Particle Gradation Research Articles

Particle grading effect on properties of reactive MgO‐bonded castables

AbstractRefractory matrix is a key factor in determining the properties and performance and thus the lifetime of refractory materials. The particle gradation affected both the matrix composition and microstructure. In this study, six particle gradations of high‐alumina castables were prepared based on Andreasen's model (q = 0.22, 0.24, 0.26, 0.28, 0.30, and 0.32). The influence of particle gradation on properties of high‐alumina castables bonded with 4.0 wt% reactive MgO (RM) was investigated with respect to the difference in matrix composition and microstructure. The results show that castables with q values of 0.24 and 0.26 exhibited better physical and mechanical properties after curing and drying. The castables with a q value of 0.22 showed the best volume stability after firing at 1600°C, whereas, castables with a q value of 0.24 exhibited the highest mechanical strength, and residual CMOR ratio after thermal shock testing. Based on the property analyses of castables, the optimal q value of RM‐bonded castables would be around 0.24.

A Novel Amphoteric Ion-Modified, Styrene-Based Nano-Microsphere and Its Application in Drilling Fluid.

With the gradual depletion of shallow oil and gas, deep oil and gas has become the focus of development. However, deep formations generally face the challenge of high-temperature and high-salinity, and drilling fluid agents are prone to failure, leading to drilling fluid intrusion into the formation that can cause serious drilling accidents such as well bore collapse. For this, a styrene-based nano-microsphere (SSD) modified with amphoteric ions was developed, with a particle size of 228 nm which could resist temperatures up to 200 °C and sodium chloride (NaCl) up to saturation. SSD has significant salt-responsive properties and its aqueous dispersion becomes transparent with increasing salinity. The SSD provided superior plugging performance in solutions containing NaCl, with a core plugging efficiency of 95.2%, and it was significantly better than the anion-modified microspheres. In addition, in drilling fluids under high temperature and high-salinity conditions, the SSD promotes particle gradation of drilling fluids and improves the zeta potential through its own plugging and synergistic effect with clay, which significantly improves the comprehensive performance of drilling fluids, such as stability, rheological performance, and filtration reduction performance. The development of SSD provides a new idea for research of high-temperature and high-salinity-resistant drilling fluid agents.

Applications of Recycled and Crushed Glass (RCG) as a Substitute for Natural Materials in Various Fields-A Review.

Glass is a substance that is present in most houses since glass-based items are made and consumed in relatively high quantities. This has led to the buildup of glass in concerning quantities all over the world, which is a problem for the environment. It is well known that glass has several advantageous physiochemical features that qualify it as an appropriate material for use in the construction industry as an aggregate. The features include being non-biodegradable, resistant to chemical assault, having low water absorption, having high hydraulic conductivity, having temperature-dependent ductility, having alterable particle gradation, and having a wide availability in a variety of forms and chemical compositions. Because of these qualities, glass has been used in various investigations and field tests conducted in civil engineering to evaluate its effectiveness as an engineering aggregate and to develop environmentally friendly management strategies for waste glass. These studies and research have utilized glass in various forms, such as fine recycled glass, medium recycled glass, coarse recycled glass, powdered glass, and glass-based geopolymers. This study focuses on research studies that present results on physicochemical, mechanical, and durability characteristics. These studies and research contain samples of pure glass or glass as replacement percentages in materials (0-100%), including but not limited to unbound granular materials (such as recycled concrete aggregates and crushed rock). In light of the information assembled in this review article, it is legitimate to claim that glass has strong promise as a material in various civil applications.

Study on Correlations between Tailings Particle Size Distribution and Rheological Properties of Filling Slurries

The influence of the mass concentration and particle size distribution on rheological parameters and slump was investigated by analyzing the mixture of overflow tailings (OT) and classified tailings (CT). The correlation between the rheological parameters, slump and characteristic value of the tailings particle diameter was discussed. Finally, the ratio parameters of a mixed tailings filling slurry were optimized using a lead–zinc mine in Guangdong, China as the engineering background. The results showed a quadratic decrease in the slump of the tailings slurry as the mass concentration increased, while the slump decreased with a decreasing particle size. With the increase in the mass concentration, the yield stress of the tailings slurry follows a quadratic function, while the plastic viscosity exhibits linear growth. The influence of tailings fine particles on the sensitivity of the yield stress and plastic viscosity to the mass concentration is reduced as their content increases. The yield stress and plastic viscosity of the tailings slurry exhibit a quadratic function decrease and linear growth as the slump increases. The slump of the tailings slurry is related to the particle size characteristic value and the mass concentration of the slurry. The correlation coefficient between the yield stress and the aggregate characteristic particle size increases most obviously at d10~d50, and the increase in the characteristic particle size will enhance the correlation between the yield stress and particle gradation. The correlation coefficient between the plastic viscosity and aggregate particle gradation parameters exhibits an initial increase followed by stabilization with an increasing characteristic particle size, with the most significant increase observed at d10~d50.

Numerical Simulation of Ground Subsidence Factors Resulting from Unpressurized Pipeline Rupture Below the Water Table

The rupture of an unpressurized pipeline below the water table can lead to the leakage of groundwater along with soil particles into the pipeline. This not only causes blockages in the pipeline but, more critically, can result in ground subsidence. Understanding the factors influencing this phenomenon is a subject of great interest. To delve into this matter, this study employs the DEM-CFD methodology to synergistically encompass particle dynamics and interactions within the flow domain. It introduces an innovative framework for simulating water and soil erosion subsequent to the rupture of subaqueous unpressurized pipelines. This pioneering approach introduces a novel modeling and simulation paradigm catering to the analysis of intricate phenomena of this nature. Upon validating the flow field, our investigation specifically focused on three key factors: particle friction coefficient, groundwater level, and particle size distribution. We conducted a thorough examination of the process and mechanism of water and soil loss at the pipeline leakage point and the subsequent development of stratum subsidence. Our results indicate that particles with a friction coefficient of 0.6 had a reduced maximum displacement by 8.9%, compared to particles with a friction coefficient of 0.3. Similarly, a groundwater depth of 2 m resulted in a 29.6% decrease in maximum displacement compared to a 4 m depth, with a corresponding 160.9% increase in maximum force chain strength. Discontinuous particle gradation, in contrast to continuous gradation, yielded a notable 40.3% reduction in maximum displacement and a substantial 495.1% increase in maximum force chain strength. This underscores the noteworthy influence of particle friction coefficient, groundwater table elevation, and soil particle diameter on the stability of the overlying soil strata in the vicinity of a compromised unpressurized conduit.

A novel method for dry density forecasting of high-speed railway graded aggregate fillers based on the PSO-ANN model

To address the lack of intelligent prediction research on dry density, this paper proposes a machine learning-based prediction method for compaction quality of high-speed railway graded aggregate (HRGA) fillers. Firstly, to reveal the main control characteristics between HRGA fillers performance and dry density, 80 sets of vibration compaction tests were carried out. The Grey Relation Analysis (GRA) algorithm was used to quantify the degree of influence between the properties of particle gradation, particle shape and particle fragmentation, and dry density. Then, a stable database of dry density of HRGA fillers was established through 300 lab vibratory compaction tests. Finally, three Hybrid Machine Learning (ML) models (PSO-ANN, PSO-SVR, and PSO-RF) was used to fit the nonlinear relationship between the mian control characteristics and dry density. The results show that the gradation parameter b, maximum particle size dmax, and gradation parameter m are strongly correlated features, with a mean value of correlation reaching 0.77. These three features are considered the main control factors affecting the dry density and are used as input features for the subsequent ML prediction model. Moreover, the PSO-ANN model is shown to have the higher prediction accuracy with R2 = 0.9634 in the test set and lower uncertainty with U95= 0.1413, Tstat= 0.533, and SI = 0.2306 in the test set for dry density predictions. The finding can provide a significant reference for intelligent compaction.

Filling parameters and process optimization of mining–filling synergistic coal-based solid waste paste in Renjiazhuang mine

In this paper, the authors address the issue of large solid waste output and surface subsidence in the western coal base. They focus on the 110904 filling working face of Renjiazhuang Mine and employ a combination of theoretical analysis, numerical simulation, and field practice to analyze the limit caving step and cycle pressure step of the working face. The authors propose a mining-filling coordination scheme called “three mining and one charging”. Through numerical simulation, they demonstrate that this scheme ensures the time-space continuity of the mining-filling cycle and is theoretically feasible. Additionally, the authors conduct nine groups of orthogonal simulation tests to identify the main factors affecting the filling effect. They conclude that the filling rate is the primary controlling factor, and there is a positive correlation between the filling rate and 1-day strength. The authors implement hanging pipe filling in the return air roadway of the 110904 working face, achieving a filling material 1-day strength of 2 MPa and a filling ratio of 80%. The mining-filling synergy scheme proves effective and feasible. However, the issue of pipe plugging during the filling process requires further optimization of the particle gradation in the subsequent filling material ratio scheme. Overall, the proposed mining-filling collaborative process serves as a theoretical reference for similar filling faces.

Influence of particle gradation and morphology on the deformation and crushing properties of coarse-grained soils under impact loading

Influence of particle gradation and morphology on the deformation and crushing properties of coarse-grained soils under impact loading

Investigation on Bearing Characteristics of Gravity Wharf Rubble-Mound Foundation in Different Influencing Factors

The use of the heavy hammer compaction method can enhance the bearing characteristics of underwater rubble-mound foundations. This is crucial to ensure the safety and stability of port and coastal engineering projects. In the present work, a combination of image-recognition technology, 3D laser scanning technology, a discrete element numerical simulation, and a field test was first utilized to establish riprap particles and reconstruct a discrete element numerical model of a rubble-mound foundation, and then the effects of various influencing factors on the bearing characteristics of the rubble-mound foundation were studied. The main conclusions are as follows. (1) The load–settlement curve of the rubble-mound foundation can be divided into three stages: rapid growth stage, slow growth stage, and failure stage. (2) The ultimate bearing capacity of the rubble-mound foundation is positively correlated with the vibration time and vibration amplitude. The riprap particle size and the foundation thickness have negligible effects on the ultimate bearing capacity of the rubble-mound foundation. (3) When adjusting the vibration time, vibration amplitude, and foundation thickness, the settlement value of the rubble-mound foundation tends to increase as the compactness increases. On the other hand, the effects of factors such as the riprap particle size, riprap particle gradation, and vibration frequency on the compactness and settlement value of the rubble-mound foundation are less significant.

Controllable preparation of aerogel/expanded perlite composite and its application in thermal insulation mortar

The extremely low strength and high cost of aerogel limit its applicability in energy-efficient buildings. In this paper, the controllable preparation method of aerogel/expanded perlite (AEP) was developed, and the particle gradation effect on AEP thermal insulation mortar (AEPM) was assessed, which provided an effective way for the application of aerogel and AEP in buildings. The results showed that the acid/base catalysis two-step method was imperative for preparing AEP. It was also found that the pH of SiO2 hydrosol should be controlled within 3.2–3.5, and the corresponding gel time of SiO2 hydrosol was 30–90 min. The impregnation-adsorption process of EP adsorbing SiO2 hydrosol should be completed before the initial viscosity of 3 mPa·s changes. The amount of SiO2 hydrosol adsorbed by EP had a logarithmic relationship with the adsorption time under the adsorption of ambient pressure (AP), whereas its linear relationship with the adsorption pressure under the adsorption of vacuum pressure (VP) was found. The pores of expanded perlite (EP) were filled with well-structured aerogel due to the controlled preparation of AEP. Thus, the AEP bulk density increased by 24%-50% compared with EP. However, the thermal conductivity decreased by 14.6%-31.8%, and the particle strength of AEP was not significantly improved compared with that of EP. AEPM prepared by AEP showed typical characteristics of high strength and low thermal conductivity. The compressive strength of AEPM was 6.5% lower than that of EPM but more than twice that of AERM, while the corresponding water absorption and thermal conductivity were 27.6% and 26.6% lower than EPM. As a new nano-micron porous composite, AEP has great applicability in developing thermal insulation materials, phase change materials, and adsorption materials.

Effects of incorporating large quantities of nickel slag with various particle sizes on the strength and pore structure of cement-based materials

Firstly, nickel slag sand with a concentrated particle size distribution in the range of 2.36–0.60 mm was used to replace the mechanism sand in the ratio of 0%, 25%, 30%, 50%, 70% and 100%. Second, partial particle size substitution was used to partially replace nickel slag sand with particle sizes of 2.36–1.18 mm and 1.18–0.60 mm in proportions of 0%, 30%, 50%, 60%, 70% and 100%, respectively, to optimize particle gradation of mixed sand. Cement mortar specimens were prepared using different mixed sands composed of the above two substitution methods and at a water-cement ratio of 0.5. Then, the effects of nickel slag sand with varying substitution methods on the strength and pore structure of cement-based materials were investigated by mechanical tests, mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). Standard sand was also used as an experimental control group. The experimental results revealed that the maximum flexural and compressive strength of nickel slag sand using a full-size substitution group corresponded to an optimal dosage of 30%, while the optimal dosage of nickel-slag sand using a specific-size substitution group was 60%. The water absorption of the two particle sizes replaced the specimens decreased and then increased with the inclusion of nickel slag sand. The results showed a consistent trend with the variations in electrical resistivity and total porosity of MIP. From the SEM photographic results of the SS, MS, NF30 and NP60 specimens, the cement paste can be more tightly wrapped around the round spherical nickel slag particles. NF30 and NP60 specimens showed a denser internal structure, multi-dimensional hydration products and a lack of pores and microcracks, which is fully consistent with experimental results of mechanical properties and microstructures.

The role of ultra-fine supplementary cementitious materials in the durability and microstructure of airport pavement concrete

Conventional Supplementary cementitious materials (SCMs) are indispensable constituents of high-performance concrete, despite their potential drawback of reducing the early strength of concrete. Ultra-fine supplementary cementitious materials (USCMs) have been employed to expedite the pozzolanic reaction and refine micro-scale particle gradation in airport pavement concrete. The investigation encompassed an assessment of mechanical properties, durability, phase assemblage, pore structure, morphology, and microstructure. Results showed that the incorporation of USCMs significantly enhanced the flexural and compressive strength of concrete during the early age, exhibiting respective improvements of 25.4% and 12.8%, respectively. Moreover, the freezing-thawing resistance was enhanced by a factor of 1.6, and the chloride penetration resistance was improved approximately 4 times. These enhancements can be attributed to the heightened pozzolanic and filling effects of USCMs, which resulted in the consumption of more calcium hydroxide (CH) at 7 d and facilitated the growth of additional calcium silicate hydrate (C-S-H) gel, along with lowering hydration heat and decreasing remarkably porosity. Notably, the incorporation of USCMs led to a considerable improvement in the volume fraction of harmless pores (with pore diameter ≤ 50 nm), optimizing the pore structure of the concrete and thereby augmenting its mechanical properties and durability.

Influence of Particle Gradation and Penetration Velocity on Deformation Behavior of Sandy Soil Based on CPT

Influence of Particle Gradation and Penetration Velocity on Deformation Behavior of Sandy Soil Based on CPT

Study on macro and micro shear strength of continuously graded and gap-graded sand

The particle gradation of sand has a significant influence on its shear strength, yet the similarities and differences between the effects of continuous and gap grading have yet to be fully explored. In this study, the discrete element method (DEM) was used to simulate biaxial tests on granular samples that were both continuously graded and gap-graded. The macroscopic analysis revealed that the shear strength of continuously graded sands increases initially and then decreases as the uniformity of particle size distribution decreases. On the other hand, the lack of medium particles in gap-graded sands amplifies the difference in particle size between coarse and fine particles, leading to a decrease in shear strength. Microscopically, both continuous and gap gradings affect the internal packing structure of the particle assembly, which consequently affects particle stress distributions, contact forces, coordination numbers, stress-induced anisotropies, and contact force networks, thus having an impact on the macroscopic shear strength. The global uniformity of particle size distribution was unidirectionally affected by continuous grading, while gap grading had a locally bidirectional influence. These findings provide a better understanding of the effects of particle grading on the macroscopic shear strength of sands.

Laboratory evaluation of the filtration behavior of three filters wrapped around drain pipes in fine tailings based on a radial flow test

Installing drain pipes is an effective way to control the height of the saturation line to improve the stability of tailings dams in mine projects. The filtration and clogging behaviors of filters wrapped around drain pipes have a great impact on their drainage capacity. This article presents results from radial filtration tests with drain pipes wrapped by filtration materials in fine-grained tailings. In the tests, three fibrous filters with different production technologies were used under different hydraulic conditions. The test results were interpreted based on the drainage characteristics of the system, the clogging characteristics and mechanism of each filter after testing, and the particle gradation passing through each filter. The results showed that the needle-punched nonwoven geotextiles had good soil retention properties and poor drainage properties, and one denser cake layer was formed upstream as the experiment progressed. For the heat-bonded nonwoven geotextiles with larger apertures and thinner thicknesses, there was a slight degree of clogging and acceptable drainage capacity. Steel wire mesh with a thinner thickness and homogeneous mesh structure seemed to offer the best anti-clogging and drainage performance by retaining coarse particles and washing out fine particles. Thus, it is inferred that drain pipes wrapped with steel wire mesh are a good choice for alleviating the physical clogging problem.

Numerical simulation on transport behavior of gradated coarse particles in deep-sea vertical pipe transportation

Flow pattern and hydrodynamic characteristics of coarse particles in deep-sea hydraulic lifting pipes are simulated using a numerical approach developed by combining the computational fluid dynamics method with a discrete element method in the Euler–Lagrange framework. This paper examines the effects of feed concentration, two-phase flow initial mixture velocity, and particle gradation on the dynamic characteristics of particles and flow pattern in the pipe by validating the rationality of numerical simulation. The results demonstrate that particles are distributed from the pipe center to the pipe wall, while the lift force causes more particles to be distributed in the pipe center. Moreover, greater inertia makes large particles more concentrated in the center. Particle-induced turbulence modifies the lift force and causes particles to move from the pipe center to its wall. Due to the increasing trend of lift force, particles gather toward the center of the pipe at an increasing pace as the initial velocity increases. The greater the feed concentration, the more particles disperse toward the pipe wall due to the violent momentum exchange caused by the high concentration and the significantly altered lift force caused by the high turbulent kinetic energy resulting from a high concentration. From the particle gradation 1:1:1 to 1:6:1, the pressure drop decreases gradually as the reduction in small particles decreases the number of particles near the wall, and the frictional energy loss between the particles and the pipe wall decreases.

Developing an advanced ANN-based approach to estimate compaction characteristics of highway subgrade

The current methodology of assessing the compaction characteristic of subgrade fillers is time-consuming. The spot-sampling method and the following laboratory tests bring bias to engineering practice. This study proposes an advanced approach to determine the maximum dry density, optimum moisture content, and compactness of subgrade based on ANN algorithms. A large number of compaction tests are performed to assess the compaction quality of various types of subgrade fillers. The particle gradation is specifically considered. Wave propagations of the compacted specimen are assessed based on the ultrasonic test, and the anisotropic feature is demonstrated. The dynamic elastic parameters are derived to further reveal the interaction mechanism. A dataset is proposed by combining these laboratory data and the literature data. The PSO-BP-NN model is developed to automatically predict the compaction parameters of different filling materials. A positive correlation is demonstrated between the elastic modulus and the total density, and Poisson’s ratio illustrates an inverse trend. The compaction energy is influential to the maximum dry density while the moisture content has the greatest impact on the compactness. This study aims to develop an accurate model to replace the extensive Proctor test and efficiently evaluate the compaction quality of subgrade for highway constructions.

Enhancement of shear strength of cohesionless granular soil using M-Sand dust waste

In recent times, shortage in the availability of river sand for construction activity has led to the production of Manufactured Sand (M-Sand) in huge quantities. This in turn has led to the production of huge volumes of M-Sand Dust Waste (MSDW) as a waste by-product which is disposed of nearby, in available open spaces and landfills. This leads to wastage of valuable land areas and also pollutes the air in surrounding areas leading to health hazards to the humans. An effort has been made in this project, to check the suitability of utilizing MSDW as a filling material in reinforced earth walls and to replace the conventional granular backfill materials with MSDW. As per IRC: SP: 102-2014, based on the particle gradation of MSDW, liquid limit, plastic limit test and direct shear test, it was observed that MSDW is suitable to be utilized as filling material in reinforced earth walls. Also, index properties of 3 types of granular backfill materials namely Silty Sand, M-Sand and River Sand were studied in this project and MSDW was used as a replacement to these granular soil in percentages of 20%, 40%, 60% and 80% by dry weight of soil. Based on the experimental results, it was concluded that ideal percentage replacement of Silty Sand and M-Sand with MSDW was found to be 20% for which maximum angle of internal friction (ϕ) was observed to be 43° and 49° respectively. Optimum percentage replacement of River Sand with MSDW was found to be 80% for which maximum ϕ value was observed to be 45° in comparison to 40° observed for River Sand without replacement.

Study on shear characteristics of calcareous sand with different particle size distribution

For the island and reef project formed by filling calcareous sand, the problems of wide particle size distribution (PSD) and complex mechanical properties have to be faced. Therefore, in order to provide basic mechanical parameters for the construction of the island and reef project, triaxial shear tests were carried out on calcareous sands with five different typical PSDs. The results showed that as particle gradation became narrower, the axial strain corresponding to the strain-softening point all showed a decreasing trend and their differences gradually decreased; the confining pressure has a significant impact on the volumetric deformation modulus of calcareous sand with a wide PSD. The cohesion of calcareous sand showed a positive correlation with non-uniformity and curvature coefficients, while the variation of an internal friction angle showed a parabolic law; the internal friction angle also changes in the parabola with the change of fine particle contents. Furthermore, by establishing the PFC3D discrete element model, it was found that the numerical simulation results were in good agreement with the test results, which verifies the feasibility of the numerical simulation and the rationality of the mesoscopic parameter calibration. It was discovered that the wider the particle gradation range, the greater the axial strain corresponding to the critical coordination number; the sample with a narrow gradation interval was more likely to present a rotating displacement field to form a penetrating shear band. This study can provide design parameters for stability analysis of high and steep slopes in calcareous sand sites.

Experimental study on burning characteristic of liquid fuel immersed in porous media bed: Effect of particle gradation

A series of burning test was conducted to investigate the effect mechanism of particle gradation on burning characteristic of liquid fuel immersed in porous media. High-purity quartz equipped with two-component discontinuous gradation and ethanol liquid were employed as porous bed and liquid fuel. The characteristic parameters, e.g., burning rate, temperature distribution, flame feature and burning duration, etc., were recorded and identified. Results show that the burning characteristic of liquid fuel immersed in porous media with gradation configuration is conjunctively influenced by capillary effect and thermal conductivity of porous media. For the porous media bed with fine particles, capillary effect plays a dominant role in the variation trend of burning rate. While for the porous media bed with good gradation, under the effect of better contact condition and more coordination numbers, thermal conduction enhanced by particle gradation dominates the burning characteristic. Meanwhile, the burning rate of porous bed immersed by liquid fuel demonstrates stage-variation feature: a rapid growth stage dominated by direct flame thermal feedback and an attenuation-stable stage dominated by thermal conduction. Due to the “back effect”, the burning rate has a quasi-stable phase in middle-and-late stage, which is positively correlated with the one-half power of media porosity. Moreover, due to the enhancement of thermal conductivity, the downward heat transfer rate of porous media with good gradation is relatively faster. In addition, there is still a positive tendency between flame height and burning rate. This work is expected to provide some references for understanding the burning characteristics of liquid fuel immersed in porous media and burning-decontamination operation.