Volume 6, Issue 8 (September 2009)
A Comparative Evaluation of Various Additives Used in the Stabilization of Sulfate Bearing Lean Clay
A laboratory study was conducted on both raw and stabilized clay specimens to evaluate short- and long-term performance of three different additives, namely, hydrated lime, class C fly ash (CFA), and cement kiln dust (CKD), for providing better treatment of sulfate rich lean clay. Short-term performance evaluation experiments included Atterberg limits, resilient modulus (Mr), modulus of elasticity (ME), and unconfined compressive strength (UCS), after 28 days of curing. Long-term performance was evaluated in terms of moisture susceptibility (tube suction test) and three-dimensional swell during 120 days of capillary soaking. At the end of 120 days, specimens were also tested for Mr, ME, and UCS, as additional indicators to long-term pavement performance. Short-term performance evaluation projected 15 % CKD with highest improvement, while long-term performance evaluation showed 15 % CFA providing maximum enhancements after 120 days of capillary soaking. The study further indicated swelling of specimens stabilized with lime and CKD; however, CFA helped in reducing the swelling. All the percentages of additives used in the study helped in reducing the moisture susceptibility of clay. Mineralogical studies such as scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction were also used to verify research findings observed from the macro test results.