Influence of Bacterial-Treated Cement Kiln Dust on Strength and Permeability of Concrete: Fid-Bau Portal

Influence of Bacterial-Treated Cement Kiln Dust on Strength and Permeability of Concrete

Singh, Malkit

AbstractCement kiln dust (CKD), a waste by-product, is a major problem at many cement manufacturing plants because of high alkalinity, metals, and sulfates. CKD possesses the same cementitious characteristics as those of cement, but the use of high-alkaline cement kiln dust reduces the quality of the cement and the strength of the concrete. In this study, the CKD used contained high alkali (1,467 mg/L) and hardness (467 mg/L) content in leachate, which on treatment with bacterium Bacillus halodurans strain KG1 showed a decrease of 67.3% alkalinity, 85.6% hardness, 46% K2O, and 27% SO3 in powdered CKD after 20 days of treatment at 35±2°C. This study investigates the effect of bacterial-treated CKD as a partial replacement (10, 20, and 30%) for portland cement on compressive and splitting tensile strength, water absorption and porosity, ultrasonic pulse velocity, and chloride permeability of concrete at the age of 28 and 91 days. Utilization of 10% bacterial-treated CKD in concrete resulted in 26.6 and 25.6% increases in compressive and splitting tensile strength at 91 days of curing compared with the control (CC) treatment. Reduction in both water absorption (64%) and porosity (53%) was observed. Similary, the reduction in chloride permeability was 22%. SEM and XRD analysis revealed increased formation of calcium silicate hydrate (CSH) gel that resulted in dense structure and low permeability.