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Sieve analysis
View on Wikipedia| Granulometry | |
|---|---|
| Basic concepts | |
| Particle size, Grain size, Size distribution, Morphology | |
| Methods and techniques | |
| Mesh scale, Optical granulometry, Sieve analysis, Soil gradation | |
Related concepts | |
| Granulation, Granular material, Mineral dust, Pattern recognition, Dynamic light scattering | |
A sieve analysis (or gradation test) is a practice or procedure used in geology, civil engineering,[1] and chemical engineering[2] to assess the particle size distribution (also called gradation) of a granular material by allowing the material to pass through a series of sieves of progressively smaller mesh size and weighing the amount of material that is stopped by each sieve as a fraction of the whole mass.
The size distribution is often of critical importance to the way the material performs in use. A sieve analysis can be performed on any type of non-organic or organic granular materials including sand, crushed rock, clay, granite, feldspar, coal, soil, a wide range of manufactured powder, grain and seeds, down to a minimum size depending on the exact method. Being such a simple technique of particle sizing, it is probably the most common.[3]
Procedure
[edit]A gradation test is performed on a sample of aggregate in a laboratory. A typical sieve analysis uses a column of sieves with wire mesh screens of graded mesh size.
A representative weighed sample is poured into the top sieve which has the largest screen openings. Each lower sieve in the column has smaller openings than the one above. At the base is a pan, called the receiver.
The column is typically placed in a mechanical shaker, which shakes the column, usually for a set period, to facilitate exposing all of the material to the screen openings so that particles small enough to fit through the holes can fall through to the next layer. After the shaking is complete the material on each sieve is weighed. The mass of the sample of each sieve is then divided by the total mass to give a percentage retained on each sieve. The size of the average particle on each sieve is then analysed to get a cut-off point or specific size range, which is then captured on a screen.
The results of this test are used to describe the properties of the aggregate and to see if it is appropriate for various civil engineering purposes such as selecting the appropriate aggregate for concrete mixes and asphalt mixes as well as sizing of water production well screens.
The results of this test are provided in graphical form to identify the type of gradation of the aggregate. The complete procedure for this test is outlined in the American Society for Testing and Materials (ASTM) C 136[4] and the American Association of State Highway and Transportation Officials (AASHTO) T 27[5]
A suitable sieve size for the aggregate underneath the nest of sieves to collect the aggregate that passes through the smallest. The entire nest is then agitated, and the material whose diameter is smaller than the mesh opening pass through the sieves. After the aggregate reaches the pan, the amount of material retained in each sieve is then weighed.[6]
Preparation
[edit]In order to perform the test, a sufficient sample of the aggregate must be obtained from the source. To prepare the sample, the aggregate should be mixed thoroughly and be reduced to a suitable size for testing. The total mass of the sample is also required.[6]
Results
[edit]
The results are presented in a graph of percent passing versus the sieve size. On the graph the sieve size scale is logarithmic. To find the percent of aggregate passing through each sieve, first find the percent retained in each sieve. To do so, the following equation is used,
%Retained = ×100%
where WSieve is the mass of aggregate in the sieve and WTotal is the total mass of the aggregate. The next step is to find the cumulative percent of aggregate retained in each sieve. To do so, add up the total amount of aggregate that is retained in each sieve and the amount in the previous sieves. The cumulative percent passing of the aggregate is found by subtracting the percent retained from 100%.
%Cumulative Passing = 100% - %Cumulative Retained.
The values are then plotted on a graph with cumulative percent passing on the y axis and logarithmic sieve size on the x axis.[6]
There are two versions of the %Passing equations. the .45 power formula is presented on .45 power gradation chart, whereas the more simple %Passing is presented on a semi-log gradation chart. version of the percent passing graph is shown on .45 power chart and by using the .45 passing formula.
- .45 power percent passing formula
% Passing = Pi = x100%
Where:
SieveLargest - Largest diameter sieve used in (mm).
Aggregatemax_size - Largest piece of aggregate in the sample in (mm).
- Percent passing formula
%Passing = x100%
Where:
WBelow - The total mass of the aggregate within the sieves below the current sieve, not including the current sieve's aggregate.
WTotal - The total mass of all of the aggregate in the sample.
Methods
[edit]There are different methods for carrying out sieve analyses, depending on the material to be measured.
Throw-action
[edit]Here a throwing motion acts on the sample. The vertical throwing motion is overlaid with a slight circular motion which results in distribution of the sample amount over the whole sieving surface. The particles are accelerated in the vertical direction (are thrown upwards). In the air they carry out free rotations and interact with the openings in the mesh of the sieve when they fall back. If the particles are smaller than the openings, they pass through the sieve. If they are larger, they are thrown. The rotating motion while suspended increases the probability that the particles present a different orientation to the mesh when they fall back again, and thus might eventually pass through the mesh. Modern sieve shakers work with an electro-magnetic drive which moves a spring-mass system and transfers the resulting oscillation to the sieve stack. Amplitude and sieving time are set digitally and are continuously observed by an integrated control-unit. Therefore, sieving results are reproducible and precise (an important precondition for a significant analysis). Adjustment of parameters like amplitude and sieving time serves to optimize the sieving for different types of material. This method is the most common in the laboratory sector.[7]
Horizontal
[edit]In horizontal sieve shaker the sieve stack moves in horizontal circles in a plane. Horizontal sieve shakers are preferably used for needle-shaped, flat, long or fibrous samples, as their horizontal orientation means that only a few disoriented particles enter the mesh and the sieve is not blocked so quickly. The large sieving area enables the sieving of large amounts of sample, for example as encountered in the particle-size analysis of construction materials and aggregates.
Tapping
[edit]
A horizontal circular motion overlies a vertical motion which is created by a tapping impulse. These motional processes are characteristic of hand sieving and produce a higher degree of sieving for denser particles (e.g. abrasives) than throw-action sieve shakers.
Wet
[edit]Most sieve analyses are carried out dry. But there are some applications which can only be carried out by wet sieving. This is the case when the sample which has to be analysed is e.g. a suspension which must not be dried; or when the sample is a very fine powder which tends to agglomerate (mostly < 45 μm) – in a dry sieving process this tendency would lead to a clogging of the sieve meshes and this would make a further sieving process impossible. A wet sieving process is set up like a dry process: the sieve stack is clamped onto the sieve shaker and the sample is placed on the top sieve. Above the top sieve a water-spray nozzle is placed which supports the sieving process additionally to the sieving motion. The rinsing is carried out until the liquid which is discharged through the receiver is clear. Sample residues on the sieves have to be dried and weighed. When it comes to wet sieving it is very important not to change the sample in its volume (no swelling, dissolving or reaction with the liquid).
Air Circular Jet
[edit]Air jet sieving machines are ideally suited for very fine powders which tend to agglomerate and cannot be separated by vibrational sieving. The reason for the effectiveness of this sieving method is based on two components: A rotating slotted nozzle inside the sieving chamber and a powerful industrial vacuum cleaner which is connected to the chamber. The vacuum cleaner generates a vacuum inside the sieving chamber and sucks in fresh air through the slotted nozzle. When passing the narrow slit of the nozzle the air stream is accelerated and blown against the sieve mesh, dispersing the particles. Above the mesh, the air jet is distributed over the complete sieve surface and is sucked in with low speed through the sieve mesh. Thus the finer particles are transported through the mesh openings into the vacuum cleaner.
Types of gradation
[edit]- Dense gradation
- A dense gradation refers to a sample that is approximately of equal amounts of various sizes of aggregate. By having a dense gradation, most of the air voids between the material are filled with particles. A dense gradation will result in an even curve on the gradation graph.[8]
- Narrow gradation
- Also known as uniform gradation, a narrow gradation is a sample that has aggregate of approximately the same size. The curve on the gradation graph is very steep, and occupies a small range of the aggregate.[6]
- Gap gradation
- A gap gradation refers to a sample with very little aggregate in the medium size range. This results in only coarse and fine aggregate. The curve is horizontal in the medium size range on the gradation graph.[6]
- Open gradation
- An open gradation refers an aggregate sample with very little fine aggregate particles. This results in many air voids, because there are no fine particles to fill them. On the gradation graph, it appears as a curve that is horizontal in the small size range.[6]
- Rich gradation
- A rich gradation refers to a sample of aggregate with a high proportion of particles of small sizes.[8]
Types of sieves
[edit]- Woven wire mesh sieves
Woven wire mesh sieves are according to technical requirements of ISO 3310-1.[9] These sieves usually have nominal aperture ranging from 20 micrometers to 3.55 millimeters, with diameters ranging from 100 to 450 millimeters.
- Perforated plate sieves
Perforated plate sieves conform to ISO 3310-2 and can have round or square nominal apertures ranging from 1 millimeter to 125 millimeters.[10] The diameters of the sieves range from 200 to 450 millimeters.
- American standard sieves
American standard sieves also known as ASTM sieves conform to ASTM E11 standard.[11] The nominal aperture of these sieves range from 20 micrometers to 200 millimeters, however these sieves have only 8 inches (203 mm) and 12 inches (305 mm) diameter sizes.
Limitations of sieve analysis
[edit]Sieve analysis has, in general, been used for decades to monitor material quality based on particle size. For coarse material, sizes that range down to #100 mesh (150 μm), a sieve analysis and particle size distribution is accurate and consistent.
However, for material that is finer than 100 mesh, dry sieving can be significantly less accurate. This is because the mechanical energy required to make particles pass through an opening and the surface attraction effects between the particles themselves and between particles and the screen increase as the particle size decreases. Wet sieve analysis can be utilized where the material analyzed is not affected by the liquid - except to disperse it. Suspending the particles in a suitable liquid transports fine material through the sieve much more efficiently than shaking the dry material.
Sieve analysis assumes that all particle will be round (spherical) or nearly so and will pass through the square openings when the particle diameter is less than the size of the square opening in the screen. For elongated and flat particles a sieve analysis will not yield reliable mass-based results, as the particle size reported will assume that the particles are spherical, where in fact an elongated particle might pass through the screen end-on, but would be prevented from doing so if it presented itself side-on.
Properties
[edit]Gradation affects many properties of an aggregate, including bulk density, physical stability and permeability. With careful selection of the gradation, it is possible to achieve high bulk density, high physical stability, and low permeability. This is important because in pavement design, a workable, stable mix with resistance to water is important. With an open gradation, the bulk density is relatively low, due to the lack of fine particles, the physical stability is moderate, and the permeability is quite high. With a rich gradation, the bulk density will also be low, the physical stability is low, and the permeability is also low. The gradation can be affected to achieve the desired properties for the particular engineering application.[8]
Engineering applications
[edit]Gradation is usually specified for each engineering application it is used for. For example, foundations might only call for coarse aggregates, and therefore an open gradation is needed. Sieve analysis determines the particle size distribution of a given soil sample and hence helps in easy identification of a soil's mechanical properties. These mechanical properties determine whether a given soil can support the proposed engineering structure. It also helps determine what modifications can be applied to the soil and the best way to achieve maximum soil strength.
See also
[edit]References
[edit]- ^ Amsterdam, Errol Van (2000). Construction Materials for Civil Engineering. Juta and Company Ltd. p. 16. ISBN 978-0-7021-5213-9.
- ^ Albright, Lyle (2008-11-20). Albright's Chemical Engineering Handbook. CRC Press. p. 1718. ISBN 978-0-8247-5362-7.
- ^ p231 in "Characterisation of bulk solids" by Donald Mcglinchey, CRC Press, 2005.
- ^ ASTM International - Standards Worldwide. (2006). ASTM C136-06. http://www.astm.org/cgi-bin/SoftCart.exe/DATABASE.CART/REDLINE_PAGES/C136.htm?E+mystore
- ^ AASHTO The Voice of Transportation. T0 27. (2006). https://bookstore.transportation.org/item_details.aspx?ID=659
- ^ a b c d e f Pavement Interactive. Gradation Test. (2007). https://pavementinteractive.org/index.php?title=Gradation_Test
- ^ Texas Department of Transportation (January 2016). "Test Procedure for Sieve Analysis of Fine and Coarse Aggregates" (PDF). Texas DOT. Retrieved 2016-12-24.
- ^ a b c M.S. Mamlouk and J.P. Zaniewski, Materials for Civil and Construction Engineers, Addison-Wesley, Menlo Park CA, 1999
- ^
ISO/TC 24/SC 8. Test sieves -- Technical requirements and testing -- Part 1: Test sieves of metal wire cloth. ISO 3310-1:2000. ISO. p. 15.
{{cite book}}: CS1 maint: numeric names: authors list (link) - ^
ISO/TC 24/SC 8. Test sieves -- Technical requirements and testing -- Part 2: Test sieves of perforated metal plate. ISO 3310-2:2013. ISO. p. 9.
{{cite book}}: CS1 maint: numeric names: authors list (link) - ^
Subcommittee: E29.01. Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves. ASTM E11 - 13. ASTM International. p. 9.
{{cite book}}: CS1 maint: numeric names: authors list (link)
External links
[edit]Sieve analysis
View on GrokipediaFundamentals
Definition and Principles
Sieve analysis is a fundamental technique for determining the particle size distribution of granular materials by mechanically separating particles using a stack of sieves featuring progressively smaller mesh openings, typically under agitation to facilitate passage based on size.[11][12] This method is particularly effective for particles ranging from approximately 0.075 mm to coarser sizes, where the sieves act as barriers that retain larger particles while allowing smaller ones to pass through.[11] The underlying principles of sieve analysis rely on mechanical forces such as gravity and vibration to drive particle movement, ensuring that particles align and pass through apertures corresponding to their dimensions during shaking or tapping.[12] In wet sieving variants, fluid dynamics aid dispersion and prevent clogging of the meshes.[12] Particle size in sieve analysis is approximated using the equivalent spherical diameter, defined as the diameter of a hypothetical sphere with the same settling or passage behavior as the actual particle, providing a standardized metric despite irregular shapes.[13] The sieve aperture, standardized in series like the U.S. Standard or ISO, serves as the primary sizing reference, representing the nominal opening width through which particles must pass.[12] Key assumptions include that particles are rigid and non-cohesive to avoid agglomeration or deformation, and that they are processed in a dry state unless wet conditions are explicitly applied to handle fines or cohesive materials.[12]Historical Development
The origins of sieve analysis trace back to ancient civilizations, where rudimentary sieves were employed for particle separation in agriculture and mining. In ancient Egypt, woven reed sieves were used to grade harvested grains by size, facilitating efficient storage and processing. Similarly, Roman bakers utilized linen sieves to refine flour from milled grain, removing coarser bran particles to produce finer textures for bread-making. In mining operations, sieving techniques for separating ores were documented as early as the 16th century in Georgius Agricola's seminal work De re metallica (1556), which described manual sifting methods to isolate valuable minerals from debris. The 19th century marked the formalization of sieve analysis as a scientific method, particularly in soil testing and materials characterization. The term "mechanical analysis" emerged around 1800, with early combinations of sieving and decantation techniques developed by 1805 to quantify particle distributions in soils and sediments. By the late 1800s, advancements in manufacturing led to the widespread adoption of woven wire cloth sieves, offering greater precision and durability over traditional woven fabrics; these became standard for industrial particle sizing in engineering applications. Key progress in the early 20th century included the introduction of the Ro-Tap mechanical sieve shaker in 1914 by W.S. Tyler, which automated the shaking process to improve reproducibility and efficiency in laboratory settings. Standardization efforts accelerated in the mid-20th century, with the American Society for Testing and Materials (ASTM) approving E11 in 1925 to specify requirements for woven wire test sieve cloth and construction, ensuring consistent aperture sizes from 125 mm down to 20 μm. Post-World War II innovations shifted from manual hand-shaking to fully motorized devices, enhancing throughput for large-scale testing in construction and manufacturing. The International Organization for Standardization (ISO) contributed to global harmonization with ISO/R 565 in 1967, defining nominal aperture sizes for test sieves and promoting uniformity across international practices. In the 2000s, sieve analysis evolved further through the integration of digital imaging and automated systems, allowing for real-time particle tracking and reduced human error in distribution analysis.Procedure
Sample Preparation
Sample preparation is a critical initial step in sieve analysis to ensure that the test sample accurately represents the bulk material and is in a condition suitable for effective particle separation. Proper preparation minimizes biases introduced by uneven distribution, moisture, or agglomeration, which could otherwise skew the particle size distribution results. This involves obtaining a representative subsample from the larger field or stockpile sample, followed by conditioning to remove impurities and achieve a uniform state. Standards such as ASTM C136 for aggregates and ASTM D6913 for soils provide detailed guidelines to standardize these processes across applications in civil engineering, geotechnical testing, and materials science.[14] Sampling techniques focus on reducing the bulk material to a manageable test portion while preserving the original particle size distribution. Representative subsamples are typically obtained using mechanical riffle splitters, which divide the material into equal portions by channeling it through alternating chutes, or by quartering, where the sample is spread into a cone, flattened, and divided into four equal parts with two opposite quarters selected and the process repeated. These methods ensure statistical homogeneity, particularly for heterogeneous materials like soils or aggregates. For aggregates, ASTM C702 specifies reduction methods including riffle splitting for particles up to 37.5 mm, while quartering is suitable for larger or moist samples. Minimum sample masses are prescribed based on the maximum particle size to achieve reliable results; for example, ASTM D6913 specifies minimum dry specimen masses ranging from 100 g to 10 kg depending on the maximum particle size (99% or more passes the sieve), as detailed in Table 2 of the standard (e.g., 500 g for maximum sizes up to 19 mm, 10 kg for up to 75 mm), to ensure sufficient material on each sieve level without overloading.[15][16] Cleaning and drying prepare the sample by eliminating contaminants and moisture that could cause particles to clump or alter during sieving. Organic matter, such as roots or humus in soil samples, is manually removed or dispersed chemically if necessary, while adherent fines are washed off using water for aggregates per ASTM C136, followed by thorough drying. The sample is then oven-dried to constant mass to prevent agglomeration; for aggregates, this is typically at 110 ± 5°C, whereas sensitive soils may require lower temperatures not exceeding 60°C to avoid altering clay mineral structures or organic components. Overheating is avoided to preserve particle integrity, with drying times varying from hours to days based on sample size and initial moisture content. For cohesive soils, dispersion methods like mechanical pulverization with a mortar and pestle or ultrasonic baths are employed to break down aggregates without fracturing primary particles, ensuring individual grains are analyzed. Ultrasonic dispersion, applied for 5-10 minutes at frequencies around 20-50 kHz, effectively disaggregates clayey materials by sonic vibration, as demonstrated in studies on soil particle separation.[14][17] Particle size range considerations involve pre-screening to adapt the sample to the sieve stack's capabilities. Coarse materials exceeding 75 mm, such as large aggregates, are pre-screened using larger sieves or manual separation to fit within the standard stack, preventing damage to finer sieves and ensuring even distribution. For fine or cohesive fractions, wet dispersion techniques may be integrated if dry methods fail to separate particles adequately, though the primary focus remains on dry preparation for most sieve analyses. This step aligns the sample with the equipment's limits, typically covering sizes from 125 mm down to 75 μm. Safety and quality controls are integral to reliable preparation, emphasizing operator protection and result reproducibility. Protective gear, including gloves, safety goggles, and dust masks, must be worn to handle potentially hazardous dusts from drying or dispersion, particularly with siliceous soils that pose silica exposure risks. Quality is maintained by preparing at least three replicate samples for statistical analysis, allowing assessment of variability and compliance with precision statements in standards like ASTM D6913, which require coefficients of variation below 5% for key fractions. Documentation of all steps, including mass measurements to 0.1 g accuracy, ensures traceability and validates the representativeness of the prepared sample.[14]Sieving Execution
The sieving execution begins with the assembly of the sieve stack. Sieves are nested in order of decreasing aperture size, with the largest opening at the top to receive the prepared sample, progressing to finer meshes, and a bottom pan to collect the finest particles passing the smallest sieve. For example, in the analysis of fine aggregates such as sand, the top sieve typically has a 4.75 mm opening, followed by progressively smaller sizes down to 75 μm or finer. The stack is secured using clamps or a mechanical shaker frame to ensure stability during agitation.[18] Agitation of the assembled stack follows to separate particles by size. This can be performed manually by inclining the stack and applying approximately 150 strokes per minute with a 1/6 revolution every 25 strokes, or mechanically using a sieve shaker that provides uniform motion, such as vertical tapping combined with horizontal circular movement. Mechanical agitation is recommended for samples exceeding 20 kg to ensure particles tumble and orient in various directions for effective separation. The process continues for a typical duration of 10-15 minutes in mechanical sieving, or until an endpoint is reached where no more than 1% of the material by mass passes through any sieve during an additional 1 minute of agitation.[19] Once agitation is complete, fractions are collected by carefully removing material retained on each sieve. Each sieve is weighed individually with its retained particles to the nearest 0.1% of the original sample mass, ensuring all residues are accounted for. To dislodge any adhering particles without damaging the mesh, a soft brush or tapping with a mallet is used gently on the sieve surface. The bottom pan's contents represent the fines passing the smallest sieve.[19][18] Quality checks are essential to validate the sieving execution. A visual inspection of each sieve confirms complete separation, with no significant clumping or overload evident. The total recovered mass must balance the initial sample mass within 0.3%; discrepancies exceeding this threshold invalidate the results and necessitate re-sieving.[18][20]Data Analysis
Particle Size Distribution
Particle size distribution (PSD) in sieve analysis refers to the proportion of particles within specified size ranges, typically expressed as mass percentages of material retained on or passing through each sieve relative to the total sample mass. This distribution quantifies the range and relative amounts of particle sizes in a granular material, such as soil, aggregates, or powders, providing essential data for material characterization in fields like geotechnical engineering and materials science.[11][14] Data from sieve analysis is commonly presented in tabular form, listing sieve sizes, mass retained on each sieve, percentage retained, and cumulative percentage passing, with totals summing to 100% of the initial sample mass. For instance, using U.S. Standard sieve designations, a typical table might include sizes such as #4 (4.75 mm), #8 (2.36 mm), #16 (1.18 mm), #30 (0.60 mm), #50 (0.30 mm), #100 (0.15 mm), and #200 (0.075 mm), along with the pan for material finer than the smallest sieve. An example for a 500 g soil sample could show:| Sieve Size | Opening (mm) | Mass Retained (g) | % Retained | % Passing |
|---|---|---|---|---|
| #4 | 4.75 | 50 | 10 | 90 |
| #8 | 2.36 | 100 | 20 | 70 |
| #16 | 1.18 | 150 | 30 | 40 |
| #30 | 0.60 | 100 | 20 | 20 |
| #50 | 0.30 | 50 | 10 | 10 |
| #100 | 0.15 | 25 | 5 | 5 |
| #200 | 0.075 | 15 | 3 | 2 |
| Pan | <0.075 | 10 | 2 | 0 |
| Total | - | 500 | 100 | - |
