostudio software. Both statistical and slope stability methods suggested a combination of height and width (dimensions) has more significance on the stability of the dump slopes at Enyigba mine than slope angles (inclination). Height and width constituted 83.61% of the total variance data and represented 16.39%. Particle size distribution of the slope materials showed high percentage of fines. The computed factor of safety of the slopes ranged from 1.00 to 1.30, implying critical stability which indicates liability of the slopes to failure when predisposed to landslide triggering agents. Therefore, slope dimension optimization and stabilization are required on the tailing dumps at Enyigba to prevent severe landslide occurrence.

A critical state constitutive model for clean and silty sand

The mechanical behavior of silty sand is highly dependent on the percentage of fines in addition to the packing density and confining pressure. Properly modeling the diverse behavior of silty sand remains an area of difficulty and uncertainty. This paper presents an attempt to formulate a critical state-based constitutive model for sand with varying fines content based on several new laboratory findings. A marked feature of the model is a unified description of the state-dependent elastic modulus as well as a unified description of plastic hardening modulus such that only one set of elastic and hardening parameters is required for sand with different fines contents. The model is calibrated and validated using the results from a structured experimental program. It shows that the model can produce reasonably good predictions for undrained shear responses of sand specimens under a range of void ratios, confining stresses and fines contents. In particular, it successfully predicts the laboratory observation that under otherwise similar conditions, the presence of non-plastic fines increases the liquefaction susceptibility of sand.