اصلاح آهكي خاك گچدار با استفاده از روش دومرحله اي

Sulfate-bearing soils may undergo large volume expansion and strength decrease by time when used for construction purposes. The main cause appears to be the formation of ettringite and thaumasite, highly water expansive minerals. Previous studies have shown that the lime or Portland cement treatment of these soils may develop even adverse results particularly in soils containing soluble sulfates such as sodium sulfates. A method involving the double application of lime appears to be one of the practical solutions for improving the strength and volume characteristics of sulfate soils. A laboratory study was conducted on a clay soil that was mixed with different amounts of lime and gypsum, employing regular as well as double application approaches. The specimens were soaked in water for r21 days and the amounts of swell and CBR values were measured at the end of this period. The results show a strong influence of the double application method in increasing the strength and decreasing the volume expansion of the lime treated specimens whereas the specimens prepared with the regular application exhibited large swelling and small strength characteristics upon the saturation.