LABORATORY SOILS COMPACTION: EFFECT OF SPECIMEN DIAMETER AND NUMBER OF LAYERS

ABSTRACT

This paper addresses the study of the influence of specimen diameter and number of layers on the laboratory compaction curves and mechanical strength of two gneiss residual soils from Zona da Mata Norte of Minas Gerais state, Brazil, respectively with grain size distributions classified as silty-sandy clay (Soil 1) and clayey-silty sand (Soil 2) for forest road applications. Besides compaction testing data, it was determined the unconfined compression strength of soils using specimens compacted at the optimum water content (w_ot), w_ot -3% and w_ot +2% referred to the standard Proctor compaction effort and using specimens compacted with one, two and three layers as well as diameters of 35 mm, 73 mm and 100 mm, with nine replicates. For practical engineering purpose and based on statistical analysis applied to the parameters dry specific weight and unconfined compression strength it can be concluded that: (i) for both soils, there are significant differences between the compactions carried out in one and three layers, and not the same for two and three layers; and (ii) for Soil 1 (clayey soil), there are significant differences between compaction using 100 mm and the 73 mm and 35 mm diameter specimens, as well as for Soil 2 (sandy soil) these differences occurs only in the dry branch of the compaction curve.

Keywords:
Soil compaction; Unconfined compression strength; Compaction parameters