EFFECT OF FINE MATERIAL ON COMPACTION CHARACTERISTICS OF SUBBASE MATERIAL USING THE SUPERPAVE GYRATORY COMPACTOR

Soil compaction is defined as a method for mechanically increasing the density of soil by reducing the air volume from between particles. The main objectives of compaction are increasing strength, stiffness and stability of soil by reducing its compressibility and decreasing permeability of the soil mass by reducing its porosity. The Superpave Gyratory Compactor (SGC) was developed to compact pavement layer samples to densities similar to that obtained in the field after construction and traffic compaction. This research targeted two primary purposes: First evaluating the effect of water content on compaction charactereristics, second investigating the effect of fine material on dry density and CBR value of subbase material. To meet these research objectives, various water contents and percents of fine materials were used to compact the specimens. The results showed that the subbase material becomes stiffer when the fine materials increases from 5 % to 10 % and 13 % and the dry density increases which leads to increase in CBR value. Boch dry density and CBR decrease with the increase of water content bove the optimum water content.