The validity of laser diffraction system to reproduce hydrometer results for grain size analysis in geotechnical applications

Hamzah M. Beakawi Al-Hashemi*, Omar S. Baghabra Al-Amoudi, Zain H. Yamani, Yassir M. Mustafa, Habib ur Rehman Ahmed

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The grain size analysis plays a significant role in any geotechnical study. The grain size analysis, by means of sieving, is usually used for coarse material of particle size > 75 μm. For the fine material; the sedimentation methods are frequently adopted (e.g., hydrometers). Other methods also exist such as electron microscopy, digital image analysis and laser diffraction. The fine geomaterials commonly undergo agglomeration which makes the recognition of individual grain size using digital image analysis or electron microscopy challenging. To facilitate and enhance the grain-size analysis, this study was conducted using the Laser Diffraction System (LDS). Seven samples with different nature (composition and texture) and sources were analyzed by hydrometer and LDS. For LDS, various factors were studied such as air pressure, sonication, dilution, refractive index, and distribution method (volume or number). The results were compared qualitatively and quantitatively based on soil classification systems, fractal dimensions, and other parameters. Furthermore, this study provided a novel criterion to determine which LDS distribution method (volume or number) is to be used depending on the Liquid Limit. A combined sieve-LDS system is recommended to obtain the entire grain size distribution. It is concluded that the LDS is a viable technique that can replace the time-consuming hydrometer method to assess the grain-size distribution.

Original languageEnglish
Article numbere0245452
JournalPLoS ONE
Issue number1 January
StatePublished - Jan 2021

Bibliographical note

Publisher Copyright:
© 2021 Al-Hashemi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

ASJC Scopus subject areas

  • General


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