Question

What is the importance of particle size analysis for soil sample?

Answer 1

Importance of Particle Size Distribution Emphasized in Proposed ASTM Soil and Rock Standards

Particle size distribution, also known as gradation, refers to the proportions by dry mass of a soil distributed over specified particle-size ranges. Gradation is used to classify soils for engineering and agricultural purposes, since particle size influences how fast or slow water or other fluid moves through a soil. Two proposed new ASTM standards provide test methods for determining particle size.

ASTM WK11776, Test Methods for Particle-Size Distribution (Gradation) of Fine-Grained Soils Using the Sedimentation (Hydrometer) Analysis, and ASTM WK38106, Test Method for Particle-Size Analysis of Soils Combining the Sieve and Sedimentation Techniques, are being developed by Subcommittee D18.03 on Texture, Plasticity and Density Characteristics of Soils, part of ASTM Committee D18 on Soil and Rock.

“Knowing the grain size distribution of a soil is important for a variety of reasons and for a range of uses,” says Kendra Adams, senior quality assurance engineer, Fugro Consultants Inc., and a D18 member. “Gradation results influence the design of earthen dams, levees and landfills.”

Once approved, the proposed standards will be useful to professionals in several fields:

• Civil and geotechnical engineers to assist in designing or making recommendations regarding a project site, particularly regarding water drainage;
• Geologists in determining depositional environments and provenance;
• Agronomists to assist with drainage or nutrient delivery to crops;
• Regulatory and accreditation bodies for a consistent and accepted method by which to assess laboratories; and
• Laboratories for a defined method by which to perform the test.