Review of Previous Studies on Gypsiferous Soil Behavior and Stabilization

Abstract

The Gypsous soil especially in Iraq have very high gypsum (calcium sulfate) contents and are highly affected by water. At dry state, a gypsum gives an illusory binder unlike on wetting when they dissolved and the shear strength decrease significantly with compressibility extensively increased and fall of structure. The present paper provides an overview of the geotechnical behaviour of gypsiferous soils, focussing on the mechanisms leading to collapses, environmental impacts and laboratory and field testing techniques commonly used in practice. Several soil stabilization methods are critically analysed including classical chemical methods (lime, cement, cement kiln dust), physical and mechanical tech- niques ( compaction, geogrids) but also sustainable alternatives such as biopolymers, nanomaterials or industrial by-products and recycled waste materials. The review shows that while there are some stabilization methods which show clear short-term benefits, little is known about long-term performance under cyclic wetting–drying and saline conditions.  In this regard, special consideration should be provided to the gypsiferous soils in ecologically sensitive regions, such as the Najaf Sea. The paper highlights the required research and demonstrates the necessity for low-environmental-impact, sustainable and locally available stabilization materials to delay loss of bearing capacity and stabilize long term the performance of substrate geotechnical works placed on gypsiferous soil.