Particle Rearrangement Research Articles

Causes of the high friction angle of diatomaceous soil: microscale and nanoscale insights

Diatomaceous soil has geotechnical properties that differ fundamentally from those of common non-diatomaceous soils due to the presence of diatom microfossils with biological origins. Despite its dominant fines content, diatomaceous soil usually has high frictional shear resistance (approaching that of sand). Currently, the exact role of diatoms in controlling soil strength and underlying mechanisms remain obscure. Here, the frictional strength of diatomaceous soil is evaluated by way of angle of repose and direct simple shear tests on diatom–kaolin mixtures with differing diatom content. The microscale and nanoscale structures are characterised in detail using scanning electron and atomic force microscopy to establish how soil structure evolves with diatom content and shear. For the studied diatom–kaolin mixtures, the angle of repose and internal frictional angle are high and increase with diatom content, especially when the diatom content exceeds 20%. Diatom content controls the frictional strength through its intricate morphology (cylindrical, saucer and disc shapes), very rough surface (hundreds of times rougher than flaky minerals) and stiff frustules with high Young's modulus. These features increase the particle coordination number and produce interparticle interlockings, both of which prevent particle rearrangement during shear and improve the frictional strength. This paper provides new insights into the multiscale structure of diatoms and improves understanding of the shear strength of diatomaceous soils.

Effect of Spark Plasma Sintering Temperature on the Microstructure and Thermophysical Properties of High-Silicon–Aluminum Composites

Spark plasma sintering is a process of rapid, low-temperature, and high-density sintering. Moreover, traditional sintering methods can solve the problems of large grain sizes and low densities. The sintering temperature plays a crucial role in influencing the physical properties of high-silicon–aluminum (Si-Al) composites. This work investigated the impact of temperature on the microstructure, interface, and physical properties of high-Si-Al composites by spark plasma sintering. The results demonstrate that when the powder was processed by ball milling at a sintering temperature of 565 °C, the material exhibited the densest microstructure with minimal pore formation. The average size of the silicon phase is the smallest. The material’s thermal conductivity is 134.6 W/m·K, the thermal expansion coefficient is 8.55 × 10−6 K−1, the Brinell hardness is 219 HBW, the density is 2.415 g/cm3, and the density reaches 97.75%. An appropriate sintering temperature facilitates particle rearrangement and dissolution–precipitation processes, enhancing the material structure and performance.

Effects of water on cold‐sintered highly dense dicalcium phosphate anhydrous bioceramic using its hydrate

AbstractThe dicalcium phosphate anhydrous (DCPA, CaHPO4) bioceramic has long been difficult to prepare by conventional sintering techniques due to its weak thermal stability. Here, the DCPA ceramic is prepared at 250°C by cold sintering process (CSP) using the dicalcium phosphate dihydrate (DCPD, CaHPO4·2H2O) as the starting powder. It is found that the dehydration temperature of DCPD powder is greatly reduced during CSP, which facilitates the densification even without additive water. However, the ceramic only reaches a relatively low density of around 90% without additive water, which can be ascribed to the lack of particle rearrangement and the readily loss of dehydration water during sintering. In comparison, a high relative density of 95% can be obtained when the DCPD hydrate is densified with additive water, in which both hydration water and additive water play important roles. The obtained DCPA ceramic with high density exhibits a flexural strength of 46.17 MPa and Young's modulus closer to human bones compared with hydroxyapatite. Combined with the low cytotoxicity, the DCPA bioceramic has great potential to be applied for bone tissue engineering.

Remarkably improved nonlinearity and thermal stability of CaYNbMnO7 thermosensitive ceramics via the cold‐sintering process

AbstractThe cold‐sintering process (CSP) uses a transient low‐temperature solvent, such as water or water with dissolved solutes consistent with the ceramic composition, to achieve functionalization at lower temperatures via the dissolution and precipitation principle. Here, during the CSP, the use of molten NaOH as a flux solvent promoted the rearrangement and precipitation of CaYNbMnO7 particles. CaYNbMnO7 ceramics were successfully obtained at 350°C and under a uniaxial pressure of 700 MPa. The ceramic was not a single‐phase structure but consisted of a cubic‐phase structure and a layered perovskite structure. To verify the high‐temperature thermal stability of CaYNbMnO7 ceramic prepared at 350°C, a comparative study was conducted with conventional sintering (CS). Results indicate that the ceramics obtained by CSP and CS have negative temperature coefficient characteristics. The cold‐sintered ceramic has a wider temperature range and better aging stability. (The minimum value of the aging coefficient is ∼2.49%.) Simultaneously, CSP is beneficial for promoting the linearization of the relationship between the logarithm in the resistivity (lnρ) and the reciprocal for the absolute temperature (1000/T) in the ceramic. However, the CSP has little effect on the material constant B and thermal activation energy Ea of the ceramic, providing a basis for the low‐temperature synthesis of high melting point thermosensitive ceramics.

Discrete element modeling of rock-filled gabions under successive boulder impacts

A discrete element model consisting of irregular crushable filling particles and a flexible wire mesh is established. The numerical model is validated against the static net punching test and the dynamic pendulum impact test to ensure that the large irreversible plastic deformations and the impact forces during successive impacts can be captured. The impact force reduces at small friction coefficients, which is associated with the significant particle rearrangement during the impact process. The important role of friction is further confirmed by the energy evolution, showing that friction is the dominant mechanism for energy dissipation, instead of the more intuitionistic collision or particle crushing. Besides, the increase of impact force with the number of impacts becomes more significant at a higher impact energy due to the faster rate of momentum exchange. A bounce-back behavior of the boulder is observed when the impact energy is low, which may attenuate the impact force like the reflection waves in real debris flow events where multiple boulders are present. Our results highlight the combined effects of contact properties and impact energy, which are valuable in the design of rigid barriers shielded by rock-filled gabions for hazard mitigation in engineering practice.

Particle motion and stress response interacted with machine activity: Railroad tamping strategy

Tamping is a vital maintenance activity to correct railroad track geometry by lifting, aligning, and levelling the track. Traditional tamping practices are often rather empirical and rely heavily on operator’s experience. Railroads have learned that improper tamping parameters impact ballast stability and cause quick track geometry deterioration. The purpose of this study is to investigate the effect of tamping parameters on ballast performance at the particle level, expecting to figure out the optimized tamping parameters to improve track quality. To achieve this objective, field tamping tests were conducted on Norfolk Southern Railway's mainline. In the tests, four tamping parameter combinations of squeeze time (0.6 s, 1.0 s) and number of squeezes (1 insertion, 2 insertions) were executed by Plasser’s tamper. In addition, “SmartRocks” sensors were preinstalled under the ties to record ballast and contact stresses caused during and after tamping. It was found that 1.0 s squeeze time results in a more compact and stable ballast status than 0.6 s squeeze time, with a more stable rearrangement of particles and stable bulk stress after tamping. employing two insertions appeared to neutralize the impact of squeeze time duration, given a small lifting value of 25 mm. These findings provide insights into optimizing tamping strategies to improve the stability and durability of railroad tracks.

Arrhenius temperature dependence of the crystallization time of deeply supercooled liquids

Usually, supercooled liquids and glasses are thermodynamically unstable against crystallization. Classical nucleation theory (CNT) has been used to describe the crystallization dynamics of supercooled liquids. However, recent studies on overcompressed hard spheres show that their crystallization dynamics are intermittent and mediated by avalanchelike rearrangements of particles, which largely differ from the CNT. These observations suggest that the crystallization times of deeply supercooled liquids or glasses cannot be described by the CNT. However, this point has not yet been studied in detail and this situation leads to a lack of understanding of glass-forming ability. In this paper, we use molecular dynamics simulations to study the crystallization dynamics of soft spheres just after an instantaneous quench. We show that although the equilibrium relaxation time increases in a super-Arrhenius manner with decreasing temperature, the crystallization time shows an Arrhenius temperature dependence at very low temperatures. This is contrary to the conventional formula based on the CNT. Furthermore, the estimated energy barrier for the crystallization is surprisingly small compared to that for the equilibrium dynamics. By comparing the crystallization and aging dynamics quantitatively, we show that a coupling between aging and crystallization is the key for understanding the rapid crystallization of deeply supercooled liquids or glasses. Published by the American Physical Society 2024

Shape anisotropy induced jamming of nanoparticles at liquid interfaces: a tensiometric study.

The intersection of nanotechnology and interfacial science has opened up new avenues for understanding complex phenomena occurring at liquid interfaces. The assembly of nanoparticles at liquid/liquid interfaces provides valuable insights into their interactions with fluid interfaces, essential for various applications, including drug delivery. In this study, we focus on the shape and concentration effects of nanoscale particles on interfacial affinity. Using pendant drop tensiometry, we monitor the real-time interfacial tension between an oil droplet and an aqueous solution containing nanoparticles. We measure two different types of nanoparticles: spherical gold nanoparticles (AuNPs) and anisotropic gold nanorods (AuNRs), each functionalized with surfactants to facilitate interaction at the interface. We observe that the interface equilibrium behaviour is mediated by kinetic processes, namely, diffusion, adsorption and rearrangement of particles. For anisotropic AuNRs, we observe shape-induced jamming of particles at the interface, as evidenced by their slower diffusivity and invariant rearrangement rate. In contrast, the adsorption of spherical AuNPs is dynamic and requires more time to reach equilibrium, indicating weaker interface affinity. By detailed analysis of the interfacial tension data and interaction energy calculations, we show that the anisotropic particle shape achieves stable equilibrium inter-particle separation compared to the isotropic particles. Our findings demonstrate that anisotropic particles are a better design choice for drug delivery applications as they provide better affinity for fluid interface attachment, a crucial requirement for efficient drug transport across cell membranes. Additionally, anisotropic shapes can stabilize interfaces at low particle concentrations compared to isotropic particles, thus minimizing side effects associated with biocompatibility and toxicity.

Clogging and Unclogging of Fine Particles in Porous Media: Micromechanical Insights From an Analog Pore System

AbstractPore clogging and unclogging in porous media are ubiquitous in subsurface hydrologic processes, which have been studied extensively at various scales ranging from a single pore to porous‐medium samples. However, it remains unclear how fluid flow, particle rearrangement, and the arching effect typical of cone‐shaped pore geometry interact and how they are captured by a pressure drop model at the macroscopic scale. Here, we investigate the pore‐scale feedback mechanisms between fluid flow and pore clogging and unclogging using a fully resolved fluid‐particle coupling approach (lattice Boltzmann method‐discrete element method). We first propose to use a truncated‐cone pore to represent realistic pore geometries revealed by X‐ray images of prepared sand packing. Then, our simulations indicate that the pore cone angle significantly influences the pressure drop associated with the clogging process by enhancing particle contacts due to arching. A modified Ergun equation is developed to consider this geometric effect. At the microscale, clogging can be explained by the interparticle force statistics; a few particles in an arch (or a dome) take the majority of hydrodynamic pressure. The maximum interparticle force is positively proportional to the particle Reynolds number and negatively associated with the tangent of the pore cone angle. Finally, a formula is established utilizing fluid characteristics and pore cone angle to compute the maximal interparticle force. Our findings, especially a modified pressure drop model that accounts for pore geometry resistance, provide guidance for applying pore‐scale models of clogging and unclogging to large‐scale subsurface fines transportation issues, including seepage‐induced landslides, stream bank failure, and groundwater recharge.

Thin free-standing liquid films manipulation: device design to turn on/off gravity in flow regimes for thickness map control and for material structuring.

The manipulation and control of free-standing liquid film drainage dynamics is of paramount importance in many technological fields and related products, ranging from liquid lenses to liquid foams and 2D structures. In this context, we theoretically design and introduce a device where we can reversibly drive flow regime switch between viscous-capillary and viscous-gravity in a thin free-standing liquid film by altering its shape, allowing us to manipulate and stabilize the film thickness over time. The device, which mainly consists of a syringe pump, a pressure transducer, and a 3D-printed cylinder, is coupled with a digital holography setup to measure, in real time, the evolution of the local film thickness map, revealing characteristic features of viscous-capillary and viscous-gravity driven drainage regimes. By using polyvinyl alcohol/water concentrated solutions, we are also able to produce viscoelastic membranes after manipulation and water evaporation, which presents manipulation history-dependent geometrical properties. Furthermore, using a system composed of carboxymethyl cellulose, water, and rod-like zinc oxide nanoparticles, we show a clear effect of film manipulation on particle rearrangement. We believe this device could represent a starting point for the development of a useful and practical tool to study thin liquid film dynamics and to produce novel (patterned) 2D structures for the numerous scientific and technical fields where they are of use.

Effects of vegetation on the hydro-mechanical properties of the vadose zone

The hydro-mechanical properties of the vadose zone are strongly influenced by seasonal cycles. The hydraulic behavior of this zone is determined by the coupling of biotic and abiotic factors. The biotic factors are controlled by the physiology and anatomy of the vegetation growing in the area, while the abiotic factors depend on the local soil characteristics, such as water content, void ratio, and matrix structure. In this laboratory-scale investigation, we assess the influence of active biomass, water content, and suction on the particle and pore structure rearrangement. We use x-ray computed tomography and 3D digital image correlation to quantify plant roots at different stages of growth, soil deformation, and water content fluctuations. Our results show that the bulk porosity of vegetated soil is strongly affected by the induced water cycles. The global micro-structure rearrangement due to the double effects of plant water uptake and induced drying-wetting cycles translates into a final bulk porosity increase.

Instantaneous normal modes of glass-forming liquids during the athermal relaxation process of the steepest descent algorithm.

Understanding glass formation by quenching remains a challenge in soft condensed matter physics. Recent numerical studies on steepest descent dynamics, which is one of the simplest models of quenching, revealed that quenched liquids undergo slow relaxation with a power law towards mechanical equilibrium and that the late stage of this process is governed by local rearrangements of particles. These advances motivate the detailed study of instantaneous normal modes during the relaxation process because the glassy dynamics is considered to be governed by stationary points of the potential energy landscape. Here, we performed a normal mode analysis of configurations during the steepest descent dynamics and found that the dynamics is driven by almost flat directions of the potential energy landscape at long times. These directions correspond to localized modes and we characterized them in terms of their statistics and structure using methods developed in the study of local minima of the potential energy landscape.

Energy processes and phase transition in granular assemblies

Granular assemblies are an illustrative example of complex material where unexpected macroscopic properties may emerge when they are subjected to a given loading. The complexity is the consequence of the huge geometrical disorder governed by particle rearrangements, entailing plastic dissipation at contacts. This local dissipation, associated with the global geometric disorder, is probably a key ingredient responsible for various macroscopic features, such as the strain localization in dense granular assemblies leading to the formation of a shear band. Based on a discrete element method (DEM), this manuscript investigates the energy processes at the microscopic scale in granular assemblies along biaxial loading paths for dense and loose assemblies. The localized shear band domain in a dense specimen is inspected. The analysis of elastic processes suggests a maximum capacity for storing elastic energy, giving rise to a phase transition from a homogeneous state to a heterogeneous one. This phase transition is marked by a significant release of elastic energy associated with plastic dissipation. The elastic-to-plastic energy transfer is shown to be a key ingredient to reach the stationary state regime characterized by a unique dynamic equilibrium. It is signaled by the constant ratios of elastic storage and plastic dissipation over the available energy, whatever the initial density of granular assemblies. Finally, the energy processes inside the shear band domain are shown to be largely dominated by intense plastic dissipation. This suggests that the shear band acts as an optimal dissipative structure in dense specimens where elastic mechanisms continue to be active at a much higher level than they are in the outside shear band domain.

Compression cycling and magnetic response of single crystalline Ni-Mn-Ga particles/polymer composite: In-situ and ex-situ study

Ni-Mn-Ga particles/polymer composites are new magnetostrain active materials suitable for actuation and sensing. In the present work, we prepared mechanically anisotropic samples of the “30 vol% single crystalline Ni-Mn-Ga particles/silicone” composite material and systematically studied their cyclic stress-strain (S-S) evolutions along and perpendicular to the particle chains, while monitoring changes of magnetization curves. Four different compression cycling routes with the strain amplitude of 30% were explored. Magnetic measurements were served as the probes to indirectly detect microstructure changes of composite samples, whereas X-ray micro-CT images, alongside dimensions control of samples, were used for direct microstructural observations. The influences of the compression cycling routes on the parameters of S-S behaviors, such as an output stress, effective stiffness, and stress hysteresis, were revealed. It was found that the composite material after achieving equilibrium showed a rather good compression cycling stability of the mechanical and magnetic properties. It was revealed that composites being strongly deformed either along easy-magnetization axis (along the particle chains) or along hard-magnetization axis (perpendicularly to the particle chains) exhibited a magnetically harder behavior along the particle chains and magnetically easier behavior in the orthogonal direction, respectively. These unusual effects of a strong deformation of composite on its magnetization processes were discussed in terms of the particle rearrangements in the chains.

Effect of sintering aids content and powder characteristics on gas pressure sintered Si3N4 ceramics

The Si3N4 raw powder, sintering aids, and sintering process are the most critical factors affecting the thermal conductivity and mechanical properties of Si3N4 ceramics. The impact of sintering aids content and powder characteristics on gas pressure sintered Si3N4 ceramics was investigated in this study. Lower aids content facilitated phase transformation prior to densification, promoting a pronounced bimodal microstructure. Based on in-situ shrinkage behavior, liquid phase sintering of Si3N4 ceramics can be divided into three stages without clear boundaries. Between 1200 and 1400 °C, higher oxygen and metallic impurities favored particle rearrangement. Between 1400 and 1800 °C, the dissolution and precipitation process was probably controlled by the α-phase ratio and particle size. Above 1800 °C, subsequent grain growth was primarily facilitated by the Ostwald ripening process, leading to a reduced densification rate. Higher oxygen content leading to greater weight loss during sintering. Higher Fe resulted in a darker color of sintered Si3N4 ceramics. High α-phase content promoted the formation of a bimodal microstructure and ensured superior mechanical properties. Reduced levels of oxygen and aluminum were prerequisites for achieving high thermal conductivity. Powders prepared by silicon nitriding method were cost-effective materials for the preparation of high-performance Si3N4 ceramic substrates.

Influence of Sphericity on Surface Termination of Icosahedral Colloidal Clusters.

Colloids self-organize into icosahedral clusters composed of a Mackay core and an anti-Mackay shell under spherical confinement to minimize the free energy. This study explores the variation of surface arrangements of colloids in icosahedral clusters, focusing on the determining factors behind the surface arrangement. To efficiently assemble particles in emulsion droplets, droplet-to-droplet osmotic extraction from particle-laden droplets to salt-containing droplets is used, where the droplets are microfluidically prepared to guarantee a high size uniformity. The icosahedral clusters are optimally produced during a 24-h consolidation period at a 0.04m salt concentration. The findings reveal an increase in the number of particle layers from 10 to 15 in the icosahedral clusters as the average number of particles increases from 3300 to 11 000. Intriguingly, the number of layers in the anti-Mackay shells, or surface termination, appears to more strongly depend on the sphericity of the clusters than on the deviation in the particle count from an ideal icosahedral cluster. This result suggests that the sphericity of the outermost layer, formed by the late-stage rearrangement of particles to form an anti-Mackay shell near the droplet interface, may play a pivotal role in determining the surface morphology to accommodate a spherical interface.

Programming and Reprogramming the Viscoelasticity and Magnetic Response of Magnetoactive Thermoplastic Elastomers.

We present a novel type of magnetorheological material that allows one to restructure the magnetic particles inside the finished composite, tuning in situ the viscoelasticity and magnetic response of the material in a wide range using temperature and an applied magnetic field. The polymer medium is an A-g-B bottlebrush graft copolymer with side chains of two types: polydimethylsiloxane and polystyrene. At room temperature, the brush-like architecture provides the tissue mimetic softness and strain stiffening of the elastomeric matrix, which is formed through the aggregation of polystyrene side chains into aggregates that play the role of physical cross-links. The aggregates partially dissociate and the matrix softens at elevated temperatures, allowing for the effective rearrangement of magnetic particles by applying a magnetic field in the desired direction. Magnetoactive thermoplastic elastomers (MATEs) based on A-g-B bottlebrush graft copolymers with different amounts of aggregating side chains filled with different amounts of carbonyl iron microparticles were prepared. The in situ restructuring of magnetic particles in MATEs was shown to significantly alter their viscoelasticity and magnetic response. In particular, the induced anisotropy led to an order-of-magnitude enhancement of the magnetorheological properties of the composites.

Thermo-mechanical behaviour of a kaolin-based clay soil

The thermal behaviour of KSS, a low-plasticity artificial clay made with kaolin clay, silt and sand, was investigated in a series of temperature-controlled oedometer tests, at temperatures between 5°C and 70°C, and at vertical pressures up to 2·4 MPa. The experiments investigated the effect of overconsolidation ratio (OCR), pressure level and repeated thermal cycling on thermally induced volume change. Thermal volumetric strains were found to be dependent not only on OCR but also on pressure level, contradicting previous experimental findings and highlighting the importance of even a small dependency of compression index Cc on temperature. Furthermore, thermal volumetric strains were irreversible on heating and cooling even for highly overconsolidated samples. Although irreversibility at high OCR values has been attributed to particle rearrangement and plastic accommodation in the past, an alternative explanation is put forward here, as yielding on the Hvorslev surface is expected to occur on unloading under one-dimensional (1D) conditions. The tests also revealed evidence of thermal creep for the initially normally consolidated samples. The influence of both current temperature and temperature history on the reloading response of mechanically overconsolidated KSS was tested and quantified in terms of their effect on the measured pre-consolidation pressure. The results from these tests were compared to results from the available literature referring to clays of similar and higher plasticity and the comparison highlighted that although soil plasticity can explain the observed quantitative differences between high-plasticity soils to a large extent, mineralogy, in addition to structure, may also play an important role for low-plasticity soils.

Strain rate effects on intact deep-sea sediments under different confining pressures and overconsolidation ratios

Underwater construction has gone to greater depths below the sea level for the extraction of resources such as oil and minerals. During different construction stages of deep-sea structures, different loading rates may be applied to deep-sea sediments. Generally, the strength of soil usually increases with the loading rate, and the sensitivity to strain rate effects may be more pronounced in deep-sea sediments. Previously, the strain rate effects were mainly studied on shallow marine deposits, but rarely on deep-sea sediments due to the difficulty of sampling. In this study, the strain rate effects on intact deep-sea sediments were investigated by a series of undrained triaxial tests with different strain rates of 0.5%/h, 2.6%/h and 13.2%/h under normally and over-consolidated conditions. In addition, scanning electron microscopy (SEM), nitrogen adsorption (NA) and mercury intrusion porosimetry (MIP) tests were conducted to illustrate the unique microstructure and pore size distributions of the deep-sea sediments, which showed a flocculent structure with abundant mesopores and macropores. It is found that higher strain rate leads to higher undrained shear strength due to the delay of increase of excess pore pressure as a result of low permeability. Strain rate effects are more obvious with the increase of confining pressure and then become less significant when the confining pressure is increased further. This change of trend is attributed to the increase of particle contact and more particle rearrangements when the confining pressure is first increased, but the particle rearrangement is suppressed under higher confining pressure. The sensitivity to strain rate effects increases with the overconsolidation ratio as more particle rearrangement is enabled under less confinement.

Characteristics and Controlling Factors of Particle Crushing in Volcaniclastic Sediments under Compaction: The Quaternary Pyroclastic Deposits of Hongtu Hill, Changbaishan Area, Northeastern China

Recently, many scholars have conducted experimental mechanical compaction studies on sandstones, carbonates, and mudstones to visually study the mechanical compaction process and reservoir evolution of sedimentary rocks. However, experimental mechanical compaction studies on the evolution of the compaction process of pyroclastic rocks have been ignored. Volcaniclastic rock reservoirs are widely distributed across the world and strongly influenced by the crushing of pyroclastic particles. In this study, we analyzed the characteristics and controlling factors of the crushing of pyroclastic particles during compaction diagenesis from a microscopic perspective through experimental mechanical compaction. These results can provide quantitative compaction background parameters for the quantitative study of pyroclastic rock reservoir evolution. We took pyroclastic samples from Hongtu Hill in the Changbaishan area as an example, and experimental mechanical compaction experiments were conducted. Furthermore, image surface porosity and particle analysis statistical methods were used, and the variations in the effective porosity and image surface porosity under different axial stresses were studied. The results showed that, after compaction, the effective porosity did not exhibit a decreasing trend with increasing axial stress but rather a normal distribution trend that initially increased and then decreased. In the compaction experiment, the pyroclastic particle crushing process was segmented with increasing axial stress, and there was an obvious compaction band in the initial stage of the compaction, called the particle rearrangement stage (10–30 MPa). Furthermore, there were relatively non-successive compaction localization areas in the later stage of compaction, called the particle crushing stage (50–70 MPa), which was represented by vitreous basalt particles surrounded by porphyritic basalt particles. During experimental mechanical compaction, the smaller the compactness, the smaller the solidity, and the larger the slenderness of the particles, the more likely the particles were to break during compaction. Particles containing intragranular pores and vitreous basalt particles were easily crushed.