Compaction and Strength of Slightly Organic Soils

The objectives are to examine the variation of these properties with organic content and to compare the behavior of mechanical mixtures with that of natural samples of comparable organic content. The effect of mineralogy is also studied to check its possible influence on mechanical behavior and on the organic content determination. Two methods of organic content determination, ignition and wet digestion, were used and the results compared. It was found that, for the soils studied, ignition at 400° C was appropriate as a test for organic content. While minor organic content had a strong influence on the compaction behavior, its effect on strength is much less than that of minor mineralogical or structural differences. Oven-drying was found to reduce the influence of the organic matter. Mixtures behave in compaction like natural samples of similar organic content.