Grain Size Analysis of Soil – Sieve Analysis Procedure, Calculation & Interpretation Author: Kishor Kumar · Updated: February 2026 · Read time: ~15 minutes 1. Introduction The Grain Size Analysis of Soil, commonly known as the Sieve Analysis, is a fundamental laboratory test used to determine the particle size distribution of soil. It plays a crucial role in highway and civil engineering projects. Soil Identification and Classification Most of the methods for soil identification and classification are based on certain physical properties of the soils. The commonly used properties for the classification are the grain size distribution, liquid limit and plasticity index. These properties have also been used in empirical design methods for flexible pavements, and in deciding the suitability of sub grade soils. Grain size analysis also known as mechanical analysis of soils is the determination of the percent of individual grain sizes present in the sample. The mechanical Analysis consists of two parts: Determination of coarse material using sieves. Analysis of fine grained fraction by sedimentation method. The sieve analysis is a simple test consisting of sieving a measured quantity of material through successively smaller sieves. The weight retained on each sieve is expressed as a percentage of the total sample. The sedimentation principle has been used for finding the grain size distribution of fine soil fraction; two methods are commonly used: Pipette method Hydrometer method The grain size distribution of soil particles of size greater than 75 micron is determined by sieving the soil on a set of sieves of decreasing sieve opening placed one below the other and separating out the different size ranges. Two methods of sieve analysis are as follows: Wet sieving applicable to all soils Dry sieving applicable only to soils, which have negligible proportion of clay and silt The soil received from the field is divided into two parts: one, the fraction retained on 2mm sieve and the other passing 2mm sieve. The sieve analysis also may be carried out separately for these two fractions. The fraction retained on 2mm sieve may be subjected to dry sieving using bigger sieves and that passing 2mm sieve may be subjected to wet sieving; however if this fraction consists of single grained soil with negligible fines passing 0.075mm size, dry sieving may be carried out. Proper soil gradation ensures good drainage, uniform compaction, and strong load-bearing capacity. Coarse-grained soils are generally suitable for sub-base layers, while fine-grained soils may require stabilization. 2. Purpose of Grain Size Analysis Determine particle size distribution and gradation Assist in soil classification (Gravel, Sand, Silt, Clay) Design subgrade, embankment, and pavement layers Assess permeability and drainage characteristics Guide soil stabilization decisions 3. Applicable Standards IS 2720 (Part 4) – Grain Size Analysis IS 2720 (Part 1) – Sample Preparation MoRTH Specifications – Subgrade, GSB & WMM ASTM D6913 / D422 – International standards 4. Apparatus Required Standard sieve set (4.75 mm to 75 μm) Mechanical sieve shaker Weighing balance (0.1 g accuracy) Oven (105°C to 110°C) Hydrometer (for fine soils) Brush, spatula, containers 5. Sample Preparation The soil sample should be oven-dried at 105°C–110°C and cleaned of organic matter. Lumps should be broken gently without crushing particles. Take ~500 g dry soil sample Ensure moisture content is minimal Remove oversized particles and debris Mix thoroughly for uniformity 6. Test Procedure – Sieve Analysis Sieve Analysis – Coarse Fraction (a) Fraction retained on 2.0mm sieve: Sufficient quantity of the dry soil retained on 2.0mm sieve is weighed out. The quantity of sample taken may be increased when the maximum size of particles is higher. The sample is separated into various fractions by sieving through the set of sieves of sizes 100 mm, 63 mm, 20 mm, 6 mm, 4.75 mm and 2 mm IS sieves. Additional sieve sizes may also be introduced if necessary. After initial sieving, the material retained on each sieve is collected, the lumps are broken down using mortar and rubber covered pestle and is re-sieved. Thus, the soil fraction retained on each sieve is carefully collected and weighed. Sieve Analysis – Fine Fraction (b) For the fraction passing 2.0mm sieve and retained on 0.075mm sieve: Dry sieving may be done in the case of soils which are cohesion less, single grained and without lumps. Rifling or quartering method takes the required quantity of soil sample, dried in oven at 1050 to 1100°C and is subjected to dry sieve analysis using a set of sieves with sieve openings 2.0 mm, 0.6 mm, 0.425 mm, 0.15 mm and 0.075 mm, pan and lid. Additional sieves may be used or any of the sieves removed, depending upon the requirement of the test. The material retained on each sieve and on the pan are separately collected and weighed. Wet sieving may be adopted in the case of clayey or cohesive soils. Required quantity of sample taken by riffling is weighed. The sample is spread in a tray or bucket and covered with water. In case of soils having fractions that are likely to flocculate, a dispersing agent like sodium hexametaphosphate (2.0g) or sodium hydroxide (1.0g) and sodium carbonate (1.0g) per liter of water may be added to the water. The mix is stirred and left for soaking. The soaked soil specimen is placed over the set of sieves with the finest sieve and pan at the bottom and washed thoroughly. Washing is continued till the water passing each sieve is substantially clean. The fraction of each sieve is emptied carefully without loss of material in separate trays, oven dried at 1050 to 1100°C and each fraction weighed separately. Calculations – Sieve Analysis CALCULATIONS: The weight of dry soil fractions retained on each sieve is calculated as a percentage of the total dry weight of the sample taken. Results – Grain Size Analysis RESULTS: The results are plotted on a semi-logarithmic graph with the grain size or sieve size on the X-axis (log scale) and the percentage finer of each sieve on the Y-axis (ordinary scale). The smooth curve joining the
