Utilization of Cement Kiln Dust and Fly Ash in Cement Blends in Saudi Arabia

Cement kiln dust produced in a local cement production plant in Saudi Arabia, along with fly ash resulting from combustion of heavy fuel oil in a local power generation plant were utilized as waste materials blended with ordinary Portland cement at various ratios. These blends were tested for their water requirements for normal consistency, initial setting times, and compression and tensile strengths, and were compared to those of Portland cement. Test results show that satisfactory mechanical strength (a minimum of 94% of compression strength of ordinary Portland cement) can still be achieved in blends utilizing 90% cement and not more than 4% fly ash. Adequate mechanical strengths (a minimum of 80% of compression strength of Portland cement) were achieved in blends utilizing as little as 70% cement when only kiln dust was blended. Hundred thousands of tons of cement-kiln dust (CKD) are generated annually from cement plants in the Kingdom of Saudi Arabia. The bulk of this dust, mostly with high alkali contents, is land filled with a significant financial loss to the local cement industry in terms of the value of raw materials, processing, and energy consumption during pyroprocessing, dust collection, and disposal. This fine dust is emitted from cement kilns to prevent the build up of excessive salts in the cement product. The alkali salts in the dust are derived from the clay raw