Size Distribution Curves Research Articles

Surrogate models to predict maximum dry unit weight, optimum moisture content and California bearing ratio form grain size distribution curve

This study evaluates the applicability of using a robust, novel, data-driven method in proposing surrogate models to predict the maximum dry unit weight, optimum moisture content, and California bearing ratio of coarse-grained soils using only the results of the grain size distribution analysis. The data-driven analysis has been conducted using evolutionary polynomial regression analysis (MOGA-EPR), employing a comprehensive database. The database included the particle diameter corresponding to a percentage of the passing of 10%, 30%, 50%, and 60%, coefficient of uniformity, coefficient of curvature, dry unit weight, optimum moisture content, and California bearing ratio. The statistical assessment results illustrated that the MOGA-EPR provides robust models to predict the maximum dry unit weight, optimum moisture content, and California bearing ratio. The new models’ performance has also been compared with the empirical models proposed by different researchers. It was found from the comparisons that the new models provide enhanced accuracy in predictions as these models scored lower mean absolute error and root mean square error, mean values closer to one, and higher and coefficient of correlation. Therefore, the new models can be used to ensure more optimised and robust design calculations.

A study on the effect of pore and particle distributions on the soil water characteristic curve of compacted loess soil

Compacted loess soil is used as a geo-material in many engineering projects, such as building foundations and highway embankments. Water infiltration characteristics and post settlement of the compacted loess in large construction projects of Northwest China have received increasing attention from researchers and investors. These behaviors are closely related to the soil water characteristics. This study aims to investigate the soil water characteristic curves (SWCCs) of compacted loess soil with different dry densities and to reveal the responsible micro-mechanisms for soil water characteristics. Loess soil collected from the new district of Yan’an City, China, is prepared into five dry density groups. The SWCC of each group in the suction range of 0–105 kPa is measured using the filter paper method (FPM). Two-dimensional (2D) images and the pore size distribution (PSD) curves of the specimens are tested by scanning electron microscopy (SEM) and the mercury pressure method (MIP), respectively. The results of this study highlight that the compaction behavior mainly influences the pores with a radius (r) in the range of 1–10 μm, and has no influence on the pores of r < 0.5 μm. The particle shapes among the five dry densities groups are similar. The characteristics of the PSD curves of the compacted loess soil correspond well to the SWCCs. The suction of the SWCCs increases with increasing dry density in the lower suction range of 0–100 kPa. In contrast, suction among the five dry density groups is almost identical in the suction range exceeding 100 kPa. The results of the study are helpful to understand the SWCC and microstructure characteristics of compacted loess with different dry densities.

The use of particle size distribution integrated with consistency limits for experimentally simulating fine-grained sedimentary units

The current study hypothesizes that reproducing sediment units that might belong to areas difficult to reach, sample, and attest is experimentally possible. The research aims to employ available sediment samples named source soils that can easily approach and sample to mix, simulate, and produce the (non-available) sedimentary units named Target Sediment Units (TSU). The particle size distribution (PSD) percentages are essentially used in the mixture procedure to construct the non-available (target) units (TSU). Several sedimentary units were targeted, designed, and simulated; They include marsh, bay mud, and natural levee sediment units selected from the eastern Basrah side at the lower Mesopotamian plain, southern Iraq. The matching between particle size distribution (PSD) curves of simulated sediment units (SSU) and target sediment unit (TSU) was verified by applying a developed slope proximity ratio. For the three tested sediment units (marsh, buy mud, and natural levee), the ratios of slope proximity were 1.0, 0.93, and 0.99, respectively, which are well matched. For the mineralogy, the consistency limits were used as a proxy. The Casagrande plasticity chart was modified to reveal two empirical functions linking the plasticity indices to the clay mineral groups. The two predictions are reliable means to proxy the mineralogy of the fine-grained sediments. Reconstructing procedure allows the non-available sediment samples to be practically presented and it better characterizes the sediment for forensic geoscience applications; for instance, engineering geology and sedimentology applications concerning with studies of the physical and mechanical behaviors of sediments and the depositional conditions interpretations, respectively.

Prediction of Particle Size Distribution Curves of Dump Materials Using Convolutional Neural Networks

Prediction of Particle Size Distribution Curves of Dump Materials Using Convolutional Neural Networks

Heat-stimulated crystallization and phase transformation of titania nanoparticles

To better understand the fundamental aspects of nanoparticle formation and transformation in the TiO2-H2O system the amorphous titania was synthesized as a precursor to studying crystal genesis, evolution, and transformation under heat treatment in air. The necessary depth of study was provided by comprehensive analysis using methods of PXRD, HT-PXRD, DSC-TG, TEM, BET adsorption, and helium pycnometry. The smallest crystallite size of the anatase phase is shown to be defined by the size of the initial amorphous titania nanoparticles. The amorphous state of initial titania nanoparticles is stabilized by water molecules incorporated into their structure. The anatase-to-rutile phase transition occurs when the average crystallite size of the anatase reaches the value of 35–45 nm. An explanation for a drastic change of the average crystallite size during the anatase-to-rutile transition repeatedly found in researches is in the difference in shapes of curves of crystallite size distribution.

Electrospinning of Gelatin Nanofibers: Effect of gelatin concentration on chemical, morphological and degradation characteristics

Electrospinning is a well-known technique that produces polymeric nanofibers using an electrically driven jet of a polymer solution. Due to unique properties such as high surface area, porosity, tensile strength and extensibility of the materials produced by electrospinning, several applications of them in protective clothing, space technology, filtration and tissue engineering have been proposed and investigated. In this study; we prepared gelatin nanofibrous scaffolds by using the electrospinning method for tissue engineering applications. The beads-free, smooth and uniform gelatin nanofibers were successfully fabricated. The blend solutions at different weight ratios were prepared by dissolving gelatin in a solvent mixture containing formic acid, dichloromethane and acetic acid. The fabricated nanofibers were chemically crosslinked by glutaraldehyde vapor. The crosslinked nanofibrous scaffolds were characterized by chemical and morphological analysis. The morphology and size distribution curves of nanofibers were determined by Scanning electron microscopy (SEM). The chemical structure of nanofibers was investigated by Fourier transform infrared spectroscopy (FTIR) analysis. The strategy based on electrospinning of gelatin nanofibers can be used to develop new biomimetic materials for tissue engineering applications.

EFFECTS OF PARTICLES DISAGGREGATION UNDER ULTRASONIC-ASSISTED WATERFLOODING ON OIL RECOVERY

Ultrasonic waves have a wide variety of applications in a variety of fields. It is used in the oil and gas industry to remove near wellbore damage, and several studies have been conducted to examine its application with waterflooding. Additionally, ultrasonic waves are used in engineering to determine the stability of sediments through dispersion and disaggregation. This study aims to incorporate both the ultrasonic waterflooding aspect with the stability of the sediment by investigating the impact of sonication exposure duration on particle size and oil recovery under waterflooding. Six (6) coarse sand samples were used in the experiment to simulate the porous media found in a sand pack. A sieving test was conducted on each sand sample to obtain its Particle Size Distribution (PSD) curve prior and post sonication. Waterflooding was conducted using 3% NaCl brine as the wetting phase and decane (C10H22) as a non-wetting phase. Ultrasonic waves were applied continuously throughout the waterflooding durations (i.e., 15,30,45 minutes), and both temperature and decane recovery were recorded. The results show that ultrasonic results in minimal additional recovery less than 2%, and an increase in temperature of 2-8°C was observed. However, longer sonication results in higher particle disaggregation, which reduces permeability by15.50%-41.85% and can result in sand production. This study can be continued through investigation on the utilization of cyclic ultrasonic-assisted waterflooding as a technique that may aid in recovery without causing detrital effects to the reservoir sand layer.Keywords: permeability, stability, sonication, dispersion, size distribution

Method for predicting drying-wetting and scanning soil-water characteristic curves

A method for predicting drying-wetting and scanning soil-water characteristic curves (SWCCs) of a soil has been proposed, which mainly uses Fredlund and Xing’s SWCC function with the fitting parameters evaluated from the saturated permeability (ks), grain size distribution curve and plastic index (PI) of a soil. The usefulness of the method has been checked by applying it to three sets of test data from this study and seven sets of test data from the literature. Fair and acceptable predictions were obtained. It is suggested that the method can be used to approximately predict SWCCs of a soil in case there is no test data available.

The impacts of freeze\u2013thaw cycles on saturated hydraulic conductivity and microstructure of saline\u2013alkali soils

Study on the microscopic structure of saline–alkali soil can reveal the change of its permeability more deeply. In this paper, the relationship between permeability and microstructure of saline–alkali soil with different dry densities and water content in the floodplain of southwestern Shandong Province was studied through freeze–thaw cycles. A comprehensive analysis of soil samples was conducted using particle-size distribution, X-ray diffraction, freeze–thaw cycles test, saturated hydraulic conductivity test and mercury intrusion porosimetry. The poor microstructure of soil is the main factor that leads to the category of micro-permeable soil. The porosity of the local soil was only 6.19–11.51%, and ultra-micropores (< 0.05 μm) and micropores (0.05–2 μm) dominated the pore size distribution. Soil saturated water conductivity was closely related to its microscopic pore size distribution. As the F–T cycles progressed, soil permeability became stronger, with the reason the pore size distribution curve began to shift to the small pores (2–10 μm) and mesopores (10–20 μm), and this effect was the most severe when the freeze–thaw cycle was 15 times. High water content could promote the effects of freeze–thaw cycles on soil permeability and pore size distribution, while the increase of dry density could inhibit these effects. The results of this study provide a theoretical basis for the remediation of saline–alkali soil in the flooded area of Southwest Shandong.

Grindability Evaluation of Fragmented Clay Bricks for Performance Analysis of Cement Paste Incorporating Clay Brick Powder

.Milling treatments for evaluating grindability of pozzolanic materials using ball mill have been employed with limited research focused on fragmented clay bricks. Of great importance of the milling treatments are the milling times and sample masses. Moreover, the applications of grindability of Clay Brick Powder (CBP) in cement paste are found to be limited. In this paper, the effects of increasing milling time and increasing sample mass of fragmented clay bricks on fineness of resulting CBP were examined using ball milling and particle size distribution curves. The Scanning Electron Microscope (SEM) was implemented to characterise the morphological properties of CBP. Compliance of CBP with minimum requirements for pozzolanic characteristics was verified using X-Ray Fluorescence and X-Ray Diffraction. Extensive Image analysis using ImageJ and Origin was employed to verify significant variations of particle size, particle distribution, porosity and surface roughness for different sample mass. Properties of cement paste containing CBP were assessed to capture essential elements on the influence of CBP fineness on density and prismatic compressive strength of cement paste. The overall influence of grinding illustrated that a decline in particle size of CBP was facilitated in samples subjected to prolonged milling times. On the other hand, the reduction of sample mass fed in ball mill corresponded to enhancement of fineness of CBP. Meanwhile, qualitative evaluation of three-dimensional reconstruction of SEM images using ImageJ proved that significant enhancement of fineness led to reduction of surface roughness. Quantification of surface porosity demonstrated that reduced surface porosity originated from finer CBP. Consequently, the research established the feasibility of incorporating finer CBP in cement paste, which significantly contributes to enhancement of prismatic compressive strength. Concerning cement paste density, the inclusion of CBP in cement was not of significant consequence on its density due to similar packing densities of CBP.

An integrated pore size distribution measurement method of small angle neutron scattering and mercury intrusion capillary pressure

Small-angle neutron scattering and high-pressure mercury intrusion capillary pressure testing are integrated to analyze the pore size distribution of the broad sense shale oil reservoir samples of the Permian Lucaogou Formation in the Jimsar Sag, Junggar Basin, China. The results show that, compared with the measurement method integrating gas adsorption and mercury intrusion, combination of small-angle neutron scattering and mercury intrusion can more accurately characterize full-scale pore size distribution. The full-scale pore size distribution curve of the rock samples in the study area includes two types: the declining type and submicron pore-dominated type. The declining type is mainly found with silty mudstone and dolomitic mudstone, and most of its pores are smaller than 80 nm. Silt-fine sandstones and dolarenite are mostly of the submicron pores-dominated type, with most pores smaller than 500 nm. They also present large specific pore volumes and average pore diameters of macropores and are the favorable lithogenous facies for development of high-quality reservoirs.

Digital concrete modelling: An alternative approach to microstructural pore analysis of cement hydrates

The porous structure of hydrated cement has a significant effect on its governing properties, such as strength, density, ion-diffusion, acoustic performance etc. However, direct observation of the 3D pore structure is limited by high stochasticity and multiscale features. We constructed a statistically equivalent 3D micropore structure using a digital concrete model that used a probabilistic map derived from 2D cross-sections and parameter sets calibrated via a deep learning neural network.Based on the replica of cement pore structure, image analyses and virtual mercury intrusion porosimetry (MIP) tests were compared with experimental outcomes. In particular, the pore size distribution curves matched well for both MIP and image analysis approaches. However, although the fractal dimension derived from each 2D image linearly correlated with the corresponding porosity, it tended to underestimate the complexity of the pore structure. Correspondingly, the 3D fractal dimension showed a periodic pattern to voxel size in log-scale and was slightly higher than the MIP results. The tortuosity factor also had a linear correlation to voxel size, resulting in an overestimation of the pore structure’s tortuosity. We demonstrated that the digital concrete model could serve as an alternative approach to studying the microstructural pore analysis of cementitious material through such a comparison. This study’s outcome helps to understand the structure–property link in cement with the potential to transform traditional analytical processes of cementitious materials.

Enormous Promotion of Photocatalytic Activity through the Use of Near-Single Layer Covalent Organic Frameworks

Enormous Promotion of Photocatalytic Activity through the Use of Near-Single Layer Covalent Organic Frameworks

Characteristics and evolution of pore types in marine carbonate mudrocks, selective early to late Jurassic succession, central Saudi Arabia

This study's main goal was to recognize pore types, sizes, and abundance within three carbonate mudrocks units (parts of Upper Marrat, Tuwaiq Mountain Limestone, and Hanifa formations) located in Central Saudi Arabia. The methods used for this study were petrographic thin section analysis, helium porosity measurements, and X-ray diffraction. Backscattered scanning electron microscopy with energy dispersive scanning, micro-computed tomographic scanning, Total Organic Carbon “TOC” analysis, nuclear magnetic resonance, N2 adsorption analyses were used for qualitative and quantitative pore type characterization. Three carbonate mudrocks lithofacies were specified in Hanifa Formation Hawtah Member: LFH1, LFH2, and LFH3. Two lithofacies were defined in the Tuwaiq Mountain Limestone mudstone: LFT1 and LFT2. Two mudstone lithofacies were identified in the Upper Marrat Formation: LFM1 and LFM2. Intra-skeletal, intraparticle, and secondary OM-hosted pores are found in the Hanifa mudstone lithofacies. Intra-skeletal, small scale interparticle (pyrite framboids), and OM-hosted pores were predominant in Tuwaiq Mountain Limestone mudstone lithofacies. Small scale interparticle pores (euhedral calcite) and secondary OM-hosted pores were found in both mudstone lithofacies of the Upper Marrat Formation. All pore types were linked to corresponding diagenetic processes and burial events. NMR-relaxation time curves and pore size distribution curves revealed that LFH1 and LFH3 lithofacies has higher pore abundance than in the LFH2 lithofacies. LFT1 and LFT2 lithofacies have similar bimodal relaxation time distribution with slightly higher abundance observed in the LFT1 lithofacies. LFM1 and LFM2 lithofacies have similar bimodal relaxation time distribution with slightly higher abundance observed in the LFM1 lithofacies. These results can be used as input parameters to generate fluid flow simulation to determine these carbonate-rich mudrock reservoirs' potentiality.

Determination of Geotechnical Properties and Stability of Expansive Soil using Fly Ash

This study was conducted to have a detailed analysis of the geotechnical properties of expansive soil and fly ash from Sipat thermal power plant. It reported the findings of laboratory studies on certain common physical and geotechnical properties. The chemical properties and morphology of the black cotton soil (BCS) and fly ash is also determined using scanning electron microscopy and X-ray diffraction test. The geotechnical test includes determining specific gravity, particle size distribution, moisture content, standard proctor test, free swell index, and Atterberg’s limit. The different compositions of expansive soil with fly ash, yellow soil, moorum, and sand are studied. BCS was evaluated with fly ash, fly ash and sand, BCS with yellow soil, and moorum and fly ash. The study also analyzed the details and results of different tests conducted on soil samples. The results showed that strength and fly ash are inversely proportional; as fly ash increases, strength decreases, and vice versa. Fly ash was added from 20 to 80 % by replacing expansive soil by weight. The results indicated that expansive soil can be stabilized by the addition of fly ash to a limit of 10 to 20 %.&#x0D; HIGHLIGHTS&#x0D; &#x0D; The XRD And SEM results shows the mineral present in the FlyAsh and Expansive soil&#x0D; The geotechnical properties of Flyash and expansive soil is determined&#x0D; The OMC increases with decrease in densities&#x0D; The Particle size distribution curve shows the soil is GW soil&#x0D; &#x0D; GRAPHICAL ABSTRACT

Particle size distribution and crystallinity as indicators of kaolinite genesis

The possibility of using the particle size distribution curve obtained by the laser diffraction method to determine the kaolinite genesis is considered in the paper. The full width at half maximum (FWHM) and the peak shape index (PSI) are proposed to characterize the distribution curve shape. The normal distribution of microcrystals with a perfect structure and clear faceting is associated with a single mechanism of the rock transformation into kaolinite. Most likely, such a mechanism is the solid-phase transformation of the parent rock minerals into kaolinite. The lognormal distribution, reflected by the deformation of the descending branch of the distribution curve peak, is associated with two mechanisms of kaolinite formation. In addition to solid-phase transformations, kaolinite crystallization from the degradation products of the parent rock occurs. Secondary kaolinites are characterized by a broad particle size distribution, a wide FWHM, and low crystal perfection in comparison with primary kaolinites. It is associated with a change in the kaolinite properties as a result of their transportation from the primary weathering crust to the sedimentation zone. It is proposed to use the data on the particle size distribution together with X-ray diffractometry (XRD) and scanning electron microscopy (SEM) for the first time to determine the kaolinite genesis.

Effects of Biochar and Compost on Soil Physical Quality Indices

ABSTRACT Biochar and compost are important organic amendment materials for modifying the distribution of pore size in soils. The main idea of this study was to investigate the impact of date palm biochar, compost and their combination on soil water parameters, pore size distribution curves and soil aggregates stability at the rates of 1%, 2%, 3% and 4% (10, 20, 30 and 40 g kg-1). In this study, shape (standard deviation (SD), kurtosis and skewness) and location (dmode, dmedian and dmean) parameters, water stable aggregates (WSAs), mean weight diameter (MWD), geometric mean diameter (GMD) and erodibility factor (Kerodibility) were measured and evaluated. Results showed that the indicators of pore size distribution functions for untreated soil (control) were 31.6, 25.8, 23.5, 3.3, −0.16 and 1.14 for dmode, dmedian, dmean, SD, skewness and kurtosis, respectively. While, WSA>0.25 (macro aggregates), MWD, GMD and Kerodibility were 15.94, 0.19, 0.39 and 0.0895, respectively. Here, dmode, dmedian, dmean, SD, skewness and kurtosis were changed due to application rates of biochar, compost and the mixture of biochar–compost, significantly. The application rate of 4% of the biochar–compost mixture had the highest effects, and dmode, dmedian, dmean, SD, skewness and kurtosis were 18.9, 13.3, 11.3, 4.9, −0.21 and 1.15, respectively. Mixing biochar, compost and biochar–compost mixture reduced equivalent pore diameters, dmode, dmedian, dmean, and increased the indicators of WSA>0.25, MWD, GMD and kerodibility. The factors of WSA, MWD, GMD and kerodibility were enhanced. Thus, the application of biochar, compost and biochar–compost mixture could improve water retention and water use efficiency (WUE) of sandy soils.

Internal erosion: critical hydraulic gradient in one-dimensional vertical seepage and its relation to soil gradation

A hydromechanical envelope that governs the onset of soil erosion by seepage-induced internal instability is examined with reference to theoretical and laboratory stress-gradient paths for one-dimensional upward and downward seepage flow. The method is validated from permeameter test results on glass ballotini. Using the theory, analysis of a database of 22 gradations establishes a semi-empirical relation between attributes of a grain size distribution curve and a stress-reduction factor governing potential for internal erosion. The semi-empirical relation provides a screening tool for susceptibility of a soil to seepage-induced internal instability.

Effect of Microwave Pretreatment on Grindability of Lead-Zinc Ore

The influence of microwave pretreatment on grindability of lead-zinc ore was studied through comparison analysis on the changes of particle size distribution, percentage of below 0.074 mm, energy consumption, and other indexes of grinding products before and after microwave pretreatment in the ball milling process. The results showed that the grindability of lead-zinc ore was improved obviously by microwave pretreatment. The particle size distribution curve of the grinding products was obviously higher than that of the samples without microwave irradiation. The yield of size fraction below 0.074 mm was also improved in a certain degree. Pulsed microwave irradiation was more effective than continuous microwave irradiation when other microwave parameters were consistent. The comprehensive energy consumption of lead-zinc ore pretreated by different microwave parameters was lower than that without microwave irradiation under the same grinding fineness. The total energy consumption was down by 30.1% when irradiated for 15 s at 7 kW power, and it was lower than that without microwave irradiated. The results showed that pulsed microwave pretreatment was more effective in reducing the comprehensive energy consumption of grinding process for lead-zinc ore. And water quenching after microwave irradiation can improve the grindability and reduce the energy consumption of grinding for lead-zinc ore.

Precise and fast microdroplet size distribution measurement using deep learning

Microfluidic technology is a versatile approach to improve the production of various fine chemicals and materials, where precise and fast size measurement of microdroplets in microscopic images is of pivotal significance for microfluidic device design. With recent developments in convolutional neural networks, we herein proposed a state-of-the-art deep learning-based method to cope with microdroplet size measurement and largely ease manual workload. The proposed method instance-wisely segments microdroplets with deep learning, and then fits their boundaries to obtain precise size distribution curves. Even overlapped droplets and small-sized satellite droplets can be detected and measured, which is not achievable in previous computer methods. Incredibly, diameter measurement error is as small as 0.75 μm, and the measurement efficiency is increased ~1000 times compared to manual measuring. This work not only sheds light on intellectual size measurement of microdroplets, but also points out a new way to promote microfluidic technology through deep learning methods.