Comparison of the effect of using class C and F fly ash on the stabilization of dispersive soils

Abstract

Dispersive soils were not always recognized as erosive or problem soils until recent years although quite common in nature. Many problems have been experienced with dispersive soils in different projects such as dam embankments and roadway embanlcments. This problem is worldwide, and structural failures referred to dispersive soils have arisen in many countries. Stabilization of dispersive features of problematic soil is an important research topic in engineering applications. Recently, industrial by-products are frequently used to improve the problematic soil properties so that both environmentalist and economic benefits are achieved. In this study, the effects of the fly ashes as waste materials in different classes on the improvement of the dispersive soils have been examined. Within this scope, two different clay soil samples and fly ashes in two different classes, F and C, have been used. First, geotechnical properties of the soil samples were determined. Next, pinhole, crumb, and unconfined compression strength tests were performed on the specimens prepared by standard Proctor energy level at the different percent fly ashes (0, 5, 10, 15, 20, 25, and 30%). From the test results, it is observed that the fly ash class has a significant effect on the stabilization of dispersive soils and also strength properties. It is shown that the dispersive soils can be stabilized sufficiently using class C fly ash alone. As a result ofthis study, it has been determined that class C fly ash is much more efficient than class F fly ash in the stabilization of the dispersive soils.