Study of the Effectiveness of Cement Kiln Dusts in Stabilizing Na-Montmorillonite Clay

Abstract

The feasibility of using cement kiln dusts (CKDs) as potential stabilizing agents for Na-montmorillonite clay was investigated using a suite of four CKDs with different chemical and physical characteristics. The Atterberg limits, pH values, unconfined compressive strengths (UCSs), stiffnesses (stress-strain behavior), and stability of the CKDs-modified Na-montmorillonite clay were measured as functions of CKDs content and curing periods. These properties were compared with those of the untreated clay to determine the extent of enhancement, which was used as a measure of effectiveness of CKDs as stabilizers. All CKDs considerably decreased the plasticity index, thereby improving the workability of the clay, while they also considerably increased the initial pH value of clay, providing a favorable environment for further chemical (pozzolanic) reaction. The addition of CKDs and subsequent compaction substantially increased the UCS and the stiffness of the clay, thus improving its structural properties. The extent of improvement of the clay characteristics was found to be a function of the chemical composition of the particular CKD, specifically its free lime content. It was also found that the length of curing period after compaction had a major role in the stabilization process.