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New Mexico State University (2008)

Experiments with methods for particle size analysis of gypsic soils

Riggs, Justin

Titre : Experiments with methods for particle size analysis of gypsic soils

Auteur : Riggs, Justin

Université de soutenance : New Mexico State University

Grade : Master of Science (MS) 2008

Résumé
Gypsum is a common mineral in many dryland soils throughout the world. Gypsic soils have unique properties that impact roads, foundations, metal and concrete. One challenging aspect of gypsic soils is determining the particle size distribution. Because of gypsum’s softness (1.5-2.0 on the Mohs scale) gypsum particles can be broken by rolling pins and shakers. Because of its solubility (2.41 g/L), gypsum particles can be dissolved during sedimentation. This research effort explores ways to prevent gypsum dissolution, while conducting textural analysis by using low viscosity oil, NaCl solution, saturated gypsum solution, a combination of a saturated Na2SO4 and gypsum solution, a method with no clay sized gypsum, and finally, a filtration method where the sand and the silt is sieved in saturated gypsum solution. Although low viscosity oil prevented gypsum dissolution, it was unsuitable because of problems with the drying of the oil-saturated sample and cost. NaCl solution was unsuitable because it did not prevent gypsum dissolution as a result of ion pairing. Saturated gypsum solution prevented gypsum from dissolving because of the common ion effect ; however, clay particles flocculated in the solution. The use of Na2SO4 and saturated gypsum solution was used to disperse these particles. However, with high concentrations of Na+ the clay particles still flocculated. The method based on the assumption that no gypsum exists in the clay fraction was proven inaccurate with scanning electron microscope (SEM). Finally, the filtration method, in which silt is collected on high flow glass fiber filter paper under vacuum, shows good results when compared to the standard pipette method.

Mots Clés : gypsic soils, technique, particle size analysis, technique, soil methods, thesis

Présentation (Jornada NMSU)

Présentation

Page publiée le 3 novembre 2017, mise à jour le 24 décembre 2019