Controlled low strength materials incorporating cement kiln dust from various sources

This paper presents the development of controlled low strength materials (CLSM) incorporating cement kiln dust (CKD) from four different sources or manufacturers. A preliminary study (Phase I) was conducted to understand the influence of CKD on fresh and strength properties of 12 selected CLSM mixtures where CKD and cement contents varied from 4% to 45% and 2% to 4% of total mass, respectively. Subsequently, four best CLSM mixtures were selected from Phase I and used in combination with the four types of CKD (from four sources) to provide 16 CLSM mixtures for a detailed study (Phase II). The detailed study investigated fresh and hardened properties, addressed durability issues, compared the performance of different types of CKD, and made recommendations for suitable mix designs for field applications. CLSMs with larger quantities of CKD showed higher drying shrinkage and seemed to have lower freeze–thaw and wetting–drying resistances. CLSM appeared to be less permeable than the well-drained soil. Correlations between properties such as California bearing ratio (CBR), compressive strength, and setting time are also established. The source/type of CKD influenced fresh, mechanical and durability characteristics of CLSM mixes due to variations in chemical compositions. The research suggests suitable CLSM mixes either derived from the combination of CKD (10% maximum) and cement (4% maximum) or CKD (30% maximum) alone. The developed 16 CLSM mixtures from four different types of CKD should provide the user a range of alternatives for the selection of suitable mix for a specific project. Sustainable development in the cement industry can be achieved by producing CKD based CLSM as it reduces the use of cement and consumes a co-generated product.