Dry Particles Research Articles

Optimalizace přípravy sprejově sušených porézních mikročástic pro podání do plic

Inhalation administration of dry powder particles is a common application route to achieve local and systemic drug effects. For pulmonary diseases, the deposition of drugs at the site of action is desirable. Thus, the parameters of the inhaled particles,

Comparison of four digestion protocols on the physical characteristics of gastric digesta from cooked couscous using the Human Gastric Simulator.

In vitro digestion is widely employed in food, nutraceutical and pharmaceutical research, and numerous in vitro gastric digestion protocols have been proposed, with a wide range of experimental conditions. Differences in the simulated gastric fluids (pH, mineral content, enzyme type and enzyme activity) of different digestion protocols may alter the results for the digestion of the same meal. This study aimed to investigate how variations in the gastric secretion rate and composition in four in vitro digestion protocols (Infogest Riddet, Infogest Semi-dynamic, UC Davis and United States Pharmacopeia) impacted the physical properties of the emptied gastric digesta. Cooked couscous was used as a model meal and subjected to simulated gastric digestion using a dynamic gastric model, the Human Gastric Simulator (HGS). The digesta were collected from the outlet of the HGS after 15, 30, 60, 90, 120, 150, or 180 min. The gastric emptying of dry matter, pH, rheological properties, and particle size were evaluated. The digestion protocol significantly influenced the solid content and moisture content of the digesta (p < 0.001), particles per gram of dry matter (p < 0.0001), gastric emptying of dry matter (p < 0.003), shear stress at 0.45 s-1 and consistency coefficient (p < 0.0001). The presence of NaHCO3 in the Infogest Riddet and Infogest Semi-dynamic gastric secretions provided an additional buffering effect and increased the digesta pH during gastric digestion. Similarly, the inclusion of mucin in the UC Davis protocol resulted in a higher flow and viscoelastic properties of the emptied digesta. The highest dilution of gastric content in the United States Pharmacopeia (USP) protocol resulted in larger particles emptied from the HGS and the longest gastric emptying half-time of all digestion protocols. These findings provide new insights into the impact of digestion protocols on the digesta properties, which can be beneficial for the design and standardization of in vitro digestion models.

Development of a mathematical model of the process of mixing liquid feed in an experimental setup and optimization of design parameters

The role of agricultural ecology in current conditions is important in the modern world, as it offers new methods and approaches to the implementation of production processes that should reduce the harmful effects on the environment. The paper outlines the prerequisites for the development of universal mechanization tools for the process of mixing dry and liquid components. The essence of the method is to study the motion of a particle with different design parameters, as well as the physical properties of the medium. The mathematical model of particle motion is built on the basis of theoretical mechanics and hydraulics. The calculation scheme of the impeller is performed from several iterations with a step-by-step approach to the simulated mixing process. In this case, differential equations of motion of dry material particles are applied. Based on the solutions of these equations, the particle motion zone within the impeller structure is determined. At the next stage, the calculation of velocities at different angular speeds and viscosity of the liquid medium is carried out. Thus, there is a consistent approach to the description of the process of mixing a particle with a liquid. According to the proposed algorithm, a program has been developed using MathCad V15 that provides the possibility of graphical and numerical control of the calculation results with a change in parameters. It is possible to change the structural and physical parameters of the environment. Examples of calculation and graphical interpretation of particle motion in the working chamber are presented. According to their results, the optimal modes of operation of the setup for the preparation of liquid feed are proposed.

Evaporation Affects the In Vitro Deposition of Nebulized Droplet in an Idealized Mouth-Throat Model

Nebulizer is one of inhalation therapy’s most widely used aerosol generation devices. Nowadays, the vibrating mesh nebulizer has become popular owing to its compactness and noiselessness. In this study, an experimental system is proposed to measure the deposition fraction (DF) of nebulized sodium chloride (NaCl) droplets in an idealized mouth-throat airway model. The results show that before the DF increases to 58.6% with an increasing flow rate to 60 L/min, there is a decrease in DF from 42.4% to 15.5% when the inhalation flow rate increases from 15 to 22.5 L/min for a normal saline solution. These results substantially differ from the conclusions of dry powder or particle experiments and simulations, which monotonously increases with increasing inhalation flow rate. This suggests that droplet evaporation during aerosol generation and transport in the airway plays an important role. The experiment also showed that droplets generated from solutions with a higher NaCl concentration have higher DFs.

Dissolution and Absorption of Inhaled Drug Particles in the Lungs.

Dry powder inhalation therapy has been effective in treating localized lung diseases such asthma, chronic obstructive pulmonary diseases (COPD), cystic fibrosis and lung infections. In vitro characterization of dry powder formulations includes the determination of physicochemical nature and aerosol performance of powder particles. The relationship between particle properties (size, shape, surface morphology, porosity, solid state nature, and surface hydrophobicity) and aerosol performance of an inhalable dry powder formulation has been well established. However, unlike oral formulations, there is no standard dissolution method for evaluating the dissolution behavior of the inhalable dry powder particles in the lungs. This review focuses on various dissolution systems and absorption models, which have been developed to evaluate dry powder formulations. It covers a summary of airway epithelium, hurdles to developing an in vitro dissolution method for the inhaled dry powder particles, fine particle dose collection methods, various in vitro dissolution testing methods developed for dry powder particles, and models commonly used to study absorption of inhaled drug.

COVID-19 바이러스의 확산에 대한 에어컨 기류의 영향 분석

This study analyzed the transmission mechanism of viruses according to operating conditions of air conditioners in small restaurants using CFD based on the actual occurrence situation. COVID-19 virus (SARS-CoV-2) is known to be spread through droplets. However, in a closed environment, after some period of time, droplets become dry and fine particles (aerosols) that can be transmitted in air. The spread of virus-laden aerosols with or without air-conditioner operation was analyzed by three-dimensional CFD simulation taking into account the heating effect of human body and thermal effect of an indoor heat source (e.g., food in a heated pot). Results showed that air currents of air-conditioners diffused virus-laden aerosols indoors and the return airflow of air-conditioner re-diffused the contaminated air throughout the room. Especially, when the airflow hit a structure, it created a vortex and built up high concentrations of pollutants due to accumulation. On the other hand, pollutant concentrations were low around areas of fresh air inflow (infiltration). These results imply the importance of ventilation.

Throttle and expansion characteristics of supercritical carbon dioxide during its venting

Supercritical CO2 has important applications in the fields of power cycle generation systems and carbon capture, utilization and storage (CCUS). The venting equipment represents a fundamental pressure-relief method for the purpose of depressurizing sections of those systems for inspection, maintenance or repair. The extremely low temperatures, dry ice blockage and overpressurization will appear in the system due to the throttling and expansion effect during venting. Meanwhile, the released CO2 may cause the exposure for the high density gaseous CO2, solid CO2 particles and cryogenics to the people in the venting area. The study of flow characteristics during CO2 venting is absolutely essential for assessing the hazard probability of dry ice formation and the blockage of relief valves during emergency or routine operational venting. In this paper, the theoretical analysis and experimental tests were conducted to study the throttle and expansion characteristics through the elbow, valve and orifice during straight vertical venting of supercritical CO2 with a 258 m long, 233 mm inner diameter pipeline system. The pressures and temperatures inside the main pipe and vent pipe, and the temperatures near field region were recorded during venting. After the valve was opened, the pressure in the vent pipe rose rapidly, and the rising range decreased with the decrease of the distance from the orifice. The temperature drops of CO2 were obvious after supercritical CO2 passed through the bend, the valve and the orifice. The supercritical CO2 in the main pipe changed into gas-liquid two-phase, and the liquid CO2 were produced in the vent pipe due to the throttling expansion effect. The CO2 temperature near the orifice were in quasi steady state after reaching the lowest value due to the continuous vaporization of liquid-phase CO2 and sublimation of dry ice particles, accompanied by the air entrainment process.

Dry Syrup: A Comprehensive Review

The oral dosage forms are most popular because of their ease of administration, patient compliance, and formulation stability. Tablets and capsules, the most popular oral dosage form, have the drawback of difficulty swallowing the dosage form specially developed for pediatric and geriatric patients. In recent times the, modern scientific and technological advancement in pharmaceutical field has created a bank of interest in the reconstitutable oral suspension (Dry syrup). Dry syrups are the dry mixtures that require adding water at the dispensing time. Dry syrups show adequate chemical stability of drug during shelf life and reduce the final product's weight. Moreover, dry syrups show higher bioavailability than tablets and capsules as they disintegrate in water outside the oral cavity and directly enter the gastrointestinal tract. Most of the drugs prepared as dry powders for oral suspensions are antibiotics. The present review gives an account of the excipients used, methods of preparation of dry syrup, their evaluation, and their packaging. When manufacturing dry syrup medicine, the dry mixture should have a uniform concentration of the required ingredients. This ensures that the drug does not break up into a non-homogeneous mixture when reconstituted, which may lead to errors in dosage. The items used in the manufacturing of dry syrup include excipients, granule disintegrating, granule binder and powder blends. Excipients are used to stabilize active ingredients for a long period. The type of excipient used is based on the suitability for reconstitution and the type of the powder the granule disintegrate helps ensure the dry syrup particles do not aggregate during reconstitution. The granule binder helps ensure that the dry syrup's particles settle in the suspension.

Hard ultralight systems by thermal spray deposition of WC-CoCr onto AZ31 magnesium alloy

Magnesium alloys in general, and AZ31 in particular, have huge potential as materials for energy saving and emissions reduction in the transportation of people and goods, because of their low density (about 1.7 g∙cm−3) coupled to good bulk mechanical properties. The main weakness is represented by the alloy surface, prone to corrosion and rather soft. Coatings are therefore mandatory, especially in harsh environments. To obtain AZ31 materials with exceptional surface properties High Velocity Oxygen-Fuel (HVOF) thermal spray was exploited to deposit a WC-CoCr coating with very high surface hardness. Because of the heat sensitivity of magnesium alloys, the influence of torch-substrate kinematics and substrate surface preparation on the surface temperature during deposition, the metallurgical characteristics of AZ31, and the residual stress state of the coated samples were investigated. The overall quality of the coatings was also evaluated by abrasion and electrochemical corrosion resistance tests. Proper adjustment of the torch/substrate standoff distance and torch patterning strategy reduced the surface temperature during deposition by around 100 °C, as measured with an IR pyrometer. This also resulted in a decreased magnitude of the average compressive stress in the coating. At the same time, these adjustments did not impair measurably the performances of the coatings, which, regardless of the deposition conditions, had approximately 1200 HV0.3 hardness, 2–4 μA∙cm−2 corrosion current density in 3.5 wt./vol% NaCl aqueous solution, and 7–8 × 10−4 mm3∙(N∙m)−1 specific wear rate under dry particles' abrasion conditions. Cyclic impact tests also showed that the coatings adhered equally well to grit-blasted or machined surfaces. On the other hand, transverse cracks developed across the coatings during impact tests because of the much higher elastic and plastic deformability of the AZ31 substrate. The avoidance of grit-blasting and the lowered deposition temperatures were also important to prevent anomalous grain growth in the AZ31 substrate.

ABF de-hazing algorithm based on deep learning CNN for single I-Haze detection

Haze is a kind of natural event which is formed by smoke, dust, or other dry particles. It acts as an overshot-on scene and degrades the visibility of environments and damages the image quality of indoor pictures due to the haze changing colors. Therefore, the importance of removing the haze from the images is increased in the field of computer graphics or vision. Because of its obscurity in mathematical formation, the removal process of haze becomes very complex and it is also made more difficult when the image is in a form of a purely single image. Here, the single-image haze removal process is the most complicated operation because of its ill-posed behavior. In this paper, the authors proposed a powerful single-image haze removal and recognition process. An Adaptive Bilateral Filter (ABF) is designed using an optimal selection of spatial weight parameters for de-hazing the scene depth of the hazy image. It is essential to classify both the haze and non-haze images because, without performing detection tasks, the non-haze images are also fed into the de-hazing process and lead to system complexity. Henceforth for detection purposes, a deep Convolution Neural Network is proposed to categorize the haze and non-haze images. Here deep CNN is proposed for recovering the depth information in an input image using a network training and testing model. The simulation results are demonstrating that the presented technique performed very well in the identification of the de-hazing effect and efficiency of haze removal algorithms.

Optical properties of marine aerosol: modelling the transition from dry, irregularly shaped crystals to brine-coated, dissolving salt particles

An aerosol-optics model for water-coated marine aerosols is introduced that accounts for irregularities in the geometry of dry salt particles, and that mimics the processes of water-adsorption, dissolution of salt, and rearrangement of the liquid mantle following dissolution. The model can be tuned to adjust how rapidly the dry salt particles become spherical as water is being added to them. Size-shape distributions of the model are generated and employed to compute the ensemble-averaged extinction and backscattering cross sections, the lidar ratio, and the linear backscatter depolarisation ratio (LDR). A power law distribution that is frequently used in chemical transport models yields lidar ratios and LDR values that are consistent with field and satellite observations. But the results are found to be quite sensitive to the assumed size distribution. A generic lognormal size distribution tends to produce higher extinction cross sections, backscattering cross sections, and somewhat higher lidar ratios than the power-law distribution, while the depolarisation ratios are of comparable magnitude. We further gauged the model’s performance by comparing it with homogeneous superellipsoids. For a salt mass fraction of 0.97, the cross sections and the lidar ratio of cubic superellipsoids (i.e., those with unit aspect ratios) agree best with the reference model over all effective radii at a superellipsoid roundness parameter of 0.6. The LDR is more challenging to reproduce. For a salt mass fraction of 0.97, cubic homogeneous superellipsoids mostly give lower LDR values than the reference model. However, by increasing one aspect ratio, the superellipsoids can be tuned to yield higher LDR values. For a salt mass fraction of 0.91, the reference model yields LDR values below 0.1. Homogeneous superellipsoids that match the cross sections and lidar ratio of the reference model tend to give LDR values exceeding the reference results, at least for super-micron particles.

Evolution of mesoscale structure in fluidized beds with non-spherical dry and wet particles

Instantaneous force distributions at bubble boundaries in non-spherical dry and wet particle systems. • The force distributions at bubble boundaries are analyzed to explain the influence mechanism of different shapes of bubbles in non-spherical dry and wet particle systems. • The effects of particle aspect ratio and liquid viscosities are investigated through the force analysis and factorial analysis. • With the increase of the particle aspect ratio, the bubble equivalent diameter gradually increases. • As the liquid viscosity increases, the bubble frequency gradually decreases. Fluidized beds with non-spherical dry and wet particles are widely used in industrial processes, and the mesoscale structure in the bed has an important influence. In this study, CFD-DEM simulations are performed to evaluate the flow behaviors and mesoscale structure in fluidized beds with non-spherical dry and wet particles. The accuracy of the model is validated by comparison with the results of the particle image velocimetry experiment. The force distributions at bubble boundaries are analyzed to explain the influence mechanism of different shapes of bubbles in non-spherical dry and wet particle systems. The factor analysis indicates the interaction of particle shape and viscous liquid on the translational and rotational kinetic energy of particles. When the bed height is low, as the particle aspect ratio increases, the bubble equivalent diameter gradually increases. In addition, as the liquid viscosity increases, the particle and bubble granular temperature gradually decrease, indicating the reduction of particle velocity fluctuate and the decrease of turbulent kinetic energy of bubble. These findings have guiding significance for the fluidization of non-spherical dry and wet particles and can be used to optimize related industrial processes.

Radar Retrieval Evaluation and Investigation of Dendritic Growth Layer Polarimetric Signatures in a Winter Storm

Abstract This study evaluates ice particle size distribution and aspect ratio φ Multi-Radar Multi-Sensor (MRMS) dual-polarization radar retrievals through a direct comparison with two legs of observational aircraft data obtained during a winter storm case from the Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) campaign. In situ cloud probes, satellite, and MRMS observations illustrate that the often-observed Kdp and ZDR enhancement regions in the dendritic growth layer can either indicate a local number concentration increase of dry ice particles or the presence of ice particles mixed with a significant number of supercooled liquid droplets. Relative to in situ measurements, MRMS retrievals on average underestimated mean volume diameters by 50% and overestimated number concentrations by over 100%. IWC retrievals using ZDR and Kdp within the dendritic growth layer were minimally biased relative to in situ calculations where retrievals yielded −2% median relative error for the entire aircraft leg. Incorporating φ retrievals decreased both the magnitude and spread of polarimetric retrievals below the dendritic growth layer. While φ radar retrievals suggest that observed dendritic growth layer particles were nonspherical (0.1 ≤ φ ≤ 0.2), in situ projected aspect ratios, idealized numerical simulations, and habit classifications from cloud probe images suggest that the population mean φ was generally much higher. Coordinated aircraft radar reflectivity with in situ observations suggests that the MRMS systematically underestimated reflectivity and could not resolve local peaks in mean volume diameter sizes. These results highlight the need to consider particle assumptions and radar limitations when performing retrievals. significance statement Developing snow is often detectable using weather radars. Meteorologists combine these radar measurements with mathematical equations to study how snow forms in order to determine how much snow will fall. This study evaluates current methods for estimating the total number and mass, sizes, and shapes of snowflakes from radar using images of individual snowflakes taken during two aircraft legs. Radar estimates of snowflake properties were most consistent with aircraft data inside regions with prominent radar signatures. However, radar estimates of snowflake shapes were not consistent with observed shapes estimated from the snowflake images. Although additional research is needed, these results bolster understanding of snow-growth physics and uncertainties between radar measurements and snow production that can improve future snowfall forecasting.

A concise treatise on model-based enhancements of cohesive powder properties via dry particle coating

• Advances in model-guided dry coating of cohesive powder flow enhancement presented. • Chen-NJCEP model explains the mechanism of dry coating induced flow enhancements. • Models offered for the guest amount and type, and granular Bond number estimation. • Dry coating led to drastically enhance flow, packing, agglomeration, dissolution. • Agglomeration, indicator of flowability, dramatically reduced with dry coating. This paper presents a review of our key advances in model-guided dry coating-based enhancements of poor flow and packing of fine cohesive powders. The existing van der Waals force-based particle-contact models are reviewed to elucidate the main mechanism of flow enhancement through silica dry coating. Our multi-asperity model explains the effect of the amount of silica, insufficient flowability enhancements through conventional blending, and the predominant effect of particle surface roughness on cohesion reduction. Models are presented for the determination of the amount and type of guest particles, and estimation of the granular Bond number, used for cohesion nondimensionalization, based on particle size, particle density, asperity size, surface area coverage, and dispersive surface energy. Selection of the processing conditions for LabRAM, a benchmarking device, is presented followed by key examples of enhancements of flow, packing, agglomeration, and dissolution through the dry coating. Powder agglomeration is shown as a screening indicator of powder flowability. The mixing synergy is identified as a cause for enhanced blend flowability with a minor dry coated constituent at silica < 0.01%. The analysis and outcomes presented in this paper are intended to demonstrate the importance of dry coating as an essential tool for industry practitioners.

Energy Saving on Spray Drying Process by Modifying the Hot Air Flow

The drying machine works with the Spray Dryer method to dry particles from a liquid state through continuous spraying in the drying chamber. This Spray Dryer uses an atomizer in the form of a 0.2mm mist nozzle type injector with a spraying capacity of 0.00045 kg/s. Function for atomization during the drying process occurs with a change in the vortex angle of 35°. In this study, the liquid used was pure cow’s milk with a specific heat value of 3930 J/kg K. To increase the total amount of solids, increase the volume, speed up the drying process, and prevent material damage due to high temperatures, the milk was mixed with maltodextrin, water, and salt. In this drying process, the temperatures used are 100°C, 105°C, and 110°C. The humidity of the surrounding air can be reduced by using a dehumidifier containing a zeolite stone type molecular sieve measuring 1.7-2.5mm as an absorbent. The results of this study indicate that the moisture content of dry powdered milk products is 10.01% using a temperature of 105°C with a drying air flow speed of 16 m/sec. In addition, the drying time process was taken a time of 73 minutes which resulted in a drying rate of 0.455gram/second. This dehumidifier affects the temperature in the drying chamber to be constant between 101°C-104°C and lowers the humidity of the air by 7%, resulting in a 222gram milk soak. The efficiency value of the drying machine with a temperature of 105°C is 18.68%.

COMPARATIVE STUDY OF PARTICLEBOARDS WITH HEVEA BRASILIENSIS WASTE FROM DIFFERENT PRODUCTION AND MOISTURE CONFIGURATIONS

After the production cycle of latex, Hevea brasiliensistrees becomeresidual living plants for this activity, although their woody trunks are still potentially subject to industrial utilization. Bio-composites derived from rubberwood particles were manufactured using two different configurations as a strategy to examine the potential of this species with respect to mechanical behavior. Homogeneous panels were developed from particles at the saturation condition, and heterogeneous panels were obtained from dry particles conditioned at 12% moisture content. Both examples were heat-pressed and glued with castor oil-based polyurethane resin. Density, short-term water absorption and thickness swelling, modulus of rupture and modulus of elasticity in the static bending and perpendicular tensile were evaluated. Panels derived fromrubberwood particles proved to be viable according to the technical standards.

A Review of Dispersion Film Drying Research

Abstract Dispersion drying is an essential step in an enormous number of research and industry fields, including self-assembly, membrane fabrication, printing, battery electrode fabrication, painting, and large-scale solar cell fabrication. The drying process of dispersion directly influences the structure and properties of the resulting dried film. Thus, it is important to investigate the underlying physics of dispersion drying and the effects of different drying parameters. This article reviews modeling studies of coating drying processes, along with corresponding experimental observations. We have divided drying processes into two conceptual stages. In the first drying stage, liquid evaporation, particle sedimentation, and Brownian motion compete and affect the particle distribution during drying and thus in the final film structure. We have included a comprehensive discussion of the influences of drying parameters, such as evaporation rate, particle sizes, and temperature, on the above competition and the resulting film structure. A drying regime map describing where different drying phenomena dominate was formulated based on the literature. We also extended our discussion to the practical applications of battery slurry drying an essential step in conventional battery electrode manufacturing. In the second drying stage, the physics of porous drying and crack formation are reviewed. This review aims to provide a comprehensive understanding of dispersion drying mechanisms and to provide guidance in the design of film products with favorable structures and properties for targeted practical applications.

Sediment trap height affects mass, particle size, and biogeochemical composition of material collected in an equatorial coral reef.

Anthropogenic sedimentation is a major contributor to the worldwide decline in coral cover. Resuspension of benthic material can exacerbate the threat to corals, but evidence of vertical sediment gradients is limited. Here, we installed sediment traps at 10, 20, 30, 40, and 50cm above the substrate at three equatorial reef sites for three months and determined the dry mass, particle size, and biogeochemical composition of the material collected. As the trap mouth height increased from 10 to 50cm, dry mass decreased as sediments became finer, poorer in carbonate, and richer in silicate. Despite among-site differences in collected sediment, this vertical gradient was present in all trap arrays, likely driven by resuspension mechanisms on seabed sediments. These results have implications for coral vertical ecology and underline the importance of standardising sediment collection protocols.

Influence of Thermal Treatment of Moroccan Red Clay on its Physicochemical and Mechanical Behavior

AbstractRed clay is considered to be of significant value to the economy in Morocco, particularly in the Safi region, because of its abundance. This raw material has long been known for its quality in the manufacture of clay materials, but its use was limited to traditional ceramics. The red clay raw material was the subject of the current study with the objective of opening new industrial applications that will give added value to the Safi red clay. The physicochemical, mineralogical, and thermal properties of the Moroccan red clay were determined by X-ray fluorescence (XRF), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis, X-ray diffraction (XRD), oriented aggregate, and particle-size analyses, powder density by helium pycnometry, carbonate content using the Bernard method, differential thermal analysis (TG–DTA), and the BET surface area. The compacted dry powder particles were calcined at three sintering temperatures: 900, 1000, and 1100°C for 2 h. The effect of sintering temperature on ceramic properties, such as apparent porosity, water adsorption, bulk density, and mechanical strength, was examined. Dense ceramics with lower porosity and greater mechanical resistance (~300%) were produced by increasing the sintering temperature from 900 to 1100°C. The conclusion was that the evolution of physicochemical and thermal properties is related to mineralogical changes, which show that anorthite is the major phase at higher temperatures.

Precise mix-design of Ultra-High Performance Concrete (UHPC) based on physicochemical packing method: From the perspective of cement hydration

• A physicochemical packing method to optimize the design of UHPC is proposed. • A new equivalent particle size distribution of hydrated cement is calculated. • The macro characteristics of the newly developed UHPC is evaluated. • The hydration kinetics of the newly developed UHPC is evaluated. • The microstructure development of the newly developed UHPC is evaluated. It is widely accepted that Ultra-High Performance Concrete (UHPC) could be designed by the employment of Modified Andreasen and Andersen (MAA) particle packing model. However, the traditional MAA model only takes into account that dry particles reach the dense packing status under physical conditions, without considering the chemical hydration of wet cement particles. To solve this problem, this study adopts a physicochemical packing method to optimize the mix-design of UHPC through establishing a new equivalent particle size distribution of hydrated cement by applying a multilayer spherical shell model. Based on this, the mix proportion of UHPC is redesigned and the properties of the optimized UHPC are evaluated afterwards. The results show that the optimized mix-design leads to higher particle packing density of UHPC, thereby improving the durability on the premise of guaranteeing the workability and mechanical properties. Meanwhile, the optimized mix-design can also achieve denser micro structures of UHPC matrix, which provides a valuable reference to design UHPC more scientifically and reasonably.