Particle Roundness Research Articles

Possible sources of ambient PM10 inside Jadavpur University Campus, Kolkata.

High concentration of particulates in the university and research institutional campus can affect cognitive performance of students and researchers. However, studies on ambient particulate concentration in the campus of universities or research institutes are scarce. The ambient concentration of PM10 was measured in the campus of Jadavpur University, Kolkata, during two different seasons (S1: Post-monsoon; S2: Winter) to identify major sources of pollutant here. Significant seasonal variation of ambient PM10 was recorded in the campus. The average ambient PM10 concentration was recorded higher in S2 compared to S1 of the study period. Morphological characteristics of PM10 during the study period suggest that the roundness of particles was in the range of 0.66 to 0.68, whilst the mean spherical diameter suggests most of the PM10 particles were < 2.5 μ diameter. Based on factorial analysis, three factors were generated which includes factor 1: soil, building material and coal burning particles (53.76% of the variance); factor 2: particles from coal combustion (29.89% of the variance) and factor 3: particles from transport emission (16.33% of the variance). The study suggests that it is important to stop burning coal, reduce vehicular emission and reduce road dust resuspension around the campus to maintain the ambient PM10 concentration within the university campus during the post-monsoon and winter months.

مقایسه تاثیر مکانیزم های شکست بر درجه آزادی و شکل ذرات در فلوتاسیون کانسنگ مس سولفیدی

A sulfide copper ore was crushed to 100% passing 3.36mm followed by grinding the crushed product through bed breakage process in a piston- die cell or ball mill into to 100% passing 250μm. Revealed by the results of particle size analysis made on the ground products, the bed breakage method provides a finer product compared to the ball mill approach. The liberation analysis of the products in eight size-fractions showed that the chalcopyrite in the ball mill product was more liberated compared to the bed breakage product. The overall percentage of chalcopyrite liberation in the ball mill product was higher than the bed breakage product by 1.82%. The shape properties of particles in the breakage products were examined by analysis of scanning electron (SEM) images. Accordingly, it was found that the circularity and roundness of particles broken by the bed breakage method are higher than the particles broken by the ball mill method, while the ball-milled particles are more elongated. The results of micro-flotation tests indicated the efficiency rate of Cu recovery and separation in the ball mill product were respectively 11% and 15% higher than the bed breakage product. This better metallurgical performance can be attributed to the fact that the bed breakage product was finer, the chalcopyrite was more liberated in the ball milling product, and particles in the ball milling product had less circularity and roundness. Contrary to many previous studies, the results of this study indicated that the bed breakage method did not increase the mineral liberation and improved the performance of the flotation process.

A novel deep learning-based modelling strategy from image of particles to mechanical properties for granular materials with CNN and BiLSTM

It will be practically useful to know the mechanical properties of granular materials by only taking a photo of particles. This study attempts to deal with this challenge by developing a novel deep learning-based modelling strategy. In this strategy, the convolutional neural network (CNN) as image identification algorithm is first used to extract the particle information (particle size distribution PSD and morphology) based on the image of a granular sample, and the bidirectional long short-term memory (BiLSTM) neural network is employed to train the model of reproducing mechanical behaviours and induced fabric evolutions of the sample with corresponding particle information. The datasets of images of samples are generated using discrete element method, and the datasets of mechanical properties together with fabric evolutions are obtained through numerical tests on corresponding samples. As a preliminary attempt, two-dimensional biaxial samples and tests with initially isotropic fabric are considered for the sake of simplicity. The feasibility and reliability of the proposed modelling strategy are evaluated through training and testing. All results indicate that the first part of the model based on CNN is capable of accurately identifying PSD of a granular sample, as well as circularity and roundness of particles, using which as connecting parameters the mechanical behaviours together with induced fabric evolutions of granular materials are subsequently well captured by the second part of the model based on BiLSTM. This study provides a basis and a possible way to obtain immediately particle and packing information, mechanical properties and fabric evolutions by leveraging images of granular materials.

DEM study on effect of particle roundness on biaxial shearing of sand

In this study, discrete element method (DEM) simulations of a biaxial test were used to examine the effect of particle roundness on the mechanical behavior of sands at both the macro and micro scales. First, a stack of microcomputed tomography images were binarized, segmented, and labeled using advanced image processing and analysis techniques. Second, a spherical harmonic (SH) analysis, which involves a complete set of orthogonal functions, was implemented to rebuild the natural particle shape. Then, five templates of virtual particles were built in a DEM simulation, four of which were obtained from SH degrees of 3, 8, 12, and 15, and one template was an elementary sphere. A flexible membrane was numerically generated to allow the material to deform freely under a prescribed confining stress. Finally, the effect of particle roundness on the mechanical properties of granular materials was investigated and discussed. Two shear bands were found to intersect, forming an X shape in both the rotation and displacement fields. Moreover, a lower particle roundness results in higher deviatoric stress and stronger dilation in the volumetric change. A decrease in particle roundness leads to less rotation of particles despite a higher displacement value. In addition, a larger SH degree leads to smaller normalized contact forces of the particles. This implies that decreasing the roundness results in higher anisotropy of the contact forces.

Photogrammetry based computational fluid dynamics of erosion of sand particles in water pipeline: Dynamic shape factors of 3D particles and minimization of erosion activity

Extraction and delivery of raw materials in engineering industries are inevitably polluted with sand particles that caused several flow assurance problems. Besides, designing a pipeline and estimating sand erosion is very complex in a multiphase flow due to several important factors needed to be considered, such as impact velocity, impact angle, size of particle, shape of particle, properties of particle, and properties of the target material. In this work, a modified E/CRC erosion model was developed to address the shape randomness in sand particles distribution. The photogrammetry technique was adopted to digitize sand particles into 3D models within the range of 400–500 μm. After quantitative and qualitative analysis, a database of shape factor for different spherical and roundness of sand particles was tabulated. Meanwhile, a high-fidelity simulation of a 90-degree elbow pipeline was conducted using the CFD-DEM method. Hydrodynamic characteristics of liquid flow, sand particle trajectories, the sensitivity of velocity, shape factor, and flow rate were comprehensively explored. Modification of the particle shape factor based on the generated database from photogrammetry resulted in overestimated erosion rate of the original E/CRC model with 124.4% accuracy improvement in predicting erosion rate on pipe bend at different collision angles. Lastly, through response surface methodology (RSM), a flow threshold condition was established to achieve minimum erosion damage.

Characteristics of the Coal Fines Produced from Low-Rank Coal Reservoirs and Their Wettability and Settleability in the Binchang Area, South Ordos Basin, China

By using proximate analysis, X-ray diffraction mineral analysis, scanning electron microscope, contact angle measurement, and settlement simulation experiment, the coal fines produced from the coalbed methane wells of Binchang area were used to study the characteristics including particle size distribution, composition, morphology, wettability, and settleability. The results show that the particle size of coal fines produced from coalbed methane wells are mainly &gt;20 mesh, ranging of 1-400 μm, and the particle size distribution curve is mainly dominated by the main-secondary bimodal type, with the main peak of 30-300 μm. The particle size from large to small is drill cutting coal fines, flowback coal fines, bailing coal fines, and pipeline filter coal fines. In terms of ash content, coal fines are higher than coal seam, and drilling cuttings are higher than bailing coal fines, while the fixed carbon content of the former is lower than that of the latter. The minerals of coal fines are mainly kaolinite, illite, quartz, and other 6 minerals, and the mineral types of drilling coal fines are the most abundant, while the bailing coal fines only contain illite and quartz. The roundness of coal fine particles ranges from excellent to poor in the order of bailing coal fines, pipeline filter coal fines, flowback coal fines, and drilling cuttings. However, the sorting of drilling cuttings is excellent, and the particle edges are straight, neat, and smooth, while the sorting of bailing coal fines is poor, and the particle edges are curved, uneven, and rough. The contact angles of coal fines are 40.25°-69.5°, indicating hydrophilous. The wettability of bailing coal fines is better than that of drilling cuttings. The particle size has a negative correlation with the wettability effect. The more obvious the modification effect of positive wetting agent is, the worse the modification effect of negative wetting agent is. The modification of surfactant has nothing to do with the particle size of the coal fines, but is closely related to organic components and minerals. The larger the coal particle size, the higher the settling rate, and the higher the ash content and the lower the fixed carbon content, the faster the settling rate. With the dividing point 150 mesh, the settling rate of large particles is mainly affected by particle size, while that of small particles is affected by the composition.

A gradation-dependent particle shape factor for characterizing small-strain shear modulus of sand-gravel mixtures

In this study, a series of shear wave velocity tests were conducted on two types of sand-gravel mixtures with a wide range of particle size distributions. The effect of the particle shape on the small-strain shear modulus (Gmax) was investigated using a customized, large-scale triaxial apparatus. The results showed that Gmax increases with the decrease in particle roundness when the uniformity coefficient (Cu) is less than a certain value. However, this increasing trend gradually flattens with the further increase of Cu. Thus, the effect of particle shape on the Gmax varies with the particle gradation. The performances of six relationships proposed in the literature for predicting Gmax were compared and evaluated in terms of their predictive capabilities. An empirical Gmax model based on the Hardin and Black equation was proposed by including a Fourier-based shape factor modified by Cu. The model can characterize the difference in the variation of Gmax with Cu due to different particle shapes and was thereafter validated. Furthermore, the model serves as a reference guide for estimating the Gmax of soils with various particle size distributions through their particle characteristics.

Comprehensive microstructural characterization of saline–alkali soils in the Yellow River Delta, China

ABSTRACT Soil salinization in the Yellow River Delta, China, is a matter of concern from agricultural and environmental perspectives. This study characterizes the relationship between the permeability and microstructure of saline–alkali soil. Soil microstructure, including mineral composition, pore distribution, and particle morphology of soils at different depths, was analyzed using X-ray diffraction, mercury intrusion porosimetry, and scanning electron microscopy. Results indicated that the soil mean saturated hydraulic conductivity and porosity, excluding the surface soil, were only 6.0 × 10−5 cm/s and 33.0%, respectively, and the mean proportion of clay minerals (illite, chlorite and kaolinite) was 6.1%. The pore distribution results showed that small pores (2 ≤ d< 10 μm) and micropores (0.1 ≤ d< 2 μm) constituted the majority of the soil pores. We attributed the deterioration of the soil permeability to low soil porosity, which, in turn, was associated with soil pore size distribution and a closely inlaid ‘brick wall’-type particle arrangement. Quantitative analysis of the scanning electron microscopy images showed that the fractal dimension of pores and roundness of particles increased with depth, whereas the fractal dimension of particles and roundness of pores decreased with depth. However, the azimuth, perimeter, Fred diameter, and orientation of saline–alkali soil did not significantly change with the increase in depth. This study revealed that the microstructure of saline–alkali soil exhibits a good correlation with its permeability.

Shear behaviours of cohesionless mixed soils using the DEM: The influence of coarse particle shape

The coarse particles in mixed soils can be cobbles or gravels, with the main difference being their roundness (an indicator describing particle shape characteristics at an intermediate scale). The influence of coarse particle shape (i.e., roundness) on the macroscopic and microscopic shear behaviours of cohesionless mixed soils with various fines contents (FCs) was investigated via the discrete element method in this study. The shapes of coarse particles were formed using the rotation-invariant spherical harmonic method proposed by previous investigators. An equation was proposed to predict the initial void ratios of samples in this study. A decrease in the roundness of coarse particles can increase the peak friction angle (FC≤40%) and critical friction angle (FC≤30%). As the roundness of coarse particles decreases, the peak dilatancy angle initially increases and then decreases (FC≤20%). Furthermore, it was found that the roundness of coarse particles hardly affects the classification of cohesionless mixed soils, as determined by probing the percentage contributions of coarse–coarse, coarse–fine, and fine–fine contacts. When cohesionless mixed soils change from an underfilled structure to an interactive-underfilled structure at the critical state, the main forms of coarse–coarse contacts were discovered. Additionally, the force-fabric anisotropy mechanisms of the influences of the roundness and rolling resistance coefficient of coarse particles on the shear strengths of cohesionless mixed soils were found to be different.

Microstructural properties and compressive strength of lime or/and cement solidified silt: a multi-scale study

Because of its poor engineering properties, silt often needs to be treated to meet the design requirements. Solidification using binder is one of the most common methods to improve the engineering properties of silt. Lime or/and cement are often used to treat silt. However, the mechanical properties of soil are closely related to its microstructure. Although much research has been done on the mechanical properties and stabilization mechanism of lime or/and cement solidified silt, the multi-scale research between the microstructure and macroscopic mechanics properties of solidified silt has received no attention. Therefore, in this paper, unconfined compression, mercury intrusion, and scanning electron microscope (SEM) tests were conducted on lime, cement, and lime and cement mixtures (LC) solidified silt. The microstructure parameters of particle, pore, and contact zone were extracted from SEM images. Meanwhile, the effect of curing time and binder dosage on the microstructure parameters was analyzed. In addition, the relationship between micro-parameters and macro-mechanical strength was established. The results showed that the particle diameter, particle area, contact zone diameter, and contact zone area increased with increasing curing time and binder dosage, while the pore ratio, fractal dimension of particle size distribution (PSD), and fractal dimension of contact zone size distribution (CZSD) decreased with increasing binder dosage. The unconfined compressive strength (UCS) decreased with the increase of particle roundness, pore area, pore diameter, pore ratio, and fractal dimension of PSD, and increased with increasing fractal dimension of pore size distribution (PPSD). In addition, there were no obvious relationships between UCS and pore roundness, contact zone area, and fractal dimension of CZSD.

Degradation-induced evolution of particle roundness and its effect on the shear behaviour of railway ballast

Abstract Ballast degradation has a strong effect on railway track performance (including accumulative deformation, ballast resistance, and drainage). The main objective of this research is to determine the evolution of roundness during ballast degradation and investigate the mechanical properties of real ballast shape at different abrasion stages. To this end, the Los Angeles (LA) abrasion test is conducted on three groups of fresh ballast materials with different sizes (i.e., 25–30 mm, 40–50 mm, and 50–60 mm). Then, a homemade image-acquisition platform is used to extract ballast outlines from multiple projection directions. Next, the corner sharpness of the degraded ballast is quantified by particle roundness. The LA abrasion test shows that particle roundness gradually increases with increasing abrasion. Subsequently, biaxial shear tests are performed on ballasts with different roundness characteristics based on the discrete element method (DEM). The shear behaviours of degraded ballasts with different degrees of roundness are investigated through macroscopic (e.g., the shear strength and dilatancy response) to microscopic (e.g., the mean coordination number, the ratio of sliding contacts, and the mean particle contact moment) analyses. The results show that the shear strength slightly increases in the peak state, while a substantial reduction in shear strength is observed in the residual state with increasing roundness. Moreover, the microscopic analysis shows that greater roundness results in a smaller mean coordination number, as well as decreases in the ratio of sliding contacts and the mean particle contact moment.

A new method to determine specific surface area and shape coefficient of a cohesionless granular medium

The specific surface area of soil grains (SSA) influences the physical and chemical properties of soil. Despite the widespread application of the SSA, it is often determined by analytical equations or estimated using empirical relationships and visual comparisons. On the other hand, little attention has been paid, especially to three-dimensional and precise measurements. In this study, the precise SSA and shape coefficient was measured in a group of aggregate with different sizes and shapes using a novel method. Geometrical properties such as volume and surface area were measured for each particle using X-ray micro-computed tomography (µCT) images and image processing. The particle shape coefficient was obtained from the specific surface area and effective diameter. Further, the particle shapes were measured in three distinct characteristics, sphericity, roundness, and roughness. Particle's roundness was measured by Wadell’s formula in the plan outline, which did not show an agreement with the shape coefficient. Nevertheless, as the particle sphericity decreases and roughness increases, the shape coefficient is increased. Hence, the shape coefficient of grains was classified based on the sphericity and the surface roughness. The measured SSA and shape coefficient, for 12 gradations with the three different particle size distribution and four different particle shapes, indicated good agreement with predictive analytical relations for rounded and crushed grains and more dissimilarity for flaky and elongated grains. This novel method can provide the quantitative/qualitative classification for non-spherical particles and also improve our understanding on the properties of granular media.

The Dependence Between Shear Strength Parameters and Microstructure of Subgrade Soil in Seasonal Permafrost Area

Permafrost and seasonal permafrost are widely distributed in China and all over the world. The failure of soil is mainly shear failure, and the strength of soil mainly refers to the shear strength. The two most important parameters of shear strength are cohesion and angle of internal friction. In order to ensure the sustainability of road construction in seasonal permafrost area, the microstructure of subgrade soil was observed and analyzed. First, three subgrade soils with different plasticity indices were prepared for triaxial test and scanning electron microscope (SEM). Then, these specimens underwent freezing–thawing (FT) cycles and were obtained shear strength parameters by triaxial shear test. Next, the microstructure images of soil were obtained by SEM, and the microstructure parameters of soil were extracted by image processing software. Finally, the correlation method was used to analyze the dependence between the shear strength parameters and the microstructure parameters. Results revealed that subgrade soils with a higher plasticity index had higher cohesion and lower angle of internal friction. In addition, with the increase of the number of FT cycles, the diameter and number of soil particles and pores tend to increase, while the roundness, fractal dimension and directional probabilistic entropy of particles decreased. With the increase of the plasticity index, the particle and pore diameter decreased, but the particle and pore number increased. Besides, particle roundness had the greatest influence on the cohesion and angle of internal friction of shear strength parameters.

Preparation of yttria-stabilized ZrO2 nanofiltration membrane by reverse micelles-mediated sol-gel process and its application in pesticide wastewater treatment

8 mol% yttria-stabilized ZrO2 (8YSZ) nanofiltration (NF) membranes were prepared from size-controlled spherical ZrO2 nanoparticles with an average diameter of ˜10 nm and a particle roundness value greater than 0.90, and the nanoparticles were efficiently fabricated by a reverse micelles (RMs)-mediated sol-gel process. It was found that yttria doping not only suppressed the tetragonal to monoclinic (t-m) phase transition, ensuring the membranes integrity, but also decreased the tetragonal grain size, increased the specific surface area, narrowed the pore size distribution and thus optimized the NF performance. The as-prepared 8YSZ NF membranes with a thickness of ˜260 nm exhibited high NF performances, while the pure water permeability and molecular weight cut-off (MWCO) were 3.9-4.2 L m−2 h-1 bar-1 and 800 ± 50 Da respectively. In the treatment of pesticide wastewater, the removal rate of carbofuran by 8YSZ NF membranes was more than 82%, while the maximum removal rate could reach 89%. Furthermore, the contaminated membranes could be restored as ever after alkali wash and low-temperature calcination, implementing multiple reuses.

The first day of the Cenozoic

Highly expanded Cretaceous-Paleogene (K-Pg) boundary section from the Chicxulub peak ring, recovered by International Ocean Discovery Program (IODP)-International Continental Scientific Drilling Program (ICDP) Expedition 364, provides an unprecedented window into the immediate aftermath of the impact. Site M0077 includes ∼130 m of impact melt rock and suevite deposited the first day of the Cenozoic covered by <1 m of micrite-rich carbonate deposited over subsequent weeks to years. We present an interpreted series of events based on analyses of these drill cores. Within minutes of the impact, centrally uplifted basement rock collapsed outward to form a peak ring capped in melt rock. Within tens of minutes, the peak ring was covered in ∼40 m of brecciated impact melt rock and coarse-grained suevite, including clasts possibly generated by melt-water interactions during ocean resurge. Within an hour, resurge crested the peak ring, depositing a 10-m-thick layer of suevite with increased particle roundness and sorting. Within hours, the full resurge deposit formed through settling and seiches, resulting in an 80-m-thick fining-upward, sorted suevite in the flooded crater. Within a day, the reflected rim-wave tsunami reached the crater, depositing a cross-bedded sand-to-fine gravel layer enriched in polycyclic aromatic hydrocarbons overlain by charcoal fragments. Generation of a deep crater open to the ocean allowed rapid flooding and sediment accumulation rates among the highest known in the geologic record. The high-resolution section provides insight into the impact environmental effects, including charcoal as evidence for impact-induced wildfires and a paucity of sulfur-rich evaporites from the target supporting rapid global cooling and darkness as extinction mechanisms.

Impact of three-dimensional sphericity and roundness on heat transfer in granular materials

Knowledge of particle morphology is vital to understand the behaviour of natural geomaterials including heat transfer. The effects of particle shape on heat transfer have been mostly quantified with two-dimensional (2D) particle descriptors or at most with a single three-dimensional (3D) descriptor. However, these particle shape descriptors may fail to capture the shape of all irregular particles. To redress this issue, we developed a method to reconstruct particles from micro-computed tomographic (μCT) images and to extract 3D sphericity and roundness of individual particles in the assembly. Sphericity and roundness of five real sand packings are calculated using the new proposed method. Furthermore, the effective thermal conductivity (ETC) of each sample is estimated using finite element modelling. Our results show that packings with higher sphericity or roundness tend to render higher ETC. A further examination of the microstructure in the assemblies indicates that sphericity or roundness corresponds to inter-particle contacts.

Palaeo-tsunami inundation distances deduced from roundness of gravel particles in tsunami deposits

Information on palaeo-tsunami magnitude is scientifically and socially essential to mitigate tsunami risk. However, estimating palaeo-tsunami parameters (e.g., inundation distance) from sediments is not simple because tsunami deposits reflect complex transport processes. Here, we show a new approach to estimate tsunami inundation distance based on the mixture ratio of gravels from several sources in tsunami deposits. We measured the roundness of source gravels in modern beach and fluvial deposits in a coastal valley in Japan through image analysis and then calculated the mixture ratio of both sediment types in tsunami deposits. Normalising the mixture ratios by inundation distances revealed an abrupt change in the mixture ratio at a constant percentile, regardless of tsunami magnitude. This relation allowed estimation of the inundation distance of palaeo-tsunamis during the last 4000 years.

Evaluation of fine aggregates from the Budhi Gandaki-Narayani River, central Nepal for mortar and concrete

Huge amounts of construction materials are required to fulfill construction works, which are being undertaken by local and Government levels. In this regard, searching for good quality construction materials is a tough job. The Budhi Gandaki-Narayani River is rich in carrying natural fine aggregates from the Higher and the Lesser Himalayas, which are extensively exposed along its bank. Currently ongoing and future hydro power projects, will require a tremendous amount of fine aggregates. In light of this, the present study was made to evaluate fine aggregates of the Budhi Gandaki-Narayani River. The gradation curves of fine aggregates from this river varied from well graded to uniform graded. Compositional analysis shows that quartz is dominant over other minerals. Rock fragments are composed of gneiss, schist, quartzite, metasandstone, phyllite, shale, granite, etc. Deleterious materials excluding organic matter range from 0.3 % to 1.5 % and organic matter present in range from 0.57 % to 1.11 %. The trend of presence of inorganic deleterious material and organic matter is increasing towards southern segments of the river, but they remain below 2%. Mean roundness of particles ranges from 1.88 to 2.54. Bulk dry density of fine aggregate is below 2 gm/cm³. Similarly, the specific gravity ranges between 1.49 and 1.79. Fineness modulus ranges between 1.36 and 3.50 showing that, coarse, medium, fine and very fine sediments are distributed along the stretch of river. Water absorption value of fine aggregate ranges from 0.48 % to 2.87 %. When using fine aggregates from southern segments of the Budhi Gandaki-Narayani River, reduction of mica and beneficiation process will enhance and provide better result for smooth plastering, rendering and screeding.

Effect of morphological parameters of natural sand on mechanical properties of engineered cementitious composites

Engineered Cementitious Composite (ECC) is an advanced construction material exhibiting tensile strain-hardening and multiple-cracking behavior. The tensile performance of ECC is known to be sensitive to the amount and size of sand used. Most studies on ECC have been performed with fine silica sand, while limited studies used coarser sand. However, the influence of morphological parameters of sand on the mechanical performance of ECC has not yet been explored, which is the focus of the present study. The morphological parameters (including particle roundness and sphericity) of sand were objectively determined using image analysis and computer algorithms, while the ECC compressive and tensile properties were experimentally measured. It was concluded that decreasing sand particle roundness and sphericity led to enhancements in compressive strength, ultimate tensile strength and tensile strain capacity of ECC. Gabbro sand, with the lowest roundness and sphericity among the four natural sand types studied, resulted in the best ECC mechanical properties. This natural sand can serve as an effective alternative to the typical manufactured fine silica sand used in ECC with reduced material cost and environmental impact. The findings of this study support the broader utilization of local natural sand in ECC in practical applications.

The combined effects of Sr additions and heat treatment on the microstructure and mechanical properties of high pressure die cast A383 alloy

The microstructures and mechanical properties of high pressure die cast A383 alloys under four conditions (with and without Sr additions and heat treatment) were investigated. Sr addition is responsible for the increase in the elongation of high pressure die cast A383 alloys by refining the eutectic Si particles from long, needle-like morphologies to fine, fibrous ones. High cooling rates, as generated in the high pressure die casting process, also significantly contribute to the microstructural refinement of the eutectic Si particles. However, there was almost no relationship between the morphologies (size and roundness) of the eutectic Si particles and the yield strength of high pressure die cast A383 alloys. Heat treatment (aging without solution treatment) increased the yield strength of high pressure die cast A383 alloys. Sr addition combined with heat treatment was found to refine the size of aging precipitates and therefore improve the yield strength beyond the levels observed for heat treatment alone. The sludge characteristics (size, roundness and fraction) were not affected by the different heat treatments and Sr additions and had no discernible effect on the change in mechanical properties.