GRANULOMETRICAL CLASSIFICATION STUDY FROM THE DENSIMETER METHOD

Reference	Presenter	Authors (Institution)	Abstract
09-115	CAMILA TAVARES BRASILEIRO	Santana, G.L.(Universidade Federal da Paraíba); FERREIRA, H.S.(UFPB); BRASILEIRO, C.T.(UFPB); DE AZEREDO, G.A.(Universidade Federal da Paraíba);	The granulometric analysis is a basic tool in the process of characterization of the particulates that quantifies the size distribution of its individual particles. It is frequently used in the study of soils for the determination of the granulometric fractions, these being described based on the size of the particles. The smaller fractions (silt and clay) are separated by sedimentation techniques, such as the densimeter, which correlates particle size with sedimentation velocity in a liquid environment. However, the standardization of particle size for each fraction may lead to errors in soil classification. The objective was to study the densitometer method for determining the particle size distribution, standardizing the preparation of samples following the Brazilian Standard (NBR 7181), comparing it with the standardization of fractions determined by the Brazilian Association of Technical Standards (ABNT). Three samples were used, consisting of: 100% Kaolin, 50% Kaolin and 100% Quartz, the material being passed through the sieve #200. The samples was characterized by X-ray diffraction, thermogravimetric analysis, differential thermal analysis and X-ray fluorescence. It was possible to obtain the grain size distribution curve of each sample studied, as well as their respective clay, silt and sand fractions. The results obtained were compared with the granulometric classification determined by the fractions standardized by ABNT. This comparison indicated that the sample of kaolin, strictly clayey, presented the sum of the percentages of the silt fraction and sand larger than the clay fraction. The quartz sample, strictly sandy, presented the sum of the percentages of the clay and silt fraction higher than the sand fraction, proving a low capacity of deagglomeration of the grains by the method, which could lead to errors in the classification of the soils.
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