Effect of Emulsified Asphalt on Expansive Soil Strength and Swelling

Abstract

Some clay soils classified as extended soils threaten the structures resting on them. Many additives are available to improve the properties of expanded soils. This study tries to investigate the consequences of wetting-drying cycles on the swelling behavior of modified expansive clayey soils under laboratory conditions by modifying expansive clayey soil samples using emulsified asphalt. Five different percentages of emulsified asphalt were used: (2, 4, 6, 8, and 10) %. The natural and treatment soils were tested for classification, specific gravity, compaction characteristics, free swell and swell pressure, consolidation, and compressive strength. The liquid limit and plasticity index have been lowered by adding Emulsified Asphalt. After that, the effects of Emulsified Asphalt on undrained shear strength characteristics (cohesion and friction angle) have been studied. The results revealed that when the emulsified asphalt content was increased to 10%, the swelling pressure and swelling potential decreased by 58 and 78 %, respectively. The swell and shrink improvement factor for the 10% emulsified asphalt addition is always larger than 75%. As the duration of wetting-drying cycles increased, the swelling pressure and swelling potential values were also reduced. The plastic limit, on the other hand, increased as the Emulsified Asphalt content increased. Increasing the amount of Emulsified Asphalt increased the maximum dry unit weight values, whereas the optimum water contents increased. It was concluded that emulsified asphalt stabilization may be useful for expansive clay as it improves compressive shear strength.

Keywords

• expansive soil
• swelling
• emulsified asphalt
• soil stabilization
• clay soil
• shear strength