REDUCING CORROSIVE ANION DISSOLUTION IN SABKHA SOIL UNDER LONG-TERM LEACHING BY BITUMEN ADDITION.

Corrosive chloride (Cl^-) and sulfate (SO₄^2-) in sabkha are major environmental factors accelerating the deterioration of concrete structures with steel rebars or steel structures through long-term exposure. The dissolution of these corrosive anions from the surrounding soil must be reduced to increase the lifespan and durability and to ensure the protection of such structures. This study investigated the impact of bitumen addition on the amount of leached corrosive Cl^- and SO₄^2- in terms of quantity and rate as the percentage of total dissolved solids. Representative sabkha soil samples obtained from southern Kuwait were blended with various bitumen contents and leached with distilled water for more than 25 days, and the leached pore volumes were examined for the detected anions. Bitumen percentages of 0%, 4%, and 12% (by dry weight of sabkha) were selected as the mixing percentages based on geotechnical testing (density results obtained via modified Proctor tests) below and above the optimum bitumen contents. Results show that corrosive anion dissolution is reduced more in the bitumen-mixed sabkha than in the natural soil samples. The SO₄^2-and Cl^- concentrations almost diminish at the early leaching stages in the 12% bitumen-mixed sabkha sample, showing a strong reduction trend in the corrosive anion concentration. These findings highlight the importance of the waterproofing effect of bitumen in reducing corrosive anion dissolution from sabkha soil, which will reduce the impact of these soils on various structures, particularly buried gas, or oil steel pipes, and improve the effectiveness of other protective methods used for these structures. [ABSTRACT FROM AUTHOR]