Potential of limestone powder to improve the stabilization of sulfate-contained saline soil

The geotechnical properties of soils differ from area to area, depending on the origin of soil, environmental conditions of a region, and soil treatment processes. As a subgrade material in pavement construction, however, the soil is required to meet specific standards for its engineering properties, such as plasticity, deformability, strength, and durability parameters. For this purpose, soil undergoes a stabilization process, in which it is treated with chemical additives. This paper studies the potential of limestone powder as a stabilizer in combination with cement in the stabilization of sulfate-contained saline soil. For this purpose, silty sand (A-2-4(0) according to AASHTO soil classification system) containing high sulfate and sodium contents was stabilized with 6% and 8% cement by dry weight, 2% and 4% limestone powder at fixed 4% cement content, and 2% limestone powder by dry weight at 6% cement content. Series of tests were performed to determine the improvement of geotechnical properties of these mixtures, such as unconfined compressive strength, Atterberg limits, three-dimensional (3-D) swelling, and dielectric constant. Experimental results show that the addition of limestone powder to the cement-treated saline soil decreases soil plasticity, increases maximum dry density, improves strength parameter, reduces volumetric swelling and moisture susceptibily of soil.