Comparative Study of Cement Columns in Improving The Engineering Properties of Silty Soil

This work aims to study the improvement of silty soil properties using different cement column methods. A silty soil was selected from Nineveh Governorate, Iraq, and its engineering properties were determined. Then, the soil was treated with different cement ratios, and samples of the cemented soil were cured for different periods at 25°C. Cement columns used in this study were implemented in the soil in two ways: The first one is the dry method, and the second method involved adding cement to the soil in a solution at a water/cement ratio equal to 0.4%. These columns were implemented inside the soil in a laboratory model and left to cure for 28 days before testing. The results indicated that the dry-implemented cement columns yielded greater improvements in the bearing capacity of the silty soil than those constructed using the wet method, with the bearing capacity increasing by 3 and 2 times for the dry and wet-implemented cement columns, respectively. Also, stress-settlement behavior was improved with cement columns, and the improvement ratio was higher with the dry method than with the wet method. Cement ratios and different curing periods contributed to a significant reduction in the collapse potential and improvement in compressive strength, which is an outcome of the products of pozzolanic reactions. Finally, these methods can represent an ideal solution for treating silty soils locally compared to other techniques that may be costly and time-consuming, especially at great depths.