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AASHTO T88 – Standard Method of Test for Particle Size Analysis of Soils


AASHTO T88 is a standard test method used to determine the particle size distribution (gradation) of soils. This analysis is crucial in geotechnical engineering as it provides valuable information about the soil’s composition, behavior, and suitability for various applications, such as earthworks, embankments, foundations, and pavements.

Key aspects of AASHTO T88:

  • Purpose: the primary objective of this test is to quantify the percentage of different particle sizes present in a soil sample. Particle size distribution is a fundamental soil property that influences its permeability, shear strength, compressibility, and other engineering properties.
  • Test procedure: the test involves separating the soil sample into different size fractions using a series of sieves with progressively smaller openings. The sieves are arranged in a stack, with the largest opening size at the top and the smallest at the bottom. The soil sample is then placed on the top sieve and shaken or vibrated, allowing the particles to pass through the sieves based on their size. The mass of material retained on each sieve is measured, and the percentage passing each sieve is calculated.
  • Fine-grained soils: for fine-grained soils (particles smaller than 0.075 mm), a hydrometer analysis is typically conducted in addition to the sieve analysis. This involves measuring the density of a soil-water suspension at different time intervals to estimate the percentage of particles finer than specific sizes.
  • Significance: the particle size distribution of soil is a critical parameter for geotechnical engineers. It helps them understand the soil’s behavior under different loading and environmental conditions, allowing for the appropriate selection of soil types for specific applications and the optimization of earthwork and foundation designs.

Applications of AASHTO T88:

  • Soil classification: particle size analysis is a key component of various soil classification systems, such as the Unified Soil Classification System (USCS) and the AASHTO Soil Classification System.
  • Geotechnical design: the results of the sieve analysis are used in geotechnical design calculations to assess the soil’s permeability, shear strength, and compressibility. This information is crucial for the design of earthworks, foundations, and other geotechnical structures.
  • Quality control: the test is used to ensure that the soil materials used in construction projects meet the specified gradation requirements and conform to industry standards.

AASHTO T88 Accredited Laboratory

Applied Testing & Geosciences, LLC is accredited for performing tests using the AASHTO T88 standard.

Our laboratory offers comprehensive soil testing services, including particle size analysis according to AASHTO T88. Our experienced technicians utilize calibrated sieves and hydrometers and adhere to standardized procedures to ensure accurate and reliable results for your geotechnical projects.

Contact us for more information.



particle size distribution; sieve analysis; hydrometer analysis; soil; fine-grained soil; coarse-grained soil; gradation; sieve; hydrometer; meniscus; dispersion agent; sedimentation