Particle Size Distribution Curves Research Articles

A universal gradation for highway pavement base course materials

Around the world, several standards and guidelines exist for the construction of highway pavement base courses. In the current global construction environment, an engineer may be dealing with a highway project sitting in a place far away from the construction site, and there may be an urgent need to work on a preliminary analysis and design of the pavement. In such situation, it would be advantageous to have a universal gradation of the base course materials. Therefore, this study aims to develop such a gradation, considering the standard guidelines being adopted in several countries including Australia, Brazil, various European nations, India, Iran, New Zealand, South Africa and USA. The analysis has resulted in three different particle-size distribution (PSD) ranges; however, one of the three has been proposed as the universal gradation in view of the most common or widespread practice. The gradation has been developed both in the form of a PSD curve, as well as in a tabular form. It was observed that the universal gradation consists of the largest particle size of 50 mm and permissible fines (particles smaller than 0.075 mm) content of 2–8%.

The best mathematical models describing particle size distribution of soils

Since particle size distribution (PSD) is a fundamental soil physical property, so determination of its accurate and continuous curve is important. Many models have been introduced to describe PSD curve, but their fitting capability in different textural groups have been rarely investigated. The aim of this study was to evaluate the fitting ability of 15 models on 2653 soil samples from 13 province of Iran, and to determine the best model among them for the PSD of all soil samples as well as for each soil textural group based on evaluation criteria. Results showed that the Weibull model was the most accurate model for all soil samples as well as for the clayey and loamy groups. After the Weibull, Fredlund, Rosin–Rammler and van Genuchten were the most accurate models. However, their differences were not significant (p ≤ 0.05). Also, for the coarse texture group the S-shape model showed the better fit than the others. These results showed the performance of a particular model varies with the soil textural characteristics.

Precipitation of Rare Earth Phosphates from Molten Salts: Particle Size Distribution Analysis

Phosphate precipitation is one of the possible methods for removing rare earth fission product (FP) elements from the technological melts in pyrochemical processes of spent nuclear fuel (SNF) reprocessing. Chemical and phase composition of the phosphates depends on the cationic composition of the melt and, in some instances, on the precipitant employed. Technologically attractive melts include 3LiCl–2KCl and NaCl–2CsCl eutectic mixtures and NaCl–KCl equimolar mixture. Previous studies showed that the normal rare earth orthophosphates (REEPO4) are formed in the 3LiCl–2KCl based melts. In NaCl–KCl and NaCl–2CsCl melts the composition of the precipitate is influenced by the initial phosphate-to-rare earth element molar ratio, and normal as well as double alkali metal – rare earth phosphates (M3REE(PO4)2 or M3REE2(PO4)3) can be produced. After precipitating rare earth FPs, the precipitate needs to be separated from the melt to allow the electrolyte reuse. Solid phosphates can be removed by filtering or collected employing submergible centrifuges. Particle-size distribution (PSD) of the solid precipitate can greatly affect the efficiency of the collection device. After the phosphates are separated they can be further treated for the final disposal, for example, by incorporating them into a suitable glass matrix (a vitrification process). Here again the PSD of the solid material can be important in understanding the properties of the final waste form. Despite the phosphate precipitation process has been studied by various techniques, there is very little information concerning the particle size of the precipitates formed in the process. In the present work the effect of the initial phosphate precipitant-to-rare earth mole ratio on the particle size of the rare earth phosphates was investigated. The experiments were performed in NaCl–2CsCl and NaCl–KCl based melts at 650 and 750 oC, respectively. The REEs studied included La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb, where the heavier lanthanides (which are not the fission products) were included for comparison. Phosphate precipitant was added in the amount required for 50 and 100 % precipitation of the REE. In addition, the melts containing the mixture of REEs imitating their content in a typical light water reactor SNF arriving for reprocessing were studied. Particle size of the precipitated phosphates was determined by laser diffraction method employing ANALYSETTE 22 NanoTec (Fritsch) instrument with a measuring range of 0.02–2100 μm. The measurements were performed both with and without using ultrasound to asses the effect of ultrasonic treatment on the particle deagglomeration. The obtained results showed that the particle size of the precipitated phosphates typically lies in the range of 0.1–100 μm. Fraction of the particles with the size below 1 μm is relatively small. The results of the measurements showed that the particles of the phosphates are agglomerated, maxima in the PSD curves shift towards lower values after the ultrasonic treatment of the samples. Heavier lanthanides tend to form larger particles. For example, maxima in the PSD curves of the phosphates produced at 100 % precipitation in NaCl–2CsCl melts shifted from ca. 6 μm for lanthanum to ca. 20 μm for ytterbium. The effect of the initial phosphate-to-REE molar ratio in the melt on the particle size is not straightforward. For the lighter lanthanides (from Ce to Sm) PSD curves for the precipitates obtained at 50 % degree of precipitation have two maxima – around 1 and 10–20 μm, and the average particle size is smaller than for the solids obtained at 100 % REE precipitation. For the heavier lanthanides the average size of the particles obtained at 50 % REE precipitation was greater than at complete precipitation. Cationic composition of the melt does not significantly affect the average size of the particles of REE phosphates, although influences the particle-size distribution. Examples of the results obtained for precipitation of the sum of REE from NaCl–2CsCl and NaCl–KCl based melts are shown in the Figure. Bulk of the particles has the size within 1–100 μm limits. Figure 1

Aggregation kinetics of OX50 hydrosols in NaCl solutions studied by dynamic light scattering

The aggregation kinetics of OX50 sols in aqueous NaCl solutions (10–4–2 × 10–1 M) has been studied for 15 days or more by dynamic light scattering. The following set of characteristics has been considered to quantitatively estimate the coagulation intensity in the disperse systems: the particle size corresponding to the maximum in the differential particle size distribution curve, the height of the maximum, the polydispersity index, and the average diameter of the intensity distribution. It has been found that slow sol coagulation proceeds via the barrierless mechanism in secondary potential minimum, which arises from the predominance of the dispersion attractive forces over structural and electrostatic repulsive forces.

Rules of pulverized coal output under different components of coal petrography and different coal structure in Hancheng Block, China

In order to study the output mechanism and influencing factors of pulverized coal under different components of coal petrography and different coal structures during the process of drainage, the physical simulation experiments were conducted under the state of single-phase water flow displacement. The results of this experiment for different coal petrography show the weight of pulverized coal output is normally 11# coal > 5# coal > 3# coal with different displacement velocities, and the increasing ratio of pulverized coal output is 5# coal > 11# coal with the different confining stress in the constant displacement velocity. For different coal structures the pulverized coal output weight of fragmented coal is much larger than the primary structure of coal. The particle size distribution curve shows 3#, 5# and 11# primary structure of coal have a double-peak, and the grain size of primary pulverized coal is relatively small and the secondary pulverized coal is relatively large. However, the grain size distribution of fragmented coal is a double-peak distribution, and the distribution scope is relatively concentrated and the average grain size is small. Therefore, the characteristics of pulverized coal were found to be related to its coal different coal petrography components and coal structure.

Pedogenetic interpretations of particle-size distribution curves for an alpine environment

The Qilian Mountains are generally capped by a productive silty soil layer wherever the environment allows. As Holocene loess is prevalent across the Qilian Mountains, we assume that at least some of these fine sediments are derived from loess deposition and that soils across the region may be genetically linked. To test these hypotheses, nine pedons in different landscapes within a typical alpine watershed of the Qilian Mountains were sampled. We also collected fine earth samples from glacier surfaces and crevices of glacial debris in the moraine zone. The particle-size distribution (PSD) is used as a proxy for identifying aeolian fractions in soils. The PSD curves of all of the fine-earth fractions examined are polymodal, although three modal sizes of roughly 16μm, 35μm and 80μm are found in almost all sediments in varying proportions. These modal sizes have been identified as three sources of aeolian sediments in different transport systems. The composition and thickness of loess sediments are related to local site conditions and may be related to the paleoenvironmental history of the site. Clastic debris and vegetation cover serve as dust traps during different stages of soil formation in this alpine environment, and soils grow upward with accumulating loess sediment. Our study demonstrates that PSD curves can be used to determine the origins (and especially aeolian origins) of soils. Furthermore, this study provides insight into the pedology, ecology and paleoenvironmental history of loess-affected ecosystems in alpine areas of the Qinghai-Tibetan Plateau.

Development of Animal Drawn Peg Planker for Secondary Tillage in Hill Agriculture

Indigenous wooden log with peg type harrow, locally known as dante in Sikkim, is used for secondary tillage. Several designs of improved peg type harrow for the plains are not suitable for the narrow terraces of less than 3.0 m width on steep hills. An animal drawn peg planker of 800 mm working width made of mild steel sheet was developed to suit the topographical conditions of the North Eastern Hill Region of India, and serve as a substitute to the local wooden peg type harrow. The animal drawn peg planker was field tested by determining the soil particle size distribution curve. The average post-operation large size clod was of 112.55 × 81.25 mm in control plot and 71.82 × 54.70 mm in field operated by the peg planker. The local wooden peg harrow and the developed peg planker had work rate of 0.035 and 0.047 ha.h-1; and draft requirement of 52.0 kgf and 48.0 kgf, respectively. The effective size, uniformity coefficient and coefficient of gradation were 0.17, 20.0, 0.97 and 0.25, 40.0,1.91, respectively, for the local wooden peg harrow and the developed peg planker. These values suggested that the soil was finer, well and uniformly graded by use of the developed peg planker as compared to the local wooden peg harrow. The total energy input required was 2077.96 MJ.ha-1 and 1546.97 MJ.ha-1 for local wooden peg harrow and developed peg planker, respectively. The saving in energy input by use of the developed planker was 25.55 per cent.

Effect of Composition on Basic Properties of Engineered Media for Living Roofs and Bioretention

AbstractEngineered media used in living roofs and bioretention plays a crucial role in determining stormwater mitigation performance. Engineered media with compositions varying in four aggregates, volumetric ratio of compost (0, 10, and 20%) and three amendments (zeolite, paving sand, and topsoil) were prepared in the laboratory. Media basic properties including particle-size distribution (PSD), dry bulk density, particle density, porosity, and saturated hydraulic conductivity (Ks), were characterized and investigated as a function of the varying composition. All media are classified as poorly-graded sand (SP), exhibiting porosity greater than 0.51, with magnitudes of Ks ranging from 10−2 to 10−1 cm/s. Media with pumice-based aggregates have particle densities between 2.21 and 2.48 g/cm3. The Ks of a pure aggregate classified as SP is positively related to the particle size corresponding to 50% fines on the cumulative PSD curve. Ks values of four aggregates either remain unchanged or decrease by 73% at ...

Optimal model for particle size distribution of granular soil

In this study an attempt is made to develop an optimal parametric model to represent the particle size distribution (PSD) curves of granular soils based on experimental data. Four unimodal models and one bimodal model are studied to determine which model performs best. As it is very difficult to determine the model parameter values without the assistance of a computer, because of the equations’ complexity, a software package has been developed based on the Matlab platform. A database of 21 soil specimens with pre-fitted PSD curves and 13 soil specimens with a number of experimental data are studied to evaluate the performance of these models. The results indicate that most of the gap-graded soil PSD curves can be correctly represented using the Fredlund bimodal parametric (FBP) model, while all the well-graded soil PSD curves can be represented using both the FBP and Fredlund 4 parametric (F4P) models.

DEM Modeling of Particle Breakage in Silica Sands under One-Dimensional Compression

A Discrete Element Method (DEM) model is developed to study the particle breakage effect on the one-dimensional compression behavior of silica sands. The ‘maximum tensile stress’ breakage criterion considering multiple contacts is adopted to simulate the crushing of circular particles in the DEM. The model is compared with published experimental results. Comparison between the compression curves obtained from the numerical and experimental results shows that the proposed method is very effective in studying the compression behavior of silica sands considering particle breakage. The evolution of compression curves at different stress levels is extensively studied using contact force distribution, variation of contact number and particle size distribution curve with loading. It is found that particle breakage has great impact on compression behavior of sand, particularly after the yield stress is reached and particle breakage starts. The crushing probability of particles is found to be macroscopically affected by stress level and particle size distribution curve, and microscopically related to the evolutions of contact force and coordination number. Once the soil becomes well-graded and the average coordination number is greater than 4 in two-dimension, the crushing probability of parent particles can reduce by up to 5/6. It is found that the average contact force does not always increase with loading, but increases to a peak value then decreases once the soil becomes more well-graded. It is found through the loading rate sensitivity analysis that the compression behavior of sand samples in the DEM is also affected by the loading rate. Higher yield stresses are obtained at higher loading rates.

Triaxial tests of soil–rock mixtures with different rock block distributions

Triaxial tests on three types of soil–rock mixture (S-RM) samples with the same rock block content, but different grain size distributions, were performed in this study. To better understand the meso-mechanical behavior of soil–rock mixtures, one set of samples containing “oversized rock blocks” was designed. The oversized rock blocks in the other two sets were handled using the equivalent weight replacement method and the similar translation method. On this basis, the effect of the grain size distribution on the mechanical properties of the soil–rock mixtures was explored. The interlocking and the breakage of the large rock blocks were found to be two of the controlling factors of the mechanical properties of soil–rock mixtures. The deviator stress and the volumetric strain correlated well with the uniformity coefficient of the particle size distribution curve and performed differently under different confining pressure levels. Based on X-ray computed tomography (CT) slices of samples taken during the triaxial tests, the interaction of the internal rock blocks and the evolution of the sample meso-structure in the loading process were observed and analyzed; the present analysis provides explanations for the macroscopic mechanical behavior of soil–rock mixtures.

Compression characteristics of an artificially mixed soil from confined uniaxial compression tests

The present study focuses on the compression characteristics of a crushed sandstone–mudstone particle mixture. The mixture is artificially prepared by mixing sandstone particles and mudstone particles (MP) on the basis of five scheduled particle size distribution (PSD) curves and six MP contents by weight. In order to investigate the compression characteristics, 120 confined uniaxial compression tests are performed. The compression curve for each specimen, which represents the relationship between the logarithm (base 10) of the applied stress and void ratio, is obtained from test data. Two defining features of the compression curve, namely the compression index (I c) and pre-compression stress (σ p), are determined. The effects of two-type factors on the two parameters I c and σ p are analyzed. Factors of the first type are the properties of tested material, which include the PSD curve [the characteristics of which are denoted by the median particle diameter (D 50), gravel content (G c), non-uniformity coefficient (C u), curvature coefficient (C c), characteristic size (α), PSD shape (β)], and MP content by weight (MPc). Factors of the other type are the properties of the specimen, which include the initial water content (w), initial dry bulk density (ρ d), and initial void ratio (e 0). The results indicate that both the parameters I c and σ p are correlative with the properties of the tested material and specimen.

Comparison of Separate and Co-grinding of the Blended Cements with the Pozzolanic Component

The main difference between separate and co-grinding of blended cement is the fact that co-grinding occurs interaction among the milled components. These interactions may speed up milling process, or on the contrary to slow it down. It depends on grindability of the components. Separate grinding and subsequent homogenization is more common. High speed disintegrator appears to be a promising technology for the homogenization of blended cements after separate milling process in traditional mills, which can be associated with final grinding. The aim of the work was to compare the effect of separate and co-grinding, and their combinations on the properties of the blended cement. At first the samples of pure glass, pure Portland cement and its mixture were pre-ground in the ball mill to the specific surface area of 400 m2/kg according to Blaine. The material was subsequently ground either in a ball mill or disintegrator by the various combinations of separate or co-grinding. All the samples were subjected to granulometric and morphological analysis and the analysis of the technological properties. In the case of the combination of cement and glass the co-grinding appeared to be more advantageous than the separate grinding with homogenization. The high speed disintegrator has produced sharp-edged grains with narrower particle size distribution curve than traditional ball mill. Technological properties of the cement have been also influenced by high speed disintegrator. Compressive strength in early age was higher than in the case of ball mill type cement, however, the final strength were essentially the same.

Effects of suffusion in embankment dam filters

This study investigates how varying degrees of internal instability of silt–sand–gravel soils affect the grading characteristics due to suffusion. Suffusion is an initiation mechanism of internal erosion, which is a major cause of the failure of embankment dams. A database comprising gradations representative of those used for embankment dam filters has been compiled. Three are based on downward seepage tests by the authors and the remaining 23 are based on reported results of tests published by others. These 26 gradations are cohesionless sand–gravel soils and silt–sand–gravel soils with < 15% fines, some of which have slightly plastic fines. Internal stability is evaluated using two empirical criteria for shape analysis of the particle size distribution curve. By relating the internal stability to typical grading characteristics, the effects of internal instability are determined. Gradually, more severe effects are observed as the internal instability increases. For clearly unstable soils, with a stability index (H/F)min < 0·5 and a probability of internal instability pinitial > 70%, the effective grain size D15 is increased, on average, by a factor of 9 relative to its initial value. Coarsening of a critical filter to an impervious dam core may adversely affect the filter's protective ability.

Determination of the Physical, Chemical, and Hydraulic Characteristics of Locally Available Materials for Formulating Extensive Green Roof Substrates

Several locally available materials were tested to create an optimized growth substrate for arid and semiarid Mediterranean extensive green roofs. The study involved a four-step screening procedure. At the first step, 10 different materials were tested including pumice (Pum), crushed tiles grade 1–2 mm (T1–2), 2–4 mm (T2–4), 5–8 mm (T5–8), 5–16 mm (T5–16), and 4–22 mm (T4–22); crushed bricks of either 2–4 mm (B2–4) or 2–8 mm (B2–8); a thermally treated clay (TC); and zeolite (Zeo). All materials were tested for their particle size distribution, pH, and electrical conductivity (EC). The results were compared for compliance with existing guidelines for extensive green roof construction. From the first step, the most promising materials were shown to include Pum, Zeo, T5–8, T5–16, and TC, which were then used at the second stage to develop mixtures between them. Tests at the second stage included particle size distribution and moisture potential curves. Pumice mixed with TC provided the best compliance with existing guidelines in relation to particle size distribution, and it significantly increased moisture content compared with the mixes of Pum with T5–8 and T5–16. As a result, from the second screening step, the best performing substrate was Pum mixed with TC and Zeo. The third stage involved the selection of the most appropriate organic amendment of the growing substrate. Three composts having different composition and sphagnum peat were analyzed for their chemical and physical characteristics. The composts were a) garden waste compost (GWC), b) olive (Olea europaea L.) mill waste compost (OMWC), and c) grape (Vitis vinifera L.) marc compost (GMC). It was found that the peat-amended substrate retained increased moisture content compared with the compost-amended substrates. The fourth and final stage involved the evaluation of the environmental impact of the final mix with the four different organic amendments based on their first flush nitrate nitrogen (NO3−-N) leaching potential. It was found that GWC and OMWC exhibited increased NO3−-N leaching that initially reached 160 and 92 mg·L−1 of NO3−-N for OMWC and GWC, respectively. By contrast, peat and GMC exhibited minimal NO3−-N leaching that was slightly above the maximum contaminant level of 10 mg·L−1 of NO3−-N (17.3 and 14.6 mg·L−1 of NO3−N for peat and GMC, respectively). The latter was very brief and lasted only for the first 100 and 50 mL of effluent volume for peat and GMC, respectively.

농경유역 중소하천에서 유량과 총유사량의 관계식 유도방법

본 연구는 농경유역 중소하천의 주요 지점에서 실측된 현장자료를 사용하여 유량과 총유사량 관계곡선과 이들 간의 관계식을 유도한다. 실측치 총유사량 자료는 수심평균농도와 하상에서 각각의 부유사와 소류사 채취기(DH-48, D-74 및 BLH-84, BL-84)에 의해 채집된 시료를 건조 또는 여과법, 체분석에 의한 입도분포곡선을 통해 얻은 부유사량에 소류사량을 합하여 얻었다. 이들 현장자료는 농경유역 논산수계 내 4개 대상하천의 국가-지방하천 수로구간 7개 측점에서 2012년 8월부터 2014년 9월까지 측정되었다. 그 결과, 유량과 총유사량에 대한 관계곡선과 관계식은 현장측정 자료군의 분포특성을 분석함으로써 멱함수형으로 유도하였으며, 이들 관계식은 수공 유사공학의 이론적 연구뿐만 아니라 실무적 응용에 있어 세굴, 퇴적 및 이송을 해석하는데 유용한 도구로 사용될 수 있을 것이다. This study aims to derivate of the relationship and rating curve for the flow discharge-total sediment using the measured field data from the main points of small-medium stream reaches in agrarian basin. The total sediment of measured data are obtained by bed load added to suspended load which analyzed using the particle size distribution curve of sieve test and the dry or the filtration method from the collected samples by samplers (DH-48, D-74 and BLH-84, BL-84) at the stream bed and the depth-averaged concentration, respectively. These field data had been collected from August 2012 to September 2014 at the seven measuring stations of the national-local channel reaches of the four study streams in the Nonsan river systems of agrarian basin. As a result, the relationships and the rating curve for the flow discharge-total sediment are derived as a function pattern of power law by analyzing on a distribution characteristic of the database set and it will be used as a useful tool to analyze erosion, deposition, and transportation in theoretical research as well as in practical application of the hydraulic sedimentation engineering.

Quantifying the effect of clinker grinding aids under laboratory conditions

The effect of clinker grinding aids (GAs) on mill performance and cement properties is currently quantified in real-scale grinding plants. In fact, laboratory-grinding mills operated for given time interval do not consider the effect of circulating load, thereby leading to increased specific energy consumption (Ec) with excessively wide cement particle size distribution (PSD) curves. The main objective of this paper is to develop and validate a laboratory locked-cycle approach that mimics the industrial grinding operations occurring in closed-circuit tube mills. Test results have shown that Ec and its rate of decrease due to GA additions can be adequately predicted using this approach, when compared to those resulting from a real mill operating at 90ton/h. The addition of GA led to narrower PSD curves and shifting towards smaller diameters, just like what happens in industrial grinding. Also, the cement properties including water demand, setting time, and compressive strength matched to a large extent within each other.

Geotechnical Properties of Some Soils in a Tar Sand Area of Southwestern Nigeria

Engineering properties of some soil samples in Idiobilayo and Idiopopo areas of Southwestern Nigeria were studied with the aim of determining their geotechnical properties which can aid in the exploitation plan of the tar sands deposits in the area. A total of six sampling locations with three samples each were established in the study area. Samples of soil both disturbed and undisturbed were obtained from the trial pits to a depth of about 1.5m at 0.5m vertical interval. The disturbed samples were subsequently subjected to classification tests such as grain size distribution and consistency limits using British standards 1377 procedure. However, the undisturbed samples were subjected to permeability test. Results obtained in this study showed that the area of study is underlain essentially by sandy soils, with substantial silty content. Clay and gravel content are quite minimal. The particle size distribution curves confirmed a general dominance of silt to coarse-grained sand size particles in the soil matrix with minor but complimentary clayey and gravelly materials. Amounts of fines in the soils are less than 50% except in trial pts 4 and 5 where they are slightly above 50%. The soils consist of sand (60.0 %) and silt (35.0 %). The percentage of fines (silt and clay sized fraction) in the soils was about 38.0 %, and makes the soils good base for landfill, since recommended percentage of fines, should not be less than 20.0 %. However the obtained values of permeability coefficient of 5.5 X 10 -6 mm/s to 1.2 X 10 -4 mm/s call for the lining of the base to avoid groundwater pollution by leachates.

Rheological behaviour of concrete made with fine recycled concrete aggregates – Influence of the superplasticizer

This paper evaluates the influence of two superplasticizers (SP) on the rheological behaviour of concrete made with fine recycled concrete aggregates (FRCA). Three families of concrete were tested: family C0 made without SP, family C1 made with a regular superplasticizer and family C2 made with a high-performance superplasticizer. Five replacement ratios of natural sand by FRCA were tested: 0%, 10%, 30%, 50% and 100%. The coarse aggregates were natural gravels. Three criteria were established to design the concrete mixes’ composition: keep the same particle size distribution curves, adjust the water/cement ratio to obtain a similar slump and no pre-saturation of the FRCA. All mixes had the same cement and SP content. The results show that the incorporation of FRCA significantly increased the shrinkage and creep deformation. The FRCA’s effect was influenced by the curing age. The reference concrete made with natural sand stabilizes the creep deformation faster than the mixes made with FRCA. The incorporation of superplasticizer increased the shrinkage at early ages and decreased the shrinkage at 91days of age. The regular superplasticizer did not improve the creep deformation while the high-performance superplasticizer highly improved this property. The incorporation of FRCA jeopardized the SP’s effectiveness. This study demonstrated that to use FRCA and superplasticizer for concrete production it is necessary to take into account the different rheological behaviour of these mixes.

Synthesis and Characterization of Hydroxyl-Functionalized Polystyrene Microspheres With Monodispersity

Hydroxyl-functionalized polystyrene (HFPS) microspheres were prepared by the copolymerization of styrene (St) and hydroxyethyl acrylate (HEA) via dispersion polymerization in the absence of steric stabilizers. The copolymerization was conducted with V-50 as an initiator. The effect of initiator concentration, HEA amount, and medium composition on the average diameters and coefficient variations of HFPS microspheres were systematically investigated. The particle morphology, the average diameters, the surface N content, and the particle size distribution curves were measured by SEM, XPS, and laser particle size analyzer. The results indicated that monodisperse HFPS microspheres with diameter of 0.6–1.0 μm could be successfully generated by dispersion polymerization of St and HEA without steric stabilizers. Therefore, overall, the present manuscript provided a simple route to generate monodisperse hydroxyl-functionalized polymer microspheres.