The connection between soil shrinkage and pore water distribution of compacted clays using the nuclear magnetic resonance technique

The shrinkage behavior of compacted clays is crucial for evaluating deformation and failure potentials in subgrade and earth dam engineering. A series of soil shrinkage and nuclear magnetic resonance tests were performed on the same specimen for a wide range of compacted clays under drying condition. The correlation between soil shrinkage on the macroscale and pore water evolution on the microscale was thoroughly investigated. The experimental results show that structural shrinkage depends on the initial structure of compacted clay, while the impact of compaction density on basic and residual shrinkages is relatively minimal. The distribution of the transverse relaxation time T2 in a saturated specimen effectively indicates the transitional water content from the structural to basic shrinkage using the NMR technique. Furthermore, a nearly identical maximum T2 could serve as the characteristic time for identifying the other transitional water content between basic and residual shrinkage stages in compacted clays. Two transitional water contents in the shrinkage curve and Atterberg limits are highly correlated, indicating a potential method for estimating the soil shrinkage curve of compacted clays using fundamental soil properties.