Fines Content Research Articles

Undrained shear strength of soils with fine fraction content derived from compression and extension loading triaxial tests

In the stability analysis of dams or deep excavations a calculation scheme of soil response is assumed that considers the rotation of main stresses. In the case of tailings dams constructed of granular material with fine fraction content (FC <0.075 mm), an additional factor is to be considered i.e. liquefaction phenomenon. Soil response to undrained shearing in compression loading (increase of vertical stress) and extension loading (increase of horizontal stress) differs significantly, giving various strength values. The paper presents the results of triaxial tests carried out on soils with fine fraction content. The tests were performed under compression loading and extension loading conditions. The test results’analysis was performed, considering grain size impact and main stresses application method at the shearing stage.

Evaluation of intermixing application of geotextiles at subgrade-base interface using accelerated pavement testing

This study focuses on identifying and quantifying the potential benefits of a geotextile separator in flexible pavements placed at the interface between a granular base and an underlying soft subgrade with high water content and a granular base. While benefits of using separators in roadway applications have been generally acknowledged, quantification of such benefits has been limited. The evaluation in this study is based on the results from two accelerated pavement tests using a one-third scale Model Mobile Load Simulator (MMLS3) device. Both models have identical configuration except that a non-woven geotextile was placed at the interface between the subgrade and base layer to serve as a separator in one of the pavement models. The subgrade material used in this study involved a soil mixture containing fifty percent kaolin and fifty percent Monterey sand #30. The base material was an angular AASHTO #8 aggregate. Additionally, an instrumentation program was implemented involving sensors to track the earth pressure distribution, the subgrade excess pore pressures generation, the change in moisture content of the subgrade and the horizontal particle displacement of the base layer. During exhumation of the pavement models, base and subgrade samples were collected to quantify the levels of intermixing. The results of the APT were quantified in terms of the traffic benefit ratio (TBR), which was as high as 6.4 for 25.4 mm rutting showing the significant benefit of using a non-woven geotextile as a separator to extend the design life of flexible pavements. The differences in performance observed between the control and the separation pavement models were found to correlate well with the amount of intermixing observed at the interface between subgrade and base layers. A series of soil columns were tested using cyclic loading to extend the intermixing analysis to different subgrade types with different fine content and geotextiles. The study concluded that higher levels of fine contain in the subgrade would lead to higher levels of intermixing. A correlation between the pore size of the geotextiles and the pumping of subgrade into the base was identified suggesting that smaller pore size would mitigate the pumping intermixing mechanism more efficiently.

Evaluating The Influence of Fines on the Characteristics of Pervious Concrete

Pervious concrete, also known as no-fines, gap-graded or porous concrete has an interconnected pore structure that freely allows the passage of water to flow through, thereby draining all or most of the water falling on its surface. This concrete can be used as paving material to reduce the storm water runoff to the drainage system and minimize water logging problems. In general, the porosity is achieved by omitting fine aggregate completely. But this results in a low strength concrete which cannot be used for most pavement applications. In this study, pervious concrete mixes have been formulated with a limited quantity of fines (10% and 20%) and the strength and permeability properties have been investigated for various types of fines (quarry dust, river sand and M-sand). While the strength of pervious concrete is increased considerably by adding fines to them, the permeability of the samples remains within the required range of 0.5 to 40mm/s. It has been observed that the addition of different types of fines had great influence in strength and permeability. The compressive strength increases with increase in fine content. Also, it is found that the compressive strength of cube with Quarry dust gives more strength compared to other fines.

Effect of Fine Aggregate Content on Performance of Pervious Concrete

Effect of Fine Aggregate Content on Performance of Pervious Concrete

Non-shrink, self-flowing dry mortar with a compressive strength of over 80 MPa using fine blast furnace slag

Non-shrink self-flowing dry mortar is commonly used in Vietnam to repair hollow, damaged concrete structures, or fill structural gaps. The manufacturing of non-shrink self-flowing mortar requires the use of many different types of additives. In addition, it is difficult to combine them to meet both technical and economic requirements. This article presents the results of research on producing non-shrink self-flowing dry mortar using fine blast furnace slag with a compressive strength after 28 days of over 80MPa. The input materials were all selected in dry powder form. The water/mortar ratio was 0,13. The fine blast furnace slag contents used were 15%, 20%, and 25%, and the powdered polycarboxylate superplasticizer was used at a content of 0.23% compared to the binder. In practice, the amount of water and superplasticizer must be chosen to maintain stability for the workability of dry mortar. The experimental results on flow, compressive strength, flexural tensile strength, and shrinkage show that the non-shrink self-flowing dry mortar meets the requirements of packaged dry mortar.

Micromechanism and mathematical model of stress sensitivity in tight reservoirs of binary granular medium

Research on reservoir rock stress sensitivity has traditionally focused on unary granular structures, neglecting the binary nature of real reservoirs, especially tight reservoirs. Understanding the stress-sensitive behavior and mathematical characterization of binary granular media remains a challenging task. In this study, we conducted online-NMR experiments to investigate the permeability and porosity evolution as well as stress-sensitive control mechanisms in tight sandy conglomerate samples. The results revealed stress sensitivity coefficients between 0.042 and 0.098 and permeability damage rates ranging from 65.6% to 90.9%, with an average pore compression coefficient of 0.0168–0.0208 MPa−1. Pore-scale compression occurred in three stages: filling, compression, and compaction, with matrix pores playing a dominant role in pore compression. The stress sensitivity of binary granular media was found to be influenced by the support structure and particle properties. High stress sensitivity was associated with small fine particle size, high fines content, high uniformity coefficient of particle size, high plastic deformation, and low Young's modulus. Matrix-supported samples exhibited a high irreversible permeability damage rate (average = 74.2%) and stress sensitivity coefficients (average = 0.089), with pore spaces more slit-like. In contrast, grain-supported samples showed low stress sensitivity coefficients (average = 0.021) at high stress stages. Based on the experiments, we developed a mathematical model for stress sensitivity in binary granular media, considering binary granular properties and nested interactions using Hertz contact deformation and Poiseuille theory. By describing the change in activity content of fines under stress, we characterized the non-stationary state of compressive deformation in the binary granular structure and classified the reservoir into three categories. The model was applied for production prediction using actual data from the Mahu reservoir in China, showing that the energy retention rates of support-dominated, fill-dominated, and matrix-controlled reservoirs should be higher than 70.1%, 88%, and 90.2%, respectively.

Effects of fines content on uplift behavior of underground structures in liquefied ground

Effects of fines content on uplift behavior of underground structures in liquefied ground

Optimum Fines Content in Manufactured Sand for Best Overall Performance of Superplasticized Concrete

Optimum Fines Content in Manufactured Sand for Best Overall Performance of Superplasticized Concrete

Estimation of the soil cyclic resistance by flat dilatometer accounting for the fines content effect

Estimation of the soil cyclic resistance by flat dilatometer accounting for the fines content effect

Study of Sediment Deposit Characteristics based on Geotechnical Properties and Geographic Information System (GIS) Approaches

Several sedimentation processes occur in the downstream area between river mouths and the sea. One of the effects of this sedimentation process is the occurrence of siltation around the coast. Not infrequently, this disrupts sea passages when the ship is about to head to the pier or go to sea. Kuala Beach is one of the locations in Pangkalpinang where the sedimentation process continues to occur enough to disrupt the smooth flow of sea traffic. This study aims to provide an overview and analysis of results related to sediment characteristics, spatial analysis of deposits, and predictions of deposition rates around Kuala Beach, Pangkalpinang City. This research was conducted using the following methods: 1) Method of investigating sediment characteristics by collecting data through field testing in the form of hand drills and laboratory testing, 2) Spatial analysis method by mapping the area of sedimentation based on the results of sediment characteristic tests using Agisoft Metashape and QGIS. The results of this study note that sediment deposits are dominated by sediments with sandy grain characteristics (SP symbol based on the Unified Soil Classification System) and a fine grain content (passing sieve number 200) of around 1-3%. The pattern of distribution of sediment deposits is known to have relatively flat contours and relatively uniform characteristics down to a depth of 1.5 m. The coefficient of grain uniformity (Cu) is in the range of 2.43-8.2 with the tendency of uniformity level getting higher to the southeast. The coefficient of grain gradation (Cc) is in the range of 0.44-1.64 with the tendency of the gradation level getting better to the southeast.

Bacteria Pseudomonas taiwanensis as a decomposing agent of peat fiber

Efforts are needed to accelerate the decomposition of peat fiber to reduce the fiber content through bioaugmentation using Pseudomonas taiwanensis bacteria so that it can reduce the high-water content of peat fiber. The research aimed to determine the effect of adding Pseudomonas taiwanensis bacteria on the decomposition of peat fiber. This research is a laboratory experimental research. The research sampling location was in Bereng Bengkel Village, Palangkaraya. The parameters observed included fiber content, fiber size distribution, and peat fiber decomposition speed following the Peat Testing Manual. The research instrument was an observation sheet for fiber content, size distribution, and peat fiber decomposition speed. Research data was analyzed using descriptive statistical analysis. The results showed that adding 15% Pseudomonas taiwanensis bacteria with a curing period of 28 days in fibrous peat resulted in the highest reduction in fiber content, from the initial condition of 61.14% to 12.33%. This variation also shows a decrease in coarse and medium fiber content and a significant increase in fine fiber content. The decomposition rate for this variation shows good consistency. The conclusion was that adding 15% Pseudomonas taiwanensis bacteria with a curing period of 28 days showed optimal results in accelerating the decomposition of peat fiber through the bioaugmentation method.

CBR Correlation with Index and Compaction Properties of Soil

California Bearing Ratio (CBR) is widely used in the design of roads to indicate the bearing capacity of subgrade as well as each layer of the flexible pavement system. However, the procedure for obtaining the CBR value is often considered complicated and time-consuming, thus; some correlations were developed by previous researchers between the CBR value and index properties such as fine content (w), liquid limit (LL), and plasticity index (PI) of the soil, as well as between the CBR value and compaction properties i.e., optimum moisture content (OMC) and maximum dry density (MDD). This study was conducted to evaluate the applicability of the published correlation on the soil obtained in Palembang and the surrounding areas. In this case, 30 sets of secondary data were collected and selected from past projects. In addition, laboratory tests were conducted on five sets of samples for verification purposes. The laboratory tests include a wet sieve to obtain fine content, Atterberg limits to determine soil’s plasticity, and a standard Proctor test to obtain OMC and MDD. Analysis shows that with modifications, some published correlations could be used to predict unsoaked and soaked CBR values for soils in Palembang. Furthermore, two correlations were developed between the CBR values and compaction properties of the soil based on statistical analysis of the collected data.

Seepage deformation characteristic of gap-graded coral sand in the South China Sea

Foundation settlement and collapse disasters resulting from seepage deformation in hydraulic-filled islands and reefs have been observed in the South China Sea, but the underlying failure mechanism and characteristic remain unclear. This study aims to investigate the influence of compactness and fine particle content on the seepage deformation of gap-graded coral sand and revel the characteristics and mechanism of seepage deformation of gap-graded coral sand through laboratory seepage deformation tests. The results indicate that the seepage deformation failure mode of gap-graded coral sand is influenced by the content of fine particles which undergo an evolution process from continuous piping to discontinuous piping to boiling. Particle loss is affected by the constraints between coarse particles, and the ability of different particle contact forms to restrict the loss of fine particles is different. Moreover, irregular particle morphology increases intergranular constraints, enhancing the coral sand's resistance to seepage deformation compared to standard quartz sand. Based on these findings, the instability coefficient was used to consider the influence of particle morphology and inter-particle contact on the seepage deformation. A hydraulic criterion for the internal stability of coral sand was established, demonstrating its versatility. Furthermore, the applicability of existing geometric criteria in evaluating coral sand was analyzed. The existing methods were found to be inaccurate in evaluating the internal stability of coral sand specimens with a fine particle content below 20 %.

Ground Improvement and Monitoring for a Reclamation on Reclaimed Soft Soil in Singapore

Land reclamation works for land development and harbor construction generally require large amounts of sand. At the same time the dredging of access channels, berth pockets and turning circles for shipping may generate both, ‘suitable’ and ‘unsuitable’ dredged sediments. The definition of suitable in general focusses on well compactable granular material with a low fines content. However, in the present times of environmental awareness and search for sustainable solutions, the offshore dumping and disposing of ‘unsuitable’ fine-grained material is not deemed sustainable anymore. In this paper the Tuas Terminal Phase 1 (TTP1) in Singapore will be discussed. All dredged soft clay and residual soils were used in the reclamation and capped with a layer of limited thickness of clean sand. To achieve the design requirements, ground improvement by means of surcharge with prefabricated vertical drains (PVD’s) was performed. To demonstrate the effectiveness and results of the ground improvement works, extensive monitoring by means of settlement beacons and clusters of extensometers and porewater pressure meters was setup. Even on-site developed ‘floating’ piezometers were developed to monitor the consolidating slurry. The execution of these works required adapted execution and advanced design methods. The design and prediction of the behavior of the sediments during improvement and on the long term was a challenge. The correct prediction of deformations and the level of the soft soil-granular soil interface was important to guarantee the correct sand cap thickness after ground improvement. The long-term behavior after overconsolidation through ground improvement was studied in detail. This has led to the development of a more correct prediction method to estimate the secondary settlements of PVD-improved overconsolidated soft soil. The reclamation of the TTP1 terminal proved to be a success where stringent design requirements were met while re-using ‘unsuitable’ material and minimizing the import of clean sand.

Influence of Fines Content and Pile Surface Characteristics on the Pullout Resistance Performance of Piles.

In this study, the direct shear test and model pullout test results are presented to assess the impact of soil fines content and shear resistance characteristics of the pile-soil interface on the pullout resistance of drilled shafts. The direct shear test on the soil-pile interface was conducted based on the pile surface simulated using sandpaper with three roughness types (#24, #40, and #400) and varying fines content. The direct shear test results of soil showed that the internal friction angle decreased by about 29% and the cohesion increased by about 110% when the fine powder content increased from 5% to 30%. Specifically, in the case of soil-sandpaper (#24), the interface friction angle decreased by about 31%, and the adhesion increased by about 16%. The sandpaper with a roughness of #40 and #400 also showed a similar trend. Normalizing the shear strength parameters from the direct shear test demonstrated an intersection between the normalized curves of the friction angle and cohesion (or adhesion) within a specific fines content range. This suggests that shear strength parameters play a significant role based on fines content. Analyzing the normalized index using model pullout test results indicated the necessity to evaluate the contribution of friction angle and cohesion (or adhesion) of the shear surface, taking into account the fines content of the soil for predicting pile pullout resistance.

Experimental study on monotonic to high-cyclic behaviour of sand-silt mixtures

The naturally deposited soil usually does not consist of pure coarse or fine-grained soil but of a mixture of both. The mechanical behaviour of a saturated fine sand mixed with varying amounts of low-plastic fines was evaluated by monotonic as well as high-cyclic triaxial tests. The test results were used to conclude on the effect of fines content on the critical state, phase transformation line, secant Young’s modulus, the residual strain accumulation as well as strain amplitude during drained cycles of the mixtures in relation to the global void ratio as well as to the equivalent void ratio. It was found that while the choice of void ratio definition is important for the uniqueness of the critical void ratio, both approaches can be used as state variables for the phase transformation line. However, some seemingly contradictive results are found from the drained high-cyclic tests. Eventhough, an increase of the residual strain accumulation with decreasing fines content compared at the same initial equivalent void ratio is rendered by the laboratory data, a unique and on fines content independent relationship between εacc\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varepsilon ^{\\rm{acc}}$$\\end{document} could be established only with respect to the initial global void ratio.

Geotechnical Suitability of Soils in Road Construction for Sustainable Development in Tropical Africa: Case of Lateritic Graveled Soils of Bandjoun (West, Cameroon)

The environmental impact of the exploitation of geomaterials and their relatively high cost, coupled with the increasingly low financial capital in developing countries, are pushing road actors to turn to inexpensive local ecological materials. The present study is conducted on lateritic graveled soils of Bandjoun (LGSB) in the West Cameroon Region. The aim is to determine whether lateritic gravel soils, particularly those in Bandjoun, can be an ecological and economical alternative to rock aggregates in road construction, considering their geotechnical parameters and environmental impact. These soils were described in the field and were also subjected to complete geotechnical identification in the laboratory. The LGSB presents Californian bearing ratio indices ranging from 26% to 83.3%, a plasticity index of 10.11%, a fines content of 12.05%, an average methylene blue value of 4.25, a water content at the Proctor optimum of 27.6% and a dry density of 1.75 g/cm3. They are silty or clayey gravels and sands of subgroup A-2-7 according to the Highway Research Board classification; sandy and gravelly soils with fines of class B according to the classification of the Road Construction Guide; and silty gravels according to the classification of the Central Laboratory of Bridges and Highways. These soils can be used naturally in pavement layers, in particular in subgrade for all traffic classes and in subbase for low traffic. The tonnage of these soils has been estimated at 18,389 t. The global warming index shows that the use of these soils (18,389 t) in road construction can reduce 31,629–62,706 kg of carbon emissions. The use of lateritic soils in road construction is a very interesting alternative to reduce the environmental impacts associated with the manufacture of rock aggregates. So, lateritic soils should be used instead of rock aggregates for cleaner, more environmentally friendly road construction. The present work presented a specific evaluation of the geotechnical properties and ecological impact of lateritic graveled soils for road construction, as well as their potential for ecological and economic utilization.

Effect of steady-state strength of medium to dense sand on the performance of sheet pile wall as identified through centrifuge tests and Type-B and C simulations

This study focuses on five centrifuge experiments of a sheet pile wall performed by three institutions, which cover relative densities ranging from 55 % to 66 %. A strain space multiple mechanism model incorporated in the computer program FLIP is used for the simulation. In the Type-B simulation performed before the centrifuge test data release, the steady-state strength Sus is not considered, i.e., Sus is assumed to be infinity (Sus=∞), and only cyclic resistance is considered. In the Type-C simulation performed after the release of the centrifuge test data, Sus and cyclic resistance are considered. When Sus=∞, the computed displacements of the sheet pile wall are consistent with or unconservative by a factor of one-half of the measured displacements. However, when Sus ranges from 1500 to 7500 kPa evaluated for clean sands, the computed displacements are generally consistent with the measured displacements, or slightly conservative. When Sus ranges from 100 to 400 kPa evaluated for sands with fines content of 5 %, or when Sus ranges from 20 to 50 kPa inferred from cyclic laboratory tests, the computed displacements are conservative by a factor of one and a half or two of the measured displacements. The steady-state strength of medium to dense sand is identified as a significant factor influencing the performance of a sheet pile wall.

Effect of Size-Distribution Environment on Breakage Parameters Using Closed-Cycle Grinding Tests.

The so-called population balance model (PBM) is the most widely used approach to describe the grinding process. The analysis of the grinding data is carried out using-among others-the one-size fraction BII method. According to the BII method, the breakage parameters can be determined when a narrow particle size fraction is used as feed material to the mill. However, it is commonly accepted that these parameters are influenced by changing the particle size distribution in the mill. Thus, this study examines the breakage parameters through kinetic testing in different natural-size distribution environments generated by closed-cycle grinding tests that simulate industrial milling conditions. The differentiation of the milling environments was accomplished using various reference sieves in the closed-cycle tests. The experimentally determined breakage parameters were back-calculated and then used to simulate the closed-cycle tests using the MODSIMTM software. Additionally, the energy efficiency was evaluated based on the specific surface area of the grinding products and the energy consumption. The results of the kinetic tests showed that the breakage rate of the coarse particles increases as the aperture size of the reference sieve decreases, and consequently, the content of fines in the mill increases. The back-calculated breakage parameters can be reliably used to simulate closed-cycle circuits, thus helping control industrial milling operations.

Modelling and validation of liquefaction potential index of fine-grained soils using ensemble learning paradigms

This study explores the utilization of ensemble-based soft computing techniques for predicting the liquefaction potential of fine-grained soils. Generally, deterministic methods are used to assess the possibility of liquefactions. However, recent advancements have highlighted the implementation of machine learning techniques considering the diverse geotechnical characteristics for liquefaction susceptibility analysis. The current study predicts liquefaction potential index (LPI) of soils using five ensemble-based soft computing paradigms viz., decision tree, random forest, gradient boosting, AdaBoost, and XGBoost regressors. Various influential factors including stress parameters, depth of soil stratum, peak ground acceleration, earthquake magnitude, cyclic stress ratio, fine content, and SPT- N value, were used for estimating the LPI of soils. Experimental results of the employed models were assessed using multiple statistical indices. The results demonstrate that the employed XGBoost model achieved higher predictive accuracy with 99 % accuracy (based on R2 index) during the testing phase. Overall results exhibit that the employed XGBoost paradigm can be utilized as a viable alternative to empirical approaches, enabling an early assessment of liquefaction susceptibility in different engineering projects. This will expedite identification and evaluation of liquefaction hazards, allowing engineers to make more informed decisions.