The Influence of Laboratory Compaction Methods on Soil Structure: Mechanical and Micromorphological Analyses

Abstract

This paper addresses the influence of the static and dynamic laboratory compaction procedures in the compaction curves and mechanical strength of two residual soils from the Zona da Mata Norte, in the state of Minas Gerais, Brazil. The laboratory testing program was directed to: (i) two gneissic residual soils, respectively, with silty-sandy clay and clayey-silty sand textures; (ii) compaction of specimens at the standard Proctor compaction effort and at the optimum water content (wot), as well as at wot - 3% and wot + 2%; (iii) determination of the unconfined compressive strength of the compacted specimens; (iv) micromorphological analysis of thin sections of the compacted specimens using optical microscopy; (v) statistical analysis of the laboratory testing program data. Conclusions are, as follows: (i) there was statistically significant influence of the compaction procedures on the optimum compaction parameters; (ii) for both soils, significant structural changes represented by variations in the unconfined compression strength were observed evidencing the importance of the soils formation processes in their mechanical responses when compacted; and (iii) differences in the soils structures produced by the static and dynamic compaction procedures were identified through incorporation of the micromorphological analysis.