Tests were conducted to investigate desiccation cracking of three compacted liner soils obtained from local landfills in southeast Michigan. The soils had low plasticity with varying fines content. Large-scale samples of the soils were subjected to wetting and drying cycles. Surficial dimensions of cracks and suction in the soils were monitored. Surficial dimensions of cracks were quantified using the crack intensity factor (CIF), which is the ratio of the surface area of cracks to the total surface area of a soil. All of the soils were subjected to a compaction-dry cycle (i.e. soils were allowed to dry after compaction) and a subsequent wet-dry cycle. An additional sample of one of the soils was subjected to a compaction-dry cycle and three wet-dry cycles. The maximum CIF obtained in the tests was 7% and suctions exceeding 6000 kPa were recorded. It was observed that cracking was affected by the fines content of the soils. In general, high suctions, rapid increases in suctions, and high amount of cracking were observed in soils with high fines content, with less cracking observed in soil with low fines content. In addition, it was observed that cracking increased significantly due to addition of moisture to the soils. The CIF for wet-dry cycles were significantly greater than the CIF for compaction-dry cycles. Subsequent to moisture addition to the soils, critical suctions that caused a significant change in CIF during the drying cycles were <1000 kPa for all the soils. In the test with multiple wet-dry cycles, the amount of cracking did not change significantly after the second cycle.

Tests were conducted to determine the variation of water content and pore water suction for compacted clayey soils. The soils had varying amounts of clay fraction with plasticities ranging from low to high plasticity. The unsaturated soil behavior was investigated for six conditions, covering a range of compactive efforts and water contents. The experimental data were fit to four commonly used models for the water content-pore water suction relationship. Each model provided a satisfactory fit to the experimental data. However, the individual parameters obtained from the curve fits varied significantly between models. The soil water characteristic curves �SWCCs� were more sensitive to changes in compaction effort than changes in compaction water content. At similar water contents, the pore water suction increased with increasing compaction effort for each compaction condition and soil type. For all compaction conditions, the lowest plasticity soils retained the smallest water content and the highest plasticity soils retained the highest water content at a specified suction. In addition, SWCCs for soils compacted in the laboratory and in the field were similar.

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