Changes In Grain Size Distribution Research Articles

A simple gradation-state-dependent model for granular materials

This paper proposes a gradation-state-dependent constitutive model to capture the granular materials' mechanical behaviours considering the granular crushing's influence. Firstly, a gradation evolution law is developed to reflect the change in grain size distribution (GSD) with the growth of stress levels, and then, based on the evolution law, the elastic compliance matrix is modified to reflect the effects of particle breakage. Secondly, as the critical state line (CSL) exhibits gradation dependence, a novel method is developed to describe the family of CSLs under different fixed gradations. Subsequently, by combining the gradation evolution law with the CSL equation, the paper explains the steepening of the slope of the critical state line when the crushing is activated. With the improvement of CSL, the material's shear dilatancy and contraction properties are better reflected, assisting in establishing a plastic compliance matrix. Employing the derived elastic and plastic compliance matrix, the elastic–plastic model reflecting the influence of gradation and state effects is established and verified with a series of experimental and discrete element method (DEM) simulation results.

Unraveling grain growth of metallic tungsten: Investigating the nanoscale realm of hydrogen reduction of tungsten oxides

This paper focuses on the experimental observation of tungsten grain evolution during the process of hydrogen reduction of tungsten trioxide. The objective is to gain insights into the grain size distribution (GSD) evolution and morphology changes of metallic tungsten. The study employs an amalgamation of conventional characterization techniques – such as TGA, SEM-EDS, TEM and XRD – alongside cutting-edge techniques like phase contrast nano-tomography from synchrotron sources. Conducted as a quasi in-situ study, this research offers the opportunity to observe the transient evolution of the formed metallic tungsten phase within its precursor WO2 particles. The paper presents and discusses quantitative results concerning the evolution of GSD and morphological changes, encompassing growth rates of both crystallites and grains of the synthesized metallic phase. Additionally, the quasi in-situ study highlights the dependence of grain size on water concentration during the reduction process. The qualitative and quantitative findings contribute to a more nuanced understanding of the kinetics of grain growth of metallic tungsten and offer insights into the intricate interplay between reduction parameters, GSD evolution and morphological changes. Gaining a deeper understanding of the underlying mechanisms driving the changes in GSD establishes a foundation for predictive theory with immediate academic and industrial impact.

Clues of wildfire-induced geotechnical changes in volcanic soils affected by post-fire slope instabilities

Wildfires can significantly affect mountain hillslopes through the combustion of trees and shrubs and changes in soil properties. The type and magnitude of the associated post-fire effects depend on several factors, including fire severity and soil physical–mechanical-hydraulic features that, coupled with climate and topographic conditions, may cause increased runoff, erosion, and slope instability as consequence of intense rainfall. The post-fire response of slopes is highly site-specific. Therefore, in situ surveys and laboratory tests are needed to quantify changes in key soil parameters. The present study documents the post-fire physical and hydromechanical properties of pyroclastic topsoil collected from three test sites that suffered wildfires and rainfall-induced post-fire events in 2019 and 2020 in the Sarno Mountains (Campania Region, southern Italy). The tested pyroclastic soils in burned conditions show (i) no significant changes in grain size distribution, soil organic matter, and specific gravity; (ii) a deterioration in shear strength in terms of decreased soil cohesion caused by the fire-induced weakening of root systems; and (iii) a decrease in hydraulic conductivity. Accordingly, it can be argued that the documented post-fire erosion responses were mainly caused by the reduced cohesion and hydraulic conductivity of the burned topsoil layer, as well as by the loss of vegetation cover and the deposition of fire residues. Although deserving further deepening, this study can represent the necessary background for understanding the initiation mechanism of post-fire erosion processes in the analyzed area and on several natural slopes under similar conditions.

Estimation of shallow subsurface structures on granitic hillslopes based on electrical resistivity distribution

Electrical resistivity (ER) survey is an efficient method for investigating subsurface structure without destruction. However, this has not been used for estimating shallow subsurface zones of hillslopes that is related to the occurrence of shallow landslides. If the ER survey can alter conventional methods such as cone penetration test and boring to investigate soil thickness, an effective method for detecting landslide-prone area would be developed. In this study, ER survey was conducted on two granite hillslopes in Japan with low soil-moisture conditions to verify the usefulness of the ER survey to estimate the shallow subsurface structures. To compare the subsurface structure and the ER distribution, sounding by using a boring stick and a cone penetrometer were conducted along each ER survey line. Two soil pits were also referred near the survey lines. The subsurface structures were composed of topsoil, saprolite, and bedrock in our study sites. Results of ER survey with the unit electrode spacing of 0.5 m demonstrated that the ER increases with depth at the depths of the bottom of the topsoil layers, but the ER values were unconstrained. Below the bedrock surface, the ER generally decreased with depth, showing low ER less than 12800 Ω·m excepting an exposed bedrock indicating more than 20000 Ω·m. These spatial changes in ER are consistent with changes in grain size distribution and electrical conductivity of soil of each subsurface layer measured in this study and literature on ER of granite. ER distribution can visualize shallow subsurface structures and potential sliding surfaces for shallow landslides because the bottom of topsoil layer that was successfully estimated exhibits a discontinuity of shear strength, which generally corresponds to sliding surfaces for shallow landslides. Therefore, ER survey is applicable as an alternative to conventional methods for estimating shallow subsurface structures on granite hillslopes. Furthermore, ER survey can be a useful tool to estimate where shallow landslides will occur and how we should assess the risks of landslide hazards if a targeted subsurface zone has a distinct contrast in physical properties between each layer.

Experimental Study on the Effect of Freeze—Thaw Cycles on the Mineral Particle Fragmentation and Aggregation with Different Soil Types

The freeze–thaw cycle can change the size and shape of soil particles, that is, cause fragmentation and aggregation of soil mineral particles, thereby affecting the soil structure, which, in turn, affects the soil properties. In addition, the process of soil mineral fragmentation and aggregation, as an event closely related to the cold climate, plays an irreplaceable role in reconstructing the climatic conditions of a certain area and a certain period of time and has important referential significance for the restoration of historical permafrost boundaries and the study of climate change. Therefore, in order to better study the effect of freeze–thaw cycles on the fragmentation and aggregation of soil mineral particles, four soil specimens were selected for this study; the freeze–thaw cycle tests were carried out 0, 3, 6, 9, 50, and 100 times, respectively, and the test results were analyzed. The results of these experiments indicate that (1) after freeze–thaw cycles, the changes in grain-size distribution are different in various soil types, and the changes are mainly concentrated in 0.001–0.1 mm; (2) the coarse particle size particles (sand, silt) can be fragmented into relatively fine-grained particles (silt, clay). The fine-grained particles (clay) cannot undergo fragmentation, and the decrease in clay is due to its aggregation; (3) with the increase in freeze–thaw cycles, the fraction change trend of four specimens is parallel to the x-axis, which means the fragmentation and aggregation of soil mineral particles are in a state of equilibrium or balance; (4) the increase in the Kvar value indicates the change in grain-size distribution, which means aggregation and fragmentation of soil mineral particles. After the 100th cycle, the Kvar value of four specimens is <0.1, which belongs to a low-intensity area; (5) the freeze–thaw cycle will change the type of soil, and after 100 freeze–thaw cycles, the soil type of specimen (H) changes from silty clay loam to silty clay; (6) during the freeze–thaw process, different types of soil have different situations of aggregation and fragmentation.

Impact of Jordanelle Dam on sedimentological and ecohydrological regimes of the Provo River, Utah, USA

ABSTRACT The impact of large dams primarily built in the 1950s and 1960s has been extensively studied; more recent dam construction often occurs alongside habitat restoration activities, which have the potential to mitigate impacts. Jordanelle Dam on the Provo River, constructed in 1992, is economically and ecologically important to the region. This study aims to elucidate the effects of the dam on the sediment distribution and mobility of the river to inform future management of the system. Due to decreased flows, gravels (D16, D50) downstream of the dam are generally larger and subsurface grains are significantly coarser (p < 0.05), than those upstream of the dam. Further, the flow required to mobilize sediment is larger downstream of the dam and occurs rarely, leading to less mobile sediment and a more stable channel. The reduced mobility of sediment below the dam has decreased channel complexity. Much of the mobile sediment below the dam may be supplied from an unaltered river reach, rather than upstream mobilization. This sediment is vital to trout habitat, an important aspect of the recreation economy of the region. Monitoring changes in grain size distribution below the dam is necessary to prevent the loss of this valuable resource through diminished spawning habitat.

PLUME-MoM-TSM 1.0.0: a volcanic column and umbrella cloud spreading model

Abstract. In this paper, we present a new version of PLUME-MoM, a 1-D integral volcanic plume model based on the method of moments for the description of the polydispersity in solid particles. The model describes the steady-state dynamics of a plume in a 3-D coordinate system, and a modification of the two-size moment (TSM) method is adopted to describe changes in grain size distribution along the plume, associated with particle loss from plume margins and with particle aggregation. For this reason, the new version is named PLUME-MoM-TSM. For the first time in a plume model, the full Smoluchowski coagulation equation is solved, allowing us to quantify the formation of aggregates during the rise of the plume. In addition, PLUME-MOM-TSM allows us to model the phase change of water, which can be either magmatic, added at the vent as liquid from external sources, or incorporated through ingestion of moist atmospheric air. Finally, the code includes the possibility to simulate the initial spreading of the umbrella cloud intruding from the volcanic column into the atmosphere. A transient shallow-water system of equations models the intrusive gravity current, allowing computation of the upwind spreading. The new model is applied first to the eruption of the Calbuco volcano in southern Chile in April 2015 and then to a sensitivity analysis of the upwind spreading of the umbrella cloud to mass flow rate and meteorological conditions (wind speed and humidity). This analysis provides an analytical relationship between the upwind spreading and some observable characteristic of the volcanic column (height of the neutral buoyancy level and plume bending), which can be used to better link plume models and volcanic-ash transport and dispersion models.

Lithological indicators of discontinuities in mountain soils rich in calcium carbonate in the Polish Carpathians

Six soils located within the Polish Carpathians, developed on calcium carbonate–rich sedimentary parent materials and representing various reference groups, were investigated in order to detect the lithic discontinuity. We propose using a multidirectional approach to assess the lithic discontinuity in these soils, one that includes grain size distribution, geochemical composition, heavy mineral content and micromorphology, supported by a traditional soil survey. A further aim of this process was to identify the possible admixture of allochthonous material of aeolian origin. The studied soils presented lithic discontinuities mostly at the contact of underlying calcium carbonate–rich coarsegrained slope deposits with the overlaying colluvium layer having a lower content of rock fragments. The significant changes in grain size distribution, especially in the silt and sand content, as well as high Uniformity Values and partially, high Lithological Discontinuity Index values, confirmed the occurrence of a lithic discontinuity in all studied soils. High heterogeneity in the soil profiles was also confirmed by the distribution of the major oxides; however, their distribution did not clearly indicate the lithic discontinuity. The most visible distinctions were noted from CaO content, which resulted from the deposition of carbonate-free materials (aeolian silts) and their mixing with the calcium carbonate–rich parent material. Furthermore, the analysis of heavy mineral content confirmed the allochthonous origin of the upper (and in some cases also the middle) parts of all profiles, which was manifested by the presence of highly weathering-resistant minerals such as zircon, epidote and various types of garnets. The micromorphological features of some of the studied soils showed distinctiveness within the soil profile, manifested by changes in b-fabric pattern, the occurrence and distribution of secondary carbonate and the coarse and fine coarse and fine ratio. Based on the high content of silt within the upper and middle parts of the soils, the content of Hf and Zr, as well as the higher content of weathering-resistant minerals, admixture of aeolian silt could be considered in some of the studied soils, yet with weak character. However, the dominance of minerals typical for metamorphic and igneous rocks suggested that the supply of aeolian silt was associated with loess covers rather than local sedimentary material.

Experimental investigation into non-collapsible loess-like soil's engineering geological properties under the influence of freeze–thaw cycles

Recurrent freeze–thaw cycling is a powerful weathering process that subjects soil to frost heave and thaw settlement. The cycling significantly changes the soil structure and leads to particle recombination, ultimately causing deterioration of the soil's properties. Herein, we investigated the effect of freeze–thaw cycles on loess-like soil in seasonally frozen regions; specifically with respect to the engineering geological properties, such as changes in grain-size distribution, liquid–plastic limit and collapse behaviour. The results indicate that over the course of 20 freeze–thaw cycles, the soil samples’ dry density decreased, the particle diameter of each soil fraction changed in a bi-directional manner (large particles were broken into finer sizes and fine particles agglomerated into larger particles), and the liquid limit and plasticity index first increased and then decreased. An increase in the initial water content resulted in more significant changes. In contrast to the undisturbed soil samples, the freeze–thaw cycles caused non-collapsible remoulded loess-like soil to collapse. Furthermore, microscopic evaluation allowed us to determine the collapse mechanism. Essentially, after the freeze–thaw cycles, the quantity of micropores in the soil decreased, whereas that of medium pores and macropores significantly increased. In addition, a trellis structure, similar to the typical loess structure, was generated.

Low-temperature dielectric anomalies in KSr2Nb5O15 ceramics with tetragonal tungsten bronze structure: The effect of microstructure

The dielectric behaviors of the tetragonal tungsten bronze (TTB) structured ceramics have been extensively studied by doping other elements due to their compositional flexibility. The microstructure of ceramics will inevitably vary with the change of chemical composition. In order to clarify the microstructural effect, the dielectric properties of the KSr2Nb5O15 (KSN) ceramics with various grain microstructures were investigated. Successful preparation of the KSN ceramics with same chemical compositions and different microstructures could be attributed to the usage of microcrystalline powder with different particle size distributions. It was found that the dielectric characteristics varied significantly with microstructures of the KSN ceramics. A new low-temperature dielectric anomaly appeared in the ceramics with a duplex structure. In addition, the peak shifted with the change of grain size distribution. These results suggested that the microstructural influence should not be neglected for the studies of the origin of the dielectric anomalies in TTB structured ceramics.

Effects of river infrastructures on the floodplain sedimentary environment in the Rhône River

River infrastructures such as dikes, groynes, and dams are ubiquitous on most large rivers, and although their consequences on the riverbed morphology have often been studied, the effect they might have on the river floodplain and margins remains largely unknown. By investigating the structure and composition of floodplain sediments in three areas along the Rhone River that were extensively engineered during the last 150 years, this paper aims to understand whether river infrastructures might systematically induce a change in sedimentation patterns in the river margins. A total of fifteen sediment cores were sampled in three distinct reaches of the Rhone valley downstream of Lyon. They were thoroughly analyzed in terms of grain size, using heatmap representations and end-member analysis. Six metallic elements (Zn, Cr, Pb, Cu, Ni, Cd) were systematically quantified. In six out of the fifteen cores, total organic carbon (TOC), organic contaminants (PCBs) concentrations, and 137Cs activity were also assessed. A sharp change in grain size distribution is consistently identified in the sediment cores of all three study reaches. The sediments above this change are fine (D50 < 100 μm), poorly classified and homogenous. They also show a relative increase in contamination when compared with deeper sediments. We interpret this change in sediment characteristics as the consequence of an abrupt decrease in connectivity between the floodplain and the river channel, likely due to the implementation of navigation infrastructures in the channel in the second half of the nineteenth century. In one case, the dating of the sediment cores allows linking the grain size change to the implementation of navigation infrastructures in the channel. In the other study areas, the effect of engineering seems delayed in time due to local variability. The implementation of river infrastructures resulted in a loss of connectivity between the floodplain and the channel. This was reflected as the homogenization of the floodplain sedimentary environment of the Rhone River all along its course from Lyon to the sea. A similar phenomenon might be present in most engineered rivers across Europe.

Modeling for critical state line of granular soil with evolution of grain size distribution due to particle breakage

Determination of the critical state line (CSL) is important to characterize engineering properties of granular soils. Grain size distribution (GSD) has a significant influence on the location of CSL. The influence of particle breakage on the CSL is mainly attributed to the change in GSD due to particle breakage. However, GSD has not been properly considered in modeling the CSL with influence of particle breakage. This study aims to propose a quantitative model to determine the CSL considering the effect of GSD. We hypothesize that the change of critical state void ratio with respect to GSD is caused by the same mechanism that influences of the change of minimum void ratio with respect to GSD. Consequently, the particle packing model for minimum void ratio proposed by Chang et al. (2017) is extended to predict critical state void ratio. The developed model is validated by experimental results of CSLs for several types of granular materials. Then the evolution of GSD due to particle breakage is incorporated into the model. The model is further evaluated using the experimental results on rockfill material, which illustrates the applicability of the model in predicting CSL for granular material with particle breakage.

A combined method to model grain crushing with DEM

This paper presents a combined method to model grain crushing effects with discrete element method. This method combines the two most commonly used concepts to model grain crushing in DEM, i.e. the replacement method and the agglomerate method, so that it is both accurate and efficient. The method can be easily implemented. The performance is shown by several DEM simulations of biaxial tests. Particles with different crush-abilities are modeled. DEM simulation results with and without grain crushing are compared and discussed. The change of grain size distribution due to grain crushing is also investigated.

Sedimentary environments and lithofacies distribution of zeit formation, red sea- Sudan

The Sudanese red sea coastal plain is geologically characterized by Cenozoic siliciclastic and shallow marine rift related sedimentary se-quences. Pliocene-Pleistocene is represented by the thick older gravel unit and the emergent linear reef terraces. In this study, wire line logs besides the investigations of cutting samples were used to investigate the un cored facies successions, to detect changes in grain size distribution, lithology and sedimentary facies and hence to interpret depositional environment. Confirmation of the log behavior using the cores and the cutting samples was undertaken. Furthermore, core to gamma-ray and spontaneous potential log correlations were set up. The lithofacies association and the depositional patterns of Zeit Formation were controlled by allocyclic and autocyclic processes, which include tectonic, palaeo climatic as well as depositional mechanisms. The lithofacies Distribution of Lower Zeit Member shows the southwestern part of the area is dominated by terrestrial to marginal marine partly supra tidal domain where some channel feeders can support the sand distribution from south to north. The central part of the area is dominated by shallow marginal marine to partly supra-tidal domains. The Middle Zeit Member was dominated by marginal marine to supratidal domain. The Upper Zeit Member repeated pattern of facies distribution being similar to that of Middle Zeit, however the sandy facies influxes increased towards the S. Suakin, Digna- area, towards Bashayer area and Durwara area from south to north.

Role of molybdenum trioxide in enhancing the humidity sensing performance of magnesium ferrite/molybdenum trioxide composite

In the present work, we prepared magnesium ferrite/molybdenum trioxide (MFMO) nanocomposite using mechano chemical mixing method for humidity sensor at room temperature. Enhancement in active sites for water adsorption in the composite due to the presence of MoO3 confirmed from X-ray diffraction (XRD) studies. Change in grain size distribution and increase in intergranular pores in the composite favouring water adsorption confirmed from its scanning electron microscopy (SEM) image. Increased agglomeration of nano sized particles and improved crystallinity of the composite confirmed from Transmission electron microscopy (TEM) studies and selected area electron diffraction (SAED) pattern. The composite showed maximum sensing response of 4902 as against 183 of MF in the range 11%–97% RH. The response and recovery times of the composite were found to be 45 s and 74 s respectively while those of MF 225 s and 364 s respectively. The nanocomposite sample showed stable humidity sensing ability and a low humidity hysteresis. Molybdenum trioxide plays a major role in enhancing the humidity sensing performance of MFMO composite at room temperature. The sensing mechanism discussed on the basis of chemisorptions, physisorption and capillary condensation processes.

CO2-brine-rock interactions: The effect of impurities on grain size distribution and reservoir permeability

The Bunter Sandstone formation in the UK’s southern North Sea has been identified as having the potential to store large volumes of CO2. Prior to injection, CO2 is captured with certain amounts of impurities, usually less than 5%vol. The dissolution of these impurities in formation water can cause chemical reactions between CO2, brine, and rock, which can affect the reservoir quality by altering properties such as permeability. In this study, we explored the effect of CO2 and impurities (NO2, SO2, H2S) on reservoir permeability by measuring changes in grain size distributions after a prolonged period of 9 months, simulating in situ experimental conditions. It was found that the effects of pure CO2 and CO2-H2S are relatively small, i.e., CO2 increased permeability by 5.5% and CO2-H2S decreased it by 5.5%. Also, CO2-SO2 slightly decreased permeability by 6.25%, while CO2-NO2 showed the most pronounced effect, reducing permeability by 41.6%. The decrease in permeability showed a correlation with decreasing pH of the formation water and this equally correlates with a decrease in geometric mean of the grain diameter. The findings from this study are aimed to be used in future modelling studies on reservoir performance during injection and storage, which also should account for the shifts in boundaries in the CO2 phase diagram, altering the reservoir properties and affecting the cost of storage.

Optimizing the Gradation of Fine Processed Reclaimed Asphalt Pavement and Aggregate Blends for Unbound Base Courses

The purpose of this research was to investigate the effect of changes in grain size distribution to the permanent deformation of two different fine processed reclaimed asphalt pavement (RAP) blended with base course virgin aggregate (VA). Grain size distribution of the RAP-VA blends were created following two different approaches. The first approach was based on mixing RAP and VA to have one grain size distribution, regardless of how much RAP was added to VA (here referred to as the engineered mixture design). The second approach was based on mixing RAP and VA with as-is gradation from the plants to proportions determined by weight and not controlling the outcome of the specific grain size of the mixture. This approach resulted in various grain size distributions (here referred as the as-is mixture design). The engineered mixture design was useful to quantify the effect of adding RAP to the blends, but was not a realistic approach to create blends that may be achieved in the field. The as-is mixture design could not only be achieved in the field, as demonstrated in this study, but also resulted in better performance in terms of permanent deformation. This manuscript describes the comparison of these two approaches and a methodology to optimize the gradation and develop thresholds for RAP-VA blends that may result in similar or better performance than the 100% as-is VA that is used to construct base course in pavement systems.

Heat treatment effects on mechanical properties of Ni–Co alloy thin films

ABSTRACTVertical type probe is made by microelectromechanical system (MEMS) process in microscale for high degree of integration and performance. To design reliable probe before manufacturing, mechanical properties in microscale is needed. Also, manufactured probe is heat-treated to release residual stress. In this paper, to understand mechanical properties and heat treatment effect in microscale, tensile tests for Ni–Co alloy thin film is performed using specimen with heat-treated under air. The Ni–Co thin film has some enhanced mechanical properties by heat effect and becomes brittle. The changes of grain size distribution and grain direction are observed through electron back-scattered diffraction (EBSD).

An Equilibrium Transport Formula for Modeling Sedimentation of Dredged Channels

The proposed formula for modeling sedimentation is based on a concept of hydrodynamic equilibrium in sediment transport. Hydrodynamic equilibrium occurs when the sediment transport is in a form of grain jumps with the distance traveled dx smaller than the one established in the numerical modeling. A first-order upwind scheme FDM is applied. It provides the solution to equations describing changes in bathymetry in time and space coupled with simultaneous changes of bed sediment distribution. A clear-cut division of sediment transport into those during wave crest and wave trough is proposed. The results of bathymetry modeling coincided satisfactorily with the laboratory data. Moreover, the longer the experiments run, the more the results of measurements are compliant with the calculations. A certain time is needed for sediment transport to reach the hydrodynamic equilibrium, especially when the suspended load is significant. It is reached after going through the initial stages of bed level changes coupled with simultaneous changes of grain size distribution. The application of the model to field conditions shows its ability to predict sedimentation of dredged channels. Furthermore, the calculations show a good agreement with measured bed grain size distributions of sediment samples taken from the sites within the navigational channel of Łeba Port in Poland.

Interactions between different acids and bauxitic-based ceramic proppants used in gravel-packed and fractured wells

Proppants are widely used in hydraulic fracturing operations. They consist of solid particles with specific strengths and are used to keep the fractures open to enhance well production. They can be natural sand or artificial ceramic materials. Most ceramic proppants are alumina-based, using kaolin and bauxitic clays as the raw materials. The acid resistance of the fracturing proppant is an essential property. Acids are sometimes needed to clean the fracture by removing scale and clays that reduce the fracture conductivity.In this study, several experiments were conducted using a see-through cell, and an aging cell with 10 wt% HCl, mud acids (6.0 wt% HCl, 1.0 wt% HF and 12.0 wt% HCl, 3.0 wt% HF), i.e., (6:1 and 12:3), and formic (HCOOH), trisodium salt of N-(hydroxyethyl)-ethylenediaminetriacetic acid (Na3-HEDTA) and HF mixtures up to 350 °F. The effects of varying acid system, temperature, soaking time, static and dynamic conditions were examined. The supernatant of solubility tests was analyzed with Fluorine Nuclear Magnetic Resonance (19F NMR) to identify the reaction products. Key elements concentrations were measured using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). A Zeiss Axiophot microscope was used to acquire images for the proppant particles to study particle shape and effect of acid solubility. Proppants were then analyzed by X-ray fluorescence (XRF) and X-ray diffraction (XRD). The proppant was sieved before and after the experiments. The residual solids were dried and analyzed using a scanning electron microscope (SEM) with Energy Dispersive X-ray Spectroscopy (EDS) capabilities. Effects of acid dissolution on mechanical performance of the proppants were also tested using an automated load frame.The results show that bauxite has a minimal solubility of 0.5 wt% in 10.0 wt% HCl. The proppant is readily soluble in different mud acids, 56.0 wt% dissolved in some cases. The amount dissolved increases with temperature, soaking time, acid concentration, and dynamic conditions. The fines generated and the changes in grain size distribution are detrimental to the proppant conductivity. 19F NMR showed aluminum fluoride complexes with different mud acids due to the high Al/F affinity. XRF showed that the solubility of the proppant occurs mainly in mullite and maghemite due to their high reactivity. Crush resistance test shows a direct relationship between solubility and mechanical strength of bauxite. Assessing solubility effects will help to better design acid treatments without jeopardizing the integrity of the proppant.