Strength analysis of fragipans in some loess-derived soils in Louisiana

The objective was to quantify the strength characteristics of fragipans found in selected loess-derived soils in northeastern Louisiana. Three study sites were selected on the Macon Ridge, which is blanketed by a Peoria loess. Two sites were selected on the Bastrop Ridge, which is covered by a pre-Peoria loess. In general, higher sensitivity values for fragipan horizons from the Macon Ridge sites indicated that rigidity in these fragipan horizons is derived in part from binding agents. Low sensitivity values measured on fragipans from the Bastrop Ridge sites indicated that cohesive binding agents have little effect in providing rigidity for these fragipan horizons. Dried undistrubed fragipan material exhibited strength values a full order of magnitude greater than those measured on samples tested at field moisture contents. Results indicate that the fragipans in soils developed in older loess deposits on the Bastrop Ridge have a lower component of strength derived from interparticulate binding agents than those fragipans in soils developed in the younger loess deposits on the Macon Ridge. -from Authors