Use of Cement Kiln Dust for Improving the Geotechnical Properties of Collapsible Soils

Abstract

The collapsible soils with severe collapsing problems cover many areas of new urbanized cities in Egypt. They are considered as one of the most challenge problems in geotechnical engineering, where they create major damages in most of engineering structures and infrastructures due to many bad human activities that cause infiltration of water through the foundation collapsible sand layers associated with abrupt decreasing of their volume. In this study the collapsible soil was stabilized using various dosages of cement kiln dust (CKD) as an economical alternative to the other expensive stabilizing agents as lime and cement, whereas it could consume considerable amounts of this harmful material with good economical feedback and positive environmental impact as well as enhance the undesirable geotechnical characteristics of collapsing soils under engineering structures and infrastructures. This study reveals that by adding CKD, the workability of the treated sand soils is increased by increasing the unconfined compressive strength (UCS) up to 4310 kPa after 56 curing days, and the shear strength parameters (up to 85.54 kPa for cohesion, C, and from 34.6 to 38.15° for internal friction angle, ф), as well as by decreasing the collapse index (Ie) from 15.35 to 0.495% and the permeability coefficient (k) from 1.38 × 10–3 to 3.02 × 10–6 cm/sec. The CKD dosages between 25 and 45% mixed to total soil dry weight may be suitable for the most engineering purposes and sufficient to upgrade the collapsible sand soils and may raise the CKD content to about 50%.