Swell‐Shrink Behavior of Compacted Clay

The results of this study show that the initial amount of swell and shrinkage for a clay compacted at a moisture content that was 6% wet of modified Proctor optimum was small. By allowing the compacted silty clay to cure, bonds were developed that further reduced the amount of initial swell and shrinkage. But after repeated wetting and drying cycles, the amount of expansion and shrinkage dramatically increased. Whatever effect compaction at a high moisture had was destroyed by wetting and drying cycles. In terms of practical applications, for a clay compacted over optimum and protected from wetting and drying cycles, aging may result in the development of bonds that substantially reduce long‐term swell. But if the compacted clay should dry out prior to placing the foundation, or if the clay is subjected to wetting and drying cycles, the beneficial effect of compacting the clay at a high moisture content will be destroyed, causing the soil to become significantly more expansive.