Comparison between hydrometer and laser diffraction methods in the determination of clay content in fine-grained soils

Clay content is the main characterizing parameter when classifying fine-grained soils. Hydrometer method (HD) commonly used in geotechnics to obtain grain size distribution properties of However, this test laborious and time consuming as compared alternative methods such laser diffraction (LD). In study, a comparison between results for clay 19 samples from different locations Finland using HD LD was carried out aiming at obtaining mathematical expression that allows transform measurements into results. The were statistically showing significant differences these two techniques underestimation by observed. Based on results, reliability determination discussed.