Sieve Analysis

What Is Sieve Analysis?

Sieve Analysis (a.k.a. grain-size analysis) determines the particle-size distribution of soils by passing a representative sample through a stack of standard sieves and weighing material retained on each. The resulting gradation informs classification (USCS/AASHTO), compaction behavior, permeability trends, filter criteria, and constructability. It is a cornerstone of Soil Mechanics and underpins downstream tasks like Standard Proctor Test, Compaction Test, and Permeability Test.

Sieve data, together with fines characterization (Atterberg Limits), drive engineering choices for Geotechnical Earthworks, Shallow Foundations, and drainage layers that may include Geosynthetics.

A defensible gradation curve is the fastest way to anticipate how a soil will compact, drain, filter, and support loads.

Standards, Sieve Stack & Sample Prep

Durable, globally referenced procedures include ASTM International and agency guidance such as FHWA and USACE. Typical references:

ASTM D6913/D6913M: Particle-size distribution of soils using sieve analysis (coarse fraction).
ASTM D7928: Particle-size distribution of fine-grained soils by hydrometer (complements sieves; see the “Fines” section).
ASTM D421/D7928 prep concepts: Drying, breaking down clods without crushing particles, and washing procedures to remove coatings/fines.

A standard stack typically includes (top→bottom): 3″, 2″, 1½″, 1″, ¾″, ½″, ⅜″, No.4 (4.75 mm), No.10, No.20, No.40, No.60, No.100, No.200 (75 μm), and a pan. Choose sieves around expected D_max and desired resolution. Representative sample mass scales with top sieve size (e.g., several kg for coarse soils).

Link to Your Program

Plan gradation with your Site Characterization locations and logs; document test IDs for seamless Geotechnical Reporting and Data Analysis.

Step-by-Step Sieve Analysis Procedure

The following workflow aligns with common ASTM practice; always consult the exact standard adopted for your project.

1) Dry & Weigh: Oven-dry at 110 ± 5 °C (unless organics are present), cool in desiccator, and record total dry mass M.
2) Disaggregate: Gently break down clods with a rubber pestle or by hand—do not crush individual grains.
3) Wet Wash (if required): Wash through the No.200 to remove coatings/fines; dry again and record fines loss for mass balance.
4) Stack & Shake: Arrange sieves top (largest) to pan; place sample on the top sieve. Mechanically shake for the standard duration (often 10–15 min) with a compatible amplitude; hand tapping to finish is allowed per method.
5) Brush & Recover: Carefully brush each sieve; avoid forcing particles through undersized apertures. Weigh mass retained on each sieve m_i.
6) Check Mass: Sum retained plus pan; confirm within allowable tolerance (typically ≤ 0.5% of M).
7) Record & Plot: Compute percent retained and percent passing; plot on semi-log paper (size log scale, % passing linear).

Did you know?

For gap-graded soils, extra intermediate sieves reduce aliasing and reveal “valleys” between modes that matter for filter and drainage performance.

Core Calculations, Gradation Indices & How to Read the Curve

Convert masses to percentages, build the cumulative passing curve, and extract characteristic diameters and coefficients used throughout geotechnical design.

Percent Retained & Percent Passing

\( \%R_i = \frac{m_i}{M}\times100 \quad;\quad \%P_i = 100 – \sum_{j\le i}\%R_j \)

\(m_i\)Mass on sieve i

\(M\)Total dry mass

Characteristic Sizes

\( D_{10}, D_{30}, D_{60} \text{ from the curve at 10%, 30%, 60% passing} \)

\(D_{10}\)Effective size

\(D_{60}\)Control size for gradation spread

Uniformity & Curvature

\( C_u = \frac{D_{60}}{D_{10}} \quad;\quad C_c = \frac{D_{30}^2}{D_{10}\,D_{60}} \)

\(C_u\)Uniformity coefficient

\(C_c\)Coefficient of curvature

For USCS classification (coarse fraction), well-graded sands usually require \( C_u \ge 6 \) and \( 1 \le C_c \le 3 \); for gravels, \( C_u \ge 4 \). Combine with fines content and plasticity to assign final symbols (e.g., GW, GP, SW, SP, SM, SC). Use your Atterberg and hydrometer results to resolve silts (M) vs. clays (C).

Reading the Curve

Steep curves indicate uniform material (prone to segregation and lower stability); flatter curves indicate well-graded soils (better compactability and interlock). A “kink” near No.200 signals fines sensitivity that affects Permeability and frost/heave behavior.

What About Fines? Hydrometer & Combined Curves

Below the No.200 sieve (75 μm), sedimentation methods quantify silt and clay sizes. ASTM D7928 (hydrometer) derives a continuous curve for the fine fraction by tracking suspension density versus time and depth. The sieve and hydrometer curves are merged at an overlap point (often No.200) to produce a full gradation spanning gravel → clay.

Concept: Sedimentation & Stokes’ Law

\( v = \frac{(G_s-1)\,g\,d^2}{18\,\nu} \)

\(G_s\)Specific gravity of solids

\(d\)Particle diameter

\( \nu \)Kinematic viscosity

Interpret fines using plasticity: pair the combined gradation with Atterberg Limits to distinguish silts vs. clays and assess Expansive Soils risk. For design, fines content often governs filter criteria, drainage layer selection, and erosion susceptibility.

QA/QC, Good Practice & Common Pitfalls

Reliable gradations demand mass balance, appropriate sample size, correct washing, and consistent handling. Embed these checks in your lab QA plan and link results directly to construction specs.

Mass balance: Sum of retained + pan within tolerance (≤ 0.5% of M typical). Re-run if out of spec.
Sample representativeness: Quartering or riffle-splitting; watch for segregation of coarse particles.
Washing protocol: If coatings/fines are present, wet wash through No.200; document the washed-out mass.
Sieve condition: Check for tears and clogging; calibrate opening sizes periodically.
Shaker settings: Use method-compliant amplitude/time; excessive shaking can abrade particles and bias fines high.
Reporting: Include raw masses, % retained/passing, curve, D-sizes, C_u/C_c, washing notes, and sample origin. Tie into Geotechnical Reporting.

Important

Don’t crush grains to “make them pass.” Disaggregate clods only. For materials with weak cementation, note degradation and consider LA abrasion or durability checks separately.

How Sieve Analysis Informs Design & Construction

Gradation is a gateway parameter across geotechnical and pavement decisions. Use it to classify, model, and specify materials with confidence.

USCS/AASHTO Classification: Combine % fines and plasticity to assign soil groups for design assumptions and specifications.
Compaction targets: Well-graded materials typically achieve higher dry densities; coordinate with Standard Proctor and field Compaction Tests.
Permeability & drainage: Use D₁₀ trends to anticipate Permeability; specify drainage blankets and underdrains accordingly.
Filter and riprap design: Apply filter rules (e.g., ratios using base soil D₁₅, filter D₁₅) and gradation bands for protection layers.
Foundations & bearing: Coarse, dense fills often support higher Bearing Capacity with lower settlements; fines increase compressibility and frost susceptibility.
Earthworks constructability: Gap-graded or uniform sands may segregate and ravel on slopes—see Geotechnical Earthworks.

Real-World Example: Subbase Spec Review

A pavement subbase submittal shows a curve drifting outside the specified gradation band—too uniform around 4.75–2.0 mm. Proctor results reveal lower achievable dry density and higher sensitivity to moisture. The contractor revises the source blend to broaden the curve (increasing fines slightly while keeping No.200 < 5%) and re-tests. The updated gradation meets density targets and improves stability under construction traffic.

Specification Insight

Broaden gradation → denser packing → higher \( \gamma_d \) and lower \( k \) (use with drainage checks).

FAQs: Quick Answers on Sieve Analysis

How much sample do I need?

It depends on top sieve size. Coarse materials require larger masses (several kilograms) to capture representative fractions; ASTM tables provide minimums by nominal size.

When do I need to wet wash?

If particles have coatings or when fines adhere to coarse grains. Document the washed mass loss so the fines fraction enters the combined curve and mass balance remains tight.

What if my sieve and hydrometer overlap poorly?

Re-check washing, dispersant use, and hydrometer calibration temperature. Consider ultrasonic dispersion where allowed. The overlap near No.200 should be smooth on the merged curve.

How do I use the results right away?

Extract D-sizes, compute C_u and C_c, and classify (USCS). Then reference relevant internal guides: Proctor, Permeability, and Retaining Wall Design.

Where can I cite stable standards?

Use organization homepages that persist over time: ASTM, FHWA, and USACE. For hydrogeology field tests, see USGS.

Conclusion

Sieve Analysis turns raw soil into actionable numbers: percent passing, D-sizes, and gradation coefficients that forecast compaction, drainage, and stability. To rank #1 in reliability, start with representative sampling, apply method-compliant washing and shaking, verify mass balance, and merge with hydrometer and Atterberg Limits to classify fines correctly. Feed the curve into your compaction specs, drainage and filter designs, and foundation assessments; cross-link results within your Geotechnical Design Software to maintain a single source of truth. Anchor procedures to stable references at ASTM, FHWA, and USACE. With disciplined QA/QC and clear reporting, your gradation data will seamlessly support earthwork production, foundation design, and long-term performance.