Specific Surface Area by Colorimetry and Image Analysis

by Salva Ramirez, M., & Santamarina, J. C
Article Year: 2021


Salva Ramirez, M., & Santamarina, J. C. (2021). Specific Surface Area by Colorimetry and Image Analysis, Geotechnical Testing Journal, 45 (1)


Specific surface area is more informative than grain size for fine-grained sediments where S s>1m 2/g. In fact, specific surface area plays a central role in engineering properties and processes in fine-grained soils including pore size and bioactivity; fabric, plasticity and rheology; hydraulic and electrical conductivity; compressibility and residual friction angle; and all forms of coupled processes. This research advanced a dye adsorption method using digital image colorimetry implemented with smartphone technology. In particular, adopted a water-based approach to reach internal surfaces in platy phyllosilicates, selected short dye molecules to reduce the range of potential molecular contact area, and developed a physics-based adsorption model to analyze the complete dataset to minimize the uncertainty in specific surface area determinations. The study involved fine-grained soils with distinct mineralogy and specific surface area (from 1 to 600 m 2/g), and various cationic dyes and a protein to explore the effect of molecular size and shape and pH effects. Crystal violet emerged as a reliable dye for soil characterization. Time-dependent measurements confirmed second order kinetics and highlight the importance of adsorption time.


Characterization and Handling of Powders and Bulk Solids Texture, Plasticity and Density Characteristics of Soils Surface and Subsurface Characterization